Is light slow? Or is the human perception of time just scaled down as a result of our rapid metabolism and infinitesimality? People historically mistake plants for being inanimate things with no reactivity, that they are far more simple and stupid than they truly are. Outside of a few exotic examples, plants simply operate on a wider timescale that's basically imperceptible without careful and particular observation. It becomes much more apparent how alive plants are when we observe them in a time-lapse. Now realize that plants are still relatively short-lived. The absolute oldest ones only go back to the early neolithic, that's only 14000 years or so. 1000 years is a long time for humans, but probably not for the trees where a single one can live 10x that.
From the hypothetical perspective of a star, with a lifespan measured in billions upon billions of years, the entire ecoscape of the world changes in a blink. From the sun's perspective, MENA was green just a very short while ago. Hell, Pangea wasn't that long ago. At this timescale, continental drift would be as apparent as the movement of boats are to humans. Anything that's working at the cosmic scale where the seemingly low speed of light sounds exhausting is most definitely working at this stellar perspective at the minimum. 14000 years of travel might as well be the equivalent of a 10 minute commute to the store.
Light is comparatively and objectively slow in comparison to the distances that exist. Andromeda is 1M light years from us. From that perspective, 300k kph is oddly slow actually. I love the passion that you're brining to the table though. It reminded me of the blue giant stars whose lifespans can be as short as tens of millions of years, more often hundreds though. For billions upon billions, I suppose that would be white and brown dwarfs. Although, if we could orbit black holes and harness the energy of gravity, then we're really talking long time scales. Cracking the aging problem would allow us to think in very long timescales. But I do wonder whether the human psyche could handle such long lifespans.
This leaves out the time component. Who's to say that a year is long? A galaxy a million light years away takes a million years to reach... and maybe that's a short amount of time, to the right observer.
Light could only go to Andromeda and back 1000 times before the sun burns out. That's not very many times IMO. On the scale of galaxies, light is slow relative to any timescale relevant to large objects.
There's a great video is saw. In 30 minutes it goes through the entire lifespan of the universe.
Even after all the stars die, the white dwarfs will continue to glow. And after eons, the last black holes will evaporate. The point is that the age of stars is only a tiny fraction of the lifetime of the universe. Maybe the speed of light makes sense at that scale.
But... I'm not happy with that theory. In a relatively short amount of time the expansion of the universe will increase faster then the speed of light. Which means it will be impossible to ever get information from the other side of the universe.
I find it very unreasonable that the universe imposes a speed limit on everything and then completely ignores it.
In addition to the insight, it reminded me to water a plant at a desk I no longer use. The plant's been with me through quite a bit and I have been neglecting it recently as I no longer see it regularly.
For very philosophical writings about this, read "Last and First Men" and "Star Maker" by Olaf Stapledon. Written in the 1930's, these describe on a very expansive scale the history of, respectively, humanity and the universe. Very mind bending.
yeah light _is_ actually pretty slow and we hit that in networking and optics pretty often if iirc.
like not even on a human level, universally even on a grand scale the speed of light is almost torturously slow, there’s nothing philosophical about it
Chances are that only a species who, through one way or another, has become very uninterested in warfare could have advanced to the point where they would be able to run such a simulation, otherwise they'd have ended their own existence with their shiny toys before long.
War only occurs if you have in the literal sense retarded elements in your advanced species and is nonsensical from an outside POV. A species this advanced would have fixed such shortcomings in itself long ago.
So no, I don't think they'd necessarily be very interested in watching primitive species go to war with primitive weapons.
For all we know the simulation of this universe is happening in their equivalent of an overengineered snow globe, us being an artifact nobody has noticed and that nobody would find particularly interesting if they did notice.
At the moment humans only live ~90 years which is a blip in cosmic terms, but shortly we should be able to merge with AI and live for billions of years and visit stars.
That’s one of the answers to how you could go to the stars: go sloooooow as in slow down your cognition and metabolism so the trip doesn’t take long.
Ents could fly to the stars no problem.
Makes me wonder if there might not be a bunch of star faring “slow life” out there that we don’t notice for the same reason a hummingbird doesn’t notice trees growing.
> Is light slow? Or is the human perception of time just scaled down as a result of our rapid metabolism and infinitesimality?
It's slow for humans to explore the cosmos.
"Slow" is meaningless without a frame of reference, and "humans" seems like a good frame of reference, since it's us -- and not plants or stars -- who are writing on HN to discuss this.
Because it's us, humans discussing this in HN, the frame of reference is implied and it's not necessary to spell it out.
It only seems incredibly slow in this model because it doesn't take special relativity into account. If it did, then as you approached the speed of light the Lorentz contraction would make wherever you are heading appear less far away. You can in theory get anywhere in the universe in an arbitrarily short amount of proper time your own reference frame. Of course, you might not survive the G-forces, but that's another matter.
The Lorentz factor at 0.5 c is 0.86 so this only reduces your proper travel time by about 15%. Even at 0.9c the LF is only 0.43, so it would still take you 2 years just to get to Proxima Centauri. And as you approach c, 1G acceleration speeds you less and less. And you also have to slow down at your destination.
Not out of reach if you get very close to light speed. Time would advance very slowly for you, so counterintuitively it is possible to travel 5000ly in your life time.
Although for everyone else at least 5000 years will pass, so better say goodbye to family and friend.
Hm, not sure if that is really less depressing...
Also light isn't slow. A photon instantly travels to the end of time and yet it still takes a few minutes from the surface of the sun to us. Or about 100000 years from the center of the sun to its surface.
Yeah if you have a body that can tolerate sudden jumps between reference frames you could pretty much explore the entire galaxy trivially, so long as you don't mind that few places will stay the same long enough to visit twice.
You wouldn't need a sudden jump. If you had a rocket that accelerated at a pleasant 1G forever, you could reach and stop at the center of the milky way in about 20 (your time) years, and you could reach and stop at the Andromeda galaxy in about 28 years. Play around with some of the online space travel relativity calculators--it's wild!
Of course building and fueling such a rocket is what's totally out of reach.
With a traditional rocket, I believe you'd need decreasing energy to maintain the same acceleration as the flight progressed, since you are carrying along with you and burning the fuel, and so the total mass (payload + fuel) that needs to be accelerated is constantly decreasing.
Of course there's the pesky problem that for every N kg of mass you want to accelerate at 1G for that kind of a trip, you're probably going to need somewhere on the order of N billion kg of fuel to burn.
We're already on that starship. Our engine is about 8 lightminutes away. All we need is to figure out how to steer this thing - and how to not wreck it while en route.
I would prefer the concept of people building an artificial planet/asteroid/spaceship for a starship, instead of messing with our star system. But luckily that debate is some years away and currently we cannot even figure out, how to deal with some increased CO2 levels.
How would that feel as a traveler? Does all motion slow down to a crawl, all sub-atomic particles just "freeze" and essentially your thoughts and body aging too? So it would seem like you got there in an instant?
For sure you're not just sitting there watching people get born, live and die in second and shrugging your shoulders.
You’d feel nothing out of the ordinary whatsoever. The starscape outside the ship would look strange though, shrinking into a small, blueshifted patch of sky straight ahead, while stars behind you would redshift out of the visible range. Everything moving at very low speeds relative to you would indeed appear to happen really fast.
There's about one particle of dust per million cubic metres. c is about 300 million metres/second. So even at 0.5c that's still a lot of particle collisions per second, each having significant kinetic energy.
Basically it would be like flying through explosive sandpaper. Each dust particle would be reduced to plasma, which creates problems of its own.
If you're accelerating there's also the Unruh Effect, which will raise the perceived temperature. By a lot.
There's no way to make this work with any kind of engineering we know about today.
The Unruh effect is theoretical, and no evidence at all has ever been found that it's real. It literally exists as nothing more than a hypothetical mathematical model, that also happens to be debated by others who know enough to effectively debate it, and disagree.
Mostly that it's plentiful, ablative, expendable, plus good radiation shielding (yeah, cosmic ray protons are really going to mess things up at relativistic speeds too unless there's enough mass to stop them).
It's one of those cases where you have very small numbers multiplied by very large ones. The actual risk is hard to intuit because there are so many orders of magnitude involved in both directions.
In any case it's probably a moot concern as long as we are living under the twin tyrannies of Newtons Third Law and the Rocket Equation. Building a rocket that can accelerate constantly and noticeably for weeks, months, or even years on end in order to accelerate up to a velocity where Relativity starts to matter requires an absurdly large rocket. Like converting the mass of Jupiter into rocket fuel to make it to the next habitable solar system in a couple of centuries level of craziness.
But it's also very big, and GP doesn't even specify how far of a trip they're asking about nor how small a meteorite.
"Extremely" and "very" don't cut it here. This is beyond the human ability to guess. You'd actually do at least some back-of-the-napkin math to give a real answer, and with a far enough trip, the answer may well become "Almost 100%".
If the light behind you redshifts out of the visible spectrum, would the light in front of you blueshift into dangerous territory? X-rays, gamma rays, etc?
Yes, and this provides a nice intuition about the relation of wavelength to energy. But x and γ wavelengths are several oom shorter than visible light, so you'd have to be traveling at very close to c to experience that amount of Doppler shift.
It depends on acceleration though. If acceleration and deceleration take long enough, it could take an entire generation to get up to a fast enough speed that relativistic effects make any difference, and another generation to slow down enough to interact with anything you might see.
Plus if you're traveling at near light speed, running into any matter at all would be pretty devastating for whatever craft you're in.
Edit: someone further down claimed that the math says that accelerating at 1G would get you to 0.1c in a month, so that's actually not that bad all in all. I still maintain that hitting any matter at those speeds might be unpleasant.
But unless you have a way of slowing down again you'll never see anything of your destination, just the briefest of flares of light as you sail past. And if you do have a way that involves anything like physics that we recognise, you've brought along a huge rest mass that then got accelerated to near light speed. Probably your civilization needs to be approaching Kardashev Level 2 to pull this off.
One thing I've always wondered is what fraction of c is actually realistically achievable with current technologies? (Maybe with scenarios for manned/unmanned spacecraft.)
Like are we at 0.1% or 0.01% or more orders of magnitude off?
The best speed for interstellar travel with technologies that current theory says should be within our reach can be achieved with a vehicle with a light sail pushed by a giant laser, that is powered by solar power. There is even a way to brake it when it reaches the target star. I forget what the predicted velocity was though.
This technology is basically the same as one that the Moties developed in the story, The Mote in God's Eye.
It slows down by releasing a large light sail in front of it, designed to reflect light back to a much smaller light sail behind it. The laser then pushes the large sail away, and as the sail goes it pushes the smaller sail (and ship) back. This leaves the ship at moderate speed relative to the new star, and a large sail traveling very, very quickly beyond it.
We do not yet have this technology. But we can show that it is plausible.
First set gamma as being 1/sqrt(1-v^2/c^2), with "c" being the speed of light. The factor for time dilation and distance contraction in special relativity is gamma and 1/gamma respectively.
That means that when you get to speeds equal to c, your time runs infinitely slower and the distances are infinitely shorter. So if your clock is infinitely slower, so every travel at "c" speeds means that no time passes for you. And if your distances are infinitely shorter, all travels at "c" speeds cover any distance as immediate. So you could reach every point of the universe as if it was immediately closer and in no time at all.
So in the frame of reference of the photon, the moment it is created it has already reached its destination, be it wherever it is on the universe.
Of course we can never reach "c" as beings with mass, but we can get closer to that. So for example if you get to 99.99999999999999% of the speed of light, you could travel a distance of 54,794,520 ly and only one year would pass to you, while 54,794,520 years would pass on earth.
Follow up question from someone who's mostly forgotten his university physics.
Do photons actually exist, in the traditional sense of physical matter.
Or are they just a convenient short hand to describe the transfer of energy via waves in the fabric or space time, if they dont experience the universe when passing through it but only when interacting with matter and matters "dents" in space-time.
As a non-physicist, my understanding is that they actually exist, but can't be thought of as flying around like ping pong balls. I think it's one of those things that comes down to interpretation though, where the math is very clear but how you think of what it "means" lies beyond science.
That doesn’t make sense - if you were traveling at the speed of light, it would take you 5000 years to travel 5000ly - longer if you were just ‘very close’ to C. Time wouldn’t advance slowly for you, it wouldn’t advance perceptively different at all - you’d still live every second of those 5000 years.
I dont think you are right. Light for example doesnt perceive time at all. From the photons point of view it never aged even a microsecond while it traveled lightyears. Time is relative too so from our POV 1 year passed when a photon traveled 1 ly, but for the photon no time passed.
You two are talking about different meanings of "time".
Traveling 5,000 LY at 0.5 c will cause you the spaceship pilot to age 20,000 years. It's non-relativistic, inside that inertial frame. Clock second hands still sweep slow but noticeable circles.
Meanwhile, everyone outside of the spaceship is happening FAST, by your observations. You'll see stars turn red and go supernova.
Doesn't this depend on the initial distance to the destination? I'm thinking you have to be going ~140M light-years for cosmic expansion to exceed 1%c, and Proxima Centauri is only ~4 light-years away
There's nothing about 0.1c or even 0.999c travel that's detrimental to meatbags. They would both feel exactly the same to the traveler. If your (for now) imaginary rocket could accelerate at a constant, gentle 1G, you could reach 0.1c in about a month (traveler's time), and you could reach 0.999c in about 44 months. Building and fueling such a rocket is the hard part.
It depends on how you define the bounds of the Solar System, but eg. a flight from Pluto at its most distant to the same distance on the opposite side of the sun that hits .1C at peak needs ~5G for the entire duration. And it seems quite wasteful to bother getting up to speed before immediately reversing the acceleration.
If you're travelling between points in the Oort Cloud, 1G should be more than sufficient to hit .1c on the trip.
My point was that the GP talked about flight times assuming instantaneous acceleration and deceleration. Also, 1G of acceleration sustained over a month is more or less impossible for meatbag-sized spacecraft, especially if you need to also accelerate all the fuel you’ll need to decelerate. The rocket equation is simply way too brutal. Something like nuclear pulse propulsion might come close. Or antimatter propulsion if we’ll ever be able to create and store entire moles worth of antimatter.
Assuming our models of the universe are correct, and faster than light travel is impossible. There are very strong reasons to believe this, but perhaps we can cheat by stretching and compressing space around us.
It makes me wonder what kind of "life" could perform interstellar travel? I used to imagine a spaceship being alive, with people inside being analogous to "cells" in a multicellular organism.
Perhaps this is really how AI achieves consciousness?
To make a generation ship work you have to build a self-contained ecology that is stable and self-repairing, inside mechanical and software systems that are fault tolerant and either extremely redundant or self-repairing, run by a political and social system that is also fault-tolerant and self-repairing.
More to the point the ship needs to be absolutely self sufficient, it can't even use solar power and has no access to outside mass whatsoever. But if you have a ship like this you could build an orbital habitat using the same technology, and it would be much much easier to build since it doesn't have to accelerate, can use solar power, and has access to the rest of the resources of a solar system.
If you have all of this why would you go to the enormous extra effort to move the habitat to a different solar system? Even if your civilization is so old that the star is a dim brown dwarf that's still plenty of energy for day to day life.
There's a CRPG I've been meaning to play where this is basically the plot; there was a generation ship, it was heading towards some planet or another, but the social and political structure on the ship broke down at some point and now there's no one actually in charge, the ship is getting run down, and they probably blew past their destination a hundred years ago if they were even still on course at all.
I remember someone pointing out that a generation ship could be problematic because you have one generation who decides to launch this expedition but will never see the end, multiple generations who didn't choose this life and won't get to see the benefits, and then one generation who actually gets to the planet but might not even want to be there. Without some kind of cryogenic sleep or relativistic speeds the whole thing might fall apart just because most of the people involved "didn't sign up for this" but they have to toil away anyway for someone else to benefit from it.
What of the "just so" attitude of a child growing up? Everything is taken at face value, there is no comparison, only stories (unless you have a catalogue of 30EB of 8K earth footage or something to that effect for them to fawn over). They don't have the reference frame for other situations for a while, perhaps long enough to not be able to see things differently?
This makes me think of multi-generational migrations north out of Africa. There's only so much that can be passed orally losslessly. Eventually the group in north siberia after 20K years doesn't see living any other way.
> I remember someone pointing out that a generation ship could be problematic because you have one generation who decides to launch this expedition but will never see the end, multiple generations who didn't choose this life and won't get to see the benefits, and then one generation who actually gets to the planet but might not even want to be there.
That isn't really different from the way things are now. We are, in fact, traveling through the galaxy for many generations and none of us signed up for it. We just happen to be on a largeish ship and have no destination.
Well, to be frank, we currently have such a ship, but we're doing quite a lot to disrupt its capability of sustaining human life.
Of course, even if we stopped doing that, we'd need to figure out how to visit another place if our ship is passing close by. That also seems to pose a problem: both Voyagers are barely out of the exhaust fumes of our ship's motor, and getting so far took ~40 years.
It's a wonderfully entertaining book and for that reason I loved it, but Andy Weir really, really glosses over and hand-waves away all kinds of other difficulties for so quickly and easily building a ship that can travel at nearly the speed of light.
He basically just has it work because the fuel difficulties are solved and bam, the main character can zip around nearby start systems at close to perfect C on a ship built with little more than our current 21st century technology. Fun, but not even in the most basic way an attempt at presenting any science seriously.
What makes it more amusing is that for many other parts of the main drama, he puts a lot of effort into making the descriptions and scenarios seem as realistic and science-rich as you could like. I suspect a lot of entertaining word salad there too though.
I would say they're two sides of the same coin. The time it takes for light to travel the universe (which makes communication even with nearby stars essentially impossible) is what makes the universe huge.
SR breaks down at both ends of the spectrum, at the event horizon of black holes and in Bose Einstein condensates. That proves that it is an emergent property of observations, statistical behavior of decoherent systems, and not a universal law.
Depends on who you mean by we. The universe is weird and it's entirely possible for you or I to travel essentially arbitrarily far in a single human lifetime, easily billions of light years. Relativity doesn't simply work as a speed limit; instead when things approach velocities anywhere near the speed of light, the universe starts contorting itself in really weird ways to maintain the perceived consistency of the speed of light.
From the perspective of somebody in a ship moving at relativistic rates, distances would begin to physically contract, and time itself would begin to speed up relative to an at rest observer. Here [1] is a calculator to see what this all mathematically works out to. For instance, you could travel to Andromeda, some 2 million light years away, in about 28 years in a ship that was capable of sustaining acceleration at 1g for 28 years. Of course for everybody back home 2 million years would pass. So if we ever achieve ships capable of this sort of acceleration, life is going to get really weird and non-linear, so far as time is concerned.
And this isn't some just some weird fringe theoretical/mathematical thing. For instance GPS satellites have to compensate for time dilation because relativistic effects, though small in this case, would otherwise have a substantial effect. Another example is at things like the large hadron collider. As a convenient effect of relativistic effects, emergent unstable particles exist far longer than they 'normally' would before decaying due to the fact they're moving at relativistic rates.
In other words, this is all very real. The only questionable issue is whether we can discover some sort of an energy source capable of accelerating a ship at 1g for tens of years, and develop sufficient shielding for such a vessel. That's still very much in the domain of sci-fi, but simultaneously seems like something that one wouldn't be entirely surprised to see was discovered just a century from now. This was the most tantalizing possibility behind the EMDrive stuff. [2] Well that or infinite energy, but it seems that universe won't be broken quite so easily just yet.
True but doesn’t matter how slow light is. The closest to c your speed is, the shortest the time you experience on board of the space ship. At light speed, space and time cease to exist. You reach destination instantly.
So the goal is to create engines that can take us close to light speed. Then the issue is braking (spacetime expands as you slow down…)
Its relative! Sitting on a couch and watching the pixel move from the sun to the earth for 8 minutes feels incredibly slow but if you are actually traveling in a light speed aircraft then it won’t feel that slow.
If you were actually traveling at the speed of light it wouldn't feel like anything at all! Photons don't 'experience' time—any length trip would be instantaneous from the traveler's point of view.
Quite the opposite, much like when skydiving, going really fast without any close reference point makes everything stand still. And in space, there wouldn’t even be (very loud) atmospheric drag to physically remind you about what speed you’re actually going.
I believe the OP was referring to relativity - the closer to the speed of light you get the slower time appears to tick. So if you could travel at light speed you'd arrive at your destination immediately from your reference frame, but much slower from another person's.
1) it's better for the plot and drama to have travel time. FTL in fiction is always analagous to some known terrestrial form of travel (usually ships and boats) and the limitations and parameters of FTL in a fictional universe shape the narrative in necessary ways.
2) it's assumed within the framework of the fictional universe that time dilation isn't taking place because the actual travel is occurring within an external frame of reference like "hyperspace" or a "warp field."
Amazingly, yes, in a few ways (the mechanics are possible). But no in as many ways. (Fuel, sustainability, tracking)
The greater barrier is that the nature of the expansion of the universe prevents any real interstellar travel that has a "destination" in mind. Of course we might have some "FTL" or "near light speed" travel in futre, but if the universe is expanding infintely from every point in space at light speed, how could we ever "catch up" to objects we see even now?
If your travel involves the Rocket Equation the answer is no. If you are limited by the speed of light and the lifetime of human civilization then the expansion of the universe is not an issue. Traveling between nearby solar systems is very close to impossible, traveling between galaxies is outright impossible.
The lifetime of human civilization problem is an odd one, because due to relativity, one-way trips are not an unsurpassable hurdle ( 2-3 generations on a 1 G spacecraft to get pretty much anywhere). But you can't come back, because it's basically guaranteed there'll be nothing left for you to come back to. Because while it might take "only" two hundred years from the passengers perspective to reach the edge of the (current) observable universe and come back, they'll be arriving 90 billion years in the future.
The objects you can (eventually) reach are proportional to your speed. For example at half light speed you could catch up to objects nearly halfway to the Hubble Horizon, about 7 billion light years away.
This is not true. Expansion does not affect gravitationally bound structures. Our galaxy, and even the other galaxies in our local cluster, will stay in reach.
Not naive at all. With chemical rockets we can only sustain 1G for a few minutes, so it won't do at all for interstellar flights.
There is a known way to achieve 100% fuel efficiency: antimatter. By storing equal parts matter and antimatter, you can fuse them to propel your spacecraft. It's unknown wether or not this kind of engine can actually be made.
Alternatively, and even more far-fetched, you could onboard a small singularity. Dumping anything into it will result in it being turned to pure energy at 100% efficiency, through Hawking's radiations. The smallest the singularity, the fastest it radiates, meaning you can sort of control the output. You can create singularities with very large particle colliders.
With 100% fuel efficiency you can probably sustain 1G for long enough to reach the nearest stars. You would need a very large spacecraft (on the order of kilometers) for a comparatively very small payload. And it would arrive completely empty at its destination, meaning no turning back. I think I saw someone do the math, but can't find it anymore.
Anyway, there are other difficulties. Travelling at .99c means tiny space dust now becomes very dangerous. So does radiations, all made extremely energetic by the Doppler effect.
On the plus side, continous 1G means you have artifical gravity for the whole trip.
Well, if you were traveling at light speed you could move anywhere in the universe instantly. If you are an observer on earth, watching an object move away from you at the speed of light, then it will take a very long time to traverse the tiniest regions of the universe.
even in a vaccum, light speed travel from the travelers POV still takes time, and said traveler would perceive time passing exactly as occurring in that local space.
But yes you're totally correct, the observer on earth would in this time see only the briefest part of my journey's trail due to light from my journey taking "exponentially" longer to travel back to the observer.
Exactly, there is free fuel and aluminium just floating by, and we are unable to use them to upgrade our ships or refuel them.
Until we make full use of robotics and 3D printing, there is no point of heading far. And we have all the tools.
Distant stars will not be settled by a fast small ship travelling from earth. They will be settled by a city sized monolith produced by harvesting and smelting an entire small moon
> Distant stars will not be settled by a fast small ship travelling from earth. They will be settled by a city sized monolith produced by harvesting and smelting an entire small moon
I don’t even think you’d need a whole moon unless it was a tiny one. Nonetheless, by the time we send a ship to another star, building these kinds of large self-contained habitats will be old hat.
Stephen Baxter wrote a story named The Gravity Mine about the descendants of humanity living after all stars have died. They get energy from black holes but even they are starting to noticeably shrink. Their perception of time is billions of times slower than humans and the upshot of this is that the speed of light would actually seem pretty fast.
All of fiction and discourse fails to consider that the Solar System is actually a huge place and just the period of settling and industrialising it will take hundreds of years.
Everyone things that a game breaker technology is better engines, or fusion, or FTL, but they are wrong, the game breaker technology has already happened: 3D printing.
If we can manufacture things with minimal infrastructure using local resources, we can that is all we need.
And all of it reachable with simple nuclear power and technology we have today.
you would need a ship that is also a city. a traveling space station. or probes. if humanity decided to send a small probe to the nearest foreign star, i wonder how many km/h current infrastructure could accomplish
This seems like a browser issue more than anything else. Yes it's "weird" to have millions of pixels horizontally on a page that is only a few thousand pixels tall, but it seems like an absolutely reasonable edge case that the browser should support.
The red bit is the sun. 1000 kilometers per pixel, and 1000 seconds per second.
They all fit onto the screen by looking through the orbital plane, as if through a telescope from a distant world, i.e effectively an orthographic projection. The orbits are accurate in terms of mean orbital distance (in reality there is slight perturbance) and sidereal periods.
You mean technically? I should have posted the beta dwitter link which has the "compress" toggle, because most dweets are unicode packed. https://beta.dwitter.net/d/26521
This one is actually relatively simple to explain, it loops over the 10 planets (i), and draws a circle for each, with the position and size all being defined in the x.arc method. Planets are differentiated by the arrays of values selected by [i]. The X position is calculated as the orbital distance multiplied by the sine of time / orbital period... d x sin(t/p). But d and p are substituted for the value for each planet using the arrays [1,2,3][i].
Surprisingly the precision used in those encoded values is enough at 1000km per pixel (I checked).
I presume including Pluto's parameters in the array is both a rebellious statement and a brag. ("Yes, my JS snippet could have been even shorter if you asked the IAU.")
Actually I couldn't fit Pluto, I sacrificed everything I could, but to fit it would require sacrificing the precision of Mars, Earth and Mercury (dropping the decimal), but I wanted to maintain enough precision to be able to tell them apart by size (which you just about can at full screen due to antialiasing)... Otherwise I definitely would have included it for that very sentiment ;)
The reason there are 10 radi is for 8 planets + sun + drawing the black backdrop (2e3): [24,25,58,69,3.4,6.4,6,2.4,696,2e3]
I remember back in elementary school, way before we had such things on computer, we had a vinyl roll for the age of the planet. You'd roll it out in the hallway, starting with present day and watch as the different time periods came into view. You were just a few feet at the origin of man, at the end of the hallway by the time you got to the beginning of Cambrian era, and out the door and across the huge athletic field before you got to the formation of the planet.
Still an extraordinary experience after all these years and possibly the best use of horizontal scrolling I’ve seen. Lots of previous discussions and posts on HN:
https://hn.algolia.com/?q=if+moon+only+1+pixel
When I was dabbling with POV-Ray many moons ago, I drew the planets of our solar system to scale with it. You can see it here: https://github.com/susam/pov25#planets
A friend once asked if I couldn't show the planets in orbit rather than lying flat on a plane. I could, of course, but this is ray tracing. What do planets actually look like to human eyes from Earth? Just tiny dots.
If I were to show them in their proper orbits at scale using perspective projection, I'd only be able to render one planet large enough to be visually interesting. The rest would appear as small dots. I didn't want to use an orthographic projection, as it wouldn't reflect how we actually see the universe.
Those were, of course, limitations of a still image. An interactive page like the one in the original post does a fantastic job of conveying the vast scale of our solar system, both in terms of the sizes of the planets and the immense distances between them.
Would you have to use double precision to ray trace the planets in their proper orbits at scale using either perspective or orthographic projection? With the ratio of Neptune’s distance from the sun to its radius being almost 2M, I’m guessing fp32 rounding would turn Neptune into a couple of squares if the sun was at the origin. What other challenges would there be? Maybe I’ll try it today just for fun.
The light speed toggle really hammers home the emptiness. Like, I know that the Earth is ~8 light minutes out, but sitting and waiting 8 minutes for a few pixels to appear when scrolling away from the sun…
I've seen several, Planet Trek in Wisconsin is a good bikeable one with high quality signage. The sun is downtown, the moon is the size of a peach pit, Pluto is ~20 miles away.
Given the great distances and how small the planets seem at that scale, I'm surprised that we can see any of the planets with the naked eye. Thinking about Jupiter, it's 140K km in diameter and about 629M km from Earth. That's a ratio of 1:4500. So imagine a U.S. dime that is 1.8cm in diameter placed 1.8 x 4500 = 8100 cm away. Would you be able to see a dime that it 81m or 266ft away at nighttime, assuming it slightly illuminated? We can see Jupiter, so I guess we should be able to see the illuminated dime too.
I've seen countless analogies that explain the size of space, but this was really something else. Especially how frustratingly slow the speed of light felt.
It's a hands-on, practical example of how far things are away that we can easily visualize. I highly recommend the rest of the series as well. It's one of the best science shows ever produced. It shows the practical path of scientific discovery. You can watch is on the PBS app, which requires a $60 a year pass. Highly worth it. (I have no affiliation with PBS)
Interestingly, that Hawking visualization makes all the same affordances mentioned in the 1 pixel visualization. They show the earth and moon to scale, then the video shows an aerial view with all the planets much too large. Jupiter is 2x the size of the sun. Saturn and its rings 2x that.
Sun diam 1,400,000 km
Eth diam 13,000 km
Sun dist 150,000,000 km
Mon diam 3,500 km
Mon dist 300,000 km
Lets divide it all by 1M. So if the sun is 1.4m in diameter, it would be located 150m from earth which would be 13mm in diameter and the moon would be 3.5mm located 0.3m from earth
Simply put, imagine a yellow beach ball the size of a washing machine located a block and a half away from your house, a blue marble being the earth on one side of your keyboard and a peanut being the moon on the other side
Now, using the basketball 24cm (earth) and tennis ball 6.5cm (moon) comparison, they would be separated by 7m in your living room and the sun would be 13m tall (a cherry tree) located at 3km from your house
One thing to notice is how small Mercury is, only 1 pixel like the moons that show up. Here's a good photo size comparison. Mercury is smaller that two of the solar system's moon!
Unrelated, but the Elon dream of getting a human colony on Mars seems beyond imagination. Ignoring safety of such a long travel, the radiation issue of Mar's surface, and the massive infrastructure to have a self-sustainable biosphere (also somehow protected from radiation) to recycle enough oxygen, we still have to deal with the immense number of failures that could happen with no way to send help.
Like, building a fully self-sustainable underwater city or moon base would be far more in reach. It feels that SpaceX should start with prototyping these safer alternatively before overreaching to something 100x more challenging and dangerous.
> Like, building a fully self-sustainable underwater city or moon base would be far more in reach. It feels that SpaceX should start with prototyping these safer alternatively before overreaching to something 100x more challenging and dangerous.
I've been beating this drum for years. Elon is 100% focused on building the rocket that can get to Mars and neglecting absolutely everything else about the project. Where is the self contained biosphere pilot program on Earth that tests the Mars habitat? To be anywhere close to Elon's timetable it needs to be running today, and honestly it should have been running years ago. Given the extreme reliability requirements it needs long term testing to build any confidence at all in the numerous technologies involved. The closest model we have is the ISS, and it's mostly shown that we aren't ready for a Mars habitat. The ISS requires way too much maintenance and ground support.
The problem with Mars is that if something goes wrong you can't just "fly back on the rocket". The launch windows are 2 years apart. You either fix it in place or you die.
At least theoretically it should be doable. But I think it will be similar to the moon landings. My prediction: People are going to lose interest in the project very quickly. It will be prohibitively expensive to maintain and there is simply nothing to do. You couldn’t even really have a remote programming job there. A light round trip takes between 6 and 44 minutes, completely unsustainable.
If you're really interested in a deep dive on this subject then I really recommend "A City On Mars" by Zach and Kelly Weinersmith (of SMBC). It goes very deep into things like - can you have babies successfully in space?
It's very clearly not "beyond imagination". It doesn't require any fundamentally new technology.
It may well be beyond our ability to practically apply those technologies at the required scales and reliability levels, but that's hardly unimaginable.
I believe the scientific record is drawing a consensus on this as the moon's origin but the wild sparseness of space just makes this sound really unusual.
We’re never going to leave this planet/solar system if we don’t discover FTL (Faster Than Light) travel. Pretty scary if you think about how ridiculously empty is space.
Alpha Centauri is a triple star system with no habitable planets. Why in the hell would you go there? Sending people to another solar system is so resource intensive that assuming you can convert the entirety of Jupiter into some kind of orders of magnitude more efficient exotic rocket fuel you might have enough resources for a small handful of expeditions, so you really need to make them count.
Maybe it would make sense if you could convert the mass of Proxima Centauri into rocket fuel to fund more expeditions? That seems like a fairly long term plan though.
I mean, why did we go to Mars without any intention of colonizing it? The Moon?
Exploration is what humans do. If Alpha Centauri is only 5 years away, you can bet we're sending people there no matter what. Permanent colonization only becomes a priority in an existential event, and if we eventually achieve ~1.0C travel then that implies our tech is at a level we'd be colonizing Mars and a few moons long before we think about leaving the solar system.
Even getting to 0.9C is going to be very very hard for humanity.
I've always thought that people pushing for colonization or even commercial exploitation of space simply don't have a good sense of how far things are and how empty the space between us and those things are.
That has always been the case, there is loads of empty distance between big population centers even today there are big cities many hours by flight from anywhere else of interest.
In the age of sail, people were perfectly willing to spend months in transit .
Transit times for most objects of commercial interest (i.e. upto moons of Saturns) is only in years if you use a low energy/Delta-v Hohmann transfer orbits and/or gravity assists as is common today for probes.
Direct transfer would be expected for human transits , those can be fairly quick . Transfers to mars within the next 1-2 decades is doable in 6months or less.
There are no fundamental breakthroughs needed to go any orbits we would be interested in 1 year or less by end of this century.
On the other hand I do agree going interstellar is a whole different scale of empty and without near light speed (even with ) is probably out of reach .
I’ve been thinking about how to teach the size and proportions of the solar system to my kids, I’ve bought a couple of packs of blank RFID cards on which I intend to paint the planets over a starred background. And then walk with my kids the meters necessary to cover the distances before displaying them. What I don’t know is if there is a clever way to use the RFID tech, this website kinda offers an idea.
This is a great website—it reminds me of To Scale: The Solar System [1], a mini-documentary where people attempt to build a true-to-scale model of the Solar System. It makes me feel like a tiny speck of dust, floating in the vastness of nowhere...
Look I'm no astronomer, but I'm pretty sure celestial bodies all have elliptical orbits, so if you're going to label something as 'tediously accurate' you should give some indication that the distances from the sun are changing over the orbital period.
Didn't have the patience to read the fine article? Understandable I guess, but I thought it was worth the effort. Quoting from it:
> All these distances are just averages, mind you. The distance between planets really depends on where the two planets are in their orbits around the sun.
I've seen models like this before. We live in a universe with many, many orders of magnitude. In both directions. Living creatures to small to see, space too big to comprehend.
Mining asteroids for space resources sounds great, right up until you consider the distances involved. Living on Mars - yes, we really should - but you sure aren't going to support a colony long-term from anywhere but local resources.
We are pumping oil that's located under the seabed. It would have seemed completely insane in the 19th century when all oil was easily accessible. Asteroid mining might be feasible in a few decades. If it really gets going - it could make gold as cheap as aluminium is today.
This is super cool. It's crazy to think about asteroids in any depiction of the solar system look so packed that I thought a spaceship would never be able to pass through unscathed, but here it's all black because they are basically irrelevant lol
Also crazy how far Jupiter's gravity can keep a moon??
Importantly, the planets aren't actually lined up nicely like on the site. Right now, Mars is ~5 times further then shown.
That's why so many people were taking pictures of Mars back in January, when it was actually possible to take see detail. Right now it just looks like a red orb.
This is truly marvelous! Not only is the horizontal scroll really extra awesome for making me feel the distances...but as others stated, the moment you toggle on the light speed....wow, it really is quite profound! Amazingly done!
How does this website work? I feel like I'm stuck on the first screen maybe? It says 'scroll to explore' but there are no scrollbars. Does it only work with a mouse with a scroll wheel?
I love it, I always love these things. Still, given this is a technical site, one small nitpick is that it would be nice on hover to see how many pixels the current object is.
There was a plan in ~2016 backed by Zuckerberg, Hawking and some entrepreneur but it didn't really get anywhere (in a literal sense). Research for it stopped in 2022 because of a "lack of funding".
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
Make sure you press the "c" button in the bottom right.
Light is incredibly slow, and everything seems out of reach.
I think we'll have a holodeck before we reach another star. And maybe that'll be enough.
Is light slow? Or is the human perception of time just scaled down as a result of our rapid metabolism and infinitesimality? People historically mistake plants for being inanimate things with no reactivity, that they are far more simple and stupid than they truly are. Outside of a few exotic examples, plants simply operate on a wider timescale that's basically imperceptible without careful and particular observation. It becomes much more apparent how alive plants are when we observe them in a time-lapse. Now realize that plants are still relatively short-lived. The absolute oldest ones only go back to the early neolithic, that's only 14000 years or so. 1000 years is a long time for humans, but probably not for the trees where a single one can live 10x that.
From the hypothetical perspective of a star, with a lifespan measured in billions upon billions of years, the entire ecoscape of the world changes in a blink. From the sun's perspective, MENA was green just a very short while ago. Hell, Pangea wasn't that long ago. At this timescale, continental drift would be as apparent as the movement of boats are to humans. Anything that's working at the cosmic scale where the seemingly low speed of light sounds exhausting is most definitely working at this stellar perspective at the minimum. 14000 years of travel might as well be the equivalent of a 10 minute commute to the store.
Philosophically speaking, of course.
Light is comparatively and objectively slow in comparison to the distances that exist. Andromeda is 1M light years from us. From that perspective, 300k kph is oddly slow actually. I love the passion that you're brining to the table though. It reminded me of the blue giant stars whose lifespans can be as short as tens of millions of years, more often hundreds though. For billions upon billions, I suppose that would be white and brown dwarfs. Although, if we could orbit black holes and harness the energy of gravity, then we're really talking long time scales. Cracking the aging problem would allow us to think in very long timescales. But I do wonder whether the human psyche could handle such long lifespans.
> in comparison to the distances that exist
This leaves out the time component. Who's to say that a year is long? A galaxy a million light years away takes a million years to reach... and maybe that's a short amount of time, to the right observer.
Light could only go to Andromeda and back 1000 times before the sun burns out. That's not very many times IMO. On the scale of galaxies, light is slow relative to any timescale relevant to large objects.
Carrying the metaphor further, that's closer than America was to Europe in the 18th century.
How many times can you go from Lisbon to Beijing and back by car in your lifetime?
Not many, because cars are slow
There's a great video is saw. In 30 minutes it goes through the entire lifespan of the universe.
Even after all the stars die, the white dwarfs will continue to glow. And after eons, the last black holes will evaporate. The point is that the age of stars is only a tiny fraction of the lifetime of the universe. Maybe the speed of light makes sense at that scale.
But... I'm not happy with that theory. In a relatively short amount of time the expansion of the universe will increase faster then the speed of light. Which means it will be impossible to ever get information from the other side of the universe.
I find it very unreasonable that the universe imposes a speed limit on everything and then completely ignores it.
Thanks for this.
In addition to the insight, it reminded me to water a plant at a desk I no longer use. The plant's been with me through quite a bit and I have been neglecting it recently as I no longer see it regularly.
Move your plant friend to your new desk?
In turn this reminded me to water my terribly neglected office plant, so thank you!
For very philosophical writings about this, read "Last and First Men" and "Star Maker" by Olaf Stapledon. Written in the 1930's, these describe on a very expansive scale the history of, respectively, humanity and the universe. Very mind bending.
I always think of those motor proteins moving along slowly inside our bodies, and wonder if maybe we are just the motor proteins of the cosmic scale.
We have a long way to go before we learn to move a star (or a rosette).
https://en.wikipedia.org/wiki/Stellar_engine
https://en.wikipedia.org/wiki/Klemperer_rosette
Dude, pass the duchy.
yeah light _is_ actually pretty slow and we hit that in networking and optics pretty often if iirc.
like not even on a human level, universally even on a grand scale the speed of light is almost torturously slow, there’s nothing philosophical about it
Might have been a deliberate rule enforced on the universe to avoid interstellar wars between sapient civilizations.
But that’s making your simulation deliberately less interesting, no?
Chances are that only a species who, through one way or another, has become very uninterested in warfare could have advanced to the point where they would be able to run such a simulation, otherwise they'd have ended their own existence with their shiny toys before long.
War only occurs if you have in the literal sense retarded elements in your advanced species and is nonsensical from an outside POV. A species this advanced would have fixed such shortcomings in itself long ago.
So no, I don't think they'd necessarily be very interested in watching primitive species go to war with primitive weapons.
For all we know the simulation of this universe is happening in their equivalent of an overengineered snow globe, us being an artifact nobody has noticed and that nobody would find particularly interesting if they did notice.
something can only be "slow" relative to something else. it's not an intrinsic property.
At the moment humans only live ~90 years which is a blip in cosmic terms, but shortly we should be able to merge with AI and live for billions of years and visit stars.
> Is light slow?
It’s always faster than you or I. Even if we zipped around at relativistic speeds it would still appear the same.
Comments like this are part of the reasons I come here.
humans are a blip. i think the overwhelming scenario is we were a bootloading sequence for silico sapiens.
That’s one of the answers to how you could go to the stars: go sloooooow as in slow down your cognition and metabolism so the trip doesn’t take long.
Ents could fly to the stars no problem.
Makes me wonder if there might not be a bunch of star faring “slow life” out there that we don’t notice for the same reason a hummingbird doesn’t notice trees growing.
> Is light slow? Or is the human perception of time just scaled down as a result of our rapid metabolism and infinitesimality?
It's slow for humans to explore the cosmos.
"Slow" is meaningless without a frame of reference, and "humans" seems like a good frame of reference, since it's us -- and not plants or stars -- who are writing on HN to discuss this.
Because it's us, humans discussing this in HN, the frame of reference is implied and it's not necessary to spell it out.
It only seems incredibly slow in this model because it doesn't take special relativity into account. If it did, then as you approached the speed of light the Lorentz contraction would make wherever you are heading appear less far away. You can in theory get anywhere in the universe in an arbitrarily short amount of proper time your own reference frame. Of course, you might not survive the G-forces, but that's another matter.
Don't forget gravity drive. No more Gs. And the same technology would give us real artificial gravity, not this nauseous rotation artificial gravity.
You can accelerate continuously at a comfortable 1g and get to 0.5c in about 5 months. G forces are not the issue.
The Lorentz factor at 0.5 c is 0.86 so this only reduces your proper travel time by about 15%. Even at 0.9c the LF is only 0.43, so it would still take you 2 years just to get to Proxima Centauri. And as you approach c, 1G acceleration speeds you less and less. And you also have to slow down at your destination.
Not to mention that you also have to survive any collisions with specks of dust in between.
> Light is incredibly slow, and everything seems out of reach.
Yes, agreed. I find it a little depressing. An unimaginably huge universe, tantalisingly there, but completely out of reach.
Not out of reach if you get very close to light speed. Time would advance very slowly for you, so counterintuitively it is possible to travel 5000ly in your life time.
Although for everyone else at least 5000 years will pass, so better say goodbye to family and friend.
Hm, not sure if that is really less depressing...
Also light isn't slow. A photon instantly travels to the end of time and yet it still takes a few minutes from the surface of the sun to us. Or about 100000 years from the center of the sun to its surface.
Yeah if you have a body that can tolerate sudden jumps between reference frames you could pretty much explore the entire galaxy trivially, so long as you don't mind that few places will stay the same long enough to visit twice.
You wouldn't need a sudden jump. If you had a rocket that accelerated at a pleasant 1G forever, you could reach and stop at the center of the milky way in about 20 (your time) years, and you could reach and stop at the Andromeda galaxy in about 28 years. Play around with some of the online space travel relativity calculators--it's wild!
Of course building and fueling such a rocket is what's totally out of reach.
> Of course building and fueling such a rocket is what's totally out of reach.
We'd need a device that could efficiently transform several kg of matter to photons.
Also some kind of a energy shield. Space is pretty empty, but if you go fast enough, you will still hit lots of non empty space.
And back?
Is there drag in space? I.e. would you need increasing energy to accelerate at a constant rate as the speed goes up?
With a traditional rocket, I believe you'd need decreasing energy to maintain the same acceleration as the flight progressed, since you are carrying along with you and burning the fuel, and so the total mass (payload + fuel) that needs to be accelerated is constantly decreasing.
Of course there's the pesky problem that for every N kg of mass you want to accelerate at 1G for that kind of a trip, you're probably going to need somewhere on the order of N billion kg of fuel to burn.
I guess one assumes that whatever system prevents you from getting hulled by space dust also removes the drag from the equation?
> Hm, not sure if that is really less depressing...
A starship capable of such a journey is surely large enough to bring all your friends and family along, colony-ship style.
We're already on that starship. Our engine is about 8 lightminutes away. All we need is to figure out how to steer this thing - and how to not wreck it while en route.
I would prefer the concept of people building an artificial planet/asteroid/spaceship for a starship, instead of messing with our star system. But luckily that debate is some years away and currently we cannot even figure out, how to deal with some increased CO2 levels.
How would that feel as a traveler? Does all motion slow down to a crawl, all sub-atomic particles just "freeze" and essentially your thoughts and body aging too? So it would seem like you got there in an instant?
For sure you're not just sitting there watching people get born, live and die in second and shrugging your shoulders.
You’d feel nothing out of the ordinary whatsoever. The starscape outside the ship would look strange though, shrinking into a small, blueshifted patch of sky straight ahead, while stars behind you would redshift out of the visible range. Everything moving at very low speeds relative to you would indeed appear to happen really fast.
What are the chances of hitting a small meteorite or part of it, traveling now at relativistic speeds wrt you?
There's about one particle of dust per million cubic metres. c is about 300 million metres/second. So even at 0.5c that's still a lot of particle collisions per second, each having significant kinetic energy.
Basically it would be like flying through explosive sandpaper. Each dust particle would be reduced to plasma, which creates problems of its own.
If you're accelerating there's also the Unruh Effect, which will raise the perceived temperature. By a lot.
There's no way to make this work with any kind of engineering we know about today.
The Unruh effect is theoretical, and no evidence at all has ever been found that it's real. It literally exists as nothing more than a hypothetical mathematical model, that also happens to be debated by others who know enough to effectively debate it, and disagree.
Micrometer-scale specks of dust would hit you like they were armor piercing tank gun rounds. The usual shielding proposed is ice. Lots of ice.
Why ice?
Mostly that it's plentiful, ablative, expendable, plus good radiation shielding (yeah, cosmic ray protons are really going to mess things up at relativistic speeds too unless there's enough mass to stop them).
Extremely low. Space is very empty.
It's one of those cases where you have very small numbers multiplied by very large ones. The actual risk is hard to intuit because there are so many orders of magnitude involved in both directions.
In any case it's probably a moot concern as long as we are living under the twin tyrannies of Newtons Third Law and the Rocket Equation. Building a rocket that can accelerate constantly and noticeably for weeks, months, or even years on end in order to accelerate up to a velocity where Relativity starts to matter requires an absurdly large rocket. Like converting the mass of Jupiter into rocket fuel to make it to the next habitable solar system in a couple of centuries level of craziness.
Micrometer-scale dust particles would in fact hit you all the time. And they’d absolutely mess up your ship over time without a lot of shielding.
But it's also very big, and GP doesn't even specify how far of a trip they're asking about nor how small a meteorite.
"Extremely" and "very" don't cut it here. This is beyond the human ability to guess. You'd actually do at least some back-of-the-napkin math to give a real answer, and with a far enough trip, the answer may well become "Almost 100%".
How far a trip: maybe start with the nearest star.
And at a high enough speed, the impacts from the ~1 hydrogen atom per cm^3 in interstellar space become a major problem.
zero if you hit that spice first
If the light behind you redshifts out of the visible spectrum, would the light in front of you blueshift into dangerous territory? X-rays, gamma rays, etc?
Yes, and this provides a nice intuition about the relation of wavelength to energy. But x and γ wavelengths are several oom shorter than visible light, so you'd have to be traveling at very close to c to experience that amount of Doppler shift.
Yes. To some degree.
It depends on acceleration though. If acceleration and deceleration take long enough, it could take an entire generation to get up to a fast enough speed that relativistic effects make any difference, and another generation to slow down enough to interact with anything you might see.
Plus if you're traveling at near light speed, running into any matter at all would be pretty devastating for whatever craft you're in.
Edit: someone further down claimed that the math says that accelerating at 1G would get you to 0.1c in a month, so that's actually not that bad all in all. I still maintain that hitting any matter at those speeds might be unpleasant.
> that accelerating at 1G would get you to 0.1c in a month
Minor problem is that we don’t have any technology that’s close to capable of that. And at 0.1c relativistic effects are barely noticeable.
But unless you have a way of slowing down again you'll never see anything of your destination, just the briefest of flares of light as you sail past. And if you do have a way that involves anything like physics that we recognise, you've brought along a huge rest mass that then got accelerated to near light speed. Probably your civilization needs to be approaching Kardashev Level 2 to pull this off.
One thing I've always wondered is what fraction of c is actually realistically achievable with current technologies? (Maybe with scenarios for manned/unmanned spacecraft.)
Like are we at 0.1% or 0.01% or more orders of magnitude off?
According to the first Google hit, https://scitechdaily.com/nasas-parker-solar-probe-the-fastes... , the fastest we've made so far went 430k mph (falling towards the sun), or about 0.064% of c. Good guess.
If you enjoy such questions, I highly recommend https://www.amazon.com/Indistinguishable-Magic-Robert-L-Forw....
The best speed for interstellar travel with technologies that current theory says should be within our reach can be achieved with a vehicle with a light sail pushed by a giant laser, that is powered by solar power. There is even a way to brake it when it reaches the target star. I forget what the predicted velocity was though.
This technology is basically the same as one that the Moties developed in the story, The Mote in God's Eye.
Slow down by pulling on the fishing line tied to the back of it, carefully.
It slows down by releasing a large light sail in front of it, designed to reflect light back to a much smaller light sail behind it. The laser then pushes the large sail away, and as the sail goes it pushes the smaller sail (and ship) back. This leaves the ship at moderate speed relative to the new star, and a large sail traveling very, very quickly beyond it.
We do not yet have this technology. But we can show that it is plausible.
We have a number! Around 0.1c maximum and unsurprisingly it involves using nuclear bombs to push yourself.
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
> "A photon instantly travels to the end of time"
Please explain this. TIA
First set gamma as being 1/sqrt(1-v^2/c^2), with "c" being the speed of light. The factor for time dilation and distance contraction in special relativity is gamma and 1/gamma respectively.
That means that when you get to speeds equal to c, your time runs infinitely slower and the distances are infinitely shorter. So if your clock is infinitely slower, so every travel at "c" speeds means that no time passes for you. And if your distances are infinitely shorter, all travels at "c" speeds cover any distance as immediate. So you could reach every point of the universe as if it was immediately closer and in no time at all.
So in the frame of reference of the photon, the moment it is created it has already reached its destination, be it wherever it is on the universe.
Of course we can never reach "c" as beings with mass, but we can get closer to that. So for example if you get to 99.99999999999999% of the speed of light, you could travel a distance of 54,794,520 ly and only one year would pass to you, while 54,794,520 years would pass on earth.
Follow up question from someone who's mostly forgotten his university physics.
Do photons actually exist, in the traditional sense of physical matter.
Or are they just a convenient short hand to describe the transfer of energy via waves in the fabric or space time, if they dont experience the universe when passing through it but only when interacting with matter and matters "dents" in space-time.
As a non-physicist, my understanding is that they actually exist, but can't be thought of as flying around like ping pong balls. I think it's one of those things that comes down to interpretation though, where the math is very clear but how you think of what it "means" lies beyond science.
Went on a slight rabbit hole reading after posting this and seems like we're all just excitations in a stack of quantum fields :-D
thanks, great explanation
That doesn’t make sense - if you were traveling at the speed of light, it would take you 5000 years to travel 5000ly - longer if you were just ‘very close’ to C. Time wouldn’t advance slowly for you, it wouldn’t advance perceptively different at all - you’d still live every second of those 5000 years.
I dont think you are right. Light for example doesnt perceive time at all. From the photons point of view it never aged even a microsecond while it traveled lightyears. Time is relative too so from our POV 1 year passed when a photon traveled 1 ly, but for the photon no time passed.
Read up on time dilation and special relativity. Time absolutely does pass slower for you as you accelerate.
You two are talking about different meanings of "time".
Traveling 5,000 LY at 0.5 c will cause you the spaceship pilot to age 20,000 years. It's non-relativistic, inside that inertial frame. Clock second hands still sweep slow but noticeable circles.
Meanwhile, everyone outside of the spaceship is happening FAST, by your observations. You'll see stars turn red and go supernova.
The journey will take 10,000 years for an external stationary observer and about 8695 years for the pilot.
It’s not the destination, it’s the journey :)
10,000 years of empty space to get to the next solar system. Exciting.
Not with light speed travel. At even 1% the speed of light, the travel time diminishes significantly:
- Titan, Io and Ganymede are only 2.5 days away - Pluto is about 23 days
Edit: Even at such speeds, we still can’t visit a nearby star system in a reasonable time-frame. Oh well.
As time passes, the universe is expanding infinitely in every direction from every point.
Even if we could travel at 1 percent the speed of light, the "destination" would be inflating away from us at much greater relatavistic speed.
To your point, this is less an issue with solar or extra solar objects.
Doesn't this depend on the initial distance to the destination? I'm thinking you have to be going ~140M light-years for cosmic expansion to exceed 1%c, and Proxima Centauri is only ~4 light-years away
Traveling at .1c within the solar system wouldn’t really be feasible due to the need to accelerate and decelerate. Not for meatbag ships anyway.
There's nothing about 0.1c or even 0.999c travel that's detrimental to meatbags. They would both feel exactly the same to the traveler. If your (for now) imaginary rocket could accelerate at a constant, gentle 1G, you could reach 0.1c in about a month (traveler's time), and you could reach 0.999c in about 44 months. Building and fueling such a rocket is the hard part.
It depends on how you define the bounds of the Solar System, but eg. a flight from Pluto at its most distant to the same distance on the opposite side of the sun that hits .1C at peak needs ~5G for the entire duration. And it seems quite wasteful to bother getting up to speed before immediately reversing the acceleration.
If you're travelling between points in the Oort Cloud, 1G should be more than sufficient to hit .1c on the trip.
My point was that the GP talked about flight times assuming instantaneous acceleration and deceleration. Also, 1G of acceleration sustained over a month is more or less impossible for meatbag-sized spacecraft, especially if you need to also accelerate all the fuel you’ll need to decelerate. The rocket equation is simply way too brutal. Something like nuclear pulse propulsion might come close. Or antimatter propulsion if we’ll ever be able to create and store entire moles worth of antimatter.
Plenty of time for reflection on one’s choices in life that put them in that situation.
Especially generation 143 of 330, they can definitely spend their whole life on that reflection.
Speaking of which, Peter Watts' Sunflower Series has a great and short enough hard-ish scifi story about just such a ship.
We can instead happily drive our solar system in a different direction by nudging the sun.
At this point in humanity's history, I think that's more feasible than high speed traveling.
Assuming our models of the universe are correct, and faster than light travel is impossible. There are very strong reasons to believe this, but perhaps we can cheat by stretching and compressing space around us.
It makes me wonder what kind of "life" could perform interstellar travel? I used to imagine a spaceship being alive, with people inside being analogous to "cells" in a multicellular organism.
Perhaps this is really how AI achieves consciousness?
https://en.m.wikipedia.org/wiki/Generation_ship
To make a generation ship work you have to build a self-contained ecology that is stable and self-repairing, inside mechanical and software systems that are fault tolerant and either extremely redundant or self-repairing, run by a political and social system that is also fault-tolerant and self-repairing.
We know how to do exactly zero of those things.
More to the point the ship needs to be absolutely self sufficient, it can't even use solar power and has no access to outside mass whatsoever. But if you have a ship like this you could build an orbital habitat using the same technology, and it would be much much easier to build since it doesn't have to accelerate, can use solar power, and has access to the rest of the resources of a solar system.
If you have all of this why would you go to the enormous extra effort to move the habitat to a different solar system? Even if your civilization is so old that the star is a dim brown dwarf that's still plenty of energy for day to day life.
There's a CRPG I've been meaning to play where this is basically the plot; there was a generation ship, it was heading towards some planet or another, but the social and political structure on the ship broke down at some point and now there's no one actually in charge, the ship is getting run down, and they probably blew past their destination a hundred years ago if they were even still on course at all.
I remember someone pointing out that a generation ship could be problematic because you have one generation who decides to launch this expedition but will never see the end, multiple generations who didn't choose this life and won't get to see the benefits, and then one generation who actually gets to the planet but might not even want to be there. Without some kind of cryogenic sleep or relativistic speeds the whole thing might fall apart just because most of the people involved "didn't sign up for this" but they have to toil away anyway for someone else to benefit from it.
What of the "just so" attitude of a child growing up? Everything is taken at face value, there is no comparison, only stories (unless you have a catalogue of 30EB of 8K earth footage or something to that effect for them to fawn over). They don't have the reference frame for other situations for a while, perhaps long enough to not be able to see things differently?
This makes me think of multi-generational migrations north out of Africa. There's only so much that can be passed orally losslessly. Eventually the group in north siberia after 20K years doesn't see living any other way.
> I remember someone pointing out that a generation ship could be problematic because you have one generation who decides to launch this expedition but will never see the end, multiple generations who didn't choose this life and won't get to see the benefits, and then one generation who actually gets to the planet but might not even want to be there.
That isn't really different from the way things are now. We are, in fact, traveling through the galaxy for many generations and none of us signed up for it. We just happen to be on a largeish ship and have no destination.
> run by a political and social system that is also fault-tolerant and self-repairing
That's the point of the AI; it would generally replace that.
Well, to be frank, we currently have such a ship, but we're doing quite a lot to disrupt its capability of sustaining human life.
Of course, even if we stopped doing that, we'd need to figure out how to visit another place if our ship is passing close by. That also seems to pose a problem: both Voyagers are barely out of the exhaust fumes of our ship's motor, and getting so far took ~40 years.
> It makes me wonder what kind of "life" could perform interstellar travel?
That’s essentially the premise of Project Hail Mary. Good book.
It's a wonderfully entertaining book and for that reason I loved it, but Andy Weir really, really glosses over and hand-waves away all kinds of other difficulties for so quickly and easily building a ship that can travel at nearly the speed of light.
He basically just has it work because the fuel difficulties are solved and bam, the main character can zip around nearby start systems at close to perfect C on a ship built with little more than our current 21st century technology. Fun, but not even in the most basic way an attempt at presenting any science seriously.
What makes it more amusing is that for many other parts of the main drama, he puts a lot of effort into making the descriptions and scenarios seem as realistic and science-rich as you could like. I suspect a lot of entertaining word salad there too though.
Not if you are an immortal AI or uploaded human.
Meh, most of it is just more of the same thing. I'd rather play with a paper plane than float in space.
Maybe light’s insanely fast and space is just huge. It’s all relative ;)
I would say they're two sides of the same coin. The time it takes for light to travel the universe (which makes communication even with nearby stars essentially impossible) is what makes the universe huge.
Luckily FTL communication isn't actually impossible and special relativity only applies to energy and mass.
I can't tell if you're joking or if you know something nobody else does.
As far as I know, anything going faster than the speed of causality violates causality. So what are you talking about?
> violates causality
But we don’t know that casualty is a law of physics, do we?
Only inasmuch as we don't know that gravity and the Strong Nuclear Force aren't.
Don't conflate causality and special relativity.
SR breaks down at both ends of the spectrum, at the event horizon of black holes and in Bose Einstein condensates. That proves that it is an emergent property of observations, statistical behavior of decoherent systems, and not a universal law.
FTL communication is actually impossible, what are you talking about?
> I think we'll have a holodeck before we reach another star. And maybe that'll be enough.
I agree, but not because of the relative difficulty of the technology, but because we spend way more on entertainment than space exploration.
Depends on who you mean by we. The universe is weird and it's entirely possible for you or I to travel essentially arbitrarily far in a single human lifetime, easily billions of light years. Relativity doesn't simply work as a speed limit; instead when things approach velocities anywhere near the speed of light, the universe starts contorting itself in really weird ways to maintain the perceived consistency of the speed of light.
From the perspective of somebody in a ship moving at relativistic rates, distances would begin to physically contract, and time itself would begin to speed up relative to an at rest observer. Here [1] is a calculator to see what this all mathematically works out to. For instance, you could travel to Andromeda, some 2 million light years away, in about 28 years in a ship that was capable of sustaining acceleration at 1g for 28 years. Of course for everybody back home 2 million years would pass. So if we ever achieve ships capable of this sort of acceleration, life is going to get really weird and non-linear, so far as time is concerned.
And this isn't some just some weird fringe theoretical/mathematical thing. For instance GPS satellites have to compensate for time dilation because relativistic effects, though small in this case, would otherwise have a substantial effect. Another example is at things like the large hadron collider. As a convenient effect of relativistic effects, emergent unstable particles exist far longer than they 'normally' would before decaying due to the fact they're moving at relativistic rates.
In other words, this is all very real. The only questionable issue is whether we can discover some sort of an energy source capable of accelerating a ship at 1g for tens of years, and develop sufficient shielding for such a vessel. That's still very much in the domain of sci-fi, but simultaneously seems like something that one wouldn't be entirely surprised to see was discovered just a century from now. This was the most tantalizing possibility behind the EMDrive stuff. [2] Well that or infinite energy, but it seems that universe won't be broken quite so easily just yet.
[1] - http://www.convertalot.com/relativistic_star_ship_calculator...
[2] - https://en.wikipedia.org/wiki/EmDrive
True but doesn’t matter how slow light is. The closest to c your speed is, the shortest the time you experience on board of the space ship. At light speed, space and time cease to exist. You reach destination instantly.
So the goal is to create engines that can take us close to light speed. Then the issue is braking (spacetime expands as you slow down…)
Me scrolling is faster than the speed of light!
Nice.
Dude, chill.
We’ve got to preserve causality. :P
> Lightly is incredibly slow
Its relative! Sitting on a couch and watching the pixel move from the sun to the earth for 8 minutes feels incredibly slow but if you are actually traveling in a light speed aircraft then it won’t feel that slow.
If you were actually traveling at the speed of light it wouldn't feel like anything at all! Photons don't 'experience' time—any length trip would be instantaneous from the traveler's point of view.
Quite the opposite, much like when skydiving, going really fast without any close reference point makes everything stand still. And in space, there wouldn’t even be (very loud) atmospheric drag to physically remind you about what speed you’re actually going.
I believe the OP was referring to relativity - the closer to the speed of light you get the slower time appears to tick. So if you could travel at light speed you'd arrive at your destination immediately from your reference frame, but much slower from another person's.
Then what’s up with all of those sci-fi chows where using FTL still takes some amount of time to arrive?
1) it's better for the plot and drama to have travel time. FTL in fiction is always analagous to some known terrestrial form of travel (usually ships and boats) and the limitations and parameters of FTL in a fictional universe shape the narrative in necessary ways.
2) it's assumed within the framework of the fictional universe that time dilation isn't taking place because the actual travel is occurring within an external frame of reference like "hyperspace" or a "warp field."
Screenwriters don’t understand much science.
If you travel at relativistic speeds, your trip will appear far shorter to you than to those that stayed on Earth.
With a ship able to accelerate at 1G continuously, you can be at the edge of the observable universe in <50 subjective years [1].
[1] https://www.reddit.com/r/dataisbeautiful/comments/s4tbry/oc_...
Naive question: is accelerating at 1G continuously within the range of what we consider possible?
Amazingly, yes, in a few ways (the mechanics are possible). But no in as many ways. (Fuel, sustainability, tracking)
The greater barrier is that the nature of the expansion of the universe prevents any real interstellar travel that has a "destination" in mind. Of course we might have some "FTL" or "near light speed" travel in futre, but if the universe is expanding infintely from every point in space at light speed, how could we ever "catch up" to objects we see even now?
If your travel involves the Rocket Equation the answer is no. If you are limited by the speed of light and the lifetime of human civilization then the expansion of the universe is not an issue. Traveling between nearby solar systems is very close to impossible, traveling between galaxies is outright impossible.
The lifetime of human civilization problem is an odd one, because due to relativity, one-way trips are not an unsurpassable hurdle ( 2-3 generations on a 1 G spacecraft to get pretty much anywhere). But you can't come back, because it's basically guaranteed there'll be nothing left for you to come back to. Because while it might take "only" two hundred years from the passengers perspective to reach the edge of the (current) observable universe and come back, they'll be arriving 90 billion years in the future.
The objects you can (eventually) reach are proportional to your speed. For example at half light speed you could catch up to objects nearly halfway to the Hubble Horizon, about 7 billion light years away.
This is not true. Expansion does not affect gravitationally bound structures. Our galaxy, and even the other galaxies in our local cluster, will stay in reach.
Source: https://www.reddit.com/r/askscience/comments/sr7fuo/is_there...
It's a simple question of weight ratios.
Not naive at all. With chemical rockets we can only sustain 1G for a few minutes, so it won't do at all for interstellar flights.
There is a known way to achieve 100% fuel efficiency: antimatter. By storing equal parts matter and antimatter, you can fuse them to propel your spacecraft. It's unknown wether or not this kind of engine can actually be made.
Alternatively, and even more far-fetched, you could onboard a small singularity. Dumping anything into it will result in it being turned to pure energy at 100% efficiency, through Hawking's radiations. The smallest the singularity, the fastest it radiates, meaning you can sort of control the output. You can create singularities with very large particle colliders.
With 100% fuel efficiency you can probably sustain 1G for long enough to reach the nearest stars. You would need a very large spacecraft (on the order of kilometers) for a comparatively very small payload. And it would arrive completely empty at its destination, meaning no turning back. I think I saw someone do the math, but can't find it anymore.
Anyway, there are other difficulties. Travelling at .99c means tiny space dust now becomes very dangerous. So does radiations, all made extremely energetic by the Doppler effect.
On the plus side, continous 1G means you have artifical gravity for the whole trip.
I really thought hitting "light speed" would just zoom it all in a minute, but nope... So much for my physics preconceptions.
> would just zoom it all in a minute,
The Earth is about 8 light-minutes away from the Sun :)
I am not liking this fact.
The sun could have exploded seven and a half minutes ago and we’d have no idea! Enjoy the next 30 seconds of your life.
Well, if you were traveling at light speed you could move anywhere in the universe instantly. If you are an observer on earth, watching an object move away from you at the speed of light, then it will take a very long time to traverse the tiniest regions of the universe.
Er, "instant" here is "relativistic instant."
even in a vaccum, light speed travel from the travelers POV still takes time, and said traveler would perceive time passing exactly as occurring in that local space. But yes you're totally correct, the observer on earth would in this time see only the briefest part of my journey's trail due to light from my journey taking "exponentially" longer to travel back to the observer.
what's your definition of a holodeck? i only know the one from star wars and thats kind of a toy
Alternate view:
be thankful things are far apart
a gamma-ray burst from a collapsing star closer than 200 light years away would destroy ALL life on earth
We’re barely even using our first solar system, it’s way too early to be worried about reaching other stars.
Exactly, there is free fuel and aluminium just floating by, and we are unable to use them to upgrade our ships or refuel them.
Until we make full use of robotics and 3D printing, there is no point of heading far. And we have all the tools.
Distant stars will not be settled by a fast small ship travelling from earth. They will be settled by a city sized monolith produced by harvesting and smelting an entire small moon
> Distant stars will not be settled by a fast small ship travelling from earth. They will be settled by a city sized monolith produced by harvesting and smelting an entire small moon
I don’t even think you’d need a whole moon unless it was a tiny one. Nonetheless, by the time we send a ship to another star, building these kinds of large self-contained habitats will be old hat.
Need that warp drive
Stephen Baxter wrote a story named The Gravity Mine about the descendants of humanity living after all stars have died. They get energy from black holes but even they are starting to noticeably shrink. Their perception of time is billions of times slower than humans and the upshot of this is that the speed of light would actually seem pretty fast.
https://www.infinityplus.co.uk/stories/gravitymine.htm
All of fiction and discourse fails to consider that the Solar System is actually a huge place and just the period of settling and industrialising it will take hundreds of years.
Everyone things that a game breaker technology is better engines, or fusion, or FTL, but they are wrong, the game breaker technology has already happened: 3D printing.
If we can manufacture things with minimal infrastructure using local resources, we can that is all we need.
And all of it reachable with simple nuclear power and technology we have today.
you would need a ship that is also a city. a traveling space station. or probes. if humanity decided to send a small probe to the nearest foreign star, i wonder how many km/h current infrastructure could accomplish
I love how simple the HTML/CSS is. Absolute positioning with really large left: values.
Caused Brave in iOS to crash. I have a newer iPad mini with 12GB ram too. But luckily It didn't crash until I tried to close the tab.
This seems like a browser issue more than anything else. Yes it's "weird" to have millions of pixels horizontally on a page that is only a few thousand pixels tall, but it seems like an absolutely reasonable edge case that the browser should support.
I feel there's a joke here about "edge" cases from scrolling ridiculously long horizontal distances, but I'm not smart enough to make it.
And then it’s asking for Internet Explorer joke then, as an explorer something, not I’m not able to come up with it either.
“Why not save space by storing dimensions as uint16 internally?”
For the record, this HN page is already about halfway to overflowing uint16. The most popular HN page in the last day would overflow uint16.
Huge values could rise problems on IE (if someone keep using it and supporting it)
We have come full circle. I'd imagine that px uses a surprising amount of abstraction.
Anyone that has tried to absolutely position shapes on an Excel spreadsheet via code would probably agree.
Who the hell decided to make EMU’s??
Shameless plug: Accurate solar system in 192 Bytes:
https://www.dwitter.net/d/26521
The red bit is the sun. 1000 kilometers per pixel, and 1000 seconds per second.
They all fit onto the screen by looking through the orbital plane, as if through a telescope from a distant world, i.e effectively an orthographic projection. The orbits are accurate in terms of mean orbital distance (in reality there is slight perturbance) and sidereal periods.
Incredible - how does this work?
You mean technically? I should have posted the beta dwitter link which has the "compress" toggle, because most dweets are unicode packed. https://beta.dwitter.net/d/26521
Here's the js anyway:
This one is actually relatively simple to explain, it loops over the 10 planets (i), and draws a circle for each, with the position and size all being defined in the x.arc method. Planets are differentiated by the arrays of values selected by [i]. The X position is calculated as the orbital distance multiplied by the sine of time / orbital period... d x sin(t/p). But d and p are substituted for the value for each planet using the arrays [1,2,3][i].Surprisingly the precision used in those encoded values is enough at 1000km per pixel (I checked).
I presume including Pluto's parameters in the array is both a rebellious statement and a brag. ("Yes, my JS snippet could have been even shorter if you asked the IAU.")
Actually I couldn't fit Pluto, I sacrificed everything I could, but to fit it would require sacrificing the precision of Mars, Earth and Mercury (dropping the decimal), but I wanted to maintain enough precision to be able to tell them apart by size (which you just about can at full screen due to antialiasing)... Otherwise I definitely would have included it for that very sentiment ;)
The reason there are 10 radi is for 8 planets + sun + drawing the black backdrop (2e3): [24,25,58,69,3.4,6.4,6,2.4,696,2e3]
I remember back in elementary school, way before we had such things on computer, we had a vinyl roll for the age of the planet. You'd roll it out in the hallway, starting with present day and watch as the different time periods came into view. You were just a few feet at the origin of man, at the end of the hallway by the time you got to the beginning of Cambrian era, and out the door and across the huge athletic field before you got to the formation of the planet.
Still an extraordinary experience after all these years and possibly the best use of horizontal scrolling I’ve seen. Lots of previous discussions and posts on HN: https://hn.algolia.com/?q=if+moon+only+1+pixel
It's very very good! I thought this one hit hard though, I assume inspired by the moon = 1-pixel viz.
https://hmijail.github.io/1-pixel-wealth/
This is great, but it needs an update: wealth inequality is even higher today than it was when that site was created.
E.g. it gives Jeff Bezos's net worth as $139 billion, but today it's $228 billion.
that's a great share, I feel like it would also benefit from setting the "speed of light", as something like median average yearly income.
On the same note: https://xkcd.com/980/ (from 2011 when Bezos "only" had $18b)
Related. Others?
If the moon were only 1 pixel - https://news.ycombinator.com/item?id=39686916 - March 2024 (1 comment)
If the Moon Were Only 1 Pixel (2014) - https://news.ycombinator.com/item?id=32936581 - Sept 2022 (108 comments)
If the Moon Were Only 1 Pixel (2014) - https://news.ycombinator.com/item?id=27573172 - June 2021 (69 comments)
If the Moon Were Only 1 Pixel (2014) - https://news.ycombinator.com/item?id=21735528 - Dec 2019 (82 comments)
If the Moon Were Only 1 Pixel – A tediously accurate map of the solar system - https://news.ycombinator.com/item?id=13790954 - March 2017 (81 comments)
If the Moon Were Only 1 Pixel – A tediously accurate map of the solar system - https://news.ycombinator.com/item?id=13217129 - Dec 2016 (11 comments)
If the Moon Was Only 1 Pixel - https://news.ycombinator.com/item?id=12038584 - July 2016 (4 comments)
A Ridiculously large accurate scale model of the Solar System - https://news.ycombinator.com/item?id=10330303 - Oct 2015 (1 comment)
If the moon were only 1 pixel: a scale model of the solar system - https://news.ycombinator.com/item?id=7551423 - April 2014 (17 comments)
If The Moon Was Only 1 Pixel - https://news.ycombinator.com/item?id=7341690 - March 2014 (178 comments)
When I was dabbling with POV-Ray many moons ago, I drew the planets of our solar system to scale with it. You can see it here: https://github.com/susam/pov25#planets
A friend once asked if I couldn't show the planets in orbit rather than lying flat on a plane. I could, of course, but this is ray tracing. What do planets actually look like to human eyes from Earth? Just tiny dots.
If I were to show them in their proper orbits at scale using perspective projection, I'd only be able to render one planet large enough to be visually interesting. The rest would appear as small dots. I didn't want to use an orthographic projection, as it wouldn't reflect how we actually see the universe.
Those were, of course, limitations of a still image. An interactive page like the one in the original post does a fantastic job of conveying the vast scale of our solar system, both in terms of the sizes of the planets and the immense distances between them.
Would you have to use double precision to ray trace the planets in their proper orbits at scale using either perspective or orthographic projection? With the ratio of Neptune’s distance from the sun to its radius being almost 2M, I’m guessing fp32 rounding would turn Neptune into a couple of squares if the sun was at the origin. What other challenges would there be? Maybe I’ll try it today just for fun.
I tried it, including Pluto, and it works fine. Shading is quantized at Pluto but the spheres are all round.
The light speed toggle really hammers home the emptiness. Like, I know that the Earth is ~8 light minutes out, but sitting and waiting 8 minutes for a few pixels to appear when scrolling away from the sun…
and even this is not making it super tangible, because the speed of light to monkey brains is basically infinite.
There are many physical scale models of the solar system around the world, many walkable, some bikeable: https://en.wikipedia.org/wiki/Solar_System_model
I've seen several, Planet Trek in Wisconsin is a good bikeable one with high quality signage. The sun is downtown, the moon is the size of a peach pit, Pluto is ~20 miles away.
And for the lazy, there's the 1:1 scale model under your feet.
Given the great distances and how small the planets seem at that scale, I'm surprised that we can see any of the planets with the naked eye. Thinking about Jupiter, it's 140K km in diameter and about 629M km from Earth. That's a ratio of 1:4500. So imagine a U.S. dime that is 1.8cm in diameter placed 1.8 x 4500 = 8100 cm away. Would you be able to see a dime that it 81m or 266ft away at nighttime, assuming it slightly illuminated? We can see Jupiter, so I guess we should be able to see the illuminated dime too.
I've seen countless analogies that explain the size of space, but this was really something else. Especially how frustratingly slow the speed of light felt.
One of my favorite visualizations of the scale of the solar system is from Stephen Hawking's Genius.
https://mass.pbslearningmedia.org/resource/hawking_genius_ep...
It's a hands-on, practical example of how far things are away that we can easily visualize. I highly recommend the rest of the series as well. It's one of the best science shows ever produced. It shows the practical path of scientific discovery. You can watch is on the PBS app, which requires a $60 a year pass. Highly worth it. (I have no affiliation with PBS)
Not the same but related? Powers of 10 by Eames
https://www.youtube.com/watch?v=0fKBhvDjuy0
Interestingly, that Hawking visualization makes all the same affordances mentioned in the 1 pixel visualization. They show the earth and moon to scale, then the video shows an aerial view with all the planets much too large. Jupiter is 2x the size of the sun. Saturn and its rings 2x that.
I've always used this aprox dimensions:
Lets divide it all by 1M. So if the sun is 1.4m in diameter, it would be located 150m from earth which would be 13mm in diameter and the moon would be 3.5mm located 0.3m from earthSimply put, imagine a yellow beach ball the size of a washing machine located a block and a half away from your house, a blue marble being the earth on one side of your keyboard and a peanut being the moon on the other side
Now, using the basketball 24cm (earth) and tennis ball 6.5cm (moon) comparison, they would be separated by 7m in your living room and the sun would be 13m tall (a cherry tree) located at 3km from your house
Scrolling with mouse scroll wheel a few hundred thousand kilometers at a time is so much work that I gave up :-(
I'm thankful that the view-source:https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.... allows one to see the annotations since clicking on the planet jumps scrolls past them. My gratitude for not baking such things into 8MB of JS
Also thanks to the view-source I learned that it offers different units, including busses, Great Wall of China, etc
Repetitive strain injury any% speedrun
Click on the planet symbols at the top to fast track.
Its quite cool on the phone
One thing to notice is how small Mercury is, only 1 pixel like the moons that show up. Here's a good photo size comparison. Mercury is smaller that two of the solar system's moon!
https://en.wikipedia.org/wiki/Planetary-mass_object#/media/F...
EDIT: And Pluto is smaller than all the moons almost anyone has heard of.
How does all that space out there make you feel about the 30 years of paying off your mortgage for all that 0.25 acres of land you own? ;) J/K
Thank you for including Pluto!
Previous discussions (there are many!)
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
Unrelated, but the Elon dream of getting a human colony on Mars seems beyond imagination. Ignoring safety of such a long travel, the radiation issue of Mar's surface, and the massive infrastructure to have a self-sustainable biosphere (also somehow protected from radiation) to recycle enough oxygen, we still have to deal with the immense number of failures that could happen with no way to send help.
Like, building a fully self-sustainable underwater city or moon base would be far more in reach. It feels that SpaceX should start with prototyping these safer alternatively before overreaching to something 100x more challenging and dangerous.
> Like, building a fully self-sustainable underwater city or moon base would be far more in reach. It feels that SpaceX should start with prototyping these safer alternatively before overreaching to something 100x more challenging and dangerous.
I've been beating this drum for years. Elon is 100% focused on building the rocket that can get to Mars and neglecting absolutely everything else about the project. Where is the self contained biosphere pilot program on Earth that tests the Mars habitat? To be anywhere close to Elon's timetable it needs to be running today, and honestly it should have been running years ago. Given the extreme reliability requirements it needs long term testing to build any confidence at all in the numerous technologies involved. The closest model we have is the ISS, and it's mostly shown that we aren't ready for a Mars habitat. The ISS requires way too much maintenance and ground support.
The problem with Mars is that if something goes wrong you can't just "fly back on the rocket". The launch windows are 2 years apart. You either fix it in place or you die.
At least theoretically it should be doable. But I think it will be similar to the moon landings. My prediction: People are going to lose interest in the project very quickly. It will be prohibitively expensive to maintain and there is simply nothing to do. You couldn’t even really have a remote programming job there. A light round trip takes between 6 and 44 minutes, completely unsustainable.
If you're really interested in a deep dive on this subject then I really recommend "A City On Mars" by Zach and Kelly Weinersmith (of SMBC). It goes very deep into things like - can you have babies successfully in space?
It's very clearly not "beyond imagination". It doesn't require any fundamentally new technology.
It may well be beyond our ability to practically apply those technologies at the required scales and reliability levels, but that's hardly unimaginable.
Preventing cancerous damage from radiation is absolutely beyond our tech.
Unless you consider launching a lead-lined spaceship "within our tech."
The marsonauts won't die before reaching Mars, but their lifespans will be significantly shortened.
This makes the Theia hypothesis all the more extraordinary https://en.wikipedia.org/wiki/Theia_(hypothetical_planet)
I believe the scientific record is drawing a consensus on this as the moon's origin but the wild sparseness of space just makes this sound really unusual.
We’re never going to leave this planet/solar system if we don’t discover FTL (Faster Than Light) travel. Pretty scary if you think about how ridiculously empty is space.
We can leave it pretty easily. :p Only took Voyager 1 about 40 years.
If ~1.0C is the fastest man can travel, that's still pretty good. Alpha Centauri is in reach (less than five light-years).
Alpha Centauri is a triple star system with no habitable planets. Why in the hell would you go there? Sending people to another solar system is so resource intensive that assuming you can convert the entirety of Jupiter into some kind of orders of magnitude more efficient exotic rocket fuel you might have enough resources for a small handful of expeditions, so you really need to make them count.
Maybe it would make sense if you could convert the mass of Proxima Centauri into rocket fuel to fund more expeditions? That seems like a fairly long term plan though.
I mean, why did we go to Mars without any intention of colonizing it? The Moon?
Exploration is what humans do. If Alpha Centauri is only 5 years away, you can bet we're sending people there no matter what. Permanent colonization only becomes a priority in an existential event, and if we eventually achieve ~1.0C travel then that implies our tech is at a level we'd be colonizing Mars and a few moons long before we think about leaving the solar system.
Even getting to 0.9C is going to be very very hard for humanity.
I've always thought that people pushing for colonization or even commercial exploitation of space simply don't have a good sense of how far things are and how empty the space between us and those things are.
That has always been the case, there is loads of empty distance between big population centers even today there are big cities many hours by flight from anywhere else of interest.
In the age of sail, people were perfectly willing to spend months in transit .
Transit times for most objects of commercial interest (i.e. upto moons of Saturns) is only in years if you use a low energy/Delta-v Hohmann transfer orbits and/or gravity assists as is common today for probes.
Direct transfer would be expected for human transits , those can be fairly quick . Transfers to mars within the next 1-2 decades is doable in 6months or less.
There are no fundamental breakthroughs needed to go any orbits we would be interested in 1 year or less by end of this century.
On the other hand I do agree going interstellar is a whole different scale of empty and without near light speed (even with ) is probably out of reach .
I’ve been thinking about how to teach the size and proportions of the solar system to my kids, I’ve bought a couple of packs of blank RFID cards on which I intend to paint the planets over a starred background. And then walk with my kids the meters necessary to cover the distances before displaying them. What I don’t know is if there is a clever way to use the RFID tech, this website kinda offers an idea.
Or you could come to Sweden :)
https://en.m.wikipedia.org/wiki/Sweden_Solar_System
space engine is neat
This is a great website—it reminds me of To Scale: The Solar System [1], a mini-documentary where people attempt to build a true-to-scale model of the Solar System. It makes me feel like a tiny speck of dust, floating in the vastness of nowhere...
[1] https://www.youtube.com/watch?v=zR3Igc3Rhfg
I just love that this is still online after all these years.
Look I'm no astronomer, but I'm pretty sure celestial bodies all have elliptical orbits, so if you're going to label something as 'tediously accurate' you should give some indication that the distances from the sun are changing over the orbital period.
Didn't have the patience to read the fine article? Understandable I guess, but I thought it was worth the effort. Quoting from it:
> All these distances are just averages, mind you. The distance between planets really depends on where the two planets are in their orbits around the sun.
I've seen models like this before. We live in a universe with many, many orders of magnitude. In both directions. Living creatures to small to see, space too big to comprehend.
Mining asteroids for space resources sounds great, right up until you consider the distances involved. Living on Mars - yes, we really should - but you sure aren't going to support a colony long-term from anywhere but local resources.
We are pumping oil that's located under the seabed. It would have seemed completely insane in the 19th century when all oil was easily accessible. Asteroid mining might be feasible in a few decades. If it really gets going - it could make gold as cheap as aluminium is today.
The way I often visualize the solar system is:
If the sun would be the size of a coin, then earth would be around 2m away from it and so small you could barely see it.
This is super cool. It's crazy to think about asteroids in any depiction of the solar system look so packed that I thought a spaceship would never be able to pass through unscathed, but here it's all black because they are basically irrelevant lol
Also crazy how far Jupiter's gravity can keep a moon??
Reminds me of a 23 mile long model of the solar system in Madison https://www.astro.wisc.edu/outreach/planet-trek/
Importantly, the planets aren't actually lined up nicely like on the site. Right now, Mars is ~5 times further then shown.
That's why so many people were taking pictures of Mars back in January, when it was actually possible to take see detail. Right now it just looks like a red orb.
> tediously accurate
Could the planets and moons ever all be aligned like this when viewed from an infinite distance?
This is truly marvelous! Not only is the horizontal scroll really extra awesome for making me feel the distances...but as others stated, the moment you toggle on the light speed....wow, it really is quite profound! Amazingly done!
How does this website work? I feel like I'm stuck on the first screen maybe? It says 'scroll to explore' but there are no scrollbars. Does it only work with a mouse with a scroll wheel?
Scroll horizontally, to the right.
This was so cool I would add the planets as indicators on the right side and by clicking on them I would move the timeline fast to reach them
somewhat defeats the point I think (but they are at the top if you really want to)
How many times can you go from Beijing to Lisbon ?
I love it, I always love these things. Still, given this is a technical site, one small nitpick is that it would be nice on hover to see how many pixels the current object is.
No need to hover, the drop-down next to the measurement at the bottom has Pixels. Clicking on the Pluto quick-nav shows that it is 1,700,530px
> We're always trying to come up with metaphors for big numbers. Even so, they never seem to work.
Yeah, that Googol often doesn't work.
I love the little facts sprinkled throughout
I've probably thought about this website daily or weekly since it originally came out. Glad to know it still exists.
The universe is a UI nightmare
I like the other one where you can zoom in/out to planck level or to the unobserved universe
You may think this page is big. But that's just peanuts to space.
Love it! Are there stats on how many people scrolled to the end? :)
The planets are just grains of sand in a vast empty space.
sit back and relax for my 1px review
tedious=true, basicallyLame=true, is1px=false
Wot no Oort Cloud?
It's not space that's big and out of reach, it's just us living too fast.
Pedantic me : Pluto isn't a planet.
Lovely
nice!
why have we not shot a probe toward the nearest foreign star?
There was a plan in ~2016 backed by Zuckerberg, Hawking and some entrepreneur but it didn't really get anywhere (in a literal sense). Research for it stopped in 2022 because of a "lack of funding".
https://en.wikipedia.org/wiki/Breakthrough_Starshot
https://interestingengineering.com/innovation/mark-zuckerber...
I'm not sure we'd be capable of receiving any signal it sent back to us, would we?
Douglas Adams said it best:
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.