c is technically the speed of causality. The speed at which perturbations in the fields that make up the universe propagate.
The speed of light is a consequence of this, not the cause. Calling c the "speed of light" is putting the cart before the horse.
Photons (being massless) have 100% of their velocity in the spatial dimensions and no velocity in the time dimension. They move at the maximum speed that any change in the electrostrongweak force can propagate in our universe because they are not free to do anything else.
From a photon's POV a trip across the entire universe happens instantaneously - taking no time whatsoever.
Einstein causality, i.e that no physical effect propagates faster than light. In QFT it it is modeled by the rule that space-like separated measurements commute.
That merely equates the term "causality" to propagating waves. It doesn't introduce any new concept. Ontologically, there are only quantum fields in space-time. The physical laws governing them imply from their mathematics that they cannot contain any propagations faster than c. But attaching the term "causality" to it doesn't really add anything here.
This does not equate causality with propagating waves. I also did not claim it is a new concept. Instead I said physics has a precise and fundamental concept of causality.
How is it fundamental? You can do all the physics without reference to it. It is a consequence of the equations, not a premise.
Edit: It is not actually a complete consequence, because cause and effect imply a directonality that the equations do not have, being time-symmetric. At the same time, this directionality or asymmetry has no derivable consequences for the practical physics, meaning having the asymmetry doesn't add anything. This is one of the conceptual troubles that introducing "causality" here brings.
It is used in theories that discuss particles with imaginary mass, such as tachyons, that travel backwards in time.
Theories that violate causality are considered unphysical, whereas theories in which measuring such time traveling particle, cannot be distinguished from creating a particle that moves forward in time are not.
Physicists put this into the theories as an assumption at a fundamental level, e.g. they put it as an axiom into axiomatic QFT. This is why it is fundamental. Also arrow of time is something else than Einstein causality.
"Photons (being massless) have 100% of their velocity in the spatial dimensions and no velocity in the time dimension"
I kinda see what you're trying to say, but these words aren't a particularly good match for the math in special relativity. To an observer, any photon's velocity 4-vector looks like V = (c,c,0,0). That's a "c" in the spatial direction the photon's moving, and a "c" in the time direction. So, plenty of velocity in the time direction.
What is zero is the _proper time_ along a photon's trajectory through space & time. An observer who's co-moving with the photon (call me if you ever meet one, we can write a paper together) would see a) the photon holding still and b) no time passing.
special relativity is undefined at v = c. so no from a photons point of view the trip doesn’t happen in an instant nor does the length of the universe shrink to zero. there is no definition for a photons point of view. time dilation and length contraction only apply when comparing a moving frame of reference to one that is at rest and photons have no rest frame.
And when you think about c as the speed of causality, it becomes a lot more obvious why FTL travel/communicate is (almost certainty) impossible without breaking causality....
You are going faster than causality, of course it breaks.
The other option is to break relativity, which is what most science fiction media does, often accidentally.
If you think it is implied that c stands for the first letter of the word causality, then reading the article should be enough to convince you otherwise.
Einstein published his seminal works in German, and we'd be more likely to have E=mk².
Huh. I'm admittedly no astrophysicist, but I don't recall encountering this "photons have no velocity in the time dimension" before.
Maybe I'm one of today's lucky 10,000[1].
It's not true. It's a mashup of a few ideas that don't belong together.
1. an object at rest has a world line which points (has tangent vectors) in the time dimension
2. light has proper time (dtau) = 0, so clocks moving at the speed of light dont tick
3. the magnitude^2 of an objects 4-velocity is c^2 (objects move through spacetime at c)
4. light has no 4-velocity (because dtau=0, you cant divide by zero)
You can't say (3) means objects have 4-velocity c in spacetime and light has 3-velocity c in space and so that means the time component of 4-velocity for light is zero.
But, it is sort of common to observe the somewhat trippy fact that, unlike matter, photons don’t experience time passing, right? (Although, I will be honest, I could not ever really grok relativity like a physicist. However, I can enjoy the Lorentz factor going to infinity as v goes to c).
From my understanding, it's more correct to say that time is undefined for massless objects.
Through special relativity, our understanding of mass, gravity, and spacetime are linked. If something has no mass, then special relativity can't describe how gravity affects it's spacetime reference.
Remember, however, that this explanation is based on the mathematics that explain the observations we've made or theorized. Just as the map is not the territory, the math is not the universe.
It is, in my opinion, not extremely obvious from the usual descriptions of relativity, but basically when you move faster and faster, you trade your velocity through time for velocity through space. Rather then a funny result, that is the theory.
If you're at rest, you have maximum time velocity (1 you-second per frame-second). If you're at the speed of light, it's zero you-seconds per frame-second.
This is described by the Minkowski space, which is a metric that puts two events the same distance apart in spacetime regardless of reference frame.
Greg Egan's series "Orthogonal" looks into what the universe would look like if time didn't have the opposite sign (so that time is another dimension just like x, y, z). The effects of that one sign change are very wierd.
Thanks for the answer. I had forgotten about the No-communication theorem.
This led me into another rabbit hole :-) of why c is 299,792,458 m/s and for example not 499,792,458 m/s or some other value, and the fundamental constants that bring this value. [1]
Is there a current theory that tries to justify those constants that bring the current value of c ? Are those values the ones that must be, for the current Universe to be feasible?
Veritasium has a few recent videos on Action. In one of them I believe he shows speed of light expressed as one unit of action, which implies that it’s the highest “resolution” any propagation can resolve at based on the fundamentally smallest path integral anything can traverse, or something.
I'm not sure if there is a good theory on why it ends up being this speed, but if any of the constants were even slightly different we wouldn't be in this universe to talk about it.
The speed of light is 1c and is a fundamental constant.
Humans choose to express it in metres and seconds.
A meter is huge if you compare it to the Planck length. Humans are pretty big creatures compared to fundamental particles, so we have a big basic unit of length. But seconds are gargantuan, because humans are absolutely glacial if you compare them to the time it takes light to travel a Planck length.
It's like a continental plate asking why humans zip around so fast.
> The speed of light is 1c and is a fundamental constant.
Yes, but why is the value that it is and not higher or lower? From my (basic) research it seems, it could be plus or minus 20% a different value, and the current Universe would still be feasible.
No, the point is that if it was 20% bigger we would not be here to ask those questions :-) Stars fusion or weak atomic interactions would not work. Maybe Hari Seldon decided....
That touches on a long-running very complicated debate around quantum mechanics, hidden variables, spooky action at a distance, no-communication, etc.
For various quantum effects that seem to be paradoxes by classical physics what is happening "under the covers"? Does the delayed choice experiment really send information backwards in time? Even if it appears to do so if we can't at least send information back in time with that mechanism isn't it just sophist philosophy at that point?
For my part I'm not smart enough to claim to have answers to anything but my intuition is there are no quantum paradoxes. Delayed choice does not send anything back in time. We don't experience quantum phenomena at the macro scale so our intuition and reasoning are ill-suited to thinking about it. That easily leads us to incorrect conclusions.
I never understood the appeal of title case. It brings nothing valuable, but sometimes leads to stupid mistakes like this, or raises ambiguities that hamper my reading.
I hope the American influence won't make this practice more common in British English. But it's not just about the country: The Washington Post has sane titles, like every British newspaper I've read, while The New York Times Has Elite Titles With Many Big Letters.
I am glad to see that I am not the only one who thinks the same. My mother language doesn't use title case, maybe it's why I find it ugly.
Another thing that I also find really annoying is using commas instead of "and" in headlines. It just makes reading them much harder for no obvious benefit.
While I prefer the aesthetics of only an initial capital in the title, title case in prose helps us distinguish the title from the rest of the sentence.
Technically it is the character with Unicode code point U+1D450. But HN arbitrarily removes it from the string upon submission, so, since we're approximating, C will do.
>This usage can be traced back to the classic Latin texts in which c stood for "celeritas" meaning "speed". The uncommon English word "celerity" is still used when referring to the speed of wave propagation in fluids
I was always taught that it stood for "constant", which is what the speed of light is in every frame of reference and I've never stopped to question it because it made sense. But it seems that usage actually predates Einstein according to the above article. It's interesting how a good story can be used to sell something that's not entirely true and I never stopped to question it.
But light is fast compared to all other things, not just most other things. It is the fastest thing. So, this can’t be it, otherwise Fortran would be traveling back in time… wait, is Fortran traveling back in time?
My immediate guess based on no specific knowledge was “arbitrary constant while they were figuring things out” and it sounds like that’s not far from the truth. The process of discovery is often far more protracted than it seems when one is reading about it decades after the fact.
I've always learned that "speed" is something that can be used to describe an object aka something with mass. When something without mass travels (basically information) you use "celerity", because it's not talking about the "same" thing
I'm not sure why that would be an interesting question. Sure it's probably constant or causality or something else, but really most mathematical symbols exist because someone wrote a paper using that symbol and other people adopted it.
I'd also wondered why r is the correlation coefficient but it turns out it's the "regression" coefficient, as in how strong the regression to the mean is.
A lot of these conventions just develop according to what notation sticks, like how π caught on almost 3 millennia after the ratio was treated as a constant.
And not all of them are even as universal as one might think. mx+c is not.
Charles Hutton used y = ax + b for the equation of a "right line" in xyr 1811 A Course of Mathematics, for example.
"As for c, that is the speed of light in vacuum, and if you ask why c, the answer is that it is the initial letter of celeritas, the Latin word meaning speed."
I definitely though of the programming language at first. Although the speed of light is a bit presumptuous to qualify the speed of C, I now wonder why every benchmark is against C, and not some other language.
Partly because it is fairly fast, partly because, whatever you’re running your language on, chances are better that you can run a C compiler on it than that you can run most other languages.
c is technically the speed of causality. The speed at which perturbations in the fields that make up the universe propagate.
The speed of light is a consequence of this, not the cause. Calling c the "speed of light" is putting the cart before the horse.
Photons (being massless) have 100% of their velocity in the spatial dimensions and no velocity in the time dimension. They move at the maximum speed that any change in the electrostrongweak force can propagate in our universe because they are not free to do anything else.
From a photon's POV a trip across the entire universe happens instantaneously - taking no time whatsoever.
Causation is a bit of a troublesome concept in physics: https://plato.stanford.edu/entries/causation-physics/
I wouldn’t use causality as a foundational concept ontologically.
What’s true is that c doesn’t just apply to the electromagnetic field, but to all fundamental physical fields.
There is a more precise concept of causality in physics that is very much fundamental part of all modern theories.
And what concept would that be?
Einstein causality, i.e that no physical effect propagates faster than light. In QFT it it is modeled by the rule that space-like separated measurements commute.
That merely equates the term "causality" to propagating waves. It doesn't introduce any new concept. Ontologically, there are only quantum fields in space-time. The physical laws governing them imply from their mathematics that they cannot contain any propagations faster than c. But attaching the term "causality" to it doesn't really add anything here.
This does not equate causality with propagating waves. I also did not claim it is a new concept. Instead I said physics has a precise and fundamental concept of causality.
How is it fundamental? You can do all the physics without reference to it. It is a consequence of the equations, not a premise.
Edit: It is not actually a complete consequence, because cause and effect imply a directonality that the equations do not have, being time-symmetric. At the same time, this directionality or asymmetry has no derivable consequences for the practical physics, meaning having the asymmetry doesn't add anything. This is one of the conceptual troubles that introducing "causality" here brings.
It is used in theories that discuss particles with imaginary mass, such as tachyons, that travel backwards in time.
Theories that violate causality are considered unphysical, whereas theories in which measuring such time traveling particle, cannot be distinguished from creating a particle that moves forward in time are not.
Physicists put this into the theories as an assumption at a fundamental level, e.g. they put it as an axiom into axiomatic QFT. This is why it is fundamental. Also arrow of time is something else than Einstein causality.
It sounds like a really nice (and the shortest possible) backronym.
https://en.wikipedia.org/wiki/Backronym
Isn't it supposed to be c for celerity? Edit.. Oh I see. Nvm
"Photons (being massless) have 100% of their velocity in the spatial dimensions and no velocity in the time dimension"
I kinda see what you're trying to say, but these words aren't a particularly good match for the math in special relativity. To an observer, any photon's velocity 4-vector looks like V = (c,c,0,0). That's a "c" in the spatial direction the photon's moving, and a "c" in the time direction. So, plenty of velocity in the time direction.
What is zero is the _proper time_ along a photon's trajectory through space & time. An observer who's co-moving with the photon (call me if you ever meet one, we can write a paper together) would see a) the photon holding still and b) no time passing.
I can't recommend such a co-author. Doesn't get anything done.
special relativity is undefined at v = c. so no from a photons point of view the trip doesn’t happen in an instant nor does the length of the universe shrink to zero. there is no definition for a photons point of view. time dilation and length contraction only apply when comparing a moving frame of reference to one that is at rest and photons have no rest frame.
And when you think about c as the speed of causality, it becomes a lot more obvious why FTL travel/communicate is (almost certainty) impossible without breaking causality....
You are going faster than causality, of course it breaks.
The other option is to break relativity, which is what most science fiction media does, often accidentally.
That sounds like an interesting theory; is it yours, or do you have any citations / references you could share?
If you think it is implied that c stands for the first letter of the word causality, then reading the article should be enough to convince you otherwise.
Einstein published his seminal works in German, and we'd be more likely to have E=mk².
He's just describing Einstein's Theory of Special Relativity.
Huh. I'm admittedly no astrophysicist, but I don't recall encountering this "photons have no velocity in the time dimension" before. Maybe I'm one of today's lucky 10,000[1].
1. https://xkcd.com/1053/
It's not true. It's a mashup of a few ideas that don't belong together.
1. an object at rest has a world line which points (has tangent vectors) in the time dimension
2. light has proper time (dtau) = 0, so clocks moving at the speed of light dont tick
3. the magnitude^2 of an objects 4-velocity is c^2 (objects move through spacetime at c)
4. light has no 4-velocity (because dtau=0, you cant divide by zero)
You can't say (3) means objects have 4-velocity c in spacetime and light has 3-velocity c in space and so that means the time component of 4-velocity for light is zero.
Because light has no 4-velocity.
I enjoyed this video on this topic a lot. Maybe you will too: https://youtu.be/fB8eatgkOyM?si=D9s01MY8jByWREPX
But, it is sort of common to observe the somewhat trippy fact that, unlike matter, photons don’t experience time passing, right? (Although, I will be honest, I could not ever really grok relativity like a physicist. However, I can enjoy the Lorentz factor going to infinity as v goes to c).
From my understanding, it's more correct to say that time is undefined for massless objects.
Through special relativity, our understanding of mass, gravity, and spacetime are linked. If something has no mass, then special relativity can't describe how gravity affects it's spacetime reference.
Remember, however, that this explanation is based on the mathematics that explain the observations we've made or theorized. Just as the map is not the territory, the math is not the universe.
It is, in my opinion, not extremely obvious from the usual descriptions of relativity, but basically when you move faster and faster, you trade your velocity through time for velocity through space. Rather then a funny result, that is the theory.
If you're at rest, you have maximum time velocity (1 you-second per frame-second). If you're at the speed of light, it's zero you-seconds per frame-second.
This is described by the Minkowski space, which is a metric that puts two events the same distance apart in spacetime regardless of reference frame.
Greg Egan's series "Orthogonal" looks into what the universe would look like if time didn't have the opposite sign (so that time is another dimension just like x, y, z). The effects of that one sign change are very wierd.
I'd say it's extremely non-obvious, given "velocity" no longer means distance / time
I can't claim credit for any of this. As others have noted Einstein (and other much smarter people) are responsible.
I like to put it as: Special Relativity is just the Pythagorean Theorem.
It's Einstein's :)
An introduction to general relativity spacetime and geometry by Sean Carrol
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No, there is no causality anymore in quantum physics, since the EPR paradoxon was disproved.
c stands for the latin for for speed of course. causality is immediate, a higher speed than c. because it's logical, not measurable.
> c is technically the speed of causality.
How does this notion reconcile with seemingly instantaneous quantum phenomena like spooky action at a distance?
Quantum entanglement ("spooky action at a distance") doesn't allow for communication, so there's no causality between the particles.
Thanks for the answer. I had forgotten about the No-communication theorem.
This led me into another rabbit hole :-) of why c is 299,792,458 m/s and for example not 499,792,458 m/s or some other value, and the fundamental constants that bring this value. [1]
Is there a current theory that tries to justify those constants that bring the current value of c ? Are those values the ones that must be, for the current Universe to be feasible?
[1] https://arxiv.org/abs/hep-ph/0205340
Veritasium has a few recent videos on Action. In one of them I believe he shows speed of light expressed as one unit of action, which implies that it’s the highest “resolution” any propagation can resolve at based on the fundamentally smallest path integral anything can traverse, or something.
I'm not sure if there is a good theory on why it ends up being this speed, but if any of the constants were even slightly different we wouldn't be in this universe to talk about it.
https://en.wikipedia.org/wiki/Fine-tuned_universe
The speed of light is 1c and is a fundamental constant.
Humans choose to express it in metres and seconds.
A meter is huge if you compare it to the Planck length. Humans are pretty big creatures compared to fundamental particles, so we have a big basic unit of length. But seconds are gargantuan, because humans are absolutely glacial if you compare them to the time it takes light to travel a Planck length.
It's like a continental plate asking why humans zip around so fast.
> The speed of light is 1c and is a fundamental constant.
Yes, but why is the value that it is and not higher or lower? From my (basic) research it seems, it could be plus or minus 20% a different value, and the current Universe would still be feasible.
Well, it has to be _some_ value, right? I mean, if we were in a universe where it was 20% greater, you would be asking the same questions.
No, the point is that if it was 20% bigger we would not be here to ask those questions :-) Stars fusion or weak atomic interactions would not work. Maybe Hari Seldon decided....
But you said in your comment that "it could be plus or minus 20% a different value, and the current Universe would still be feasible"
That touches on a long-running very complicated debate around quantum mechanics, hidden variables, spooky action at a distance, no-communication, etc.
For various quantum effects that seem to be paradoxes by classical physics what is happening "under the covers"? Does the delayed choice experiment really send information backwards in time? Even if it appears to do so if we can't at least send information back in time with that mechanism isn't it just sophist philosophy at that point?
For my part I'm not smart enough to claim to have answers to anything but my intuition is there are no quantum paradoxes. Delayed choice does not send anything back in time. We don't experience quantum phenomena at the macro scale so our intuition and reasoning are ill-suited to thinking about it. That easily leads us to incorrect conclusions.
Sure, but why did Einstein call the speed of light c?
I think the article explains that.
is that a highly technical way of saying WE think c is the speed of light, because that's all WE can measure?
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Please fix the title, it's _c_, not _C_.
I never understood the appeal of title case. It brings nothing valuable, but sometimes leads to stupid mistakes like this, or raises ambiguities that hamper my reading.
I hope the American influence won't make this practice more common in British English. But it's not just about the country: The Washington Post has sane titles, like every British newspaper I've read, while The New York Times Has Elite Titles With Many Big Letters.
I am glad to see that I am not the only one who thinks the same. My mother language doesn't use title case, maybe it's why I find it ugly.
Another thing that I also find really annoying is using commas instead of "and" in headlines. It just makes reading them much harder for no obvious benefit.
While I prefer the aesthetics of only an initial capital in the title, title case in prose helps us distinguish the title from the rest of the sentence.
There are more suitable typographical techniques of accomplishing the same result.
Technically it is the character with Unicode code point U+1D450. But HN arbitrarily removes it from the string upon submission, so, since we're approximating, C will do.
>This usage can be traced back to the classic Latin texts in which c stood for "celeritas" meaning "speed". The uncommon English word "celerity" is still used when referring to the speed of wave propagation in fluids
not to mention the more common "acceleration"
Yes, the very next sentence in the article:
The same Latin root is found in more familiar words such as acceleration and even celebrity, a word used when fame comes quickly.
yes! and that is composite
* "a-/ad-" towards
* "celeritas" speed
the second derivative, of sorts:
towards+speed
Indeed, and c_s ("c subscript s") is commonly used to denote the speed of sound.
I was always taught that it stood for "constant", which is what the speed of light is in every frame of reference and I've never stopped to question it because it made sense. But it seems that usage actually predates Einstein according to the above article. It's interesting how a good story can be used to sell something that's not entirely true and I never stopped to question it.
C is for "Cochranes", named after Zefram Cochrane
I thought it was because C is fast (compared to most other languages)
But light is fast compared to all other things, not just most other things. It is the fastest thing. So, this can’t be it, otherwise Fortran would be traveling back in time… wait, is Fortran traveling back in time?
C is for cookies, and that's good enough for me!
My immediate guess based on no specific knowledge was “arbitrary constant while they were figuring things out” and it sounds like that’s not far from the truth. The process of discovery is often far more protracted than it seems when one is reading about it decades after the fact.
It wasn't the symbol for the speed of light, it was the symbol for the Lorenz Constant.
Cool to see a local school on here.
Off-topic but their botanical gardens and Cactus/Desert garden is a really enjoyable afternoon.
I wonder whether this is the Philip Gibbs that set up viXra.
I've always learned that "speed" is something that can be used to describe an object aka something with mass. When something without mass travels (basically information) you use "celerity", because it's not talking about the "same" thing
So c = celeration, the derivative of acceleration.
A little too neat. It has the distinct aroma of lies told to children. (Not that I would have detected it myself, as a child.)
Somewhat off-topic, but here's "A joke about measurement": https://www.youtube.com/watch?v=KmfdeWd0RMk
> Why is C the symbol for the speed of light?
I'm not sure why that would be an interesting question. Sure it's probably constant or causality or something else, but really most mathematical symbols exist because someone wrote a paper using that symbol and other people adopted it.
Previous discussion:
https://news.ycombinator.com/item?id=36904892 (45 comments, 139 points)
Okay, now why is m slope?
I'd also wondered why r is the correlation coefficient but it turns out it's the "regression" coefficient, as in how strong the regression to the mean is.
A lot of these conventions just develop according to what notation sticks, like how π caught on almost 3 millennia after the ratio was treated as a constant.
And not all of them are even as universal as one might think. mx+c is not.
Charles Hutton used y = ax + b for the equation of a "right line" in xyr 1811 A Course of Mathematics, for example.
I used y = ax + b all the time in school. This is the first time I encounter mx + c.
For a Basque speaker as me, m was ideal because malda in Basque means... slope :)
Okay, now why is m slope?
the great divide between US and Europe :D should be a - a, b, c, d... why m though, indeed?
Wait, is m slope? I learned it with k (for coefficient) for the slope, and m for the intercept (I don't know why m in that case though).
Kind of reminds me of a mountain you're going to climb :)
From a bit of googling I see some people say it's from French "monter", meaning to climb, which does come from the same root as English "mountain".
I always thought it was because it's not the speed of LIGHT
It's the speed of causality
But it still blows my mind the universe expands faster than C
https://en.wikipedia.org/wiki/Cosmological_constant#/media/F...
Because C++ wasn't invented yet.
It is because light is the only part of the radiation spectrum you c.
_C_elerity?
Celerity is the new FLASH villian? Haha.
as a programmer I would answer: well c ist the fastes way to construct a complete bogus programm :)
Could also stand for Speed of Causality.
A and B were already used. Somewhere.
B non-ironically was (I guess) - it means magnetic field.
A, no idea.
Also might I add the speed of light is (lower-case) c, not C
Magnetic Vector Potential?
Wouldn't a have been used for acceleration?
An interesting question : )
Because C++ is object oriented.
Because god coded it on C
Thought something similar, it's all because they wrote C instead of the actual c in the title
I realise now I had probably only thought of c as a natural companion to v because of Qwerty keyboards...
c. Not C
Neither. It should be https://www.compart.com/en/unicode/U+1D450
But HN is broken and the character disappears upon submission, so we have to approximate it with a symbol that looks similar. C is similar enough.
"As for c, that is the speed of light in vacuum, and if you ask why c, the answer is that it is the initial letter of celeritas, the Latin word meaning speed."
Isaac Asimov in "C for Celeritas (1959)"
'https://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLig...
Because it’s the fastest programming language
Yep but some are claiming this makes the speed of light incredibly unsafe and unpredictable.
A small but loud group of scientists are working to replace c with a crab emoji in most literature going forward.
Travelling at c is UB.
>unsafe and unpredictable.
Just llike the Electron.
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I definitely though of the programming language at first. Although the speed of light is a bit presumptuous to qualify the speed of C, I now wonder why every benchmark is against C, and not some other language.
Partly because it is fairly fast, partly because, whatever you’re running your language on, chances are better that you can run a C compiler on it than that you can run most other languages.
Wrong answers only
You need "C" to be the symbol for the speed of light to make the joke from Animanics work.
Link? I was a big animaniacs fan, but not recalling this one.
https://www.youtube.com/watch?v=rsyJX3sESjs
"How can I eat cookies when the theory of relativity has escaped me?!" is a pretty good line
The one where they spell acme backwards?
e m c α
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They used lowercase on the actual page, the HN title is what's wrong.
Oh man, maybe HN should not allow commenting until at least the link is clicked.
That's celerious
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'cause you don't c it coming
Because of the language
C you later?
I thought c stood for clock speed and that is how we know we are in a simulation.
> Why is C the symbol for the speed of light?
Because C++ and Rust wasn’t invented when they formalized it! … I’ll see myself out
C is the Roman numeral representing 100. You can't go faster than 100% of the speed of light. QED.
Quod Erat Demonstrandum.
The 'short version' is very well written and to the point. (I didn't read the long version, so my lack of comment on that isn't a criticism of it)