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.
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.
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.
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.
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.
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.
Einstein published his seminal works in German, and we'd be more likely to have E=mk².
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.
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.
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.
c stands for the latin for for speed of course. causality is immediate, a higher speed than c. because it's logical, not measurable.
How does this notion reconcile with seemingly instantaneous quantum phenomena like spooky action at a distance?
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?
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.
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.
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 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.
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.
not to mention the more common "acceleration"
The same Latin root is found in more familiar words such as acceleration and even celebrity, a word used when fame comes quickly.
* "a-/ad-" towards
* "celeritas" speed
the second derivative, of sorts:
towards+speed
Off-topic but their botanical gardens and Cactus/Desert garden is a really enjoyable afternoon.
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.
https://news.ycombinator.com/item?id=36904892 (45 comments, 139 points)
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.
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.
the great divide between US and Europe :D should be a - a, b, c, d... why m though, indeed?
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...
A, no idea.
Also might I add the speed of light is (lower-case) c, not C
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.
Isaac Asimov in "C for Celeritas (1959)"
'https://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLig...
Because C++ and Rust wasn’t invented when they formalized it! … I’ll see myself out
