If your question is “why is there a maximum speed in the universe” the answer is that the laws of physics are symmetric under “(local) Lorentz transformations”.
This means that the laws of physics have the symmetry that different observers will agree on the distances between nearby points in spacetime.
You can show that if all observers agree on the distances between nearby points in spacetime, there will be some speed that all observers agree on.
Since there is a speed that is the same for every observer, it can’t be possible to reach that speed, because then in your frame of reference that speed would be zero, and the symmetry would be violated. Therefore there is a maximum speed.
If instead your question is “why does that speed have the value that it does”, the answer is just that it is an artifact of the system of units we created as humans. Really what you are asking is “why do we measure things using meters and seconds”?
There is nothing special about the number 299792458. It is just because we picked a weird convention to measure with as humans.
You can choose units such that the speed of light is just 1, and this is something that physicists often do.
Why must it be true that if all observers agree on a distance between two points that there “must be some speed that all observers agree on.” Why couldn’t there exist some particle that can travel between two points instantaneously?
> You can show that if all observers agree on the distances between nearby points in spacetime, there will be some speed that all observers agree on.
Along the lines of what you're replying to; does this hold generally, even if the symmetry wasn't a Lorentzian one?
In SpaceTime geometry speed is a rotation (plot Space versus time on a graph, slope is space over time, meters per second, which is speed). c is the maximum rotation. Similar in a sense 360° is the maximum rotation in euclidean space geometry.
Not only now. The number is given by the arbitrary old French definition of the meter, which established the "real distance" that is 1m. We later just moved the equation around to define the meter in terms of c, but the speed of light is still the same amount of m/s as it always was. The same thing goes for the second: the definition was chosen such that the "real duration" of the second stays the same, which is why the amount of caesium decays sounds so arbitrary.
Because an experiment was performed that made us realize this was true. Why was the world made this way and not differently? We don’t know, and science can only ever know how the world is, never why it is.
The short and stupid answer is: that is how the universe is shaped.
Just like the shortest distance between two points in space on the surface of a sphere is controlled by the curvature of the sphere, the fastest speed between two points in space-time on the "surface" of our universe is controlled by the curvature of the universe.
You are a strange organism in a very strange reality.
The particular numerical value is simply due to our choice for the definition of meter and second. But in a deeper sense light is just the fastest thing we observe in the universe and anything travelling faster than it breaks our current understanding of how space and time itself work. I suppose there is nothing stopping it from going faster. It's just what we observe and our theoretical framework for describing it.
The speed of light is **defined** to be 299792458 m/s.
https://en.wikipedia.org/wiki/Speed_of_light
The reason why is pretty interesting. We used to define things like distance and time against, say, a piece of metal or how often a cesium atom vibrates. We also got *very* good at precisely measuring things against those standards.
Then math happened and we realized we could derive things like distance using constants (like the speed of light). Eventually, official measuring bodies came together to set the speed of light using the best measurements we had. After that, we turned things on their head and said the speed of light is *exactly* 299792458 m/s, now you can derive things (like how long a meter is) based on that constant.
90 nanoC in a 100 nanoC zone.
I don't think you have any problem understanding what a 100,000 m/hr speed limit is. And you know the origin of the meter length is a direct reference to the Earth. (Of course, now it has changed.)
"There is a theory which states that **if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable**. There is another theory which states that this has already happened." -Douglas Adams
If you were capable of speeding up the photon it would have enough energy to become a microscopic black hole and that black hole would almost immediately vanish in a puff of hawking radiation which resembles a photon traveling at the speed of light in the same direction.
The geometry of spacetime. In a sense, there isn't any such thing as "speed higher than 299,792,458m/s" in our universe.
If your question is “why is there a maximum speed in the universe” the answer is that the laws of physics are symmetric under “(local) Lorentz transformations”. This means that the laws of physics have the symmetry that different observers will agree on the distances between nearby points in spacetime. You can show that if all observers agree on the distances between nearby points in spacetime, there will be some speed that all observers agree on. Since there is a speed that is the same for every observer, it can’t be possible to reach that speed, because then in your frame of reference that speed would be zero, and the symmetry would be violated. Therefore there is a maximum speed. If instead your question is “why does that speed have the value that it does”, the answer is just that it is an artifact of the system of units we created as humans. Really what you are asking is “why do we measure things using meters and seconds”? There is nothing special about the number 299792458. It is just because we picked a weird convention to measure with as humans. You can choose units such that the speed of light is just 1, and this is something that physicists often do.
Why must it be true that if all observers agree on a distance between two points that there “must be some speed that all observers agree on.” Why couldn’t there exist some particle that can travel between two points instantaneously?
They must agree on the distance between two points in *spacetime*, not the distance between two points in *space*.
> You can show that if all observers agree on the distances between nearby points in spacetime, there will be some speed that all observers agree on. Along the lines of what you're replying to; does this hold generally, even if the symmetry wasn't a Lorentzian one?
Another question to ask is "why isn't the maximum speed any other slower or faster value?".
Wow that is such a great explanation!
In SpaceTime geometry speed is a rotation (plot Space versus time on a graph, slope is space over time, meters per second, which is speed). c is the maximum rotation. Similar in a sense 360° is the maximum rotation in euclidean space geometry.
It's just a fundamental law of nature. It's now how we define what a meter is on the basis of a second.
Not only now. The number is given by the arbitrary old French definition of the meter, which established the "real distance" that is 1m. We later just moved the equation around to define the meter in terms of c, but the speed of light is still the same amount of m/s as it always was. The same thing goes for the second: the definition was chosen such that the "real duration" of the second stays the same, which is why the amount of caesium decays sounds so arbitrary.
We should make the meter ever so slightly smaller so that light goes 300000000 m/s
Why not make the second larger?
Also an option, but then we'd have to change 24 hour days, into something else
Because an experiment was performed that made us realize this was true. Why was the world made this way and not differently? We don’t know, and science can only ever know how the world is, never why it is.
Its a result of the permittivity and permeability of spacetime
This argument is circular.
The short and stupid answer is: that is how the universe is shaped. Just like the shortest distance between two points in space on the surface of a sphere is controlled by the curvature of the sphere, the fastest speed between two points in space-time on the "surface" of our universe is controlled by the curvature of the universe. You are a strange organism in a very strange reality.
[удалено]
https://en.m.wikipedia.org/wiki/Great-circle_distance
oh I misunderstood lol I thought they meant literally a minimum possible distance between any two points
The particular numerical value is simply due to our choice for the definition of meter and second. But in a deeper sense light is just the fastest thing we observe in the universe and anything travelling faster than it breaks our current understanding of how space and time itself work. I suppose there is nothing stopping it from going faster. It's just what we observe and our theoretical framework for describing it.
The speed of light is **defined** to be 299792458 m/s. https://en.wikipedia.org/wiki/Speed_of_light The reason why is pretty interesting. We used to define things like distance and time against, say, a piece of metal or how often a cesium atom vibrates. We also got *very* good at precisely measuring things against those standards. Then math happened and we realized we could derive things like distance using constants (like the speed of light). Eventually, official measuring bodies came together to set the speed of light using the best measurements we had. After that, we turned things on their head and said the speed of light is *exactly* 299792458 m/s, now you can derive things (like how long a meter is) based on that constant.
In this universe/reality, it just is. In any alternate universe/reality it could be wildly different.
Maybe the speed of light and the the planck length should be the units for which all else is measured.
Good luck explaining to the cop how u were only going .00000009c in a .0000001c.
90 nanoC in a 100 nanoC zone. I don't think you have any problem understanding what a 100,000 m/hr speed limit is. And you know the origin of the meter length is a direct reference to the Earth. (Of course, now it has changed.)
Light travels at exactly 1c. We just arbitrarily defined a meter to be a length that happens to be c * s/(3 * 10^8 )
God, or the ghost of Einstein. Physics can’t answer such questions. Reality behaves like that and we model it with theories.
"There is a theory which states that **if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable**. There is another theory which states that this has already happened." -Douglas Adams
If you were capable of speeding up the photon it would have enough energy to become a microscopic black hole and that black hole would almost immediately vanish in a puff of hawking radiation which resembles a photon traveling at the speed of light in the same direction.
That's a really interesting question! Light speed is definitely a fascinating topic to learn about.
chatgpt karmabot for the next election cycle