Maximum speed possible

[PhysicsNut]

Is there any theory explaining why 299,792,458 m/s is the speed at which an object with no mass travels, or why there is a limit at all?

 

 

[insane_alien]

have a look at maxwells equations.

[ajb]

It is all contained in special relativity. As insane_alien suggests, Maxwell's equations are a relativistic theory. More importantly, they have wave solutions that necessarily travel at c in vacuum. The quanta of which are photons.

[xus]

as Einstein discoverd the speed of light is relative so if you are flying with the speed of light holding a mirror in front of you you would see your face

[steevey]

Light is pure momentum, but light is also another form of matter. Matter can't travel past or at the speed of light, because that would require the matter to be pure momentum. In a less accurate way, it's like putting paper in water. You can put as much water as you want on the paper, but the paper will never become water, unless you actually go and change its structure, which is what you'd have to do with matter to make it light. And look around, most of the universe that you see is made of matter. There might be forces or things that travel past the speed of light, but we don't know how to detect them. Even the reason gravity travels at the speed of light is because it's carried through gauge bosons, which are particles of pure momentum, like light. Momentum is also different than energy, just in case you didn't know. Technically, light it's pure "energy" because it's a particle, and can be identified at a fixed magnitude.

Edited December 9, 2010 by steevey

[md65536]

I have a fairly solid understanding of why the speed of light is a cosmic speed limit,

but as for the value of c itself, I have no idea.

 

Is this value connected in any way with other fundamental constants?

Are the fundamental constants of the universe pretty much arbitrary? c is based on measurements of time and length, but would it work equally well if it was a different ratio? I don't see why not.

 

There are theories involving infinite universes each with different values for the fundamental constants. People ponder questions like "Which would support the formation of galaxies? Which would support life?" and stuff.

 

Personally, I would think that if we finally found a Unified Theory of Everything, that all of the fundamental constants could be derived from each other. However, I've seen no evidence that that is true. I've never found a plausible explanation of why the speed of light is the value that it is.

 

 

 

 

 

Though...

you can get around this by using units of distance and time so that c=1, which is the sensible thing to do when dealing with light. Eg. instead of m/s, express it in lightyears/year. This defines distance in terms of the speed of light; you could also do the opposite and define a unit of time based on a unit of length. Then to make sense of the value of the speed of light, you would need to find a significant, non-arbitrary unit for either length or time. The Planck length is the only one I can think of, but that itself is based on light. Perhaps this line of reasoning could lead to an explanation, but the only sense I can make of it is that it just comes back to "an arbitrary value."

[Schrödinger's hat]

As md said. It's defined. It is more sensible to ask why things happen at the rate they do given how big they are, (which I cannot answer). Maybe if things were bigger, we'd just consider that small and be in the same position.

What I find more puzzling are the fundamental constants such as the Fine structure constant. These don't have units and so cannot be defined, but they also have very specific numerical values as far as any testable theory goes.

 

As to why there is a limit, it's a bit like asking why do things fall. We know fairly precisely how they fall, and what is correlated to falling, but why? Physics isn't up to that yet. Even when it is, we will merely be putting two previously separate whys into the same why.

The only semblance of an answer would still be well within the realm of philosophy.

Edited January 29, 2011 by Schrödinger's hat