Speed of Light Barrier

The reason light has that speed is more to do with human measurements than anything else.
In special relativity light moves equally in space and time, so for every 1m light covers in time, it covers 1m in space.
So it's speed is: 1m/1m = 1.Similarly for every 300,000,000 meters in time light covers it covers 300,000,000 meters in space.
So again this is: 300,000,000m/300,000,000m
However, because of the way we see the world, humans call 300,000,000 meters in time 1 second.
So this speed becomes 300,000,000m/1s = 3x10^8 m/s.It isn't that light's speed is arbitrary or "without reason" it's because us humans don't measure time and space equally.
Our time measurement, the second, is way too big compared with our space measurement.There is a similar reason for all the constants.

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Yes, and the whole question is why is the number 3x10^8 and not say 2x10^8. The units are a given, it's the magitude that is of interest.

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For the reason I stated.
We humans simply invented a measurement of time called the second and a measurement of space called the meter.
The only reason there is a "speed of light" is because the temporal measurement is so mismatched from the spatial one.
That is the explanation of the magnitude, our disproportionate measurement system.

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If you mean, why they have their given dimensions, then this is obvious. Their magnitudes are not obvious.

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No also their magnitudes, for instance G only comes about because our unit of mass is so small compared with our unit of space and extremely small compared with our unit of time.
i.e. kg < meter < second.
The constants are there because of errors in the formulation of our measurement system.

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What I don't get is why the length of that vector is the length that it is. Or another way to restate the same question (I think) is, why does OUR space-time necessitate a "c" of 3x10^8m/s in order for
the space-time interval to be invariant?

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This is actually what I'm talking about. I'm not saying if you choose any arbitrary measurement system you can get any speed you want.

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although it's possible to measure the speed of light as 1(length unit "A")/(time unit "B")

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This is essentially the crux of the problem.
In special relativity there is no space and time, only spacetime.
Similarly velocity should be measured not in space and time units but in a single spacetime unit.
Of course this unit can be arbitrary, just as space and time units can be arbitrary, but the point is that there is a single unit for spacetime.
Making a space unit and a time unit separates them out and creates constants like "c".
If we measure light's speed in a single arbitrary spacetime unit it is always 1."c" can be best thought of as a constant which modifies our inadequate Newtonian space and time units.This message has been edited by Son Goku, 07-19-2005 02:01 PMThis message has been edited by Son Goku, 07-19-2005 02:34 PM

I was only speaking of the constants that appear when the Newtonian framework is kept in other theories.i.e., the coloumb, "c", "G", "k", e.t.c
In other words the most common constants, relation ones.Not literally every constant such as the fine structure constant.I'm aware they aren't explained.

No, I'm not arguing anything.I'm just saying in the context of special relativity "c" can be explained by the fact that light forms a 45 degree Minkowski angle to the any axis of any observer.There are arguements as to why a change in the fine structure constant wouldn't literally translate as a change in "c" and it isn't determined if alpha has actually changed, but this is the domain of quantum field theory and I'm only discussing Special relativity, in which "c" has no meaning.

Yeah, I know. I was just saying that for shorthand.Technically light's speed comes about from the fact that light is described with a null vector.
Since I was discussing Minkowski space orthogonality is largely preserved so I was just using the common "Schutz" description.As for Quantum Theory, it isn't really shown yet that it changes the picture of light's velocity's numerical value, so I choose to leave it out.

Yes, I know it isn't because of him.
It's convention, but it is usually termed the Schutz description.
Which doesn't imply he came up with it, it just arises from the popularity of his book as an undergraduate text.
I wasn't claiming that "Bernard" causes light to be a null ray, I was saying that the Euclidean representation of Minkowski space is called the Schutz description.Basically because the basis vectors are constant I can use this Euclidean terminology, even though it is incorrect.

Yeah, due to the fact that it is a rare mix of a physical and a mathematical view on the subject.D'Inverno is definitely better if you want physical exposition though.Carroll and Hartle are the two major new ones.Hartle emphasizes physics and Carroll emphasizes maths.

Hello V-Bird It is more than a non-starter, it is directly contradicted by observational evidence. Gravity operating faster than light would certainly require a rewrite of General Relativity. Since Special Relativity does not describe gravity a rewrite of gravity would be irrelevant to it. Gravity has no relation to the Heisenberg uncertainty principle which is a result of Quantum statistics.

I am not sure how to present all gravitation based experiments and their results over the last eighty years in digestible format. It is similar to asking me to show you the evidence that energy conservation is never violated. It follows from the fact that it has never been observed to occur at all and that several other experimentally verified principles forbid it. Since General Relativity forbids gravity to move faster than light (in so far as a speed of gravity is defined in the theory), any experimental support of General Relativity can be seen as evidence against the proposal. First of all, Faster-than-light gravitational exchange is not a known or supported theory or effect, so referring to it in a concrete manner and ascribing it properties such as "it is a quantum scale event" is very vague, especially when it is supposed to contradict an explicitly quantum phenomena. This would be similar to me announcing that the Son Goku particle has spin 3/2 and can circumvent the Rita-Schwinger equation. Secondly, assuming this effect is a coherent concept (since I'm in a generous mood) how do the position and momentum operators resulting from the theory commute?