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[kaijyuu]

There isn't one. If there's a force acting on it, there's drag.


Unless you're talking the speed of light limit, at which point the "max terminal velocity" would be c. Sort of an irrelevant distinction because the math works out the same either way, applying time and space dilation and whatnot.

[Neonivek]

Then what about a diminishing factor. Where something is potentially infinite but realistically limited.

[kaijyuu]

Yeah I think you're talking about relativistic diminishing returns, which is kinda irrelevant since space contraction "makes up" for the non-linear speed gain.

Gravitational acceleration isn't different from any other form of acceleration. That's why general relativity exists.

[Mech#4]

Is the reason why you can't go faster then the speed of light because it would be like trying to break the sound barrier with the build up of light waves instead of sound waves?

[da_nang]

There is no terminal velocity in a (perfect) vacuum. Terminal velocity is when the acceleration and the drag from friction become equal. Zero drag = infinite terminal velocity.

In a fantasy environment with constant gravity, an object would speed up indefinitely and approach c.

Just making sure it's said, the force of gravity inside the earth is not constant, but instead decreases roughly with the cube of the distance from the center of the earth.

Actually, inside the Earth, assuming uniformly mass-distributed sphere, the gravity is directly proportional to the distance, G ∝ r. This is also similar to the electric field strength inside a solid nonconducting sphere since Coulomb's law is similar to Newton's law of gravitation.

Is the reason why you can't go faster then the speed of light because it would be like trying to break the sound barrier with the build up of light waves instead of sound waves?

Unlike sound, there isn't a medium for it (AKA the aether back in the old days). So the reason isn't down to breaking a "light barrier". No, the reason comes down to relativity and the how space-time works. However, Einstein's theories only say you can't accelerate to c and beyond. It doesn't prevent objects to be already traveling faster than c.

[kaijyuu]

Is the reason why you can't go faster then the speed of light because it would be like trying to break the sound barrier with the build up of light waves instead of sound waves?

Mmmm, no. The speed of light limit is rather arbitrary and doesn't have any "reason" behind it except because it exists. Though, if my understanding is correct, without it, time wouldn't exist (everything would happen instantaneously). Could be wrong on that point.

It has a lot of weird, unintuitive consequences though. Like time dilation, space contraction, and of course, the speed limit itself.

[Shadowlord]

Unless you're talking the speed of light limit, at which point the "max terminal velocity" would be c. Sort of an irrelevant distinction because the math works out the same either way, applying time and space dilation and whatnot.

It isn't c, since you can't ever reach c if you have mass. If you're moving through something with no density (or moving through nothing nothing), your terminal velocity should be simply undefined. See http://en.wikipedia.org/wiki/Terminal_velocity for an equation for terminal velocity that ignores buoyancy, which divides something by the drag coefficient times the density of the fluid through which the object is falling times the projected area of the object. Since the density is 0, you're dividing by 0. (Even if you try to argue that that gives infinity, which it doesn't, you can't ever reach infinite velocity, as you can't ever reach c, which is decidedly non-infinite but requires infinite energy or zero mass to reach)

Or, in words: "In fluid dynamics, an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving." That definition assumes the object is under the effects of an acceleration force (Usually gravity). If there is no restraining force, and you're accelerating, there is no velocity at which your speed will become constant because there is no force opposing your acceleration.

[kaijyuu]

Well yeah, limits In a fantasy situation with constant gravitational acceleration and zero drag, it'd approach c but never quite make it, simply because "infinity" takes a really damn long time.

[ChairmanPoo]

Is the reason why you can't go faster then the speed of light because it would be like trying to break the sound barrier with the build up of light waves instead of sound waves?

No, because in other media (such as water) where light travels more slowly, you CAN beat the "speed of light". It's the source of Cherenkov's radiation (The blue light in fission reactors)

[Another]

And by the way in perfect vacuum any particle that bears electric charge would radiate Cherenkov photons and slow down if it was moving faster than c. There are also reasons to think that electrically neutral particles that can interact with normal matter would also indirectly emit Cherenkov radiation. This is one more hard problem with ever going faster than light.

[olemars]

Is the reason why you can't go faster then the speed of light because it would be like trying to break the sound barrier with the build up of light waves instead of sound waves?

Mmmm, no. The speed of light limit is rather arbitrary and doesn't have any "reason" behind it except because it exists. Though, if my understanding is correct, without it, time wouldn't exist (everything would happen instantaneously). Could be wrong on that point.

It has a lot of weird, unintuitive consequences though. Like time dilation, space contraction, and of course, the speed limit itself.

The value of c in vacuum does have consequences. If it was just a tiny bit different it would have serious effects on the structure of the universe. There's a convoluted philosophical argument to go with it that essentially says the speed of light is what it is because if it wasn't we wouldn't be around to measure it.

[Graknorke]

Is there actually any proof that you can't go faster than the speed of light?
It's so widely accepted, but I'm pretty sure that nothing has ever been accelerated and measured to a speed anywhere near.

[10ebbor10]

Is the reason why you can't go faster then the speed of light because it would be like trying to break the sound barrier with the build up of light waves instead of sound waves?

Relativistic arceleration says that the faster you go, the more energy you need to arcelerate. In order to reach light speed you'd need an infinitive amount of energy. Photons are able to achieve this speed, because they have no mass.

Is there actually any proof that you can't go faster than the speed of light?
It's so widely accepted, but I'm pretty sure that nothing has ever been accelerated and measured to a speed anywhere near.

We're able to measure the small differences in energy needed, and time dillation, and extrapolating leads us to believe this is indeed the case. (These changes are quiet important. GPS sattelites are modified to account for them, for example.)

Also, observing stars, galaxies and other spatial objects seems to confirm this statement.

[Karlito]

Is there actually any proof that you can't go faster than the speed of light?
It's so widely accepted, but I'm pretty sure that nothing has ever been accelerated and measured to a speed anywhere near.

Protons in the LHC travel at something like .999c. General Relativity has been experimentally verified in hundreds of different ways.

[da_nang]

Is there actually any proof that you can't go faster than the speed of light?
It's so widely accepted, but I'm pretty sure that nothing has ever been accelerated and measured to a speed anywhere near.

LHC would like to have a word about that.

In any case, when it comes to proofs, there have been several experiments that test the validity of the theory of relativity.

But as usual, one antithesis is all that is needed to necessitate an adjustment or, if needed, a paradigm shift.