[RightWhale]

We should be more demanding of our science teachers. We know what the Theory of Relativity says. Anybody can see that the speed of light applies to light. Unless we are bodies of light we shouldn't be concerned with the ToR.

Maybe we are bodies of light, although there is little evidence of that.

[Jedi Master Pikachu]

Doesn't it also apply to anything with mass? Some hypothesizers (theorists?) have come up with the idea that if mass could be eliminated then something could travel past c. Others would manipulate gravitation or expand/contract spacetime.

Notably, only travel at c is supposedly prohibited, but travel faster or slower could happen (hence tachyons).

[burzum]

We should be more demanding of our science teachers. We know what the Theory of Relativity says. Anybody can see that the speed of light applies to light. Unless we are bodies of light we shouldn't be concerned with the ToR.

That is not what the theory of relativity says at all. The special theory of relativity has two conjectures (I'm not going to go into the general theory here): 1) The laws of physics are constant in all inertial reference frames, and 2) the speed of light is constant regardless of the motion of the observer.

If you want to take this to a logical conclusion you will find that it will take an infinite amount of energy to accelerate any object to the speed of light.

[Aussieteen]

Firstly, to those of us talking about FTL travel. The Alcubierre drive was an interest of mine a bit back, and, although it requires the manipulation of negative energy, it's still interesting to look at.

http://en.wikipedia.org/wiki/Alcubierre_drive

Light has no mass, and yet it's constricted to travel at lightspeed. And, so far as conservation of energy and relativity are concerned, we're fairly close to bodies of light. e=mc^2, so mass can be converted to energy (the most prominent example of this being antimatter, where an electron and positron can annihilate one another, forming a pair of what tend to be gamma-ray photons).

The problem with exceeding the speed of light is that it's an inverse relationship, as it gets higher, or a hyperbola on a graph. As your speed increases to near-c speeds, a certain portion of your acceleration is converted to mass (of course, that's a simplified explanation, so don't go attacking it for the various.. things I've left out).

As an arbitrary example, acceleration from .9 c to .99 c, for a single atom, might require a few million newtons. (Again, arbitrary. I'm tired, and doing the math right now is beyond me). Acceleration from .99 c to .999c might require the exact same amount of energy, despite the fact that we're accelerating about a tenth as much.

You can't actually *reach* the speed of light if you have mass, as an infinite amount of energy is required to do so. The speed of light is only there as the 'universal speed limit', something we believe nothing can exceed. (although wormholes and Alcubierre drives could *effectively* exceed light, in that they would manipulate the fabric of the universe around them to achieve this travel, the atoms of the spaceship would still not be able to reach, or exceed lightspeed.)

Besides, time dilation is plenty good, if you want to send out colonies. I see the most viable plan for long-term colonisation the construction of massive colony ships, with equally massive engines, reaching relatavistic speeds to make time pass more slowly for the inhabitants inside. Of course, there are a HOST of problems that go along with that one, but it doesn't really require any new discoveries.

After all, the universe has a long time left to go. Even if we put the maximum speed of humanity at .1 c, we could still slowly colonize the galaxy, and eventually the majority of the known universe.