5 ms·

> we currently know of no natural phenomena that would hint at the possibility of faster-than-light travel and in fact have good reasons to believe that it is i

• rfrey 10y ago
  You are being downvoted for your misunderstanding, which is too bad. In a nutshell, no matter how much energy you pump into your system, you will never go faster than the speed of light, relative to any other viewpoint. That is, you would never appear to go faster than the speed of light to anyone - including somebody travelling at the same speed as you in the opposite direction.
  • sp332 10y ago
    The universe outside your window won't be passing by faster than the speed of light either. But that's a bit moot, since Lorentz contraction will make the distances in your line of travel shorter. Also time will pass more slowly for you. So subjectively, it's true that you can get anywhere in an arbitrarily small amount of time if you have arbitrarily large amounts of energy, but the rest of the universe will still see you only approaching the speed of light.
  • panic 10y ago
    No, b6 has it right, you can travel as fast as you want. The universe will get squished along your direction of travel, effectively increasing the speed of light (relative to the distance you're traveling) as your speed increases.
    • madaxe_again 10y ago
      Relative being the key word. With a sufficiently fast ship you could fly across the universe in your lifetime - but you'd get home to find the sun a cinder and earth long gone.
      • scott_s 10y ago
        This is not true. Even in your frame of reference, you cannot go faster than the speed of light.
    • scott_s 10y ago
      You certainly cannot travel as fast as you want. The speed of light is the speed limit of the universe, to all observers.
• Cybiote 10y ago
  You can't travel as fast as you want because it will take ever larger amounts of energy to accelerate each fraction of a percent closer to the speed of light. You're effectively bounded above by the speed of light.
  • Cybiote 10y ago
    Maybe I need to clarify? A certain amount of energy must be expended to reach a particular velocity. For a relativistically relevant velocity, kinetic energy is given as: mass * c^2 * (1/sqrt (1 - v^2/c^2) - 1); it's clear that v will never reach c. For an example of how things can escalate: an object massing 1 kiloton traveling at 90% the speed of light has 4x the kinetic energy as the same mass at 65% (for context, a 1kton object at 0.65c has ~50x the energy as was used in 2013). From 90% -> 99% it's a ~5x increase. And from 99% -> 99.9% it's 3.5x. So just a 0.9% increase in speed has almost as much impact on energy as the 25% increase at a lower velocity.
• geofft 10y ago
  Relativity means that there's no difference between "I'm going at speed V forwards" and "That object is going at speed V backwards" (assuming neither of you is accelerating). In fact, the only way to tell your own speed is to look at the speed of the world around you, and reverse the direction. Since it's impossible for you to observe anything else going faster than the speed of light, you can never conclude that you are going faster than the speed of light. (Unless you wanted to define everything in the universe as moving faster than the speed of light in the same direction, but that just makes the math stupid for no reason.) If you start accelerating, you will find that the amount of energy required to go faster (or, equivalently, to push other objects away from you faster) increases to infinity as you approach the speed of light.