4 ms·
So does this mean speed faster than light is possible?
by rokalakt1337 7y ago
So does this mean speed faster than light is possible?
- zaarn 7y agoTwo objects can move away from eachother faster than the speed of light as seen by a third observer. The space between objects can also expand faster than light, the object itself can still not move faster than light. If the space between two objects is expanding faster than light then for all intents and purposes, the other objects no longer exists to another. There is no way to contact or observe that object other than the light that was send your way before space went FTL.
- eru 7y agoTo give another example: If you have a laser pointer and flick your wrist fast enough, the spot on the ground that your cat chases can move faster than light without violating any laws of physics. That's perhaps easier to see, if you think of a giant laserpointer aimed at the moon. Similarly, a shadow on the wall can move faster than the speed of light.
- Aenyn 7y agoWouldn't there be a delay between the time you flicked your wrist and the time the spot actually aligns, due to the limited speed of light?
- doliveira 7y agoYeah, and observing this is a good way to see that information isn't actually being transferred faster than light.
- eru 7y agoYep, definitely. An outside observer that just sees the spot on the moon (but has no clue that it's produced by you flicking your wrists), just sees a spot that moves insanely fast. No information, energy nor matter travels faster than light here, of course.
- rokalakt1337 7y agoGotcha, so it appears to be moving faster, but relative to its point of reference it is not. I am wondering tho, what laws of physics state that there just is _no way_ of moving faster than light? Apologies for the lack of knowledge, I genuinely don't understand / know where this limitation is coming from.
- zaarn 7y agoI'm not sure if there is any single law that states nothing moves faster than the speed of light. Quantum mechanics limit the spread of information to the speed of light, most wave functions including the fundamental forces propagate at the speed of light and acceleration requires increasing amounts of energy the close your come to the speed of light. I guess one way to look at where this comes from is to look at Conway's Game of Life. A cell in this game spawns if enough neighbors are present and with some trickery you can make things that move. But due to the rules of the game, nothing moves faster than 1 square per round. There is no explicit rule that the speed of light in that game is 1 square per round, it's just that the way the rules work, the fastest thing could only possibly be that fast. Everything is limited to this speed that doesn't exist in the game. If you changed the rules to allow cells to die or spawn depending on cells up to 1 square inbetween in distance, the speed of light would be 2 squares and none of the rules will explicitly state this limit.
- pure-awesome 7y agoThe proper formulation of the light-speed restriction is that no information can travel between two points in space faster than light-speed. The expansion of space itself doesn't violate that - you couldn't use it to communicate with someone in an FTL way.
- mFixman 7y agoThe comparison that helped me understand it was seeing the Universe as a balloon. My friend and I both live at different points on the surface of a balloon with distance A. I throw a ball at light speed while the balloon is being inflated, and the distance between us is B when the ball reaches him after T time. To my friend it seems that the ball was thrown at B / T speed, which is faster than the speed of light.
- namirez 7y agoYou cannot travel faster than light in spacetime but spacetime metric can expand faster than light. There is no speed limit on the evolution of spacetime itself as far as we know.