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A mind experiment about speed and time

  1. Oct 8, 2011 #1
    According to Einstein's theory, the fastest speed in this world is the speed of light. lets break this role for a sec.

    so here is the experiment:
    imagine a sphere moves infinitely quick relative to us. as quick as if its omnipresent, it seems appearing at every position at each time.
    now, this sphere is doing a rotation. its rotating around and its follows an orbit. when we touch it, no mater where we touch we can touch the sphere, which means to us, it is actually still! It becomes a donut-shaped still object to us, the observer.
    now let us walk around this still object . the question is, how fast we walk relative to the donut to recognize it is actually a moving sphere?

  2. jcsd
  3. Oct 11, 2011 #2
    I can see what you're saying here. But, think of it this way. You can go at superluminal speeds if you have a negative net force of gravity acting on you, which'd mean that the space-time continuum is curved upward instead of downward. But this would almost certainly mean that the object should have a negative mass. Though, this could be argued. But how could an object have a negative mass? I have no clue, unless it does. It's like the beginning of the universe, it just happened. Well, at least that's how I understand it. We know for a fact that we don't know everything about the universe yet. M-Theory is like a puzzle. The edges are easy to find, but it's hard to work from the inside out. There's just a gap between the inside and the edges that makes it so we can't, as of yet, finish the puzzle. So, let's see what happens when we put negative masses, energy, and gravity into that gap...
  4. Oct 15, 2011 #3
    If the sphere is traveling infinitely fast relative to us then we will never be able to see the sphere as a sphere because we will never be able to travel as fast as the sphere. Atleast this is my thought on it, good thought expirement though! :)
  5. Oct 17, 2011 #4
    We already have something similar. We call it HUP, now you might point out that as we can choose a observable, neither of those properties are 'really' impossible to define, but in a measurement one of them will be. And although it doesn't speak about a 'speed' it still becomes impossible to define, which I like even better than the idea of 'motion' :)

    It's quite foggy down there.
  6. Oct 17, 2011 #5
    This has nothing to do with Einstein's theory. You don't need to go faster than light in order to give an impression of a continuum. For example, a standard rate for movies is 16 frames per second, which is very, very slow in comparison with the speed of light, and yet it's good enough to fool us into seeing a continuum instead of a series of 16 still frames. Based on this, I'd guess that you can make your sphere move at this speed (or about) and it should give you an impression that it is a donut.

    So, to answer your question, how fast we have to walk to recognize that it is a sphere, take the speed of your sphere (it can be anything = S > F) and compare it to the speed necessary to fool us (that's the key = F), which, based on movie speed I'd guess at 16m/s, and get the difference: x = S - F = S - 16m/s
  7. Oct 21, 2011 #6
    You'd have to change pretty much all the laws of physics to answer this question... we cannot be made of atoms with particles and have strong, weak, electromagnetic and gravitational force. So in this imaginary universe, what are your alternatives? Is matter basically continuous with no empty space? What are the forces in this imaginary universe?
  8. Oct 21, 2011 #7
    It’s hard to imagine since it’s impossible. But OK. Wouldn’t it generate a huge electromagnetic field disturbance that would heat up everything around it to the point of exploding? Besides, I don’t think you’d be able to touch it. Instead, I think your finger would disappear. It would also generate an infinite amount of centrifugal force. So those are 3 clues that it’s not a donut. I don’t think you can ever tell it’s a sphere.
  9. Oct 21, 2011 #8
    I would think that you would have to move infinitely fast around it before you could notice it's infinite velocity, to answer the question. Any other speed would just be infinitely slower than the sphere, leaving it unoticed.
  10. Oct 21, 2011 #9
    Just to set things straight, standard frame rate for movies is 24 fps, not 16. And how did you come up with 16 m/s? It is even more nonsensical than OP's question.
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