Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: yamo on 25/05/2011 07:15:12
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If time slows near the speed of light, is there a way to speed time up?
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Sure, just speed away as fast as possible, then watch how the universe accelerate away its time relative you. But if you by that mean if there is some way for you personally to either stop aging, or for that sake age any faster.
No.
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A time dilation is always relative something. When the twin has returned to Earth his 'time dilation' is relative his twin, and if you like, maybe some other parts of the universe. It all depends. You can assume that at any moment we have 'stuff' accelerating away relative us begetting a 'time dilation' by doing so. That 'time dilation' will be relative the rest of the universe. But you can also make an assumption that some of those 'accelerating' might have the exact same 'speed' if measured by earth. Then those accelerations should be in the same 'frame of reference' relative each other and so experience no time dilation. (assuming the exact same type of 'stuff' in a exact same overall 'gravity' here.)
But in reality I would expect each point in space to have a different gravitational value, that is if we assume that gravity will weaken with distance. And so it will become very tricky to define any two objects as having the exact same 'frame of reference'. It's most probably infinitely improbable to do so, but if the universe is 'infinite'?
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What if i speed the entire universe up to near c but i stand still?
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Moving clocks always appear to be running slow when you check them against your clock. This would still be the case if you accelerated the rest of the universe. They would see you as moving and would think your clock was running slow.
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That one was nice, but 'tricky' to think about. We can, as JP did, define it as a equivalence where you can exchange one frame for the other. We can also assume that you meant truly 'accelerating'. The problem here is that you define it as the whole universe. If we do that then we have no frame to compare that acceleration too, except the one being 'still' (you) relative it. In a acceleration you will always know that something is happening locally, except when accelerating at a constant speed, for example one gravity, (earth) where you in a black box won't be able to decide if you're still on earth, or accelerating in space with your spacecraft (ignoring tidal forces).
Assuming that it is not a uniform constant acceleration the universe at large will know who it is 'changing' (still in a 'black box' and if the whole of the universe was doing so, it definitely becomes one:). Assuming a constant 'acceleration' the universe would find itself unable to define any 'motion' in a positional system as I think of it.
But what would it see looking at you :)
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In fact it becomes extremely tricky, for example what about the tangents as everything orbits and spins, will the angular 'motions' take themselves out, or not, over a whole universe? In any uniformly moving frame, inertial in that it's described as being 'at rest' relative gravity, leaving you weightless in a 'geodesic', you will find yourself unable to observe any 'blue shift' internally.
But that none can find a 'blue shift' internally in its own frame of reference doesn't state that different uniform motions won't find a blue/red shift relative each other when measuring, and so also be able to define a speed, especially when considering that both of them measuring will find themselves to represent the 'true' inertial observer, (distant stars etc ignored) as they both follow a geodesic, well, as I see it.