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I was wondering if it is actually possible to distinguish if something is in motion, or at rest without simply stating that it is, or it is not? The statement that there is no such thing as something being at rest; I have read before, so the ball sitting on the table from one perspective is at rest, from another; it is not. If the ball were rolling across the table at any point it could be said to be at rest. The thing that seemed interesting to me is that there does not seem to be anything physically different about the ball whether it is perceived to be at rest, or if it is perceived to be moving because the ball is always in balance with the forces acting on it.

If there is no acceleration, then there is no measurement you can do which will determine what is moving or what is at rest. Which is why motion is always referenced to something else — a ball is moving with respect to a table, for example, or on could also say the table is moving with respect to the ball. There is no difference in the physics for either case. The upshot to all of that is that there is no such thing as absolute motion.

If there is an acceleration, all bets are off. Acceleration can be unambiguously determined.

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There is the mass gain as the ball moves to consider. Does E=MC2 account for this gain in mass? Maybe I need to think about this question a little bit more?

Yes. I think that's what Einstein says.

If the ball can not be accelerated to C because it has mass. It would seem that once the ball has been accelerated to is maximum, that the formula says that at this point there should be a measurable difference between the balls maximum acceleration energy and its total potential energy. Maximum acceleration energy would seem to mean maximum mass potential for the ball, and the measurable difference would have to be mass-less energy. This is actually a question and not a statement.

From our perspective, when we accelerate something it gains mass as per E=MC2. The increase in mass is exponential as per C2. And I think we all know what happens in a graph of y=x2! Such a speed is never reached.

Not forgetting time dilation. As far as the accelerated object is concerned, things around not so accelerated will presumably speed up in time. How does this fit with the laws of physics for example? Like, if you or I were on a rocket ship so accelerated, and looked back on the Earth apparently orbiting the Sun much faster, why doesn't it then fly off into space? It doesn't fly off into space because it, and everything associated with it, get or appear smaller so keeping things in order with the laws of physics that we know and love.

To summarise: We accelerate something and it gets bigger as per E=MC2. If you or I were on or travelled with that something, we wouldn't feel any bigger, but we would see everything else not so accelerated get smaller!

I think someone once said: everything is an illusion.

The universe is undoubtedly a strange place - certainly strange to us mere mortals whose brain has evolved to simply deal with survival on this good earth.

Edited by Delbert

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