Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: yor_on on 29/12/2012 09:21:10
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"The important conceptual difference in relativity however is that inertia, defined as the resistance to motion, depends on the velocity of the particle so that the higher the velocity, the harder it is to accelerate it." from What's the difference between the five masses: (http://physics.stackexchange.com/questions/8610/whats-the-difference-between-the-five-masses-inertial-mass-gravitational-mass)
On the other hand, in any uniformly moving body you won't be able to locally measure any change of 'energy' belonging to that body as far as I know. doesn't matter if you, continuously existing 'at rest' with it, together have been accelerated to then move uniformly again. The energy is always relative another frame of reference, not locally perceivable?
And then we have the statement that all uniform motion are the same, relatively and locally exchangeable with being at rest, leaving you free to define your motion as non existent.
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How does it work? Assume that you accelerate a proper mass (earth) in steps, and find that it cost you more energy each time you do so. Then relative what?
And how does it fit the idea of all uniform motions being the same?
You could assume that if there is no such thing as a definable energy differences locally (at rest with what you measure) when measuring different uniform motions locally, then it shouldn't matter, but it does. And, doesn't it state that relative motion isn't relative at all?
The universe must have a speedometer :)
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Or maybe it doesn't. :)
You could also assume that what we see as inertial mass (resistance to being 'moved') being a equilibrium that you can change accelerating, costing you energy. And then the question becomes: Where would it cost that energy? At what scale? If it was microscopical changes in the mass shouldn't that be measurable? But if it was so, I might assume that the 'speedometer' is non existent, only equilibrium or accelerations existing.
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And it all seem to go back to me wondering what makes it possible? Symmetry breaks? Assume one 'energy' to a universe, then explain how it come to differ in 'useful energy', able to be transformed, relative 'un-useful energy' like that heat we expect to ultimately become diffused/dispersed throughout the universe?
Where and what make the transformations possible? Do we have some theorem describing such a thing? Why would a (assumed) equilibrium break down into 'opposites' and 'useful' relative 'not useful' energy with a entropic and timely arrow?
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I think everything is indicating that there should be a universal "speed limit" in space of c, or about 299,792 km/s vs some unknown "fabric of space".
And, if we are moving in space, then it might be different in each direction. The problem is that one might not ever be able to detect the difference.
Your acceleration theory might be good. But, it still may be beyond what we may be able to detect.
For example, in a circular particle accelerator, we would be unable to detect different speeds of a particle on a +X vs a -X leg.
Perhaps if one took a linear particle accelerator (hopefully on an E/W orientation). Then, with a constant energy input, one should get a uniform final velocity and traversal time. Conduct the experiment either 6 hours, or 6 months later, and one can get different directions of Earth's motion in space and orientations of the accelerator in space.
I'm still not convinced that one could detect the difference with timing problems and other issues with relativity, but perhaps it is easier to detect differences in acceleration vs differences in velocity.
Is it possible that the "fabric of space" at the surface of the Earth would be spinning at the same velocity as Earth, somewhat like a ball spinning in syrup, thus making such a determination more difficult?
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These sorts of questions were asked by scientists decades ago, attempting to fathom the nature of electromagnetism and light. The final conclusion was: we need to completely rethink the concept of space and time, and the definition of motion. Space and time were merged into one continuum controlled by an unusual version of the Pythagorean Theorem that measures the absolute distances between events (rather than between objects as we normally think of distance). In it, objects in different states of motion became pathways laying at different angles. An observer would be laying in one of them, defined by his state of motion. Objects whose pathways were parallel to his would appear to him to be at rest. Physical quantities such as energy would be measured with respect to his state. Other observers, whose pathways lay at different angles, would view things differently, arriving at different values for many quantities. Because these quantities are reference-frame-dependent, they cannot usually be transferred from one observer to another, because that would involve changing their reference frame, which would introduce additional features into the problem so that overall no advantage is gained. For a more complete explanation, see
http://en.wikipedia.org/wiki/Special_relativity_for_beginners
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I might add that the question of energy becoming unavailable due to thermodynamic dissipation is an entirely different subject.
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And concerning changes of mass with speed: This change is entirely observer-dependent. It is seen by an observer that the object is moving with respect to, but is not seen by an observer that is moving along with the object. Likewise, an observer moving along with the object will perceive another object left behind with the first observer as having a greater mass that it does there.
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I edited the page with the error so it now reads "inertial mass is the mass measured by its resistance to changes in motion". There is no inherent resistance to motion because there is no preferred/special frame of reference in the universe.