Reverse Universe: Acceleration and Time Reversibility

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SUMMARY

The discussion centers on the concept of time reversibility in physics, particularly in a hypothetical 'Reverse Universe'. It establishes that acceleration, defined as the change in velocity over time, remains consistent in magnitude when comparing a real universe to its reverse counterpart. Specifically, if velocity changes from A to B in the real universe, the reverse universe experiences a change from -B to -A, resulting in the same acceleration value. The conversation also touches on the implications of the second law of thermodynamics regarding entropy.

PREREQUISITES
  • Understanding of basic physics concepts, including acceleration and velocity.
  • Familiarity with the second law of thermodynamics and entropy.
  • Knowledge of vector mathematics as it applies to motion.
  • Concept of time reversibility in physical laws.
NEXT STEPS
  • Explore the implications of time reversibility in classical mechanics.
  • Study the second law of thermodynamics and its exceptions in detail.
  • Investigate vector calculus as it relates to motion and acceleration.
  • Examine theoretical physics concepts surrounding hypothetical universes.
USEFUL FOR

This discussion is beneficial for physicists, students of physics, and anyone interested in the theoretical implications of time and motion in both real and hypothetical scenarios.

Vincit
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Among the physical laws it is a general characteristic that there is reversibility in time; that is, should the whole universe trace back the various positions that bodies in it have passed through in a given interval of time, but in the reverse order to that in which these positions actually occurred, then the universe, in this imaginary case, would still obey the same laws.

To test this supposed reversibility, we may imagine what we call 'Reverse Universe'. So, for example, if we had an imaginary universe, that universe would experience the same position of all bodies at various moments of time the same as the real universe; in reverse order.

But what would happen to a problem such as acceleration? I know that acceleration is the change of velocity divided by the interval of time required to produce this difference. So, if velocity A changed to velocity B, the equation(vectorially) would be B-A/T. So, in the corresponding motion of the reverse universe, wouldn't the velocity change from -B to -A, so that the acceleration is [(-A)-(-B)]/T. This is equal to B-A/T. Does that show that the magnitude of the acceleration will be the same in the reverse universe and the existing universe, but just reverse in order?

:/ I am being sidetracked by slight nuisances; help would be appreciated.
 
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Most laws are like that except the second law of thermodynamics, part of which states that for spontaneous (read: possible) events will cause a net increase in entropy in the universe.

The maths from your acceleration scenario isn't too surprising. If we take some numbers, say A = 2m/s, B = 10 m/s and T = 4s, we get an accelleration of 2m/s^2. Now going from -10m/s to -2m/s is still an increase in speed of 8m/s in 4s, giving the same accelleration.
One is an increase in speed in the positive direction and the other is a decrease in speed in the negative direction, which is the same accelleration.
 
I have a question, why the reverse U's velocity changes form -A to -B while the real U changes from B to B? Shouldn't it be from -B to -A ?
 

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