Are the laws of physics invariant wrt time inversion?

Question

Events seen when movie is played bacwards look funny.
What laws of physics are possibly violated by inverson
of time?

Answer 1

Mostly the second law of thermodynamics - the entropy of a system must increase. So, if we see water spilling on the floor from a jug and forming a puddle, this is water going from an ordered to a less-ordered state. If we see the inverse, water droplets forming into a stream and leaping back into a jug, this looks weird to us - energy must have been applied to achieve that result. Also, dissipation of energy into entropy (e.g. when a bouncing ball comes to rest) is a similar phenomenon. Other than that, most of physics is perfectly invertible. But this one principle appears in many, many, many contexts.

Answer 2

As an atheist and scientist i'm conscious that technology is often open to advancements, unlike religions which at the instant can not advancements, and, for the main section, continues to be regretfully locked right into a anti-technology strategies-set. Aether Physics became a postulate or conjecture that did no longer proceed to exist for terribly long after it became proposed, as Micheleson and Morely have been waiting to tutor the fee of sunshine did no longer selection in line with which way the beam of sunshine became traveling in. it would have assorted if aether existed. considering the fact that aether physics had by no ability been shown or examined it became no longer technology and basically a conjecture or hypothesis and not a medical concept or regulation. So no regulation became violated. you're misrepresenting the reality, or a minimum of don't comprehend what technology is and how it somewhat works. as far as exactness is going you may recommend precision or accuracy. it is no longer clean what you recommend. i think of you meant invariant somewhat of suitable. yet once you meant precision, it is genuine that any medical length ought to additionally incorporate a level of precision or how close the measurements are to a minimum of one yet another in repeated runs of an test. this promises a manner of judging how good your experiments are to generating consistent outcomes. in case you meant accuracy, you're speaking approximately how close the attempt outcomes are to the genuine fee. it is a annoying problem to confirm what the predicted genuine fee is while all you have are your attempt outcomes to bypass via. that's the reason it is a sturdy thought to have a sort of experiements that produce measurements utilising diverse procedures. The length of the fee of sunshine is a sturdy occasion. And utilising the melting of chocolate in a microwave oven is a sturdy way for even severe college student to degree that utilising the formula of the fee of sunshine is comparable to the wave length x frequency. The precision and accuracy are especially on the brink of the examined fee utilising plenty extra state-of-the-artwork and high priced ability.

Answer 3

Not exactly. You must also take the mirror image and change everything into its antiparticle for the dynamical equations of physics to be the same. This is called CPT invariance. However, to know how things will actually behave, you need to know the boundary conditions of the problem too. Time asymmetry of these conditions on a cosmic scale results in behavior that is statistically time asymmetric, like movie example. No one knows why this asymmetry exists.

Answer 4

Almost the entirety of physics is described with differential-integral equations, which work perfectly either forward or backwards in time. That was one of the great puzzles regarding entropy, which was resolved via statistical mechanics. it's easy to generalize and say that "laws involving irreversible processes aren't invariant under time reversal", but the deeper question is whether or not physical reality is more accurately described by "evolution of states" (think cellular automata), which are only rarely time-reversible. It's possible that time-reversiblity is a form of symmetry we really can't take for granted, but given that it exists, it does allow for a great variety of interesting physical processes. For example, perhaps at sub-Planckian dimensions, differential-integral equations are inadequate to describe physical reality, and it's only at larger scales and in the statistically approximate sense, a measure of "time-reversibility" is afforded, and we're blessed with all the wonderful laws of physics that our ordinary reality have come to depend on.

Answer 5

Statistical thermodynamics, of course, varies under time-flip per the 2nd law. Noone has discovered time-flip variance in the underlying laws of physics directly, but we think it has to be there because it is a fundamental result of field theory that physics is invariant under Charge Conjugation * Parity Inversion * Time Flip (CPT). We have identified violation of CP, so we suspect that T must be violated as well.

Answer 6

When you talk about time inversion, you are talking about antimatter. We have only limitted observations of antiparticles in high-energy colliders, and no observations of anti-atoms and anti-molecules. So most "theories" about time reversal are just opinions made up to support some scientists religious beliefs.

According to my own Fractal Foam Model of Universes, yes, antimatter universes work exactly like "normal" matter universes, except on a vastly different scale. There is gravitational attraction in reverse time; so to us it looks like repulsion. The cosmic foam of our sub-universe expands relative to its own ether, causing its cosmic bubbles to pop. To us that looks like the bubbles are un-popping.

Answer 7

Angular momentum does not time-reverse (Feynman's sprinkler). Magnetic optical rotation and centripetal spin are time parity-odd. Given: a motion picture film can with one port pierced through its broad face center orthogonal to its surface and another port pierced tangential to its edge. Fill with water.

Pump water in the center and out the edge - no problem. Timer reverse to pump water in the edge and out the center - no flow; angular momentum is conserved. It's a fluid diode with no moving parts.

Entropy is a weak arrow of time - pushed in one direction by probability. Angular momentum is a strong arrow of time - pushed in one direction by vacuum isotropy and Noether's theorem thereupon.