The Stand-Up Physicist: Time Reversal and Spin

[ajhrockerboy6]

perhaps death is the entrance to a time-symmetrical universe in which a person is born old and dies a baby. i know it sounds like sci-fi and bizarre concepts but if you truly think about the origin of the universe this could theoretically happen.

[pandpinjapan]

You are the man!

[LANN98]

please email me your equations. i can barely see this choppy video.

[LANN98]

please email me your equations. i can barely see your video because it is so choppy.

[356Spunky]

Thanks for your videos Doug. I've been finding them really helpful in trying to understand some of the more elusive concepts of QM.  They're great for creating a visual image of the events in question.

[sweetser]

That was the goal. Do note that my work has not been embraced by anyone with a proper education :-) If you do go for a more formal education, these pictures may give you a technical edge.

[shanelejts]

thank you for taking time out of your life to help explain time reversal =D.

[WisdomVendor]

when you speak of a "local" transform, are you referring to a situation similar to a "closed system"?

[sweetser]

By local, I mean the transformation depends on the values of t, x, y, and z. The Lorentz transformations are global and only depend on the velocity, not on location. In standard physics, time reversal is a global transformation, using the member of the Lorentz group that has on the diagonal {-1, 1, 1, 1}. The -1 flips time's sign wherever. For low velocity, my approach mimics this to a high degree. Yet the mimic is not perfect, which was the point I tried to make.

[koolyoh213]

in electronic eng. maxwell's 1st equation is invariant to time reverse i think?

so what does this mean to me? im gonna find out.

ok proceed with the lecture, this is very interesting.

[dougsweetser]

Hello:

Nearly all laws in physics are invariant under time reversal. The exception is the second law of thermodynamics. People who study this sort of thing think that the asymmetry is "put in by hand." With quaternions, there is a reason for the asymmetry.

[warlock1276]

nice.. interesting