Mike_Fontenot
Registered Senior Member
This is from the Opening Post/TOPIC of thread.
When an individual ponders his experiences, he can order the events in his life using the criteria of before and after. He can assign a number to each event in such a way that events assigned a lower number occurred before events assigned a higher number.
It's those numbers, but in addition it's the elapsed reading on the individual's watch (and calendar) between each of those numbers. That combined information is stored in our memories.
On a science level I do not think we could reverse time [...]
The traveler (he) in the twin "paradox" DOES reverse time for the home twin (her), according to HIM, when he accelerates in the direction AWAY from her (provided they are not co-located then). I.e., According to HIM, she gets rapidly YOUNGER when he accelerates in the direction away from her. (And the amount of that age change also depends linearly on the distance between the twins.) But that does NOT mean that ANY events in the past are altered in any way. The idea, that she could suddenly get younger, according to him, when he accelerates in the direction away from her, is abhorrent and even horrifying to many physicists (both amateur and professional). But her getting younger is mandated by the Minkowski diagram (which is itself mandated by the Lorentz equations). And my conclusion is shared by at least one professional physicist (and I suspect MORE than one): Brian Greene (well-known proponent of string theory) wrote a popular book called "The Fabric of the Cosmos", and PBS asked him a few years ago to do a NOVA TV show on that material. In that program (and in the book), he gives an example of an extremely distant intelligent alien who is riding back-and-forth on his bicycle. Every time he reverses direction, the current time on earth varies by about 400 years, forward and backward depending upon the direction of his velocity reversal. (The reason that such relativity effects can be produced even by non-relativistic speeds is that the distance is so enormous). Here is a 10-minute YouTube clip of that NOVA show, giving that example. I recommend immediately scanning forward to the 6:00 minute point, where the alien example starts. (It may also be necessary now to click "skip commercial" to get to the NOVA clip):