It's official: Time machines won't work

http://latimesblogs.latimes.com/technology/2011/07/time-travel-impossible.html

by uladzislau • 15 years ago

11 7 15 years ago

latimesblogs.latimes.com

__rkaup__• 15 years ago

I've always wondered: isn't travelling to the past the same thing as making matter from nothing? That is, since then there would be two copies of you.

Udo• 15 years ago

Kind of, I always saw it as leaving this universe irreversibly and entering an earlier version of it from out of nowhere. But since atoms don't have unique IDs, it's no problem to have two (almost) identical people beside each other.

Also, contrary to popular fiction, the past isn't changed only because a blundering human is transported into it, it is already altered by the mere introduction of additional matter into a system that would have evolved differently without it. So, if you want to change the past, transport a single proton back 2 million years into some swamp. Of course, that would be pointless because nobody would ever know what changed...

The real conundrum is what actually happens to the "old" universe at the instant of traveling back into the past. Is everything that happened between those two points in time erased? Or does the old universe continue as if nothing happened and a new parallel one branches out that is of no consequence at all? In the infinite universes theory, time travel would merely amount to "jumping" into the "right" neighboring universe (however, personally this whole business with infinite branching parallel universes always seemed like a wasteful and inelegant model to me).

All these theories have one thing in common though: things change only for the time travelers themselves. So for meaningful time travel, you would have to be able to transport whole beings across a doorway in spacetime. Twice. In the right direction. Given the known conditions near theoretically surmised holes in spacetime, that's not an easy task. Atoms: maybe. Huge fragile collections of unstable molecules: probably not.

glimcat2• 15 years ago

Well, does the past currently exist?

glimcat2• 15 years ago

There was some real science done. Then the media took it and ran with it.

Spoilers: the real science did not in any way involve time travel.

hamner• 15 years ago

Please link to more reputable sources for scientific articles. For an example, the university press release is intended for a general audience and more factual: http://www.ust.hk/eng/news/press_20110719-893.html, and the peer-reviewed publication is here: http://www.phys.ust.hk/dusw/Publication/PhysRevLett_106_2436...

nohat• 15 years ago

The research determined that single photons could not move faster than the speed of light (sounds obvious, but quantum scale objects don't necessarily behave). This does not disprove time travel, just one hypothetical phenomena that could have led to time travel.

beej71• 15 years ago

Dup and ancient. I read this back in 2067.

It's official: Time machines won't work

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