Real Rules for Time Travelers Is a Handy Helper for Lost Theories

Illustration for article titled Real Rules for Time Travelers Is a Handy Helper for Lost Theories

Discover Magazine has a great article on the real science and logic of the paradoxes of time travel. Just what is possible and what isn't? Prepare to have your brain at least partially melted.

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Sure, it doesn't address anything pesky like parallel timelines, but it does talk about the impossibility of changing something that's already happened.

The nub of the problem is that you cannot have a consistent "arrow of time" in the presence of closed timelike curves. The arrow of time is simply the distinction between the past and the future. We can turn an egg into an omelet, but not an omelet into an egg; we remember yesterday, but not tomorrow; we are born, grow older, and die, never the reverse. Scientists explain all of these manifestations of the arrow of time in terms of entropy-loosely, the "disorderliness" of a system. A neatly stacked collection of papers has a low entropy, while the same collection scattered across a desktop has a high entropy. The entropy of any system left to its own devices will either increase with time or stay constant; that is the celebrated second law of thermodynamics. The arrow of time comes down to the fact that entropy increases toward the future and was lower in the past.

But what the hell is that temple all about, science?! [Discover]

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SandyEggo
SEDAGIVE?!

"We can turn an egg into an omelet, but not an omelet into an egg"

"A neatly stacked collection of papers has a low entropy, while the same collection scattered across a desktop has a high entropy. The entropy of any system left to its own devices will either increase with time or stay constant; that is the celebrated second law of thermodynamics."

Then we are presented with the problem of everything we see around us in the Universe. Shortly after the Big Bang (if that's what happened), there was the ultimate universal egg scramble scattered everywhere. Now we see the effects of billions of years of that "scrambled egg" of matter forming into "eggs" such as planets and solar systems. Then there's organisms, and actual eggs.

When we watch the universe around us, we see the second law of thermodynamics in action, and it makes sense. But then we look around us and see so much order that gets so much more complex as we get ever more microscopic in scope, and see a world which is fraught with order and complexity orders of magnitude greater than that of a relatively simple egg.

Either the second law of thermodynamics is wrong, or there is something else working expressly against it, and working very hard and doing a damn fine job of it.