Sunday, February 07, 2010

JUST IN: There is no such thing as Time Reversal!

Nobel Prize winner Anthony James Leggett has thrown a monkey wrench into one of Science Fiction's favorite hobby horse - manipulation of the time line.

In a recent lecture "Why Can't Time Run Backwards?," Leggett stated:
  • Reversing the time or speeding it up is not possible... The universe is hot and compact, so it is slowly in the process of cooling down. Time, therefore, is unidirectional.
because entropy only occurs in one direction - time can be thought of as moving one way and not another, but only in that direction.

In truth Leggett's comments really do not rule out classical time travel, where someone goes forward and back in time but they do negate time itself running backwards (kinda ruins the whole idea of "The Time Traveler's Wife" huh?)

There is more to be said in the IO9 article....check it out here

14 comments:

Ron Huber said...

Wait...In the Once and Future King, Merlin the Magician lives his entire life backwards.

So there!

Beam Me Up said...

it would appear that Merlin was mistaken

Ron Huber said...

Professor L said "The universe is hot and compact, so it is slowly in the process of cooling down. Time, therefore, is unidirectional."

Well, sure, THIS universe is cooling down. But a single tree is not the whole forest, eh?

Beam Me Up said...

it is if you can only climb one tree

Ron Huber said...

I mean there's new universes born all the time, right? and during their gestation they're pumping up their temperatures as they heat and compact, right? So time _could be_ multidirectional in them, right?

So you just hook a quantum turnbuckle onto a chorionic infundibulator, chuck the whole mess into a nearby neo-universe, as we call the young'uns, (with YOUR end firmly affixed with the finest of zinc paste to your cranium), and let 'er rip! Wooooohoooo! You're trading wopjokes with Boccaccio, He of course, is putting down your time traveler's naivete in rich detail in return.

...till the paste dries and you flicker back to "here", with everything smelling and tasting of zinc.

Beam Me Up said...

Ron
I think people make a bad mistake when they only view entropy from the last 50% of the process. A bomb is entropic from the microsecond you push the plunger though to the observer things are heating up and pressure is building, but the backside of that process is the available fuel is being used to support the process therefor the energy equation is not balanced but fully negative. The same rules apply for a fire cracker to a pocket universe - no free rides and no free lunches

Ron Huber said...

When.....
"you push the plunger"
That push is not an act of entropy, is it?

Beam Me Up said...

I would say that any action that takes the energy level from a high to a lower state are entropic so quite possibly the thought of pushing the button or even realizing that there is a button is entropic.

Ron Huber said...

Dang! But action is not in itself entropic; the void left after, that the universe rushes to fill post-action, that RE-action IS.

Beam Me Up said...

Ron
Think about it....First off, action is a change in state. By the second rule of thermo-dynamics we understand that energy can not be made or destroyed just transformed. if we agree that entropic law states that all energy must go from a higher more organized state to a lower less organized state then we also have to agree that by performing an action and thereby using energy then we have transformed that energy to a lower state and there for the action by its very nature is entropic.

Anonymous said...

What nonsense! This is like saying that since the earth is rotating from west to east you can not travel from New York to California.

Beam Me Up said...

Since when does traveling in Newtonian space reflect wether or not time can flow backwards. Remember the article doesn't say you cant travel the time stream, but it only goes in one direction. Your example Anon doesnt deal with time at all. When you travel east to west north to south or west to east it is in the same time frame, past to future. Plus in each example, they are ALWAYS entropic! So you make the argument, not disprove it.

Anonymous said...

Let me explain. The total global entropy is increasing in this universe, hence global time for the universe as a whole goes from past to future. This does not negate the fact that for a small local area entropy can decrease (water turns to ice). Therefore on a local area time can go from past to future or future to past without changing the global time.

Now the reference to earth. The earth's global motion is from west to east but one can still have a local motion from east to west without changing the motion of the globe.

Beam Me Up said...

Anon
Interesting....you almost came out and said that time theory may be based on a chaotic model... If that is so then I would think then that we would still have to ascribe to a Mandelbrot frame work...but the water just got deeper than I expected...got me thinking.

ok still got to pull one one string here though. You said "one can still have a local motion from east to west without changing the motion of the globe" umm, you KNOW that's not true...come on! lol It may be infentesimal, but the effect is always there and it is always entropic! Even the Earth orbiting the Sun slows the Sun's rotation. NASA's gravity tractor is based on the effect. I am willing to give that time may be chaotic, but be it ever so small, travel from east to west will and does effect the Earth's motion...I know...being a bit flip and fast and free with the actual effect...couldn't let it go. Though there is some very odd math when we start going there, some I have a real hard time wrapping my heard around. But as long as we just talk about net effects, I don't think I will start bleeding from the ears...