Big Picture Science – As You Were: Sean Carroll

by Gary Niederhoff on September 22, 2014

As You Were – Sean Carroll
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Part 4 of As You Were, featuring Sean Carroll, theoretical physicist at the California Institute of Technology, author of The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World, addressing the issue of why time runs in one direction.
(TRT 8:38)

{ 3 comments… read them below or add one }

avatar Richard Blakely September 26, 2014 at 9:45 pm

Comment on part 4: We can solve “the issue of why time runs in one direction” easily if we realize that to go back in time we need to also move back to where the Earth was. That motion is impossible because the Earth is moving very fast in space, and the Earth will never be where it was before.

avatar Gregory Slater October 11, 2014 at 9:28 am

Carroll actually gets paid ‘big bugs’ to do this? I’m shocked.

avatar Gregory Slater October 12, 2014 at 8:13 pm

The discussion at 05:14 – 06:34 makes no sense at all – clearly even to Seth. Here it is, and I challenge anyone to assert that Carroll’s explanation here is in anyway illuminating:

Seth [speculating]: …Could there be some part of the universe where going backwards in time would be an everyday thing?

Carroll: Well, yes and no, is the short answer. We can certainly come up with cosmological scenarios of like a very, very big universe, much bigger than what we actually observe, but it could be out there and not just seen by us, where in some parts of this universe the arrow of time points in the other direction. So, from our point of view, in those regions, entropy would be higher in the past and lower in the future. But, the point is that, what we call the past and future is defined by entropy, so the people who lived in those regions would say that the entropy was lower in the past and higher in the future, and they would think that we were going backwards – so nobody would be turning their scrambled eggs back into uncooked eggs. They would always remember the direction of time in which entropy was lower.

Seth [objecting, weakly]: Gee that, that doesn’t sound very satisfying somehow. Well..

Carroll [irritated]: You should be satisfied. It means that everyone sees the arrow of time point in the sensible direction.

Seth [resignedly, throwing in the towel]: I see, well, ok, well maybe I am satisfied… I mean…


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