Tuesday, January 15, 2008

Boltzmann's Brain

There is a new article by Dennis Overbye in the New York Times called, Big Brain Theory: Have Cosmologists Lost Theirs?

It could be the weirdest and most embarrassing prediction in the history of cosmology, if not science.

If true, it would mean that you yourself reading this article are more likely to be some momentary fluctuation in a field of matter and energy out in space than a person with a real past born through billions of years of evolution in an orderly star-spangled cosmos. Your memories and the world you think you see around you are illusions.

Source: Sean Carroll, California Institute of Technology

Alway part of the process is to find within my own site information that I had collected to help me understand where Ludwig Boltzmann comes into the picture in the above article.

Now of course I go over to Cosmic Variance's version of Boltzmann's Universe where the article above is referred too.

I look at the discussion that is taking place and try and put the exchange and points raised in mind so that I can understand as best I can "the jest" of the problem and the jest of what people are saying.

This isn't an attempt to rewrite the article, but to open the door to a better understanding of what is being portrayed.

Sean:lylebot, this is basically the point of the post — if the universe is a fluctuation around thermal equilibrium, then no matter what you condition on concerning our present state (including literally everything we know about it), it is overwhelmingly likely that it is a random fluctuation from a higher-entropy past. Even if we have memories apparently to the contrary!

The Universe and Irreversibility

Now it is quite loosely put together in my head that I went searching to try and understand the context in which the universe was placed in accordance to the state of equilibrium.

In equilibrium, the entropy of the system cannot increase (because it is already at a maximum) and it cannot decrease (because that would violate the second law of thermodynamics). The only changes allowed are those in which the entropy remains constant.

See: What is the entropy of the universe?

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