Jake Young is a 
Dennis Overbye of the NYTimes had this to say of cosmologists who are speculating about disembodied brains spontaneously generated in empty space:
If you are inclined to skepticism this debate might seem like further evidence that cosmologists, who gave us dark matter, dark energy and speak with apparent aplomb about gazillions of parallel universes, have finally lost their minds. But the cosmologists say the brain problem serves as a valuable reality check as they contemplate the far, far future and zillions of bubble universes popping off from one another in an ever-increasing rush through eternity.
What follows is -- fortunately -- a very good discussion of why such a universe is absurd.
Cosmic Variance has the issue well-covered:
The point about Boltzmann's Brains is not that they are a fascinating prediction of an exciting new picture of the multiverse. On the contrary, the point is that they constitute a reductio ad absurdum that is meant to show the silliness of a certain kind of cosmology -- one in which the low-entropy universe we see is a statistical fluctuation around an equilibrium state of maximal entropy.
A good scientific principle: if your theory yields results that are patently ridiculous and in clear contradiction with the observable universe, the problem is with your theory, not with the universe.
Physical Science
Comments
A good scientific principle: if you theory yields results that are patently ridiculous...
I disagree with the way you wrote this. "patently rediculous" according to what standard? The creationists would say that us evolving from monkeys is "patently rediculous". And I'd say that quantum mechanics is too -- it is an affront to common sense.
So drop that first clause:
A good scientific principle: if your theory yields results that are in clear contradiction with the observable universe, the problem is with your theory, not with the universe.
Posted by: kevin | January 15, 2008 12:38 PM
Cosmological Last Thursdayism.
Posted by: Nicky | January 16, 2008 2:24 AM
A good scientific principle: if your theory yields results that are patently ridiculous and in clear contradiction with the observable universe, the problem is with your theory, not with the universe.
In a way I feel sorry for the cosmologists and the Quantum physicists! So much of there stuff sounds like the epitome of SCI Fi. But then again if you hang around a few decades a lot of their stuff ends up cutting edge!
Dave Briggs :~)
Posted by: Dave Briggs | January 16, 2008 4:21 PM
It occurs to me that you could do a genetic screen for interesting phenotypes in Boltzman Brains for your PhD thesis! There must be millions of these, some of these must be thinking really weird thoughts, and you won't need IRB approval from your institution.
Posted by: M Pol | January 17, 2008 4:16 PM