Thanks for the comment M Everett, regarding Occam's Razor and Boltzmann Brains I'd like to point you to some comments about this by David Chalmers as well as Brian Greene, a great defender of physicalism. Both comment the concept of Boltzmann brains completely undermines the whole enterprise of science. Science is built on empirical evidence, rational thought, experiementation, etc., All of which would be mere appearances in brief moments in the random accumulation of particles that constitute such a brain. Anything that appears in this structure is completely temporary, random and provides only an illusion of rationality. Our scientific knowledge would be merely an illusion.
Physicist Tim Andersen does a good job of explaining why Boltzmann Brains make rationality and knowlege meaningless:
