View Single Post
Old 01-22-2008, 10:11 PM   #63
still unsmited
Gnosital's Avatar
Join Date: Sep 2005
Posts: 4,661
a different tim wrote View Post
From what I recall a Boltzmann brain isn't one that evolved. The idea is that if you have a universe that lasts for more than a certian amount of time such a brain will spontaneously arise at some point because of quantum because sooner or later a bunch of atoms will fall into that configuration. Complete with sensory inputs and possibly a jar full of nutrients to keep it from instantly exploding in a vacuum.
I think my brain is floating now. 'Spontaneously arise', as in a bunch of particles could suddenly organize into a variety of molecules, and molecules into proteins and lipids, and those into sub-cellular organelles, and those into cells and those into functionally related nuclei, and those into cellular assemblies, and those into a sensing, perceiving brain? Obviously my perceptual set has been biased by my actual current universe.

Sure, the odds are pretty low, but then again given enough time anything can happen, and the assumption is that there is enough time.
Do YOU think that ANYTHING can happen? I'm failing to grasp this as a possibility. If that's the case, then there is a possibility of a universe with a goad allsmitey in it, and that's just not ok.

Now, the simpler universe thing, I think, arises because our kind of consciousness can only arise in a relatively low entropy universe because our kind of life depends on reasonably constant and predictable energy flows to evolve (in our case, sunlight), which means that there must be some fairly major thermodynamic imbalances to create them. But a Boltzmann brain could arise in a high entropy universe (one in which everything has evened out thermodynamically and that is basically just a low temperature gas) if you wait long enough. This kind of universe is simpler, and a universe that has reached a high entropy state has nowhere else to go. So we get a model of the universe in which we have a relatively short period (a few tens of billions of years) of stars, life etc, and a much longer period of low temperature gas and boltzmann brains.
I have to work on this part for a while.... I'm slow....and I have no concept whatsoever of what a high entropy universe means. I must look some stuff up.

The complication comes because we don't know if this high entropy state is stable. Lots of models of the universe don't end there - you can get proton decay getting rid of all the atoms, or a big rip caused by the expansion of space, or indeed a gravitational collapse and big crunch. So the question is, is this low entropy period finite, and if so, is it long enough for the Boltzmann brains to outnumber us?

If so, it is claimed we are not typical observers, and we are observing the universe in an atypical state, and we therefore can't draw any general conclusions from our observations, therefore science is fucked (although since our observations are systematic, well documented, and we take care that any general conclusions are testable or we don't let them into science I don't think this claim holds water). Some people also think that it would mean that we in some way "ought" to be Boltzmann brains, because that is more likely, and the observed fact that we aren't profound. And some people claim that the fact we aren't Boltzmann brains means that there must be an upper limit to the potential age of the universe, otherwise we would be.
*sigh* But science can't be fucked because its claims are only relevant to the atypical state in which we exist. If we can't generalize to what we can't observe, then that isn't necessarily a flaw in our observational techniques, which seems to me to be well-accounted for within the 2 scientific assumptions, innit? The freaky observer theory is just saying we can't generalize known physics to unknown universes?

A brief look at the above will reveal the tenuous chain of assumption, teleology with explosive diarrhea, half baked philosophy, dubious logic, and untestable hypothesis that it's all based on, so my advice is shrug and say wtf. This is what happens when physicists think that philosophy is trivial and try to embark on it without proper training.
But the article I posted seemed to imply that the mathz are now freakily in agreement with some of this Boltzman bidness, right? SO could that be a fluke? Or bad mathz?

PS, thanks for 'splainin this, ADT! These kinds of articles really piss me off because I can't judge how much is bullshit and how much is simply beyond my ken. My ken has very short arms, you know. And your ken seems way bigger than mine.
Gnosital is offline   Reply With Quote