"Starts with a Bang" on the Boltzmann Brain Problem

A friend of mine referred me to this site during an email debate about philosophy of religion. I won't get into the details, but basically our argument was over whether someone could logically trust their senses if they believed that the universe arose in a random fluctuation. I had come across this site before but I didn't remember why I had decided it was wrong. I dug through some old emails I had started writing to Alvin Plantinga (before I decided he probably wouldn't read long emails), and came across this (if I may pretentiously quote myself):
"The evolutionary process has a finite amount of time in which to work (because of eventual heat death), while Boltzmann brains have an infinite amount of time to appear in any given universe (that doesn't recollapse), and in the environment that birthed those universes. The ordinary observers created by natural selection simply drop out of consideration, being overwhelmed by infinitely more Boltzmann Brains."
I wrote back to my friend with a paraphrase of this argument. However, for some reason I still think there was more to my objection, but I don't have enough time to figure that out right now.

Anyways, the guy who wrote the article I am objecting to is an astrophysicist; so given my lack of expertise in the area, I should tread lightly. However, Don N. Page observes something similar to my argument in one of his articles so there's possibility that I'm not insane: "Theories in which spacetime can last too long seem in danger of producing too many Boltzmann brains" (Observational Selection Effects in Quantum Cosmology)

And I certainly must disagree with what the post implies in this statement:
"Although there have been a number of scientific papers in the last couple of years on this topic, none of them were written, apparently, by anyone with a very deep understanding of biology."
Physicists certainly don't need to have a "deep" understanding of biology to know that evolution happened, and to understand entropy and thermodynamics better than biologists.

In fact, there may be reasons for not even considering evolution (in our estimation of the ratio between Boltzmann brains and ordinary observers) because there is no reason that evolution should produce a conscious organism. Evolution only selects for behavior, and not consciousness, and there is no way (that I am aware of) to pose a concrete relation between the two. This may sound a little nuts, but if you look at the Chinese Room argument (here at IEP) or (here at SEP) you may understand. This is especially true of a consciousness that would be aware of what is actually going on outside of itself, and not just the strange characters (if you will) that it is manipulating.

All we know (assuming our senses are trustworthy) is that we have evolved, and are conscious (I am rather, I don't know about you), and if materialism is correct then consciousness is a result material interactions that, given enough time, can be replicated by random fluctuations, and who knows what else. However, we can go further and say that because of the principle of mediocrity we can't even say that our consciousness is the most likely form, or that other material interactions can't produce similar effects.

We can't say for sure that a radioactive rock hasn't had a conscious thought at some point in its life/half-life. How would it tell us if it did? Have we every been able to put ourselves in the "shoes" of a whirlpool or a dust storm? Is the mud possibly more likely to be a conscious observer than the plants or worms it turns into? or even us? These are questions that cannot be answered from a materialistic perspective. Evolution may concentrate what we subjectively label as "complexity" but it doesn't guarantee that this form of complexity is more likely to result in consciousness.


Barnaby Dawson said...

There is no uniform probability distribution of the whole real line. Any distribution you use must give greater weight to earlier brains than later ones (in the limit). So there may be infinitely many Boltzman brains and yet your probability of being one of them could still be negligible.

Also can I recommend you read my post on why the heat death isn't so obvious:


Dwielz Camauf Descartes said...


Read your post, as well as some others of yours. You have a fascinating blog!

Now I don't spend a whole lot of time on physics (I'm a software engineer, and I have several hobbies), but I don't see why we can just assume that our universe was early in arising from its high entropy environment. We don't assume that everything has an end, so I don't see how we can use different reasoning when looking back and say there was a beginning to the multiverse or say that there is a finite amount of "time"(or whatever dimension/dimensions?) before the beginning of our universe.

But even regardless of that, let us say we can assume that our universe is early. What then follows? How do I know that I am not one the infinitely many future Boltzmann brains? To say that my observations reflect reality, and that I am actually in the early universe I observe begs the question as to whether or not I am a Boltzmann brain.

As for your argument relating to the 2nd law, I think you have some great points. I do have some comments/disagreements that I'll be sure to post later. (I do realize that my previous arguments are useless if your views on the 2nd law are correct) Thanks for your comment, I can see you have spent a lot of time on physics, pleasure to get feedback from you.