Polemics

What are Boltzmann brains, and what challenge do they post to the multiverse hypothesis?

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I thought I would turn to the atheist theoretical physicist Sean Carroll, who has previously debated William Lane Craig, to explain to us what a Boltzmann brain is, and what threat it posts to the multiverse hypothesis.

Here is Sean Caroll, quoted by About.com:

Ludwig Boltzmann was one of the founders of the field of thermodynamics in the nineteenth century. One of the key concepts was the second law of thermodynamics, which says that the entropy of a closed system always increases. Since the universe is a closed system, we would expect the entropy to decrease over time. This means that, given enough time, the most likely state of the universe is one where everything is the in thermodynamic equilibrium … but we clearly don’t exist in a universe of this type since, after all, there is order all around us in various forms, not the least of which is the fact that we exist.

With this in mind, we can apply the anthropic principle to inform our reasoning by taking into account that we do, in fact, exist. Here the logic gets a little confusing, so I’m going to borrow the words from a couple of more detailed looks at the situation. As described by cosmologist Sean Carroll in From Eternity to Here:

Boltzmann invoked the anthropic principle (although he didn’t call it that) to explain why we wouldn’t find ourselves in one of the very common equilibrium phases: In equilibrium, life cannot exist. Clearly, what we want to do is find the most common conditions within such a universe that are hospitable to life. Or, if we want to be more careful, perhaps we should look for conditions that are not only hospitable to life, but hospitable to the particular kind of intelligent and self-aware life that we like to think we are….

We can take this logic to its ultimate conclusion. If what we want is a single planet, we certainly don’t need a hundred billion galaxies with a hundred billion stars each. And if what we want is a single person, we certainly don’t need an entire planet. But if in fact what we want is a single intelligence, able to think about the world, we don’t even need an entire person–we just need his or her brain.

So the reductio ad absurdum of this scenario is that the overwhelming majority of intelligences in this multiverse will be lonely, disembodied brains, who fluctuate gradually out of the surrounding chaos and then gradually dissolve back into it. Such sad creatures have been dubbed “Boltzmann brains” by Andreas Albrecht and Lorenzo Sorbo….

In a 2004 paper, Albrecht and Sorbo discussed “Boltzmann brains” in their essay:

A century ago Boltzmann considered a “cosmology” where the observed universe should be regarded as a rare fluctuation out of some equilibrium state. The prediction of this point of view, quite generically, is that we live in a universe which maximizes the total entropy of the system consistent with existing observations. Other universes simply occur as much more rare fluctuations. This means as much as possible of the system should be found in equilibrium as often as possible.

From this point of view, it is very surprising that we find the universe around us in such a low entropy state. In fact, the logical conclusion of this line of reasoning is utterly solipsistic. The most likely fluctuation consistent with everything you know is simply your brain (complete with “memories” of the Hubble Deep fields, WMAP data, etc) fluctuating briefly out of chaos and then immediately equilibrating back into chaos again. This is sometimes called the “Boltzmann’s Brain” paradox.

[…]Now that you understand Boltzmann brains as a concept, though, you have to proceed a bit to understanding the “Boltzmann brain paradox” that is caused by applying this thinking to this absurd degree. Again, as formulated by Carroll:

Why do we find ourselves in a universe evolving gradually from a state of incredibly low entropy, rather than being isolated creatures that recently fluctuated from the surrounding chaos?

Unfortunately, there is no clear explanation to resolve this … thus why it’s still classified as a paradox.

Naturalists like to propose the multiverse as a way of explaining away the fine-tuning that we see, and explaining why complex, embodied intelligent beings like ourselves exist. But even if the multiverse hypothesis were true, we still would not expect to observe stars, planets, and conscious embodied intelligent beings. It is far more likely on a multiverse scenario that any observers we had would be “Boltzmann” brains in an empty universe. The multiverse hypothesis doesn’t explain the universe we have, which contains “a hundred billion galaxies with a hundred billion stars each” – not to mention our bodies which are composed of heavy elements, all of which require fine-tuning piled on fine-tuning piled on fine-tuning.

William Lane Craig answered a question about Boltzmann brains a while back, so let’s look at his answer since we saw what his debate opponent said above.

He writes:

Incredible as it may sound, today the principal–almost the only–alternative to a Cosmic Designer to explain the incomprehensibly precise fine tuning of nature’s constants and fundamental quantities is the postulate of a World Ensemble of (a preferably infinite number of) randomly ordered universes. By thus multiplying one’s probabilistic resources, one ensures that by chance alone somewhere in this infinite ensemble finely tuned universes like ours will appear.

Now comes the key move: since observers can exist only in worlds fine-tuned for their existence, OF COURSE we observe our world to be fine-tuned! The worlds which aren’t finely tuned have no observers in them and so cannot be observed! Hence, our observing the universe to be fine-tuned for our existence is no surprise: if it weren’t, we wouldn’t be here to be surprised. So this explanation of fine tuning relies on (i) the hypothesis of a World Ensemble and (ii) an observer self-selection effect.

Now apart from objections to (i) of a direct sort, this alternative faces a very formidable objection to (ii), namely, if we were just a random member of a World Ensemble, then we ought to be observing a very different universe. Roger Penrose has calculated that the odds of our solar system’s forming instantaneously through the random collision of particles is incomprehensibly more probable that the universe’s being fine-tuned, as it is. So if we were a random member of a World Ensemble, we should be observing a patch of order no larger than our solar system in a sea of chaos. Worlds like that are simply incomprehensibly more plentiful in the World Ensemble than worlds like ours and so ought to be observed by us if we were but a random member of such an ensemble.

Here’s where the Boltzmann Brains come into the picture. In order to be observable the patch of order needn’t be even as large as the solar system. The most probable observable world would be one in which a single brain fluctuates into existence out of the quantum vacuum and observes its otherwise empty world. The idea isn’t that the brain is the whole universe, but just a patch of order in the midst of disorder. Don’t worry that the brain couldn’t persist long: it just has to exist long enough to have an observation, and the improbability of the quantum fluctuations necessary for it to exist that long will be trivial in comparison to the improbability of fine tuning.

In other words, the observer self-selection effect is explanatorily vacuous. It does not suffice to show that only finely tuned worlds are observable. As Robin Collins has noted, what needs to be explained is not just intelligent life, but embodied, interactive, intelligent agents like ourselves. Appeal to an observer self-selection effect accomplishes nothing because there is no reason whatever to think that most observable worlds are worlds in which that kind of observer exists. Indeed, the opposite appears to be true: most observable worlds will be Boltzmann Brain worlds.

Allen Hainline explained some of the OTHER problems with the multiverse in a post on Cross Examined’s blog. I recommend taking a look at those as well, because I feel funny even talking about Boltzmann brains. I would rather just say that there is no experimental evidence for the multiverse hypothesis, as I blogged before, and leave it at that. But if the person you are talking to fights you on it, you can disprove the multiverse with the Boltzmann brains.

Polemics

Are atheists right to say that you can’t prove a universal negative like “God does not exist”?

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I hear a lot of atheists complaining that they shouldn’t have any burden of proof because it is impossible to prove a universal negative, i.e. – “there is no God”.

Here’s a post from William Lane Craig about it.

Excerpt:

The first claim is, ironically, usually found on the lips of atheists, who thereby seek to excuse themselves from bearing any share of the burden of proof in the discussion. Usually, the claim is that a universal negative cannot be proved, and therefore the claim that “There is no God” is unprovable. The second claim is typically given as the reason why a universal negative cannot be proved: no matter how much knowledge you have acquired, there will always be more facts that you do not yet know, and perhaps the exception is among them. So one can never prove that there is no God. Perversely, this is somehow interpreted, not as an admission that atheism is indefensible, but as a demonstration that it is in no need of defense!

Unfortunately, the argument is misconceived on a couple of counts.

First, negative, universally quantified statements can be proved. We do this all the time. When we make statements about “all” or “none,” we are speaking about what is the case with respect to a certain domain. We are saying that all or none of the members of that domain have or has a certain property. If the domain is not too large, I can confidently make universally quantified affirmative and negative statements. For example, I am quite confident that “No U.S. Senator is a Muslim.” Or again, if I have a typical sample of the domain, I can make inductive inferences on the basis of the evidence from the sample to the whole, even if the whole domain is too large for me to canvass; for example, taking as my domain all the microbes on Earth, I can confidently assert, “No microbes have brains.”

Now someone might say that while it is admittedly true that negative, universal statements can sometimes be proven, still the point remains that in the case of God, the domain is too large and our sample too small to come to any negative conclusion. But those who propound this argument seem to think that the way one determines whether God exists is by taking a sort of universal survey to see if anything answering to the description of God exists somewhere out there. There are, however, other ways of coming to a knowledge of negative, universally quantified statements than doing an inductive survey.

For example, we can have knowledge of negative, universally quantified statements on the basis of things’ essential properties; for example, “No water molecules are composed of CO2.” (Even if something looked and behaved just like water but was made of CO2 , it still would not be water but just a look-alike substance.) Or if we could show that a notion is logically impossible, we would know that it does not exist; for example, “There are no married bachelors.” Significantly, many atheists have tried just this route to proving that God does not exist, arguing that the idea of a being which is all-powerful or all-knowing is logically incoherent.

[…]Second, the statement that “God does not exist” is not a universally quantified statement. When the theist asserts that “God exists,” the word “God” is being used as a proper name, not as a common noun. It is not a statement like “Dogs exist” but rather like “Lassie exists.” In order to prove that God does not exist, one need not prove that there are no gods whatsoever. Our interest is in one specific being, not in all the other beings which may have been imagined or worshipped throughout the world. So the claim that “God does not exist” is really a singular claim, like “Sherlock Holmes does not exist” or “Harry Potter does not exist.” No one thinks that negative, singular claims cannot be proven.

So there are two ways to disprove a universal negative. Look where you expect the thing to be evident, and show that the evidence is not there. For example, show evidence that the universe is eternal. You can’t have a Creator if you can show evidence that the universe is eternal. The second way is to show that the concept of God is logically contradictory, e.g. – that the concept of a “timeless person” is self-contradictory. Scholarly atheists try to do this, but this has not filtered down to the rank and file, which is why they still hold to these atheist slogans like “you can’t prove a universal negative”. Of course you can.

And finally, Craig concludes with some good advice:

The bottom line is that we have no choice but to go on the basis of the knowledge and evidence that we do have—just we do in all other affairs of life.

Rank and file atheists seem to be very keen on holding out for today’s scientific and historical data to be overturned by Star Trek theories of the future. But the more we study the good, scientific arguments for God’s existence, the harder it is for naturalism to account for it. I am talking about the origin of the universe, the cosmic fine-tuning, the habitability argument, the origin of life, the origin of phyla, scientific evidence for consciousness and free will (e.g. – mental effort) and so on. Not to mention other arguments like the moral argument and the minimal facts case for the resurrection of Jesus.

We have to decide on the data we have now. And the data we have now fits better with a theistic worldview than an atheistic worldview. I can imagine all kinds of data that would argue against Christian theism. Finding the bones of Jesus. The universe being eternal. Experimental evidence for the multiverse. A probable naturalistic scenario for the origin of life. Etc. Arguing against Christian theism is not hard, it just takes work. That’s why intelligent and informed atheists like Peter Millican and Austin Dacey can do it, but rank and file atheists want to talk about “I lack a belief in God” and “I can’t prove a universal negative”.

No one is asking atheists to prove anything, just as theists don’t prove anything. We are asking them to give logical arguments with premises that are supported by the evidence. And that’s what we expect theists to do, too. Once we have all the arguments and evidence on both sides, then people can decide for themselves. You don’t have to “prove” anything in a debate, you just have to state your case as persuasively as possible and the other side does the same, then people decide. Simple.

UPDATE: My favorite atheist Jeff Lowder mentioned this post from Internet Infidels which is on the same topic. His perspective is always worth reading.

UPDATE: And my friend John Fraser has some thoughts on evidence for and against God.

UPDATE: My FB friend Bruce sent me this video:

It’s William Lane Craig answering the question in a debate situation.

News

IRS auditing conservative news provider Breitbart.com

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Yes, the same IRS that targeted Tea Party groups in order to help Obama win re-election.

Ted Cruz wrote a letter to the IRS about the audit, and you can read it here on the Breitbart web site.

Excerpt:

Dear Commissioner Koskinen:

I write to express deep concern over the recent announcement by Breitbart News that the Internal Revenue Service recently notified the Breitbart News Network, LLC that it would be subject to a far-reaching, burdensome, and open-ended audit.

As you know, the Breitbart News Network LLC is a conservative-leaning press outlet. It has editors and reporters who cover daily political news and regularly breaks stories that are critical of the Obama Administration’s policies. To conduct this audit, Breitbart News Network, LLC was asked to provide the IRS with all of its organizational documents, financial records, W-2s, W-4s, 1099s, and K-1s filed, personal income tax returns for each member of the company, payroll tax forms, information regarding properties and assets acquired by the company, bank statements, and array of other records documenting revenues, expenses, and depreciation costs.

This media audit, coupled with the recent proposal of 49 Senate Democrats to amend the Constitution to give Congress plenary power to regulate political speech, paints a disturbing picture of a coordinated assault on the First Amendment.

In another time, under another Administration, the decision to audit a conservative news organization might not have risen to a worrisome level of concern. However, given the IRS’s disturbing track record of illegally targeting conservative organizations-including the IRS recently paying a $50,000 settlement for having wrongfully leaked a conservative group’s confidential tax information-and the persistent refusal by the current Department of Justice to meaningfully investigate or prosecute those crimes, the decision to audit Breitbart News Network, LLC appears highly questionable.

For the IRS to behave like a partisan political organization, targeting media organizations whose views differ from the President’s, would represent a gross abuse of power. It would undermine the statutory mission and integrity of the IRS. And it would likely subject IRS employees to criminal prosecution.

The rest of the letter is Ted Cruz’s questioning of the IRS for their actions. It’s cases like this that make me want to abolish the entire IRS and go with a two-tier flat tax system with almost no deductions. Put the corrupt bureaucrats out of a job. That’s the only thing they will understand – the unemployment line.