Anthropic Thoughts

Irony has a way of extracting it's own revenge. A while ago, I posted a claim that Luboš was regrettably irony challenged. Naturally, it didn't take long for me to wind up hoist with my own petard. First, the setting - Luboš's post on Raphael Bousso's talk on the Stringy Landscape. In particular, in the comments Luboš said:

So the choice is rather clear. Either the observed value of the vacuum energy has more or less a calculable value that is, because of some mechanism, much smaller than the available calculations today. This means an extraordinary hypothesis and a big discovery waiting for us that may show that most of the things we know that work could be accidents and the vacuum energy follows rather different rules than what QFT/ST lead us to believe. Such a solution will avoid the points raised by Polchinski, Bousso, and others by an argument that will surely look like a shocking miracle to them.

Or you accept that the value of the vacuum energy is more or less a random number without a satisfactory explanation. Accepting this adjective "random" inevitably leads to thinking about details of these anthropic scenarios - the definition and origin of the randomness and their incorporation into more accurate theories we use for the Universe - and leads to Bousso's or Vilenkin's talks or other talks and papers.

Again, anyone who denies that these are the only options that exist is a crackpot.

Now I would essentially agree with this, since what Luboš has said in the first two paragraphs is just that either the vacuum energy value has some deep explanation or that it doesn't - his last sentence is just one of his random brain farts.

Another point arose in the comments. It was asserted that Bousso had assumed that the Universe started in a low entropy state. Lumo responded by citing some authorities:

...Penrose argued many years ago that the beginning must have a low entropy. Do you really have any reasons to doubt that the newly created Universe had a low - and I would probably say zero - entropy?

I found this a bit ironic, since Lumo has elsewhere called Penrose a crackpot. It ought to be mentioned that Prof Motl's estimate of the early entropy of the Universe is a very strange one, since big bang theory suggest that the early Universe consisted of a hot and highly uniform soup of particles. Hot plasmas have very high entropies, by terrestial standards, as a simple consultation of some Freshman physics texts will show. The oddity, as Penrose has emphasized, is that the Universe apparently started in a highly special state where the gravitational degrees of freedom were *not* thermalized. See, for example, Chapter 27 of his book The Road to Reality. There is no known explanation for this fact, though Penrose has hazarded some guesses.

My ironic error was attempting to call Lubos's attention to this fact as follows:

The initial low entropy of the Universe is yet another proof of Anthropicity, no doubt. Or, if you are [a] crackpot like Penrose, you might assume that it is due to some deep but yet unclear principle.

Naturally, my reference to Penrose as "a crackpot" was purely ironic, as I consider him one of the deeper thinkers on physics. It was intended to be an ironic reference to Lumo's categorization of Penrose as such. Here, the irony gods got even, since, *of course* Luboš missed the irony.

His reply:

Dear CIP, I don't think that there is any important correlation between the (likely) fact of a low-entropy beginning of the universe on one side, and the (hypothetical) anthropic scenario on the other side. Your comment just shows that you want to separate all ideas and all people in the world to two groups with different signs, which shows that you may be computationally equivalent to a 1-bit computer with 1 bit of RAM which may be insufficient to join discussions about theoretical physics, roughly by 15 orders of magnitude.

So does it really take a petabit (10^15 bits) of random access memory to discuss physics? Let's hope not, since even Witten is more likely to top out a factor of a million or so short of that.

Isn't it ironic that Luboš, of all people, would accuse me of partitioning the world into just two equivalence classes.

Let me not resist pointing out a final irony. By the logic of Lumo's original quote in this post, the strangely low initial entropy of the Universe must either be the result of a deep principle, or an incredibly improbable anthropic coincidence - and the number of possible initial states of much higher entropy is large even compared to the number of stable minima estimated to populate the moduli space of the landscape.

I would guess that Luboš is aware that the so-called The Anthropic Principle long predates the crisis of the landscape, and even string theory itself - but he doesn't seem to recognize it.