The bottom line, “OK, who’s playing silly buggers?”

the egg in the midlle = our present state

most probable Past and Future to the left and right – should be symmetric!

the fact that our actual Past is very different represents a puzzle that need to be explained

If we read in a few frames where the arrows are, with greater structural density towards the middles of each chain of arrows, do we also have a diagram (of an analogy) of the evolution of two FLRW universes where Omega > 1 and where the bottom one is a conventional “Big Crunch/Big Bang” oscillation while the top one has much more dark energy?

Stupider question: how would one distinguish between being in the lower type of Universe from being somewhere in a longer chain comprising these two subchains at a time after an expansion from a period where the universe is hot and dense enough for GUT physics and some later period hot and dense enough for BBNS?

Stupidest question: can they be linked together in a chain in the sort of “extra-universe filled with multiple universes following different arrows of time” model you have been exploring?

Waaaay out there: is there an equivalence between a fluctuation model where a Boltzmann Brain and its environment appears “ex nihilo” and a continuous model where we only at a few selected points along a timelike axis? (I.e., in your diagrams do we have snapshot at sparsest boundary condition, snapshot at some intermediate point on the order of tens of Gy before the hottest densest boundary condition, a snapshot at the hottest densest boundary, another snapshot at some intermediate point on the order of tens of Gy after the hottest densest boundary condition, and a snapshot at the sparsest boundary; or do we definitely have a diagram as described in Jason and Ted’s comments, and as criticized by “Fluctuation”‘s comment?)

I’m in the final throes of book-writing

Just how fast do you work?!!

Which came first?

The intact egg ALWAYS comes before the broken egg… right?
_{BJM Says:
March 18th, 2009 at 10:48 pm}

Define “before”.

I do not dispute the claim that the early universe was in a state of fantastically low entropy.

I do dispute the claim that a Boltzmann fluctuation can explain that. Who claims that anyway?

The whole point of the Boltzmanns Brains argument is that a Boltzmann fluctuation can explain the universe one observes only if solipsism is true. Obviously you should look elsewhere for an explanation.

That’s not to say that most physicists believe that the universe arose spontaneously as a statistical flucuation, of course. Just that if you don’t believe it did, this argument is not the way to go about proving it.

Just like to correct you there: there is nothing speculative about what Sean is driving at here. The early universe was indisputably in a state of fantastically low entropy, and nowadays very few people would dispute Sean’s claim that a Boltzmann fluctuation can explain that. True, Sean does have some speculative ideas about how to *explain* that extraordinary state of affairs, but that is a different matter. In short: what Sean is pointing to here is neither speculative nor controversial.

There *is* a sort of pseudo-controversy raised by certain cranks who deny that the origin of the second law of thermodynamics is to be found in cosmology. But that’s a “controversy” of precisely the same kind as the creationist “controversy”.

It is not PG13 though, so I suspect it won’t be in Sean’s book .

(The answer is : the cock came first).