Susskind’s Response to Mithani and Vilenkin: Let’s Play Pretend

Alex Vilenkin has been a staunch supporter of a temporally finite universe.  In spite of the numerous papers and lectures he has given showing that the universe cannot avoid a beginning and the “eternal” models are only eternal into the future, many atheists refuse to acknowledge that all of physical reality had a beginning and are still arguing that it is has an eternal past.  Even Alan Guth, who is the “G” in the BGV Theorem, says they have been able to “prove” the universe had a beginning, yet he still thinks it may be eternal.  I have often wondered what other scientists say about Vilenkin’s work, since if he had made a significant error in his analyses of the other models, surely someone would have said something more than quibble over what constitutes a beginning.

I came across a short paper by Leonard Susskind where he responds to the paper, “Did the universe have a beginning?” by Mithani and Vilenkin which I summarized here (spoiler- the answer is Yes!).  Susskind is a popular physicist that makes frequent appearances on science programs like Nova.  In this paper, he “will argue the opposite point of view; namely, for all practical purposes, the universe was past-eternal.” 

 

He uses a thought experiment of a semi-infinite city called, Hilbertville, to represent the multi-verse.  It has a boundary at x=0, but the goes to infinity at x>0.  The observers of Hilbertville are trying to see the boundary of the city.  Those close to the boundary can see it, but those who are very far away cannot.  Since most of the observers will statistically be too far away to see the boundary of the city, he concludes the city may as well not have a boundary and the same goes for a beginning to the universe.

“Combing the Mithani-Vilenkin's observations with the ones in this note, we may conclude that there is a beginning, but in any kind of inflating cosmology the odds strongly (infinitely) favor the beginning to be so far in the past that it is effectively at minus infinity.”

Susskind didn’t say Mithani and Vilenkin were wrong in their analyses of other model types.  Susskind agreed the evidence indicates there was a beginning.  Instead he said the beginning of the universe (or multi-verse) was probably so far in the past that the universe may as well be eternal for us observers on Earth.  That’s akin to saying ‘the evidence says there was a beginning, and while I acknowledge that’s the evidence, I can still pretend there wasn’t a beginning and ignore all implications of a beginning’.  Atheists get upset when Christians quote Romans 1 and claim they suppress the knowledge of God, but with a response like this, can you blame us?