Some time ago, before the BICEP2 discovery (in July 2012, weeks after the Higgs discovery), Andrei Linde gave an 82-minute talk at SETI, a center to search for ETs.
Because Linde and his theories – even some more specific theories – seem to be greatly vindicated by the BICEP2 announcement, it may be interesting to listen to his more general ideas about the subject. Linde is a pretty entertaining speaker – the audience is laughing often, too.
He starts with jokes about the word "principle" and comments about the cosmological principle, the uniformity principle, the big bang theory, possible global shapes of the universe and fates of the expanďing universe, and so on.
Linde employs plain English – with his cute sofťish Russian accent – to clarify many stupid questions. Why are so many people doing SEŤI? Why is the universe so large? Why energy is not conserved in cosmology?
But he ultimately gets to the multiverse and other controversial topics near the cutting edge. Amusingly enough, Linde mentions Hawking's old proposal to explain the uniformity of the universe anthropically. If it were non-uniform, it would become lethally non-uniform, and we couldn't live here and ask stupid questions. Except that Linde shows that Hawking's explanation doesn't really work and there is a more satisfying one, anyway.
Linde is surprised that the simple solutions for inflation etc. were only understood so recently, 30 years ago or so. He spends some time by explaining why the young universe was red (he is from Russia) or black (Henry Ford:I didn't quite understand this remark on Ford LOL: but the final point is that a largely expanded universe looks color uniform even if it is not). Linde prefers to believe in the multiverse (containing inequivalent vacua) because diversity is more generic.
At the end, he talked about the cosmological observations as a "time machine", the fractal nature of the universe, the cosmological mutation arising from the landscape etc. Some of his humor is childishly cute. The regions of the multiverse are separated not by border patrols but by domain walls and if you are young enough, energetic, and stupid, you go through the wall and die. ;-) Around 53:00, string theory is finally discussed, with the claim that there are 10500 colors of the universe. KKLT. Users of iPhone are parts of the silicon life created in the Silicon Valley.
Guth made a comment about the free lunch and the Soviet man Linde was deeply impressed by the free lunches. So he improved the inflation as the eternal feast where all possible dishes are served. ;-)
During the talk, Linde says lots of philosophical things about verification of theories etc. He knew inflation was right but he didn't expect that proofs would be found. So he was amazed by the experimenters. Concerning the "unfalsifiability" claims, he debunks them by saying that not even the U.S. courts work in this way. For example, a murder (of his wife) suspect is not given a new wife and a knife to repeatedly try whether he would kill her again. ;-) They just eliminate options and release a verdict. But reasoning doesn't require repeatable experiments.
Around 1:10:00, he spends some time with funny musings about Einstein's "the most incomprehensible thing about the Universe is that it is comprehensible", Wigner's "incredibly efficient mathematics", and some comments about the unexpectedly inefficient biology. Those things are explained anthropically as tautologies, too. Physicists can't exist at places where physics doesn't work etc. That's nice except that millions of things we have already understood also have a better, less tautological, more unequivocal, and more nontrivial explanation, and the same may be true for many currently unexplained patterns in Nature, too.
Questions begin at 1:12:55. Someone is puzzled whether Linde is for or against the anthropic reasoning. He is against the non-inflationary anthropic arguments. In inflation, things are different. He says that 10500 options is much better than the single 1 candidate on the Soviet ballots. ;-) In the second question, he explains that we know the theory of structure formation that produces the right filaments etc.; the small non-flatness of the spectrum is important in that, too. Someone with a seemingly similar Russian accent asks whether the initial wave function of the universe applies just to our universe or the whole multiverse. I think that Linde didn't understand the question so he talked about the many-world interpretation of quantum mechanics (just an interpretation, not a key insight etc.; MWI ignores the key role of conscious observers in QM, and so on; I completely agree with Linde here, even though he is answering a wrong question). The man asks the question whether entanglement between particles in 2 universes can exist. Linde says it can but he says it can exist on 2 islands. However, the entanglement behind the cosmic horizon may be unphysical due to the cosmic horizon complementarity principle, I would add.
At any rate, a fun talk.