## Monday, April 14, 2014 ... //

### Andrei Linde: universe or multiverse?

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.

#### snail feedback (30) :

In the universe versus multiverse debate, it seems to me that even if there is a multiverse then the proponents of the unique universe could always claim that the alleged multiverse is merely the universe's mechanism for constructing quantum probability waves.

Henry Ford said you could get a Model T car in any color . . . so long as it was black.

I prefer this quote from Henry Ford: "It is well enough that people of the nation do not understand our banking and monetary system, for if they did, I believe there would be a revolution before tomorrow morning."

Not a bad quote, but of course it doesn't answer Lubos's question. Actually, I don't know for sure whether mine quote answered it either. :)

Given the relative non-outrage over Edward Snowden's revelations, and the outrageous statements by Jamie Dimon and Lloyd Blankfein to do with their "banking" activities, I think that Henry Ford's quote is bunk. Many people do understand. They are just too cowed and too incurious, too harassed, to react...rather sad.

Banks, like most other companies, have assets, Gordon. The idea that if a bank were to go broke that it would bring down the entire economy is a lie to con people into signing off on taxpayer bailouts. True, some steps would need to be taken to prevent a panic, but that could be handled. Those assets would be purchased by someone else - the bank would get a new name on the wall and the stockholders, bondholders and perhaps even some depositors would lose some or all of their money, but they should. To ask taxpayers to bail out failed institutions of any kind is a gross distortion of capitalism and cannot be sustained. Even worse, the fear of a bankruptcy can be used as cover for not being responsible for bad decision, and perhaps even criminal activity. Not fair for depositors, you may ask? Well, if depositors held their banks accountable for bad decisions, or something worse like criminal activity, you can bet things would shape up very quickly.

Ford knew that his inexpensive cars would have to sit outdoors, unlike rich folks fancier automobiles, which have always been garaged, and that black was the only color that would withstand continuous exposure to the sun and the elements.
Automobile paint technology has progressed enormously over the past century but black remains the most durable car color today due to the fact that its pigment, graphite, readily absorbs actinic radiation and is enormously stable chemically.

Perhaps, Gordon, people are outraged over Snowden’s actions and not his revelations for good reason.

When Americans understand that our government, not terrorism, is the biggest threat to our security, they’ll understand why whistleblowers are heroes and not traitors.

The Fourth Amendment provides the right of the people to be SECURE against unreasonable search and seizure. Unreasonable search and seizure by our government, not by terrorists.

No one is safe without an effective Bill of Rights, no matter how “law-abiding” you think you are. You criticized the government in a phone conversation with a relative? You are aiding the enemy! Your neighbor has a grudge against you? Hello, you just got denounced as a terrorist! Now prove you’re innocent if you can, while you're in preventive detention with no access to a lawyer.

Whistleblowers like Manning and Snowden are protecting us from the real threat, not endangering our security. The sooner Americans wrap their heads around that crucial message, the safer we’ll all be.

Is Linde's theory of eternal inflation physics or metaphysics? Does it obey or violate Occam's razor? Laplace famously remarked to Napoleon that God was not a necessary hypothesis for doing science. Is that equivalent to assuming that the observed laws of nature are what they are purely by chance, and that therefore there must be a near-infinite number of different universes? How is one assumption any more (or less) scientific than the other? Which comes back to the question of whether this is physics or metaphysics?

It would seem to me that, at this point in time, it is purely a matter of taste whether or not one favors the multi-verse idea. Personally I don't care. My own take on the Hebraic conception of God is not that of an Intelligent Designer who necessarily created the universe, even though that is what philosophers and theologians seem to always have in mind.

Rather it is an anthropomorphic personification of the idea of karma: that everybody gets what they deserve in the end in some moral sense. This might (or might not) be true even if there is no Intelligent Designer or Creator God. It could be built into the laws of nature in ways we do not (yet?) understand, possibly relating to the correlative nature of pleasure and pain.

Bottom line: the idea of God which has actually had an influence in the history of the West is a moral idea, not a physical one. This was the gift of the Hebrews.

It is physics as long as one may collect evidence for or against it, and it is surely true in principle not just for ordinary inflation but for eternal inflation or any other "special kind" of inflation.

Is that OK with Occam's razor? It depends what you mean by Occam's razor. People believe lots of irrational and wrong things that they may call Occam's razor. If you only mean Occam's razor that is actually a valid principle in science, eternal inflation is in perfect agreement with it.

Occam's razor - the correct one - only says that the theory shouldn't have many independent arbitrary assumptions or independent basic building blocks. Eternal inflation is perfectly Occam's razor-friendly in this sense. It is a very concise compact theory. The fact that it predicts huge universes or many universes is a *consequence* of the simple, Occam's razor-friendly postulates. Theories can predict whatever they can, and they are indeed encouraged to do so. In science, one may only eliminate theories that actually contradict some evidence. If they're not falsified, they are perfectly viable, and the simpler and more coherent its starting point or defining equations are, the more convincing the theories will be.

Sorry, I will skip the whole tirade about God because I would have nothing constructive to offer to Her or Him or It or Them.

This is for you, Cynthia-- Matt Taibbi, the author is the Goldman-Sachs is a vampire squid with its blood funnel...quote...commented that he finally has found someone who hates GS even more than he does :)
http://www.maxkeiser.com/2010/04/max-keiser-the-goldman-sachs-are-scum-video/

I wonder why they dont realize that the govt is the biggest threat to their security---the Founding Fathers certainly did...lots of Franklin and Jefferson quotes warning about the dangers of govt.
I am willing to bet that even Orwell, if he were alive today, would be astonished at how far beyond "1984" we have gone.

There's an entertaining panel discussion with Alan Guth and Andrei Linde vs Neil Turok and Andreas Albrecht from 2013. Which i think is fun to watch in retrospect, after the BICEP result.

I respect your opinion, Gordon, but Snowden willfully broke the law and deliberately violated employment terms that he had contractually accepted. I do not lightly dismiss his revelations and I would not like to think that anyone had been harmed by NSA's metadata collection but Snowden ought to have followed the law. He had no right to destroy a tool which may well have been useful and might have remained even more useful in the future. I do think he should stand trial for treason. Of course he is innocent until and if he is convicted in a court of law.

I watched Linde’s SETI speech a couple of weeks ago and found it to be superbly entertaining. He is an absolute delight.

Linde’s theory is physics, of course, but remember that phenomena that do not lie within our light cone cannot be addressed experimentally. Nonetheless, it is perfectly valid to construct theories of things that have no causal relation to us and even use these theories to generate falsifiable predictions. It’s still physics.

Gene--I think of him more as a whistleblower, but my point is that regardless of how one views his actions, whistleblower, or treason, his revelations about the ubiquity of the indiscriminate spying on citizens without cause on an unprecedented scale is, to me at least, enormously troubling. It is institutional paranoia. How could Snowden have followed the law? Whistleblowers have been aggressively prosecuted by the Obama admin. and not protected, as Obama promised.
A promise about protecting whistleblowers used to be on his webpage along with other election promises, but disappeared from it after Snowden's revelations.
Have you read articles about the various programs on Pierre Omidar (e-Bay founder) funded online newszine, The Intercept (Glenn Greenwald)?
The US is not the only country that has gone nuts--the CCTV cameras, millions of them in the UK are a frightening violation of privacy---there are 32 of them in a one block radius of George Orwell's London house.

I finally watched this whole debate, fun! Linde says some of the same things as in the 2012 SETI talk but it's still persuasive and witty, and so is Guth. Turok is largely reduced to babbling about "falsifiability" which he doesn't apply to his claims at all because to say that there aren't other universes is at least equally unfalsifiable. In fact, the inflation-related things are much more connected with the empirical data than whatever Turok and Albrecht were saying.

"The man asks the question whether entanglement between particles in 2 universes can exist." This is IMO indeed an important question because these universes could be each others ANTI-COPY (CP) symmetric sisters without a cat paradox?

Anyhow, Linde did not perceive the word "entangled" correctly (the questioner's diction was not that clear) and he slipped away from having to try to ask the question. I was interested to see if he had any kind of string/M-theoretical intuition whereby to answer it. (I confess I don't not believe he or anyone else has anything substantial to say about it.)

By what I have always meant by the AP, I felt Linde argued superbly for it. Clearly better than I have ever done. ;-)

Thanks Lubos for giving more background here on BICEP2 and Linde

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From reading this comment, it seems to me that confused laymen (and other not so lay anti theoretical physics activists) always wrongly apply "occams razor" to the predictions or results of theories, instead of to the defining principles and basic ingredients at the root...

Exactly. It is a common misconception. When a theory allows one to study many things, many different objects because it has many different solutions etc., some people are scared by the large amount of knowledge involved and they invent the story that the theory must "contradict Occam's razor" although the power and reach of the theory is either neutral or, in some cases, a strength.

Thanks for your response. I see what you mean. Still, I would be even happier if String Gas Cosmology turns out to be a better fit with the evidence. Not that nature cares about my happiness!

Dear Luke, I would be happy, too - if it *really* turned out to match the evidence more accurately than anything else. By the word "really", I mean that I could verify that it's actually the case, rather than that someone - however nice and smart - would just claim such a thing. ;-)