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    Smolin Vs Susskind: Part 3 Ripping On Lenny
    By Sascha Vongehr | December 7th 2010 10:35 PM | 7 comments | Print | E-mail | Track Comments
    About Sascha

    Dr. Sascha Vongehr [风洒沙] studied phil/math/chem/phys in Germany, obtained a BSc in theoretical physics (electro-mag) & MSc (stringtheory)...

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    This is PART III of the four part series about the Edge discussion between Lee Smolin and Leonard Susskind. After criticizing Smolin the last time in PART II, it is now time to turn on Susskind.

    Leonard Susskind is well read, certainly enough to know about the measure (not “measurement”) problem in modern quantum physics (introduced in PART I). Nevertheless, he argues against Lee Smolin by telling him that eternal inflation makes “more” universes, which without a good measure, like some density, a number per volume or suchlike, is perfectly senseless. Moreover, and as discussed before, what if you make another billion dead universes for every one like ours? It doesn’t change anything except eliciting the feeling that we are uncommon, which Susskind wants to elicit in order to have a case for applying anthropic principles.

    Yeah, sure we are uncommon if you count enough dead stuff. However, it certainly does not address the fact that Smolin is already on the next level by demanding more careful consideration of how your statistical ensemble is constructed and what you want to do with it. It only tricks the reader into a side issue.



    Leonard Susskind provides bad analogies: When Lee Smolin talks about that some knowledge cannot be had on principle, Susskind replies that if we had thick clouds and could not see the stars, then we would have likely argued similarly about not being able to see the stars. All his analogies, for instance the one mentioning Darwin and not being able to investigate the fossil record yet, and the many other, gratuitous examples, fail badly, because cloud covers and suchlike you can always hope to pierce through eventually.

    However, a black hole event horizon, once you fall through, is something you cannot look back through on principle. On what principle? On the very principle that Susskind defends so vigorously when it comes to black holes conserving their information: You can on principle not copy quantum information. This is not a little hurdle you can hope to overcome with further advancements in technology; it is a hurdle that underlies the whole darn fundament of physics and thus reaches epistemological relevance.

    We are dealing with the Kantian a priori, the absolute no go, not just with silly Mach opining that atoms will be forever unobservable. Does Leonard Susskind know about this difference between not-yet-observable and on-principle-unobservable? Of course he does! He himself partially discovered black hole complementarity and the holographic universe. This leaves two possibilities: He either argues disingenuously or he is effectively (Without realizing, like too many physicists) a direct, naïve realist, as somewhat discussed in PART I.

    Without realizing” means here that although he partially was personally involved in dismantling realism, he just cannot shake it [Such happens often at the cutting edge of research – Einstein helped discover quantum mechanics but also never believed (grasped?) its core.].

    There are many other little remarks that could be made, like that he disregards (in attacking Smolin at some point) the fact that information in a black hole is only shown to be conserved in theories that have some sort of absolute quantum time, and so on. However, listing those would distract from the important points above, which are so important since they reveal either a dishonest or naïve Susskind, and this is something that I write not without difficulty about somebody who was my absolute hero just ten years ago.

    After I ripped on both contenders, next time the judge’s decision as if anybody cares. ;)


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    Comments

    Ladislav Kocbach
    And how many angels can dance on the head of a pin?  Can not wait till part IV! Physics and the anthropic principle and the dead Universes with a finite (or perhaps infinite) density,
    meaning a "number per volume or suchlike" just to quote ....
    This is real fun! Keep the style
    Bonny Bonobo alias Brat
    I find it a bit odd that in the Edge simultaneous discussion papers Susskind wrote :-
    Over the last decade, since Smolin put forward his clever idea, the black hole controversy has largely been resolved. The consensus is that black holes do not lose any information. I'll cite some of the most influential papers that you can look up yourself: HEP-TH 9309145, HEP-TH 9306069, HEP-TH 9409089, HEP-TH 9610043, HEP-TH 9805114, HEP-TH 9711200. Incidentally, the combined total number of citations for these six papers is close to 6,000.
    But he doesn't mention that he is either the author or co-author of all six of these papers! A bit misleading I think.
    My latest forum article 'Australian Researchers Discover Potential Blue Green Algae Cause & Treatment of Motor Neuron Disease (MND)&(ALS)' Parkinsons's and Alzheimer's can be found at http://www.science20.com/forums/medicine
    socrates
    Good catch, Helen!
    Citizen Philosopher / Science Tutor
    vongehr
    Well spotted indeed and nicely supporting my point and PART IV, too.
    rholley
    So!  Which of the two shall we send to Smolinsk?
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    socrates
    In reading Susskind's letter, I am reminded of the Einstein vs Bohr debate, all over again (where Smolin plays Einstein and Susskind plays Bohr). The tone and strategy of Susskind's argument suggests to me a greater interest in winning the argument and hence putting the issue to rest, than in reaching a deeper understanding of the workings of nature, beyond what we already know.

    The anthropic principle in cosmology, like the Copenhagen interpretation of quantum mechanics, strikes me as a kind of "cop-out" or excuse to avoid further thinking on the matter.

    I am very intrigued by Smolin's natural selection approach as applied to cosmology and Susskind does raise at least one criticism that does strike me as significant. That is the question Sascha mentioned above - the question of passing on information from the parent black hole to the "baby" universes analogous to parents passing DNA on to their children. Is this possible. Susskind says it is not. Is this true?

    I am aware of the principle of conservation of energy, but I am not aware of any principle of the conservation of information. Indeed, it is an everyday fact that intellectual property can be easily copied and thus "stolen" without actual loss of the original. To use Susskind's analogy to biology, a parent does not lose their own DNA when passing their DNA on to their offspring. So why does he speak of information being lost from the parent black hole in Smolin's proposed spawning of baby black holes. Remember, information and matter can flow into a black hole, even if nothing can flow out. Therefore information can flow into the baby black hole from the parent black hole, just like the parent black hole can receive information from the universe that contains it. Perhaps Susskind did not see the implied nested nature of Smolin's hierarchy of nested universes, or "pocket universes".  (Here, on the point of linguistics, I have to agree with Susskind - the term "pocket universe" makes more sense than referring to "multiple universes".)

    Citizen Philosopher / Science Tutor
    vongehr
    "I am not aware of any principle of the conservation of information."

    It is the linearity (unitarity of the operators, e.g. scattering matrix) of quantum mechanics which conserves all the initial information.