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BM is incompatible with MUH

  1. Dec 24, 2009 #1
    Tonight I’ve realized that BM has some philosophical issues. It appears that I did not find anything really new, but it is interesting for me to discuss some details, especially BM vs MUH (Mathematical Universe Hypotesis (c) MaxTegmark) and consciousness

    I started to think about the ‘dead’ branches where wavefunction is ‘empty’, and I realized that there is an additional axiom in BM; axiom so obvious that nobody is talking about it explicitly. BM does not only postulates the existence of ‘particles’, guided by the wavefunction, but it also claims that ‘only non-empty branches are real’

    From that moment there is a total mess.

    1. In BM wavefunction is objective (does it means that it is real?) So there are 2 types of the math in BM: those describing the “particles”, and those describing waves. In other words, those describing what is real and those describing what is not real (?). In that case, BM is inconsistent with MUH, because it claims that some formulas (the ones which describe the particles) are “REAL” (whatever it means) while others are not No matter what TOE formulas will be, there will be unavoidable “word baggage” left: on the T-shirt with formulas of TOE there will be a big arrow pointing to some of them with a big red capital “REAL” on it.

    2. What is a difference between an empty and real branch of conscious being? Except the hidden particles nobody can observe, the wavefunction is the same. The unavoidable conclusion is that it is an existence of the particles which is giving the system it’s consciousness Except for the particles, the brain wavefunction in empty branch is the a wavefunction of a normally functioning brain – and yet it is not conscious! This is a perfect example of P-zombie (wiki it)

    3. is REAL=OBJECTIVE? Or does BM provide an example of what is objective, but not real? Are empty branches real? If they are not, why the wavefunction is called ‘objective’? If wavefunction is real (“Both Hugh Everett III and Bohm treated the wavefunction as a physically real field” (c)) – then why brain is not conscious without particles inside?

    4. Do Bohmians agree with this (especially with the bold):

    According to some authors, if the (never collapsing) wave function is taken to be physically real, then it is natural to interpret the theory as having the same many worlds as Everett's theory. In the Everettian view the role of the Bohm particle is to act as a "pointer", tagging, or selecting, just one branch of the universal wavefunction (the assumption that this branch indicates which wave packet determines the observed result of a given experiment is called the "result assumption"[18]); the other branches are designated "empty" and implicitly assumed by Bohm to be devoid of conscious observers David Deutsch has expressed the same point more "acerbically” : “pilot-wave theories are parallel-universe theories in a state of chronic denial.[22]
  2. jcsd
  3. Dec 25, 2009 #2


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    No theory in physics, not even MWI, is compatible with MUH. BM is not an exception.

    For example, think about the Hamiltonian in classical mechanics. Is it real? Is it objective? Wave function in BM is very similar.
  4. Dec 25, 2009 #3
    1. Why MWI is not compatible with MUH?
    2. So why brain made of empty wavefunctions ios not conscious in BM?
    3. Wiki claims that in BM wavefunction is 'objective'. Do you agree?
  5. Dec 26, 2009 #4


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    1. According to MUH, any mathematical structure is real. According to MWI, only a solution of the Schrodinger equation is real.
    2. I know nothing about the physical origin of consciousness. Do you?
    3. Yes.
  6. Dec 26, 2009 #5
    1. MWI is just a special case: Schrodinger equation forms one of the universes. So MWI does not deny MUH

    2. No. But doesnt BM claim that brains made of empty waves are unconscious? Or it claims that they are not real? What is that BM axiom is saying exactly?

    3. Ok. Then brains made of empty wavefunctions are objective, but not real? or objective, but not conscious?
  7. Dec 26, 2009 #6
    2. You've read Douglas Hofstadter, right?
    Last edited: Dec 26, 2009
  8. Dec 27, 2009 #7
    No. Shame on me. Do you recommend his book?
  9. Dec 27, 2009 #8
  10. Dec 27, 2009 #9


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    1. In that sense BM does not deny MUH either. BM is a mathematical structure itself, which also forms one of the ˝universes˝.

    2. It says that a brain made of particles does not exist in empty waves.

    3. According to BM, a brain cannot be made of wave functions, just as it cannot be made of Hamiltonians. (Hamiltonians are also mathematical structures, right?)
  11. Dec 28, 2009 #10
    1. ... to be continued after you reply to #2

    2. So it is "objective" but "does not exist"?
    And WHY it does not exist? Is there an axiom about it?
    Could you provide the text of that axiom?

    3. Yes, because the particles are needed.
    Again, could you provide the text of that axiom?
  12. Dec 28, 2009 #11


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    You ask difficult philosophical questions that I am not able to answer. It is not the goal of BM to answer such questions. The goal of BM is to reduce quantum theory to a theory in which all philosophical questions are analogous to similar philosophical questions in classical mechanics. Since philosophical questions in classical mechanics are generally viewed as much less important than those in standard quantum mechanics, BM reduces more important philosophical questions to less important ones. It is certainly a step forward, but you have right to not be satisfied with it.
  13. Dec 28, 2009 #12
    Thank you for your reply
    I would say, BM also have some deep issue like MWI.

    MWI can not explain Born rule
    BM has issues with 'objective', 'real' and 'exists'
  14. Dec 29, 2009 #13


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    Dmitry, what would you say about the Hamiltonian in MWI? Is it objective? Is it real? Do you think that MWI (not MUH, but just standard MWI) has a clear answer to such questions?
  15. Dec 29, 2009 #14
    Yes, omnium is objective and real and it exists (and is described mathematically).
    Based on MUH: objective=real=exists=described mathematically

    MWI alone is based on the minimalistic approach, so it does not claim that other worlds exists, but it can not deny their existence (as we observe at least one)

    Note that the MWI issue with the Born rule has the same nature the BM issue with the existence. In MWI there is "measure of existence" described by the omnium. In BM "measure of existence" is either 0 or 1, and is correlated statistically to the wavefunction.

    I dont understand, however, how BM explains that empty waves are not 'real'. If it is an axiom, then it can not be described mathematically. It is just a marker, highlighting some formulas (these formulas describe what is real). If it is derived somehow from the BM itself, then the conclusion that particles create the consciousness is unavoidable.

    The issue is not adressed in the descriptions of BM I know. The issue itself is so natural to our "common sense reasoning" that is skipped by our mind. But you remember what happened to the "naive set theory"?
  16. Jan 9, 2010 #15

    Hi Dmitry,

    I highly recommend this paper by Valentini which addresses your questions:

    De Broglie-Bohm Pilot-Wave Theory: Many Worlds in Denial?
    Authors: Antony Valentini
    To appear in: 'Everett and his Critics', eds. S. W. Saunders et al. (Oxford University Press, 2009)

  17. Jan 9, 2010 #16
    Thank you, will read
  18. Jan 10, 2010 #17
    While this article answers 1 question - wavefunction is interpreted as 'real' in BM, it does not answer other questions. Well, it tries using a lot of handwaving, using what Max Tegmark 'the baggage'. All that wordy stuff serves a single purpose: explain gthat empty waves are somehow 'less the real'.

    The most interesting part is at pp 16-17, but the logic there is circular. I can elaborate if this subject in interesting.
  19. Jan 12, 2010 #18
    I have another idea. In BM there is only 1 type of particles. Such particles mark some waves as 'tagged', while empty waves are 'non-tagged'. Tagged branches are called 'real' (this is an axiom which can not be in principle described in mathematical terms)

    Now imagine that there are 2 types of Bohmian particles: type I and type II. They dont interact. Now we have non-tagged branches, tag-I branches and tag-II branches.

    Now what is real and what is not real?
    You say, use Ocamm to get rid of type-II? Well, Ocamm also cuts type-I, so, if type-I is accepted (for me Ocamm is not absolute, and for Bohmians it is not absolute too of course) then Ocamm can't be used to deny the existence of type-II particles.

    It creates an infinity of BM-(N) theories whit N different classes of particles. N=1 must be also an axiom ( mathematical one) but I dont know how it can be justified. if N>1 then the meaning of 'what is real' becomes even fuzzier then before.
  20. Jan 13, 2010 #19


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    It can be justified by Ockham.
    You will say that Ockham predicts N=0. However, N=0, which corresponds to pure MWI, cannot explain the Born rule. N=1 is minimal N compatible with the Born rule.
  21. Jan 13, 2010 #20
    Well, BM 'explains' the Born rule at a cost of a 'hidden' axiom (tagged is real). As soon as you accept it you can infact derive the probability for tagged observer to see the tagged outcome. With the same success I could add Born rule (or a weak form of it) to MWI saying that now it 'explains' the Born rule. But I think it would be interesting to try to avoid doing it.

    But I am happy that I had actually found an example of 'physical' axiom which can not be exmplained in form of equations. Long time ago, discussing MUH, I asked if anyone coudl provide any examples, and there were none.
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