Talk:Universal wavefunction

message: I don't know what Ray Streater's exact rationale is for his criticism, but to me the universal wavefunction is meaningless because it purports to say something about the totality of existence, which is a concept that abuses the logic of universal quantification. I do think Everett's relative state idea is brilliant though. It handles the Wigner's friend gedankenexperiment in a very elegant way. But extending the wavefunction to include everything is asking for trouble. To paraphrase Streater: What is the universal wavefunction a function of? --Shastra 11:14, 22 August 2006 (UTC)
replies: text: Denying the existing of a universal wavefunction makes as much sense (to me) as denying the existence of a classical universe.  The universal wavefunction is a function of the same things as other wavefunctions are.  --Michael C. Price talk 11:57, 22 August 2006 (UTC)
replies: text: Even classical universes can run into problems if we aren't careful about unobservable entities and infinities... Examples of ordinary wavefunctions are functions on Fock spaces that describe the quantum fields that have been observed in our universe. In the many-worlds picture that last phrase should be translated into: the quantum fields that have been observed in our current branch of the many-worlds. Is the universal wavefunction also limited to these Fock spaces? If that is the case, then (to paraphrase Everett) why draw the line there? --Shastra 15:44, 22 August 2006 (UTC)
replies: text: Obviously we can only describe the operation of that part of the wavefunction we know about -- again, the same situation that existed with classical physics.  Broader speculations are outside the scope of many-worlds and the universal wavefunction, with its extended Fock spaces or whatever emerges from a TOE, but may be discussed within the arena of the Multiverse (science).  --Michael C. Price talk 17:47, 22 August 2006 (UTC)

text: Specifically, the wavefunction is a function of the positions of all fundamental particles - a space with a dimensionality of 3n where n is the number of particles.  The mathematics are quite clear on this; there isn't any mysticism here. Warren Dew (talk) 03:37, 17 January 2010 (UTC)

text: Isn´t this pantheistic math on infinity and totally useless? While science often reject illogicalness, they accept pantheism, such as in hinduism with all its idols? Which probably stems from Tengri, the worlds maddest idol, a provokation and innovation against the real deity, that claims amanita legal and "the deity is all". Also known as the Tor of Vikings.  — Preceding unsigned comment added by Devote9000 (talk • contribs) 14:51, 13 July 2023 (UTC)
thread_title: Criticism

message: Be weary of the below comments, for I am certainly not a physicist.  The key thrust of all of the below is the apparent lack of mathematical details governing the Universal Wavefunction together with the Axiomatic basis underlying the Universal Wavefunction on this Wikipedia page.    
It would be good to understand what likely Mathematical Formalism (or axiomatic assumptions) are associated with the idea of the "Universal Wavefunction".  Such ideas would only be tentative dependent upon our knowledge.  The following are some points, typed out without any particular ordering principle: 
1) In simple systems, the Wavefunction has to be defined in relation to some co-ordinate system (ie: Psi=Psi(x,t)).  This assumes that we can use the co-ordinate system in a manner which specifies spatial and temporal locations in spacetime (not ignoring the detail that some would argue that we can only construct such a co-ordinate system if we are predetermined to do so in a deterministic system - however, it may be good to ignore this viewpoint in practice).  Some would argue that having an "in-principle" co-ordinate system is not sufficient for specifying the wavefunction.  We must actually construct (physically) such a co-ordinate system - however, this is just a "Philosophical" viewpoint.  
2) The Type of Partial Differential Operator that Constrains the Temporal Evolution of the Wavefunction or determines how the Universal Wavefunction will evolve with time.  Clearly, we should be aware of the Schrödinger equation and the fact that this is a Partial differential equation which relates the rate of change of the Wavefunction (a notion which most people conceive of in terms of real variables, but which could potentially find its "correct" description in terms of the Heim theory difference equation description - though how such a difference equation that governs the Universal Wavefunction emerges from the physical substrate of reality is something I would not say I have the answer to) to the Hamiltonian operator or a 'Laplacian plus Potential-Translation'.  The point would be that (dependent upon whether the deterministic state of affairs allows the experimenter to do so), we should be able to use such 'knowledge' to predict the behaviour of quantum systems *to an extent* (at the very least, we ought to be able to determine how quantum systems are NOT going to behave by ruling out what the Equation governing the Universal Wavefunction is NOT).  
3) The issues in (2) relate to the precise form of the equation governing Universal Wavefunction.  There are two forms to the Schrodinger Wavefunction According to the Wikipedia Page Schrodinger Equation - A Time Dependent equation and a Time Independent Equation.  From our perspective, the Time Dependent Equation seems to be in operation - Whether there is a perspective (co-ordinate system, whatever words you choose to use) from which the Time Independent Equation holds for the Universal Wavefunction is worth considering.  
4) Non-local hidden variables and their importance to the Universal Wavefunction.  There are deterministic interpretations of Quantum Mechanics (which may or may not be true, dependent upon your viewpoint), including the De Broglie-Bohm Pilotwave viewpoint.  How such a theory impacts upon the above points I would not wish to conjecture at this time.  I observe that, according to some sources which I can't currently find on the internet, the number of nonlocal hidden variables that could be associated with a given Quantum state (assumed to be the Quantum state of a system at a particular moment in time) could be more than one.  This might mean that there is more information within a Quantum system than we could ever find out from physical interaction with the system.  There are potentially other oddities concerning the Nature of Non-local hidden variables - but I would need time to consider these.  The fact that we have to deal with a configuration space of dimension 3n, where n is the number of "particles" (which could be very large) would likely make computational modelling based upon this theory highly expensive, or impractical.  So the natural question arises as to whether this theory has any practical utility beyond philosophical mumbo-jumbo.  This is a question I cannot answer.  
  
5) i) The equation governing the Universal Wavefunction has already been stated as possibly not being a Differential Equation but rather a Difference equation (possibly as per Heim theory - but who knows?).  This is just conjectural, and the precise details of this would likely be difficult to do Mathematically.  
ii) It may turn out that an alternative formulation of the De Broglie Bohm theory ought to use difference equations as well.
   
6) The use of Difference equations would SEEM to presuppose that reality is quantised in some sense.  However, that seems to me to be experimentally feasible (as per the Heisenberg Uncertainty Principle) but not absolutely clear - for instance, there is the Weyl Tiling conjecture (and the isotropy of space) which would appear to be difficult to reconcile with quantised views of reality (there's a paper out there entitled "Turning Weyl’s tile argument into a no-go theorem" which is worth a look - it states that "The continuum limit of a periodic graph, as experienced by a classical point particle, cannot be isotropic").  These views together would strongly seem to indicate the need for some "new" Mathematics UNLESS I have missed something more obvious.   
 
7) Not sure how String Theory or M-Theory fits into all this.  
I hope I have not broken Wikipedia rules by making the above points - though the overall assertion that the likely Mathematics of the Equation governing the Universal wavefunction should at least be eluded to or mentioned within the Article still stands.  
ASavantDude (talk) 13:59, 10 May 2018 (UTC)
thread_title: Some Mathematical Linguistics Carrying on from Above Discussion - Potentially Nonsensical Observations

message: Why not be consistent in the spelling and change the title to "Universal wave function" (not "Universal wavefunction")?
--Mortense (talk) 14:39, 20 June 2021 (UTC)
thread_title:  Consistent spelling 

message: It's correctly called a dissertation, isn't it, not a "thesis." The dissertation was titled "On the foundations of quantum mechanics." The other title you refer to was a separate document Everett wrote that appeared in a publication published by Bryce DeWitt. That's the information I have. I could be wrong. I don't think so. 2600:8801:BE31:D300:35FC:30A7:384F:12D5 (talk) 03:43, 26 July 2022 (UTC)
thread_title:  You have the wrong title to Everett's PhD dissertation, don't you?