Objective Collapse theories.

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Objective Collapse theories.

Postby hyksos on January 19th, 2018, 7:59 pm 

In the past few months, I have become a convert to Gravitational Objective Collapse.

In this thread, I will convince the reader to accept GOC and become a convert like myself. You may resist at first, but soon you will come to see the true power of the GOC Side.

GOC Highlights
  • Gravitational Objective Collapse is an interpretation of quantum mechanics.
  • Is not a 'hidden variable theory'.
  • (contra Many Worlds), requires only one universe, or one "reality".
  • Elegantly explains why macroscopic warm objects act according to classical physics.
  • Removes the act-of-observation (or 'measurement') from playing any causative role in wave collapse.
  • Makes testable predictions.
  • Boasts support by a variety of published physicists, including,

    Roger Penrose https://en.wikipedia.org/wiki/Roger_Penrose
    Nicolas Gisin https://en.wikipedia.org/wiki/Nicolas_Gisin
    Andor Frenkel https://www.researchgate.net/profile/Andor_Frenkel
  • Earliest inklings of GOC appeared in 1974.
  • GOC goes by different names in different contexts. Sometimes called either "Objective Reduction" , "Penrose Interpretation" , or the "Károlyházy Model of Quantum Mechanics"
  • Gives a physical relevance to the Planck Mass.


Further reading (off site)

Planck Mass https://en.wikipedia.org/wiki/Planck_mass

Gravitational Self-Energy https://en.wikipedia.org/wiki/Gravitati ... ing_energy

Penrose Interpretation https://en.wikipedia.org/wiki/Penrose_interpretation

chapters 29 and 30 in The Road to Reality. https://www.goodreads.com/book/show/106 ... to_Reality
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Re: Objective Collapse theories.

Postby hyksos on January 19th, 2018, 10:11 pm 

For busy people, GOC in two sentences or less :

Large, massive objects will decay quickly to a classical state. Very light objects -- fundamental particles, radioactive atoms -- take much longer to decay because they are extremely light (i.e. non-massive).

The details are more complicated than this reduced synopsis, and involve differences in quantum states expressed in gravitational self-energy. But the above at least conveys the basic gist.

Historical Context
For almost 30 years now, Max Tegmark has been going to physics symposiums at big-name universities, and asking for a show-of-hands for how many people in attendance adhere to interpretations of quantum mechanics.

In 1993, at Harvard, the vast 90% of hands went up for Copenhagen. Zero hands went up for Everettian Many Worlds.

In 2015, the crowds are more diverse, but some 60% or more of the hands go up for Many Worlds. Tegmark admits that this number has been slowly but steadily increasing at each seminar. Tegmark himself has been "turned" to the Many-Worlds Side of the Force. In his mind where there was once wobbliness, there is now resolve.

It should be noted that a few hands in the back row often go up in support of deBroglie-Bohm Guiding Wave theory. The Guiding Wavers (lets call them) are small-in-number but present at symposiums.

In the 2018, a rift has formed in quantum interpretations.
collapse_rift.png

The above diagram is by no means exhaustive or complete. But the outline of the basic bandwagons is apparent. There is a Collapse Bandwagon, and a No-Collapse Bandwagon. Today, you either find some kind of Collapse theory that you find compelling, because if you do not there is very little "elbow room" on the other side of the philosophical fence.

If you abandon collapse theories, you will mostly likely become seduced and get sucked down the river into the fashionable physics of Many Worlds. You will feel like one of the "cool kids" who is doing the "hot new thing" on campus. Either Many Worlds, or your choices are extremely limited. You may end up with a few nerds (in the back row of the symposium audience) who like Guiding Wave.

The diagram also shows an important grouping in that GOC is clustered into Collapse Theories. The binding motto among them is that the wave does actually collapse, and not "appear to collapse" to an observer in a particular branch of the multiverse, or due to some kind of information-theoretic hook involving Bayesian knowledge.

The diagram is lacking some other interpretations that exist outside of academia. Namely, I have left out "Consciousness of Observers Causes Collapse" and "Hidden Variable Theories". I made an executive decision as the author of this post to remove them, under the assumption that nobody on this forum is interested in either of them. (Perhaps I have assumed too much?)

The interested reader (who has freetime on her hands) can consult this article for an in-depth treatment of the context and history of Collapse Theories.

https://plato.stanford.edu/entries/qm-collapse/

The diagram lacks John Cramer's Transactional Interpretation. It was discarded because I do not personally understand it. There are other marginal interpretations having to do with something called Quantum Discord. Also left out because I do not understand it. Perhaps an excited advocate of those could visit this forum, and make a thread on them , as I have made a thread on GOC.

The psychological recoil from Many Worlds is certainly an impetus towards nudging a person towards GOC. We can present the decisive quandary thus : A coffee cup on a table is made out of quantum particles, but acts classically with extreme regularity. Why? The Many Worlders' answer to this puzzle is that the wave function never collapses, and there are several copies of the cup in several existing "realities", all equally real. We recall the cup in a particular configuration and position merely because that is the branch we rode through a multiverse.

One could flippantly dismiss such pondering if this were 1993. But this is 2018, and that exact sentiment is gaining adherents at a rapid pace in many university physics departments. Ignoring it is not going to make it go away. It is time to coral the wagons -- to set up a defensive barrier -- and to "put up or shut up" regarding quantum foundations. If a person does not take a stand now, their indecisiveness will only weaken their will when being seduced into the fire of a branching multiverse.

So join me in collapse theories. There are many surprises and "a-hah's!" to be found there.

This concludes my remarks about the context of GOC vis-a-vis the rest of physics. Now to turn to GOC in more detail.
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Re: Objective Collapse theories.

Postby hyksos on January 19th, 2018, 11:15 pm 

The first shot over the starboard bow is to get a bunch of bright teenagers in a room and ask them what the Planck Mass is. (take away their cellphones).

A bookish girl might suggest an answer that goes :

"The Planck Mass is the smallest amount of mass that can physically exist in the universe. It is therefore 1.47 times ten to the minus six . . ."


Stop right there.

The Planck Mass is 0.02 milligrams.

Yeah. Read that again. Take a deep breath and proceed after it sinks in.

There are literally things smaller than Planck Mass on the surface of your kitchen counter. Likely specks of salt and bacteria. The molecules of air in the room you are in are all -- everyone one of them -- much much smaller than the Planck Mass. (If your mind is not blown, it will be. Below. )

Imagine a world in which the common phrase "Quantum Mechanics" were instead replaced by the phrase "Sub-Planck Mass Physics". In every book and magazine article, replace one phrase for the other. In that alternative world, Max Tegmark would ask for a show of hands, and over 90% of the attendees hands would go up for GOC.

Because GOC , in a funny way, suggest that all these weird properties of quantum mechanics, the superposition, the entanglement, the teleportation of electrons, et cetera .... these are all properties exhibited by objects whose mass is less than the mp. And such weirdness is not seen in basketballs, cars, and the moon, because those objects contains mass far greater than mp

But Hyksos, this is silly. It would mean that atoms higher in the periodic table decay more readily than the lighter ones do and...

And what? That's exactly what is observed.

Hyksos, this is a fun idea to talk about over a beer, but no 'serious scientist' really gets into this kind of thinking because...

Sit down. I will now quote someone to assuage your doubts...

...I would like to suggest that it is possible that quantum mechanics fails at large distances and for large objects. Now, mind you, I do not say that quantum mechanics does fail at large distances, I only say that it is not inconsistent with what we know. If this failure is connected with gravity, we might speculatively expect this to happen such that GM2 / hc = 1 , or M near 10-5 gm ....If there was some mechanism by which phase evolution had a little bit of smearing in it, so it was not absolutely precise, then our amplitudes would become probabilities for very complex objects. But surely, if the phases did have this built in smearing, there might be some consequences to be associated with this smearing. If one such consequence were to be the existence of gravitation itself, then there would be no quantum theory of gravitation, which would be a terrifying idea...

Interesting little observation, dontchya think. The above was written by Richard Feynman, exactly three years before he was awarded the Nobel Prize in physics, in 1964.

Next.

No, my curious padawan. We're not done. Someone might complain that the aggregate mass alone cannot be the deciding factor, since you could spread apart an asteroid into constituent dust, dust so fine that we expect the particles to each exhibit a quantum behavior, yet could not since the "aggregate" mass is several tons of rock. The argument is sound. Something is missing in this GOC picture.

Technically, the mathematics of GOC depend not on aggregate mass, but rather on a quantity called the Gravitational Self-Energy. (wikipedia calls this "binding energy"). This is the requirement that our asteroid be considered an aggregate object, if and only if , its constituent rock pieces are densely packed together. In normal situations, the density of present matter is roughly on-the-order-of the same density. For familiar things like water, wood, glass, and some metals. Only in strange astronomical objects (like neutron stars) do you begin to deviate appreciably from this normal everyday density. The density itself can be ignored, and we can (approximately) express the Gravitational self-energy as scaling with raw mass.

GSE is expressed mathematically as a negative number, due to a convention with vector directions. (GSE starts at zero and 'grows' more negative). But generally speaking, GSE becomes 'larger' if the matter is more densely concentrated in space.

Matter compacted in the nucleus of an atom is a good example. We see between very heavy atoms of atomic number 109 and higher, atoms which remain stable for mere fractions of a second before decaying to something more stable. Because the nucleus is so incredibly dense, the mere addition of a single extra neutron can tip the balance towards varying atomic behaviors. Element 111 acts very differently than Element 112. Isotopes of Uranium are crucially different for similar reasons.

The decay of radioactive elements is the central, key metaphor for GOC theory. GOC does not suggest that basketballs are never in a superposition. It quite explicitly says that they definitely will be. (and so will cars and trees). Thing is, GOC demands that cars , trees, and basketballs "Decay" out of their superposition in timescales that are fractions of femtoseconds. On the lighter end of the spectrum, subatomic particles are so tiny, that they can remain in strange entangled and superposed states for minutes, hours, or years.

GOC proceeds by considering the gravitational self-energy of such large objects, and performing a calculation of their "half life" as if they were themselves nuclei.

In the next post, I follow the demonstration of Penrose, were we consider Schroedingers-Cat-like scenario involving a photomultiplier tube and an apparatus that moves a baseball.
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Re: Objective Collapse theories.

Postby ralfcis on January 20th, 2018, 12:36 am 

Super interesting but how is anyone on this forum going to understand it if it's not written in word salad? I have 1 objection:

"Removes the act-of-observation (or 'measurement') from playing any causative role in wave collapse."

I think there are examples of measurements not causing wave collapse and what is measured is the result of what the tool is designed to measure and there is no wave collapse.
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Re: Objective Collapse theories.

Postby hyksos on March 8th, 2018, 12:55 am 

Yet more evidence lending support to GOC.

Ethan Siegel writes an article about certain fundamental particles and their masses. In the article, Siegel demonstrates that the uncertainty in the particle's mass directly corresponds to the time it takes that particle to decay.

As a person who already adheres to GOC, I'm not the least bit surprised by anything in the article.

https://medium.com/starts-with-a-bang/in-a-quantum-universe-even-mass-is-uncertain-67d9adfd4940
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Re: Objective Collapse theories.

Postby DragonFly on July 14th, 2018, 6:26 pm 

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Re: Objective Collapse theories.

Postby Braininvat on July 14th, 2018, 6:58 pm 

DF, this link gives you 4 paragraphs then hits a paywall. Is there an article that doesn't require a subscription to New Scientist?
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Re: Objective Collapse theories.

Postby DragonFly on July 14th, 2018, 7:44 pm 

Braininvat » July 14th, 2018, 5:58 pm wrote:DF, this link gives you 4 paragraphs then hits a paywall. Is there an article that doesn't require a subscription to New Scientist?



Probably not, since the issue just came out. I read the print edition.

The time for the wave function of a piece of dust to collapse has gone down from 10**-18 seconds a couple of orders of magnitude from some falling test that LISA did, plus a European test (TEQ) that will take 3 years to build may get it down several more orders, and if it does then some better test will have to be built.

Some remaining "non thermal force noise of unknown origin" (Vinante & Bassi) that may 'ping' the collapse of macro size things was apparently identified when cooling something down toward absolute zero (cantilever test that reduced the estimate by more orders.)

Quantum Mechanics and String Theory will fall if objective collapse is true (returning realism), since they both take the current QM to be true (and in its anti-realism stance, which doesn't tell us what goes on); otherwise, if the collapse is due to gravity, with a threshold of one graviton, as Penrose is looking for, then they'd have to see how this comes out of Relativity. If neither, then new physics is needed. MAQRO is another experiment.

My own theory, which isn't anything, really, notes that a piece of dust is midway between the largest and the smallest, although I wouldn't know why exactly this would be important, but Penrose likes dust as a micro/macro target, too.
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Re: Objective Collapse theories.

Postby dandelion on October 26th, 2018, 3:21 pm 

Re the thread with the link leading here, I found this lighter but different account, too, but not sure to suggest it might be interesting here or there- https://www.quantamagazine.org/physicis ... -20180306/ . I think I'd missed this thread previously, but guess my guess of objective collapse was ok. I haven't read much on it. Incidentally, on the note of guessing initials from contexts, we've discussed ccc quite recently, but there was a different ccc by Penrose once that referred to something else. Looking for this link I happened on Motl's site and given some previous comments about that will warn objective collapse by Penrose doesn't escape a harsh attitude to much non-stringy there.
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Re: Objective Collapse theories.

Postby hyksos on October 29th, 2018, 6:57 am 

dandelion » October 26th, 2018, 11:21 pm wrote:Re the thread with the link leading here, I found this lighter but different account, too, but not sure to suggest it might be interesting here or there- https://www.quantamagazine.org/physicis ... -20180306/ . I think I'd missed this thread previously, but guess my guess of objective collapse was ok. I haven't read much on it. Incidentally, on the note of guessing initials from contexts, we've discussed ccc quite recently, but there was a different ccc by Penrose once that referred to something else. Looking for this link I happened on Motl's site and given some previous comments about that will warn objective collapse by Penrose doesn't escape a harsh attitude to much non-stringy there.

Penrose walks the same halls of Oxford that contained Stephen Hawking's office. Penrose, Hawking, and surrounding colleagues worked in a physics tradition called Semiclassical Gravity. The article linked above mentions Lajos Diosi. In that tradition, gravity is vehemently not quantum.

In String Theory (Motl's tradition) gravity is resolutely quantum.

Wolchover's article describes a microdiamond experiment at Warwick that would hope to show that gravitational interaction between two diamonds maintains entanglement. The results of that experiment would falsify G-O-C in a loud and conclusive way. While Penrose himself should find this experiment to be very crucial, Susskind's reaction to it is lukewarm. He is so comfortable with String Theory being correct, that he seemingly has no strong emotional reaction to having to confirm quantum gravity in a lab.

I quoted Feynman above. Notice the part where he says that if there is no theory of quantum gravitation, that he would find that "terrifying". I am just pointing that out. I literally don't know what Feynman meant by it being "terrifying".

In the meanwhile, I am going to obtain the July 2018 issue of Scientific American (from a library). I will be reporting back to this forum about the contents of the cover story. There were some recent Letters-to-the-Editor that referenced that article. At that time, I will describe why all of this stuff caught my attention.

E5FBDDF8-1250-4660-A04A4020AE827257_source.jpg
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Re: Objective Collapse theories.

Postby Braininvat on October 29th, 2018, 10:02 am 

You can also find out if cats are smarter, a theory my cat has been pushing for years. Coincidentally, I just checked out the issue from the PL, so will try to get to it this week.
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