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The End of Physics and Failure to Integrate QM & Relativity

  1. Jan 8, 2012 #1
    I'm not posing this to be a forum troll or to insult the excellent ongoing work in Physics.

    It's a serious question based on the following:

    * Most of relativity and QM theory was completed within 20 years by a few dozen
    scientists.

    * Their tools were very primitive-not even electric calculators.

    *Experimental evidence was very thin at the best of times.

    The failure to integrate QM and Relativity over more than 60 years with the huge
    numbers of scientists since then and their resources is very significant

    What can be concluded?

    1. The problem is FAR more difficult than the derivation of newtonian physics or QM or
    relativity alone?

    2. It requires an Einstein or Newton with the insight to create an entirely new physics?

    3. One or more of our fundamental assumptions must be in error and that is what prevents
    unification?

    One could argue that IF physics is a complex jigsaw puzzle supported by math, then the
    puzzle should be easier as more pieces are filled in- just as any logical framework should. This does not seem to be happening.

    Or one could argue that this process is not linear but is in fact discontinuous- operating
    in leaps and bursts of findings once an essential conceptual breakthrough is achieved.

    Again, no disservice to the troops of physics but the last 60 years suggest a fundamental
    failure in the architecture of physics that doesn't seem even close to being resolved.

    Appreciate any comments and discussion.
     
  2. jcsd
  3. Jan 9, 2012 #2

    tom.stoer

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    I think you miss something here:

    1) after the success of QM decades of hard work regarding QFTs for el.-mag., strong and weak interactions were necessary
    2) QG is a difficult enterprise as there are purely theoretical indications but no experimental guideline; the QG regime is not testable with currently available technology
    3) there are several promising attempts how to quantize gravity (strings, loops, ...)
     
    Last edited: Jan 9, 2012
  4. Jan 9, 2012 #3

    Ken G

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    Also, great theories are often created "within 20 years" of the big idea that got them started, or the big experiment that pointed to their need-- not within 20 years from the previous theory. We should probably start the clock with Newton by the late 1600s, so it actually took about a quarter of a century to get QM and GR. It will certainly take physicists of the character of Newton and Einstein, but they come along not so infrequently-- the most important thing, I believe, is the surprising observational result that creates the "seed change" needed. But it's hard to know when that will come along-- it could be a century, or a decade, or maybe it has already happened but its significance has not yet been recognized. Meanwhile, the groundwork keeps being laid, perhaps in the mathematics surrounding string theory.

    Of course, we must always also keep open the possibility that the next great breakthrough in physics will not unify QM and GR, but simply chuck out both of them. That might take a bit longer! Or it might be in a completely new direction, like understanding of the role of the mind in doing physics. That might take longer still! My guess is that we have much farther to go in our journey than we realize, but that would be nothing new.
     
  5. Jan 9, 2012 #4

    tom.stoer

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    One thing should be clear: b/c experimental guidelines are largely missing in constructing a theory for QG, there might be a kind of paradigm shift, i.e. a much stronger focus on mathematical rigour and 'physical reasoning'. Comparing that to the development of QM and GR it's more like constructing GR (all experiments but perihelion precission came later) than QM (many results on atomic spectra were already available).
     
  6. Jan 9, 2012 #5
    I completely agree that there is a big problem in the failure to integrate QM and Relativity but I see this as the beginning of physics not the end. The starting point as I see it is to resolve the interpretation of QM and find the correct description of reality. The debates in other threads highlight the lack of consensus on the interpretation of QM. Roger Penrose wrote an excellent book of over 1000 pages "The Road to Reality" which states the problem.

    We have an excellent set of mathematical equations in QM providing very accurate results but the top level description of what is going on is missing. Once we get this right, I think we will have a road map to resolving the physics of the very large and the very small.

    We have to first answer questions such as:
    How does light propagate through space?
    Why is light wave energy subject to quantum constraints?
    What gives rise to the property mass?
    What is the fundamental nature of matter?

    WaveHarmony
     
  7. Jan 9, 2012 #6
    If we take into account gravity in solving the Schrodinger's equation for the evolution of a particular microscopic particle, will it just give us the same answers as if we didn't take into gravity and solved the equation?

    By combining relativity and QM, for gravity to 'collapse the wave function', would the Schrodinger equation need to be modified? Or will gravity give one particular state with probability 1 if we continued to use the Schrodinger equation?
     
  8. Jan 9, 2012 #7

    kith

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    Yes. In the simplest scheme, you simply add an interaction between the wavefunction and the Newtonian gravitational potential. See http://en.wikipedia.org/wiki/Penrose_interpretation
     
  9. Jan 10, 2012 #8

    tom.stoer

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    No, not necessarily.

    There are several QG approaches (strings, LQG, AS, ...) which do harmonize quantum field theory and gravity to a certain extent w/o modifying the basic rules of quantum mechanics, especially linear operators on Hilbert space plus superposition principle. Of course these approaches do not say anything regarding "collaps of the wave function" but as far as I can see this "Kopenhagen - collaps interpretation" is no longer the favoured interpretation anyway.
     
  10. Jan 10, 2012 #9

    cgk

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    The failure of integrating QM and *general* relativity should mainly tell you that there is little practical need to do so. You also need to realize that >99% of physicists work in areas completely unrelated to this topic.

    Is physics at an end? That's a silly question considering the device you have been typing this on.
     
  11. Jan 10, 2012 #10

    tom.stoer

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    We know that there are severe inconsistencies in straighforward application of standard methods of QFT in the context of GR. We know that GR predicts its own breakdown at singularities which are unavoidable due to singularity theorems by Hawking & Penrose. This means that harmonizing QFT and GR is more a conceptual than a practical issue.

    This is like saying that there was no need for Einstein to develop GR b/c most physicists are not working on cosmology.
     
  12. Jan 10, 2012 #11

    cgk

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    Yes. And this is true for 99% of physics. There are *very* few physical problems which involve graviation at a level which cannot be described by Newtonian physics, and of the remaining ones all of technical importance (I think there was one more than GPS, wasn't there?) can be handled at the weak-field expansion level. So if general relativity had never been developed, the state of the physical science as a whole would like not look terribly different than it does now. In fact, it might be much more advanced, because less of the most clever people might have spent so much time on trying to unify QFT and GR and have rather gone for more real-worldy problems.

    Nevertheless, the difference between "developing GR" and "developing the unification of QFT and GR" is that the former *does* have implications, while for the latter this is questionable.

    My main point is simply that interpreting the failure to unify QFT and GR as a serious problem of the state of physics as a whole is *GROSSLY* misrepresenting what physicists actually do. There are *tons* of impressive advances in physics, and we can see them, very obviously, in everyday life.
     
  13. Jan 10, 2012 #12

    Ken G

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    I think that's a valid point, but there doesn't have to be disagreement. Physics is both-- it is the everyday stuff that makes life better (if it doesn't blow us up, or warm our planet, the usual cautions), and it is also the magnificent understanding of our reality that we can achieve by it. The latter is certainly more aesthetic, but also more grandiose. Do we remember the Egyptians for how they advanced written language, or for the pyramids? This kind of debate applies also to the effort to get to the Moon.
     
  14. Jan 10, 2012 #13
    So really those candidates for Quantum Gravity don't predict a collapse of the wave function.
     
  15. Jan 10, 2012 #14

    tom.stoer

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    They neither predict it, nor do they rely on it or talk about it.
     
  16. Jan 10, 2012 #15
    Sounds interesting, hollowsolid. If integrating two theories is so complex I agree that it is a valid option to consider that there is a fundamental misunderstanding in one of the theories.
     
  17. Jan 10, 2012 #16
    Sorry to disappoint you, but money and brains and hard work just aren't everything. People have been complaining about this for eons and you'd think the universe would always reward such things and reward them promptly, but that's just not turned out to be the case. Sometimes its quite embarrassing even. For example, Aristotelian physics was showered with all the money, brains, and hard work available for hundreds of years only to be slapped in the face by reality when some radical upstart began throwing toys off the top of buildings. Its enough to make one loose their faith in the power of ego.
     
    Last edited: Jan 10, 2012
  18. Jan 10, 2012 #17

    cgk

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    Of course you are completely right about that; I'm certainly exaggerating this practicality issue. I just object to the all-too-common misconception that physics is all about dark matter and loop quantum gravity. Deep understanding does not only come from the most fundamental laws in nature; in fact, all the approximate laws are perfectly fine in their respective domain of applicability, and these are usually known. Additionally, to see why little would be gained if a kind of "world formula" was ever found (and its range of validity experimentally validated!), I urge everyone to read
    PW Anderson - More is different
    (http://www.tkm.kit.edu/downloads/TKM1_2011_more_is_different_PWA.pdf).

    Even if one cares only about deep understanding, physics is at least as much the Scanning Electron Microscope (SEM) or the transistor as it is Quantum Field Theory. The former may well be the single most versatile and powerful instrument physics has ever created, and its role was essential in fundamental discoveries beyond count. So when you say "physics", why do people think "string theory"?

    [1] Incidently, both theories with poor experimental support and which as a layperson one likely could not even understand *if* a consensus was ever reached about them.
     
  19. Jan 11, 2012 #18
    While it's true that the foot soldiers of science are often overlooked I still don't believe we can ever underestimate the significance of radical breakthroughs in theory- here I mean
    those that totally redefine what we are as physical objects, apparently conscious observers
    and complex biological systems.

    For me having an LCD vs a black n white tube is nowhere near as important as knowing the
    fundamental objects manipulated in them such as electrons are quantum and as such have properties that are dependent upon what is inquired by the observer a la the double slit
    experiment.

    For me that experiment simply redefines what existence is- compared to what i thought it was.

    Yes it's nice to have an MRI to fix our cancers but for me it's even more important to
    know that earth is not the centre of all creation, or even our solar system and certainly not
    our universe. It's crucial to know that I am an outcome of simple rules applied in a biological
    domain over millions of years and in the process I am an essential part of the universe-
    no less than the trees and the stars- and not the favourite breed of a supreme imaginary
    person.

    Thanks to relativity and QM every common concept of mass, space, energy and time have
    been blown away. The football games go on regardless and the latest fashion sensation
    cares not a whit, but that has always been the same.

    Some people help redefine what existence actually is and what it means to be human. The fact that this does
    not penetrate the masses and their focus on the trivial (as well as their appreciation of
    new technologies) does not make it any less crucial.

    The purpose of my original post was not to diminish the contribution of the bulk of
    physicists but to comment on the seriousness of our inability to integrate the physics of
    the very small with the physics of the very large.

    Given that these laws operate in the same universe then this is quite alarming.

    Moreover many theories in physics can be derived from each other and show
    their integration into an overall architecture of theory. In contrast much of QFT is
    problematic and integrating gravity within QM leads to infinities that spawn yet more
    intellectual gyrations to make them disappear.

    The fact that this has been going on since the 30s is very disturbing. I don't believe that the
    small group of Bohr, Born, Schrodinger, Heisenberg etc were more talented than a couple
    of generations of physicists since. Yet that group took QM by the throat in basically
    10-15 years--- in an age of postal communications without so much as a desk top calculator.

    We have billion dollar accelerators and more PhDs who understand advanced physics
    than the pre-war theorists could ever dream of.

    Yes huge advances have been made but the intractability of the problem seems to be
    in sharp contrast to the rapid advances that happened in the first few decades of the
    last century.

    Maybe it does take a unique individual to create the conceptual breakthrough that
    allows the rest to go out and explore the new territory. Somebody has to see the new
    territory first.

    Personally I always thought it amazing that it was Einstein who defined the quantum
    via the photoelectric effect and set the stage for SR- although a few others were
    close on his heels. But as for GR, no-one was even in the ballpark with him when
    he finished this work.

    Maybe that's what we need once again. Although i recognise of course Einstein's
    disagreement with the whole quantum enterprise.
     
  20. Jan 11, 2012 #19

    ZapperZ

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    Closed, pending moderation.

    Just because this thread is in GD does NOT allow it to violate the PF Rules.

    Zz.
     
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