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Time noninvariance in quantum physics

  1. Feb 18, 2010 #1
    The discussion about the existence and importance of experimental study of the strong time noninvariance in quantum physics lasts more than 10 years (see arXiv:hep-ph/0002084, physics/0612089v2 and others). Its essence is that the inequality of forward and reversed processes is quite usual in the quantum physics. As a fact it is a real physical base of most phenomena in nonlinear optics. The situation is quite similar to those when we do not see a forest behind the trees.

    However, this is an unusual discussion: it has one-sided character. The theorists are silent as a fish, and the experimentalists are afraid of working in this direction without the theorist's approval. As a result the quantum physics stagnates: instead of studying a physical mechanism of phenomena, the scientists study its abstract mathematical models. The reason of such sabotage is not clear for me, but some sense exists that it is located outside of the physics.

    There are absent any objective obstacles for experimental study of time noninvariance in quantum physics. I am sure that it will be quick and widespread experimental study, but we need now in some outside push, which can move the situation from the dead point. The nature of this push and who can make it are also not clear. So, I'd like to know the opinions of or advices from the participants of the forum about the discussed situation (please, send your comments after the examination with the subject of discussion).
  2. jcsd
  3. Feb 21, 2010 #2
    It seems like you are referring to the appearance of the arrow of time. There is a lot of discussion about this, actually. Considerations of open systems seem to lead naturally to an arrow of time. Open-system methods are used very commonly in quantum optics and they successfully describe experiments that exhibit an arrow of time. Even spontaneous emission can be understood in terms of an open systems description.

    Can you clarify in what way these descriptions are deficient?
  4. Feb 24, 2010 #3
    I am not sure that I correctly understand your question. I am not a theorist and I nothing know about the open systems description.

    The conclusion about time asymmetry in microworld directly arises from the experimental results. Of course, it in a natural way supports the idea of the arrow of time in macroworld.

    A number of descriptions of a nature can exist now. However, the nature is only one and in a future only one most correct description should remain. I do not know what description of the arrow of time will remain. For example, the Newton’s lows in the classical physics exist. It seems nobody proposes now alternative descriptions there.
  5. Mar 2, 2010 #4
    Open systems quantum mechanics shows that time asymmetries can arise from time reversible interactions when we only have access to incomplete information. Almost any modern text on quantum optics will discuss these ideas.
  6. Mar 5, 2010 #5
    Well, I understand the question.

    It is quite probable that you can explain the arrow of time in open systems quantum mechanics with time reversible interactions, but in any case this is insufficient explanation, because of the second law of thermodynamics clearly points out that the arrow of time should exists also in a closed systems (see, for example, arXiv:1002.0314).

    The main obstacle on the way of physical explanation of the origin of the arrow of time is the common opinion that “the laws of physics are invariant under time reversal”. You can see this expression in many articles. But I never saw any arguments behind these words. This is an axiom. And this is a great error.

    So, my advice is: if you will meet a person, who will say you that the laws in quantum physics are time reversal invariant – spit in his face: he deceives you :-).

    Time reversal invariance is not a property of the laws in quantum physics. More probably this is a property of the mathematical models, which describe the phenomena in the field of quantum physics.

    The experimental proofs (direct and indirect) lie on a surface and everywhere. In Russian rather exact expression exists for this case (разуть глаза): let us take shoes off the eyes. But the people do not want to see this proofs. My attempts to put their attention on this proofs give till now only opposite results: the scientists become to be afraid and sometimes interrupt to work in the discussed direction. As I understand, the experimentalists will begin to work only when their theorists will say them that this is right and it is worth to be studied.

    But the theorists are silent. The official answers on the comments are absent. The unofficial answer is that the mathematical models describe the observed phenomena in quantum physics (better or worse) and what else do you want?

    I believe that for the progress of the physics correct physical explanations of phenomena are much more important than their mathematical descriptions. The mathematics should play auxiliary and secondary role. I have great respect for mathematics. My wife is a mathematician (she is a teacher in a school :-). But for the present day in the field of quantum physics we have from the mathematics more damage than the profit.
  7. Mar 6, 2010 #6
    kvladimir -> It seems to me that you confusingly mix a lot of concepts that are really separate.

    Physics is invariant under time reversal. It's probably better that you do not spit in anyones face when they claim that, as nobody is deceiving anybody. Also, this debate has been going on for far more than 10 years. It's been discussed at least since the introduction of QM. This is an assumption about physical laws at the microscopic scale. And this fact is also given a theoretical formulation in terms of "time reversal invariant equations". Clearly, any assumption has to be tested and this one has been confirmed in the lab basically in every particle experiment that does not include CP (charge and parity) violation. And again, here I'm talking only about experiments where the particles are left to interact only amongst themselves. On the other hand, if you switch on, say, an external electric field which you have the possibility to control and hence make time asymmetric, than clearly the results will not be time reversal invariant. And this fact also has been both formulated theoretically and tested. But let me emphasize again that this is at the MICROSCOPIC level.

    On the other hand, it is clear to everyone that there is a time asymmetry in the MACROSCOPIC world, both for open and closed systems. (For a closed system, suffice to think of a box containing two gases separated by some wall which is then removed - the two will mix and the time symmetry is obviously broken.) So a natural question is then how does this time asymmetry arise if the underlying MICROSCOPIC laws are indeed time reversal symmetric? And this is essentially the arrow of time problem. And people have tried to give an answer to this problem, see e.g. http://arxiv.org/abs/0802.0438, but I'm not sure if any solution has been universally accepted yet. (The above paper ha been criticized as well.) But this is a different type of problem!

    Finally, the (established) mathematical models are nothing but the mathematical formulation of physical reality, or believed to be such as of today. And the current models have been verified experimentally over the past 80 years or so. But you can be sure that as soon as some experiment finds a contradiction with the mathematical models, it won't be the experiment that has to be changed, but the models. And the experimentalist, if the results will be confirmed by others, will fly to Oslo to collect her Nobel prize. And Here I want to emphasize if the results will be confirmed by others.
  8. Mar 10, 2010 #7
    You, probably, do not understand the sense of this thread. The problem to confirm the experimental results is absent. Other problem of correct interpretation of the existent experimental results takes place. The theorists so pull the wool over experimentalist’s eyes by their “established” mathematical models, that those for many years can not understand rather simple and direct physical sense of the existent experimental results.

    So, I can repeat. The existent experimental results clearly point out on a strong time asymmetry in interaction of photons with atoms or molecules: differential cross-sections of forward and reversed processes are not equal (in contrast to the common opinion and the “established” mathematical models). Your “established” mathematical model should be rejected, because of it contradicts to the physical laws. And you (theorists) should propose other “unestablished” mathematical model, which will correspond to the time asymmetry physical laws in quantum physics.

    The experimental proofs lie on a surface and practically everywhere. However, the experimentalists under action of hypnosis of the “established” mathematical models do not want to see it. I am ready to discuss the experimental results, facts, arguments in the fields of quantum physics, nonlinear optics, etc. But it is difficult to discuss the theorist’s emotions and imaginations.

    About spits … Sorry. Of course, there was only a joke. Do not worry. I am not ready to spit in the opponents (the saliva will be not enough :smile:).
  9. Mar 10, 2010 #8


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    Ok, it seems to me that you are not drawing the appropriate separation between time reversibility of physical *laws* and time reversibility of physical *phenomena*. Your examples so far describe observed time-irreversibility of physical *phenomena*. I would say that time irreversibility of physical *phenomena* can be consistent with more general physical laws that are time-reversible. What you then need is a physically consistent explanation of *how* the apparent time-irreversibility of the phenomena can be derived from the time-reversible laws. Decoherence is an example of such an explanation, which shows how microscopic entropy can cause a quantum state to evolve consistent with time-reversible laws in a fashion that is FAPP (for all practical purposes) irreversible. To me this has a beautiful symmetry with how time-irreversible phenomena on the macroscopic scale can also be explained in a clear way using entropy.

    It would help me to understand your point of view if you could elaborate on what you mean by, "The existent experimental results clearly point out on a strong time asymmetry in interaction of photons with atoms or molecules: differential cross-sections of forward and reversed processes are not equal." I read arXiv:hep-ph/0002084, but I could not access the aps-Eprint papers referenced therein to see the experimental details for myself. I am extremely interested in the "hole-burning" you describe, and I think I may have an idea about how it can be explained in terms of the vibrational dynamics of the excited molecules. However I need to understand the details of the experiments in order to proceed.
  10. Mar 10, 2010 #9
    SpectraCat -> Thanks for saving me some time and writing up what I had in mind about the distinction between laws and phenomena :) I would just add that it might happen that all one needs to do to account for the "time asymmetric" phenomena Kvladimir is talking about is the to write down an approriate model to describe it. A model that *explicitely* breaks time invariance. And then, as you pointed out, it sure is an interesting question to understand if and how could one derive such a model starting from time invariant first principles. Also looking forward to see if you could shed some light onto the experimental results Kvladimir is talking about.

    Kvladimir -> Even *assuming* you are correct about some fundamental flaw in the mathematical formulation of physics as it is known today, shouting out loud how obtuse the theoretical community is won't help much. Even more so when you insist in saying that experimentalists are basically sheep who won't test stuff that therists don't want them to. I'd say is actually the opposite - experimentalists are actually rather happy to prove that "the abstract nonsense" theorists talk about is wrong. Much like you want to, and I quote, "discuss the experimental results, facts" and not just nonsensical formulas. Save your saliva to discuss about science.
  11. Mar 10, 2010 #10


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    Welcome to PhysicsForums, Kvladimir!

    There is certainly a community of theorists looking at time invariance in QM. Specifically, there are interpretations such as Cramer's TI and also Relational BlockWorld (RBW) that postulate that the future can influence the past. So my question is: what are you trying to say about the subject? I can cite experiments in which the distinction between the past and the future is not evident, which would "tend" to support the idea of time symmetry.
  12. Mar 12, 2010 #11
    It is important for successful discussion to have a concerted meaning of terms. In opposite case a discussion may be endless and nonsensical. However, you had not defined how you understand the difference between “physical laws” and “physical phenomena”:smile:.

    But I keep in mind, obviously, just time asymmetric "physical law": when the differential cross-section of absorption of the photon by the atom is not equal to the differential cross-section of the following reversed process of stimulated emission of the photon by the same atom (in contrast to common for present day opinion). The main question here is the correct explanation of the existent experimental results. It may be explained as usually now in terms of decoherence (coherent states), entanglement, quantum interference and so on. And it may be more correctly (as I believe) explained on the base of time asymmetry of fundamental physical laws.

    The old aps-Eprint arXiv is closed now and those article is not remind. But most of that results were published later in arXiv:physics/0204003, 0207111. Unfortunately, the experiments in this field were interrupted nearly 20 years ago and this interesting object remain unexplored till now. This object – wide component of line in polyatomic molecules (or in other more early term the so-called “quasicontinuum”) has unique properties: extremely wide HOMOGENEOUS spectral width (150 GHz) corresponds to a long lifetime of excited states (ms). Just this properties allow easily to see strong inequality of forward and reversed transitions. Only after that I began to be interested in time noninvariance in physics.
  13. Mar 12, 2010 #12
    I understand already that I find myself in an anthill or better in a beehive of African bees :smile:. I am experimentalist and practically do not know the mathematics. So, we have quite different knowledge and mentality. Physics-theorists are historically known as great snobs. But I hope that your colleagues will take into account my defects and reveal some loyalty: the discussion will be not restricted only by curse and denomination of each other, but will also deal with the problem of time noninvariance in quantum physics.

    Such discussion is absent in the field of e-print arXiv. If you will publish a comment to any e-print and write that the authors incorrectly explain their experimental results, you may be sure that you will immediately obtain the adequate answer. For the number of my comments I had not obtained any official answer. I believe that this is because of the authors do not have sufficiently strong arguments.

    Your theorist community lives in your own abstract world. I would like to push a little this world toward the real physics. I believe that the quantum physics is based on the time-asymmetrical physical laws. We have for present day sufficient experimental proofs. The main problem is in its correct interpretation.
  14. Mar 12, 2010 #13


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    I'm puzzled. Is this time "non-invariance" similar to broken time-reversal symmetry that is very common in condensed matter system? If it is, then I don't get this claim that this is a "mystery" or that things are not well-known. One can easily do a search on such a phenomena and come up with tons of publications, both theoretical and experimental.

  15. Mar 17, 2010 #14
    In the condensed matter field a great number of publications about so-called spontaneous symmetry breaking (arXiv:cond-mat/0211110, physics/0609177) and broken time-reversal symmetry (arXiv:cond-mat/0203133) indeed exist. However, it has nothing common with the problem, which is discussed in this thread.

    I discuss the existence of strong time noninvariance in a microworld, namely in interaction of a photon with atoms and molecules. The common opinion exists here that the cross-sections of forward and reversed transitions are equal. However, this is only the assumption. In contrast, I prove that we have direct and indirect experimental proofs of strong inequality of differential cross-sections (although the integral cross-sections should be equal). And this time asymmetry in microworld is a physical base of most phenomena in nonlinear optics.

    So, I believe that time noninvariance in optics is much more important and interesting problem, than the discussed spontaneous symmetry breaking and broken time-reversal symmetry in condensed matter system.
  16. Mar 17, 2010 #15


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    I need to think about this some more, but I am pretty sure that you cannot use the molecular quasi-continuum as an example of this. The quasicontinuum arises in the molecular case when the spacing between energy levels approaches the homogeneous linewidth of a single spectral line. Thus it is not at all clear on the face of it that the ability to spectroscopically burn a hole in the quasicontinuum shows anything fundamental about time-symmetry. The analysis that you have presented implicitly assumes that the phenomena associated with the broad absorption band due to the quasicontinuum and the narrow hole arise from the same physical phenomena, i.e. a transition between two well-defined states. I do not believe this is the case for the molecular system.

    However, the examples based on atomic physics (Rabi oscillations) clearly cannot be explained in such terms. Can you post a bit more information on those examples?
  17. Mar 19, 2010 #16
    This hypothesis was proposed in the first article in this field [N.R. Isenor, V. Merchant, R.S. Hallsworth and M.S. Richardson, Can.J.Phys. 51, 1281 (1973)] for possible explanation of physical mechanism of infrared multiple photon excitation (IR MPE) of polyatomic molecules phenomenon. Any alternative explanation was absent at that time and despite of well-reasoned criticism [V.T. Platonenko, JETPh Lett. 25, 52 (1977)] this hypothesis became recognized and widespread. However, it is quite clear now that this is one of a number of myths in physics.

    Sufficient density of states (even in principle) can exists only for relatively highly excited molecules (3 – 5 absorbed photons for SF_6 molecules). But the belated experiments in a continuous molecular beam of cold molecules with low intensity continuous wave infrared laser radiation [C. Liedenbaum, S. Stolte and J. Reuss, Chem.Phys. 122, 443 (1988)] clearly show that the laser radiation interacts with the true continuum absorption of unknown nature. This continuum belongs also to cold molecules at ground vibrational and rotational levels of excitation.

    So, the IR MPE of polyatomic molecules is quite trivial phenomenon and non trivial here is only the physical nature of this continuum. Its experimental study is quite simple: we need in a continuous molecular beam, continuous wave infrared laser and cryogenic bolometer. In 1995 – 2000 years I try to convince the experimentalists (Prof. J. Reuss, J. Scoles, R.E. Miller), who had corresponding equipment, to carry out the experimental study of the continuum. However, without any success.

    [/QUOTE] "However, the examples based on atomic physics (Rabi oscillations) clearly cannot be explained in such terms". [/QUOTE]
    Unfortunately, I can not understand the sense of this sentence.

    DrFaustus wrote: [/QUOTE] "experimentalists are actually rather happy to prove that "the abstract nonsense" theorists talk about is wrong". [/QUOTE]
    Where does he meet such experimentalists? Unfortunately, I see around only conformists, who do not want anything to do against a common opinion.
  18. Apr 2, 2010 #17
    Unfortunately, it is clear already that any constructive discussion about time noninvariance in quantum physics will be absent here also.

    Quantum physics now reminds me one theory, which you do not know. This is so-called “scientific communism”. All students in Soviet Union must study it and pass an examination. This “science” has its own professors and doctors. By the way, it is surprising but they survive the change of social and economic structure more easily than other scientists. They began to call themselves as historians and political scientists and continue to teach students for capitalism :smile:.

    “Scientific communism” was a collection of dogmas. The persons, who openly questioned these dogmas, were sent to prisons or mental hospitals. That are the signs of religion: the existence of a dogmas and orthodoxies or power, which safeguard these dogmas.

    So, modern quantum physics becomes resemble to religion: it has the dogma (“the laws of physics are invariant under time reversal”), which does not have any reliable experimental proofs, and hot orthodoxies (like as DrFaustus), who are ready to defend this dogma in any way. And else, you permanently discuss (as the Old Testament) the Stern-Gerlach experiment :smile:.

    There were the dissidents in Soviet Union (like as Sakharov). They fought against the power and dogmas, but the situation was changed only when Gorbachov came and allow the power to drop. Without him the situation would be till now, probably, similar to those in Cuba with Castro.

    I play here a role of a dissident, but we need, obviously, in your own “Gorbachov”. That should be authoritative theorists, who will say: “Hi, colleagues. Let us stop to write nonsense about the laws of physics. They are actually time noninvariant and we must study it”.

    Incidentally, the experimental study of time noninvariance in optics is not very difficult task. We need to study the differential cross-sections of forward and reversed transitions, and to keep in mind that they may not coincide.
  19. Apr 2, 2010 #18
    kvladimir -> You are clearly fighting for something else, not scientific questions. The reason why I claim that experimentalists are more than happy to prove theorists wrong is because as soon as they do it, and it is confirmed by others, they will get a Nobel prize. Prove experimentally that Lorentz invariance does not hold, and I can assure your trip to Stockholm is booked.

    But you seem to not fully understand how science proceeds. Let me explain. In this case, time invariance of the laws at the *fundamental* level is an *assumption* that is encoded in the mathematical formulation of a theory. Starting from this, if you find a *phenomenon* that does not respect it you try to find an explanation. Now, if you find *some* explanation that is compatible with the original assumption, than you're done. Time non invariance might arise for a number of (physical) reasons, yet *not* contradict the original assumption of a *time invariant law*. It is only when *no reasonable explanation* can be found that the original assumption is dropped. And people on here have asked you to provide more details about your experimental results, yet you did not. How come? Are you afraid that someone might explain how and why your results *are compatible* with time invariance?

    Finally, everyone knows that there is an arrow of time. The second law of thermodynamics clearly breaks time invariance for macroscopic systems. Yet, the underlying *microscopic* laws are still *assumed* to be time invariant. And as of today, there are no reasons to think otherwise. But feel free to prove me wrong by posting *details* and results of your experiments.
  20. Apr 2, 2010 #19


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    Just to add to Dr Faustus's comments:

    I knew Roger Miller personally, and I can assure you that he was extremely concerned with correcting misconceptions about physics. One can find many examples in the literature where his papers correct earlier misconceptions about physics based both on theory and experimentation, some of which were quite widely held. In fact, his initial success as a graduate student in the Scoles group was demonstrating that high-resolution, rotationally resolved vibrational spectra could be obtained for van der Waals molecules ... something that was previously held to be a physical impossibility by the great scientists in molecular physics at the time, such as Bill Klemperer, due to the pre-dissociative nature of the vibrationally excited states.

    Furthermore, Roger Miller had a deeper understanding of the underlying physics of spectroscopy than just about anyone I have ever met. So, if you truly proposed your model to him, and he chose not to pursue it, I can only conclude that you failed to convince him of the validity of your analysis. He likely also saw an underlying flaw in your interpretation. Whatever his reasons, I can assure you they had nothing to do with some over-arching desire to not "go against the grain" of conventional physical though, or participation in some broad conspiracy, as you seem to be claiming.

    Your description of the vibrational quasi-continuum as "one of a number of myths in physics" is bizarre in the extreme. It is a well-studied, well-documented, confirmed phenomenon, on which many successful experimental techniques (i.e. IR multi-photon dissociation spectroscopy) are based. Nobel-prize physicist Y.T. Lee used this technique back in the late-70's and early 80's to record high-resolution vibrational spectra of the proton-bound water dimer. There he used a CO2 laser (frequency around 10 microns) to selectively dissociate only those ion clusters that had absorbed a single photon in the O-H stretching band at <3 microns, and hence were closer to the vibrational quasicontinuum.

    Anyway ... my impression from your posts is that you have already made up your mind about this, and are probably too cynical and jaded to engage in a rational discussion, but on the other hand, everyone deserves a fair chance to be heard. Anyway, here are some questions for you so I better understand your argument:

    For the SF6 system, your claim is that the lifetimes for stimulated absorption and emission of IR radiation are different by many orders of magnitude, correct?

    From the only paper of yours that I could find in arXiv on the subject, (which does not contain any original data and has not been peer-reviewed as far as I can tell), you are basing this on the observation that in a two-laser pump-probe experiment, it is possible to burn a hole in absorption line-shape of the fundamental vibrational band, correct?

    If I understand the above correctly, it seems you are claiming that the observed linewidths of the absorption band is due exclusively to homogeneous broadening. So can you please explain in detail why you think it is possible to burn a hole in a homogeneously broadened band? Hole-burning implies *selective* population depletion of a particular subset of states contributing to a spectroscopic band, and thus it is clearly possible for heterogeneously broadened bands. Therefore the conclusion I would draw from your observations is not that both bands are homogeneously broadened, but rather that there is an underlying heterogeneous broadening mechanism that gives rise to the observed phenomenon.
  21. Apr 7, 2010 #20
    In the beginning of this thread I give the references for the number of e-prints. There are more than two tens of my e-prints there. In most of it I discuss the concrete experimental results (there are not my own experimental results). It is impossible to put all this information in the forum thread.

    If you have different opinion about the physical explanations of those experimental results, we can discuss your and my opinions. But till now I do not see any signs that you read even one of those e-prints (in contrast to SpectraCat).
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