Talk:List of unsolved problems in physics/Archive 2

Recent Major Revisions Deleted Most Important Questions
As far as I can tell, Dark Matter and Dark Energy/Cosmological Constant problem have been deleted. These are right up there with the most important ones. Do people agree? 9:32, 26 March 2009 (ET). —Preceding unsigned comment added by 128.100.75.232 (talk) 13:33, 26 March 2009 (UTC)


 * These sections have been were moved to Unsolved problems in astronomy. Now they have been restored, so they are in both articles. Gandalf61 (talk) 14:36, 26 March 2009 (UTC)

Spin is not an unsolved problem
The article lists this question as an unsolved problem in physics: What is subatomic particle spin? This is silly. Spin is understood perfectly well. The fundamental particle in nature are quantum fields with 2 or 3 components (spin 1/2 or spin 1) at every spacetime point, where those components transform under the Poincare group. It's not intuitive, but it has a complete mathematical description in precise agreement with experiment which isn't seriously debated. If you ask a theoretical physicist "Is the understanding of spin an outstanding question in physics?" he will say no.

There is a reference to a "Ask a scientist" post. There, Tim Mooney (whoever that is) says Although we do not have a deep understanding of what spin is, we do have a mathematical description of how it behaves... As far as I can tell, this is just him expressing the fact that spin is unintuitive. He then says Why spin should be the thing that distinguishes stuff from the forces between stuff is unfathomable to me, and that spin should do this in such an apparently arbitrary way (half-integer as opposed to integer) suggests to me that our understanding is fundamentally flawed... It is certainly surprising that spin has this relation to statistics, but it's not an unexplained empirical fact. It can be demonstrated theoretically that (1) indistinguishable particles obey either fermion or boson statistics and (2) integer-spin particles can't consistently be fermions and half-integer-spin particle can't consistently be bosons (see, e.g. "PCT, Spin statistics, and All That"). The only possibilities are integer-spin bosons and half-integer-spin fermions. That might be an unsatisfying explanation for some (it certainly is for me), but that's completely different than an "unsolved problem in physics", in the same vein as questions about dark matter.

I'm removing the section, and moving the question about the 3 generations of matter to the high-energy section. If you want to include things like "What is subatomic particle spin?", it needs a new section (or really, a completely new page) with a title like "Explanations that some physicists find unsatisfying". Njerseyguy (talk) 06:15, 31 July 2009 (UTC)

Island of stability
Unlike every other question in the "Theoretical questions" section, the existence of the island of stability is not a question of fundamental physics. That is, the island of stability is an intractable calculational problem, but no one doubts that the fundamental description of what is going on is strong force/standard model dynamics. It should probably be put in a different section. Njerseyguy (talk) 06:26, 31 July 2009 (UTC)


 * You could make the same argument about high-temperature superconductivity just being an intractible analysis of electron behaviour. In both cases, I think that the topics do belong on the list, with the caveat that they're questions of devising an appropriate model for emergent behavior (nuclear shell structure and stability in the case of the island of stability, and a specific case of condensed matter physics in the case of superconductivity). --Christopher Thomas (talk) 06:13, 8 November 2009 (UTC)


 * The task of a theory in physics generally is to explain observed behavior in terms of a model. Without proof, you don't know what the model predicts, opening the possibility that the model fails. Put differently, as long as the computational complexity is too high to model some observed phenomenon, the theory is not (yet) falsifiable. Paradoctor (talk) 07:23, 8 November 2009 (UTC)

Merger proposal
This article was proposed to be merged with Unsolved problems in astronomy in June 2009. Is there a need for these to be merged? Both are substantial in their own right, although the astronomy article does have a majority of problems that could well be listed in the physics article. Lantrix :: Talk :: Contrib :: 14:40, 8 August 2009 (UTC)

Age crisis
The text of the section describing the Age Crisis seems to imply that measurements of present stellar luminosity were the problem, whereas I could have sworn it was estimates of past luminosity via oversimplified models of stellar evolution that were the problem. I've asked about this at Talk:Age Crisis, so it's probably best to keep answers/comments there (to avoid splitting the discussion). --Christopher Thomas (talk) 06:09, 8 November 2009 (UTC)

Black holes
The sentence "Do they really exist?" is not very good as the existence of black holes in the universe is well supported by astronomical observation. helohe 09:34, 27 July 2005 (UTC)


 * No, we've found super-dense objects, and we've referred to them as "black holes" for convenience, but we don't yet know whether they have the "novel" GR-predicted properties (zero radiation, central singularity, causally-disconnected interior) that distinguish a black hole from, say, a old-fashioned Eighteenth-Century dark star. If someone finds an island and decides to name it "Atlantis", it doesn't mean that they've "found Atlantis" or "proved that the lost continent of Atlantis exists". ErkDemon 20:09, 29 July 2005 (UTC)
 * The current Big Bang Model is a QFT in a curved spacetime. Unfortunately, no such theory is mathematically well-defined; in spite of this, theoreticians claim to extract information from this hypothetical theory. On the other hand, the super-classical limit of the not mathematically well-defined QED in a curved spacetime is the mathematically well-defined Einstein-Maxwell-Dirac system. (One could get a similar system for the standard model.) As a super theory, EMD violates the positivity condition in the Penrose-Hawking Singularity Theorem. Thus, it is possible that there would be complete solutions without any singularities-Yau has in fact constructed some. Furthermore, it is known that the Einstein-Maxwell-Dirac system admits of solitonic solutions, i.e., classical electrons and photons. This is the kind of theory Einstein was hoping for. EMD is also a totally geometricized theory as a non-commutative geometry; here, the charge e and the mass m of the electron are geometric invariants of the non-commutative geometry analogous to pi! I love the irony in the fact that it takes EPR type results to falsify Einstein's UFT program!unsigned comment added by David edwards (talk • contribs) 20:40, 26 January 2010 (UTC)

Saturn
Are the spokes of the rings an unsolved problem in physics ? -- Amtiss, SNAFU ? 20:03, 19 January 2006 (UTC)

No.

However the rotation rate of Saturn (i.e. the length of a Saturn day) is most certainly an unsolved problem and, perhaps more importantly, so is the reason for the magnetospheric oscillations that make this rotation rate so difficult to measure. DanielWent (talk) 18:49, 5 July 2010 (UTC)


 * Thanks for adding this one. I wasn't aware of it, and I love it. Paradoctor (talk) 15:27, 5 July 2010 (UTC)

Corona of the sun
Um, while I admit I'm not a science brain, I was always taught that the corona of the sun was hotter than the sun's surface because the corona is where all the energy from the fusion reactions was being given off. So, unless I'm very wrong, this doesn't seem like an unsolved problem in physics.

The corona should, if anything, be less dense then the material directly beneath it. The gas laws would dictate that it should then be at a lower temperture as it must be at a lower pressure. Heat equation implies that the radiation should also be lowest on the surface, not highest. You were taught wrong.

(- Simulcra 21:14, 1 June 2006 (UTC))


 * A quick look at the corona article shows that the question is still not resolved.Pcarbonn 21:50, 1 June 2006 (UTC)

I think that's because the corona is a large layer of photons, and I also think that if there are more photons, there is more heat. - AngelOfMalevolence —Preceding unsigned comment added by 203.167.31.130 (talk) 10:47, 14 June 2008 (UTC)

The corona is NOT a layer of photons. It is a layer of protons and electrons (called a plasma) with a density much lower than the surface of the Sun. In fact the density is so low that collisions between different particles are rare so it's a mistake to think about this like the gas that makes up the atmosphere on Earth. Basic physics though - if the corona is hotter than the surface of the Sun, there must be some extra source of energy heating particles up and making them move faster. Heating by solar radiation would predict a corona which is cooler than the surface of the sun, not hotter, so that explanation goes out the window. Scientists are fairly sure the missing energy source is magnetic reconnection but, as the article says, it's still somewhat uncertain why reconnection works quite as well as it does. —Preceding unsigned comment added by 89.241.154.56 (talk) 12:46, 5 July 2010 (UTC)

Time travel
Time travel lists 'Is time travel theoretically and practically possible? If so, how can paradoxes such as the grandfather paradox be avoided?' as an unsolved problem and links here but there's no mention of this here and only brief mention of time travel in "The cosmic censorship hypothesis and the chronology protection conjecture" Nil Einne (talk) 22:48, 8 February 2010 (UTC)


 * There are those who think that time travel is logically impossible, so you better provide a couple of good citations when you add it. Aside from that, well spotted. Paradoctor (talk) 08:01, 9 February 2010 (UTC)


 * The entire article recently underwent a large revision. It could still stand cleanup, with splitting of some entries and pruning of others. I support the present version's phrasing of the time travel question in terms of closed timelike curves, but I agree that this should probably be its own entry. Regarding the grandfather paradox, I'd instead state that part in terms of the Novikov self-consistency principle (i.e., "are events in spacetime geometries containing closed timelike curves forced to be self-consistent?"). --Christopher Thomas (talk) 08:33, 9 February 2010 (UTC)


 * This seems to be a case of mispaste. ;) Paradoctor (talk) 08:45, 9 February 2010 (UTC)


 * How so? From what I can tell, for both this unsolved problem and several others, it looks like overly-aggressive streamlining by someone who wasn't very familiar with the topic. Useful as a starting point, but could use revision. The entire article was refactored a couple of months ago (this was the same editing pass that removed the footnotes indicating whether a problem was assumed to have been solved, disputed as being a problem, and so forth). --Christopher Thomas (talk) 17:40, 9 February 2010 (UTC)


 * Do you realize that this is the talkpage for List of unsolved problems in physics? The discussion in this section is about whether to include time travel in this list. I don't quite see how the organization the time travel article is relevant. Paradoctor (talk) 20:07, 12 February 2010 (UTC)


 * I am talking about this article . It underwent a major reorganization recently. Click the "history" link in the template I just provided you if you want to investigate for yourself. The list was streamlined by someone who looked like they had good intentions but was overly-aggressive, grouping several entries together that shouldn't have been grouped. Time travel/CTCs was one such topic. --Christopher Thomas (talk) 20:26, 12 February 2010 (UTC)


 * Ah, okay, my bad. I missed the parenthetical remark linking CTCs to time travel.
 * Mashing up censorship and CTCs is nonsense. Also, the name of the problem is time travel. CTCs are a characteristic of solutions that appear to allow time travel. The question of whether a quantum gravity would rule them out is a subproblem. Chronology protection/Novikov self-consistency are attempts at solving the time travel problem by formulating principles that exclude time travel. As I said, a couple of good sources, and we have a time travel entry. Paradoctor (talk) 21:09, 12 February 2010 (UTC)

Additions moved to the talk page
I've moved a couple of uncited recent additions here, for further discussion before integration:


 * Bow shock: Why are planetary and other shocks orientated with the dense Bow Shock on the ecliptic polar, the direction of orbit round the sun, with an asymmetric relationship to Solar Winds, rather than just orientated to the solar vector?  And what propagates the standing wave of active oscillating particle activity?


 * Gravitational Lensing:  What causes the extreme delays in parts of lensed light of up to 3 years, when delays predicted by gravitational mass estimation should be more than an order of magnitude less?

Regarding bow shock, this effect isn't mentioned in the main article. Citations describing it and showing that it's considered an unsolved problem would be handy. Regarding gravitational lensing, these delays would be a very important observation - have they been confirmed, or has only one group published about them? Citations from several groups independently measuring it would handy. --Christopher Thomas (talk) 19:09, 30 March 2010 (UTC)


 * Yes, I'd like to see sources, too. Paradoctor (talk) 19:59, 30 March 2010 (UTC)

Photoelectron?
I had only heard that noun when used to refer to an electron extracted from an atom through the photoelectric effect, and indeed "Photoelectron" redirects there. But that doesn't appear to make much sense in this context. Am I missing something? ― _ _ _ A._di_M. (formerly Army1987) 18:42, 6 April 2010 (UTC)


 * This looks like something took from their  article. The reference they cited for it is here. Near as I can tell, the reference itself contains nothing mysterious - it's talking about electrons emitted from beam pipe walls due to synchrotron radiation, I think (it assumes the reader already knows where they come from), and how to best configure magnetic fields in an accelerator so as to keep the resulting electron cloud away from the beam itself (the beam scatters against it, causing defocusing). This is an ongoing problem with that article (references don't seem to match content, and content itself is very vague). --Christopher Thomas (talk) 19:15, 6 April 2010 (UTC)


 * "reference itself contains nothing mysterious": My reading too, removed the entry as unsourced. I like my fringe theories, but I also like my sources. Paradoctor (talk) 20:11, 6 April 2010 (UTC)

Empirical phenomena lacking clear scientific explanation - Particle Physics topics listed under "Cosmology and astronomy"
I can understand why Baryon asymmetry and neutrino masses (and possibly electroweak symmetry breaking) are listed under Cosmology and astronomy, but I don't understand why the proton spin crisis, non-perturbative QCD, and the strong CP problem are listed under Cosmology and astronomy. These are unsolved problems in particle physics, not Cosmology. This classification is wrong and must be fixed. If I had my two cents electroweak symmetry breaking would also be listed as a problem in particle physics.

I looked at some of the talk page entries above and noticed some bickering between astrophysics and particle physics. This is childish and embarrassing. Both fields are tremendously important, to science as a whole and to each other. I am a PhD candidate in theoretical physics studying non-perturbative QCD, so I am certainly not an expert, but I know enough to know what is a problem in Cosmology and what isn't. —Preceding unsigned comment added by 67.225.127.134 (talk) 18:35, 10 April 2010 (UTC)
 * Yeah, that's weird. I'm going to fix that. ― _ _ _ A._di_M. (formerly Army1987) 19:36, 10 April 2010 (UTC)


 * Looks great. Thanks! —Preceding unsigned comment added by 67.225.127.134 (talk) 03:39, 11 April 2010 (UTC)

What is the point of this page?
Um, I'm not really sure what the point of this page is. It sort of gives a false impression that physics is almost done. When actually, as soon as you get into any vaguely applied area there are oodles of rather embarrassing 'unsolved problems'. The implication that there are only about five problems in biophysics is particularly laughable. Maybe it should be reduced to just a list of problems in fundamental physics? UnexpectedTiger (talk) 20:48, 27 May 2010 (UTC)
 * Agreed. Some of the editors have been a little over-enthusiastic in their estimations. One example, calling Quasars a "problem recently solved" may be going overboard when our understanding of the universe is changing almost daily. I'm enthusiastic about how much we've learned, but I also remember what Albert Michelson said in 1903: "The more important fundamental laws and facts of physical science have all been discovered, and these are so firmly established that the possibility of their ever being supplanted in consequence of new discoveries is exceedingly remote." We can't even explain "simple" lightning yet. It's all around us, all the time ... but not included on this page. Can't solve by ignoring. Yet we're pretty sure we've "solved the problem" of galaxy-sized objects 10 billion light-years away?? Twang (talk) 06:09, 9 July 2010 (UTC)
 * If you doubt that the nature of quasars is a recently solved problem, you might want to cn the offending entry. Paradoctor (talk) 19:43, 9 July 2010 (UTC)


 * Very sure, thanks. In the 1980s, we didn't know if these radio sources were nearby or far away, or the mechanism for their energy production. We now know that they're active galactic nuclei far away, and that their energy is derived from accretion of matter into black holes and the associated relativistic jets produced during this process. "Solved" in this context means reaching a general agreement as to what a phenomenon is and what the mechanisms involved are. Cases where more detail is required (i.e., where the "unsolved problem" is with the details of a specific model or phenomenon) are spelled out explicitly in the article text. --Christopher Thomas (talk) 21:59, 9 July 2010 (UTC)
 * "general agreement": In that case, reliable sources should exist stating this. How about providing one or two? Paradoctor (talk) 04:41, 10 July 2010 (UTC)


 * These are already provided at Quasar. If you feel references at that article are insufficient, please post on that article's talk page, and maybe also at WT:ASTRO. --Christopher Thomas (talk) 21:12, 10 July 2010 (UTC)


 * Wikipedia talk:Stand-alone lists/Archive 2. The bit about articles always being referenced on their own is buried somewhere in the policy jungle. I would add the refs myself, but you seem better qualified to pick the appropriate ones. Paradoctor (talk) 06:45, 11 July 2010 (UTC)


 * I've copied two of the most relevant references to the "quasar" entry in this article. --Christopher Thomas (talk) 22:27, 12 July 2010 (UTC)


 * Much appreciated. Paradoctor (talk) 16:14, 13 July 2010 (UTC)

Cyclic universe
The rewording of "Cyclic universe Is the universe cyclic in nature or a one-off occurrence? Have space and time existed forever?" to "Ultimate fate of the universe Is the universe heading towards a Big Freeze, a Big Rip, a Big Crunch or a Big Bounce ?" does not reflect the same ideas. The cyclic version covers more possibilities and does not limit itself to particular scenarios or the notion of an ultimate fate. Androstachys (talk) 06:38, 28 August 2010 (UTC)


 * Big Bounce is the cyclic model (a side question is why do we have two separate articles on the same topic ?). The basic unsolved question is just what the long-term future of the universe is, not whether it conforms to one very specific model. As you seem to dislike the word "fate", I have removed that, and combined the two entries to include a link to cyclic model as well as the other articles. Please discuss rather than continuing to edit war. Gandalf61 (talk) 07:02, 28 August 2010 (UTC)
 * I do prefer discussion to edit warring, but your first edit of my contribution simply read "re-word - more neutral and more general" which is rather dismissive and has more than a hint of POV, besides involving no discussion. Androstachys (talk) 15:56, 28 August 2010 (UTC)


 * I endorse User:Gandalf61's version. While the terms aren't precisely identical, the "Big Bounce" scenario is the most widely-considered cyclic universe model at present, and Cyclic universe is already linked from the lede of Big Bounce, so users wishing to learn about other models already can. Giving it its own entry gives it undue weight. --Christopher Thomas (talk) 08:13, 28 August 2010 (UTC)
 * Perhaps part of the purpose of a "List of unsolved problems in physics" should be to make users aware of dissenting and even fringe opinions and not to only recognise the "flavour of the month" model. Not "'precisely' identical?" - are there degrees of identical? Androstachys (talk) 15:49, 28 August 2010 (UTC)
 * Please read WP:UNDUE. If items that are widely considered to be unsolved problems only get a sentence or two, fringe theories do not belong here at all. They are given appropriate coverage in other articles already. --Christopher Thomas (talk) 20:58, 28 August 2010 (UTC)
 * The title of the article is List of unsolved problems in physics. A cyclic universe is NOT regarded as a fringe theory and certainly belongs here - the type of universe we live in being a MAJOR unsoved problem. Androstachys (talk) 07:22, 29 August 2010 (UTC)
 * You're the one who brought up fringe theories, not me. The same policy (WP:UNDUE) applies to dissenting or other minority opinions - give them space in proportion to how noteworthy they are. Regarding cyclic model, the objections have already been explained to you, but to recap, Big Bounce covers what is presently the most noteworthy version of the idea, and links to the cyclic model page, so mentioning it alone is sufficient. --Christopher Thomas (talk) 09:03, 29 August 2010 (UTC)


 * What about merging the two into this:
 * Ultimate fate of the universe: Is the universe heading towards a Big Freeze, a Big Rip, a Big Crunch or a Big Bounce? Will its history start over and over again?
 * A. di M. (talk) 15:10, 29 August 2010 (UTC)


 * Actually, now that I've seen Gandalf's last version, I think it's OK. A. di M. (talk) 15:46, 29 August 2010 (UTC)

Confinement
Shoudn't there be an paragraph about the confinement Problem? At least it is not explicitely mentioned in the QCD paragraph. Eventhough there is stong evidence from lattice QCD that there is quark and color confinement in QCD (-> linear rising potential), the mechanisms behind are still unclear. -- opinions? RolteVolte (talk) 14:21, 12 September 2010 (UTC)


 * How is this an unsolved problem? We know why color confinement occurs, know about how asymptotic freedom lets you create situations where its effects are less pronounced, and are in the process of studying unusual states of matter (quark-gluon plasmas, color glass condensates) that explore the behavior of color-confined particles under interesting conditions.


 * As I understand it, the "unsolved problems" page is for phenomena that we don't have a good theoretical model for. --Christopher Thomas (talk) 19:19, 12 September 2010 (UTC)


 * Do we really know why confinement of quarks and gluons occurs or better how it occurs from the QCD Langragian? To my knowledge on the one hand, there is no proof that QCD is a confining theory and on the other it is not clear how the linear potential, that can be extracted from lattice QCD simulations, is created by the fundamental interactions of quarks and gluons.
 * I also think that "unsolved problems" is for phenomena without theoretical description, but I don't see them in this case. RolteVolte (talk) 07:25, 13 September 2010 (UTC)


 * Yes, we do. That is why QCD has the mathematical form it does - the model was successful because it explained how hadrons could be composite particles without the component particles (quarks) being observable in isolation. All of this happened many years before it was practical to perform lattice QCD simulations. --Christopher Thomas (talk) 16:44, 13 September 2010 (UTC)


 * I do not think so. On the one hand WP itself states, that there is no proof for QCD to be confining (see Color confinement 1st sentence in chapter Origin), but beliving WP or not, there is a quite recent article about that topic http://arxiv.org/abs/hep-ph/0610365 which seems to me quite reliable. I agree with you on the aspect of assymtotic freedom, that QCD as non-abelian gauge theory is assymtotically free in the UV-region, but that's not the point here. The point is: is it shown that QCD is confining in the Infrared? Or spelled otherwise: why did nobody ever measure an single quark or gluon but only compound objects, hadrons? And I still think this question is not answered, yet, and that's why I think that Confinement should be on the list of unsolved problems RolteVolte (talk) 18:16, 13 September 2010 (UTC)

Although there are various heuristic ways of arguing that QCD exhibits color confinement, it has never been shown rigorously. Showing it rigorously would involve solving the Yang-Mills mass gap Millenium Prize problem. So yes this is definitely an open problem.TimothyRias (talk) 21:24, 13 September 2010 (UTC)


 * Agree with TimothyRias. Of course it has to be stated clearly that we know what the phenomena are, we know the exact equation that underlies the phenomena, and the only unsolved problem is showing with mathematical rigor that the phenomena arise from the equation. Some empirically-minded physicists (like Richard Feynman) would (dismissively) call this an unsolved problem in math rather than physics, but I think it's OK here.
 * Actually very little of quantum field theory is understood with mathematical rigor, as I understand it -- for example, the Feynman path integral, etc. Even in QED, is it proven that the perturbative expansions converge to a well-defined result consistent with a nonperturbative analysis? I'm not sure...
 * Maybe there should just be one more-general entry: "Mathematics underlying quantum field theory", encompassing this whole area, with QCD as an important special case? Just an idea... --Steve (talk) 23:02, 13 September 2010 (UTC)

I added now an item about the confinement problem straight below the point about "QCD in the non-perturbative regime", since it is an problem, where there is a strong experimental evidence,-> no free quarks, gluons, but no rigorus theoretical treatement.RolteVolte (talk) 08:34, 14 September 2010 (UTC)

Theory of everything
Is there a theory which explains the values of all fundamental physical constants?[3] Is there a theory which explains why the gauge groups of the standard model are as they are, why observed space-time has 3 + 1 dimensions, and why all laws of physics are as they are? Do "fundamental physical constants" vary over time? Are any of the particles in the standard model of particle physics actually composite particles too tightly bound to observe as such at current experimental energies? Are there fundamental particles that have not yet been observed and if so which ones are they and what are their properties? Are there unobserved fundamental forces implied by a theory that explains other unsolved problems in physics?

Is there a answer to this problem in three basic excepted laws of physics

1 all forces are equal and opposite

2 energy/force cannot be created or lost it can only be changed

3 velocity will always increase the weight of mass when compaired to the same mass at rest.

Within these three laws there is a basic insight that contradicts with the current perception of big bang and black hole, this is that at these two events everything starts or finishes when in fact each of these above laws above indicate it is not possable to have such a event.

The current perception originates from the fact our elemental mathematical system fails at the sigularity, this leads to the current view because we cannot prove it we cannot understand it, this however also indicates we cannot prove it is the start and finish of everthing.

In very simple terms mr einsteins relativity limits space to a fourth dimension of time in fact his equasion E=Mc2 energy is = to the mass of light squared can only ever represent the energy/force contained in the mass of light at a singular time.

The only way relativity and quantom will ever be reconciled is when mathematics can predict the actions and reactions of changes to the mass of light over time will we answer this problem.--81.153.70.101 (talk) 11:34, 7 November 2010 (UTC)

Multiverses
Aren't multiverses part of metaphysics rather than physics, if they are fundamentally not observable? Isn't the multiverse discussion to be separated from the discussion whether other systems of natural laws theoretically may exist (if only because a parallel universe may have the same systems of natural laws as we have)? This theory is to be judged solely from its internal consistency, as it is not veryfyable. Which is normal for mathematicians, not for physicists... 09:03, 10 November 2010 (UTC) Rbakels (talk)

History
It might be interesting to mention that at times physicists believed that physics was (almost) "finished" (perhaps in a separate lemma - sorry if it is already there and I missed it). Wasn't this the case around 1900? When I studied physics around 1970, I recall that there was a similar perception that physics should concentrate on new applications of known phenomena, because nearly all phenomena were known, except perhaps some uttery esoteric elementatry particle problems supposed to be of no practical relevance whatsoever (and forever!). In hindsight, it is just funny that history repeats itself in this respect too. I don't follow the developments in physics anymore - but during a recent visit to CERN in Geneva I was amazed about the amount of big unsolved problems - like the fact that there sppears to be much more "black matter" than real matter of the common variety in the universe. Rbakels (talk) 09:13, 10 November 2010 (UTC)

Diffuse interstellar bands
What do people think about adding diffuse interstellar bands to this list? (under experiments, astronomy) They've been known about for almost a century, but the carriers have never been identified. The article on the topic isn't great, but it's undoubtedly a massive problem. Several people have independently suggested to me that if/when the carriers are identified it could win a Nobel Prize. Modest Genius talk 21:41, 20 November 2010 (UTC)

Secular variations of the planetary orbits
This "issue" has been repeatedly inserted by multiple editors and repeatedly removed by multiple editors (including myself), so I think a clear list of the issues is needed. First off, the claim that JPL revises their ephemerides every 20 years due to a small secular trend is simply false; JPL (through the HORIZONS system) is actually updating these all the time based on improving knowledge, and moreover, according to them the updates are most commonly due to improving knowledge about the orbits (or existence) or small bodies, like planetary satellites and asteroids. Secondly, the papers being put forward as cites for this claim do not, in fact, make this claim at all; the most relevant provided so far (YB Kolesnik, et al) proposes the existence of such a secular trend based on observations of deviations between BDT and TAI, and makes no mention of JPL updating its ephemerides. Lastly, doing a google scholar search on this paper turned up no citations to it at all; checking another Kolesnik paper turned up 6 cites, four of which were by Maserliez (the progenitor of this currently fringe cosmological theory) and one by Arbab (fringe cosmologist from Khartoum; see a discussion of his work at Talk:Secular variations of the planetary orbits). There doesn't appear to be any evidence that this is either a valid concern -- i.e., that an unexplained secular trend in planetary orbits has been rigorously observed at all-- or that it represents a well known "unsolved problem" as a result. What it does look like is a small community of fringe cosmologists working together to develop a new theory; whether or not it turns out to be correct (IMO not likely) is not a matter for wikipedia to decide. siafu (talk) 18:27, 30 March 2011 (UTC)


 * You might also be interested in in that case. I removed a small bit but left most of it, not being sure William M. Connolley (talk) 18:43, 30 March 2011 (UTC)

Pioneer anomaly solved
http://www.technologyreview.com/blog/arxiv/26589/?ref=rss

75.4.205.0 (talk) 07:15, 31 March 2011 (UTC)

Quantum Measurement
How about including quantum measurement problems - what happens during a quantum measurement to cause the wave function to collapse, and what defines when a measurement takes place? 98.225.38.209 (talk) 06:45, 26 May 2011 (UTC)ATBS
 * It's already listed, under theoretical/other. -Jordgette (talk) 08:56, 26 May 2011 (UTC)

Elucidates
Do anyone mind if I remove all the elucidate templates on this page? There's a whole article wikilinked behind every topic and it seems to me that's elucidation enough. Thanks for your inputs Woz2 (talk) 21:24, 27 May 2011 (UTC)


 * I am trying to translate this article from English to Chinese. While doing this task, I find that certain contents are inadequately explained.  For example, in the paragraph for accretion disc jets, a question is asked about the overtones.  However, I couldn't find any description in the article for the quasi-periodic oscillation about overtone.  Most of the problems in this article are very deep, and demand better explanations.  Otherwise, the readers are forced to go to the web to search for more details.-LaoChen (talk)04:49, 28 May 2011 (UTC)

Solved Physics Mysteries
This "List of unsolved problems..." is a very fine article. Parts of its outline and text were used in "Solved physics mysteries" http://binarymechanics.blogspot.com/2011/06/solved-physics-mysteries.html to tabulate progress in the development of binary mechanics to date. Thanks to the author(s) of the "List...". HotBasic (talk) 20:17, 13 June 2011 (UTC)

Use of unsolved physics problem to solve other physics problems?
I have a logical problem with the claim that the "Age Crisis" has been solved by the addition of dark energy, which is itself listed as an unsolved problem in Physics. This makes no sense. — Preceding unsigned comment added by 114.198.80.51 (talk) 13:37, 4 July 2011 (UTC)
 * I agree — that's not very consistent. I think we should remove the mention of dark energy from the Age Crisis listing and limit the issue to the former estimated age of globular clusters. -Jordgette (talk) 17:30, 4 July 2011 (UTC)

Field-Hypothesis for Consciousness
In a very old article, titled " A Hypothesis for Consciousness" published in the bulletin of Bio-Medical Society of Gujarat, published in 1980s, a field-hypothesis for 'consciousness' has been proposed by Hasmukh K. Tank. The article also contains a proposed experiment for its verification.
 * Neat! I might post that on the talk page for Consciousness, as it would probably be more relevant there. --Goodbye Galaxy (talk) 19:49, 8 August 2011 (UTC)

Sentience
Would an entry regarding sentience be a good idea (under the "biological physics" section)? As far as I know, it is a totally unexplained phenomenon, and it certainly is perplexing that specific arrangements of particles can become self-aware. --Goodbye Galaxy (talk) 20:13, 6 July 2011 (UTC)
 * No one seemed to object, so I added the entry. Let me know if you feel it needs tweaking. --Goodbye Galaxy (talk) 18:22, 25 July 2011 (UTC)
 * Good idea to include the topic but your wording suggests individual particles can be sentient rather than some part of the organism as a whole which is the aggregate of the particles. In other words, IMHO, it is probably uncontentious to suggest that self-awareness lies in the human brain but not that one carbon atom within it can be self-aware.
 * George Dishman (talk) 18:14, 15 August 2011 (UTC)
 * Hmm, you're right. I tweaked the wording in the article to refer to "arrangements of otherwise non-sentient particles". C'est bon? --Goodbye Galaxy (talk) 18:43, 15 August 2011 (UTC)


 * I don't think this belongs here. For one, sentience is related to information theory rather than physics; it is a high-level concept, and I have not heard of a reason to assume that it depends on the exact physical realization. Furthermore, physics concerns fundamental or statistical questions, not so much the detailed cases that can be achieved. Topics like building a spaceship would be too specific to belong in a physics section. The topic of sentience is no different. Please move it to a different page, for example one related to intelligence, information, or self-awareness. Vandroiy (talk) 12:33, 11 November 2011 (UTC)
 * I concur. I've never understood why many people consider sentience or consciousness mysterious or unexplained. If you just look at the various levels of sentience in animals as you go up in complexity, from a one-celled Euglena with its eyespot receptor as well as internal homeostasis, you see that human sentience is nothing more than an extremely complex emergent feature of animals' ordinary observational and self-observational faculties.  -Jord gette  [talk]  21:48, 11 November 2011 (UTC)

Condensed Matter
According to this article, it seems condensed matter (hard and soft), biophysics, and network physics do not exist. I guess myself and 80% of physicists are out of the job!

P.S. the reason I don't edit this myself is that I've been reverted on every attempt and bit on every talk post, even just to remove that completely ignorant disclaimer in the "Biological Physics" section. SamuelRiv (talk) 20:42, 25 August 2011 (UTC)


 * If you've been reverted, there's probably a reason. One of the first times I visited this article, I made an addition, and it has been there ever since. If you source your entry properly, your entry fairly summarizes the source, and the source indicates that the issue is indeed an unsolved problem in physics, then you should be fine.  -Jord gette  [talk]  22:17, 25 August 2011 (UTC)

It seems to me Cold Fusion is out of place here. It's not a 'major unsolved problem', rather it's a 'minor discrepancy' kept alive by the potential (though unlikely) huge economical impact. I also think Non-equilibrium thermodynamics should be included; e.g., the explanation of heat loss in Magnetic confinement fusion, devices with the steepest laboratory-scale thermodynamic gradients, is still far away (and potentially hugely important). Milligen (talk) 09:51, 1 September 2011 (UTC)

Expert tag
Someone added an expert tag without discussion here first. I'm no expert, but the article seemed pretty solid to me. What do others think? --Goodbye Galaxy (talk) 13:31, 12 October 2011 (UTC) To be honest, I don't know if adding an expert would work. Even a panel of experts couldn't agree on what's solved and what's unsolved. — Preceding unsigned comment added by 198.110.216.28 (talk) 15:06, 10 November 2011 (UTC)
 * Yes, I don't think the tag is necessary. I'm removing it.  -Jord gette  [talk]  20:07, 10 November 2011 (UTC)

Big Rip
I thought that the 2011 Nobel Prize was awarded to Perlmutter, Riess, and Schmidt for discovering that the expansion of the universe is accelerating, which means we are going to go into a big rip, however there is still a section titled "Future of the Universe" in the "Quantum gravity, cosmology, and general relativity" section. Correct me if this I was wrong and this is supposed to be there. 173.74.167.224 (talk) 01:32, 27 October 2011 (UTC)
 * It's all still very uncertain. Goodbye Galaxy (talk) 14:23, 27 October 2011 (UTC)

The Omar Question
Why was this anomaly removed? I believe its a real fact of unsolved physics that needs more attention. — Preceding unsigned comment added by 116.212.225.158 (talk) 02:08, 9 March 2012 (UTC)

Noumenon problem
Hi. Can we describe the noumenon problem in the article &mdash; in which science can only describe the components or interactions of matter &mdash; where it is not possible to describe things-in-themselves? Thanks. ~ AH1 (discuss!) 14:31, 29 October 2011 (UTC)
 * That's certainly not an unsolved problem in physics as it's not really a scientific problem at all, and really more of a potential, general, philosophical or epistemological issue. siafu (talk) 17:13, 29 October 2011 (UTC)

Dark flow
The "Dark flow" has too few contenders, only 7 articles is written about it, so I propose that it is demoted from the list of unsolved problems, until there are enough debate about it proving its existence as a problem. Rursus dixit. ( m bork3 !) 17:16, 27 December 2011 (UTC)

Inclusion criteria
Do we have some ideas for inclusion criteria for this list - i.e. what should go and what shouldn't? From my (admittedly biased!) perspective, it seems to be dominated by high-energy/mathematical physics problems as compared to condensed matter/experimental problems. To give an example, I'd have imagined this list to mention, say, topological insulators and quantum computation. I'd like to hear other opinions on this.

Cheers,  S Pat   talk 20:27, 25 March 2012 (UTC)


 * I would imagine notability and a reliable secondary source calling it an unsolved physics problem would be good criteria. IRWolfie- (talk) 15:21, 1 April 2012 (UTC)


 * Yes, I was thinking of something similar (it's also what they've done at List of common misconceptions). Obviously, many entries in this list do not fit that criterion - I'll see what I can do with regards to referencing. Thanks,  S Pat   talk 15:25, 1 April 2012 (UTC)

Source life time
Should a specific lifetime of sources be applied to determine if it is sitll unsolved? We can set it up so that citations get automatically marked after say, 10-15 years old with the update after template. IRWolfie- (talk) 15:30, 1 April 2012 (UTC)


 * As of now I'm just going by what the (newest source that I can find) says - however it would be nice to make this more systematic.  S Pat   talk 23:05, 10 April 2012 (UTC)

Restructuring
I'm restructuring the list - removing the theory/expt distinction and rearranging per field. Hopefully that should improve readability. Let me know if there are any suggestions. S Pat  talk 23:05, 10 April 2012 (UTC)

Great work! — Preceding unsigned comment added by 92.22.178.105 (talk) 21:34, 28 June 2012 (UTC)

Origin of Elements in the Cosmos
"What is the origin of the elements in the cosmos?"

Is this unsolved?

I though big bang nucleosynthesis deals with the lightest elements pretty well: http://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis.

As for heavy elements up to around atomic number 56, we have stellar nuclear fusion: http://en.wikipedia.org/wiki/Nuclear_fusion. Above 56, we have supernova nucleosynthesis: http://en.wikipedia.org/wiki/Supernova_nucleosynthesis.

Google (or arXiv) searches will give extensive references but off-hand I know of the seminal paper for stellar nuclear fusion (<56) by Burbridge, Burbridge, Fowler and Hoyle (1957): http://en.wikipedia.org/wiki/B2FH_paper. — Preceding unsigned comment added by 92.22.178.105 (talk) 21:33, 28 June 2012 (UTC)

Higgs
Should Higgs now be moved to the "recently solved" section? S Pat  talk 18:01, 4 July 2012 (UTC)


 * I would wait until a paper is published in a review journal like PRL.Dja1979 (talk) 20:01, 4 July 2012 (UTC)

Dark Matter
It is only *assumed* that dark matter exists in a galactic halo, it could also be located *inside* stars as an alternative solution. [Alan Lowey] — Preceding unsigned comment added by 195.59.118.104 (talk) 09:51, 16 August 2012 (UTC)

Some Suggestions
People with any suggestions (and what they are needed for) please place them below: Radical Mallard (talk) 20:11, 14 October 2012 (UTC)
 * Hi-Temperature Superconductor - needed for decoding information/energy passed between brain cells with no loss of signal for Thought identification, needed for Magnetic levitation transportation, needed for Plasma confinement Fusion power
 * Super Efficient Nuclear Fission Space-Engine - Needed to power the VASIMR space drive without a ridiculously massive sized heat radiator
 * Super strong lightweight filamentous fiber material - Needed for Space elevator

=
=====

Gravitational wave
Shouldn't this also be marked as solved? We now have institutions lige VIRGO, GEO600 or LIGO to collect data from Gravitational waves.
 * Have any of them reported detecting a gravitational wave yet? RJFJR (talk) 14:31, 22 October 2012 (UTC)

Ball lightning
I think that ball lightning should be listed. No one yet knows what they are: they've been observed and reported for centuries, but the cause of ball lightnings and therefore why they are formed and how is open to research. --Hartz (talk) 15:18, 2 November 2012 (UTC)

which problems qualify for this article
I'm guessing that any unsolved physics problem notable enough to have an entire Wikipedia article about it (not merely mentioned in passing in a Wikipedia article) is notable enough to be mentioned here. So I'm reverting some well-meaning deletes.

Or is there some narrower criteria that applies to this page? If so, what is it? --DavidCary (talk) 06:14, 29 January 2013 (UTC)

Malware Link Removal
-- Gary  Dee  18:22, 21 July 2013 (UTC)
 * Potentially Malicious Domain: (EXPLOIT, RBN Known Malvertiser IP 22)
 * hxxp://www.dailygalaxy.com/
 * https://www.virustotal.com/de/url/06f7d7c43c549e5e370a1e64d961bbbb9f4be55c29111d41e93ae9bb66489f23/analysis/1374427632/
 * JS/Exploit-Blacole.cw
 * https://www.virustotal.com/de/file/5ea1609b649e14ccfd84fec0d7e9d13cb0f885876f0ef5fae0407d23490ecddc/analysis/1374428349/
 * https://www.virustotal.com/de/file/192346fedd2cc52353f89fd93fe1da383b6fa8a969c4c27f1fa663d4a40c3ae4/analysis/1374428351/
 * https://www.virustotal.com/de/file/2656324fdda8179413cf416bd559e5f6f13864886a6d31907928e6334e64ebfa/analysis/1374428355/
 * https://www.virustotal.com/de/file/a9dc933ca440b54c82be1fc9a71df252cf738ca3d908814adc656d9ffcc7c6ed/analysis/1374428365/
 * https://www.virustotal.com/de/file/42430671c0fd1332eeb990373a1707da334520e2bae48d1dc9ee6df47b728125/analysis/1374428367/
 * https://www.virustotal.com/de/file/8eb65132b441b07193c467814570e2c0959ceff07e35149247f531dde514782f/analysis/1374428377/
 * REFERENCE: http://jsunpack.jeek.org/?report=49695ac9748fc84c3953dd8db54a661f52fd8be4
 * http://urlquery.net/report.php?id=3902995
 * SEE ALSO:
 * http://quttera.com/detailed_report/www.dailygalaxy.com
 * http://sitecheck.sucuri.net/results/www.dailygalaxy.com
 * http://www.UnmaskParasites.com/security-report/?page=www.dailygalaxy.com

Turbulence
Turbulence in Fluid Mechanics is often referred to as the last un-solved problem of classical physics. Why is it not listed here? — Preceding unsigned comment added by 37.104.112.71 (talk) 11:28, 12 August 2013 (UTC)

ALL OF THEM SOLVED, EASILY!
WITH THESE CORRECT LAWS OF THERMODYNAMICS, I AM CONFIDENT THAT WE, AS A HUMAN RACE, MAY WORK, EASILY, TO SOLVE ALL OF THESE PHYSICS "PROBLEMS":

1. Cold generates energy. Heat radiates energy. Cold multiplies. It cannot divide for it is the fulcrum of the universe which must extend to multiply. Heat divides. It cannot multiply but can be multiplied.

2. Every action must be preceded and followed by its equal and opposite reaction. Heat is the reaction of cold. Heat could not come into being save for the compressive action of cold, nor could it repeat itself without losing itself in basic cold.

3. Cold is static, unchanging and unconditioned. It eternally lives. Cold light is the basic ONE THING of this universe. Heat waves are dynamic, forever changing and dually conditioned. They are eternally living and dying to simulate life.

4. Cold light is the omnipresent basis of universal intelligence and energy. Hot waves of light, which we call matter, are a simulation of intelligence and energy. There is no intelligence or energy in matter.

5. Static cold and dynamic heat express their opposite energies at angles of ninety degrees from their axes of rotation. Cold retains its static, motionless condition along wave axes where motion ceases at points of maximum heat, while heat extends along equators to again expand as cold. This balanced interchanging completes the wave cycle.

6. Cold compresses. Cold multiplies cold to create heat. Heat expands to divide heat into cold. Varied pressures of heat constitute the octave color spectrum cycles and the octave chemical cycles of matter. Their varied wave lengths are the basis of our mathematics.

7. Long low waves of low potential and high frequencies constitute the invisible spectrum and low density gases while short high waves of high potential and low frequencies constitute the basis for high density.

These lessons may appear too simplistic -- they are not if you change your concept and open to the facts. They are brief for the information does not need take great and massive volumes for the method ALWAYS WORKS. Science now requires massive volumes upon volumes because the system rarely WORKS. You cannot enter incorrect data and expect results other than incorrect. If you dial an incorrect phone number -- you will never reach the one you wish at the correct number.

It is my hope that you give deep consideration of the consistency of these laws.

SOURCE: The One Light

CONTACT TO DISCUSS: Lightworker21@gmail.com

Please, if this post is incorrectly posted, according to "wiki" rules, and you must erase it, LET ME KNOW WHY it was erased through my e-mail address, so that I may post things correctly! Thank you. — Preceding unsigned comment added by 70.197.2.217 (talk) 23:17, 18 September 2013 (UTC)

70.197.2.217 (talk) 23:19, 18 September 2013 (UTC)

Dark Flow - disputed
According to the Dark Flow article, this is a very disputed subject whose existence is in doubt. Does it merit inclusion in this list? AadaamS (talk) 09:14, 4 September 2013 (UTC)


 * Absolutely. One of the proposed solutions is "it's an illusion". As long as there is no broad scientific consensus, the problem of explaining Dark Flow is unsolved. Paradoctor (talk) 11:05, 4 September 2013 (UTC)


 * When the controversy is over whether something is a problem to begin with (as opposed to an error), it is not the same thing as being an unsolved problem. "It's an illusion" implies that there is actually an phenomenon, which is precisely what is disputed. SamuelRiv (talk) 15:09, 7 September 2013 (UTC)


 * Looking at what I wrote, you're almost correct. Explaining Dark Flow presumes it exists, that's right. But that still leaves the problem of whether there is a phenomenon. This is a list of unsolved problems, not of unexplained phenomena. Otherwise, entries like "Future of the universe" would have to go. It might be useful split the list into main sections like "unexplained phenomena", "contested phenomena" and "theoretical problems". Paradoctor (talk) 17:06, 8 September 2013 (UTC)
 * The problem of explaining Dark Flow doesn't exist yet. That problem will only come into existence when the phenomenon has been proven to exist in the first place. Sub lists is a good idea. AadaamS (talk) 06:59, 9 September 2013 (UTC)
 * It seems that most editors agree that Dark Flow isn't an unsolved problem, it's a disputed phenomenon so I delete it from the list AadaamS (talk) 13:18, 30 September 2013 (UTC)

Ball lightning
Why this entry was removed? Undeleted. Raoul NK (talk) 12:38, 14 October 2013 (UTC)

I removed it because it is not a definable physical phenomena. The Ball_lightning  entry only offers anecdotes to its existence. There is no concrete definition of what ball lightning is, and there is no verifiable data for it. Its existence is questionable, see: http://www.straightdope.com/columns/read/2562/does-ball-lightning-really-exist http://skeptoid.com/episodes/4192

While "what is ball lightning?" is an unsolved problem, it is not one of physics, yet. Because there is no definition of what ball lightning actually is, and there is no hard data showing its existence. User:cowlicks(talk) 12:27, 22 November 2013.

The Backreaction Conjecture
I think that this open problem should be added to the cosmology section. There are currently quite a large number of debates about it in the community of cosmologists. The question is the following: is the apparent acceleration of expansion of the Universe a result of the backreaction of matter (large scale structures) on the space-time metric ? User:vreverdy 00:15, 7 December 2013.
 * Hi vreverdy! I think it could be added - or maybe it's better to create a new tab for conjectures? It would be wonderful if you could give a few details about how it behaves in GR versus Newtonian gravity and the problems that result. (1995: Backreaction is rigorously shown to reduce to a boundary term in Newtonian gravity - Buchert and Ehlers; 1999: Backreaction is shown not to reduce to a boundary term in GR - Buchert). I checked and there seems to be no page for relevant conjectures in physics - maybe we could do that and link it here as well? There are plenty of interesting conjectures and a separate page provides enough space to explain why were they created.Almaionescu (talk) 17:16, 12 December 2013 (UTC)

Mathematical Physics
Should a section be added on unsolved problems in mathematical physics? Jj1236 (talk) 04:40, 9 December 2013 (UTC)
 * Great idea! Do you need any help?Almaionescu (talk) 16:56, 10 December 2013 (UTC)
 * Thanks! I know rather little mathematical physics, and hope an expert will step up to fill this role.Jj1236 (talk) 01:41, 14 December 2013 (UTC)
 * I think we can start building up a list with the most known things, like the Navier-Stokes equations and build up from there. I can try to compile something in my sandbox (and I'd appreciate if you could take a look). When it's ready we can ask for peer review, just to be on the safe side. Based on length we can add it here or create a new page and link it to this one. What do you think? Talk Alma 15:35, 14 December 2013 (UTC)

Cite! - or it didn't happen
I suggest not to remove entries from this page. It is of public interest to know how any of the problems were solved, if this was the case. Instead of removing entries, please move them to the 'Problems solved in recent decades' tab along with citations from relevant scientific publications stating the problem was solved and describing the generally accepted resolution. Since it is a difficult field, I would suggest that conjectures, even from prominent scientific figures, do not suffice for considering a problem closed.Almaionescu (talk) 16:57, 10 December 2013 (UTC)


 * This policy could work if only experts in the relevant fields added problems. Unfortunately sometimes a problem gets added that does not belong on this page.  In that case, the best policy is to remove it.  For example synaptic plasticity is not a single unsolved problem in physics. 1) It is not singular: Multiple mechanisms are involved, and you can read all about them on their own wikipedia article.  2) It is not an unsolved problem: See the 20+ citations on the synaptic plasticity article for a very small sample of relevant research.  Open questions remain, but none are so general as the blurb here falsely implies.  3) It is not problem in physics: Just because physical stuff is involved does not make it a physics problem.  Economies are made out of physical stuff, but inflation is not a physics problem.  High-level cognition falls into the domains of cognitive science, neuroscience, and psychology.
 * A minimum set of criteria for inclusion on this page requires positive answers to, 1) Is it physics? and 2) Is it an unsolved or recently solved problem? Further criteria are also usually employed: 3) Is it a major problem recognized as such by the scientific community?  4) Is the problem well articulated, such that it could be solved.  No one person is qualified to judge all cases, and we work together as a community to evaluate inclusion or exclusion of problems.  Thank you for your help with this!Jj1236 (talk) 01:39, 14 December 2013 (UTC)
 * Ok Jj, I removed both axon guidance and synaptic plasticity on account of not being unsolved. From a reductionist perspective they may be physics in the end, but so is everything else. I think we should put the neural network problem somewhere (maybe include in open mathematical physics?) because it's very interesting as a triality between physics (the beneficiary), biology (the model) and math (the descriptor) and an open field of study with implications in high dimensional data models. What do you think? We've still got physical information which is the same as quantum information and linked to the black hole problem but not reducing to it (paraphrasing Lee Smolin, Time Reborn, how does an electron know what it is? or as per the wiki page, how is this information stored as a state? - both being legitimate questions), age-metallicity (maybe I should rephrase it?) and asymptotic confinement. Let me know Alma 17:04, 14 December 2013 (UTC)


 * Hi Jj, I just saw this article about how axon guidance is completely solved http://medicalxpress.com/news/2014-01-mystery-nerve-impulse.html . Can you help inserting the research into the axon guidance main page? You seem to be more familiar with the subject than I am :) Alma (talk) 13:59, 10 January 2014 (UTC)

wikipedia incomplete
We need to gather together the top wikipedia editors and have them fill in all the answers to these questions. There's only like 5 answer filled in so far. Someone should put in a hyperlink to the wikipedia articles that have the correct answers for these. — Preceding unsigned comment added by 174.59.92.42 (talk) 07:52, 10 January 2014 (UTC)
 * Given the answers are not known as the title suggests "unsolved problems" -> no we needn't do that. There are no answers known and accepted by the scientific community. Physics is incomplete. Alma (talk) 09:31, 10 January 2014 (UTC)
 * There is no spoon. Paradoctor (talk) 14:58, 10 January 2014 (UTC)

Remove ball lightning from the list?
Recently ball lightning has been observed and had its spectra analyzed for the first time. It's caused by silicon in the soil being vaporized and subsequently oxidized. 1 So shall we move this to recently solved problems? ScienceApe (talk) 06:55, 24 January 2014 (UTC)
 * I'm not convinced ball lightning is or was a problem of physics to begin with; more like a problem of meteorology. Was the tornado a problem of physics before science figured it out?  -Jord gette  [talk]  01:44, 25 January 2014 (UTC)
 * It was a problem because it was so infrequent and relied upon anecdotes for the majority of its evidence. Before the recent study and spectral analysis, many physicists even denied it existed at all due to their transient and rare occurrences. Tornadoes weren't a problem in the same sense because no one was skeptical of their existence, people knew they existed because they are kinda hard to miss. ScienceApe (talk) 22:21, 25 January 2014 (UTC)

Red links
We have some redlinks in this article which should be fixed or at least reviewed. RJFJR (talk) 02:39, 9 June 2014 (UTC)

Planar Galactic spheroid
See this edit. I think think this merits inclusion as soon as the relevant content is in shape. Paradoctor (talk) 23:25, 26 July 2014 (UTC)

Dwarf galaxy problem
Should it be included? Paradoctor (talk) 23:10, 26 July 2014 (UTC)

The dwarf galaxy problem is really one particular problem with some versions of Cold Dark Matter theory, rather than a problem related to dwarf galaxies per se.Ohwilleke (talk) 02:10, 29 August 2014 (UTC)

Remove quasars from the Solved list?
The article says that quasars are now generally understood. Yes, the current view is that they are galactic cores where the enormous energy output results from matter falling into a massive black hole in the center of the galaxy. However, observations show that they can vary their light output daily, suggesting a quasar diameter constrained by a light-day's distance, and that would limit their radius to just more than four times the distance of the Sun to Pluto, far to miniscule to represent a galactic core. Perhaps healthy scientific skepticism would keep quasars, for now, off the Solved list. Thoughts? Bob Enyart, Denver KGOV radio host (talk) 18:46, 28 November 2014 (UTC) Bob Enyart, Denver KGOV radio host  (talk) 02:38, 23 February 2015 (UTC)

Typo in dimensionless constants
Is this a typo: What is the minimum number of dimensionless physical constants from which all other dimensionless physical constants can be derived? Shouldn't that be minimum number of dimensionfull physical constants? Erwin (talk) 20:38, 6 July 2015 (UTC)
 * The word you mean is "dimensionful" (one "L"). But I think it should say "dimensionless". I would think there are other dimensionless physical constants that can be derived from the minimum set and then from the set of all dimensionless physical constants all the dimensionful constants are derived, although the question leaves that part out. Richard-of-Earth (talk) 07:39, 7 July 2015 (UTC)

What about mathematical physics?
There are some unsolved problems in mathematical physics: Davius (talk) 19:53, 15 August 2015 (UTC)
 * 1) A non-perturbative approach in QCD.
 * 2) A mathematical rigurous and general definition of Feynman Path Integral (see Mathematicla problems in Path Integrals)
 * 3) There is a completely rigurous mathematical treatment of renormalization?
 * 4) What kind of mathematical object is needed for defining the space of all possible loops in a Loop quantum gravity theory (certainly, a smooth Lorenzian 4-variety is not enough!)

Fast Radio Bursts (FRBs)
I find it strange that FRBs aren't even mentioned in this article. I did a quick search, and I couldn't find anything. I would add them, but I am worried that there might be some reason for them not being included in this article. — Preceding unsigned comment added by JNeutrino (talk • contribs) 18:16, 18 January 2016 (UTC)

✅ Thanks, Paradoctor (talk) 18:44, 18 January 2016 (UTC)

Anderson localization of light
Probably one of the most important unsolved problem is the Anderson localization in optical systems. It was proved that in electronic systems, 1D and 2D optical systems light can be localized. However in 3D systems there is no analytical, numerical or experimental evidence. Inside of the electrodynamics community, this is considered the most important open problem. — Preceding unsigned comment added by 150.244.7.117 (talk) 10:41, 11 February 2016 (UTC)

missing item? equivelence of inertial and gravitational mass
i wasnt sure enough to edit the list, but as far as i know the equivalence of gravitational mass and inertial mass has no (proven) explanation and is a fairly fundamental unsolved problem? If someone else is sure please add it — Preceding unsigned comment added by 2.25.113.67 (talk • contribs)

And relativistic mass is a complication. — Preceding unsigned comment added by 100.37.208.238 (talk • contribs)


 * IMHO it is not the case that (to quote the header) "existing theories seem incapable of explaining a certain observed phenomenon or experimental result", since general relativity (an existing and well-established theory) takes the equivalence to be axiomatic, and is therefore in agreement with the observations and experimental results about mass. Rolf H Nelson (talk) 06:17, 6 April 2016 (UTC)

Astrophysical Jet process possibly solved
See the Wiki article Astrophysical jet and its Talk section. If nuclei in the core of a neutron star collapse and matter is efficiently converted into energy an obvious candidate for the basic process is: Proton --> positron + 938MEV. Or neutron --> positron + electron + 938MeV. Either process results in a 460MeV max positron-electron beam. This is for a neutron star but probably applies to so called "black holes" too. Many black hole theorists probably won't like this but positron-electron jets with a maximum of 450MEV will tell the tale. Note if positron-electron jets are accelerated magnetically outside the star there is no reason they should be limited to under 450MeV.

The situation could be somewhat more complicated. In a collapsing core after nuclei collapse occurs, positrons and electrons should collapse, leaving just neutrinos etc and intense gamma rays. I don't think this happens in a neutron star but it could happen in a supernova. As this stuff is blown away from the star some of it could recombine again to positrons and electrons but if their density was low their energy could be greater than 450MeV. At very high energy the positron-electron density might be quite low! Regardless, even if the beam were mostly gamma rays, the beam energy ultimately comes from collapsing nuclei releasing 938MeV.

Additional jet conclusion: A neutron star over 2 SM ejects all accreting mass because collapsing nuclei in the core release 938MeV (on top of the gravitational energy), resulting in the jet. Probably a black hole is a compact star of perhaps 1.2 Schwarzschild radius which ejects most of the accreting mass in a similar process 100.37.208.238 (talk) 23:01, 6 April 2016 (UTC)BG

Adding protein folding problem to biophysics
The protein folding problem is quite possibly the most significant problem in biophysics and I'm surprised to not see it listed. Jdazzle95 (talk) 19:54, 18 April 2016 (UTC)

Editing / phrasing (for all categories)
In Color Confinement: "Why has there never been measured a free quark or gluon" Actually, nowadays top quarks are routinely observed standalone, decaying before having time to hadronize. The problem of confinement still holds but now it is known for a fact that there is not some hidden principle dictating that quarks be bound a priori. If one day I feel eloquent I'll change this appropriately, unless someone who can do that better gets there first :) — Preceding unsigned comment added by 110.76.103.141 (talk) 15:25, 6 June 2016 (UTC)

Inclusion criteria: should we bar items that aren't "major unsolved problems in physics"?
The article identifies the scope as "major unsolved problems in physics", but most items aren't sourced as such, and many of them seem dubious matches to that subjective criterion. The newest addition, 750 GeV diphoton excess, fits the scattershot pattern of existing entries. Some possible alternatives to fix it are:

1. Agree on the Talk page that the scope is "Unanswered questions in physics". Anything reported in the mainstream science media is suitable for inclusion.

2. Scope is "Major unanswered questions in physics". If there's disagreement about inclusion of an item, the includer needs to provide a citation that it's considered a major unanswered question in physics. This would be my personal preference because it's easy to determine what's suitable for inclusion.

3. Scope is something like "Major unsolved problems in physics", which is a higher bar than (2). Only robustly-observed phenomena currently considered problematic (that is, has no satisfactory explanation consistent within any mainstream model) are included. "What is the shape of the universe" would be unsuitable for inclusion as there are too many, rather than too few, reasonable models that fit existing observations. The diphoton excess would IMHO probably be unsuitable because, again, there are currently at least two non-problematic explanations, either "the LHC analyzers messed up" or "we will have to add a (possibly otherwise-unremarkable) 18th particle to the Standard Model, but we don't yet have enough information to determine much about it". I'm not sure how this would work in practice. This could make for a really interesting article (especially if each entry briefly touched on *why* the problem is puzzling), but it might be a pain to come to consensus on which items make the cut. Rolf H Nelson (talk) 04:06, 20 July 2016 (UTC)


 * Can you maybe give an example of a citation that would sufficiently satisfy everyone that an unsolved problem or an unanswered question is "major," because, as you said in your third point, your idea might be difficult to make work in practice. I do understand what you are saying, at least in general, but I don't really agree with the "problems" idea because it seems to me that that might narrow the focus of the article too much. JNeutrino (talk) 10:50, 20 July 2016 (UTC)
 * Nothing ever satisifies everyone, but something labeled as 'major' in any mainstream media pop-science list should be sufficient. Rolf H Nelson (talk) 02:29, 22 July 2016 (UTC)


 * We are an encyclopedia, so (1) is the way to go. When the list becomes too big, we can WP:SPLIT along whatever lines are convenient. The topic is certainly notable.
 * "Problem" and "question" are used pretty much interchangeably, so I'd be ok with either.
 * (2) "easy to determine what's suitable" I don't see how (2) would be easier than (1). In both cases we rely on the literature as inclusion criterion.
 * (3) "interesting article" I see no problem in starting with an interesting section, which can be split out when it becomes convenient.
 * Paradoctor (talk) 16:07, 20 July 2016 (UTC)

Sterile neutrinos and reactor antineutrino anomaly
Hi all, should the reactor anomaly and sterile neutrinos be included in the list? it can fit after "Neutrino mass" and read:

Sterile Neutrinos Are there any neutrinos not carrying a weak charge? Do they participate in the neutrino oscillations?

Reactor Antineutrino Anomaly How can be the reactor antineutrino anomaly can be explained? — Preceding unsigned comment added by Troyaner (talk • contribs) 18:39, 14 August 2016 (UTC)

What about other fields of science
It would be interesting to add corresponding lists of unsolved problems in geology, chemistry, biology, medicine etcetera. These fields of science are sometimes related to physics. OliverBear (talk) 21:13, 8 November 2016 (UTC)


 * See Lists of unsolved problems for a list of list of unsolved problems by field. This article is specifically the Physics list.  RJFJR (talk) 21:17, 8 November 2016 (UTC)

Generalized Anderson Localization
This is one of the biggest problems in condensed matter physics. Huge efforts have been made in the last 30 years in order to have a theoretical or an experimental evidence of the generalized Anderson Localization phenomenon. — Preceding unsigned comment added by 158.227.0.241 (talk) 14:42, 23 January 2017 (UTC)

Eddington's time-arrow - no need for revert
On this revert. I was careful in my edit[s], I believe, to not say "solved" (only "probably" in edit summary). Didn't even mention the Richard A. Muller's Now theory ("4D Big Bang", not just 3D..). comp.arch (talk) 20:18, 29 March 2017 (UTC)
 * The problem is considered solved when a theory is broadly accepted and is no longer a topic of research or inquiry. As far as I know it is still discussed in the literature as an unsolved problem. Do you have a reliable source showing that Muller's theory is broadly accepted as a solution to the problem?  -Jord gette  [talk]  20:22, 29 March 2017 (UTC)

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Wow! signal may be solved
We believe it was caused by the comet called 266/P Christensen. This view appears to be espoused with some confidence. I just don't want to make an edit to the list without confirming with people. Penrose Delta (talk) 18:19, 9 June 2017 (UTC)


 * Good stuff, thanks. This may indeed be sufficient to consider the mystery solved.  -Jord gette  [talk]  19:44, 9 June 2017 (UTC)
 * Here's a refutation: http://blogs.discovermagazine.com/d-brief/2017/06/08/closest-thing-to-aliens-not-aliens/#.WTr-JDCoOZ8  -Jord gette   [talk]  20:17, 9 June 2017 (UTC)
 * Not that this is an RS, but it's looking dodgy. https://www.reddit.com/r/Astronomy/comments/6ganha/no_the_wow_signal_was_probably_not_caused_by/  -Jord gette  [talk]  21:25, 10 June 2017 (UTC)

Duplicate entries
The entries "Axis of evil (cosmology)" in "Cosmology and general relativity" and "Large scale anisotropies" in "Astronomy and astrophysics" are about the same problem(s). IMO the latter should be merged to the former. Thoughts? Paradoctor (talk) 22:17, 26 June 2017 (UTC)


 * Not an expert on this, but I agree that, unlike, say, the Wow! signal, the curiosity of this entry lies in its cosmological implications. Daß &thinsp; Wölf 00:52, 28 June 2017 (UTC)

Smart Stuff for the Layman
I find this kind of stuff interesting, but always come accross a similar problem when reading pages about science and or mathematics, etc. And that is that nearly all the articles are written in a way that, unless you are a scholar of said subjects, i cant always understand. I think there should always be a back to the future type explanation on these kinds of articles, and what i mean by that is, in the film back to the future 2, marty leaves the future and heads back to 1985, but upon arriving finds that things are very different due the fact that biff went back to 1955 and changed his own fate, thus changing martys present. Doc explains that something caused a temporal distortion; somewhere in the past, the timeline skewed off into an alternate reality. On a chalkboard, he draws the normal timeline and the alternate timeline to show marty in laymans terms what has happened. basically my point is, that some kind of laymans explainers for subjects in highly intelligent articles would help a hell of a lot. and would probably get a lot more people interested in reading about those subjests, as opposed to getting so far in, and then giving up when they get to a part that they just cant understand. does anyone else think this is a good idea, as most of the time, they seem to be written on the aasumption that whoever is reading the article is going to know what everything in it means. when in reality it could just be some 10 year old kid that wants to read about quantum mechanics to see what it is. — Preceding unsigned comment added by D0S81 (talk • contribs) 19:24, 29 October 2017 (UTC)

Why does time have a direction?
Because the present was first, then came the past before the future. Do I really need a source for this? This is fundamental physics. God help the children! — Preceding unsigned comment added by 162.254.64.65 (talk) 20:54, 29 October 2017‎ (UTC)


 * The time has direction because the change in time is equal to the product of change in energy and inversely to the constant energy the factors gives the direction of time but we cannot go to the past and future because the universe uses its ingredients in the form of product of change in energy and constant time and inversely constant energy Mohammad jahanzaib (talk) 14:01, 31 October 2017 (UTC)


 * "Do I really need a source for this?" Maybe WP:NOTBLUE will answer your question. Paradoctor (talk) 15:07, 31 October 2017 (UTC)

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