Talk:Unsolved problems in physics

From Wikipedia, the free encyclopedia

	This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.	Physics Portal
B	This article has been rated as b-Class on the assessment scale.
Top	This article is on a subject of top importance within physics.
Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.

What about Bell's theorem and Allais effect which aren't exactly unsolved problems, but do need to be categorized as something, other than "general physics"? linas 16:36, 1 May 2005 (UTC)

---

I believe that many of the superstring theories should be there, seeing as how many of them are unsolved as well.

Those theories are just explanations, not observable problems. Tzarius 05:29, 13 July 2005 (UTC)

Contents 1 Galaxy rotation problem 2 The template 3 matter and antimatter 4 Contrived questions 5 gravity waves, accelerating universe 6 Black holes 7 Zero point energy 8 Spintronics, quantum computers 9 More Basic Problems 10 Deleted 11 Motion 12 Saturn 13 Section Titles 14 Cold Fusion?! Ball lighting ? 15 Why you deleted? 16 Corona of the sun 17 Pioneer anomaly: 18 problem 19 Quantum Teleportation 20 Phenomena or established occurrences 21 Charge 22 Broken external link 23 Accelerating universe 24 Heavy bias in favor of particle physics

[edit] Galaxy rotation problem

To claim that this is a separate problem from dark matter is strange indeed. I am going to remove it again, but please let me know if anyone has any objections and from whence they originate. Joshuaschroeder 06:34, 15 May 2005 (UTC)

Ohwilleke 00:14, 30 July 2005 (UTC) Joshuaschroeder removed a MOND reference arguing that it was fringe science. In fact, it has been the subject of about a two hundred peer reviewed journal articles [1] since the theory was forumulated, some as recently as 2005, by PhD physicists in respected universities and institutes. While I agree that it is a minority viewpoint, it is hardly fringe science. Indeed, it has a far better record of empirical success than supersymmetry, string theory, LQQ or any other number of theories that are in the Wiki, and given that this is a NPOV Wiki, it is not appropriate to wipe out references to all non-fringe minority views. To be really neutral, one ought to be talking about the Galaxy rotation problem and the lensing issues, rather than dark matter per se, as the former are phenomena which are not fully explained (dark matter is not a complete theory as it lacks a discovered particle or an explanation for why it is distributed as it is) while the latter is merely a theory to explain these phenomena.

MOND is minority and is generally advocated by a very small handful of scientists, its successes notwithstanding. The major question is "What is Dark Matter?" With apologies to the MOND people, I think this parametrizes the question very well. If it turns out that Dark Matter is just a gravitational theory effect, well then the answer will be "Dark Matter doesn't exist". Placing it squarely with the galaxy rotation problem is a bit limiting too since there are more observations that dark matter/MOND must deal with than just rotating galaxies. --71.57.90.3 21:05, 19 May 2006 (UTC)

[edit] The template

The template on this page is kind of a self-reference. Anywhere else we can put it? Andre (talk) 00:28, May 30, 2005 (UTC)

Your right, I think this talk page is a good home for it. - SimonP 03:06, Jun 10, 2005 (UTC)

[edit] matter and antimatter

if there are the same amount of antimatter and matter, the universe would just be left with annihilation between matter and antimatter everyday, and at the end, radiation and energy would be the only things left in the universe.

Not necessarily. Matter and antimatter require very close contact before they can do anything. Stars and galaxies are really, extremely, very far apart. Tzarius 05:26, 13 July 2005 (UTC)

It would annihilate against the interstellar medium. Not that this has anything to do with the article... -- CYD

In fact, this is the basis behind a whole field of cosmology, as well as the exploration of potential CP violation - i.e., the possibility that certain particles lack antiparticles and thus do not anihilate. -- AJA

or are they?

[edit] Contrived questions

Some of the question formulations in this article seem fairly contrived and forced. For example:

• Fusion power: Is it possible to construct a practical nuclear reactor that is powered by nuclear fusion rather than nuclear fission?

This doesnt seem like one of the great unanswered questions in physics at all. There are plenty of examples of fusion reactors found in nature, they are called stars. Making a device which harnesses a well-known process to physics falls far more into the realm of engineering than great unanswered questions.

Furthermore any question in the form: "Is it possible to construct.." has only two possible answers: YES and NO. Supposed the answer was YES. Are any scientists now satisfied with that answer or the question? The actual problem is of course not if it "is possible to" solve something (which is just yes/no) but the solution itself.

Here's another example:

• Grand unification theory: Can the laws of physics be unified?

Is that really a helpful entry? It doesnt address any real problem and seems like the question formulation was a forced after thought to the subject matter. As is typical of Wikipedia, the content is clearly symptomatic of many small disjoint additions. I think this page needs a rewrite listing fewer problems and a paragraph giving each a brief background of the current situation and from where the problem originates. Here is the format that I had in mind.

Magnetic Monopoles Current equations in electromagnetic theory treat the Electric Field and Magnetic Field symmetrically except for the presence of an electric charge and the absence of a magnetic charge. The existance of a magnetic monopole would give an elegant balance to these equations and is predicted by several grand unified theories. So far a magnetic monopole has never been experimentally observed.

No need for a literal question to give rise to the problem. 129.42.208.182 20:23, 19 July 2005 (UTC)

I don't think the page is in nearly as rough shape as you suggest. It is nice to have a reasonable, succinct list with links to fuller articles.

While I agree with your criticism of the wording of the fusion reactor question, understanding the properties of plasmas in the laboratory (or indeed, astrophysical plasmas such as active galactic nuclei, is a major field of research in physics – not engineering! – and ought to be included in some form.

As for the grand unification theory, this is symptomatic of the current state of high energy physiccs. There are a number of questions, ranging (along the axis from gravity to particle physics) from quantum gravity, through string theory, through supersymmetry, through grand unification theory, through proton decay, through the standard model to quantum chromodynamics. All these questions are closely interrelated, although they all probe the same problem, which is that we don't understand quantum gravity/high energy physics/non-perturbative gauge theory. –Joke137 18:35, 20 July 2005 (UTC)

[edit] gravity waves, accelerating universe

User:CYD reverted some recent edits to the gravity wave and accelerating universe problems. I like them in their current version because:

• For the accelerating universe, we know our universe isn't supersymmetric, and we know that the scale of supersymmetry breaking is high enough that it is not clear that supersymmetry helps at all to keep the cosmological constant small.
• For gravity waves, see above.

Please discuss your changes on talk, if they were intentional. –Joke137 18:26, 20 July 2005 (UTC)

[edit] 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)

[edit] Zero point energy

Would zero point energy be an example of an Unsolved problem in physics even though it is considered a pseudoscience? (Honest question) - UnlimitedAccess 09:01, 10 August 2005 (UTC)

I don't think so. It seems more of a conjecture as a possible result of a particular theory, like 'negative mass'. It might be real, but it hasn't been encountered and it doesn't really affect anything besides theory that posits it. Tzarius 09:14, 11 August 2005 (UTC)

[edit] Spintronics, quantum computers

Is "is there a way to use this (known real) phenomenon in a device" really an unsolved physics problem? At best, it sounds like an unsolved engineering problem. Ken Arromdee 20:59, 13 September 2005 (UTC)

it is a physics problem in that the issue facing the "quantum computer scientist" is whether or not such a construct would be allowed under the rules of quantum mechanics and, if so, would be useful as a computer (in the tradiational sense). For example, it is not possible with a quantum computer (the abstract, as of course no such device has been constructed) to do a simple addition operation; the probabilistic nature of quantum states means that there are no deterministic binary operations in these systems. However, the device might be useful for (the standard example) encryption, since it is impossible to read a message incrypted in a quantum bit without the recipient knowing that it has been read. --AJA

I don't believe that this is still an "unsolved problem." A seven-bit quantum computer has been constructed that could factor the number 15 using Shor's algorithm. This is not an unsolved physics problem--it is a solved engineering problem. --Sxeraverx 15:57, 21 May 2006 (UTC)

[edit] More Basic Problems

There are more basic laws of physics that have been discovered, accepted, and built upon, but never understood. Why are they not mentioned?

The list of Conservation law and Newton's Laws of Motion are examples of these.

For example, there has never been an explanation for the Newton's 3rd Law: Law of Reciprocal Actions which states that, for every force, there is an equal and opposite force. This is the fundamental principle that allows rockets to launch since, to lift the mass of a rocket, you must expel a higher amount of matter (fuel) in the opposite direction.

But...why is this so? Why must there be an opposite reaction? And the answer that is often returned from physicists is "So there's conservation of momentum." This is circular logic and an example of many unexplained phenomena in physics that should be mentioned here.

These are much more basic questions that have never been explained other than stating that "They simply are." Captainks 17:25, 21 October 2005 (UTC)

It should be noted first off that physics is, in essence, an empirical science; although there is a fad nowadays to try and find a holistic, unifying explanation for all observed phenomena, it must be remembered that ultimately any such explanation relies on some set of axioms, some group of statements that must be taken as true without deeper explanation, even if they are as simple as "matter exists." However, as to the question just raised, these "simpler" laws of physics suffer from quite a common misrepresentation: they are described as being true on all levels, for all objects, at all times. Unfortunately, this is misleading. The law of conservation of energy, for example, is, on almost all levels, true; however, when certain particles decay, there is a brief period of time during which there exists an object called a W boson, which possesses a very high rest energy, much higher than the original decaying particle. In other words, this high-energy object appears out of nothingness, briefly violating the conservation of energy, then shortly thereafter returns to nothingness, restoring the balance.

For a less esoteric example, Newton's Third law is true for forces of all types. Ultimately, the law underlying this is the conservation not of momentum, but of energy (although conservation of momentum is usually used on macroscales because energy can sneak away as thermal, chemical and electromagnetic energy during physical reactions). Ultimately, if we accept the axiom, integral to physics, that there is a fixed amount of energy in existence, then Newton's Third Law will follow for any isolated system.

So in summary, the more basic problems you've noticed are in fact little approximations of convenience; they are called laws because they are so very, very often true. The whole construct of physics is based on observations, so ultimately we can't ever provide a complete logical explanation without reference to some observed 'fact,' those axioms I keep mentioning; those are the things that "simply are," without which it becomes impossible to attempt to understand the physical world. --AJA

Newton's Laws? Easy -- the principle of stationary action. The principle of stationary action? Easy, Feynman's path integral formulation. As stated above, we will always explain one thing in terms of a (hopeuflly) simpler (in terms of elegance, probably not mathematics) theory. But there will always be some fundamental assumption, even if that is "the universe has physical laws". Masud 14:56, 24 December 2005 (UTC)

I think the contributors here miss a central point. Conservation laws result from symmetries. While the statement that Newton's laws can be encoded from the principle of stationary action is correct, the real issue concerns the symmetries the action possesses. For example, the conservation of momentum results from translational invariance in the underlying action. Sometimes symmetries that appear exact, on further inspection or not. Sometimes it is useful to postulate an approximate symmetry and examine the interactions that violate this symmetry through the violation of the predicted conservation law. In this case the conservation law is only approximate. As we probe higher energies, violations of certain symmetries can appear, rendering the conservation law associated with it invalid. Sometimes higher energies can reveal new symmetries that were absent at the lower energy scales and give us new conservation laws. There are many examples of this in physics. What the high energy physicist seeks are the symmetries of new interactions that dictate the dynamics involved.

[edit] Deleted

I've deleted the black hole "problem". Black holes have been identified as real for some time now.

The black hole line was put in there by User:Ems57fcva, who on his own page claims that he strongly dislikes black holes, and who is working on a new theory that changes Einstein's theory of relativity while protesting that he is not doing so--in short, he's a crackpot whose crackpot theories motivate him to over-emphasize scientific uncertainty about black holes. Which itself doesn't mean the line is wrong, but it certainly does explain it.

Scientists may disagree somewhat about unobserved properties of the objects that have been identified as black holes, but those disagreements aren't about qualities so fundamental that they are disagreements about whether the objects are black holes at all.

It's true that nobody has seen a singularity, but the fact that nobody has actually seen something doesn't make its existence an unsolved problem, since there's little dispute that it in fact exists. It's like saying that whether the Earth has a metal core is an "unsolved problem" because we haven't actually seen the core, just deduced its existence. Ken Arromdee 23:28, 27 October 2005 (UTC)

[edit] Motion

I've also deleted the motion line. There is no serious dispute among scientists about what causes the perihelion advance of Mercury; that is well known as being a consequence of Einstein's Theory of Relativity. Similarly, relativity says that there is no such thing as absolute motion; there is no serious dispute about that either. Describing these as "problems" is wrong and is probably yet another crackpot taking aim at Einstein. Ken Arromdee 02:39, 1 November 2005 (UTC)

Reverting most of that change. Here we go again.

• Einstein said that absolute motion doesn't exist. Claiming that whether absolute motion exists is an "unsolved problem" is crackpottery claiming that Einstein is wrong.
• Newton's laws say that an object in motion remains in motion. Moving stars need no power source, and even Einstein didn't say that they do. Claiming that the power source of moving stars is an unsolved problem is more crackpottery.
• There is little dispute among scientists today that the objects we call black holes are black holes, even if we can't see inside one. It is only an unsolved problem to cranks, who have their own strange theories which are contradicted by scientific acceptance of black holes.

Ken Arromdee 17:43, 12 November 2005 (UTC)

• According to the platonic philosophy, relativity cannot be wrong. IMO modern "physics" is pure math with very little reality in it. --QuantumDynamo 06:26, 13 November 2005 (UTC)

And how useful your opinion is... -- CYD

[edit] Saturn

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

No.

[edit] Section Titles

Shouldn't some of the points in "Theoretical ideas in search of experimental evidence" rather be in "Phenomena in search of an explanation" ? E.g the ones about Quantum Mechanics or QCD. Alternatively, one could introduce a new heading " Theories in need of expansion" or similar.

Feegle 18:35, 20 January 2006 (UTC)

[edit] Cold Fusion?! Ball lighting ?

Cold Fusion? At least in high energy physics that's treated as a plain joke. It has been proved that cold fusion doesn't occur. Why is it here? Is it taken seriously by any scientist? —The preceding unsigned comment was added by 201.13.252.228 (talk • contribs).

Below is a copy of the debate in Talk:low energy nuclear reaction. The issue is still unresolved, so any input is appreciated. Pcarbonn 22:17, 13 May 2006 (UTC)

Deglr6328 deleted cold fusion from the list, saying "when it is not even agreed upon whether a purported phenomenon exists within the realm of actual physics it is not proper to frame it as a question physics has to solve". I responded by saying: "The DOE report says that this is a valid area of scientific investigation". (see cold fusion).

Deglr6328 removed the "unsolved problem in physics" in low energy nuclear reaction on the ground that "DOEs views on the matter are utterly irrelevant. framing the question in this manner gives implicit approval of the question's status and respectability when there is none at all".

The question of the relevance of DOE's view was heavily debated on the cold fusion page (see Talk page, "DOE policy"), and eventually DOE's view was kept in the intro of that article. The reasons for giving it such a prominence are the following: DOE is the last (and probably only) published scientific review of the matter, and DOE's 2004 review was largely quoted by the popular and scientific press, including Nature. Actually, DOE's review is by far the most quoted review on the subject, by skeptics and LENR researchers alike. If you still believe that DOE's view is irrelevant, I would suggest that you raise the issue in the talk page of cold fusion.

The phrasing is : "What is the explanation for the apparent production of excess heat and helium in palladium metal when it is saturated with deuterium?". I have explicitly added the word "apparent" to express that it is not recognized by everybody. Also the question is very open, so that the source could be chemical, nuclear (or even fraud). I'm open to change in the phrasing, but I believe it is pretty good already.

Pcarbonn 06:26, 13 May 2006 (UTC)

Another evidence that cold fusion is a valid scientific research area is that, in March 2006, the American Physical Society held a session on cold fusion in Baltimore (See 2006 APS March meeting [2]). Pcarbonn 14:08, 13 May 2006 (UTC)

Deglr6328 has removed the "unsolved problem in physics" again, saying "no convincing evidence presented". Please explain why the evidences above are not convincing ? Could you give convincing evidence that DOE's view are irrelevant ? That there is no status and respectability to the question ? Please engage in the debate to justify your action. Pcarbonn 21:45, 13 May 2006 (UTC)

I guess the question is about what we want to include in this "Unsolved problem in physics" article. Should ball lighting be part of it, although "it is not even agreed upon whether it exists within the realm of actual physics" (the article says "Scientists disagree on whether it is a real phenomenon.") ? If yes, then I do not understand why cold fusion would not be part of it too, especially if it is a recognized area of research by the APS and by physicists who made the effort of reviewing the current status of the issue (such as the DOE reviewers) (which is not the case of ball lightning). Any input welcome. Pcarbonn 22:17, 13 May 2006 (UTC)

[edit] Why you deleted?

Hi! Why you are deleted my contributions about the Earth precession? Thank you for response. abel 22:11, 1 April 2006 (UTC)

[edit] 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.

(- 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)

[edit] Pioneer anomaly:

I suggest this should be deleted as it's a local engineering problem, not a problem of fundamental physics. Comments?

A local engineering problem ? If it was just that, there would not be so much interest in this topic. So I believe that there is enough evidence that some scientists believe it could be more than that, including new physics.

Whether the topic should be listed in this article depends on what this article is about. To me, it's not clear what this article should talk about: should it list all the subjects that physicists are working on ? The list could be long ! Should it be limited to the "top" issues ? Yes, but then we would need a source for this, instead of relying on the opinions of the wikipedians. I looked for lists of unsolved issues in physics on the internet, and there are several, but they do not agree on the top issues. So maybe we should make a separate article for each source. Otherwise, this article will be endlessly debated. Pcarbonn 14:35, 17 June 2006 (UTC)

Most likely the problem exists only since the guys who work on the problem just don't want to find the solution. The solution is supplied by Einstein's theory of 1915. It is in its math. I told them about it and how it predicts the 'anomaly' with a prediction that is off only by less than half of standard deviation from what they observe.

The solution is (c sqrt(4 pi G rho)) where c = 3x10^8, pi = 3.14, G = 6.7x10^(-11), and rho = 6.5x10^(-27) the density of space of the universe, all in "engineering" units. It is just the formula for relativistic dynamical friction and it's even the same for photons, observed for already over 70 years in form of Hubble's redshift.

So they don't even have a good excuse why they don't apply Einstein's physics. They just said "they don't believe it" without even looking into it. Unfortunately I have only a degree in engineering so I'm not an authority on GR. And I don't know why GR supplies such exact prediction. I just calculated it using Einstein's physics so I knew that it could be calculated and I wondered why the guys who were paid for doing it didn't.

Apparently the problem is that astrophysicists use only Newtonian physics "with corrections for relativistic effects". And the effect is purely relativistic but not a one for which Newtonian physics was ever corrected. Mathematicians ignored dynamical friction of photons because they considered it 'negligible' and so they didn't correct for it the equations the astrophysicists use in their calculations. So the problem might be never solved unless astrophysicists start learning Einstein's physics to be able to solve such simple problems directly as I did. So this one is not really a physical problem but a sociological one. Unfortunately nothing can be done since there is no communication between scientists and engineers who can't publish anything in "scientific journals" since what engineers discover "isn't interesting to physicists" even if true (as editors of Phys. Rev. Lett. told me).

Like for instance a fact that the universe isn't expanding. Or like when CMBR was discovered by Penzias and Willson around 1960's I knew already about the universe being 3K cool since the radio engineers discovered "background noise" many years earlier and atributed it to the "average temperature of the universe", apparently at that time a fact not known yet to physicists. Similarly as now they don't know why the space probes slow down despite that it is required by the standard physics they are supposed to know (if stupid engineers may know it). Jim 02:29, 11 November 2006 (UTC)

[edit] problem

on a long distance car trip a person travels 800 km north (straight line distance on a map) in 12 hr. (a)what was the average speed? (b) what was the average velocity?

This isnt a place for you to ask homework questions. Wikipedia does not provide that service. Philc _T^E_C^I 23:15, 17 July 2006 (UTC)

shame crap like this cant be deleted. h0riz0n 16:28, 19 August 2006 (UTC)

Hey, be bold, there are no rules, etc: if you really want to delete it, along with this comment too, go ahead. I would have, but I think it's funny. While this particular problem is almost certainly solved, I'm currently thinking of a very similar problem which is unsolved. Trouble is, if I write it here, some palooka will probably solve it. --Homunq 21:54, 14 November 2006 (UTC)

[edit] Quantum Teleportation

It seems to me that quantum teleportation is still very much a mystery. How can a particle instantly teleport from here to the center of the multiverse? h0riz0n 16:23, 19 August 2006 (UTC)

Good question. actually, though, quantum physics is based on the assumption that all standard physics laws are tossed out the window at the subatomic level, so while it doesn't make sense to us at our level of the physical realm, it does make sense according to the laws of quantum physics. 63.16.141.115 20:17, 16 September 2006 (UTC)

[edit] Phenomena or established occurrences

I don't see sufficient difference between these terms to have them both in the header. I think Phenomena can encompass both. - 64.228.218.247 16:05, 22 September 2006 (UTC)

[edit] Charge

Charge: What gives quarks charge, why do different particles have different denominations of it, and why do opposite charges attract?

I suppose this question means to ask "why do quarks have the hypercharge, SU(2), and/or color charges that they do". That's a great unanswered question. However, we know why opposite (electric) charges attract. Given the interactions that define the charge (you must have these for a charge to exist), you can calculate the potential between two charged objects and show explicitly that the force between oppositely charged objects is attractive. I therefore propose to remove the last clause in the sentence. HEL 00:22, 16 November 2006 (UTC)

There, I was bold and did it. HEL 00:24, 16 November 2006 (UTC)

[edit] Broken external link

This external link is broken (article can't be found), so I removed it from the main article. I'm not sure what it could refer to, since the dark matter problem is not actually solved... HEL 00:29, 16 November 2006 (UTC)

• Dark Matter - one problem solved

[edit] Accelerating universe

This is not an unsolved problem anymore. Over 20 years ago it has been found out that both, expansion and its acceleration are only apparent. It turned out that Einstein's gravitation can explain more than comologists thought since there is more limitations placed on curvatures of spacetime than cosmologists are willing to admit. So it is just argument between cosmologists and astrophysicists in which cosmologists still have upper hand because they control the sientific journals. The cosmologists don't allow valitity of conservation of energy while astrophysicists insist on it. According to Einstein's gravitation (in astrophysical version) the numbers for apparent expansion for curvature of space 1 / R = 1 / 4.1Gpc ^{− 1} are H₀ = 73km / s / Mpc and . Jim 09:40, 18 November 2006 (UTC)

[edit] Heavy bias in favor of particle physics

This article as it currently stands is too heavily biased in favor of particle physics. Gibimi 19:02, 26 November 2006 (UTC)

Disagree. In my mind, particle physics is physics (ok, cosmology too, but they're basically the same thing when you get right down to it). Everything else is applications of physics. So I think that things like turbulence only have a marginal place on this page. I understand, however, that not everyone shares this view... --Strait 19:15, 26 November 2006 (UTC)