Talk:Mirror matter/Archive 1

The article was so bad, it should be completely removed. So its done.

Egbert, please don't blank pages. If you think an article is inappropriate, it should be deleted via the proper mechanism, Wikipedia:Votes for deletion (let me warn you that this is unlikely to succeed, but you can try). Otherwise, please find other venues to fix the article. Thanks. Gadykozma 02:21, 20 Oct 2004 (UTC)

Statement from Nima Arkani-Hamed

I've asked Nima Arkani-Hamed, who is a leader of particle physics today. He answered that these theories are pretty crappy, but also explained me what is exactly doubled. The answer is simple: everything (except for gravity) is doubled. Imagine that there is another brane that looks just like ours, and has a new SU(3) for QCD, and all new copies of all particles of the Standard Model. Then it will interact with us gravitationally only, like other hidden sector theories. If you "fold" a brane, it's an easy way to visualize that the parity can be reverted on the other brane (although there is nothing "better" about the other brane being a mirror image of ours, as opposed to an exact copy). Nima says that these theories have however bad phenomenology - the matter is not "wimpy", i.e. it is not weakly interacting, and it is very efficient in cooling itself down. --Lumidek 15:49, 19 Oct 2004 (UTC)

For the record, there aren't strong observational limits on the cross sections between dark matter particles. In fact, the DM-DM and DM-baryon cross sections can be close to about 1 barn. Such huge cross sections have been postulated by Paul Steinhardt who, b.t.w. is no less a leader in astroparticle physics than Nima Arkani-Hamed. See also Simp.Count Iblis 21:44, 2 January 2006 (UTC)

This article is nonsense

Let me just say that from a particle physics perspective, this article is a mere nonsense, much like articles on astro-ph section of arxiv.org posted by R. Foot et al. We know exactly what C,P,CP violation mean, and they do not imply anything such as "mirror matter", except for antimatter. One can *add* a whole family of new particles and fields, but they will not be dark as long as they will interact electromagnetically. Electromagnetism does not distinguish "left" and "right". Any particle interacting electromagnetically can be produced at accelerators, and we simply know all such charged particles lighter than 100 GeV or so. If you care, I am an assistant professor of theoretical physics at Harvard. --Lumidek 13:07, 19 Oct 2004 (UTC)

Lumidek, this time I'll change the article — next time just do it yourself. Gadykozma 13:40, 19 Oct 2004 (UTC)

Dear Gadykozma, your edit looks very nice. I did not want to change the article directly before I made a more complete research of the topic. Look at [1] and you will see the articles of Robert Foot from Australia. Robert Foot is probably a guy who often comes to improve this page ;-) - and who also anonymously destroys the pages on supersymmetry, Edward Witten, string theory, and superstring theory from the host 211.28.*.*. ;-) If you look at various articles citing these papers about mirror dark matter, you will see that virtually all of them have either R.Foot or P.Ciarcelluti between their authors, so your term "fringe theory" is justified. Otherwise, dark matter can be made of many different things, and this specific proposal does not seem to be well-justified by particle physics. There is nothing wrong with the P violation, but one can construct GUT-like models whose gauge groups contain the right-handed analogues of SU(2) electroweak. That's all great, but even if we assume that these models are realistic, it is guaranteed experimentally that the exact symmetry between the left and the right groups must be broken, and it is probably broken at a very high scale. It's also very confusing to talk about "mirror baryons". One must decide whether we want to split the SU(3) group of quantum chromodynamics to two different groups. In both cases we get not-quite-the-desired models. I will ask some astroparticle experts around and tell you more.--Lumidek 14:57, 19 Oct 2004 (UTC)

Wouldn't it be better if a physicist were to change the page, even before researching the topic, than a mathematician with no formal background in physics, based on the same physicist remarks? If you can write a good rebuttle of these theories that would be understandable for, say, a graduate student, and add it to this page, that could be very nice. Gadykozma 15:28, 19 Oct 2004 (UTC)

Older comments

I removed the following text from the article:

In recent years experimental evidence for mirror matter has emerged from a variety of sources including direct dark matter detection experiments, anomalous meteorite events, Tunguska event etc.

This sentence seems unwarranted for several reasons.

• "Direct dark matter detection experiments" have, to my knowledge, produced little more than upper bounds on the various candidates. (For example, after the 1987 Magellanic Cloud supernova, we learned that the neutrino mass is probably too small to make it a plausible primary dark matter constituent.) If experiments had produced definitive data, then the people in my lab would be out of work.
• The Tunguska "event" can be explained by a bolide impact. Whether it was a comet or a small asteroid remains an open question, but we hardly need to postulate an entirely unknown form of matter to explain what a lump of ice could already account for.

Anville 16:52, 12 Oct 2004 (UTC)

Removed material

I have removed a large chunk of information about the DAMA experience. I thought it was too detailed for this article and would be better off in the dark matter page. I kept the few relevant links. Gadykozma 01:18, 24 Oct 2004 (UTC)

On which peer reviewed articles is this comment based on?

The vast majority of the physicist community rejects this theory. The main arguments against this theory are that mirror matter would need to interact electromagnetically far beyond the observed physical properties of the (still hypothetical) dark matter; and that if mirror matter existed it would have been observed in particle accelerators.

Utter nonsense. On which peer reviewed articles is this comment based on? I agree that mirror matter theory is not very popular, but that doesn't mean that it is wrong. On the contrary, articles on mirror matter have appeared in peer reviewed journals. If there were any truth in the above quote then that would not have happened.

I will edit this page again. Anyone is allowed to change it, but I urge you to do so on the basis of peer reviewed articles (Phys. Rev. D., Physics letters B, Journal of high energy physics, etc.), and not on the basis of what ill informed laymen are posting on various messageboards.

If you say that physicist John Doe says that Mirror Matter theory is nonsense, then just wait until he publishes a paper proving his assertions. Or why not submit an article to Phys. Rev. D yourself?

Suggested title: Mirror Matter Excluded by Accelerator Experiments

Suggested abstract: We show that experiments from particle accelerators imply that the photon-mirror photon kinetic mixing parameter has to be less than 10^(-10).

Removed last paragraph

I removed the last paragraph, because it was wrong. It is not true that mirror matter would necessarily have to interact with ordinary matter via electromagnetic interactions. Anyone making this assertion has to back that up by giving references to peer reviewed journals. Or if he/she is the first to make this observation, then this result has to be published first.

R. Foot has done some work on mirror matter interactiong with ordinary matter via photon-morror photon kinetic mixing interaction. This mixing has to be very small, less than 10^(-7), and is consistent with all experiments performed so far.

There is simply no way that someone could publish papers in leading peer reviewed journals on theories that are already excluded by experiments.

You may edit this page as you like, but the page must reflect the fact that this is a fringe theory. Any edits which try to hide or obfuscate this fact will not satisfy Wikipedia neutrality policy which is "absolute and non-negotiable". I will not go look for articles debunking mirror matter. Articles explicitly debunking fringe theories are very hard to find — you need a professional skeptic for that. As you say yourself — this theory is not very popular — the article must reflect this. Gadykozma 13:51, 24 Oct 2004 (UTC)

Your comments are complete nonsense. I will edit it again.

I will not go look for articles debunking mirror matter. Articles explicitly debunking fringe theories are very hard to find — you need a professional skeptic for that. As you say yourself — this theory is not very popular — the article must reflect this

As it is written now, it suggests that the theory is fundamentally wrong. This is false. I will include a list of all scientists who have published on mirror matter in the last few years. It is a short list, reflecting that it is not popular.

There are no articles debunking mirror matter. If there were Foot's articles wouldn't have been considered by editors in the first place. Go to the websites of phys. letters B, etc. and read the criterea any article has to meet before it can be consifered for publication.

I removed the suggestion that according to scientist mirror matter theory is nonsense. I did include that mirror matter is not a popular dark matter candidate.

The comments about mirror matter being in conflict with accelerator experiments are wrong, and I removed that.

Fringe theory?

Mirror Matter theory may be a fringe theory, but it is not shown to be in conflict with experiment. If that were the case then no articles on this theory would be accepted for publication in leading journals such as Phys. Rev. D, Phys. Lett. B, etc.

Editorial policy at Phys. Rev. D

Please do not copy large blocks of text from outside sources into Wikipedia. This is a copyright violation. Everything you post on Wikipedia must be yours to publish under the terms of the GFDL. See Wikipedia:Copyrights. Gadykozma 15:26, 24 Oct 2004 (UTC)

Suggestions for improvement

Models in which mirror symmetry is broken should also be mentioned. In this case the mirror particles are heavier than ordinary particles. I suggest people who want to do that to read articles by Mohapatra et al. and then to write a non-technical summary. Useful articles:

Mirror Matter MACHOs

Mirror Dark Matter and Core Density of Galaxies

Mirror Dark Matter