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Author: Subject: Scientists find possible ‘fifth force of nature’?
Velzee
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[*] posted on 24-11-2019 at 00:57
Scientists find possible ‘fifth force of nature’?


Maybe it’s because I’m sleep deprived, but this is not making much sense to me. I would appreciate your opinions:

https://www.dailymail.co.uk/sciencetech/article-7717425/amp/...




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[*] posted on 24-11-2019 at 03:46


I think there has been a bit of news on this but I have not kept up with it.
For helpful videos, Dr Becky has a 25 minute YT clip on it and Anton of What the Math has a 13 minute video. Both are usually good at explaining these kinds of things. But I confess I have not watched either yet.
(Edit: watched both now. Interesting stuff. But probably only tangentially related to the article you cited. However, this fifth orce stuff has come up before.)

For me, I find this level of physics a bit frustrating because at its heart it is rather complex and the mathematics is certainly above my head. When people explain it I find it difficult to distinguish between
  • assumptions (either conscious or otherwise)
  • simplifications so that the uninitiated like me have a chance of understanding
  • accepted but unproven theories
  • observations and results calculated from data (which may or may not be based on aforementioned hidden assumptions or unproven theories).

    I have a few people that I learn well from but an awful lot is taken on trust. (Dr Lincoln of Fermilab is probaby my favourite.)

    [Edited on 24-11-2019 by j_sum1]
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    [*] posted on 24-11-2019 at 19:24


    And here it is... an explanation.
    https://www.youtube.com/watch?v=Q6GhM_2_P_g
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    annaandherdad
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    [*] posted on 25-11-2019 at 09:44


    Here is the article:
    https://arxiv.org/pdf/1910.10459.pdf
    The result is primarily experimental, with various theoretical implications. The Hungarian group has measured correlations in electron-positron pair production in the decay of the Be8 nucleus that suggest that the e+e- pair came from the decay of a new particle of mass about 17MeV.

    The first question is whether the experimental results are reliable and reproducible. The first observation was by the same group about 3 years ago, and now they have better data that seems to confirm it. No one has raised serious objections to how the result was obtained but it would help if there were confirmation from other groups, hopefully also involving other nuclei beside He and Be. It's likely that there will be a lot of activity in this area soon, to confirm or shoot down the observations.

    In the meantime, it has to be said that any discovery of a new particle in this mass range would be extremely significant for particle physics and possibly for cosmology. The fact that the particle decays to two fermions e+e- means that it itself is a boson; bosons are the particles that mediate forces, for example, the photon (with spin 1) mediates the electromagnetic force. Hence the talk about a "fifth force."

    The standard model currently accounts for almost all experimental data, but it has a number of apparently arbitrary parameters and no one believes it is fundamental. Thus there is great interest in any kind of physics that is "beyond the standard model." Among the small discrepancies between observation and the standard model theory are the "strong CP problem" and the anomalous magnetic moment of the muon, both of which are referred to in the article cited above.

    The strong CP problem refers to the fact that the upper limit on the electric dipole moment of the neutron is below what the standard model would predict. The problem can be fixed by postulating a new particle, the "axion", which however has never been observed. The hypothetical axion is also a candidate explanation for dark matter.

    Dark matter is not by itself an observation, it's an hypothesis that explains the extra mass that seems to be needed to explain the dynamics of galaxies.(For example, galaxies rotate too fast to be explained by the gravity of the observable mass, hence the guess that there is extra, "dark" mass). If dark matter really is the axion, then cosmology and particle physics both get an explanation of new physics.

    I would expect to see a lot of activity on the question of this new particle, and if the experimental data holds up and there really is a new particle, it will be extremely significant.




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    pantone159
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    [*] posted on 25-11-2019 at 17:15


    Thanks for posting the arxiv link. It sounds like the authors found similar results with a new atom, He-4, that they did with a previous one Be-8. It sounds interesting. I do not know enough particle physics to figure out how much sense this really made, but it did not come off as nonsense. The authors also mentioned some future experiments from other groups that will try and look at this.

    Personally, I hope it holds up! If there is some kind of new particle, maybe we can finally get a hint of dark matter. But experiment will tell.
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    [*] posted on 26-11-2019 at 04:32


    I recommend quantumdiaries' blog on the Be-8 result, which I found very clarifying:

    https://www.quantumdiaries.org/2016/08/25/the-delirium-over-...

    The same Hungarian group now reports a similar observation with a different nucleus (He-4)

    Very interesting. Looking forward to hearing if it can be independently replicated.

    [Edited on 26-11-2019 by phlogiston]




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