4 ms·

As long as there is no theory on dark matter it is not an explanation for anything. It's more a placeholder for a mechanism we don't understand. The best hypoth

by maze-le 10y ago

As long as there is no theory on dark matter it is not an explanation for anything. It's more a placeholder for a mechanism we don't understand. The best hypothesis so far is, that there is matter that doesn't interact electromagnetically. But this explanation shouldn't be confused with a theory that actually explains what is going on.

acqq 10y ago
No, it's not a placeholder. There are the exact formulas that match what's observed. https://medium.com/starts-with-a-bang/7-independent-pieces-of-evidence-for-dark-matter-3692126a2283 https://medium.com/starts-with-a-bang/7-independent-pieces-o... No other approaches (MOND included) are near, still. MOND can at the moment match just one of the 7 different kinds of observations listed above. That's why the physicists aren't impressed. And all the observations are not going away, even if MOND manages once to produce enough formulas to cover them or to be a better basis to explain the observation, see my other comment. Where did you get this "no theory" claim?
- maze-le 10y ago
  "no theory" because we don't know what this matter really is. Up to now, explanations on the nature of the matter have problems in one way or another. High Energy Neutrinos are too light and not abundat enough. Axions were once a promising particle, that could explain dark matter phenomenology, but if axions were produced in stars, variable stars would oscillate in other frequencies. Supersymmetric partners are not ruled out but become increasingly difficult to explain, because the lightest susy-particle has not been found in the LHC experiments. Yes, "no theory" is maybe not the best choice of words, lets call it "no verified theory". By the way, I don't think MONDs are a good explanation either.
  - gpderetta 10y ago
    Massive sterile neutrinos, which are are part of a theory of explaining the very low neutrino masses, are also dark matter candidates.
  - acqq 10y ago
    It is already "verified," (as in, observations are there) it's that there are extensions of particle physics like WIMP for which these researchers would have liked to be able to fit them to the observations of the dark matter, and the conclusion is: http://www.forbes.com/sites/startswithabang/2016/07/21/dark-matter-may-be-completely-invisible-concludes-worlds-most-sensitive-search http://www.forbes.com/sites/startswithabang/2016/07/21/dark-... "The null detection is incredible, with a fantastic slew of implications: - Dark matter is most likely not made up, 100%, of the most commonly thought-of WIMP candidates. - It is highly unlikely that whatever dark matter is, in light of the LUX results, will be produced at the LHC. - And it is quite likely that dark matter lies outside of the standard mass range, either much lower (as with axions or sterile neutrinos) or much higher (as with WIMPzillas)." (I'm not quoting it for you, but for possible others to get the idea what the topic is). So it's that these popular supersymmetry models turned out that they don't fit to the experiments. It's just problematic for those that expected too much of the supersymmetry approach. It's good that some researchers try with MOND too -- sometimes there are some new results exactly there were they are less expected. But they have quite a lot to do to match what's easier to do otherwise.
    - deleted 10y ago
      [deleted]

by maze-le 10y ago

acqq 10y ago

No, it's not a placeholder. There are the exact formulas that match what's observed. https://medium.com/starts-with-a-bang/7-independent-pieces-of-evidence-for-dark-matter-3692126a2283 https://medium.com/starts-with-a-bang/7-independent-pieces-o... No other approaches (MOND included) are near, still. MOND can at the moment match just one of the 7 different kinds of observations listed above. That's why the physicists aren't impressed. And all the observations are not going away, even if MOND manages once to produce enough formulas to cover them or to be a better basis to explain the observation, see my other comment. Where did you get this "no theory" claim?

maze-le 10y ago
"no theory" because we don't know what this matter really is. Up to now, explanations on the nature of the matter have problems in one way or another. High Energy Neutrinos are too light and not abundat enough. Axions were once a promising particle, that could explain dark matter phenomenology, but if axions were produced in stars, variable stars would oscillate in other frequencies. Supersymmetric partners are not ruled out but become increasingly difficult to explain, because the lightest susy-particle has not been found in the LHC experiments. Yes, "no theory" is maybe not the best choice of words, lets call it "no verified theory". By the way, I don't think MONDs are a good explanation either.
- gpderetta 10y ago
  Massive sterile neutrinos, which are are part of a theory of explaining the very low neutrino masses, are also dark matter candidates.
- acqq 10y ago
  It is already "verified," (as in, observations are there) it's that there are extensions of particle physics like WIMP for which these researchers would have liked to be able to fit them to the observations of the dark matter, and the conclusion is: http://www.forbes.com/sites/startswithabang/2016/07/21/dark-matter-may-be-completely-invisible-concludes-worlds-most-sensitive-search http://www.forbes.com/sites/startswithabang/2016/07/21/dark-... "The null detection is incredible, with a fantastic slew of implications: - Dark matter is most likely not made up, 100%, of the most commonly thought-of WIMP candidates. - It is highly unlikely that whatever dark matter is, in light of the LUX results, will be produced at the LHC. - And it is quite likely that dark matter lies outside of the standard mass range, either much lower (as with axions or sterile neutrinos) or much higher (as with WIMPzillas)." (I'm not quoting it for you, but for possible others to get the idea what the topic is). So it's that these popular supersymmetry models turned out that they don't fit to the experiments. It's just problematic for those that expected too much of the supersymmetry approach. It's good that some researchers try with MOND too -- sometimes there are some new results exactly there were they are less expected. But they have quite a lot to do to match what's easier to do otherwise.
  - deleted 10y ago
    [deleted]