What experiments at quantum or cosmic level might provide the strongest supporting evidence for or, conversely, potential for falsifying, the existence of dark matter or dark energy?
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$\begingroup$ To falsify dark matter may be a little hard at the moment. If you want to know about dark matter searches then you can start here en.wikipedia.org/wiki/… and drill down. $\endgroup$– CuriousOneCommented Jun 1, 2015 at 2:24
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1$\begingroup$ LHC will be at full capacity in a few weeks. If there are supersymmetric particles under 13 tev , it will find them surely. Dark energy is another story. $\endgroup$– user46925Commented Jun 1, 2015 at 3:25
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3$\begingroup$ @igael: the effective center of mass energy of the constituents is not the same as the center of mass energy of the protons. It would be nice if LHC was a real 14TeV center of mass machine, but it's not. The SUSY searches I have seen seem to be focused on the <1TeV energy range and the missing energy sensitivity seems to take a dive at 1TeV, too. Can you point me to a paper which promises 13TeV superpartner detection? $\endgroup$– CuriousOneCommented Jun 1, 2015 at 3:37
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1$\begingroup$ @igael: I worked on some LHC hardware once and even I had some misconceptions about it in the beginning. The 1TeV limit is "somewhat" conservative, it seems. Matt Strassler wrote a nice summary here discussing the case of the lightest sparticles up to 1.8TeV: profmattstrassler.com/articles-and-posts/… $\endgroup$– CuriousOneCommented Jun 1, 2015 at 5:35
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1$\begingroup$ XENON 1 Tonne, new limits expected in the new year - should find DM or set world-leading limits on cross-sections with nucleons. $\endgroup$– innisfreeCommented Dec 17, 2015 at 4:24
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2 Answers
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The ALPHA experiment at CERN is attempting to ascertain the gravitational properties of anti-hydrogen. Most physicists expect that anti-matter will fall (be attracted) in a gravitational potential generated by matter. If it turns out that anti-matter is repelled by ordinary matter, then this could explain dark energy and also solve the baryon asymmetry problem.
In this scenario the lack of evidence for anti-matter could be an artifact of our limited ability to detect it's signature outside of our local super cluster of galaxies (which would be devoid of anti-matter). Other super clusters could be made entirely of anti-matter (and repell super clusters made of ordinary matter) and the universe could be matter/anti-matter symmetric.
For this to be consistent with the large scale distribution of dark matter (connected filaments with galatic super clusters arrayed like beads on a string), it would be necessary for the dark matter partcle (whatever it is) to be it's own anti-particle and for dark matter to be attractive to both matter and anti-matter (of the ordinary type) under gravity.
answered Dec 17, 2015 at 4:00
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$\begingroup$ Your answer suggests that antimatter=dark matter. This is definitely not the case. We would see light from anti-atoms just like we do from regular atoms, and in fact can't distinguish one from the other. Dark matter is something else that we can't see in radio/light/xrays. Dark matter is an "invisible" hypothesized stuff that was first added to make Newton's Law of gravity work to predict the flattening of the tangential rotational velocity seen in spiral galaxies as you go out in radius. $\endgroup$ Commented Dec 17, 2015 at 6:11
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1$\begingroup$ @ Gary Godfrey No, not at all. I'm saying nothing about what dark matter is except that it is it's own anti-particle (like the photon, for example) and also that it would attract both ordinary matter and anti-matter. $\endgroup$ Commented Dec 17, 2015 at 14:11
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$\begingroup$ Why do most physicists suspect that antimatter would be gravitationally attracted to matter? I'm surprised that property wouldn't have been verified by now ... $\endgroup$– Time4TeaCommented Oct 5, 2019 at 12:34
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$\begingroup$ @Time4Tea If matter and anti-matter repelled rather than attracting it would violate the equivalence principle of general relativity. Experiments with antimatter are very difficult. $\endgroup$ Commented Oct 5, 2019 at 18:46
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One approach could be made ie. by concluding the Cavendish experiment on ISS.
As it would show if there is difference in Gravitational constant, and might thus open the door to new ideas about the mechanic of Gravity. If the gravitational constant is not a constant, then there is no need for dark matter and dark energy. I have a question about this issue; Gravitational constant, $G$, What if it is not Constant? and I have even tried to improve the idea further with this question; https://physics.stackexchange.com/questions/220050/le-sages-theory-of-gravitation-is-drag-the-only-reason-why-this-theory-fails
There is also MoND theories, "Modified Newtonian dynamics" which would falsify the dark Matter theories. It has shown some success explaining the dynamics of galaxies. One of its aspects is the Implications of Unruh-inertia to theories of gravity There is some resent papers published about these issues; ie. Testing Quantised inertia on Galactic scales
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$\begingroup$ I do not think MoND theories are meant to falsify DM/DE theories. As I understand it, DM/DE is just a place-holder (much like the 'x' in x-Rays). With our experiments we can figure some properties of DM/DE but that's about it. MoND/modified theories of gravity are some of the possible wayz in which one could explain the origin of DM/DE. There are ofcourse other possibilities out there (eg- Axions, WIMPs etc) $\endgroup$ Commented May 29, 2018 at 15:34