Re: Dark Matter Update

[Brent Meeker]

Sounds right to me.

Brent

On 12/16/2021 3:37 PM, Tomas Pales wrote:
If dark matter interacts only weakly with itself and with ordinary 
matter does it mean that it is less susceptible to quantum decoherence?


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Re: Dark Matter Update

[Tomas Pales]

If dark matter interacts only weakly with itself and with ordinary matter 
does it mean that it is less susceptible to quantum decoherence?

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Dark Matter Update

[John Clark]

In the last few months there have been some developments in the hunt for
Dark Matter, unfortunately they tell us what Dark Matter isn't rather than
what it is. One of the most popular theories, the idea that Dark Matter is
made of sterile neutrinos, now appears to be most likely untrue according
to a recent experiment at the MicroBooNE detector at Fermilab. The idea may
not be completely dead but it is certainly badly wounded:

Search for Neutrino-Induced Neutral Current Δ Radiative Decay in MicroBooNE
and a First Test of the MiniBooNE Low Energy Excess Under a Single-Photon
Hypothesis 

Another idea is that Dark Matter doesn't really exist and we need to modify
our understanding of gravity, especially General Relativity. That idea has
been just about destroyed by the discovery of a very odd type of galaxy
called Ultra Diffuse Galaxies (UDG). Only about a dozen UDG's have been
discovered and are about as large as the Milky Way but have 1000 times
fewer stars and not much gas or dust, but that's not the strangest thing
about them. UDG's were found to contain very little Dark Matter. Because
they are so dim UDG are hard to observe, so some have suggested the
observed lack of Dark Matter was simply due to observational inaccuracies,
but on December 2 researchers reported on the most detailed observation of
a UDG so far and they were unable to find any Dark Matter in it. Zero. To
predict the motions of the stars in a UDG all you need is Kepler's laws of
planetary motion and there would be no need to invoke Dark Matter or modify
Newtonian gravity at all, much less Einsteinian gravity.

No need for dark matter: resolved kinematics of the ultra-diffuse galaxy
AGC 114905 

And Einstein's General Relativity doesn't seem to need a modification
because it just passed with flying colors its most stringent test ever.
Astronomers have been observing a double pulsar, 2  Neutron Stars orbiting
each other every 147 minutes at a speed of 620,000 MPH, one neutron star
rotates once every 2.8 seconds and the other rotates 44 times a second; on
December 13 they reported on the results of 16 years of observations and
they were compatible with the predictions made by General Relativity within
the margin of error, if there was any conflict it was less than one part in
7700.

Strong-Field Gravity Tests with the Double Pulsar


So we know more about what Dark Matter isn't but we still don't know what the
hell it is. And Dark Energy is even more mysterious.

By the way, the Webb Telescope is now scheduled to be launched no earlier
than Christmas Eve.

John K ClarkSee what's on my new list at  Extropolis

uud

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