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Dark matter, is it real?

Started by Bluenose, November 18, 2021, 11:41:43 PM

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Bluenose

Found this video, might be of interest to some here. It certainly poses some interesting questions.  I haven't found the paper described in it, but then I have not really looked...   ::)

https://youtu.be/0sTBZ2G4vow
+++ Divide by cucumber error: please reinstall universe and reboot.  +++

GNU Terry Pratchett


Recusant

Fine stuff, thank you Bluenose. The menagerie of MOND theories is something to behold. There's no denying the entertainment value of watching physicists and cosmologists do mental gymnastics trying to deal with the anomalous galactic rotation speeds. Good for them to have something to chew on.  :thumbsup2:

I noticed that the graphics don't add much to the video, and it works pretty well as a podcast. The host is good at what he does, but I'd say he's a natural for podcasts.  ;)

As for the paper, I don't mind admitting the equations are well beyond me, as is a fair part of the text when it begins blending in with the equations. Those with a superior education may make better headway. It seems to have been published in Physical Review Letters, but I found it on arXiv.

"New Relativistic Theory for Modified Newtonian Dynamics" | arXiv

QuoteWe propose a relativistic gravitational theory leading to modified Newtonian dynamics, a paradigm that explains the observed universal galactic acceleration scale and related phenomenology. We discuss phenomenological requirements leading to its construction and demonstrate its agreement with the observed cosmic microwave background and matter power spectra on linear cosmological scales. We show that its action expanded to second order is free of ghost instabilities and discuss its possible embedding in a more fundamental theory.
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Bluenose

Quote from: Recusant on November 19, 2021, 03:51:00 AM
Fine stuff, thank you Bluenose. The menagerie of MOND theories is something to behold. There's no denying the entertainment value of watching physicists and cosmologists do mental gymnastics trying to deal with the anomalous galactic rotation speeds. Good for them to have something to chew on.  :thumbsup2:

Tank may recall me sitting in his front room back in 2016 saying that I think we are close to a revolution in physics similar in many ways to that caused by Einstein and Co.  Things like this possible resolution to some pretty big cosmological questions as well as some new thinking about the standard model of sub atomic particals suggest, to me at least, that we are about due to a new revolution.  I suspect that like relativity v Newtonian physics where Newtonian physics has been shown to be basically a special case of relativiy, whatever the new physics ends uo being our current understandings will probably become just special cases that work for most examples but beyond certain limits the new stuff will be required.  I hope I live to see some of this.

Quote
"New Relativistic Theory for Modified Newtonian Dynamics" | arXiv

QuoteWe propose a relativistic gravitational theory leading to modified Newtonian dynamics, a paradigm that explains the observed universal galactic acceleration scale and related phenomenology. We discuss phenomenological requirements leading to its construction and demonstrate its agreement with the observed cosmic microwave background and matter power spectra on linear cosmological scales. We show that its action expanded to second order is free of ghost instabilities and discuss its possible embedding in a more fundamental theory.


Yeah, that's what I thought...   ::)
+++ Divide by cucumber error: please reinstall universe and reboot.  +++

GNU Terry Pratchett


Dark Lightning

I graduated with a B Sc in physics in '83 and started in on a master's in '84. First up was General Relativity, but I made it about 3 weeks and decided I wasn't going to be the one to update Einstein's work.  ::)  I find the general discussion interesting, but I don't want to bash that math into my head at this late age.

hermes2015

Quote from: Dark Lightning on November 19, 2021, 02:53:20 PM
I graduated with a B Sc in physics in '83 and started in on a master's in '84. First up was General Relativity, but I made it about 3 weeks and decided I wasn't going to be the one to update Einstein's work.  ::)  I find the general discussion interesting, but I don't want to bash that math into my head at this late age.

I agree with you. I have a BSc in physics and also in chemistry, but at 75 I would rather solve painting and sculpture problems, and try to improve my knowledge of classical music.
"Who is to say that pleasure is useless?"
― Charles Eames

Dark Lightning

Quote from: hermes2015 on November 20, 2021, 03:15:56 AM
Quote from: Dark Lightning on November 19, 2021, 02:53:20 PM
I graduated with a B Sc in physics in '83 and started in on a master's in '84. First up was General Relativity, but I made it about 3 weeks and decided I wasn't going to be the one to update Einstein's work.  ::)  I find the general discussion interesting, but I don't want to bash that math into my head at this late age.

I agree with you. I have a BSc in physics and also in chemistry, but at 75 I would rather solve painting and sculpture problems, and try to improve my knowledge of classical music.

:thumbsup: I'm working on carving skills, with a side order of copper smithing. But I haven't hammered any copper in years. I have some sheets that are calling to me. I would rather just appreciate music, though (listening).

billy rubin

Quote from: hermes2015 on November 20, 2021, 03:15:56 AM
Quote from: Dark Lightning on November 19, 2021, 02:53:20 PM
I graduated with a B Sc in physics in '83 and started in on a master's in '84. First up was General Relativity, but I made it about 3 weeks and decided I wasn't going to be the one to update Einstein's work.  ::)  I find the general discussion interesting, but I don't want to bash that math into my head at this late age.

I agree with you. I have a BSc in physics and also in chemistry, but at 75 I would rather solve painting and sculpture problems, and try to improve my knowledge of classical music.

attaboy.

the peoplr who never alter their interests go pretty deep, but nevrr very far.


more people have been to berlin than i have

Recusant

This hypothesis is nice, and the article says that the large collider that CERN has planned for completion in 2035 may help determine whether there's anything to it.  :hourglass:

"Dark matter could be a cosmic relic from extra dimensions" | Live Science

QuoteDark matter, the elusive substance that accounts for the majority of the mass in the universe, may be made up of massive particles called gravitons that first popped into existence in the first moment after the Big Bang. And these hypothetical particles might be cosmic refugees from extra dimensions, a new theory suggests.

The researchers' calculations hint that these particles could have been created in just the right quantities to explain dark matter, which can only be "seen" through its gravitational pull on ordinary matter. "Massive gravitons are produced by collisions of ordinary particles in the early universe. This process was believed to be too rare for the massive gravitons to be dark matter candidates," study co-author Giacomo Cacciapaglia, a physicist at the University of Lyon in France, told Live Science.

[. . .]

In the team's theory, when gravity propagates through extra dimensions, it materializes in our universe as massive gravitons.

But these particles would interact only weakly with ordinary matter, and only via the force of gravity. This description is eerily similar to what we know about dark matter, which does not interact with light yet has a gravitational influence felt everywhere in the universe. This gravitational influence, for instance, is what prevents galaxies from flying apart.

"The main advantage of massive gravitons as dark matter particles is that they only interact gravitationally, hence they can escape attempts to detect their presence," Cacciapaglia said.

[Continues . . .]

The paper is open access:

"Massive Gravitons as Feebly Interacting Dark Matter Candidates" | Physical Review Letters

"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Bluenose

#8
This article about the measurement of the mass of the W boson by CERN contains this wonderfully understated expression about the fact that the standard model may well be broken "This measurement is in significant tension with the standard model expectation."

The re-organisation of particle physics may well be underway!
+++ Divide by cucumber error: please reinstall universe and reboot.  +++

GNU Terry Pratchett


Ecurb Noselrub

I'll just have to wait for the final conclusion. My background in law does not equip me for playing this game.  I'll be a spectator and utter the occasional "wow!".