Dark Matter - ???

Echus_Chasma · 2002-12-29 16:18:24

Dark Matter, does any body have a clue to what it might be?

http://www.space.com/scienceastronomy/a … ...-1.html

Phobos · 2002-12-31 21:05:34

A lot of scientists think dark matter is just an exotic form of matter that only interacts with normal matter in a minimal number of ways like exerting a gravitational influence. I remember reading somewhere that dark matter might interact with nuetrinos(?) somehow and that that relationship might shed light on dark matter in the future. I don't remember if it was nuetrinos exactly but I think that was it.

oker56 · 2003-01-01 09:40:03

I recall physicists being excited about supersymmetry particles; yep, all the particles plus the antimatter versions now have other complementary particles! They have great theoretical reason's for being interested in supersymmetry; and with dark matter to be explained, they may have great observational evidence for supersymmetry. They still need to work on calculations and observational tests to confirm the connections.

oker56 · 2003-01-01 13:10:37

supersymmetry has to do with being able to renoralize theories that combine general relativity with quantum mechanics. Supersymmetry seems to be the only way to do so(string theory uses supersymmetry).

oker56 · 2003-01-01 13:16:32

Renormalizability has to do with getting a finite answer from previous infinities in the equations that combined special relativity with quantum mechanics. At first theorists and experimentalists thought renormalizability was just a calculation trick, but then they realized that quantum particles have less or more mass depending on how close you look at them(they seem to be pretty fractal objects); this led to the unification theories of the weak and quantum electrodynamics theories, and then later to grand unification theories(the combining of the strong nuclear, weak nuclear, and photon theories). As the temperature goes up, the strong nuclear force weakens, and the electromagnetic and weak nuclear forces get stronger.

I'm not to sure how much more details you want; i'm just saying ever more as I remember more; i really havn't thought about these things for awhile; i spend my time thinking about the nature of mathematics and the mind more these day's.

Echus_Chasma · 2003-01-01 14:11:54

Renormalizability has to do with getting a finite answer from previous infinities in the equations that combined special relativity with quantum mechanics. At first theorists and experimentalists thought renormalizability was just a calculation trick, but then they realized that quantum particles have less or more mass depending on how close you look at them(they seem to be pretty fractal objects); this led to the unification theories of the weak and quantum electrodynamics theories, and then later to grand unification theories(the combining of the strong nuclear, weak nuclear, and photon theories). As the temperature goes up, the strong nuclear force weakens, and the electromagnetic and weak nuclear forces get stronger.
I'm not to sure how much more details you want; i'm just saying ever more as I remember more; i really havn't thought about these things for awhile; i spend my time thinking about the nature of mathematics and the mind more these day's.

I think thats enough details for me.

I had to read it a few times to understand.

thank you.

Phobos · 2003-01-01 15:07:26

supersymmetry has to do with being able to renoralize theories that combine general relativity with quantum mechanics. Supersymmetry seems to be the only way to do so(string theory uses supersymmetry).

I'm still waiting for somebody to find a giant string floating around in space. Hey, it's theoretically possible if the string is made energetic enough and I think I'll put my new scope the challenge. I hope physicists make a lot of technological breakthroughs so they can test a lot of this stuff experimentally. Imagine the technology we might be able to create if we could unlock and test more of the aspects of string theory, etc. We might gain insight into how to tamper with space-time in ways we couldn't even think of before hand.

To get back to dark matter, there's a Boston Globe article http://www.boston.com/dailyglobe2/365/s … shtml]here about some evidence the Chandra x-ray scope found concerning darkmatter.

oker56 · 2003-01-01 15:48:38

seems the only way to test string theory is to study observational cosmology! and maybe some black holes . . .

oker56 · 2003-01-05 20:44:06

here's some exciting new astronomical observatory news in the line of trying to figure out dark matter.

http://icecube.wisc.edu/science/overview.shtml

Mark S · 2003-01-13 23:09:58

My physics professor from last semester believes that dark matter isn't exotic at all, it's just brown dwarfs and other failed stars. It may be worth noting that this professor is working on a theory of quantum gravitation; he claims to have amended Einstein's Unified Field Theory and thus has a working model for a four-dimensional universe.

SpaceNut · 2005-02-23 13:39:55

Welsh astronomers 'discover dark galaxy'

WELSH astronomers have discovered an object which appears to be an invisible galaxy made up almost entirely of dark matter.
The galaxy, the first of its kind to be detected, has been named VIRGOHI21.
It could only be found using radio telescopes because there are no stars to give light, the international team behind the discovery said.
The astronomers first took observations of the dark object in 2000 but it has taken almost five years to rule out all other possible explanations.

Astronomers find star-less galaxy

Astronomers claim first 'dark galaxy' find

First Invisible Galaxy Discovered in Cosmology Breakthrough

SpaceNut · 2005-03-04 09:45:30

Russia, Europe scientists to explore Dark Matter of universe using a newly designed a spectrometer.

Autonomous tests of the flight model of the PAMELA spectrometer have successfully gone at a special laboratory of the Rome University; they will be installed in the first satellite of a Resurs-DK series made at the Samara rocket centre TSKB-Progress
fluxes of galaxic space radiation will be studied, in the first place positrons and antiprotons containing information about the nature of Dark Matter
scientific tasks of the experiment are related to solving such fundamental problems as the nature of Dark Matter, generation and spread of galaxic space rays, processes on the sun and solar space rays, high-energy particles in the magnetosphere of the earth

SpaceNut · 2005-03-10 09:16:32

Evidence of dark matter missed 30 years ago

THE discovery in the 1990s that there could be some kind of mysterious dark energy that is accelerating the expansion of the universe came from studies of supernovae billions of light years away. Now, it turns out that the evidence for dark energy was there in our cosmic backyard all along, and that astronomers could have discovered it nearly 30 years ago.
It was reasoned by Allan Sandage of the Carnegie Observatories in Pasadena, California, that in the nearby universe - where the expansion is at its slowest - the gravitational attraction between groups and clusters of galaxies should produce significant deviations in their velocities from the otherwise largely smooth speed of expansion.

They figured that even if someone had written a paper in regards to the data that it would have still taken decades before computing power would have been enough to solve for it.

srmeaney · 2005-03-19 09:23:40

The type Ia supernova magnitude vs redshift curve data corresponds with the leading edge curve of:

dt=k^(magnitude-1)+{k^(magnitude)}

basicly it describes a repeating pulse of energy at various magnitudes proping up the acceleration curve.
{repeating cyclic event}.

SpaceNut · 2005-08-30 06:25:44

With Dark Matter there usually is the discusion of Dark energy.
Finding a Way to Test for Dark Energy

The SuperNova/Acceleration Probe, SNAP, is a satellite designed to study dark energy through the discovery and precision measurement of thousands of distant supernovae.

Dark energy is an exotic repulsive force that could make up as much as three-quarters of the cosmos. Possibilities include a cosmological constant or dynamical quintessence, both of which can be represented by scalar fields, like a field of springs covering every point in space.

SpaceNut · 2005-11-23 06:57:55

It would seem that measuring the light from supernova's has been used to come up with what would be the constant for dark matter.

Supernovae Back Einstein's "Blunder"

By measuring the distance to 71 distant supernovae, the scientists were able to ascertain with a high degree of confidence that dark energy exerts the same effect on supernovae light no matter what their distance. The researchers then plugged this finding into a so-called equation of state, which measures the relationship between pressure and density, and found that dark energy must be less than -.85, awfully close to Einstein's cosmological constant at -1.

Palomar · 2005-11-26 07:47:50

*Dark matter...dark energy...

I'll leave it to the scientists to figure out. There's so much speculation, various (sometimes seemingly contradictory) theories; it's one of the very few astronomy subjects which I feel reticent about.

--Cindy

noosfractal · 2007-08-17 01:19:03

Dark Matter Mystery Deepens in Cosmic "Train Wreck"

http://chandra.harvard.edu/press/07_rel … 81607.html

Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior.
...
A popular [but apparently wrong] theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster. However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies.

"It blew us away that it looks like the galaxies are removed from the densest core of dark matter," said Dr. Hendrik Hoekstra, also of University of Victoria. "This would be the first time we've seen such a thing and could be a huge test of our knowledge of how dark matter behaves."

In addition to the dark matter core, a corresponding "light region" containing a group of galaxies with little or no dark matter was also detected. The dark matter appears to have separated from the galaxies.

"The observation of this group of galaxies that is almost devoid of dark matter flies in the face of our current understanding of the cosmos," said Dr. Arif Babul, University of Victoria. "Our standard model is that a bound group of galaxies like this should have a lot of dark matter. What does it mean that this one doesn't?"
...

[ back to the drawing board ]

JoshNH4H · 2007-11-08 15:24:12

I think that dark matter is neutrinos
is this possible?
I'm not a physicist.

nickname · 2007-11-08 19:13:13

This is my idea of the bulk of dark matter.

If with go with just the seen stars in the galaxy we see about 1 giant blue star for every 10 yellow average stars.
For every 1 average yellow sun we see about 10 small red stars.
If we go one step further and account for 10 times as many non burning stars smaller than red suns.(very big Jupiters)
And 10 times that of Jupiter sized failed stars.
And 10 times that of Saturn sized failed stars.
We can then start accounting for quite a bit off the mass.

Going further on that idea with black holes.
If we count up the gamma ray bursts that happen each day and divide it with number of galaxies in the universe times the years the universe has existed times 365 days.
Then we get a number of unseen black holes in each galaxy.

Adding up the masses of stars to small to burn and accompanying planet masses with them and unseen black holes we get close to the dark matter mass numbers.

Dark energy.

In my opinion just a property of our 1 universe in a multi verse.

Dark energy is simply a pull of gravity from outside our universe from all other universes, and a property of time/space of our universe itself.
The expansion is the dark energy, the matter in our universe acted upon from all other universes (the faster expansion).

Mars_B4_Moon · 2022-05-28 10:13:54

New discovery about distant galaxies: Stars are heavier than we thought

https://www.spacedaily.com/reports/New_ … t_999.html

A team of University of Copenhagen astrophysicists has arrived at a major result regarding star populations beyond the Milky Way. The result could change our understanding of a wide range of astronomical phenomena, including the formation of black holes, supernovae and why galaxies die.

The Andromeda galaxy, our Milky Way's closest neighbor, is the most distant object in the sky that you can see with your unaided eye. Photo: Getty

For as long as humans have studied the heavens, how stars look in distant galaxies has been a mystery. In a study published in The Astrophysical Journal, a team of researchers at the University of Copenhagen's Niels Bohr Institute is doing away with previous understandings of stars beyond our own galaxy.

Since 1955, it has been assumed that the composition of stars in the universe's other galaxies is similar to that of the hundreds of billions of stars within our own - a mixture of massive, medium mass and low mass stars. But with the help of observations from 140,000 galaxies across the universe and a wide range of advanced models, the team has tested whether the same distribution of stars apparent in the Milky Way applies elsewhere. The answer is no. Stars in distant galaxies are typically more massive than those in our "local neighborhood". The finding has a major impact on what we think we know about the universe.

"The mass of stars tells us astronomers a lot. If you change mass, you also change the number of supernovae and black holes that arise out of massive stars. As such, our result means that we'll have to revise many of the things we once presumed, because distant galaxies look quite different from our own," says Albert Sneppen, a graduate student at the Niels Bohr Institute and first author of the study.

Mars_B4_Moon · 2023-05-18 13:03:39

Measurement of anti-3He nuclei absorption in matter and impact on their propagation in the Galaxy

https://www.nature.com/articles/s41567-022-01804-8

Mars_B4_Moon · 2023-08-17 03:36:40

JADES-GS-z13-0 is a high-redshift Lyman-break galaxy found by JWST on 29 September 2022. Spectroscopic observations by JWST's NIRSpec instrument in October 2022 confirmed the galaxy's redshift of z = 13.2 to a high accuracy, establishing it as the oldest and most distant spectroscopically-confirmed galaxy known as of 2022, with a light-travel distance (lookback time) of 13.6 billion years. GLASS-z12 formerly known as GLASS-z13 is a Lyman-break galaxy discovered by the Grism Lens-Amplified Survey from Space (GLASS) observing program using the James Webb Space Telescope's NIRCam in July 2022. GLASS-z12 has a light-travel distance (lookback time) of 13.6 billion years.However, due to the expansion of the universe, its present proper distance is 33.2 billion light-years.

Weakly interacting massive particles (WIMPs) one of the proposed candidates for dark matter

Did JWST just discover dark matter stars?

https://www.youtube.com/watch?v=zUhOL38346Y

A paper in April 2023 suggests that JADES-GS-z13-0 isn't in fact a galaxy, but a dark star with a mass of around a million times that of the Sun.

https://ui.adsabs.harvard.edu/abs/2023arXiv230401173I

another oldest Galaxy

https://www.newscientist.com/article/23 … -universe/

Last edited by Mars_B4_Moon (2023-08-17 03:49:43)

Mars_B4_Moon · 2023-09-13 06:29:26

Astronomers Observe Blobs of Dark Matter Down to a Scale of 30,000 Light-Years Across

https://www.universetoday.com/163143/as … rs-across/

Mars_B4_Moon · 2023-09-18 05:04:53

A New Technique Confirms the Universe is 69% Dark Energy, 31% Matter (Mostly Dark)
https://www.universetoday.com/163241/a- … stly-dark/

How much “stuff” is there in the Universe? You’d think it would be easy to figure out. But, it’s not. Astronomers add up what they can detect, and still find there’s more to the cosmos than they see. So, what’s “out there” and how do they account for it all?

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#1 2002-12-29 16:18:24

Re: Dark Matter - ???

#2 2002-12-31 21:05:34

Re: Dark Matter - ???

#3 2003-01-01 09:40:03

Re: Dark Matter - ???

#4 2003-01-01 13:10:37

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#5 2003-01-01 13:16:32

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#6 2003-01-01 14:11:54

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#7 2003-01-01 15:07:26

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#8 2003-01-01 15:48:38

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#9 2003-01-05 20:44:06

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#10 2003-01-13 23:09:58

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#11 2005-02-23 13:39:55

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#12 2005-03-04 09:45:30

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#13 2005-03-10 09:16:32

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#14 2005-03-19 09:23:40

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#15 2005-08-30 06:25:44

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#16 2005-11-23 06:57:55

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#17 2005-11-26 07:47:50

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#18 2007-08-17 01:19:03

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#19 2007-11-08 15:24:12

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#20 2007-11-08 19:13:13

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#21 2022-05-28 10:13:54

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#22 2023-05-18 13:03:39

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#23 2023-08-17 03:36:40

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#24 2023-09-13 06:29:26

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#25 2023-09-18 05:04:53

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