Dark Matter

[C1ay]

A related, thought provoking entry from Worldbook@NASA:

 

No one has yet discovered a black hole for certain. To prove that a compact object is a black hole, scientists would have to measure effects that only a black hole could produce. Two such effects would be a severe bending of a light beam and an extreme slowing of time. But astronomers have found compact objects that are almost certainly black holes. The astronomers refer to these objects simply as "black holes" in spite of the small amount of uncertainty.....

 

Most astronomers believe that the Milky Way Galaxy -- the galaxy in which our solar system is located -- contains millions of black holes. Scientists have found a number of black holes in the Milky Way....

 

Scientists believe that most galaxies have a supermassive black hole at the center. The mass of each of those objects is thought to be between 1 million and 1 billion solar masses. Astronomers suspect that supermassive black holes formed several billion years ago from gas that accumulated in the centers of the galaxies.

 

There is strong evidence that a supermassive black hole lies at the center of the Milky Way. Astronomers believe this black hole is a radio-wave source known as Sagittarius A* (SgrA*). The clearest indication that SgrA* is a supermassive black hole is the rapid movement of stars around it. The fastest of these stars appears to orbit SgrA* every 15.2 years at speeds that reach about 3,100 miles (5,000 kilometers) per second. The star's motion has led astronomers to conclude that an object several million times as massive as the sun must lie inside the star's orbit. The only known object that could be that massive and fit inside the star's orbit is a black hole....

[coldcreation]

A related, thought provoking entry from Worldbook@NASA:

 

As stated above, Newtonian mechanics seems to work well when applied to the solar system. But going up the scale of masses to galaxies, to clusters of galaxies, superclusters and ultimately the mass density of the universe as a whole, the less compelling and the more uncompromisingly large the deviation from reasonable interpretation.

 

How can this be if local physics is global physics? There are three answers to this question, only one of which must be correct:

 

1. There exists some form of undetectable non-baryonic dark matter or negative cosmic energy that like the Loch Ness Monster (affectionately known as Nessie or nessiteras rhombopteryx by serious aficionados, the legendary beast said to lurk in its peat-darkened depths of the massive loch) remains elusive and spurious.

2. Local physics differs markedly from global physics.

3. There is something missing from Newton’s law of motion (and from Kepler’s third law) both on local and global scales, but become increasingly noticeable going up the mass and scale factor—leading to and ending up in serious theoretical conflict with observations.

 

 

If you chose number three, you are most likely neither a cosmologist nor astronomy major. If number three was chosen you might wonder why GR with the cosmological constant is not brought into play to resolve the equilibrium calamity.

 

There is an instantaneous angular frequency by which satellite galaxies move around the center of potential of the halo (constant for circular orbits) and relative to the center of mass of the system (formed by both the satellite and the halo, from the center to the inner Lagrangian point of the potential), observed both in simulations and in the real world. There is a geometrical mathematical underpinning inherent in nature at all scales.

 

The inferrence of BHs or SMBHs in galactic nuclei is not required if indeed the cosmological constant is opporational on local scales (compatible with two-body systems, 3-body systems, multiple-body systems, the solar system, globular clusters, galaxies, clusters superclustes etc. Not to mention molecular scales.).

 

A galaxy, in many ways, is like a hurricane. What makes the molecules of water spin so quickly around the eye? Anyone?

 

Coldcreation

[questor]

the answer... what makes the electron spin around the nucleus? what makes the earth spin on its axis? what makes the earth spin around the sun? why is spin ubiquitous in the universe? perhaps for the same reason.

[questor]

i hope answers given here follow scientific methods and have or are being proved. when a human being matures. his cells are more numerous than when he is born. if electrons are orbiting or moving around his nuclei, where does extra the energy come from to

spin the extra electrons?

[CraigD]

…

3. There is something missing from Newton’s law of motion (and from Kepler’s third law) both on local and global scales, but become increasingly noticeable going up the mass and scale factor—leading to and ending up in serious theoretical conflict with observations.

 

If you chose number three, you are most likely neither a cosmologist nor astronomy major. If number three was chosen you might wonder why GR with the cosmological constant is not brought into play to resolve the equilibrium calamity.

This brings to mind something I’ve been meaning to ask you, as one of scienceforum’s recognized deep-thinkers-about-cosmology, coldcreation: are you aware of, and if so, what do you make of Cooperstock and Tieu’s recent paper claiming that the galaxy rotation problem (which you’re describing here) can be resolved without the need for MACHOs or MANCHOs* “simply” by a correct formalism using GR in place of Newton’s Universal Gravitation?

A galaxy, in many ways, is like a hurricane. What makes the molecules of water spin so quickly around the eye? Anyone?

I can’t resist a quiz! Water (and air, as well) spins so quickly around the eye of a hurricane because: 1) the eye contains an area of very low air pressure, causing the surrounding, higher-pressure areas to accelerate toward it; and 2) the disorderly motion of the air surrounding the air makes it much more likely that the inrushing air will not move straight into the eye, but be deflected by other inrushing air into a spiral path, producing the characteristic swirl pattern we see looking down on a hurricane. It is conceivable that a hurricane system might involve winds blowing straight in, then straight out, of its center (like waves from a stone dropped in a pool, or the motion of stars in a globular cluster) but so unlikely as to never occur.

 

:) In other ways, a galaxy is not like a hurricane. Even making many circuits around it, higher pressure air eventually reaches the eye of a hurricane, in far less time than it takes a hurricane to dissipate. Why do hurricanes not dissipate much more quickly than they do?

 

* MANCHO (my own acronym, I believe) = Non-Compact (possibly uniformly spread throught space) MACHO.

[Jay-qu]

i hope answers given here follow scientific methods and have or are being proved. when a human being matures. his cells are more numerous than when he is born. if electrons are orbiting or moving around his nuclei, where does extra the energy come from to

spin the extra electrons?

 

this is a seperate topic that has been discussed in another thread -> here

 

I dont understand what you mean by your acronym CraigD

[CraigD]

... dont understand what you mean by your acronym CraigD

”MACHO” stands for “MAssive Compact (galactic) Halo Object”, and is a widely used term for, to quote a wikipedia article, “any kind of astronomical body that might explain the apparent presence of dark matter in galaxy halos”. In reading about modern cosmology in general and the galaxy rotation problem in particular, I’ve not encountered an equally catchy term to describe dark matter in halos that isn’t compact, eg: clouds of ordinary dust and gas, massive neutrinos, etc. (and not claiming that any of these would suffice to resolve the galaxy rotation problem). MAHO, MADCHO, etc. didn’t scan very nicely, so I settled on MANCHO for “MAssive Non-Compact (galactic) Halo Object”.

 

Note that I’m making no claim that either MACHOs or MANCHOs actually exist, or resolve the problem, just trying to find useful terms to discuss it.

[Jay-qu]

I actually remember reading about them now, they where mentioned briefly along with WIMP's - weakly interacting massive particles

[emessay]

the answer... what makes the electron spin around the nucleus? what makes the earth spin on its axis? what makes the earth spin around the sun? why is spin ubiquitous in the universe? perhaps for the same reason.

 

They enjoy to follow galactic dance and we are real acrobats, even a bird-flu virus is a die-hard acrobat.

[cwes99_03]

Well, we can say a few things about black holes.

As far as I know, only one black hole has ever been found without any surrounding galaxy. It was only found because it coincided with a quasar.

Black holes form from a collapsing star. Stars don't form out in space on their own. Therefore, It would be extremely unlikely for a bunch of black holes to be sitting out in dark space. The only available way for this to occur, would be for them to devour all nearby material.

The only way to detect a truely black, black hole (one without any accretion disk around and just outside of its event horizon) would be galactic lensing. As this is a difficult study of the cosmos to find these galactic lenses, that would be a grand undertaking.

[damocles]

Well, we can say a few things about black holes.

As far as I know, only one black hole has ever been found without any surrounding galaxy. It was only found because it coincided with a quasar.

Black holes form from a collapsing star. Stars don't form out in space on their own. Therefore, It would be extremely unlikely for a bunch of black holes to be sitting out in dark space. The only available way for this to occur, would be for them to devour all nearby material.

The only way to detect a truely black, black hole (one without any accretion disk around and just outside of its event horizon) would be galactic lensing. As this is a difficult study of the cosmos to find these galactic lenses, that would be a grand undertaking.

 

This brings up a question I have.

 

Using the standard single bubble eruption from flatspace model; at the initial inflation, once transparency(as we understand it) came to that space, the fragmentation of unitary particles and forces progressed to the point where we were well into the helium formation stage of matter: would it be possible at that relatively young interval for local densities of matter to be; so great that much of it if not most of it(matter) would clump into hypermasses, and yet be distributed across the inflated space far enough apart that their local gravitation would be unable to overcome their initial recession rate from each other? Call it the "inverted microwaved popcorn" explanation of the missing mass?

 

Just a question.

 

Best wishes;

[CraigD]

… Using the standard single bubble eruption from flatspace model; at the initial inflation, once transparency(as we understand it) came to that space, the fragmentation of unitary particles and forces progressed to the point where we were well into the helium formation stage of matter: would it be possible at that relatively young interval for local densities of matter to be; so great that much of it if not most of it(matter) would clump into hypermasses, and yet be distributed across the inflated space far enough apart that their local gravitation would be unable to overcome their initial recession rate from each other? …

Not only is this possible, it’s been much discussed. The resolution of the question “why isn’t space full of little, primordial black holes?” contributed a large part to the stellar reputation of Steven Hawking, physicist and pop icon.

 

In short, Hawking’s resolution concludes that lots of little black holes were formed, but completely “evaporated” due to Hawking radiation almost immediately after they were formed. A 2.28*10^5 kg black hole evaporates in 1 second, and evaporation time is proportional to the cube of mass. Primordial black holes were around this size or smaller, so 13 billion years later, there’re none around.

 

:) A more practical implication of this conclusion is that we needn’t worry that messing around with imploding matter in bombs or particle accelerators will create a mini black hole that will fall to the center of the Earth and eat it up. (For a fictional treatment of this alarming possibility (and other Science fun), I recommend James Hogan’s ”Thrice Upon a Time”)

[coldcreation]

This brings to mind something I’ve been meaning to ask you, as one of scienceforum’s recognized deep-thinkers-about-cosmology, coldcreation: are you aware of, and if so, what do you make of Cooperstock and Tieu’s recent paper claiming that the galaxy rotation problem (which you’re describing here) can be resolved without the need for MACHOs or MANCHOs* “simply” by a correct formalism using GR in place of Newton’s Universal Gravitation?I can’t resist a quiz! Water (and air, as well) spins so quickly around the eye of a hurricane because: 1) the eye contains an area of very low air pressure, causing the surrounding, higher-pressure areas to accelerate toward it; and 2) the disorderly motion of the air surrounding the air makes it much more likely that the inrushing air will not move straight into the eye, but be deflected by other inrushing air into a spiral path, producing the characteristic swirl pattern we see looking down on a hurricane. It is conceivable that a hurricane system might involve winds blowing straight in, then straight out, of its center (like waves from a stone dropped in a pool, or the motion of stars in a globular cluster) but so unlikely as to never occur.

 

:) In other ways, a galaxy is not like a hurricane. Even making many circuits around it, higher pressure air eventually reaches the eye of a hurricane, in far less time than it takes a hurricane to dissipate. Why do hurricanes not dissipate much more quickly than they do?

 

* MANCHO (my own acronym, I believe) = Non-Compact (possibly uniformly spread throught space) MACHO.

 

I need a little time to read the pdf. Back later...

Until then, I have too a couple of acronyms, my own. Here is a selection: Doppler universe cannibalism and Hubble expansion (), degeneracy in the mass (), is dis info obsolete too? (?), Los Alamos Mother of all electrons (), Cosmic Radiation Anistropy Probe (), Jean’s instability sucking mechanism (), cosmic ubiquitous microwaves (), bleak unbelievable nonexistent gravity-hole (), automatic non-dynamical response to the onset of gynocratic nebulocity (), dubious ubiquitous delirious erogenous-zone (), super massless (), pussyish inactive massive particles (), With a miracle anything is possible ().

 

Coldcreation

[Tormod]

Until then, I have too a couple of acronyms, my own. Here is a selection: ...

 

AAFL (Acronyms Are For Loosers). :)

[damocles]

Not only is this possible, it’s been much discussed. The resolution of the question “why isn’t space full of little, primordial black holes?” contributed a large part to the stellar reputation of Steven Hawking, physicist and pop icon.

<snip>

 

So what is the limiter to the mass accretion that prevents huge hypermasses from forming at that early time in the inflation model?

 

Cheers;

[CraigD]

So what is the limiter to the mass accretion that prevents huge hypermasses from forming at that early time in the inflation model?

I’m not familiar enough with Hawking’s work to answer with authority. My guess is that there’s a reasonable possibility that some disuniformities – “clumps” – in the primordial universe resulted in many small primordial black holes falling together to create, if not hypermassive back holes, at least black holes massive enough to still be around.

 

The apparent high uniformity of the early universe, as measured by such things as the Cosmic Microwave Background Radiation, suggests that such clumping is not likely to non-existent, while the current, clumpy distribution of visible matter suggest that it is. I, and I suspect even full-time cosmologists, are guessing pretty wildly about phenomena dependent on a given uniformity or lack of uniformity of the early universe – the evidence is so difficult, indirect, and hard to reproduce. :)

[infamous]

I need a little time to read the pdf. Back later...

Until then, I have too a couple of acronyms, my own. Here is a selection: Doppler universe cannibalism and Hubble expansion (), degeneracy in the mass (), is dis info obsolete too? (?), Los Alamos Mother of all electrons (), Cosmic Radiation Anistropy Probe (), Jean’s instability sucking mechanism (), cosmic ubiquitous microwaves (), bleak unbelievable nonexistent gravity-hole (), automatic non-dynamical response to the onset of gynocratic nebulocity (), dubious ubiquitous delirious erogenous-zone (), super massless (), pussyish inactive massive particles (), With a miracle anything is possible ().

 

Coldcreation

I've edited this post because it showed a lack of respect for the individual it was directed at.