New study suggests tens of thousands of black holes exist in Milky Way's center

April 4, 2018, Columbia University
Credit: CC0 Public Domain

A Columbia University-led team of astrophysicists has discovered a dozen black holes gathered around Sagittarius A* (Sgr A*), the supermassive black hole in the center of the Milky Way Galaxy. The finding is the first to support a decades-old prediction, opening up myriad opportunities to better understand the universe.

"Everything you'd ever want to learn about the way big interact with little black holes, you can learn by studying this distribution," said Columbia Astrophysicist Chuck Hailey, co-director of the Columbia Astrophysics Lab and lead author on the study. "The Milky Way is really the only galaxy we have where we can study how supermassive black holes interact with little ones because we simply can't see their interactions in other galaxies. In a sense, this is the only laboratory we have to study this phenomenon."

The study appears in the April 5 issue of Nature.

For more than two decades, researchers have searched unsuccessfully for evidence to support a theory that thousands of black holes surround supermassive black holes (SMBHs) at the center of large galaxies.

"There are only about five dozen known black holes in the entire galaxy—100,000 light years wide—and there are supposed to be 10,000 to 20,000 of these things in a region just six light years wide that no one has been able to find," Hailey said, adding that extensive fruitless searches have been made for black holes around Sgr A*, the closest SMBH to Earth and therefore the easiest to study. "There hasn't been much credible evidence."

He explained that Sgr A* is surrounded by a halo of gas and dust that provides the perfect breeding ground for the birth of massive stars, which live, die and could turn into black holes there. Additionally, black holes from outside the halo are believed to fall under the influence of the SMBH as they lose their energy, causing them to be pulled into the vicinity of the SMBH, where they are held captive by its force.

While most of the trapped black holes remain isolated, some capture and bind to a passing star, forming a stellar binary. Researchers believe there is a heavy concentration of these isolated and mated black holes in the Galactic Center, forming a density cusp which gets more crowded as distance to the SMBH decreases.

In the past, failed attempts to find evidence of such a cusp have focused on looking for the bright burst of X-ray glow that sometimes occurs in black hole binaries

"It's an obvious way to want to look for black holes," Hailey said, "but the Galactic Center is so far away from Earth that those bursts are only strong and bright enough to see about once every 100 to 1,000 years." To detect black hole binaries then, Hailey and his colleagues realized they would need to look for the fainter, but steadier X-rays emitted when the binaries are in an inactive state.

"It would be so easy if black hole binaries routinely gave off big bursts like neutron star binaries do, but they don't, so we had to come up with another way to look for them," Hailey said. "Isolated, unmated black holes are just black—they don't do anything. So looking for isolated black holes is not a smart way to find them either. But when black holes mate with a low mass star, the marriage emits X-ray bursts that are weaker, but consistent and detectable. If we could find black holes that are coupled with low mass stars and we know what fraction of black holes will mate with low mass stars, we could scientifically infer the population of isolated black holes out there."

Hailey and colleagues turned to archival data from the Chandra X-ray Observatory to test their technique. They searched for X-ray signatures of black hole-low mass binaries in their inactive state and were able to find 12 within three light years, of Sgr A*. The researchers then analyzed the properties and spatial distribution of the identified binary systems and extrapolated from their observations that there must be anywhere from 300 to 500 black hole low-mass binaries and about 10,000 isolated black holes in the area surrounding Sgr A*.

"This finding confirms a major theory and the implications are many," Hailey said. "It is going to significantly advance gravitational wave research because knowing the number of black holes in the center of a typical galaxy can help in better predicting how many gravitational wave events may be associated with them. All the information astrophysicists need is at the center of the galaxy."

Hailey's co-authors on the paper include: Kaya Mori, Michael E. Berkowitz, and Benjamin J. Hord, all of Columbia University; Franz E. Bauer, of the Instituto de Astrofísica, Facultad de Física, Pontificia, Universidad Católica de Chile, Millennium Institute of Astrophysics, Vicuña Mackenna, and the Space Science Institute; and Jaesub Hong, of Harvard-Smithsonian Center for Astrophysics.

Explore further: Study shows first evidence of winds outside black holes throughout their mealtimes

More information: Charles J. Hailey et al, A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy, Nature (2018). DOI: 10.1038/nature25029

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Benni
2 / 5 (16) Apr 04, 2018
http://ircamera.a...nter.htm

Look in 7th & 10th photo frames from the top of the page of above link, it states:

"Here is a very deep, high resolution (1 arcsec) xray image of the Galactic Center -- the source elongated up and down just above and to the right of the center is Sgr A*, but it doesn't stand out at all. Even in X-rays, where we look to find stellar black holes, there is nothing to draw our attention to the supermassive black hole here."

Now from this article:

"Hailey said, adding that extensive fruitless searches have been made for black holes around Sgr A*, the closest SMBH to Earth and therefore the easiest to study. "There hasn't been much credible evidence."

Followup question for Hailly: If you can't find the most massive 3-4 million SM one that has been pre-supposed to exist at Sgr A*, why then would you even remotely suspect thousands more MUST exist?

Da Schneib
4.3 / 5 (17) Apr 04, 2018
@LenniTheLiar posts the same sorry excuse for "evidence" again, which has been repeatedly shown to be evidence of the exact opposite of its claims. Why do you bother, @LenniTheLiar? You were already shown on at least 4 threads to be lying about the evidence at the link you are posting, and had it explained carefully and extensively by some nice person. You are completely ignoring the actual claims the link you are posting makes and provides evidence for, by cherry picking from that link.

Stop lying. It's not going to work any better on this thread than it did on the last ones.
Benni
1.8 / 5 (16) Apr 04, 2018
Stop lying. It's not going to work any better on this thread than it did on the last ones


Pictures don't lie, learn to deal with the OBSERVATIONAL EVIDENCE & get out of the TUG Math of 19th century cosmology Schneibo.
Da Schneib
4.2 / 5 (15) Apr 04, 2018
Now, regarding this paper and article, this is an excellent example of the progress from conjecture, to hypothesis and a solid prediction, to verification of the prediction and solid evidence for a theory.

The conjecture: if there is indeed a SMBH at the galactic center, there should be an unusual number of black holes near it.
The hypothesis: if there are an unusual number of black holes near the galactic center, there should be an unusual number of black hole binaries. These should be detectable by analyzing archived X-ray observatory data that shows the galactic center.
The confirmation: the X-ray signatures were detected in the archived data.
The theory supported: there is a SMBH at the galactic center.

That's how science is done.

Pictures don't lie
Cherry-picking is lying. To paraphrase an old saw, pictures don't lie but liars cherry-pick pictures.

We done here?
dfjohnsonphd
4.3 / 5 (6) Apr 04, 2018
The article did mention it was difficult to detect "unmated black holes" that are not giving off radiation. One might suggest the core SMBH is currently not active in anyway, so it would not be giving a signal. From the article:

"Isolated, unmated black holes are just black—they don't do anything. So looking for isolated black holes is not a smart way to find them either."

Lacking a "mate", perhaps even SMBHs are "quiet" in X-rays, etc, suggesting they have found the core SMBH by alternate means. Clearly we know it is there.

Since stellar density, and therefore presumably "massive star" density increases as you approach the center of the galaxy, it is not unreasonable to suspect that the center would contain a large number of black holes. That number is clearly debatable. But his logic is not unreasonable as a model for BH density near the core.
dfjohnsonphd
4.6 / 5 (10) Apr 04, 2018
Wow, @Da Schneib. Did not realize what is going on here. Your posts were rapid fire as I was composing my first.

If what you say is true, liars are bad news in most places, and certainly not welcome in science. They should go to Washington, D.C. They love liars.

theredpill
5 / 5 (4) Apr 04, 2018
Black hole physics seems to be consistently lacking a complete description of the mechanics behind the observable and theorized events they are touted to be responsible for. "Additionally, black holes from outside the halo are believed to fall under the influence of the SMBH as they lose their energy, causing them to be pulled into the vicinity of the SMBH, where they are held captive by its force." This statement breeds the following questions: What stops them from continuing into the event horizon and holds them captive? The black hole's gravity (strongest local force) pulls them towards it but a stronger force than the black hole that is closer to it stops the advance and "holds it captive"? Additionally, when they speak of loss of "energy" are they talking about velocity? Or is there another kind of energy that acts as some sort of anti gravity field which, once spent allows the SMBH gravity to cause something it couldn't before said energy loss?

Benni
1.5 / 5 (15) Apr 04, 2018
Wow, @Da Schneib. Did not realize what is going on here. Your posts were rapid fire as I was composing my first.


.......because these 19th century TUG black hole cosmologists get a little testy when they are slapped up alongside the head with irrefutable OBSERVATIONAL EVIDENCE, they hate 21st century technology that utterly refutes their black hole TUG Math.

dfjohnsonphd
3.7 / 5 (3) Apr 04, 2018
@ theredpill. Check wiki on "ergosphere". You might find an answer to black hole energies there. Some of it involves rotation. Probably other ways to lose energy too.

We are not dealing with how to make beer here.......a tad more complex, some might suggest.
Da Schneib
4.3 / 5 (12) Apr 04, 2018
@LenniTheLiar, the fact that black holes occur in 17th century (duh, maybe you forgot Newton's TUG was published in 1686), 18th century (duh, maybe you forgot Mitchell's 1784 letter to Cavendish, and Laplace's 1796 book, both talking about dark stars, i.e. black holes), and 20th century (Schwartzchild's solution to General Relativity Theory that shows a solution with an event horizon, i.e. a black hole) gravity theories seems to show black holes exist. It doesn't appear anyone can make a gravity theory that doesn't have black holes; no one has so far.

Just sayin'. Maybe you got one. I bet it doesn't have any math.

And you're still lying about what the fact that black holes occur in TUG shows, and (of course) cherry-picking my statements about it to twist them to your lies.
dfjohnsonphd
4.5 / 5 (8) Apr 04, 2018
I am guessing the central SMBH is silent in X-rays due to the lack of signficant accretion.

It currently is not eating enough matter to create energies which produce such radiation. That is what the companion stars to smaller black holes provide.

This seems so simple to me, do I have something wrong here?!

dnatwork
1 / 5 (3) Apr 04, 2018
@dfjohnsonphd, I would suggest not picking sides in that particular fight.

My question is, if all those black holes are there swirling at presumably very high speed around the central SMBH (else they would simply fall into it), wouldn't that increase the gravity of the whole system? That is, doesn't the relative motion of an object add to the gravity that it generates by mass alone?

If so, is all that extra gravity accounted for in LCDM, before they turn to dark matter to explain any excess gravity?
Benni
1.3 / 5 (12) Apr 04, 2018
Just sayin'. Maybe you got one. I bet it doesn't have any math.


OBSERVATIONAL EVIDENCE found at:

http://ircamera.a...ter.htm, doesn't need math from any century, just some good old fashioned eyeballs in the belief that your eyes are not lying to you, but you do.
Da Schneib
4.4 / 5 (14) Apr 04, 2018
@dfjohnsonphd, seems to me you've got that right. And if you check http://ircamera.a...nter.htm you will find a picture that shows the SMBH at the Milky Way galactic center accreting something about the mass of Mercury, and lighting up while it does it. Text search the page for "mercury."

@LenniTheLiar used to use this link, but has changed over to the one in this thread because the old one had too much evidence that has to be ignored. Got challenged on it, too. I can dig up the old threads where this older link was used if you like but I expect you get the idea how deceptive this person is from this evidence alone.
Da Schneib
4.4 / 5 (14) Apr 04, 2018
@LenniTheLiar you just got caught substituting one link from the same source for another, because you are trying to lie about what the link says. Nice try, but you're lying (and cherry-picking) again. The link with *ALL* the evidence is: http://ircamera.a...nter.htm

You really got upset when your own link got used against you, didn't you?

How transparent. And how absolutely typical of your usual deceptive tactics.

If you're telling the truth, how come you need all these tactics?

Oh and BTW I notice you don't seem to have any gravity theory at all, and tried to sweep it under the carpet and pretend I never asked. Your transparent attempts at deceit go on and on, don't they?
dnatwork
2 / 5 (4) Apr 04, 2018
If so, is all that extra gravity accounted for in LCDM, before they turn to dark matter to explain any excess gravity?


Maybe that diffuse galaxy last week that seemed to have no dark matter was diffuse because it lacks an SMBH, and thus has no swarm of orbiting black holes to generate the appearance of dark matter.

And the Bullet Cluster: Maybe the apparent dark matter halo separated from the galaxy because the SMBH and its companion BH's had more momentum than the regular stars, so the regular stars were slowed down more by the drag of the collision.

And then you'd have a rational explanation for why "dark matter" is always found around regular matter, even though they necessarily don't interact, except somehow by gravity, sometimes. The lack of which explanation is the biggest problem for LCDM (besides the fact that every candidate particle has been not found or outright proven not to exist). It would just arise from the configuration of normal matter.
Da Schneib
4.2 / 5 (10) Apr 04, 2018
@dn, the flaw in your conjecture is that the mass of the SMBH and all the black holes in the galactic center are spit in the ocean compared to the mass of the galaxy, whereas the mass required to explain observed rotation curves is about five times that mass. The deficit here is at least an order of magnitude if not many orders of magnitude. The same applies to the Bullet Cluster. As I often ask, where's the beef?
Benni
1.7 / 5 (12) Apr 04, 2018
And then you'd have a rational explanation for why "dark matter" is always found around regular matter


........show us the OBSERVATIONAL EVIDENCE.
Benni
1.7 / 5 (12) Apr 04, 2018
As I often ask, where's the beef?
.......try OBSERVATIONAL EVIDENCE, a much more succinct terminology.

How transparent. And how absolutely typical of your usual deceptive tactics.


......OBSERVATIONAL EVIDENCE is not a deceptive tactic, it's the best that exists.
dfjohnsonphd
4.6 / 5 (9) Apr 04, 2018
@dnatwork, it is hard not to pick sides when one appears to be playing in a sand box and the other is playing with real science. Sand boxers post little useful information. They are pretty easy to pick out from the crowd.

Show us some BRAINS!!

Da Schneib
4.2 / 5 (10) Apr 04, 2018
@LenniTheLiar, cherry-picked observational evidence, which you have now been shown to be using both by ignoring inconvenient evidence in your previous link, and by changing links to one that doesn't contain the evidence you find inconvenient, is plain simple lying.

The OBSERVATIONAL EVIDENCE [sic, sorry for the shouting] says you're lying. And that's both noting your behavior (first ignoring the evidence at the link you provided, then switching to a link that doesn't contain that evidence), and noting the real evidence at the link you yourself first provided that you are ignoring by cherry-picking around it.
dfjohnsonphd
4.3 / 5 (6) Apr 04, 2018
Question for all (except the liar):

Does the SMBH at Sgr* have rotational kinetics? As a Biochemist, I am straying a tad out of my field.

@Da Schneib I get the idea how deceptive this person is from THE LACK OF EVIDENCE alone. Nothing is more revealing than irrational tripe. (Is that redundant?)
Benni
1.4 / 5 (10) Apr 04, 2018
@dnatwork, it is hard not to pick sides when one appears to be playing in a sand box and the other is playing with real science. Sand boxers post little useful information. They are pretty easy to pick out from the crowd. Show us some BRAINS!!


See Schneibo, a challenge to you to dump 19th century TUG Math for hypothesizing BHs and moving into 21st century technology that breaks the theory at:

http://ircamera.a...nter.htm

Remember when you, jonesy, RNP were going off on those long disertations a few weeks ago trying to tell readers there existed no pictorial evidence as this link clearly depicts there is? You went apoplectic in your rant that there existed no technology that provides the resolution as is clearly in evident at this site........my, how short your memory......hmmmm, just maybe that's it, welcome to 21st century technology.
Da Schneib
4.3 / 5 (12) Apr 04, 2018
@LenniTheLiar, the 17th century TUG got us to the Moon just fine. The corrections GRT would have added were many orders of magnitude smaller than the corrections for many-body physics under the TUG. Your inability to understand a gravity theory from the 17th century does not bode well for your pretense of understanding any gravity theory at all, much less GRT.

And now you're lying about what evidence was presented to you, and I note that you do not mention the kind individual who explained exactly how you were cherry-picking evidence, and what the evidence you refused to even acknowledge existed and tried to eliminate by switching links really means as opposed to your lies about it.

You really are a disgusting individual, and the more you post the more apparent it becomes that you do not actually believe what you are posting. You're nothing but a troll.
Da Schneib
4.6 / 5 (10) Apr 04, 2018
Question for all (except the liar):

Does the SMBH at Sgr* have rotational kinetics? As a Biochemist, I am straying a tad out of my field.
It almost certainly does, but nothing much that we have the resolution to see at this time with the available instrumentation approaches it closely enough to be strongly affected by those rotational effects. To get an idea of these effects, go look up articles on tides, gravitomagnetism, and frame-dragging and geodetic precession. This Wikipedia article discusses some of this, and you'll get more following links from it: https://en.wikipe...agnetism Tidal effects are discussed separately.
Benni
1.3 / 5 (12) Apr 04, 2018
You really are a disgusting individual, and the more you post the more apparent it becomes that you do not actually believe what you are posting. You're nothing but a troll.


Schneibo, you're the one who insisted that pictorial evidence found at http://ircamera.a...nter.htm did not exist. Hey, changed your mind yet? Or do you still believe "eyes can lie"?
Benni
1.3 / 5 (12) Apr 04, 2018
Question for all (except the liar):

Does the SMBH at Sgr* have rotational kinetics? As a Biochemist, I am straying a tad out of my field.


Here's an OBSERVATIONAL suggestion for you, just go to http://ircamera.a...nter.htm & locate the BH & figure it out for yourself. Once you locate SgrA* it wouldn't be hard to figure out from the extent of its' accretion disc. Uh, you do know what an accretion disc is? No matter, we at least know from OBSERVATIONAL EVIDENCE there is no accretion disc at SgrA*, so your "rotational kinetics" question is pointless.

Da Schneib
4.3 / 5 (12) Apr 04, 2018
@LenniTheLiar, you ignored the parts of the original link at http://ircamera.a...nter.htm that you didn't like, and then you substituted your new link that doesn't have the evidence you didn't like.

Why should anyone ever believe anything you say ever again? You are a liar, and you keep on lying, squirming, lying, cherry-picking, lying, trolling, lying, substituting evidence, lying, whining, lying, pretending you know anything about physics or math, lying, and avoiding questions you have no answers for.

Now go troll someplace else, @LenniTheLyingTroll.
theredpill
not rated yet Apr 04, 2018
@dfjohnsonphd - The section about the ergosphere (dissipation of rotational energy) made the conclusion that the lost energy is responsible for the inward migration even more confusing. In order to halt said inward migration if that was the mechanism responsible, the migrating BH would have to "spin back up" in order to stop the inward migration would it not? The question wasn't about "how" the energy is lost so much as the conclusion that it was the loss of energy that initiated the migration...because the migration then stopped as per the quote I was addressing. Yes, making beer is easier than comprehending this.
Da Schneib
4.5 / 5 (8) Apr 04, 2018
Black hole physics seems to be consistently lacking a complete description of the mechanics behind the observable and theorized events they are touted to be responsible for.
Hmmmm, I guess I'm not quite clear on what exact observable and theorized events you are talking about, and the remainder of your post didn't make it clear. Let's review:

...black holes from outside the halo are believed to fall under the influence of the SMBH as they lose their energy, causing them to be pulled into the vicinity of the SMBH, where they are held captive by its force.
What stops them from continuing into the event horizon and holds them captive?
Momentum and orbital mechanics. And it's not clear they're stopped; they may just be slowed down. And what holds them captive is gravity. Just like the stars orbiting the SMBH. I'm not clear on what observable you say don't have a complete description here. Momentum, orbital mechanics, and gravity seem pretty complete to me.
[contd]
Da Schneib
4.6 / 5 (9) Apr 04, 2018
[contd]
The black hole's gravity (strongest local force) pulls them towards it but a stronger force than the black hole that is closer to it stops the advance and "holds it captive"?
In fact you're forgetting that there is a whole galaxy far more massive than the SMBH surrounding the galactic center. The SMBH's gravity is only the "strongest local force" in its immediate vicinity, which is about the size of our inner Solar System, around 10 light seconds. These black holes are light years and tens of light years from the SMBH, which is many orders of magnitude farther than that, and remembering that gravity is an inverse square force this equates to many, many orders of magnitude weaker.

Again, I don't see any support for your claim that there is any lack of a complete description. You're just not aware of the real effects here.

[contd]
Da Schneib
4.6 / 5 (9) Apr 04, 2018
[contd]
when they speak of loss of "energy" are they talking about velocity?
Gravitational potential energy is what they're talking about, and it is (as always) converted into kinetic energy. This is one of the laws of orbital mechanics I spoke of above.

And I'm still not clear on how this supports your claim of a lack of a complete description. As with your unawareness of the strength of gravity and the size of the galactic center, you're unfamiliar with orbital mechanics.

These things can indeed be fully explained but you'd do well to study gravity physics, with particular attention to how inverse square laws cause unexpected scaling that you need to take into account, and orbital mechanics with particular attention to Kepler's laws. This forum is probably not a good place to have that all explained to you, since both are pretty complex subjects. But if, after looking into those things, you still have questions, this is probably a pretty good place to ask them.
dfjohnsonphd
3.9 / 5 (7) Apr 04, 2018
" Uh, you do know what an accretion disc is?"

Somebody on this thread knows just enough to be dangerous. Never question what I know or don't know. That could be a very big mistake. I forgot more in the last day than you ever knew in your entire miserable life.

So quit throwing sand from your box into the community's Vaseline, dude.

Except for one of us, we should simply ignore the child and try to move on.
dfjohnsonphd
4.2 / 5 (5) Apr 04, 2018
As some have postulated, primordial black holes (PBHs) were the "seeds" from which galaxies grew.

Is there any experimental evidence for primordial black holes?

The most evolved galaxies (ellipticals) have some of the largest SMBHs. Does this suggest that the evolutionary stages of many galaxies relate to the initial size of such potential PBHs. Grand spirals starting with much smaller PBHs, etc.

The vast number of variant galaxies, from elliptical to grand spirals indicates a primordial origin to their "current" appearance. The nearby Virgo Cluster (in which we are a back water) clearly demonstrates these galactic variants are not just from the distant past..
granville583762
3.4 / 5 (5) Apr 04, 2018
Blackholes are very rare

Stars are on average are 7 Lys apart, require just one orbit of the galaxy for 2 stars to counteract their gravity to keep the stars apart, effectively all stars are in a 250million year binary orbit, which is why there is no darkmatter in galaxies, when one of stars forms a blackhole its less massive than its star (it ejects matter), it is gravitationally weaker and as stars are in a 250million year binary orbit which is why no star has ever grazed our Sun. Stars almost never come into contact and the chances of becoming a blackhole is less than 2 stars colliding which such supernova an event will not go unnoticed. Blackholes are very rare and when they do form their nearest star on average is 7Lys away and because its gravity is weaker and it is in 7Lyr radius 250million year binary obit as all stars are it cannot get near other stars, just as no star has ever grazed our Sun.
Benni
1.3 / 5 (13) Apr 04, 2018
Uh, you do know what an accretion disc is?"

Somebody on this thread knows just enough to be dangerous. Never question what I know or don't know. That could be a very big mistake. I forgot more in the last day than you ever knew in your entire miserable life.
So quit throwing sand from your box into the community's Vaseline, dude.
Except for one of us, we should simply ignore the child and try to move on.


Have you ever seen a Differential Equation you could solve? I do it almost everyday what with having gotten a pretty good education during the six years I spent in Engineering school majoring in Nuclear/Electrical Engineering plus almost two years of continuing education credits beyond that, & all you are is a Bio-Chemist?

Maybe you can explain to the mis-educated what makes you such an authority about your tirade on me? Do you have any concept of the term OBSERVATIONAL EVIDENCE? The evidence is you're not moving that concept from bio-chemistry to outer space.
jonesdave
3.7 / 5 (15) Apr 04, 2018
Have you ever seen a Differential Equation you could solve? I do it almost everyday what with having gotten a pretty good education during the six years I spent in Engineering school majoring in Nuclear/Electrical Engineering plus almost two years of continuing education credits beyond that, & all you are is a Bio-Chemist?


Bull***t. Mr. Dunning-Kruger here couldn't even solve the equation for the Schwarzschild radius! Stuffed it up horribly. The guy is a waste of space, and knows zilch about any scientific subject. Just another Walter Mitty. Ignore the loon.

Benni
1.4 / 5 (10) Apr 04, 2018
Have you ever seen a Differential Equation you could solve? I do it almost everyday what with having gotten a pretty good education during the six years I spent in Engineering school majoring in Nuclear/Electrical Engineering plus almost two years of continuing education credits beyond that, & all you are is a Bio-Chemist?


Bull***t. Mr. Dunning-Kruger here couldn't even solve the equation for the Schwarzschild radius! Stuffed it up horribly. The guy is a waste of space, and knows zilch about any scientific subject. Just another Walter Mitty. Ignore the loon.


Well,well, well, finally you show up, the guy who has had so much recall difficulty recalling his math education, telling us he couldn't remember if he had Differential Equations in his high school algebra class or if it was that one year stint at Uni Auckland there in NZ.

Let me guess again, your major at Uni was: Name Calling Tirades......but why only a year? Even that was too tough?
Da Schneib
4.3 / 5 (11) Apr 04, 2018
Just FYI, @dfj, one of the earliest lies @LenniTheLiar told was claiming to be a nuclear engineer and right after that came claims to be able to solve DEs. Upon being presented with questions a nuke should be able to answer, and with systems of PDEs to solve, this individual proved to be incapable either of answering the questions or solving the systems of equations.

Do feel free to test the DE stuff for yourself and not just take my word for it; assuming your handle is honest (and I do), I cannot imagine a biochemist with a doctorate not being very familiar with calculus at a level far higher than that.

On edit: and considering the current types of research being done in biochem I expect you probably know more nuclear physics than this individual as well. ;)
jonesdave
3.7 / 5 (12) Apr 04, 2018
OK, here is our nuclear engineer having to guess at the Schwarzschild radius, because he couln't do a simple equation! Followed by me having to correct the Dunning-Kruger infected loon. From:

https://phys.org/...big.html

Posts all collected together in image format, here:

http://www.imageb...08120763

I suggest people save the image, and the link to the thread above, and post it every time Benji pulld out his D-K inspired lies about being a nuclear engineer, and knowing how to do DEs!
jonesdave
3.5 / 5 (13) Apr 04, 2018
I'm still wondering if Benni has cleaned the crayon off his monitor, after brilliantly proving that the stars at the galactic centre weren't orbiting a central mass! I kid you not people. Maybe I'll try to locate that post as well. Poor old Benni - science really isn't his strong point. I suspect some sort of mental illness, in which case we shouldn't be too hard on him!
Benni
1.7 / 5 (12) Apr 04, 2018
On edit: and considering the current types of research being done in biochem I expect you probably know more nuclear physics than this individual as well.


Well Schneibo, I'd ask him the same question I asked you a short time back about the decay rate of a free neutron, and what with a neutron having a decay rate of 15 minutes before it decays into a proton, electron & neutrino, how does that decay rate allot enough time for a supernova to collapse into a neutron star. You stumbled & bumbled around with the usual suspects in the rant brigade & never answered the question.

To begin with, you never knew a free neutron is stable for ONLY 15 minutes until I pointed it out. Then I pointed out that gravitational collapse in a SN is a process of days, months & years. So let's just see how your name calling bio-chemist cohort manages neutron decay in the formation of neutron stars if you think he's so damn smart about nuclear physics. Think he'll try that ND model?
jonesdave
4 / 5 (12) Apr 04, 2018
.....how does that decay rate allot enough time for a supernova to collapse into a neutron star.


Because there is no lower energy state to decay into. A neutron star is not built of neutrons alone: there is a significant admixture of protons and electrons. And this admixture of electrons is what explains neutron stability. The density of those electrons is so high, that they are degenerate, i.e. they occupy all low energy states. The maximal energy of an electron created in a neutron decay is 0.78 MeV. If all possible electron states up to this energy are occupied, a neutron can't decay, because there is "no place" for an extra electron.

https://www.quora...ar-decay
dfjohnsonphd
5 / 5 (9) Apr 04, 2018
@Da Schneib, read enough on this thread to realize that you and some others at this point are just bouncing the rubble on the child. Are you now trying to micronize that rubble? What is the point? At least leave him the sand in his box. He might have a hissy fit if you don't. Hmmmm, perhaps you should keep it up, but it is all becoming redundant.

Look, now he is bringing in some nonsense from Auckland. His posts are so trite that I feel no need to assist in this heavy bombardment.

Thanks for that link on the Galactic Center. Quite remarkable. And empirical data to boot. Very impressive.

cont.
dfjohnsonphd
5 / 5 (7) Apr 04, 2018
Regards DEs and other advanced math, most people in life sciences do not require such calculations anymore. Most of this stuff is handled by advanced instruments, like NMR, ESR, Mass Spec, Gamma etc. counters, Diffraction Crystallography, etc. Such instruments spit out the data from programs that use lots of calculus, freeing us to dream up and design experiments regarding the nature and interactions of large molecular complexes, like those involved with gene expression and means of controlling it. I had two semesters of Calc, and use it on very rare occasion. I am an experimentalist, not a theorist.

Cosmology cannot be conducted without mathematics as much of it is theoretical, and based frequently on WAGs (wild ass guesses). Math offers the most valuable refuge for such research. In this regard, physics and biochemistry have almost nothing in common.

cont.
dfjohnsonphd
5 / 5 (6) Apr 04, 2018
final:

I only dabble in cosmology as it suites me and time allows. Purifying large molecular complexes to form crystals for structural analysis by X-ray diffraction is difficult enough. Ascribing these structures to functionality is where the brain work comes in. And here are thousands of them.

None of it can be described even remotely by math. This is strictly about molecular interactions of the highest order. To close, there is no more complex physical phenomena in the universe than the simplest microbe. Defining the complete mechanism of even one life form is an accomplishment one can only dream of.

The abiotic origin of life is a puzzle I will pose to all who read this. If you come up with the answer, you will make even Einstein take a back seat.
dfjohnsonphd
5 / 5 (5) Apr 04, 2018
@ jonesdave, thanks for the brief on neutron stars. Quite remarkable. I was amazed to just recently learn that a free neutron has a half-life of around 15 minutes. That was a real shock. I knew proton decay was postulated, but never imagined a free neutron was so unstable.

Anybody want to get into proton decay? :o)

Still hoping for suggestions on primordial black holes. :o(

Da Schneib
4.5 / 5 (8) Apr 04, 2018
Heh, @dfj, sometimes I keep @Lenni on ignore, but occasionally I get bent enough to take off the ignore and give some 1s and arguments, though there's little that hasn't already been said as you rightly point out.

That's interesting about the math. I guess all the heavy math lifting has been done in more basic papers so you can just reference them and let it go at that. Working with high level molecular structures and figuring out their functionality as you do, I guess I can see why you wouldn't need the really heavy math. I expect you prolly use some statistics though, am I right?

My wife has a Master's in molecular biology from 30 or 40 years ago, and I try to keep up with developments and have read some of her books (mostly Crick "The Molecular Biology of the Gene") but I'm certainly no expert. More in a minute.
Da Schneib
5 / 5 (6) Apr 04, 2018
@dfj, neutrons can decay because an up quark weighs less than a down quark; a proton is two ups and a down, and a neutron is two downs and an up. So one of the downs can decay into an up, fixing up the electric charge and weak hypercharge by emitting a W-, and then the W- decays into an electron antineutrino and an electron. The electron carries off the electric charge, and the antineutrino carries off the weak hypercharge. There is a net energy loss to the electron and antineutrino, and the proton weighs less than the neutron, so all the books are balanced.

Now, when we talk about proton decay, there is no lighter quark for an up to decay into, and three ups aren't allowed, so any decay here has to be outside the Standard Model of Particle Physics (SM for short). The most expected path is to a neutral pion and a positron, though there are other possibilities. All experiments to detect this have failed. Hyper-Kamiokande is expected to start up about 2025 or so.
[contd]
Da Schneib
5 / 5 (6) Apr 04, 2018
[contd]
Given the extension of the minimum proton decay to (perhaps beyond) 10^36 years, experimentalists have quieted down on proton decay. Current popular speculation now has quantum gravity providing a route for proton decay rather than the earlier SUSY GUT proton decay models. No one knows what this would look like so it's difficult or impossible to propose an experiment to detect it.

I suspect there is a missing ingredient for proton decay to occur, one that was present at the very high energies in the early universe and absent today, but that's pure speculation on my part.
Osiris1
5 / 5 (2) Apr 04, 2018
Seems we have people that I will not name who do not read the entire article before commenting. I had, God rest her Soul, an ex-mother in law that ran a motel in the dim past when velociraptors roamed the earth who posted a cartoon that never loses its relevance:

"ENGAGE BRAIN BEFORE PUTTING MOUTH IN GEAR"
Da Schneib
5 / 5 (6) Apr 04, 2018
And finally moving on to primordial BHs, there is neither experimental nor observational evidence for them. There are some theoretical considerations that make them interesting, but certainly nothing conclusive. Every so often someone comes up with a conjecture, but so far no hypotheses with testable predictions.

Galactic evolution, and morphology and dynamics, also are still at the conjectural stage. Back about 10 or 20 years ago or longer, there was a lot of talk about multiple spirals at different angles combining to form ellipticals, but this never panned out in the dynamics simulations so it's been largely abandoned. Most models now have ellipticals evolving on their own from scratch. I don't know what the state of the current dynamical models in this area is. Models of evolution of spirals are a bit more concrete, with most models now having spirals grow by ingesting small irregulars.

I'll look and see if you got some good answers to all your questions in a bit.
Benni
1.4 / 5 (10) Apr 04, 2018
I was amazed to just recently learn that a free neutron has a half-life of around 15 minutes.


@fjohnsonphd: Where did you learn that? I've never heard of it......care to quote your recent source?

Oh, that quora thing jonesy put you onto, none of that stuff is found in nuclear physics & can't be verified in the Large Hadron Collider, I know I use their data on a semiregular basis.
jonesdave
3.3 / 5 (12) Apr 04, 2018
I was amazed to just recently learn that a free neutron has a half-life of around 15 minutes.


@fjohnsonphd: Where did you learn that? I've never heard of it......care to quote your recent source?

Oh, that quora thing jonesy put you onto, none of that stuff is found in nuclear physics & can't be verified in the Large Hadron Collider, I know I use their data on a semiregular basis.


As he said, he isn't an astrophysicist. If he was, then he'd have learned about electron degeneracy pressure in the first year of undergrad study.
Da Schneib
4.5 / 5 (8) Apr 04, 2018
Oh for cryin' out loud, now @Lenni is lying about free neutron decay? You gotta be kiddin me, that's from like the 1940s or something like that. And this idiot claims to be a nuclear engineer? Absolutely no friggin way at all evar.
Benni
2 / 5 (8) Apr 04, 2018
I was amazed to just recently learn that a free neutron has a half-life of around 15 minutes.


@fjohnsonphd: Where did you learn that? I've never heard of it......care to quote your recent source?

Oh, that quora thing jonesy put you onto, none of that stuff is found in nuclear physics & can't be verified in the Large Hadron Collider, I know I use their data on a semiregular basis.


As he said, he isn't an astrophysicist. If he was, then he'd have learned about electron degeneracy pressure in the first year of undergrad study.
.........you're getting your particles mixed up, neutrons are not electrons, basic 2nd semester physics. If you'd have had even the slightest inkling of what you were talking about you would have used NEUTRON DEGENERACY, not "electron degeneracy".......your're as confused about subatomic particles as you are about your memory recollection for those Differential Equations you told us you studied in Algebra class.
jonesdave
3.5 / 5 (13) Apr 04, 2018
.........you're getting your particles mixed up, neutrons are not electrons..


I know, you idiot. If you are going to learn about neutron degeneracy, which you obviously didn't know about, otherwise you wouldn't have been prattling on about this 15 minutes nonsense, then you have to start with electron degeneracy pressure, which is analogous. It's all part of the evolution of stars at the end of their lives, depending on mass. Chandrasekhar, Pauli, etc.
Anonym642864
2.3 / 5 (3) Apr 04, 2018
To my mind the life cycle of star starts from luminosity due fusion of Hydrogen to Helium and vice versa to Red giant, to white Dwarf to Neutron star and finally so called Black- Hole. But to my mind the moment neutron star is devoid of proton i.e alpha ray neutron star bursts and the new star starts forming i.e condensation of dust cloud.
jonesdave
2.7 / 5 (7) Apr 04, 2018
To my mind the life cycle of star starts from luminosity due fusion of Hydrogen to Helium........


True enough, but I did qualify it by saying 'evolution of stars at the end of their lives.'
Da Schneib
4.4 / 5 (7) Apr 04, 2018
Hey @dfj, I think I posted this link on the wrong thread for you. I promised to look this up earlier today: http://math.ucr.e...ies.html

This article quite early on, in the first couple of pages, discusses the hyperbolic trigonometric form of the Lorentz transformation, and this is vital because it then relates this to the ordinary Galilean rotation transformation using ordinary trigonometry. Once you understand this you will see why physicists treat velocity as a rotation in the time axis, which leads directly into an understanding of time that is quite different from what you are used to. This is the Minkowski view of spacetime. Take a look and ask 'em if you got 'em.
dfjohnsonphd
4.4 / 5 (7) Apr 05, 2018
The child has really exposed himself to more heavy bombardment.

"Absolutely no friggin way at all ever" is right.

Must have been reading about nuclear weapon design when I stumbled across the half-life of a free neutron. I am really big on nukes. They are some of the most amazing things that the mind of man ever invented. Almost all done by slide-rules and big brains. And N decay almost certainly was determined back in the 40s. Totally remarkable. Still reading through mounds of nuke stuff

Thanks for brief on neutron/proton decay. I understood the neutron decay with quarks but did not follow up with protons. Another one of my works in waiting.

I still love the notion of primordial black holes. Seem like offspring of the Big Bang.

And it is gas poor vs gas rich notions of various galactic forms that keeps me thinking about that. Even with globular clusters, many nearly as old as we think the universe is. Wild stuff.
dfjohnsonphd
4 / 5 (4) Apr 05, 2018
Gad zooks DS, don't pile a whole lot more on me right now. Still looking at that other stuff you gave me. Feel like I'm caught in some frame-dragging phase by a massive black hole with a high spin rate. Still am amazed by that aspect too. Frame-dragging, What a concept.
dfjohnsonphd
5 / 5 (2) Apr 05, 2018
Anybody with any ideas about globular cluster formation. They are somewhat enigmatic to the rest of the universe's star formation regions. Why so many is such a small space, and most very ancient. I look at images of Omega Centauri and my mind gets numb at the stellar density. Any with black holes at their cores?
Da Schneib
4.3 / 5 (6) Apr 05, 2018
Here, I was taking a break and saw your question about globular clusters. I believe there are some with black holes. Here's a paper I'm about to read: https://arxiv.org...3101.pdf

Accepted and published in Monthly Notices of the Royal Astronomical Society, so peer reviewed and a pretty good source. Enjoy.
dfjohnsonphd
5 / 5 (3) Apr 05, 2018
Thanks for the link on GCs. Looking at it now. Lots of speculation, but some good history too. I am surprised they are bringing dark matter so easily into the picture. Speculation on top of speculation is not good for the senses, nor does it make for good science. Grain of salt or two.

At least I work with things that you can see and touch. They are now getting direct imaging at atomic resolution of macromolecular protein binding sites with scanning tunneling microscopes, if I remember that story correctly.

The time lines on discovery etc. of neutron decay was a tough find, but well worth it. You have got to check this out :

http://www.int.wa...Nico.pdf

Free neutron decay was discovered in 1948 by Snell and Miller at Oak Ridge. Remarkable stuff.
yep
1.4 / 5 (9) Apr 05, 2018
Nice circle jerk going on here. The only thing dumber then one black hole is ten thousand. Math is worthless as empirical evidence wankers. GIGO
Luke3124
5 / 5 (3) Apr 05, 2018
I am a biotech student so this question might be a bit silly. From my basic understanding of black holes the gravity is so great that even light (electromagnetic radiation) can escape from them, so i was wondering how there could be any x-rays to detect from these mated blackholes?
antialias_physorg
4.3 / 5 (12) Apr 05, 2018
so i was wondering how there could be any x-rays to detect from these mated blackholes?

The x-rays aren't created inside the black hole. They are created by the infalling matter before it hits the event horizon. Black holes that do not feed don't emanate anything (except Hawking radiation, but that is very weak).

And yes: the construct "emanating from a black hole" is misleading. It should be more precisely framed as "emanating from the region of the black hole". But black holes are, generally, very small so looks the same.

Note also that if you want to be super-picky the event horizon isn't, strictly speaking, part of a black hole, either (although we mostly use the term that way). The black hole is the mass energy that creates the spacetime curvature (i.e. the -possibly- singularity at the center). The event horizon is just a set distance from that entity at which some criterion is fulfilled (viz.: escape velocity equal to the speed of light)
434a
4.4 / 5 (7) Apr 05, 2018
I am a biotech student so this question might be a bit silly. From my basic understanding of black holes the gravity is so great that even light (electromagnetic radiation) can escape from them, so i was wondering how there could be any x-rays to detect from these mated blackholes?


Not a silly question.
Basically, the infalling matter heats up due to friction. The collision of the matter produces photons but the extreme temperature - millions of degrees C - of the matter means those photons are released with a frequency we know as x-rays.

In short the x-rays are released before the matter is consumed by the blackhole. That's why blackholes that aren't feeding are invisible in the electromagnetic spectrum.

http://chandra.ha...ays.html

http://astronomy....Binaries

http://astronomy....Binaries
granville583762
4 / 5 (4) Apr 05, 2018
A light radius star is no bigger than R=2GM/C*
Light radius stars (blackholes) eject half the mass they take inside their light radius (event horizon) and eject it out of their light radius in their spin axis-outflow star forming Fermi-Bubble 23,000Ly clouds above and below their galaxy.
I've only heard every one saying light radius stars emanate nothing but Hawking radiation, the observations show light radius stars over snacking regurgitating their lunch through their light radius out of their spin axis out flows. Thanks for correcting Hawking radiation to only starving light radius stars.


antialias_physorg> Black holes that do not feed don't emanate anything (except Hawking radiation, but that is very weak).


Benni
2.1 / 5 (11) Apr 05, 2018
Free neutron decay was discovered in 1948 by Snell and Miller at Oak Ridge. Remarkable stuff.


.....and you will note that neutrons do not have a "half-life" of 15 minutes, they have a life span of 15 minutes. Every neutron that comes into existence in the free state will within 15 minutes decay into a proton, an electron, and a neutrino, no other condition for a neutron has ever been observed beyond 15 minutes of duration time.

So, how can a particle that has an OBSERVED life span of 15 minutes coalesce to forn a so-called NEUTRON STAR leading to the formation of a BLACK HOLE? The speculation is this occurs during the process of GRAVITATIONAL COLLAPSE when a star goes super novae.

The problem with the GRAVITATIONAL COLLAPSE theory preserving free neutrons from decaying within 15 minutes due to fictional NEUTRON DEGENERACY is the time from super novae to the moment of GRAVITATIONAL COLLAPSE which is days, weeks, months & years......cont'd

Benni
2.2 / 5 (10) Apr 05, 2018
cont'd........so if free neutrons have a lifespan of only 15 minutes & based on the time a star goes super novae to when gravitational collapse is speculated to occur, how is it possible a NEUTRON STAR can ever form? Simple answer: It can't.

There is no OBSERVATIONAL EVIDENCE that a hypothetical condition labeled NEUTRON DEGENERACY exists. It can't exist for the simple reason neutrons do not have a radio-active half life, and if you are not well educated in nuclear physics, as I am, you will NEVER understand why ND cannot exist in the real universe, you will be forever lost in Schneibo's fantasyland of funny farm pseudo-science.
theredpill
1 / 5 (2) Apr 05, 2018
"Momentum and orbital mechanics. And it's not clear they're stopped; they may just be slowed down. And what holds them captive is gravity. Just like the stars orbiting the SMBH."

@DaShneib - This makes absolutely no sense. An object has it's orbital path altered by a SMBH and is pulled towards it...it's momentum is in the direction of the SMBH...so there is no momentum to stop it from continuing on it's new path. You mentioned "the galaxy"...but the gravity of the SMBH already overpowered the gravity of the galaxy in order to start pulling the other BH toward it. My questions were simple, inquiring what very specific "force" stops the inward migration once it starts, you also mentioned the inverse square rule...again it makes no sense that an object is caught by a force of gravity, migrates toward it ( so it must experience an ever increasing pull as it gets closer because of that rule) and then stops. The quote didn't say "may be slowed down". It said "held captive".
theredpill
1.8 / 5 (5) Apr 05, 2018
@DaSchneib...don't bother responding. As I read this comment section it's clear that although you know basics, I am asking questions "beyond" the basics which require a response from someone who actually works in this field because "orbital mechanics" isn't the answer to a question about a specific mechanism responsible for a stated event, and I don't want to involve myself in the kind of exchange you have going here with the poster "Benni". It's clear this isn't the forum to question vagueness regarding statements or point out where something may be lacking a coherent series of events in order to arrive at a conclusion. Actually, reading this comment section it's clear everyone is very polarised in their views and has a problem with anyone who sees things from a different perspective or questions the status quo. Bye
vlaaing peerd
5 / 5 (3) Apr 05, 2018
@Da Schneib,

Though I appreciate your efforts in refuting crackpottery, I strongly recommend fighting ignorance with ignorance and press that "ignore user" button.

Worked for me and also you are entitled to enjoy the bliss of ignorance once in a while.
jonesdave
3.4 / 5 (13) Apr 05, 2018
There is no OBSERVATIONAL EVIDENCE that a hypothetical condition labeled NEUTRON DEGENERACY exists.


Yes there is, idiot. They are called neutron stars. We just detected the gravitational waves from the merger of two of them. Try to keep up, dumbo.
jonesdave
3.3 / 5 (12) Apr 05, 2018
It's clear this isn't the forum to question vagueness regarding statements or point out where something may be lacking a coherent series of events in order to arrive at a conclusion.


Then might I suggest the forum attached to this website - Physics Forums. Or Cosmoquest forums, or International Skeptics. You will find there are plenty of people with the relevant knowledge, and they aren't limited to 1000 characters when explaining it.
Benni
2.5 / 5 (11) Apr 05, 2018
@Da Schneib,

Though I appreciate your efforts in refuting crackpottery, I strongly recommend fighting ignorance with ignorance and press that "ignore user" button.

Worked for me and also you are entitled to enjoy the bliss of ignorance once in a while.


Oh please, don't do this to Schneibo......we need the entertainment value his meanderings on the plantations of funny farm pseudo-science provides us with, same with jonesy. We need the bitter clingers to 19th century cosmology here so I can have vast quantities of fun.
jonesdave
3.3 / 5 (12) Apr 05, 2018
^^^^^^^^^And this is the only person who doesn't realise that he's making a complete dick of himself! Typical of Dunning-Kruger sufferers, unfortunately.
Benni
2.2 / 5 (10) Apr 05, 2018
...again it makes no sense that an object is caught by a force of gravity, migrates toward it ( so it must experience an ever increasing pull as it gets closer because of that rule) and then stops. The quote didn't say "may be slowed down". It said "held captive".


When Schneibo talks about stuff like this, you need to understand the viewpoint he's coming from, 19th century cosmology.

He believes there is a CONSTANT MASS that is massive enough that it can generate a gravity field so intense that it can make an electro-magnetic subject to the Laws of Physics for Kinetic Energy, He along with jonesy have even put those calculations in their Comments here in the past. Their math is derived from 1/2mv² from which Escape Velocity calculations are made, a concept that comes directly from 19th century cosmology that was used in those times when it was believed that the speed of light can change based upon the strength of the gravity field it is moving through.

RNP
3.5 / 5 (11) Apr 05, 2018
@Benni
Every neutron that comes into existence in the free state will within 15 minutes decay into a proton, an electron, and a neutrino


No. The AVERAGE life-time of a free neutron is 881.5 seconds, i.e. about 15 mins; (the half-life is 661 seconds). Clearly then, not ALL free neutrons decay in 15 minutes, some take a lot longer.
antialias_physorg
4.2 / 5 (10) Apr 05, 2018
What stops them from continuing into the event horizon and holds them captive?

There's a number of things that could stop their fall.

1) They could simply go into orbit. (OK, in this specific case they still emit gravitational waves like anything that is in orbit about anything else, which will eventually deteriorate that orbit...but depending on how far out the orbit is this can be a veeeeeery drawn out process)
2) If two masses are drawn towards a black hole they can come so close to one another so that one kicks out the other (i.e. it is perfectly possible that one gets accelerated towards the black hole while the other gets accelerated away with enough speed to reach escape velocity)
3) In the case of a rotating/charged black hole the magnetic fields close in are rather intense. We already see how jets of ionized particles can escape from very close approaches to a black hole. There's no reason why a small/charged black hole could not do the same.
antialias_physorg
4.2 / 5 (10) Apr 05, 2018
No. The AVERAGE life-time of a free neutron is 881.5 seconds, i.e. about 15 mins; (the half-life is 661 seconds). Clearly then, not ALL free neutrons decay in 15 minutes, some take a lot longer.

(Shhh...don't confuse him with concepts like "half-life". He still thinks that's a computer game.)
Da Schneib
4.2 / 5 (5) Apr 05, 2018
Food for thought: the laws of orbital mechanics (with a tip o' the hat to Larry Niven):

In takes you east
East takes you out
Out takes you west
West takes you in

As you can see, the way that an orbit is affected by various motions is not intuitive. This is why it's necessary to understand orbital mechanics and not make the easy assumptions about how things work. When you are dealing with a force and an object moving at right angles to that force in three dimensions, things become complicated quite quickly. This is why things like cross products and vector addition were invented.
eachus
3.7 / 5 (3) Apr 05, 2018
What stops them from continuing into the event horizon and holds them captive?


Nothing. What do we see if a a object falls into a black hole? The light from any such object that we see is exponentially time shifted. (Same for the gravity for that matter but lots of luck separating even the gravity of a stellar mass black hole from that of the SMBH.) As an object approaches the event horizon, observers at a safe distance (us) see the object slow down to a crawl. So in theory we can still see every stellar mass black hole that ever fell into Sag A*. In practice the light is smeared out over time so the light we see from a black hole that fell in billions of years ago would be faint.

Oops! Hadn't thought far enough back. If multiple black holes fell together to form Sag A*, the light from all but the last big black hole would be swallowed as the event horizon around the central BH grew. Anyway don't expect to see events a billion years ago--or more.
Da Schneib
3.7 / 5 (3) Apr 05, 2018
Black holes are just gravity sources, like any gravity source, until you get really close (millions of kilometers, not light years- and that's only for a SMBH, for an ordinary stellar mass black hole it's more like thousands of miles). Remembering that any black holes that are in the galactic center either migrated there from the rest of the galaxy, and share its motion, or were created there from stars that were already orbiting. In either case, the small black holes will have transverse momentum and therefore will orbit (or continue to orbit) the SMBH.

Remembering that in takes you east, it's easy to see that if the gravity of the SMBH pulls you closer, your orbit speeds up. This is the explanation both for the orbits of stars and stellar mass BHs and why they don't just "fall into" the SMBH, and for accretion disks and their very high temperatures.
[contd]
Da Schneib
4 / 5 (4) Apr 05, 2018
[contd]
When we see pictures of the galactic center, it's easy to forget that we're looking at an area tens or hundreds of light years across. While the gravity of the SMBH is indeed stronger than that of individual stars or stellar mass black holes, it still isn't strong enough to pluck them out of their orbits. The inverse square law of gravity and the laws of orbital mechanics are enough to guarantee this.
dnatwork
2.8 / 5 (5) Apr 05, 2018
Wow. One guy is asking for evidence. The other group of guys is calling names. The newcomer needed only one message from Schneib to immediately conclude that the first guy is completely on the wrong, and less than a day to claim to have forgotten "more than you knew in your whole miserable little life." Then the newcomer writes in the same style as Schneib. And he begs off actually knowing higher level math, so don't bother to ask him.

I smell sock puppet.

At the very least, the level of ad hominem attacks reflects extremely poorly on one side here. If your evidence and arguments are strong, stand on them. If you resort to ad hominem attacks instead, you demonstrate that one or both are weak.
dfjohnsonphd
4.4 / 5 (7) Apr 05, 2018
Welcome to the thread, @dnatwork. Or is that the Monkey House? Vonnegut would be proud of us all! Sock puppet is right.

ad hominem attacks are acceptable as long as they provide humor and are limited. At least one of them deserves it for excessive blather. And besides, what good is science without a little levity thrown in? That clown claimed to be a nuclear engineer and did not even know about free neutron decay. Come on, you gotta slam somebody like that.

Da Schneib, did you get that link to neutron decay. Did not notice a response.

And whoever said that mathematics does not provide empirical evidence earns the top prize in reality-based science. Reproducible OBSERVATIONS by experts in a subject are the only source of empirical evidence. Mathematical constructs can provide clues, and even maybe solutions, but alone cannot prove a bloody thing except totaling your food buys at the store.

eachus
4.4 / 5 (7) Apr 05, 2018
To begin with, you never knew a free neutron is stable for ONLY 15 minutes until I pointed it out. Then I pointed out that gravitational collapse in a SN is a process of days, months & years. So let's just see how your name calling bio-chemist cohort manages neutron decay in the formation of neutron stars if you think he's so damn smart about nuclear physics.


The lifetime of a neutron under (room temperature) conditions has nothing to do with what is going on in that plasma. Electrons and protons are occasionally joining up (weak force), but more important is that you have the R process of nucleosynthesis going on. Heavy elements are being formed when the lifetime of the components is longer than the time to the next (non-elastic) collision. In the meantime lots of neutrons are boiling off either superheavy elements or fission products. So the effective neutron lifetime is an eternity compared to lifetime before being absorbed by a nucleus (or emitted by one).
Da Schneib
4 / 5 (4) Apr 05, 2018
@dfj, thanks for pointing it out; I was just getting up and missed the link. I looked last night but didn't find anything; you're pretty good at research, I guess!
jonesdave
3 / 5 (8) Apr 05, 2018
The lifetime of a neutron under (room temperature) conditions has nothing to do with what is going on in that plasma.


Yes, I think Benni may be unaware of the Pauli Exclusion Principle.

dfjohnsonphd
4 / 5 (4) Apr 05, 2018
You guys are so bright, how would a theoretical photon sphere behave in an hyper-intense frame-dragging environment? Would it escape, remain in orbit, or eventually collapse from altered space-time effects.

Perhaps the math freaks will tell us that such spheres cannot form around spinning black holes.

Theoretically of course......this question could constitute blather. Time will tell.
antialias_physorg
3.9 / 5 (7) Apr 05, 2018
how would a theoretical photon sphere behave in an hyper-intense frame-dragging environment? Would it escape, remain in orbit, or eventually collapse from altered space-time effects.

If any matter (or even energy from the CMBR that currently far outweighs Hawking radiation) falls in then any existing photon sphere would move closer to the black hole. but - and this is just a gut feeling - any, even tiny, mass that gets close to the black hole puts a bump into its event horizon/photon sphere. My gut feeling is that the conditions for such a sphere are supremely unstable.

Following case: A planet size mass starts fallling towards the photon sphere
then the gravity at the photon sphere at a point straight between the BH and the planet is that of the black hole in one direction minus that of the planet in the other direction, so any photon in that in-between region will be able to escape. With photons wizzing around the BH like crazy almost all will immediately fly off.
Da Schneib
4 / 5 (4) Apr 05, 2018
The photon sphere exists all around the black hole at the event horizon. Frame dragging therefore would cause the photons going in the direction of the BH's spin to get around the sphere faster (according to an outside observer) than photons going against the spin. A hypothetical microscopic observer at the event horizon, of course, being subject to the frame dragging themselves, perceive the direction with the spin to be shorter than the direction against the spin, and the speed of light to be constant.

This turns out to be a pretty interesting question, actually. You appear, @dfj, to have found an edge case where the speed of light is not constant according to all observers. I'm going to have to think a while to see if the above analysis has flaws in it.
Benni
2.2 / 5 (10) Apr 05, 2018
To begin with, you never knew a free neutron is stable for ONLY 15 minutes until I pointed it out. Then I pointed out that gravitational collapse in a SN is a process of days, months & years. So let's just see how your name calling bio-chemist cohort manages neutron decay in the formation of neutron stars if you think he's so damn smart about nuclear physics.


The lifetime of a neutron under (room temperature) conditions has nothing to do with what is going on in that plasma.
.......you don't know any of this for a fact. You probably also don't know that the hottest place in the Universe is right here on planet Earth, the Large Hadron Collider. An experiment at the LHC has created a quark-gluon plasma with a record-smashing temperature of 5.5 TRILLION degrees Celsius......https://www.seeke...82.html, yet no reports that such plasmas & temperatures has any effect on the 15 minute lifespan of a neutron.
jonesdave
3 / 5 (8) Apr 05, 2018
^^^^^What is pressure, and why would it be relevant to degeneracy pressure, and not to LHC experiments?
theredpill
5 / 5 (1) Apr 05, 2018
The quote that raised my initial questions: "Additionally, black holes from outside the halo are believed to fall under the influence of the SMBH as they lose their energy, causing them to be pulled into the vicinity of the SMBH, where they are held captive by its force."

Da Schneibs final statement to address my post:
While the gravity of the SMBH is indeed stronger than that of individual stars or stellar mass black holes, it still isn't strong enough to pluck them out of their orbits. The inverse square law of gravity and the laws of orbital mechanics are enough to guarantee this.

Sir, this is why I had a problem with the statement in the first place. The statement changes how things work without explaining how. That's all.
Da Schneib
3.7 / 5 (6) Apr 05, 2018
Strikes me I should explain my answer above. Remember that frame dragging isn't an effect imposed on objects within space; it is an effect on spacetime itself, and therefore any object in spacetime (inluding photons) is forced to move as the shape of spacetime (as affected by frame dragging) dictates. A laser beam that strikes the photon sphere at a tangent would be trapped in the photon sphere, and would then be affected by frame dragging as I have stated above. The path of the laser beam is a geodesic, and the shape of the geodesic is dictated by the gravity of the BH and by frame dragging.

I've thought about this and can't see a flaw in the reasoning. Is there a relativist in the house to check my work?
dfjohnsonphd
4 / 5 (4) Apr 05, 2018
@Da Schneib, I stumbled across photon sphere when looking at ergosphere in wiki:

https://en.wikipe...gosphere

This link has a nifty "mini-video" showing what happens to an object attempting a retrograde pass near a spinning BH. Too close and it cannot pass, and is "forced" by the intense warp in space-time to reverse course and begin orbiting in the direction of spin. One of the more remarkable theories about black holes that might actually be observable. Such objects might be visible by some telescopic means (or not).

One imagines that this would even happen to photons which get too close as well.
Benni
2.3 / 5 (9) Apr 05, 2018
^^^^^What is pressure, and why would it be relevant to degeneracy pressure, and not to LHC experiments?

......or "pressure", just google it, I'm not in the mood to spend time with someone who can't remember if he took Differential Equations in his high school algebra class or if it was college algebra class.
Benni
2.2 / 5 (10) Apr 05, 2018
The photon sphere exists all around the black hole at the event horizon


Then show us evidence of the photon sphere in the 7th or 10th pictures from the top of the page of Sgr A* at: http://ircamera.a...ter.htm.

One of the more remarkable theories about black holes that might actually be observable. Such objects might be visible by some telescopic means (or not).


So where then is the 3-4 million solar mass BH at Sgr A* in the above link? That's a telescopic link in case you haven't noticed, yes, actual pics taken by a real telescope of the exact center of the galaxy at the position of Sgr A* where, odd to you but not myself, there is zero observational evidence of a BH.
jonesdave
3.3 / 5 (7) Apr 05, 2018
odd to you but not myself, there is zero observational evidence of a BH.


BS, as usual. Keep lying, it's getting you nowhere.
jonesdave
3.4 / 5 (10) Apr 05, 2018
^^^^^What is pressure, and why would it be relevant to degeneracy pressure, and not to LHC experiments?

......or "pressure", just google it, I'm not in the mood to spend time with someone who can't remember if he took Differential Equations in his high school algebra class or if it was college algebra class.


Because you are an uneducated idiot. What the hell has the LHC got to do with degeneracy pressure? Zilch. So why bring it up? Because you are a scientifically illiterate idiot. You are so out of your depth that it's not funny. Go away, and learn some first grade science, before you try to tackle anything more difficult.
What is the Pauli Exclusion Principle? Go away, and learn about it, instead of polluting this board with your juvenile misunderstandings of everything scientific.
Spacebaby2001
3 / 5 (4) Apr 05, 2018
^^^^^What is pressure, and why would it be relevant to degeneracy pressure, and not to LHC experiments?


I'm no scientist so just throwing this out there, but is it because pressures in the LHC collisions are unimaginably less than those in a collapsing star despite the temperature being greater?
dfjohnsonphd
4.4 / 5 (7) Apr 05, 2018
Beeni, you would be well advised to register under another name and start posting things more appropriate to your knowledge base. Although limited, it would not expose you to such ridicule.

A photon sphere is purely theoretical. An ergoshere has a lot more going for it as it is more intuitive. But I digress.

You didn't even know that a free neutron decays for crying out loud, but claimed to be a nuclear engineer? There is really no point in debating your illogics since you will come back with an endless stream of denials of clearly established facts. Jeeez.

I am waiting for your attack, but it is likely to get frame-dragged by that SMBH in your skull.

Don't expect a reply. We would all appreciate it if you just disappeared....

Happy Trails.
Benni
1.6 / 5 (7) Apr 05, 2018
One imagines that this would even happen to photons which get too close as well.
Why? Invocation of 19th Century TUG BH Math? Odd how much you write just like your husband.

Hey, Schneibo, it looks like your wife dfjohnsonphd, writes nothing but almost mirror images of what you write. That description you gave us of her above, a similarly described bio-chemist as is dfjohnsonphd. We'll keep tabs on her & see how long she keeps posting all this fluffy stuff.

Let's see, what her name: D.F. Johnson, phd degree in bio-chemistry......ok, do some checking.
jonesdave
3.2 / 5 (9) Apr 05, 2018
^^^^^What is pressure, and why would it be relevant to degeneracy pressure, and not to LHC experiments?


I'm no scientist so just throwing this out there, but is it because pressures in the LHC collisions are unimaginably less than those in a collapsing star despite the temperature being greater?


Corrrrrect! You win the teddy bear! :) And of a bloody sight shorter duration, too. According to Benni, degeneracy can't happen, and therefore the observations in lab procedures must be lies, and observations of white dwarves and neutron stars must be faked! All because he mops the floors in a power plant, and therefore knows everything. Except how to work out the Schwarzschild radius. And that visible light heats matter, and..... well, you get the picture. Messrs. Dunning & Kruger would be salivating if they thought they could get their hands on this joker.
Da Schneib
4 / 5 (4) Apr 05, 2018
@dfj, I was actually already on that article, checking out whether frame dragging is responsible for the existence of the ergosphere. The answer of course is "yes."

Quite busy today so likely to be a little short; it's not you, my internet addiction isn't so bad I sacrifice things for it. ;)
granville583762
5 / 5 (3) Apr 05, 2018
108 comments and no mention of 20,000 stars between 6Lys!
"20,000 of these things in a region just six light years wide that no one has been able to find" Stars are 6Lys apart to have 20,000 blackholes, you have 20,000 stars to form the blackholes, there is not 20,000 stars inbetween 6Lys
granville583762
5 / 5 (3) Apr 05, 2018
And we wonder why no one has been able to find 20,000 stars/blackholes between 6Lys, our nearest star is 4Lys away, imagine 20,000 stars between us and our nearest star you certainly could not miss it.
Benni
1.9 / 5 (9) Apr 05, 2018
Beeni, you would be well advised to register under another name and start posting things more appropriate to your knowledge base. Although limited, it would not expose you to such ridicule.

A photon sphere is purely theoretical. An ergoshere has a lot more going for it as it is more intuitive. But I digress.

You didn't even know that a free neutron decays for crying out loud, but claimed to be a nuclear engineer? There is really no point in debating your illogics since you will come back with an endless stream of denials of clearly established facts. Jeeez.

I am waiting for your attack, but it is likely to get frame-dragged by that SMBH in your skull.

Don't expect a reply. We would all appreciate it if you just disappeared....

Happy Trails.


Mrs Schneibo, you need to return to the kitchen, then come back with a cogent thought.
dfjohnsonphd
4 / 5 (4) Apr 05, 2018
@granville583762 On stellar densities - data from wiki:

Omega Centauri "is estimated to contain approximately 10 million stars and a total mass equivalent to 4 million solar masses."

All of these are in a nearly spherical cluster with a diameter of about 100 light years. The average distance between stars is ca. 0.1 light years. But one must keep in mind that stellar density increases substantially as you approach the core. Since there appear to be stellar mergers in these ancient stars (blue giants have been observed), this could represent the highest possible density - i.e. limited by stellar mergers.

Ten million stars is 500 times the number of stars or black holes, whatever, near the center, according to this article. I am going to guess that the stellar density near the core of Omega Centauri is equivalent or greater than 20,000 stars within 6 light years of Sgr*.

Of course I could have gotten some bad data on this, so anybody with a better calculation is welcome.
yep
2 / 5 (8) Apr 06, 2018
"Basically, the infalling matter heats up due to friction. The collision of the matter produces photons but the extreme temperature - millions of degrees C - of the matter means those photons are released with a frequency we know as x-rays."

That's why the dentist puts a jet engine in your mouth to take an X-ray.
Questions are not dumb, just theories
yep
1.4 / 5 (10) Apr 06, 2018
Yes there is, idiot. They are called neutron stars. We just detected the gravitational waves from the merger of two of them. Try to keep up, dumbo.


Yes, 40 years and 1.1 billion dollars gets you a couple chirps that prove infinitely stupid ideas like neutron stars are real. Give me half that loot and I'll get you a couple squawks to go with those chirps.
Steelwolf
5 / 5 (1) Apr 06, 2018
DS, on the Light Sphere at the event horizon, how does that hold for the poles? Would the light sphere not be pulled into a torus instead, especially for the SMBHs? What kind of effect could this have effect on how the jet structure is formed when SMBH IS feeding? They have shown magnetic field being produced by infall tori as producing at least part of the magnetic field and particle flow for at least the outer sheath of the jets, but the core of the jets themselves is still in question. Could the Light Sphere, be so disturbed to the point, during feeding, that it accentuates the torus and allows energy release strictly from the polar regions at the same time it is actually accreting mass while at the same time gaining velocity to it's spin which is then lost back thru the Jet)?
granville583762
4 / 5 (4) Apr 06, 2018
Some of my stars are missing

150lys with10million stars is 0.7lys apart compared to 6lys with 20,000 stars is 0.2lys apart. I think the point was, you could not miss stars 0.2lys apart.

@granville583762 On stellar densities - data from wiki:

Omega Centauri "is estimated to contain approximately 10 million stars and a total mass equivalent to 4 million solar masses."

All of these are in a nearly spherical cluster with a diameter of about 100 light years. The average distance between stars is ca. 0.1 light years. But one must keep in mind that stellar density increases substantially as you approach the core. Since there appear to be stellar mergers in these ancient stars (blue giants have been observed), this could represent the highest possible density - i.e. limited by stellar mergers..

granville583762
4 / 5 (4) Apr 06, 2018
20,000 blackholes into 1 blackhole emitting only hawking-radiation

Well you could miss your 20,000 stars if they were blackholes that close, as this would only leave one starving blackhole having eaten all the other blackholes, as a starving blackhole only emits undetectable hawking-radiation – thanks Steven for making our blackhole undetectable.
antialias_physorg
3.7 / 5 (6) Apr 06, 2018
hanks Steven for making our blackhole undetectable.

Just because something doesn't emit any discernible radiation doesn't make it undetectable. The gravity is still there (and it is immense in the case of SMBHs)
granville583762
4 / 5 (4) Apr 06, 2018
The gravitational force does not change
The gravitational field of 20,000stars in 6lys vewed from 20lys has the same gravity as the same no of stars eaten by 1 blackhole, the remaing blackhole has no greater gravity than its original stars

hanks Steven for making our blackhole undetectable.

Just because something doesn't emit any discernible radiation doesn't make it undetectable. The gravity is still there (and it is immense in the case of SMBHs)

granville583762
4 / 5 (4) Apr 06, 2018
Remember antialias_physorg, this is Sir Isaac Newton's laws of gravity and motion. Any progress?
granville583762
4.2 / 5 (5) Apr 06, 2018
antialias_physorg:- where do you think the energy in the gravitational field emerges, all though it was said the question does lie in the quantum world, quantum divisions are the quantum world of the particle antialias_physorg is quantum division i.e. subdeviding the accelerative gravitational force antialias_physorg is the quantum particle of gravity the graviton, can you see antialias_physorg I am helping you answer the question. Answering this question antialias_physorg is not simply reading a pdf antialias_physorg!

Remember antialias_physorg, this is Sir Isaac Newton's laws of gravity and motion. Any progress?

antialias_physorg
3.9 / 5 (7) Apr 06, 2018
where do you think the energy in the gravitational field emerges, all though it was said the question does lie in the quantum world, quantum divisions are the quantum world of the particle antialias_physorg is quantum division i.e. subdeviding the accelerative gravitational force antialias_physorg is the quantum particle of gravity the graviton, can you see antialias_physorg I am helping you answer the question.

All I can see is that you probably need to learn how to structure a sentence, first.
granville583762
4 / 5 (4) Apr 06, 2018
This question requires a very long fuse, and you have to concentrate on the question, and not worry about grammar, spelling and other distractions, as this applies to the gravitational force emitted by blackholes, because it involves Sir Isaac Newton's laws of gravity and motion, so you see this cannot be brushed under carpet; as Isaac is still relevant today as he was 330 years ago. All I have just said now goes towards helping you ask questions to go towards answering the question.
where do you think the energy in the gravitational field emerges, subdeviding the accelerative gravitational force.

All I can see is that you probably need to learn how to structure a sentence, first.

Subdividing the accelerative force of gravity, as you have almost certainly discerned, is one of the questions for you to ask to go towards answering the question?
granville583762
4 / 5 (4) Apr 06, 2018
.

antialias_physorg> All I can see is that you probably need to learn how to structure a sentence, first.

I would not admit this in preference to the problem in hand.
granville583762
4 / 5 (4) Apr 06, 2018
You tacitly know the answer lies in Sir Isaac Newton's mathematics

antialias_physorg:- I am not giving up in despair, but i can see that you tacitly know the answer lies in Sir Isaac Newton's mathematics, but relativistic mathematics require the solution to the equation lies in stead in virtual particle that by their very nature of disappearing as rapidly as appearing equals a sum of zero which is exactly as Sir Isaac Newton's laws of acceleration equal a sum of zero. Even so, is not apparent, even taking into account the status quo, the resistance the relevance Sir Isaac Newton's influence has in the quantum world.
antialias_physorg
3.7 / 5 (6) Apr 06, 2018
This question requires a very long fuse, and you have to concentrate on the question, and not worry about grammar, spelling and other distractions

I don't know what language you are plugging into google translate, but it ain't working. You make less sense than a chatbot.

Here's a hint. Words have specific meanings. When you structure words into sentences you do this in order to convey meaning to someone else. If you don't bother to attempt this then you're just producing word salad. (i.e. you're just wasting your - and everyone else's - time

as Isaac is still relevant today as he was 330 years ago.

Not really. At (and shortly after) his time he was the best we had. Now we have better His laws are useful as an approximation ifor schoolchildren. But when you start to talk about the reality of things (you know: the part where you have to be really precise) his laws are just an anachronism.
Benni
2 / 5 (8) Apr 06, 2018
But when you start to talk about the reality of things (you know: the part where you have to be really precise) his laws are just an anachronism.


.....in other words, make it up as you go along when you need "laws" to fit a theory as opposed to taking the scientific approach & making the theory fit the laws of science.
dfjohnsonphd
3.7 / 5 (3) Apr 06, 2018
" I think the point was, you could not miss stars 0.2lys apart."

granville583762, My mistake on average density of Omega Centauri. The density of stars "at the core " is estimated at 0.1 lys apart, not in the whole cluster. This is still 2X closer than your concerns about "0.2lys apart". In either case, it would be a tight fit. There is no evidence to prove either estimate right or wrong.

If most of these stars, in either case, are close binaries, the crowding gets a lot lower.

jonesdave
3.2 / 5 (9) Apr 06, 2018
Yes there is, idiot. They are called neutron stars. We just detected the gravitational waves from the merger of two of them. Try to keep up, dumbo.


Yes, 40 years and 1.1 billion dollars gets you a couple chirps that prove infinitely stupid ideas like neutron stars are real. Give me half that loot and I'll get you a couple squawks to go with those chirps.


Oh dear, what sounds like another braindead EU bot. All talk, no science. Whinge, whinge, whinge. Go look at the pretty pictures of the colliding neutron star signals in EM. Tell us it really isn't there. You could read the papers, but I believe scientific comprehension is not high on the skills list of EU loons (who believe Earth used to orbit Saturn!).
Benni
1.7 / 5 (6) Apr 06, 2018
Oh dear, what sounds like another braindead EU bot. All talk, no science.
......and there is no "science behing the concept of "neuron degeneracy pressure, which is obviously the reason why you believe in such a non-existent law of physics.

Whinge, whinge, whinge. Go look at the pretty pictures of the colliding neutron star
........pictures of neutron stars do not exist, they are only 2 miles in diameter & there are no telescopes with resolution enough to resolve an image of something that small & take a picture of it.
jonesdave
3.4 / 5 (10) Apr 06, 2018
...
and there is no "science behing the concept of "neuron degeneracy pressure...


So go tell Pauli, Mr Dunning-Kruger. Perhaps there isn't in the world of floor mopping, but in the scientific world, neutron stars and white dwarves exist and are observed. Ergo, you fail.
dfjohnsonphd
3.7 / 5 (3) Apr 06, 2018
Close binary star systems.

For what it is worth, this link indicate binaries can be almost kissing cousins.

https://www.space...its.html

One observed binary has an orbital period of 2.5 hours! While they are red dwarfs, nothing precludes larger stars having very close orbits. Not this close for larger stars perhaps, but I suspect close enough. The real issue then is what their life span as close binaries would be due to mergers, and would their numbers be replenished over time by inward migration. Of course if many are black holes, the "crowding" is vastly reduced.

I would like to point out that the article for this story was published in Nature, the world's premiere scientific journal. Rest assured that some real high brows in astrophysics reviewed this closely before going to press. They would certainly know more than all of the people posting on this site.
Da Schneib
3.9 / 5 (7) Apr 06, 2018
@dfj, keep in mind that globulars, at least half of them, are some of the oldest things in the universe. It's possible that stars might cycle through their centers, but unlikely they're monotonically collecting there unless it's very, very slow.

As for densities, even 0.1 light years is very far in binary terms; it's 600 billion km, a hundred times the distance of Pluto from the Sun. While this is very much higher density than in the galactic plane except in very compact open clusters, it's still very far apart in planetary or multiple star system terms.

Just food for thought.
Benni
1.7 / 5 (6) Apr 06, 2018
So go tell Pauli......neutron stars and exist and are observed.
It is impossible to image a neutron star because they are only two miles in diameter, we don't have telescopes that can resolve an image that small

Pauli exclusion principle is the quantum mechanical principle which states that two or more identical fermions (particles with half-integer spin) cannot occupy the same quantum state within a quantum system simultaneously.

The existence of the neutron's magnetic moment indicates the neutron is not an elementary particle. For an elementary particle to have an intrinsic magnetic moment, it must have both spin and electric charge. The neutron has spin 1/2 ħ, but it has no net charge as does an electron, therefore cannot become degenerate under pressure.
dfjohnsonphd
4.2 / 5 (5) Apr 06, 2018
Quite correct DS. 0.1 light years is a tad more than a stone's throw.

Reading about Omega Centauri, it is believed to be the core of a dwarf galaxy snagged by our galaxy a long time ago and stripped of gas and younger stars. Some evidence for a central black hole of around 10^4 solar masses, but this is being contested.

Possible that all such large tight clusters are ancient galaxy cores. That would certainly explain their stellar ages. They surely are not newbies. Still struggling with the metallicity issue in that paper you gave me. Have read contradictory reports on metallicity and stellar age. Perhaps stellar mergers could be confounding the issue.
jonesdave
3.4 / 5 (10) Apr 06, 2018
The neutron has spin 1/2 ħ, but it has no net charge as does an electron, therefore cannot become degenerate under pressure.


And here goes lying Benni again! Why didn't you copy/ paste the rest of that Wiki? You know, the bit that says:

Additionally, baryons such as protons and neutrons (subatomic particles composed from three quarks) and some atoms (such as helium-3) are fermions, and are therefore described by the Pauli exclusion principle as well.


and also.....

In 1995 Elliott Lieb and coworkers showed that the Pauli principle still leads to stability in intense magnetic fields such as in neutron stars, although at a much higher density than in ordinary matter.


Lieb paper: https://arxiv.org.../9506047

Quit the lying Benni; being scientifically illiterate is bad enough.

jonesdave
3.4 / 5 (10) Apr 06, 2018
It is impossible to image a neutron star because they are only two miles in diameter, we don't have telescopes that can resolve an image that small


And we can't image an electron, but we infer their presence. We often cannot resolve the individual stars that give rise to distant supernovae, but we can infer their presence. So, we predict the existence of neutron stars, we predict how they should behave, and what therir signatures are, and what will happen if they merge. And we get it all right when we look at them.

https://wtop.com/...created/

....... + numerous papers.

alexander2468
3.4 / 5 (5) Apr 06, 2018
20k stars in 6lys is neutron star densities
Close packed stars, the density of 20,000stars in 6lys diameter is 1.7x10+17kg /m3 Neutron Stars average is 4.8x10+17 kg/m3. The gravity between stars will collapse all 20k stars to a blackhole of 120,000km diameter.

Theres's one word - to close
antialias_physorg
3.4 / 5 (5) Apr 06, 2018
As for densities, even 0.1 light years is very far in binary terms; it's 600 billion km, a hundred times the distance of Pluto from the Sun. While this is very much higher density than in the galactic plane except in very compact open clusters, it's still very far apart in planetary or multiple star system terms.

Rroughly 75% of stars are red dwarfs and relatively cool (ony 2000-4000K). At a distance of 0.1 light years you might even miss them. Our closest neighbor, Proxima Centauri, is a red dwarf - not visible to the naked eye. Several observation missions in the past decades have scanned the night sky to check if our *own* solar system is a binary (yep - we still don't know for certain, though it's loking mor likely "no" than "yes"). That should give an indication how little one would notice a red (or even brown) dwarf star.

One should not confuse 'star' with 'our sun'. Our sun is quite a bit bigger/brighter than the average star.
granville583762
5 / 5 (3) Apr 06, 2018
Looks like these stars will be a blackhole lunch snack, before the stars see their solar light of day.

" I think the point was, you could not miss stars 0.2lys apart."

granville583762, My mistake on average density of Omega Centauri. The density of stars "at the core " is estimated at 0.1 lys apart, not in the whole cluster. This is still 2X closer than your concerns about "0.2lys apart". In either case, it would be a tight fit. There is no evidence to prove either estimate right or wrong.

If most of these stars, in either case, are close binaries, the crowding gets a lot lower.


antialias_physorg
3.3 / 5 (7) Apr 06, 2018
20k stars in 6lys is neutron star densities

I get adifferent numbers.

Solar mass: 2*10^30kg
Average stellar mass is 0.36 solar masses = 0.72*10^30kg

A sphere 6 ly in radius has a volume of roughly 3.6*10^39km^3

So I get the average density in such a region of space to be 0.2*10^-9kg/km^3
That's 0.2 nanograms of matter per cubic kilometer.

I think that's a tiiiiny bit less than 'neutron star densities'

Maybe you can show your math so we can compare?
antialias_physorg
3.3 / 5 (7) Apr 06, 2018
Oops..missed the factor 20k for the amount of stars in that volume...my bad

So the average density is 4*10^-6 kg/km^3
(4 micrograms of matter per cubic kilometer...still a long ways off to neutron star densities...about 31 orders of magnitude)
alexander2468
4 / 5 (4) Apr 06, 2018
8.4x10+16kg/m3 or 3.02x10+16kg/m3 there's one word, still to close

D (9.461x10+15) 4/3 . pi 3.1416=pi, 9.461x10+15= one light year, a 6Lyr volume=2.377814208x10+17m3
20,000 stellar mass stars at 2x10+30kg= 2x10+34kg. I always take 2x10+30 as a safe figure
2x10+34 / 2.38x10+17 = 8.4x10+16kg/m3 for 1 solar mass
for 0.36 solar mass = 3.02x10+16 trying harder,on a second attempt 10+17kg/m3 drops to 10+16 kg/m3 still to close, the mass still coalesces in a blackhole.
alexander2468
4 / 5 (4) Apr 06, 2018
there's one word, still to close

trying harder,on a second attempt only makes marginal difference
antialias_physorg
4.4 / 5 (7) Apr 06, 2018
D (9.461x10+15) 4/3 . pi 3.1416=pi, 9.461x10+15= one light year, a 6Lyr volume=2.377814208x10+17m3

I think you're missing a couple orders of magnitude on your volume calculations.
The formula for a volume is 4/3 * pi * radius TO THE THIRD POWER
antialias_physorg
4.3 / 5 (6) Apr 06, 2018
Just for giggels I did the inverse calculation to figure out how small a volume you would have to scrunch the mass of 20000 stars into to actually get to neutron star densities:
It's sphere with just 325km radius
dfjohnsonphd
5 / 5 (3) Apr 06, 2018
Actually we have imaged several neutron stars.

They are known as "optical pulsars", which if you understand English, pretty much says it all.

Check it out for any naysayers:

https://en.wikipe...l_pulsar

Don't blame the messenger if you don't like being presented with established facts.

dfjohnsonphd
5 / 5 (5) Apr 06, 2018
@antialias_physorg, what are a couple orders of magnitude in the grand scheme of things?

Wait, that is 100X or so.

Just pulled a Rosanne Rosanadana.

Never mind........ :o)

691Boat
5 / 5 (4) Apr 06, 2018
I asked Wolframalpha regarding the volume, and Alexander is definitely way off. Such amazing tools are out there to prevent one from making silly mistakes. Take advantage of them!
~9.6x10^40 km^3
http://www.wolfra...re+in+km
alexander2468
3.7 / 5 (3) Apr 06, 2018
maths goes to pot commenting 6lys cubed would reduce density. Still to close, their gravity+ darkmatter is a blackhole, 325km radius+20k stars equals a blackhole. their must be repulsion.
Just for giggels I did the inverse calculation to figure out how small a volume you would have to scrunch the mass of 20000 stars into to actually get to neutron star densities:
It's sphere with just 325km radius

alexander2468
3.7 / 5 (3) Apr 06, 2018
using calc98 what do you expect, easily corrected r cubed, still to close and+darkmatter or doesn't it exist

I asked Wolframalpha regarding the volume, and Alexander is definitely way off. Such amazing tools are out there to prevent one from making silly mistakes. Take advantage of them!
~9.6x10^40 km^3
http://www.wolfra...re+in+km

alexander2468
3.7 / 5 (3) Apr 06, 2018
bookmarked.wolfram, galaxies have darkmatter for rotation, is Sagittarius-A darkmatter free with stars 0.2 and less Ltys apart the Oort cloud is in solar orbit orbiting 50,000 and 200,000 AU (0.8 and 3.2 ly)
691Boat
5 / 5 (4) Apr 06, 2018
My Mathematica calculation using 20,000 masses with average mass of 0.5 solar masses in a volume of space with a 3LY radius equates to ~2*10^-7 kg*km^-3. That's pretty sparse!!
antialias_physorg
4.3 / 5 (6) Apr 06, 2018
I asked Wolframalpha regarding the volume, and Alexander is definitely way off. Such amazing tools are out there to prevent one from making silly mistakes. Take advantage of them!
~9.6x10^40 km^3
http://www.wolfra...re+in+km

Dang it.."6 light years wide"...I used a 6 light years radius not a 3 ly radius. Shouldn't do math at midnight. Thx for the heads-up. That ups the density by a factor of 8 (still in the microgramn per cubic kilometer range, tho)

325km radius+20k stars equals a blackhole.

Of course.Such a mass in that kind of volume woud immeditely collapse to a black hole. Just saying that to get to neutron star densities you have to pack 20k stars very, very, VERY much closer than "within a 6ly diameter sphere".
antialias_physorg
4.4 / 5 (7) Apr 06, 2018
Checked around for densest sphere packing and the average radius of an average red dwarf (the latter is difficult to find but a bit of judicious averaging over several sources gives me 200k km radius)

If you want to pack 20000 red dwarfs without making the mass more dense (i.e. just lay them out faces touching in a hexagonal packing formation) then that would fit within a larger sphere with roughly 6 million km radius. For comparions the average orbital radius of Mercury is about 10 times as large.

Takeaway message: Space is big. Really big. Stars are tiiiiiny compared to how big space is.
granville583762
3.4 / 5 (5) Apr 06, 2018
These mathematical spherical cubism mistakes have highlighted the absence of darkmatter

I've noticed no one has questioned stellar separation of 0.2 light years, you can simply cube 6 divide by 20,000 inverse cube is 0.22 light years, the spherical cubed quibbling is diversionary tactic as the spherical figures are all over the place; were they deliberate to inspire quibbling? As has been pointed, out what is holding the stars apart between 0.1 to 0.2 light years apart as darkmatter strange as it seems darkmatter has been excluded! Has darkmatter been quietly excluded because it will only increase the force pulling the stars together?
granville583762
5 / 5 (3) Apr 06, 2018
Disregarding every ones cubist's mistakes, a lot of interesting properties are derived from these stellar exercises.
Checked around for densest sphere packing and the average radius of an average red dwarf (the latter is difficult to find but a bit of judicious averaging over several sources gives me 200k km radius)

If you want to pack 20000 red dwarfs without making the mass more dense (i.e. just lay them out faces touching in a hexagonal packing formation) then that would fit within a larger sphere with roughly 6 million km radius. For comparions the average orbital radius of Mercury is about 10 times as large.

Takeaway message: Space is big. Really big. Stars are tiiiiiny compared to how big space is.

the witching hour is where the best ideas come
antialias_physorg
4.4 / 5 (7) Apr 06, 2018
darkmatter been quietly excluded because it will only increase the force pulling the stars together?

DM and regular matter are not equally distributed.

As has been pointed, out what is holding the stars apart between 0.1 to 0.2 light years

Same thing that keeps the Earth from diving straight into the sun (orbital mechanics)
691Boat
5 / 5 (4) Apr 06, 2018
@granville:
I think you are really failing to grasp the distances being discussed. 0.2ly is an incredible distance. I found a worksheet from NASA to help you understand astronomical distances a bit better: https://www.nasa....Act1.pdf
Is dark matter the reason the Earth hasn't crashed in to the sun? Does dark matter prevent the moon from crashing in to the Earth? For crying out loud, the moon and Earth are only separated by 4.26x10^-8 ly!!!!
Da Schneib
4.2 / 5 (5) Apr 06, 2018
Takeaway message: Space is big. Really big. Stars are tiiiiiny compared to how big space is.
It's surprising but most people just don't seem to get this.

At public viewing events, I usually give a grand tour of the Solar System on a football field. On that scale the Sun is a beach ball on the goal line, Earth is a pea on the 5 yard line, Jupiter is an orange on the 35 yard line, and Pluto is a seed at the other goal line. I then tell them that on that scale Alpha Centauri is in New York (I live in California). This is a start at getting it across.

Space is really, really, really big. Every star you see in the sky is either unusually close (only a few of them-- a handful really) or unusually bright (most of them-- a few thousand). You can see 3000 stars in one hemisphere of the sky. If Earth circled a star in a globular cluster you could probably see millions of stars in the sky.
granville583762
5 / 5 (3) Apr 06, 2018
It's not the distance of planetary or stellar separation, it's their orbital velocity, stellar binary orbits reach over 6 light years separation, it's what keeps galactic stars apart, not darkmatter,
@granville:
I think you are really failing to grasp the distances being discussed. 0.2ly is an incredible distance. I found a worksheet from NASA to help you understand astronomical distances a bit better: https://www.nasa....Act1.pdf
Is dark matter the reason the Earth hasn't crashed in to the sun? Does dark matter prevent the moon from crashing in to the Earth? For crying out loud, the moon and Earth are only separated by 4.26x10^-8 ly!!!!

The Oort cloud is a lot further than one light year and 0.2 light years to Andromeda is miniscule
jonesdave
3.3 / 5 (7) Apr 06, 2018
Space is big. Really big.


And no one can hear you scream.
Da Schneib
5 / 5 (4) Apr 06, 2018
@gran, on my football field scale the Oort cloud is in Nevada more or less.
granville583762
5 / 5 (3) Apr 06, 2018
The stars binary orbit each other with one rotation of Sagittarius A, the same as one rotation of the milkyway, darkmatter plays no part, effectively as though it does not exist.
darkmatter been quietly excluded because it will only increase the force pulling the stars together?


DM and regular matter are not equally distributed.

As has been pointed, out what is holding the stars apart between 0.1 to 0.2 light years

Same thing that keeps the Earth from diving straight into the sun (orbital mechanics)

jonesdave
3 / 5 (6) Apr 06, 2018
@gran, on my football field scale the Oort cloud is in Nevada more or less.


Aha, and I guess the comets (minus Bill Haley) are playing Las Vegas?
antialias_physorg
4.3 / 5 (6) Apr 06, 2018
Takeaway message: Space is big. Really big. Stars are tiiiiiny compared to how big space is.

It's surprising but most people just don't seem to get this.

Most people don't really care about anything above head height. Sizes beyond a few meters are also not on most people's radars (heck, most don't have a good grasp of the area of the city they live in, so how can one expect them to get to grips with stuff like cosmic volumes?). Thinking in orders of magnitude is also not something that our brains are particularly well suited to (ask anyone to imagine "10 orders of magnitued"..no one can). It just wasn't useful in our evolutionary history to acquire that skill.

That most any educational material (and of course movies/TV shows) displays planets and stars disproportionally large and prominent as opposed to the vastness of space doesn't help one bit, either.
antialias_physorg
4.5 / 5 (8) Apr 06, 2018
I used to live in Bonn, and they have an 'planet path'-installation next to the bike lane that runs along the Rhine river (at the usual scale of 1 to 1 billion).
The first point is the sun (a sphere with 1.5 meter diameter) and then the planets to scale and in the appropriate distance...you pass the Earth within 150 meters (the moon is a whole 40cm next to it)...Pluto (which was still a planet when they set this up) is about 6km out.
I was riding along this every morning to work.
It's a neat way to get to grips with the distances and sizes.
jonesdave
3.5 / 5 (8) Apr 06, 2018
OK, here are some factoids I just calculated.
1 ly = ~ 1 x 10^13 km.
Therefore, 0.2 ly = ~ 2 x 10^12 km.
1 AU = 1.5 x 10^8 km.
So, 0.2 ly = ~ 13 000 AU.
A wide binary pair can orbit at ~ 1000 AU. On the other hand Alpha Centauri A & B orbit at ~ 11 AU. Proxima is 0.2 ly from those two, and some people question whether it is actually part of that system.

To reiterate - space is bloody big.
Da Schneib
5 / 5 (5) Apr 06, 2018
Just did some searching.

Found that in November of 2013, an international team of astrophysicists discovered radio signatures of black holes sucking in gas in the cores of globulars.

Found that in about May of 2014, a group of astrophysicists comprised of astrophysicists from the University of Texas at Austin collaborating with astrophysicists from the Max Planck Institute in Germany found that instead of the chaotic star orbits they expected near the centers of globulars, they saw many stars orbiting a common center.

The current state of follow-up has confirmed these findings, and just recently for the first time a star has been discovered orbiting a black hole near the center of a globular. The links will be in the next post.
Da Schneib
5 / 5 (5) Apr 06, 2018
https://phys.org/...tar.html
http://www.astron...at-heart
https://www.space...ter.html
http://www.astron...-cluster

So at this point, current data seem to indicate that there are black holes in the centers of globulars. It's not clear what the full dynamics of the situation are, but that appears to be the story. Ten years ago no one knew. There's a lot happening right now in this area of research, by all appearances.
dfjohnsonphd
5 / 5 (2) Apr 06, 2018
Yeah, space is very big, but what percentage is occupied by significant matter. Galaxy clusters in extended filaments vs. the vast voids nearly empty of anything. I would guess the voids amount to 90% of all that space (including intergalactic space, which is largely voids). I cannot find a good guesstimate with a limited search and figure one of you eggheads might have a close approximation.

To me, space is empty, unless its in my garage. And that has a mass density you don't even want to hear about.
Da Schneib
5 / 5 (4) Apr 06, 2018
You've got the right idea, @dfj, but I don't think it's as high as 90%, more like 80% or so. They also aren't completely empty; they contain about 20% of the visible matter in the universe according to multiple sources. It's very sparse in a void compared with intergalactic space along a filament, and far sparser compared with the interstellar space within a galaxy, but it's still there. For more details google "cosmic voids percent of the universe."

I should also mention that along a filament, there is not only quite a bit more than is in a void, but also a lot more dark matter. Astrophysicists and cosmologists think that the matter-- both dark and visible-- collected together early in the history of the universe and made stars, galaxies, and galaxy clusters, and that a lot of material was pushed out of galaxies by black hole jets into the voids. Anyway that's what most sources say now. We'll see how that holds up when we get a closer look, starting with the JWST.
dfjohnsonphd
5 / 5 (2) Apr 06, 2018
They are all primordial black holes, DS. Those clusters are ancient. PBHs are even more ancient. No data can refute this notion, so I am hanging into it for the duration, however long that is. It just feels so right. Yeah, a gut feeling, but many of mine work out.

PBHs seeded the early universe with hyperdense objects around which all that hydrogen would gather to form galaxies. The bigger the PBH, the faster it formed and older the galaxy. Our Milky Way has a puny SMBH, which is why it is still a grand spiral. Still lots of infalling hydrogen into our disc. How big are the SMBHs in large highly evolved ellipticals? Jumbo?

One of the more fascinating things I read about PBHs suggested that one born with a mass of 1 trillion Kg would only now be reaching terminal evaporation. Does anybody with a calculator know if Hawking radiation dovetails this estimate, or was I reading bad data/science?
dfjohnsonphd
5 / 5 (2) Apr 06, 2018
It is M87 I was thinking of. Massive elliptical with an enormous BH at its core. Latest estimate is ca. 7 x 10^9 solar masses. Just a tad larger than ours, eh. Now why would that be? What mechanism other than PBHs would allow for such large variations in galaxy formation and core BHs.

M87:

https://en.wikipe...ack_hole

I believe that most giant ellipticals are like this. Grand spirals were slower to evolve because they started with much smaller PBHs.

Anyone care to disprove this by empirical observations? And don't trash on me because you don't like the idea of primordial black holes.
Da Schneib
5 / 5 (2) Apr 06, 2018
Heh, @dfj, I admire your boldness, but I have to tell you that they're most likely from large stars that went supernova during the lifetimes of the globulars. Could they have started with PBHs? Maybe, and as you say it could be very difficult to find evidence for or against. Certainly we don't have the instruments to do it now or in the near future.

We've made simulations of galaxy formation and evolution that yield a universe pretty much like ours without PBHs being significant. You might find some research into that valuable.
dfjohnsonphd
5 / 5 (1) Apr 06, 2018
I see how large stars can supernova to create black holes. But you really think they are going to form biilion+ solar mass BHs at the core? That's a lot of rapid supernovas going down in a small region for each infantile galaxy.

If your simulations rely on early Type II core collapses by the billions to build so many large core BHs, how did all these massive stars form in the early universe? High density hydrogen pockets condensing to form 25-150 solar mass stars with a flurry of core collapses? Any empirical evidence for that? What is the time line of the simulation to create such enormous BHs?

Did you also run any simulations using PBHs to "yield a universe pretty much like ours", or simply reject that course because you don't like it. Not being cheeky here, just wondering about all options. Too little is known in all this to lock in one theory of galaxy formation and evolution to the exclusion of all others.
dfjohnsonphd
5 / 5 (1) Apr 07, 2018
Jeez, I just noticed you said "during the lifetimes of the globulars".

I am talking about formation of the giant galaxies. Or did you mean giant galaxies in your simulations?
Da Schneib
5 / 5 (1) Apr 07, 2018
They found an intermediate mass BH in that globular orbiting that 47 Tucanae galaxy; IIRC that's a pretty close galaxy, maybe even in the Local Group. I don't think they've gotten as far as actually finding a big BH in the core of a globular orbiting the Milky Way; I didn't see anything like that being announced, and "globular cluster black hole" seems like a pretty good search string to me. I think if they can find little black holes in globulars orbiting other galaxies, even in the Local Group, if there were big ones they'd've found them.

I'm not talking about BHs at the cores of galaxies, but at the cores of globulars. And the formation and evolution of globulars, though I don't have much to say because we don't appear to know much. I think we got our wires crossed.
Da Schneib
5 / 5 (1) Apr 07, 2018
As far as galaxy evolution, I think that's even more disorganized right now than globular cluster evolution, since galaxies are so much larger. There's been a lot of simulatin' goin' on, but not much meat. The spread of variables is too wide and too many, that all yield a universe with galaxies "pretty much like ours." Globulars are less varied, so the parameters are a bit tighter.
dfjohnsonphd
5 / 5 (1) Apr 07, 2018
DS, here is some meat for thought:

In 1937, if you asked Neils Bohr to simulate the fission of heavy atomic nuclei, he would have laughed and said "that is impossible, they cannot be fractured". All of those physicists were of the same mind. It was almost a law. They were in an echo chamber.

In 1938 Otto Hahn discovered such fission in his test tubes, and forever shattered that echo chamber and shook the world. In 1945, nuclear fission would literally shake the world at Alamogordo, Hiroshima and Nagasaki, just for starters. It has been shaken many times since.

It is recommended that people who work with highly theoretical simulations be aware that they may be thinking in a small box, having excluded alternatives which might provide the basis by which the correct mechanism(s) are deduced. It is suggested that people in such boxes might try pushing on the lid at times and see if there is anything notable "outside the box." One never knows what lurks out there......
dfjohnsonphd
5 / 5 (1) Apr 07, 2018
To close (for now) on this black topic :

Primordial BHs were first proposed by Hawking in 1971. Puns aside, I don't care to "dig up" Hawking's writings, but those simulations appear to limit their size. Since we cannot see such objects, especially in the moments after the Big Bang, all current observations suggesting they do not exist are considering them only as smaller objects, paying no attention to their potential evolution in the early stages of "creation".

Any hard data showing stellar-based BH formation elbowing out PBHs? That would satisfy my curiosity. At this "late" date, there would be no detectable signature for their early formation. If simulations are giving variable results (rarely do otherwise), other variables could slip into the picture, if properly simulated of course. Biggest problem I see is that simulations of the origin of galaxies is an exercise in futility. How can you be sure that you have the right answer? One might reasonably suggest that you cannot.
yep
1 / 5 (3) Apr 09, 2018
Biggest problem I see is that simulations of the origin of galaxies is an exercise in futility. How can you be sure that you have the right answer? One might reasonably suggest that you cannot.


That might be the the smartest thing anyone has posted on this thread.
antialias_physorg
3.7 / 5 (3) Apr 09, 2018
Any hard data showing stellar-based BH formation elbowing out PBHs?

Check the entries under "Micro-Lensing" and "Temperature anisotropies in the cosmic microwave background"
https://en.wikipe...rategies

While the situation isn't settled there are indications that PBHs don't contribute greatly (if at all) to DM. The whole thing is a bit model dependent so further research is needed. But for now it looks like they're probably not the answer.

With better gravitational observatories coming on line we should get info on this soon-ish, since if there are loads of these PBHs about to constitute a significant fraction of DM (scary thought!) then we should register a lot of mergers happening.

How can you be sure that you have the right answer?

Just look at old galaxies and check if they look the way you expect.
691Boat
5 / 5 (2) Apr 09, 2018
I used to live in Bonn, and they have an 'planet path'-installation next to the bike lane that runs along the Rhine river (at the usual scale of 1 to 1 billion).
The first point is the sun (a sphere with 1.5 meter diameter) and then the planets to scale and in the appropriate distance...you pass the Earth within 150 meters (the moon is a whole 40cm next to it)...Pluto (which was still a planet when they set this up) is about 6km out.
I was riding along this every morning to work.
It's a neat way to get to grips with the distances and sizes.

They have a similar thing in Eugene, Oregon along the bike path by the Willamette River. Really helped to appreciate the scale. http://members.ef...~jack_v/
savvys84
1 / 5 (1) Apr 11, 2018
the fact that our sun bobs up and down and moves sideways to and fro while orbiting the center of the galaxy seems to suggest that it is also orbiting some local balck hole and that local black hole carries it around the center of the galaxy

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