Dark matter and its effect on the orbit of stars

[petercl14]

TL;DR Summary

dark matter or black holes effect on star orbits

Hi all, As I understand it scientists have postulated that dark matter exists to explain the unexplained orbit of stars around the centre of our galaxy. The orbits not being as they should be by Newtonian or Einstein calculations. At the same time they postulate that there are perhaps 1000s of black holes in our milky way galaxy alone. Not just the massive black hole at the center of the milky way galaxy.

Have the scientists that believe in dark matter considered that the unexplained star orbits could in fact be due to the black holes? Have they found even one black hole other than the one at the center of the milky way galaxy? If they have then this would also confirm that there may in fact be 1000s of black holes as they also suggest. There would then be no need to bring in the idea of dark matter.

 

[phinds]

Do you seriously think none of this has been thought of by the thousands of cosmologists who have thought about this stuff over many years?

Have you done any research on this or is this just some random idea you've come up with?

 

[Ibix]

Black holes have been considered, yes. You need more than thousands of them - you need more mass in them than there is in the visible stars, so at least in the billions of them per galaxy. And with that many floating around you ought to see gravitational lensing of stars as the black holes pass in front of them fairly frequently. And we never have. So we're fairly confident that whatever dark matter is, it's not black holes.

Yes, we're aware of objects that are probably stellar-mass black holes with accretion discs, along with super massive black holes (of which we are aware of more than one, by the way). The Cygnus X1 x-ray source is probably the most famous.

 

[IS80]

No such thing as a stupid question. Just continue your quest for knowledge at your own pace @petercl14.

[Mentor Note: Post edited to remove mild insult.]

 

[Vanadium 50]

No such thing as a stupid question.

Yes there most certainly is.

"Will this be on the test?"
"I missed the last three weeks. Did we cover anything important?"
Need I go on?

 

[Vanadium 50]

Back to the post at hand.

(1) The premise that scientists are a bunch of ignorant yahoos that need the OP to point the way is...um...not supported by the facts.
(2) Most, if not all, of the OPs questions can be answered by typing them into Google. Verbatim. Now, he may still have questions, but now we can discuss them better since he's put in some effort to educate himself.
(3) Stellar-mass black holes were once stars. The Dark Matter distribution is not the same as the stellar distribution. One would need to explain how they moved from here to there.
(4) Most former stars do not become black holes. If DM were black holes, the ordinary matter would be primarily in other stellar remnants: neutron stars and white dwarfs. That is not what we see.

 

[phinds]

(1) The premise that scientists are a bunch of ignorant yahoos that need the OP to point the way is...um...not supported by the facts.
(2) Most, if not all, of the OPs questions can be answered by typing them into Google. Verbatim. Now, he may still have questions, but now we can discuss them better since he's put in some effort to educate himself.

 

[petercl14]

Black holes have been considered, yes. You need more than thousands of them - you need more mass in them than there is in the visible stars, so at least in the billions of them per galaxy. And with that many floating around you ought to see gravitational lensing of stars as the black holes pass in front of them fairly frequently. And we never have. So we're fairly confident that whatever dark matter is, it's not black holes.

Yes, we're aware of objects that are probably stellar-mass black holes with accretion discs, along with super massive black holes (of which we are aware of more than one, by the way). The Cygnus X1 x-ray source is probably the most famous.

Apparently the only effect dark matter has is it gravitational effect on real matter. It is suggested that it is like a web in intergalactic space. It is well established that large gravitational objects bend light such as the sun. It makes you wonder then how we can even see with clarity distant galaxies with this intergalactic dark matter in the way. You either couldn't see at all distant galaxies or there would just be a blur of light in the sky at night.
Scientists are now suggesting dark energy as well. When will it stop for things that can be easily explained be other means. This will be in another blog.

 

[Vanadium 50]

This will be in another blog.

I certainly hope not.

We ignorant yahoos in the sciences have actually done the calculation of what is the impact of dark matter on gravitational lensing. And you know what? It matches what we see - not what you guess.

 

[Ibix]

It is well established that large gravitational objects bend light such as the sun.

As I said in the post you quoted, this is why we know dark matter isn't black holes.

 

[phinds]

This will be in another blog.

Please don't

 

[Drakkith]

Apparently the only effect dark matter has is it gravitational effect on real matter.

And radiation.

It makes you wonder then how we can even see with clarity distant galaxies with this intergalactic dark matter in the way. You either couldn't see at all distant galaxies or there would just be a blur of light in the sky at night.

It's not 'in the way'. That implies that it impedes the transmission of light through the universe, which it doesn't. It doesn't interact with light in any way except gravitationally, which merely alters the path of the light, not block it.

Scientists are now suggesting dark energy as well. When will it stop for things that can be easily explained be other means.

If by "now suggesting" you mean "have been suggesting for nearly 30 years", yes. And no, the issues in cosmology cannot be explained by another means. That's why dark energy and dark matter are still the prime suspects. If things could be better explained without using dark energy and dark matter then cosmologists would do so.

This will be in another blog.

No one cares.