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Galaxy rotation curve

Galaxy rotation curve

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MB

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When I first read that galaxy rotation curve is nearly constant I immediately realized that is not how the accepted laws of gravity are supposed to work. If the laws of gravity cannot explain the nearly constant rotation curve then the laws of gravity must be incomplete.

Surely I could not be the only person to deduct that so I looked into it and I was right, others noticed and they have an entire field of study to attempt to modify the current laws of gravity. It is called modified Newtonian dynamics (MOND).

I also realized that dark matter alone could not explain those nearly constant rotation curves, so why are people still stuck on the idea of dark matter? You would think people would have abandoned dark matter theory soon after the nearly constant rotation curves of galaxies were discovered. It is like they didn't get informed and they are stuck in the past. Here is a website to demonstrate that people still assume galaxies have a rotation curve that the current laws of gravity predict.

Here is an excerpt from the link below:

""The basic physics of why galaxies have spirals is known, but the details remain controversial, sometimes intensely so. Spirals exist only among flattened or 'disk' galaxies. These galaxies are differentially rotating--that is, the time to complete a full rotation increases with distance from the center."

https://www.scientificamerican.com/article/what-process-creates-and/

The time to complete a full rotation increases with distance from the center only slightly according to measurement, so that appears to be outdated information that is largely contradictory.

But hold on. Just the observation of the spiral arms of a galaxy alone seems to suggest that the rotation curve of galaxies are not nearly constant. Could it be the people who measured the speed of stars rotating around galaxies got the measurement wrong?

I found out that measuring the speed of stars is a very complex task. Although the speed of stars seem fast when you look at the numbers the ratio of distance from the center of the galaxy is so great stars seem to be at a standstill to us, like measuring the speed of a snail.

Did they get the measurements wrong? That would resolve the contradiction.

Are the laws of gravity incomplete? If so, why are people still talking about dark matter? Dark matter alone cannot explain a nearly constant rotation curve with the current laws of gravity, right?

divegeester
watching in dismay

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This is not the conspiracy you are looking for…

[waves hand]

MB

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1 edit

@divegeester said
This is not the conspiracy you are looking for…

[waves hand]
Nice Jedi joke.

I think it is likely the astrophysicists who did the measurements got it wrong. All sorts of variables had to be taken into account like the speed of the sun and the speed of our planet rotating around the sun. Measurements would have to be taken 6 months apart to adjust for the difference and that is just on our side of it.

There is also the size of stars that is hard to know. Is it small or just farther away than you think? It is hard to know exactly. I once read that supernovas have a consistent size when they explode. Did they measure supernovas? I don't know.

A measurement error is the more simple explanation. Going by Occam's razor isn't that the most likely explanation?

https://en.wikipedia.org/wiki/Occam's_razor

No conspiracy here. Just a brain teaser I thought a lot about.

shavixmir
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@metal-brain said
When I first read that galaxy rotation curve is nearly constant I immediately realized that is not how the accepted laws of gravity are supposed to work. If the laws of gravity cannot explain the nearly constant rotation curve then the laws of gravity must be incomplete.

Surely I could not be the only person to deduct that so I looked into it and I was right, others n ...[text shortened]... atter alone cannot explain a nearly constant rotation curve with the current laws of gravity, right?
Uh…

No. Sorry. Not a subject I know anything about.

I would presume, however, that’s it’s a gravity thing. Moon revolves around us, we around the Sun, etc.
And doesn’t gravity distort time? And surely, if we then divide the mass by the moon’s speed, we get the G-x squared of dark matter which squared again by ABBA gives us a wee bit of T-rex?

mike69

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@metal-brain said
When I first read that galaxy rotation curve is nearly constant I immediately realized that is not how the accepted laws of gravity are supposed to work. If the laws of gravity cannot explain the nearly constant rotation curve then the laws of gravity must be incomplete.

Surely I could not be the only person to deduct that so I looked into it and I was right, others n ...[text shortened]... atter alone cannot explain a nearly constant rotation curve with the current laws of gravity, right?
Isn’t dark matter unproven, discovered or anything to be able to use it in their explanations? I’m just curious if I missed something.

AThousandYoung
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Take it to the Science forum Spanky

MB

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@mike69 said
Isn’t dark matter unproven, discovered or anything to be able to use it in their explanations? I’m just curious if I missed something.
It depends on what you mean by dark matter. If it is just matter that is dark that exists that is no problem. Black holes exist for example. If you are talking about some different kind of matter we do not know of that it is unproven I can only say that is a wild theory. Totally unproven.

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@metal-brain said
It depends on what you mean by dark matter. If it is just matter that is dark that exists that is no problem. Black holes exist for example. If you are talking about some different kind of matter we do not know of that it is unproven I can only say that is a wild theory. Totally unproven.
My knowledge is slim, this why I was asking. I watch a documentary about scientists looking deep in the ocean for it but just a theory.

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@metal-brain said
Are the laws of gravity incomplete? If so, why are people still talking about dark matter? Dark matter alone cannot explain a nearly constant rotation curve with the current laws of gravity, right?
I watched a series of videos found in the LPPFusion channel on youtube called The Real Crisis in Cosmology. In them Eric Lerner claims to answer problems in cosmology including your constant galaxy rotation curve without using dark matter or modifying gravity. I think they are at least enjoyable to watch.

Suzianne
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@metal-brain said
When I first read that galaxy rotation curve is nearly constant I immediately realized that is not how the accepted laws of gravity are supposed to work. If the laws of gravity cannot explain the nearly constant rotation curve then the laws of gravity must be incomplete.

Surely I could not be the only person to deduct that so I looked into it and I was right, others n ...[text shortened]... atter alone cannot explain a nearly constant rotation curve with the current laws of gravity, right?
This is why the Science forum people want you out of their forum.

If there's anywhere on this website that should be governed by facts, it's the Science Forum, but you still puke out your bizarro ideas there regularly.

Suzianne
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@athousandyoung said
Take it to the Science forum Spanky
They don't want him, either.

MB

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@suzianne said
This is why the Science forum people want you out of their forum.

If there's anywhere on this website that should be governed by facts, it's the Science Forum, but you still puke out your bizarro ideas there regularly.
LOL!

What are you disputing? Be specific. What do you think is the bizarro idea?

MB

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@jerryh said
I watched a series of videos found in the LPPFusion channel on youtube called The Real Crisis in Cosmology. In them Eric Lerner claims to answer problems in cosmology including your constant galaxy rotation curve without using dark matter or modifying gravity. I think they are at least enjoyable to watch.
I watched episode 4 where he explains why there is no dark matter, but which one does he talk about Modified Newtonian Dynamics?

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@metal-brain said
I watched episode 4 where he explains why there is no dark matter, but which one does he talk about Modified Newtonian Dynamics?
I'm not sure if he discusses MOND, he doesn't use it to explain galaxy rotation. He suggests the velocity curve is explained by normal gravitation and magnetic fields alone. Look to 15:45 of episode 5, but these ideas are interdispersed throughout.

MB

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@jerryh said
I'm not sure if he discusses MOND, he doesn't use it to explain galaxy rotation. He suggests the velocity curve is explained by normal gravitation and magnetic fields alone. Look to 15:45 of episode 5, but these ideas are interdispersed throughout.
Eric Lerner said the universe is too old for the big bang. I don't know where he is getting his numbers from though. I did look into quasars since they are super massive black holes.

https://www.livescience.com/most-distant-quasar-with-jets.html

It does seem like super massive black holes would take more time than a billion years to form, but I guess it is possible. But I also ran across some people that claim we cannot see the universe past a certain limit. If that is true it seems like that should prove the universe is a lot older than 13 billion years.

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