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Newton's law of gravity passes its biggest test

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Re: Newton's law of gravity passes its biggest test

#31

Post by anthonypasq »

fooker wrote: post #19
GuB-42 wrote: post #2

If you follow Sabine Hossenfelder's channel, she has a MONDOmeter. With MOND (modified Newtonian gravity) on one side and dark matter on the other side. As new papers come out the needle goes back and forth, and I guess that she will make a new video if she hasn't already, with the needle moving one step towards dark matter. I find it interesting how it doesn't seem to settle. Dark matter is still the favorite, but t…

We are likely going to find out that both are unfixably faulty. It'll take either the next Einstein or some groundbreaking experimental observation to get there in my opinion. If it was possible to incrementally fix these theories, the army of postdocs working on these would have already done so in the last decade or so.

you think the deepest mysteries of reality and the universe should just reveal themselves because we have a couple thousand smart people working on it for... 10 years?

Re: Newton's law of gravity passes its biggest test

#32

Post by wetpaws »

adgjlsfhk1 wrote: post #21
PaulHoule wrote: post #4

Earlier quoted context omitted.

MOND does amazingly well at galactic rotation curves, less well at anything else. If you think it started with Vera Rubin in 1966 MOND seems natural, but if you know that it started with Fritz Zwicky in 1933 than dark matter is easier to believe.

MOND only really does well on galactic rotation curves because it has free parameters that are tuned to "predict" the correct answer for galactic rotation curves.

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Re: Newton's law of gravity passes its biggest test

#33

Post by wetpaws »

cowl wrote: post #28
gus_massa wrote: post #26

Earlier quoted context omitted.

We make a similar guess for the stuff that is in the center of Earth. We measure local gravity and speed of sound velocity, and we guess here is liquid, here is solid, here is this rock, here is this another rock [1]. See for example https://www.livescience.com/64943-nobody-understands-the-gia... nobody has seen them, we guess they are there. Dark matter is another guess. We guess there is more matter in galaxies tha…

Dark matter is not another Guess. is no guess at all. its the same as saying the center of the earth is made of Dark Core. and when someone proposed liquid core, there would be papers how a liquid core doesnt explain 100 %, and neither does rock or solid so Dark Core it is because it's sIMpLer to have just one Dark Something than 3 different somethings to explain anything. The fact that there are tentatives to identi…

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Re: Newton's law of gravity passes its biggest test

#34

Post by NewEntryHN »

magicalhippo wrote: post #10
Lvl999Noob wrote: post #7

I thought newtonian gravity was already proven to be inaccurate with Einstein's Special Relativity (or General Relativity?) giving better results on cosmic scales (basically analogous to an approximation vs an exact formula)?

General Relativity reduces to Newtonian gravity as the curvature goes to zero, that is when you're very far away from objects relative to their masses, for slow non-relativistic objects like stars and galaxies. Galaxies are typically so far away from another they're almost like point sources to each other, hence Newtonian gravity explains their motion very well. However, inside galaxies things do not behave as expect…

Why is the article titled "Newton's law of gravity passes its biggest test" if it doesn't explain the movement more than MOND?

Re: Newton's law of gravity passes its biggest test

#35

Post by NewEntryHN »

GuB-42 wrote: post #9
Lvl999Noob wrote: post #7

I thought newtonian gravity was already proven to be inaccurate with Einstein's Special Relativity (or General Relativity?) giving better results on cosmic scales (basically analogous to an approximation vs an exact formula)?

At these scales (entire galaxies, very weak forces), it doesn't make a significant difference. There are ways of adapting MOND to match general relativity, should it turn to be correct at explaining what it is supposed to explain (like the movement of galaxies).

I think OP's question is more how could Newton's law "pass" a test any more than General Relativity would, considering that it's merely an edge case of GR?

Re: Newton's law of gravity passes its biggest test

#36

Post by raverbashing »

GuB-42 wrote: post #2

If you follow Sabine Hossenfelder's channel, she has a MONDOmeter. With MOND (modified Newtonian gravity) on one side and dark matter on the other side. As new papers come out the needle goes back and forth, and I guess that she will make a new video if she hasn't already, with the needle moving one step towards dark matter. I find it interesting how it doesn't seem to settle. Dark matter is still the favorite, but t…

MOND is kinda like a dead horse now, that people like to keep flogging

I think it's possible for an alternative gravitational law to work, but not MOND

MOND is stronger at longer distances than Newtonian Gravity. To me that does not pass the sniff test. It could be a step in understanding a more exact law but to me it feels weird

Re: Newton's law of gravity passes its biggest test

#37

Post by htx80nerd »

GuB-42 wrote: post #2

If you follow Sabine Hossenfelder's channel, she has a MONDOmeter. With MOND (modified Newtonian gravity) on one side and dark matter on the other side. As new papers come out the needle goes back and forth, and I guess that she will make a new video if she hasn't already, with the needle moving one step towards dark matter. I find it interesting how it doesn't seem to settle. Dark matter is still the favorite, but t…

Dark Matter : supposedly makes up a big amount of the mass of the universe, but cant be seen, does not emit, absorb, or reflect light. Also it can 'pass through' other normal matter, and other dark matter.

It's basically magic aka not actually real, just something in vogue to pretend is real at the present moment.

Re: Newton's law of gravity passes its biggest test

#38

Post by GuB-42 »

cowl wrote: post #18
GuB-42 wrote: post #2

If you follow Sabine Hossenfelder's channel, she has a MONDOmeter. With MOND (modified Newtonian gravity) on one side and dark matter on the other side. As new papers come out the needle goes back and forth, and I guess that she will make a new video if she hasn't already, with the needle moving one step towards dark matter. I find it interesting how it doesn't seem to settle. Dark matter is still the favorite, but t…

It's funny how for MOND we cant accept that it has some unknowns yet but we are more than willing to accept the FULL UNKNOWN Dark Matter. it's easy. put "Dark" in front of something and you don't have to explain it at all, no matter that something else explains at least 60-70% instead of 0.

Dark matter is invisible, but it isn't magic. It is not significantly different from neutrinos. No one seriously denies the existence of neutrinos nowadays, even though they are invisible (i.e. they don't interact electromagnetically).

Dark matter is actually a very parsimonious theory. None of the laws of physics have to change to accommodate it, unlike with MOND. We may not see it, but it has to move around and affect normal matter in predictable patterns consistent with our current understanding of physics. If it doesn't, then the theory is wrong and may need some revision (which may be a dark matter + MOND hybrid).

In parallel with the research that attempts to find the properties of dark matter that best describe our observations is research that attempt to find what other properties it may have. It is a new particle? Can it interact in ways other than gravity? We didn't find anything, but the universe is under no obligation to make things easy for us.

One possible idea called the "nightmare scenario" is that dark matter is made of particles that only interacts gravitationally. It is a perfectly fine theory, maybe the cleanest one, but unfortunately, it would mean that we may never be able to detect these particles because gravity is so weak that the required detectors would be way beyond our technological abilities.

Re: Newton's law of gravity passes its biggest test

#39

Post by njarboe »

htx80nerd wrote: post #37
GuB-42 wrote: post #2

If you follow Sabine Hossenfelder's channel, she has a MONDOmeter. With MOND (modified Newtonian gravity) on one side and dark matter on the other side. As new papers come out the needle goes back and forth, and I guess that she will make a new video if she hasn't already, with the needle moving one step towards dark matter. I find it interesting how it doesn't seem to settle. Dark matter is still the favorite, but t…

Dark Matter : supposedly makes up a big amount of the mass of the universe, but cant be seen, does not emit, absorb, or reflect light. Also it can 'pass through' other normal matter, and other dark matter. It's basically magic aka not actually real, just something in vogue to pretend is real at the present moment.

Dark Unknown Matter would be a better name for lay people to understand what's going on. I'm no cosmologist but isn't it just a placeholder for something that gravity interacts with (and not much else) and we don't know what it currently is. When we discover what it is the name will change.

Re: Newton's law of gravity passes its biggest test

#40

Post by yfontana »

cowl wrote: post #28
gus_massa wrote: post #26

Earlier quoted context omitted.

We make a similar guess for the stuff that is in the center of Earth. We measure local gravity and speed of sound velocity, and we guess here is liquid, here is solid, here is this rock, here is this another rock [1]. See for example https://www.livescience.com/64943-nobody-understands-the-gia... nobody has seen them, we guess they are there. Dark matter is another guess. We guess there is more matter in galaxies tha…

Dark matter is not another Guess. is no guess at all. its the same as saying the center of the earth is made of Dark Core. and when someone proposed liquid core, there would be papers how a liquid core doesnt explain 100 %, and neither does rock or solid so Dark Core it is because it's sIMpLer to have just one Dark Something than 3 different somethings to explain anything. The fact that there are tentatives to identi…

> at it's core (pun intented) Dark matter is something to make equations fit without any other thought behind it or whether there might be several things behind it or god forbid that we juddge the equations themselves

Another way to interpret dark matter is that we can observe something using several different ways, but all those ways use gravity. When trying to observe this something using electromagnetism, we see nothing. It doesn't seem so crazy then to hypothesize that this something only interacts with gravity, and not electromagnetism.

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