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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

#51

Post by Centigonal »

rappatic wrote: post #41

When I see dark matter in the news I'm always reminded of the story of Vulcan. In the 1800s, detailed observations of the planet Mercury showed that its orbit was slightly different than Newtonian mechanics predicted-- a difference of about 43 arcseconds per century. The study was rigorous enough to rule out any observation errors. Le Verrier, the astronomer who made these observations, wondered how to explain the di…

yes - absent experimental confirmation, the effects attributed to dark matter may in fact be due to an unrelated as-yet-undiscovered phenomenon.

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

#52

Post by bilkow »

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…

> I mean we got relativity because of a minor discord with newtonian Laws. (the orbit of Mercury).

I don't think that's true. One of Einstein's test for General Relativity, using Mercury's orbit, came around 10 years later after special relativity was proposed, which is understood to be motivated by both Maxwell's equations and experimental results suggesting that the speed of light (electromagnetic waves) not depending on the frame of reference. General relativity (explaining gravity) seem to have been motivated by Newton's gravity not playing well with Special relativity (with mass being relative and all).

I understand the frustration with Dark Matter, but my understanding is that Dark Matter is a guess that is known to be incomplete. Scientists are shooting everywhere to try to explain the discrepancy in gravitational effects and some form of undetected matter is currently the best hypothesis (but not the only one). You say that "we accept 90% observation disaccordance", but the source of its effect is being searched for.

See:

- https://hsm.stackexchange.com/questions/622/what-was-einstei...

- https://en.wikipedia.org/wiki/History_of_gravitational_theor...

- https://en.wikipedia.org/wiki/Tests_of_general_relativity

Edit: formatting, updated links

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

#53

Post by pessimist »

rappatic wrote: post #41

When I see dark matter in the news I'm always reminded of the story of Vulcan. In the 1800s, detailed observations of the planet Mercury showed that its orbit was slightly different than Newtonian mechanics predicted-- a difference of about 43 arcseconds per century. The study was rigorous enough to rule out any observation errors. Le Verrier, the astronomer who made these observations, wondered how to explain the di…

There are multiple independent observations pointing toward dark matter:

1. Galaxy rotation curves. 2. Galaxy cluster mass measurements from gravitational lenses and infrared. 3. Cosmic Microwave Background models (mass measurements from inhomogeneities that correspond to acoustic waves, for eg).

MOND only explains 1.

Dark matter accounts for all 3. Only catch is that it hasnt been directly observed.

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

#54

Post by lukeify »

rappatic wrote: post #41

When I see dark matter in the news I'm always reminded of the story of Vulcan. In the 1800s, detailed observations of the planet Mercury showed that its orbit was slightly different than Newtonian mechanics predicted-- a difference of about 43 arcseconds per century. The study was rigorous enough to rule out any observation errors. Le Verrier, the astronomer who made these observations, wondered how to explain the di…

The constituent particles of nature are under no requirement to be apparent or achievable to you.

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

#55

Post by gus_massa »

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…

> just one Dark Something than 3 different somethings to explain anything

There are many candidates and I think nobody discarded it's a mix, it looks like a plausible scenario. I made a quick look in Wikipedia, but I didn't find anything relevant to a mix of Dark Mater.

There is(was?) some big discussion about cold vs hot (and warm?) dark mater. IIUC "cold" dark mater won. I'm not sure if there is enough details to make a good guess of the split, or if it's a 100.00% vs 0.00% case.

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

#56

Post by [deleted] »

pessimist wrote: post #53
rappatic wrote: post #41

When I see dark matter in the news I'm always reminded of the story of Vulcan. In the 1800s, detailed observations of the planet Mercury showed that its orbit was slightly different than Newtonian mechanics predicted-- a difference of about 43 arcseconds per century. The study was rigorous enough to rule out any observation errors. Le Verrier, the astronomer who made these observations, wondered how to explain the di…

There are multiple independent observations pointing toward dark matter: 1. Galaxy rotation curves. 2. Galaxy cluster mass measurements from gravitational lenses and infrared. 3. Cosmic Microwave Background models (mass measurements from inhomogeneities that correspond to acoustic waves, for eg). MOND only explains 1. Dark matter accounts for all 3. Only catch is that it hasnt been directly observed.

[deleted]

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

#57

Post by pixl97 »

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.

I mean it's easy to say it's fake, but to counter this, why can a particle that only interacts with gravity not exist?

The neutrino is a good example of a particle that almost doesn't exist. They are produced in solar reactions in spectacular amounts. Trillions of them are flitting through you right now as if you don't exist. You'd need a light year block of lead to ensure you could stop one. Mind-boggling amounts of them have to pass through our detectors to see even a single interaction.

Simply put, the particle physics does not have to behave nice so you can sleep well at night.

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

#58

Post by pixl97 »

davrosthedalek wrote: post #15
cvoss wrote: post #8

Earlier quoted context omitted.

This comment and GP are two of the most concise and punchy descriptions I've ever heard of some of the deepest aspects of modern physics. On the one hand we have principles of locality and finite propagation speed, which limit the computational work to a small neighborhood, and on the other hand we have principles of non-locality and superposition, which cause the computation to explode as it swallows up potentially…

It might just be a reflection of the architecture the universe simulation is running on...

See Timmy, this is what happens when you run your universe on a holographic medium at an infinite distance.

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

#59

Post by lubujackson »

rappatic wrote: post #41

When I see dark matter in the news I'm always reminded of the story of Vulcan. In the 1800s, detailed observations of the planet Mercury showed that its orbit was slightly different than Newtonian mechanics predicted-- a difference of about 43 arcseconds per century. The study was rigorous enough to rule out any observation errors. Le Verrier, the astronomer who made these observations, wondered how to explain the di…

100%. It's important to realize our understanding of "dark matter" is fuzzy because we only understand it through data anomalies. Dark matter is a classic catch-all concept that we use as a crutch while we try to understand the underlying system better.

Similar to how we used to believe in "aether" to explain how light could travel through empty space. It is important to understand how these crutches help and hinder understanding.

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

#60

Post by dnautics »

pessimist wrote: post #53
rappatic wrote: post #41

When I see dark matter in the news I'm always reminded of the story of Vulcan. In the 1800s, detailed observations of the planet Mercury showed that its orbit was slightly different than Newtonian mechanics predicted-- a difference of about 43 arcseconds per century. The study was rigorous enough to rule out any observation errors. Le Verrier, the astronomer who made these observations, wondered how to explain the di…

There are multiple independent observations pointing toward dark matter: 1. Galaxy rotation curves. 2. Galaxy cluster mass measurements from gravitational lenses and infrared. 3. Cosmic Microwave Background models (mass measurements from inhomogeneities that correspond to acoustic waves, for eg). MOND only explains 1. Dark matter accounts for all 3. Only catch is that it hasnt been directly observed.

MOND explains 1.

2 is "who can say" because nobody has reconciled MOND with Relativity (not that it's impossible, it's just hard and annoying math, could be a lack of effort thing, could also be a real theoretical constraint that invalidates MOND).

3 is subject to questions like "is the CMB really what we think it is" -- if it's early thermalized dust, then that ALSO resolves hubble tension, e.g.

MOND explains several things LCDM cannot:

- why most elliptical galaxies seem to "not have dark matter" (effectively a prediction)

- external field effect (predicted and confirmed)

- renzo's rule

- DM halos that are way too big

- early galaxies (this was a prediction)

HM. people have been downvoting. Anyone care to post a substantive rebuttal?

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