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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

#101

Post by pixl97 »

dnautics wrote: post #63
pixl97 wrote: post #57

Earlier quoted context omitted.

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…

I mean sure nature has no obligation to not have a unfalsifable particle, but you wind up in weird places, like, there exists a distribution of dark matter that explains the poltergeist that knocked over your coffee cup last week.

I mean I don't believe a particle that only reacts with gravity is unfalseifiable , it's that gravity just demands the use of unimaginable energies that we've not accomplished at this time.

You act like we've managed to probe the depths of physics with certainty when in reality you find any means to reject that which offends your sensibilities.

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

#102

Post by jiggawatts »

ReptileMan wrote: post #3
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…

Once I joked that a lot of things in the universe make sense if you view it as a "simulation with optimizations like lazy loading".

The analogy goes surprisingly far:

- Locality is a consequence of the use of a scaled compute cluster with peer-to-peer networking only.

- The speed of light is the speed of information exchange between compute nodes.

- General Relativity is caused by network links with finite bandwidth taking longer to exchange information if there is more of it. (Effectively slowing down time)

- Quantum Mechanics is caused by finite precision of the n-bit numbers at small scales.

- MOND is caused by cumulative summation and rounding errors that show up only in the case of weak fields over large distances.

Etc…

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

#103

Post by wwarner »

sigbottle wrote: post #87
wvenable wrote: post #83

Earlier quoted context omitted.

> Ok, so... why do people take it seriously as a concept? Historically, science has predicted lots of true things about the universe that could not be observed at the time.

I don't know what or why our science education is like this, but it seems like everybody's understanding of science bottomed out at a straw man version of popper & positivism. And to be clear, falsification and being empirical & skeptical about theoretical claims is great. What I see all too often on the Internet is just pattern matching to the words "observable" and "falsification" without a second thought, without…

I feel the same, but then I remind myself of how I used to feel about dark matter (I really disliked it). Having an arena where no scientific question is out of bounds is great.

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

#104

Post by ricksunny »

yongjik wrote: post #82
ricksunny wrote: post #67

If it had failed, would we be hearing about it in Science before the researchers continued testing it until it passed? (i.e. is this a blindspot in our collective epistemology?)

If it had failed it would've been a top science news. Every scientist dreams about the day when they're mentioned as "(...)'s experiment puts Newton's law of gravity in jeopardy."

Would it? Or would it be treated as an errant experiment by either the journal or the experimentalists themselves, foregoing publishing until they had a result that was better aligned with established norms? Rightly or wrongly, I expect that stakeholders would tend to invoke Sagan’s ECREE over the course of the publication process.

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

#105

Post by tsimionescu »

Joker_vD wrote: post #48
_ZeD_ wrote: post #42

Earlier quoted context omitted.

Or, you know, as aether. It's a scientific theory. It's the best that we have right now to model the real world and be able to do prediction on its behavior. Does it seems to be kept together by duct tape? Maybe. Is it yet useful? Yep. Will it be discarded if anything more fitting will came up? You can be sure of it.

Yeah, pretty much, which is why this adherence to dark matter seems even more puzzling: we already had a mysterious substance with nonsensical mechanical properties (perfectly solid, but has zero collision) that turned out to be completely superfluous; the actual answer was the different shape of the physical laws. Now we again have a mysterious substance with nonsensical properties (has gravitational pull, doesn't i…

Except that there is nothing nonsensical about a particle that has mass and doesn't participate in any SM interaction. It's inconvenient if such a particle exists, as it's very very hard to detect things precisely by their gravitational effects, but there is nothing nonsensical, or even particularly weird, about the idea. Plenty of particles only interact with a few of the SM forces - e.g. photons are not affected by the strong force, nor are electrons, neutrinos are affected by neither the strong force nor EM, only the weak force, gluons only interact with the strong force, not EM nor the weak force, etc

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

#106

Post by peterfirefly »

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…

No, it's not quite "no guess at all". Using gravitational lensing to estimate how much mass there is in a part of a galaxy is pretty smart. It turns out that there sometimes indeed is mass (because the lensing is there) even though it doesn't seem to give off much light.

(But I don't really believe in dark matter, either. It's mostly epicycles and phlogiston.)

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

#107

Post by SiempreViernes »

hammock wrote: post #99
cactacea wrote: post #84

Earlier quoted context omitted.

Because stuff like the Bullet Cluster exists. Dark matter is in fact the simplest answer. https://en.wikipedia.org/wiki/Bullet_Cluster

Angry gods used to be the simplest answer for a lot of things. Inevitably we find a better model

You are of course very welcome to propose this supposed better model, but please do some due diligence and learn to roughly understand the current flawed models firsts.

For example "angry gods" was never a simple theory, one needs only to read some fan fiction to understand that theology gets complicated fast. Instead "angry gods" is a simplified summary of a very complicated theory about metaphysical hierarchy, creation, agency, the meaning of divinity, and cause and effect, etc etc.

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

#108

Post by pdonis »

dnautics wrote: post #60
pessimist wrote: post #53

Earlier quoted context omitted.

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 severa…

> 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).

My take on this is a bit different. The obvious way to get a relativistic theory that looks like MOND is to add a scalar field. (And possibly a vector field, as in TeVeS.) But from a relativistic, quantum field theory perspective, adding more fields is just...adding a new type of "matter". I.e., dark matter!

In other words, when you take relativity into account, "MOND" and "dark matter" don't really look like two different possibilities any more. They just look like two different ways of describing the same math in imprecise ordinary language.

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

#109

Post by ShinyLeftPad »

davrosthedalek wrote: post #97
ShinyLeftPad wrote: post #91

Earlier quoted context omitted.

We don't measure dark matter, we measure some anomaly and then we say "it must've been dark matter". It's not crazy different from saying the same about that poltergeist.

We measure the matter distribution by its affect on light (strong/weak lensing). We also measure the matter distribution by the amount of light coming from it. The results are not the same. The simplest explanation is that there is matter which does not produce or reflect light via e/m, i.e. it is dark. Dark Matter. We know of particles which behave the same way. Neutrinos for example.

You're saying the same thing, we see some anomaly in measured light and we say "the simplest explanation is dark matter".

We are not measuring dark matter, we are measuring something that is not what we expect and we decided it's dark matter.

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

#110

Post by SiempreViernes »

fooker wrote: post #79
messe wrote: post #45

Earlier quoted context omitted.

It was far from exactly like that. GR was in part prompted by the precession of the perihelion of mercury for which there was plenty of data.

Look at the timeline here https://en.wikipedia.org/wiki/Tests_of_general_relativity

Dude, if you genuinely want to know what happened, you should read some proper history of science. Here take this: https://arxiv.org/pdf/physics/0405066

It shows both how Einstein very much didn't make the theory alone, was inspired to take impotat technical steps by work of other thats that created a theory based on his principles before him, and that actually he first created (in intense collaboration) a failed theory that got Mercury's anomaly all sorts of wrong.

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