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A Physicist Who Denies Dark Matter

nautil.us

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Re: A Physicist Who Denies Dark Matter

#91

Post by hwillis »

Animats wrote: post #56

Dark matter is at best a hypothesis. We can't find any. We can't make any. It's a hack to fix theory.

It is not. Dark matter is not some smooth distribution that could be explained by adjusting the formula for gravity. There are places where it is, and places where it isn't. Not only that, but it has its own mass and inertia.

Not only that but dark matter is missing in a host of other ways that can't be explained by the laws of gravity being more complex. Microwave background radiation is 30x more powerful than can be explained by visible matter, but matches exactly if you add in dark matter and dark energy. The ratio of hydrogen to deuterium is inconsistent with visible matter, but matches perfectly if you add dark matter.

Galaxy clusters collide and we can literally see dark matter pass through the collision since it doesn't interact.

Dark matter is as well proven as the atom was when we made the bombs. We just don't know what it's made of yet. You simply don't know enough about it.

Re: A Physicist Who Denies Dark Matter

#92

Post by jrvidal »

vivekd wrote: post #85
jrvidal wrote: post #75

Earlier quoted context omitted.

Sorry, but I don't understand your argument. When asked 'how do you explain lensing without dark matter?', your answer is 'with this particular flavor of dark matter'?

Well we're seeing a bunch of stuff happening out there and calling it dark matter. 1. The big problem is not enough stuff. Galaxies don't have enough stuff in them to let gravity hold them together. 2. A second problem is that we have stuff out there that our instruments can't detect but seems to be putting out gravity and bending the light. The orthodoxy of dark matter says 1 and 2 are connected. That dark matter is…

I see now, makes sense.

Re: A Physicist Who Denies Dark Matter

#93

Post by hwillis »

chmike wrote: post #83

A.Meessen suggest a simpler explanation. Dark matter is made of electrically neutral elementary particles subject to scattering and a pressure. These particles may combine and dissociate which accounts for drak energy and the cosmological constant. The properties of all elementary particles (except mass) are predicted by his space time quantization (STQ) theory. It provides a blue print of all elementary particles. I…

Yeah, he also thinks that UFOs exist. He's a nutjob

Re: A Physicist Who Denies Dark Matter

#94

Post by jcranmer »

douche wrote: post #59
douche wrote: post #9

Dark matter appears, to a layman with some historical knowledge, as nothing more than modern day epicycles. When we can't explain something with the models we have, and have to invent magic terms to balance the equations, that indicates that we really don't know what the fuck is going on.

Whoo, boy, the astrophysics fanboys that come out of the woodwork to suppress the notion that the emperor has no clothes

Even as someone who would rather MOND be true than dark matter, I have to admit that dark matter is internally consistent in ways that MOND is not.

By comparison to the theories of planetary movement (since you seem to love comparing dark matter to them so much), MOND is rather like the Copernican model and dark matter rather like Kepler's model. It's well-known that the traditional equations are off. MOND provides a fix that starts off looking better, but the more precise you do the measurements, the more you need to add the fudge factors in to make the numbers come out right, and it ends up being just as bad as the original--which is a reasonable description of the evolution of the Copernican model. By contrast, both Kepler's model and dark matter provide a much more accurate picture with a somewhat more complex addendum to the original non-fudged equations. But they also both lack mechanistic explanations for their origin: Kepler's model ruined the traditional explanation of how planets moved and inherited the stellar parallax death-knell from Copernicus's theory.

In the case of planetary motion, it took the development of Newton's Law of Gravitation and the derivation of Kepler's laws of planetary motion from said theory to provide a sound mechanistic basis. We lack that mechanistic basis for dark matter, but that doesn't really mean that dark matter is inherently wrong.

Re: A Physicist Who Denies Dark Matter

#95

Post by boomboomsubban »

kradem wrote: post #84
boomboomsubban wrote: post #81

Earlier quoted context omitted.

"Proven theory" isn't a thing, Milgrom is a scientist, he should be well aware of that. Using truth conditional logic here just doesn't make sense.

This subthread deals with the completely different issue, it's about bad logic. No matter how well Milgrom and/or his theory could be discredited, that doesn't change the fact we can dismiss something prior to fully understand it. It doesn't matter if that - what we dismissed - shapeshifts into something completely different (or similar...) afterward, on the contrary, regarding resources spent it would be sad if not.

>This subthread deals with the completely different issue, it's about bad logic. No matter how well Milgrom and/or his theory could be discredited, that doesn't change the fact we can dismiss something prior to fully understand it

It's not bad logic, it only seems like it is because you're approaching it from an Aristotlean view of logic. These things can't be proven, so dismissing them is never an option in science.

Re: A Physicist Who Denies Dark Matter

#96

Post by shakna »

kradem wrote: post #84
boomboomsubban wrote: post #81

Earlier quoted context omitted.

"Proven theory" isn't a thing, Milgrom is a scientist, he should be well aware of that. Using truth conditional logic here just doesn't make sense.

This subthread deals with the completely different issue, it's about bad logic. No matter how well Milgrom and/or his theory could be discredited, that doesn't change the fact we can dismiss something prior to fully understand it. It doesn't matter if that - what we dismissed - shapeshifts into something completely different (or similar...) afterward, on the contrary, regarding resources spent it would be sad if not.

The title is bad, because it lacks the eloquence that befits a journalist.

Milgrom has provided an alternative to Dark Matter.

He isn't on a street corner shouting it doesn't exist. He didn't set out to disprove the theory. He took some evidence and reinterpreted it.

Re: A Physicist Who Denies Dark Matter

#97

Post by hwillis »

vivekd wrote: post #41
RockyMcNuts wrote: post #11

How do you explaining gravitational lensing with no visible mass, without dark matter? In other words situations where we see twin images of a very distant galaxy because light curves around intervening mass, without sufficient mass observable to explain the deflection? I was under the impression that we could map dark matter localized to a precision that tended to rule out measurement error or a general divergence f…

>How do you explaining gravitational lensing with no visible mass, without dark matter? Black holes? The physicist says: >What struck me was some regularity in the anomaly. The rotational velocities were not just larger than expected, they became constant with radius. Why? Sure, if there was dark matter, the speed of stars would be greater, but the rotation curves, meaning the rotational speed drawn as a function of…

Can't be black holes. For one thing they would start becoming visible through Hawking radiation if they were small enough to be homogenous like dark matter. Secondly baryon acoustic oscillations set a limit on how many black holes there can be.

For your second part, the constant velocity is very well explained. The dark matter is just very broadly distributed. That's a natural consequence of not interacting with anything. It clumps up much less.

Re: A Physicist Who Denies Dark Matter

#98

Post by hwillis »

signa11 wrote: post #46
RockyMcNuts wrote: post #11

How do you explaining gravitational lensing with no visible mass, without dark matter? In other words situations where we see twin images of a very distant galaxy because light curves around intervening mass, without sufficient mass observable to explain the deflection? I was under the impression that we could map dark matter localized to a precision that tended to rule out measurement error or a general divergence f…

> How do you explaining gravitational lensing with no visible mass, without dark matter? black hole would produce the same result right ?

No. Dark matter is spread relatively homogeneously so you would need very small back holes, and those would be visible or wouldn't have existed this long. Baryon acoustic oscillations also limit how much normal matter we can have, and they say there has to be a great deal of non-baryonic matter.

Re: A Physicist Who Denies Dark Matter

#99

Post by hwillis »

maratd wrote: post #51
RockyMcNuts wrote: post #11

How do you explaining gravitational lensing with no visible mass, without dark matter? In other words situations where we see twin images of a very distant galaxy because light curves around intervening mass, without sufficient mass observable to explain the deflection? I was under the impression that we could map dark matter localized to a precision that tended to rule out measurement error or a general divergence f…

When we're confronted with something we can't explain using our existing equations and theories, the conclusion is that there must be some mysterious thing there that fixes our current equations and makes them work again? A thing we can't detect or see or have any other evidence of ... other than our equations and theories need that thing there for them to work? > In other words situations where we see twin images of…

Dark matter is predicted at every level of astrophysics. It's not just "hey, galaxies look weird".

The amount of visible matter only accounts for 4% of the cosmic microwave background.

The CMB is extremely smooth, but visible matter is highly clumped up. This can only be explained by a huge amount of matter that doesn't clump up ie non-baryonic.

The ratio of deuterium to hydrogen rises based on the density, since there's more pressure from gravity. There's way more deuterium than can be explained by visible matter, so there must be some extra compression happening.

Galaxies have more kinetic energy than they can have given their visible matter and how fast it's moving. This implies a huge amount of invisible mass.

Gravitational lensing around the edges of galaxy clusters indicates a halo of invisible mass.

Colliding galactic clusters show their mass splits into two parts: one that clumps up into a bright, dense blob, and another that has much higher inertia and continues past the bright blob as if it didn't interact with it in any way besides gravity.

We can map variations in empty space where there is more mass than is expected, in a way that can't be explained by a self-consistent theory of gravity but can be explained by invisible mass.

Dark matter as a theory hasn't changed for 80 years and every single one of these discrepancies is solved exactly by using the measurements of dark matter that already existed. They all agree with each other perfectly. There is no theory that even competes with dark matter. Nobody has come up with another idea that explains all of those or even most of those problems.

Re: A Physicist Who Denies Dark Matter

#100

Post by hwillis »

douche wrote: post #89
hwillis wrote: post #87

Earlier quoted context omitted.

That's total nonsense.

A.) God waved his finger, and the universe sprang into existence. B.) something happened, and the universe sprang into existence.

A.) God waved his finger, and the universe sprang into existence, along with a bunch of mythology.

B.) something happened, and the universe exploded from a single point.

And meanwhile we have no evidence of god, and a crapload of evidence that the whole universe is expanding outwards.

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