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A Physicist Who Denies Dark Matter

nautil.us

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Re: A Physicist Who Denies Dark Matter

#51

Post by maratd »

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 a very distant galaxy

It's entirely possible our equations do not function well on those scales.

Re: A Physicist Who Denies Dark Matter

#52

Post by yorwba »

TillE wrote: post #29
olavk wrote: post #27

Earlier quoted context omitted.

There was/is nothing magic about epicycles. Epicycles was part of a model which described the movement of the planets. Now we have better and more precise model, but that does not mean epicycles was "magic". There is nothing magic about the the word "dark matter" either. Yes indeed it describe a phenomen we don't understand, this does not mean it is magic.

Epicycles were wrong . They were an incorrect theory attempting to fit the math.

Using epicycles just means to decompose the motion into its Fourier series. It may not be the most elegant description, but its not wrong per se, either.

Re: A Physicist Who Denies Dark Matter

#53

Post by vivekd »

_ph_ wrote: post #49
vivekd wrote: post #41

Earlier quoted context omitted.

>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…

>>How do you explaining gravitational lensing with no visible mass, without dark matter? >Black holes? Well, black holes are not really black, you can see their accretion disk. Also, a centralized huge mass would create a different velocity profile from what we are seeing. So black holes are pretty much out.

I am not certain about the mechanics of it, but one of the most prominent theories right now is that dark matter is actually primordial black holes 1.

1. https://www.nasa.gov/feature/goddard/2016/nasa-scientist-sug...

Re: A Physicist Who Denies Dark Matter

#54

Post by RockyMcNuts »

nightcracker wrote: post #42
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…

In the scenario you're describing a black hole would qualify, however IIRC there are other aspects of dark matter that black holes can't explain.

If you assume a black hole, only certain masses and distances work, and they lens other objects.

Picture I had was, if you had multiple objects affected, you could map the distribution of the gravitational anomaly, but it's over my head in terms of what the math and the assumptions are.

Re: A Physicist Who Denies Dark Matter

#55

Post by [deleted] »

hwillis wrote: post #34
douche wrote: post #19

Earlier quoted context omitted.

I'm not seeing anything there that isn't a handwavey explanation for "reality doesn't match the models, so DARK MATTER!"

>One of the recent most convincing things was the bullet cluster as described here.[1] We saw two galaxies collide where the "observed" matter actually underwent a collision but the gravitational lensing kept moving un-impeded which matches the belief that the majority of mass in a galaxy is collisionless dark matter that felt no colliding interaction and passed right on through bringing the bulk of the gravitational…

[deleted]

Re: A Physicist Who Denies Dark Matter

#57

Post by [deleted] »

badosu wrote: post #44
shakna wrote: post #7

Earlier quoted context omitted.

Maybe I can expand. I can deny the Earth is flat, because there is an abundance of evidence that it is round. I can't deny that there are 650 elements, because as far as I know, other elements may be discovered. But I can certainly doubt it, and supply alternative theories. I can deny allegations of wrong doing, because they either happened, or didn't. But Dark Matter isn't assured yet. Denying it means it either exi…

Dark Matter is not just 'something we don't understand yet'. It has predictable effects on observations and adheres to some properties, see: https://en.wikipedia.org/wiki/Bullet_Cluster .

[deleted]

Re: A Physicist Who Denies Dark Matter

#58

Post by JoBrad »

Koshkin wrote: post #13
shakna wrote: post #2

The title is irritating. This is an interview with Milgrom, covering the man more than MOND. But, dark matter isn't something to be denied. Because it isn't understood yet, to the point where we can doubt its existence. We don't have all the answers yet, where denial rejects something as patently false. But, "The man who has an alternative to Dark Matter", is a far less attractive title for those clicks.

It appears to be a very common trend. Modern mass culture creates more interest in people's personalities than in anything else. I feel it every day myself, when I can't help noticing how easy it is for any serious discussion to quickly decay into talking about someone's personal traits, habits or preferences.

Humans have evolved for thousands of years to be social creatures, and to judge the merits of things that they may not understand by the characteristics of the person championing them. That's not modern mass culture, it's the way humans operate. I personally think it's also why many scientists fail to convince people versus (comparatively) charismatic novices.

Re: A Physicist Who Denies Dark Matter

#59

Post by douche »

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

Re: A Physicist Who Denies Dark Matter

#60

Post by JoBrad »

solotronics wrote: post #6

the non light emitting mass could be Dyson spheres of space based computers

We're compelled to choose the option which requires the fewest assumptions. Dyson spheres involve a level of assumptions far beyond dark matter and dark energy. There would have to be Dyson spheres everywhere, that do not radiate heat, and that support some civilization that leaves very few traces.
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