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A Physicist Who Denies Dark Matter

nautil.us

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Re: A Physicist Who Denies Dark Matter

#141

Post by photon-torpedo »

moomin wrote: post #124
amai wrote: post #118

MOND might explain rotation curves of galaxies. But it doesn't explain all the other places in astrophysics, where one needs dark matter. Especially MOND (and any modification to gravity) cannot explain the Bullet Cluster: https://en.wikipedia.org/wiki/Bullet_Cluster#Significance_to... The Bullet Cluster is especially significant, because it shows gravitational lensing by dark matter spatially separated from visible…

This, whereas there's every possibility that dark matter isn't what we think it is, and holds some serious surprises, the evidence that there's a whole extra physical phenomenon (dark matter) that we've never observed seems pretty incontrovertible. Dark energy, though, currently appears to be a "stuff we really don't understand" factor.

Concerning dark energy, it might be explainable by quantum vacuum fluctuations:

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.95.10...

(the last author of that paper is rather well respected in that field)

Re: A Physicist Who Denies Dark Matter

#142

Post by quickben »

hwillis wrote: post #73
gaius wrote: post #66

Earlier quoted context omitted.

Right it's like when people say, I don't believe in Creation, that stuff is just nonsense. And you say, so what's your alternative theory then? And they reply, well there was a "big bang" and everything just sort of appeared, for no reason. Really, that's the alternative explanation?

Well yes, if you ignore all the evidence of something then you can confidently say there is no evidence. Christian genesis: There was a garden of Eden, and a god. Evidence: No garden of Eden, no evidence of angels or god, no reason those things would suddenly stop being apparent. Direct contradictory evidence that YHWH[1] was a minor god in the original jewish pantheon rather than an actual creator god. Big Bang: The…

>>Christian genesis: There was a garden of Eden, and a god.

We'll, technically, Genesis starts with a universe filled with water, and science stars with a universe filled with hydrogen (that can be detected) and potentially other stuff that can't.

On the outside, both stories are the same and have gaping holes in their logic.

Re: A Physicist Who Denies Dark Matter

#143

Post by douche »

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.

This should not be downvoted

Re: A Physicist Who Denies Dark Matter

#144

Post by JadeNB »

yorwba wrote: post #52
TillE wrote: post #29

Earlier quoted context omitted.

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.

> 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.

One issue here is that (as I understand the history) epicycles were not originally proposed in the context of "just add them until you've got something that looks right"; it was proposed that, occasionally, one needed to add one epicycle. After a while it was found that even this didn't work, and we needed sometimes to add another. I forget whether the theory collapsed before instances were found where we'd need a third.

This, I think, is 'wrong' in the sense of physics: if your model is constantly scrambling to catch up with newly acquired data, then it has no predictive, and hence little scientific, value. Further, the very ability of epicycles constantly to scramble to catch up—the ability of trigonometric polynomials to approximate continuous functions arbitrarily well over arbitrary bounded intervals, as you mention—is also a mark against them: a scientific theory that is so general that it could be tuned to predict anything can, in fact, for that reason actually predict nothing.

Re: A Physicist Who Denies Dark Matter

#145

Post by jessriedel »

BoiledCabbage wrote: post #128
jessriedel wrote: post #86

Earlier quoted context omitted.

The fact that someone with more expertise is warning that a discussion is going off the rails is a useful, constructive fact. Demanding that that person explain in detail why in order to contribute is a good way to make sure they don't bother.

The fact that someone is knowledgeable about a subject doesn't exempt them from being a constructive contributor to a discussion. Additionally, no where was it "demanded that you explain in detail". I don't mean to be too blunt here, but there is quite a huge gap of comments between a detailed explanation and what you posted. As an example: "There were a number of things incorrect in this post. The largest one of the…

1. The proper question is "When a commenter is very wrong on a technical topic, is it net-positive for someone with expertise to point this out even if they don't contribute further?". I think the answer is obviously "yes". You seem to be more concerned with whether people are pulling their fair share, vs. being exempt/special, which I claim is the wrong question.

2. Effort scales with detail. The example comment you give is 3 times the effort, and I wouldn't have made the original comment if it required that much detail. My comment took me a few seconds to write, and merely tracking down a URL link for explanation would have made it not worth it.

3. Rebutting the N-th confused post on HN about dark matter doesn't interest me, but the meta point of what contributes to a discussion does interest me.

Re: A Physicist Who Denies Dark Matter

#146

Post by kradem »

boomboomsubban wrote: post #138
kradem wrote: post #115

Earlier quoted context omitted.

>> could something be dismissed if we don't fully understand it? > No, as the entire concept of "fully understand" is ridiculous. We can't fully understand anything, so if you assume the answer is yes then we could dismiss everything. It's not a concept, it's just my lousy English and awkward abbreviation of "to the point where" with "fully". I'm here just to play a game of logic. Did we dismiss the ether at the poin…

It's not your English, I understand what you are saying, you're game of logic is using an old copy of the rules. Science doesn't dismiss things. Theories about ether were put aside when we started getting experimental results that it could not support and developed other models that explained it better. The theory still exists, and there is a possibility that someone will use it to better explain things in the future…

Thank you very much for your effort here in explaining things.

There's nothing here in the thread powered by "my logic". I'm just certain that dark matter, ether, the Holy Grail, or anything, could be abandoned in our minds once we find the prettier chick to cope with, no matter how well we understood the previous one.

Re: A Physicist Who Denies Dark Matter

#147

Post by JoBrad »

powera wrote: post #137

Between dark matter and the problems with inflation theory ( https://www.scientificamerican.com/article/cosmic-inflation-... ) I think there's enough evidence to show that the Big Bang model of the universe is flawed. As soon as somebody invents/discovers a better model, most of current research will prove itself completely useless.

Whether or not inflation theory holds long-term, I highly doubt that "most of current research will prove itself completely useless." Even if Dark Energy process to be done yet-undiscovered property of ordinary matter, the research on its effects and properties will still be very valuable.

We didn't throw out Galileo's research when Kepler discovered new principles, or Newton's when Planck and Einstein performed their research.

Re: A Physicist Who Denies Dark Matter

#148

Post by H4CK3RM4N »

Eyght wrote: post #131
knodi123 wrote: post #122

Earlier quoted context omitted.

> Especially MOND (and any modification to gravity) cannot explain the Bullet Cluster The creator of MOND addressed that: http://www.astro.umd.edu/~ssm/mond/moti_bullet.html

Your link made me very grateful for Firefox's Reader View.

Is that part of the Pocket acquisition? I was comparing Safari and Firefox a while ago and Safari's reader view was one of the deciding factors in my choice.

Re: A Physicist Who Denies Dark Matter

#149

Post by autokad »

JadeNB wrote: post #139
autokad wrote: post #82

Earlier quoted context omitted.

the big bang theory was dismissed for decades. Even Einstein said to someone suggesting it that his physics was "abominable".

> the big bang theory was dismissed for decades. Dismissing a theory that is (now known to be) right is not necessarily political; it can be just a mistake. There are certainly cliques that are invested in believing the orthodoxy, but there are ways in the hard sciences of absolutely disproving that orthodoxy; and, though they are subject to fierce scrutiny, as they should be, they can be, and have been, accepted aft…

it can be but you offered no evidence contrary. the data WAS there, but it conflicted with their well established views, call them political or not - it doesn't matter.

it would take a great deal of hubris to say 'yes, all other sciences and research suffer from the human condition, but not physics!'

Re: A Physicist Who Denies Dark Matter

#150

Post by boomboomsubban »

kradem wrote: post #146
boomboomsubban wrote: post #138

Earlier quoted context omitted.

It's not your English, I understand what you are saying, you're game of logic is using an old copy of the rules. Science doesn't dismiss things. Theories about ether were put aside when we started getting experimental results that it could not support and developed other models that explained it better. The theory still exists, and there is a possibility that someone will use it to better explain things in the future…

Thank you very much for your effort here in explaining things. There's nothing here in the thread powered by "my logic". I'm just certain that dark matter, ether, the Holy Grail, or anything, could be abandoned in our minds once we find the prettier chick to cope with, no matter how well we understood the previous one.

Yes, we could abandon it. The point of science is that we never should.

Before the scientific method was adopted, we would take that pretty woman, ignore any flaws, and make them essentially god. A new one had almost no chance to compete, even of they were much prettier.

With the scientific method, we say that she's the best around, but there's probably a better one out there, and with a little work it might be the old one. So it's easier to adopt new ideas, and the old ones still provide some value.

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