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Comment Re:Dark matter does not exist. (Score 1) 156

I did read what you wrote. If you had read the Wikipedia article you would know that
1) The evidence that dark matter is actually a new physical thing is overwhelming.
2) The evidence is not only "interactions between galaxies".
3) The theory does not allow for other causes of the interaction.
4) Everyone that works with it does use the name dark matter for the proposed particles (such as WIMPs, axions, or sterile neutrinos).

Comment Re:Not exactly direct evidence (Score 1) 156

That is an extremely complicated theory. Your "God" concept is not even well-defined. The best attempts to do it involve books with hundreds of pages, that are nevertheless full of contradictions.

Particles evolving under the laws of General Relativity, on the other hand, can be described in a few pages. The universe doesn't care about whether your primate brain understands it. There exists an objective measure of complexity - Kolmogorov complexity - and this is what science cares about.

Comment Re:Not against dark matter (Score 5, Interesting) 156

I have a PhD in theoretical physics. Not in cosmology, but I have some contact with people who do work on it.

So, 2) is astronomically unlikely. The experimental evidence comes from multiple independent sources spanning decades. It consists of simple things such as measuring the rotational speed of galaxies and more sophisticated measurements such as anisotropies in the cosmic microwave background. If you are willing to doubt this kind of evidence you might as well doubt GR itself.

As for 3), everyone and his dog likes to propose modified theories of gravity that would do away with dark matter. The problem is that reconciling them with the mountain of evidence for dark matter is really tough. The most popular candidates, MOND and entropic gravity are far from being able to do it. Until they do, we're stuck with 1).

Comment Re:Not exactly direct evidence (Score 2) 156

If we would go with "weird" as a criterion to discard theories, we wouldn't have quantum mechanics. Or relativity. Or electromagnetism. Or almost anything that goes beyond our day-to-day experience.

Of course, one needs a lot of evidence to accept a new kind of matter, as it does require changes to our fundamental theories. We do have such evidence, and we don't have any other theory that can explain it.

Comment Re:Not exactly direct evidence (Score 2) 156

Well, that is indeed the gold standard of theory falsification, but I think is not strictly necessary. If I have a theory that is both simple and consistent with all available data that theory is good enough for me.

But this is a bit beside the point, as we have the famous Baryon acoustic oscillations, which were predicted by cosmological models with dark matter, and then observed by WMAP and SDSS.

Comment Re:misleading nonsense about fantasy matter (Score 1) 156

While I agree with the spirit of your post, I think your description of Dark Energy is inaccurate. It is not simply the accelerated expansion of the universe, but more precisely explaining this accelerated expansion through a nonzero cosmological constant. While alternative explanations are considered implausible by the cosmologists, they are far from being inconceivable.

Comment Re:Not exactly direct evidence (Score 1) 156

I don't think there is something wrong with postulating stuff to make our observations match our predictions. This is how science advances. Try explaining the observations of particle accelerators without postulating the existence of quarks, electrons, protons, neutrons, or atoms for that matter.

The real criterion is whether the stuff you postulate has simple properties or it behaves like fairy dust, magically explaining everything by having several arbitrary properties. I think dark matter falls clearly in the former category, as it can interact only through gravity, greatly restricting what it can do.

Also, obligatory XKCD.

Comment Re:Because it is profitable to do so (Score 1) 575

Meanwhile, in the civilized world, it is just plain illegal to drag someone out of a plane they have already boarded.

If some European company, in a fit of insanity, tries to call the police to get someone removed from a plane because they want the seat (as opposed to the passenger threatening others and so on) the police would just say no. And probably arrest the airline exec if they make too much of a fuss.

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