It reads like a great example of how theory works.<p>You have some evidence (old planets), and a model that predicts it well (Newton/Kepler). Then some new evidence comes in (Uranus), and the theory is almost right, but not quite. So we modify it a little, or we start searching for an extra mass to explain the error.<p>Then some more experimental evidence comes in (galactic radial velocity), and we are thinking about modifying the theory a bit more (MOND). This is good for the radial velocity explanation, but not certain other things. We suppose there's some dark matter, and think about the consequences that would have. Then we see evidence consistent with that.<p>Of course this is a boiled down version. Real science is rarely so clean.
Sigh. Sure, it's possible, but very unlikely.<p>These "MOND" gravity theories purport to explain observations better than the theory of dark matter, but they don't. They explain some things and leave gaping holes elsewhere. On the whole they are hugely inferior theories in terms of matching observational evidence. Their only advantage is that they lack the existence of massive, weakly interacting particles, which a lot of people seem to have strong objections to despite the fact that several types of such particles are already known to exist.<p>Throughout the entire history of the development of the theory of dark matter the bias has always been against the idea of true dark matter, unseen particles that make up most of the mass of the Universe. But at every single step all of the other possibilities have been eliminated as realistic explanations of the evidence. The cold WIMP dark matter theory is the only one that explains the structure of the cosmic microwave background radiation, the large scale structure of the Universe, and the structure and behavior of galaxies and galaxy clusters. At this point the theory of dark matter is remarkably well hemmed in, it would be absolutely shocking to an extreme degree if it did not truly exist in the form we think it does.<p>There's additionally a very elegant mechanism behind the formation of dark matter. It seems most likely to be composed of super-symmetric particles. Such particles would only be able to form in extreme, high-energy conditions. Precisely the sort of conditions that existed in the early era of the Universe immediately after the Big Bang. So the early Universe would have been creating huge quantities of such particles, which would then not interact much due to their weak interactivity. It wouldn't be until the Universe had expanded enough and cooled down enough to halt their production. This would neatly explain why so much of the mass of the Universe is in the form of dark matter rather than conventional matter.
I graduated physics, but I'm almost a layman when it comes to general relativity. Still, I wonder if another possible explanation for stuff that don't match theory could be the basic assumption about our current cosmology. That the space is flat where there's no matter. Since there's a relation between the geometry of the space and the matter within, would it be unreasonable to believe that space itself could be curved independently of the matter we can observed? Maybe for other reasons, yet unknown?
Something has orbits around galaxies
failing to follow the law of gravity
from ordinary matter. The orbits
are as if there
there is some more mass with
gravity, mass that doesn't interact with
light.<p>Something is in/near galaxies is bending
light as if there were more mass there
than there is from just ordinary matter.<p>So, for that extra mass, call it <i>dark
matter</i>.<p>Seems simple enough.<p>"Flaw in the theory of gravity?" Maybe,
but that seems to be the hard way
to get an answer.
"your theory has <i>three</i> burdens to meet:"<p>...<p>"it must make new predictions that can be experimentally or observationally tested, and confirmed or refuted, that are unique to this new theory"<p>(<i>"MOND fails spectacularly, either offering no predictions..."</i>)<p>I fail to understand the necessity for <i>new</i> predictions. This simply may or may not come out of new theories as a paradigm shift consequence and it is therefore just optional, not a must. In fact, I fail to fully understand even the first requirement (about reproducing <i>all the successes</i> of previous leading theory) - the current leading theory's explanation may happen to explain things <i>somehow</i>, but that may not be necessarily correct. I wouldn't dismiss a competing theory even with holes in it if there is a slightest chance that further work on it or on something closely related to it may come to cover those shortcomings in time.
Interesting, I always thought of dark matter as just a lot of extra "dust", the dust that clumps to make the stars that make up the universe. The asteroid belt, the extra mass in our kuiper or oort clouds, etc. The dust that blocks parts of our view of the Milky way.<p>This article (and others I'm now skimming) point out that dark matter needs other magical properties however. Why is that the case? Why does simple "dark dust" not fit?
You can distribute dark matter in space to shape it in any pattern you like and give the dark matter any kind of property just to create a mathematical model that is consistent with observations.<p>Dark matter is just a theoretical concept - for now or forever.
Most of concepts we are conditioned to take for granted does not exist outside our head.)<p>The essence of scientific method is not in piling up concepts or in building up a support for a fancy theory. On the contrary, it is in exactly opposite - it is to refute and remove everything "mental" to see what remains, something which cannot be shaken by mere speculations or dismissed by any experience. That, perhaps, has something to do with what we call Truth.<p>According to the ancients, who practiced this method, there is nothing but different forms of light.<p>The question "what is between two Photons" makes no sense, because two Photons have nothing in common exept an imagination of an observer. Tracing them back "in time" makes no sense either, because time as a category is irrelevant to the light. It doesn't change.
I found the most interesting part of the article to be this image of a 1919 newspaper illustrating <i>"Starlight bent by the sun's attraction": The Einstein theory.</i><p><a href="https://d262ilb51hltx0.cloudfront.net/max/847/1*LV-wtp9IclSx2-SZuP1FsA.jpeg" rel="nofollow">https://d262ilb51hltx0.cloudfront.net/max/847/1*LV-wtp9IclSx...</a><p>As for the rest of the article, well, Betteridge's law holds, though with the "as best we know"-suffix implicit to science and science journalism.
Of course dark matter doesn't exist.<p>Hello, people. Dark matter is the eflourescent ether theory of the 21st century.<p>There are things that we don't know how to explain right now.<p>We have some ideas about how they can be explained. But they are really really bad.<p>We will be laughing at dark matter theory in a few years.
For those who are interested, physicist John Hartnett has developed a model that does not require dark matter. His work builds on that of Moshe Carmeli, who published "Cosmological Special Relativity". Hartnett's book is "Starlight, Time, and the New Physics" ISBN 978-0-949906-68-7. Disclaimer: I am not a physicist, and the math is way over my head, so I cannot double-check it. Hartnett has not made much, if any, headway with mainstream scientific publications, probably because he is a Biblical Creationist.
I'm no physicist but I've asked myself this question. It's a bit like string theory. String theory is a mathematical answer that solves some (all?) of the inconsistencies between quantum theory and gravity but has some implications that have no experimental evidence (eg extra dimensions).<p>Dark matter always struck me as a kludge to explain the universe fit our model. There are many theories on it but no observed or experimental effects of dark matter to date.<p>We say that there are four fundamental forces in the universe: weak nuclear, strong nuclear, electromagnetism and gravity. The first three are pretty adequately explained by quantum mechanics (AFAICT). The last of course isn't but is described pretty darn well by relativity.<p>Thing is, what's always struck me as odd is the other forces, I believe, can both attract and repel. There is no observation or experimental evidence of "antigravity".<p>It has always made me wonder if we're not making an error by trying to fit gravity into the Standard Model. Perhaps it's not a force like the others are and simply the result of the nature of space-time.<p>Anyway, like I said: complete layman here. What I'm saying might be completely nonsensical to anyone with half a clue about physics.<p>I know the LHC has looked and is looking for any evidence at the edges of the Standard Model of some violation that will hint at something that might explain all this. I also know minds far brighter than mine have spent a lot of time thinking about this.<p>I'm still left wondering if dark matter/energy isn't simply another "string theory".