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This is a weak assumption IMO. It is also possible that the stars "just" have a common origin and move at similar enough trajectories without being gravitationally bound.
> All three stars are co-moving with similar chemistry, which implies they are bound ... I am not an orbital mechanic, but the word "chemistry" is jarring to me here. Is it just a strained metaphor or is there some sense it which it fits? Maybe the romantic chemistry of mutually attracting bodies?
I think they mean "chemical composition", e.g. how much hydrogen / helium / other elements there are in the star, deduced from their spectra
Not a physicist, but I never heard of this before and looks quite interesting at first glance. Google indicates that mainstream physics regards it sceptically ("pseudoscience"), but it was difficult for me to find out why . I found a single paper containing criticism from an actual physicist ("A sceptical analysis of quantized inertia" by Michele Renda: https://academic.oup.com/mnras/article/489/1/881/5545603 ), but…
The main reason, as far as I'm aware, is because McCulloch then went on to claim to invent several thrusters (EmDrive, most notably) derived from the effect that break normal conservation of momentum.
Earlier quoted context omitted.
I think they mean "chemical composition", e.g. how much hydrogen / helium / other elements there are in the star, deduced from their spectra
What could the chemical composition of the planets have to do with observations of their inertia? How could that matter other than by their mass?
Only read the first few pages, but as a non-physicist, but who went through grad school, it appears the author is advertising their own prior work quite a bit. I generally associate this behavior with a) cranks b) stubborn people who lost an ideological turf battle
Not only that, but it's prior work that is based on a false premise. The author's proposed "solution" is based on Unruh radiation, but Unruh radiation is zero for an object in a free-fall orbit. To get nonzero Unruh radiation, you need proper acceleration, i.e., some non-gravitational force has to be acting on the object. Unless the author is claiming that Proxima Centauri has a rocket attached to it, his model fails at step one. I believe other physicists have pointed this out but the author prefers not to mention or address this criticism.
Not a physicist, but I never heard of this before and looks quite interesting at first glance. Google indicates that mainstream physics regards it sceptically ("pseudoscience"), but it was difficult for me to find out why . I found a single paper containing criticism from an actual physicist ("A sceptical analysis of quantized inertia" by Michele Renda: https://academic.oup.com/mnras/article/489/1/881/5545603 ), but…
So, not a physicist, but the claims in the PDF about how GR has "never predicted a single galaxy rotation curve" are overblown, right? Aren't there a handful of galaxies where the rotation curve lines up pretty close with the predictions from the visible mass? Any new physics has to explain those, too. Anyway, I think I can see why QI is so appealing. The paper contains a very short and sweet explanation.
As the saying goes, all complex questions have simple, easy to understand wrong answers. This is an example. See my response to georgeburdell upthread.
As for galaxy rotation curves, yes, the paper's claim is overblown.
Earlier quoted context omitted.
Because it's a conspiratorial mindset that willfully ignores the long list of other evidence for dark matter in favor of mocking physicists who are doing their best to make sense of confusing observations. That's exactly the kind of thing that downvotes are meant for.
I see zero evidence for any of that. Science has a long history of proposals based on various fudge factors. Some of those fudge factors disappear when we get better measurements. Some require learning more about the system. For example Newton's theory of sound was consistently wrong until Laplace figured out how adiabatic heating changed things. Some require learning more about the physics. For example Einstein got…
There are many dark matter theories that address these problems, and we can talk specifics about each one and how it addresses each of the dark matter problems.
Earlier quoted context omitted.
I see zero evidence for any of that. Science has a long history of proposals based on various fudge factors. Some of those fudge factors disappear when we get better measurements. Some require learning more about the system. For example Newton's theory of sound was consistently wrong until Laplace figured out how adiabatic heating changed things. Some require learning more about the physics. For example Einstein got…
If you don't see the mocking tone of the comment we're talking about, and you don't see the conspiratorial tone of the anti-dark-matter crowd in general, then yeah, you won't see why they're worthy of downvotes. But then we live in different worlds, so I guess there's not much to discuss.
The truth is this. Dark matter is observationally the best theory that we've got. However it is deeply unsatisfying. It requires fundamentally new physics about fundamentally new stuff with properties that we have absolutely no clue about. It is literally a theory of, "Insert magic cosmic glue here."
Virtually any idea can be inserted. String theory is popular despite having made a single verifiable prediction in decades of trying. So let's say that dark matter is made of strings!
Maybe if the Everett interpretation were more popular we'd theorize that a proper unified theory will have a small gravitational interaction between quantum superpositions. So what looks like dark matter is really the gravitational interaction with the superpositions of the stars in the galaxy that have been evolving since the early universe. Thanks to the fact that multibody gravity systems are chaotic, every tiny variation grows over time until those superpositions just act like a smooth smear, which we can't directly perceive because of quantum decoherence. Is this a reasonable theory? Don't ask me, I just made it up. But I know that it doesn't require any new kind of matter - it just requires a bit of speculation about interpretations of QM and the nature of quantum gravity. And it would look just like dark matter does.
The truth is that we've got a theory, and we know how to fit the data to it. But that theory doesn't integrate well with all of our other theories. Therefore, no matter how well we've made the facts fit, intellectual integrity requires that we remain open to the idea of being wrong. Not so open that we stop pursuing what *WE* think is right. But open enough to recognize that other people's discomfort with the theory is actually somewhat reasonable. No matter how strongly we might think that it is right.
Earlier quoted context omitted.
I see zero evidence for any of that. Science has a long history of proposals based on various fudge factors. Some of those fudge factors disappear when we get better measurements. Some require learning more about the system. For example Newton's theory of sound was consistently wrong until Laplace figured out how adiabatic heating changed things. Some require learning more about the physics. For example Einstein got…
If we're going to get technical, then the source of confusion here is that the term "dark matter" is considered a theory by lay people. Whereas scientists view dark matter as a set of outstanding problems in cosmology. There are many dark matter theories that address these problems, and we can talk specifics about each one and how it addresses each of the dark matter problems.
On the other hand, squint at pretty much any theory, and you can see a series of related theories. That are each the basic theory, plus another assumption or two about another thing that might be observed. Leading to a cascade of differences that result in distinct theories.
Therefore dark matter can be a theory, and there can also be many theories of dark matter. Just like evolution can be a theory, and there can also be many theories about how exactly evolution progresses. Exactly what we call a "theory" here becomes rather arbitrary.