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There are alternative explanations that theorized that the 2nd law is not linear for extremely weak forces.[1] Thus, two masses that were sufficiently far apart would experience an attraction larger than that predicted by an inverse square law.
I think some particular applications of these theories were proved wrong some years ago, but I can't find those results.
[1] https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics
Every " dark " physics piece is essentially a science opinion piece, with " darkness " included in the title as the general prevailing clickbait advertising strategy, because the layperson interpretation is that it implies sinister mysteriousness. It's never news, it's just a refresher listing of unknowns.
The word 'dark' is used in titles because the articles are about the nature of dark matter and dark energy, which are widely accepted terms. You would have to go out of your way not to use the word dark when talking about these subjects and it would make titles less descriptive.
That assumes that inertial mass = gravitational mass, which is assumed to be true, not not proven.
Earlier quoted context omitted.
To clarify (presuming I understand correctly): Antimatter might have negative gravity, but dark matter can't be antimatter, because we'd see the gamma rays from the collisions.
But if they’re repelling each other and for billions Of years. Why should there be any collisions?
The possibilities for Star Wars puns are endless. There are alternative explanations that theorized that the 2nd law is not linear for extremely weak forces.[1] Thus, two masses that were sufficiently far apart would experience an attraction larger than that predicted by an inverse square law. I think some particular applications of these theories were proved wrong some years ago, but I can't find those results. [1]…
https://en.wikipedia.org/wiki/The_Immunity_Syndrome_(Star_Tr...
A "dark fluid" with negative mass COULD dominate the Universe, sure. But so could galactic-scale electric currents and magnetic fields, and is more likely. No one ever talks about that.
Gravity is a product of this also.
Light is a circuit
and black holes don't exist
Earlier quoted context omitted.
"Every other force besides gravity is polarised, so why not also gravity?" Gravity is mediated by a spin-2 gauge boson, the graviton, whereas the other known fundamental forces are mediated by vector (spin-1) bosons. There is an exercise in Peskin & Schroeder (I believe) working out the lack of a gravitation "repulsion" resulting from this difference. That being said, I think this kind of phenomenology is excellent a…
My understanding is that the entire existence of the graviton is still theoretical. Has that changed recently?
Paper: https://arxiv.org/pdf/1712.07962.pdf Not a physicist, but my summary of the author's point would be: If you allow for matter with a negative mass and plug it into a n-body simulation. You seem to get what looks like dark matter from first principles. Namely, a halo of non interacting matter around galaxies in just the right "non-cuspy" shape. Their conclusion is that this is worth considering, as almost all ma…
If you think about it, "mass" actually means two different things. One one hand, there is mass as the "charge" of gravitational interaction, that is, the gravitational field generated by a body is proportional to its mass. Let's call this concept "gravitational mass". On the other hand, you have mass in the sense of "intertial mass", a body's resistance to change of velocity. Although we kinda take it for granted, it's weird that these two concepts coincide, and not something that would be necessarily true a priori.
Asserting this equivalence as a principle is the starting point for Einstein's theory of General Relativity, which is one of the most beautiful and thoroughly tested theories in modern physics.
On the other hand, you can show that the inertial mass cannot be negative (else the Lagrangian would not be bounded from below and therefore you could not minimise it; the whole of physics then comes crumbling down). Therefore, if that equivalence stands, the gravitational mass also cannot be negative.