51–60 of 302 posts
Here comes the Alcubierre Warp Drive!
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…
Here's an argument: 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 tak…
https://en.wikipedia.org/wiki/Dirac_sea
Rather than have dark matter particles, have negative mass dark matter particles in every other location instead.
Sounds a lot like the concept of the Dirac sea to me. https://en.wikipedia.org/wiki/Dirac_sea Rather than have dark matter particles, have negative mass dark matter particles in every other location instead.
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…
Given there have been no detections of individual gravitons, saying it's a spin-2 gauge boson is speculation at best (though it might be what the model predicts)
https://en.wikipedia.org/wiki/Graviton mentions "[I]t can be shown that any massless spin-2 field would give rise to a force indistinguishable from gravitation, because a massless spin-2 field would couple to the stress–energy tensor in the same way that gravitational interactions do. This result suggests that, if a massless spin-2 particle is discovered, it must be the graviton." It links to other resources from there.
I'm curious about the idea of "allow[ing] negative masses to not only exist, but to be created continuously." Given the law (in the scientific sense) that matter/energy cannot be created or destroyed, on a scale of 1 to FTL travel, how crazy is this idea?
From the article:
"This is explained by the Hubble-Lemaître Law, the observation that more distant galaxies are moving away at a faster rate."
If we observe an accelerating universe how can be that galaxies in the past move away at a faster rate?
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?
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…
Um, correct my amateur understanding if it's wrong, but... we don't actually have a working quantum theory of gravity, do we? So how certain are we that gravity is mediated by a spin-2 gauge boson?