I wonder if a higher dimension could also be the explanation for extra mass in the universe instead of dark matter. It's outside our perceptible space, but it still exists as mass, poking through into black holes or gently resting on the skin of our 3d volume.
The weird thing about it though is that whatever the dark matter is it has to be spread out. It couldn’t be little planets or brown dwarfs or burned out stars (in a hidden dimension or not) because we’d see more gravitational lensing events than we do
After digging a bit into astromy, computationally myself... There are some heavy assumptions used in the functions that maps pixels to mass densities. Outsider's 2c, but I assess a misalignment between CDM confidence in papers, and this mapping.
Interesting. It would be extraordinary if many of the discrepancies dark matter is required to explain are actually caused by some flaw in the data analysis. It seems unlikely, but not impossible.
I'm not familiar with the topic. Did you have any particularly suspect assumptions in mind?
I am overall suspicious of the degree of confidence used in papers in conjunction with the sheer number of assumptions regarding luminosity, the model of gas and stars in galaxies etc, vs what is discernible in the images (It's a low-resolution set of pixels). Of particular note is inferring mass (or lack thereof) that doesn't correspond to leading-edge luminosity. I.e. gas and stars that are away from the camera, and dim gas.
> The weird thing about it though is that whatever the dark matter is it has to be spread out.
In fact, they'd have to be so spread out that rotation curves remain flat past a million light years [1]. There seems to be no plausible particle dark matter distribution that can satisfy all of the necessary constraints at this point.
I thought dark matter was only observed through movements of matter within galaxies. Outer layers of spiral galaxies are observed to move faster than they should, so there has to be additional gravity and therefore mass that binds them on their (fast) orbits around the center.
Perhaps there is a negative gravity outside of galaxies where space seems to bubble out of nowhere anyway and the universe is expanding.
This seems as an attempt to combine gravity with the standard model again, which in my very amateurish understanding comes with multiple extra dimensions anyway. Isn't the higgs field basically a recently discovered additional dimension already? Among the other forms of particles that can be seen as an excitation of fields that compose these dimensions.
But for extreme cases like neutron stars or black holes, we probably do need to combine these theories since gravity is a main reason these objects exist in the first place. And also isn't a curvature of space not already be an additional dimension as well? It would be mathematically as I understand it.
