3 ms·
Excuse a layman's observation here. The dark matter problem rings as yet another mass-related anomaly we stumbled upon previously but on a nuclear scale. "Mas
by zoomablemind 8y ago
Excuse a layman's observation here.
The dark matter problem rings as yet another mass-related anomaly we stumbled upon previously but on a nuclear scale.
"Mass defect" [1], as appropriately named, is observed on a nuclear scale (whole nucleus mass is less than mass of nucleons that the nucleus is composed of). It is explained with binding energy required to keep the individual nucleons of a nucleus together.
That is an 'invisible' mass that gets subtracted from the 'free' mass of nuclear particles as measured.
Any possibility to project such analogy onto a galactic scale?
[1]: https://en.m.wikipedia.org/wiki/Mass_defect https://en.m.wikipedia.org/wiki/Mass_defect
- gus_massa 8y agoIn the Mass defect case, it's not an invisible mass what it is substracted. When some nuclei react to produce another nuclei, the energy of the mass defect is emitted as a gamma ray or as the energy of a fast electron/positron or something else. But all the mass can be found somewhere. It is only missing because you can't keep the gamma ray inside the balance. There should be a similar effect in a galaxy, because when the stars/gas/whatever get closer they have a small gravitational binding energy. I didn't do the calculations, but I'm sure it is so tiny (relatively) that you can safely ignore it. For comparison, in the Helium nuclei the difference is only 0.8%, in a galaxy it is (I think) abysmally smaller because the gravity is smaller than the strong force and the stars are much far away than the nucleons. But the dark matter is much bigger than the normal mater, something like x5 or x6. So it's not possible to explain the dark matter with a something that has a tiny effect.