5 ms·

Funny thing about the missing mass. Papers will say "this could be explained by a dark matter Halo with this distibution". They assume it gravitationally affect

Funny thing about the missing mass. Papers will say "this could be explained by a dark matter Halo with this distibution". They assume it gravitationally affects regular matter the same way regular matter does. What is usually missing is 1) how dark matter interacts with dark matter 2) why it should have this particular distribution - dynamic model. Without those things, the explanation is IMHO worse than MOND because it doesnt make sense that some matter would end up with a completely different distribution. Oh and we cant actually detect it directly either, but trust us it must be there.

gliptic 4y ago
This is not actually missing from the models. See for instance https://www.nature.com/articles/s41550-021-01598-4 https://www.nature.com/articles/s41550-021-01598-4
ncmncm 4y ago
There is no reason for matter with very different interaction properties from the familiar stuff to have the same distribution. In particular, familiar stuff has ways to dispose of kinetic energy, allowing it to clump into our stars and planets, that might be unavailable to putative dark matter, making any dark matter more diffuse. Generally, you can start with the assumption that people working on dark matter hypotheses are not idiots. They might still be wrong, but if they are, they will be wrong in interesting and subtle ways, not obvious ones.
- phkahler 4y ago
  >> There is no reason for matter with very different interaction properties from the familiar stuff to have the same distribution. Sure there is. It has similar interaction with regular matter. Any other properties need to be defined and shown to produce this claimed distribution as a result of a dynamic process. Anything less and we can just say dark matter is fairy dust.
  - ncmncm 4y ago
    "different interaction" != "similar interaction". Apparent effort to understand what you criticize may make your criticism seem worth more.
- phkahler 4y ago
  >> Generally, you can start with the assumption that people working on dark matter hypotheses are not idiots. Actually no I cant. When someone looks at galaxy rotation curves and is surprised they dont follow keplers laws, it activates the bozo bit in my mind.
  - ncmncm 4y ago
    Are there others?

gliptic 4y ago

This is not actually missing from the models. See for instance https://www.nature.com/articles/s41550-021-01598-4 https://www.nature.com/articles/s41550-021-01598-4

ncmncm 4y ago

There is no reason for matter with very different interaction properties from the familiar stuff to have the same distribution. In particular, familiar stuff has ways to dispose of kinetic energy, allowing it to clump into our stars and planets, that might be unavailable to putative dark matter, making any dark matter more diffuse. Generally, you can start with the assumption that people working on dark matter hypotheses are not idiots. They might still be wrong, but if they are, they will be wrong in interesting and subtle ways, not obvious ones.

phkahler 4y ago
>> There is no reason for matter with very different interaction properties from the familiar stuff to have the same distribution. Sure there is. It has similar interaction with regular matter. Any other properties need to be defined and shown to produce this claimed distribution as a result of a dynamic process. Anything less and we can just say dark matter is fairy dust.
- ncmncm 4y ago
  "different interaction" != "similar interaction". Apparent effort to understand what you criticize may make your criticism seem worth more.
phkahler 4y ago
>> Generally, you can start with the assumption that people working on dark matter hypotheses are not idiots. Actually no I cant. When someone looks at galaxy rotation curves and is surprised they dont follow keplers laws, it activates the bozo bit in my mind.
- ncmncm 4y ago
  Are there others?