4 ms·

This is incorrect. Yes, Dark Matter is matter that does not emit light but it does not absorb nor reflect light as well. In other words, it does not interact wi

This is incorrect. Yes, Dark Matter is matter that does not emit light but it does not absorb nor reflect light as well. In other words, it does not interact with the electromagnetic force. That makes it extremely exotic. And, no, the Earth is not made of dark matter.

changoplatanero 5y ago
missed opportunity to call it stealth matter instead of dark matter
at_a_remove 5y ago
That's a rather newer definition. The concept has been around longer than the name, which is why I mentioned Neptune. The original definition was literally anything where the presence is puzzled out from its gravitational attraction instead of than its luminosity. Hence why MACHOs (MAssive Compact Halo Objects) were under consideration for being dark matter. They would consist of brown dwarfs, planets, and the like. They are currently out of vogue for not supplying enough gravitation, but that matter had no special properties to it. Not exotic at all. You can look this up. I sort of feel the frustration here of people on Wikipedia trying to correct something they actually know about.
- kbelder 5y ago
  It's interesting the way language works, and specifically naming. It's almost magic. There's various places where gravitational effects don't seem to line up with the distribution of mass that we see or expect. Something is generating gravity, that we can't see, in places we didn't expect. Call it 'dark' matter, because it's not shiny. But now that it has a name, it's treated a bit like a proper noun. Dark Matter. We do some observations that probably rule out simple nonluminous planetoids or dark stars. Whatever is causing the galactic rotation discrepancies doesn't seem to be normal matter. That translates into: 'Dark Matter' isn't normal matter. As if it is a certain thing, and not a reference to an unknown set. By naming it, and talking about it, even though we don't understand it, we run the risk of attaching all sorts of presumptions to its identity. We're prematurely normalizing a certain way of thinking about it. We may have done a similar thing to quantum mechanics. (I may not be making much sense here, it's just a thought that struck me and I'm working through it.)

changoplatanero 5y ago

missed opportunity to call it stealth matter instead of dark matter

at_a_remove 5y ago

That's a rather newer definition. The concept has been around longer than the name, which is why I mentioned Neptune. The original definition was literally anything where the presence is puzzled out from its gravitational attraction instead of than its luminosity. Hence why MACHOs (MAssive Compact Halo Objects) were under consideration for being dark matter. They would consist of brown dwarfs, planets, and the like. They are currently out of vogue for not supplying enough gravitation, but that matter had no special properties to it. Not exotic at all. You can look this up. I sort of feel the frustration here of people on Wikipedia trying to correct something they actually know about.

kbelder 5y ago
It's interesting the way language works, and specifically naming. It's almost magic. There's various places where gravitational effects don't seem to line up with the distribution of mass that we see or expect. Something is generating gravity, that we can't see, in places we didn't expect. Call it 'dark' matter, because it's not shiny. But now that it has a name, it's treated a bit like a proper noun. Dark Matter. We do some observations that probably rule out simple nonluminous planetoids or dark stars. Whatever is causing the galactic rotation discrepancies doesn't seem to be normal matter. That translates into: 'Dark Matter' isn't normal matter. As if it is a certain thing, and not a reference to an unknown set. By naming it, and talking about it, even though we don't understand it, we run the risk of attaching all sorts of presumptions to its identity. We're prematurely normalizing a certain way of thinking about it. We may have done a similar thing to quantum mechanics. (I may not be making much sense here, it's just a thought that struck me and I'm working through it.)