4 ms·

There should be and we are looking for it. Several experiments are looking for WIMPs or other proposed particles on Earth or in the solar system. But the amoun

by maxnoe 7y ago

There should be and we are looking for it. Several experiments are looking for WIMPs or other proposed particles on Earth or in the solar system. But the amount us tiny, current estimates of the dark matter density in the Milky Way result in roughly 700 grams of DM in the Earths volume

adrianN 7y ago
Do we have estimates on how heavy individual dark matter "particles" are? Could the 700g all be in one blob?
wiz21c 7y ago
do you mean that 700g of that stuff can actually interact with earth's gravity in meaningful way ? If so, (I'm no scientist at all), that sounds like a very powerful matter indeed :-)
- maxnoe 7y ago
  700g are 700g. So no, the dark matter inside Earth has basically 0 effect on Earth.
  - d0mine 7y ago
    For comparison Earth mass is 5.9722×10^27 g. So yeah, the effect is basically zero.
girishso 7y ago
WIMPs?
DougWebb 7y ago
I've read (elsewhere, I guess) that some 95% of the Milky Way's mass is estimated to be dark matter. If there are only 700g of it nearby, it can't be distributed the same way normal matter is. How can that be, since it interacts with normal matter gravitationally? Does the solar wind blow it away, or something like that? I've also seen an article not long ago showing 'visualizations' of dark matter around a spiral galaxy, and it was mostly in teardrop-shaped lobes above and below the galaxy's center and aligned on the axis, rather than distributed through the disk. I didn't think of it at the time but now that I do, it seems like that distribution also indicates that light from the stars is pushing the dark matter away.
- cdumler 7y ago
  The reason why normal matter forms disks is because of electromagnetic repulsion: electromagnetic atoms naturally resist being in the same place as another atom. There becomes a tension between the repulsion to not stack up and gravity to compress things together. Since angular momentum is conserved, the matter will spin and flatten out: ie, a galaxy. If dark mater is a particle, it rarely interacts with anything, including itself; so, it cannot collapse. Most of the particles will be in a constant state of free fall throughout the galaxy. Only if the particle just happens to have a nearly matching velocity would it get trapped in a star or planet. Even then, it would still be wobbling around with nothing to touch.

by maxnoe 7y ago

adrianN 7y ago

Do we have estimates on how heavy individual dark matter "particles" are? Could the 700g all be in one blob?

wiz21c 7y ago

do you mean that 700g of that stuff can actually interact with earth's gravity in meaningful way ? If so, (I'm no scientist at all), that sounds like a very powerful matter indeed :-)

maxnoe 7y ago
700g are 700g. So no, the dark matter inside Earth has basically 0 effect on Earth.
- d0mine 7y ago
  For comparison Earth mass is 5.9722×10^27 g. So yeah, the effect is basically zero.

girishso 7y ago

WIMPs?

DougWebb 7y ago

I've read (elsewhere, I guess) that some 95% of the Milky Way's mass is estimated to be dark matter. If there are only 700g of it nearby, it can't be distributed the same way normal matter is. How can that be, since it interacts with normal matter gravitationally? Does the solar wind blow it away, or something like that? I've also seen an article not long ago showing 'visualizations' of dark matter around a spiral galaxy, and it was mostly in teardrop-shaped lobes above and below the galaxy's center and aligned on the axis, rather than distributed through the disk. I didn't think of it at the time but now that I do, it seems like that distribution also indicates that light from the stars is pushing the dark matter away.

cdumler 7y ago
The reason why normal matter forms disks is because of electromagnetic repulsion: electromagnetic atoms naturally resist being in the same place as another atom. There becomes a tension between the repulsion to not stack up and gravity to compress things together. Since angular momentum is conserved, the matter will spin and flatten out: ie, a galaxy. If dark mater is a particle, it rarely interacts with anything, including itself; so, it cannot collapse. Most of the particles will be in a constant state of free fall throughout the galaxy. Only if the particle just happens to have a nearly matching velocity would it get trapped in a star or planet. Even then, it would still be wobbling around with nothing to touch.