[olePigeon]

Dark Matter Exists | Cosmic Variance

Holy cow. This is one of the biggest days in cosmology. Actual proof of Dark Matter. This means that only about 5% of our known universe is made up of what we call normal matter! Whoa.

Anyway, Einstein's General Relativity doesn't work too well as you move out to encompase the entire universe. So now that we can directly observe Dark Matter and its interactions, we can develop new theories that will help refine General Relativity and our understanding of the universe.

I smell a Nobel Prize in Physics in the workings.

[hyteckit]

Originally Posted by olePigeon

Dark Matter Exists | Cosmic Variance

Holy cow. This is one of the biggest days in cosmology. Actual proof of Dark Matter. This means that only about 5% of our known universe is made up of what we call normal matter! Whoa.

Anyway, Einstein's General Relativity doesn't work too well as you move out to encompase the entire universe. So now that we can directly observe Dark Matter and its interactions, we can develop new theories that will help refine General Relativity and our understanding of the universe.

I smell a Nobel Prize in Physics in the workings.

What does this all mean? Normal Matter + Dark Matter = Doesn't Matter?

[Millennium]

That sound you heard was my head exploding as I read the article.

Not trying to say one way or the other whether or not I believe this, as I honestly have no clue. The article doesn't seem to do the best job of explaining this, however:

Originally Posted by TFA

This collision has done exactly what we want — it’s swept out the ordinary matter from the clusters, displacing it with respect to the dark matter (and the galaxies, which act as collisionless particles for these purposes).

I'm not sure I understand this: when I look at the pictures, it seems to me as though the dark matter is still overlapping with the ordinary matter. Am I missing something here?

[scaught]

it doesn't matter.

[olePigeon]

Originally Posted by Millennium

I'm not sure I understand this: when I look at the pictures, it seems to me as though the dark matter is still overlapping with the ordinary matter. Am I missing something here?

You're correct. Dark matter doesn't interract with normal matter, except possibly by weak forces, but it does interact with gravity.

[Kyros]

Originally Posted by olePigeon

You're correct. Dark matter doesn't interract with normal matter, except possibly by weak forces, but it does interact with gravity.

It's overlapping, but the collision separated its concentration enough from normal matter that gravitational lensing from even more distant galaxies focuses around the dark matter rather than the actual matter. It's like there's a flashlight off in the distance, and you have a device that can measure its shape. Between the flashlight at this device, there is a lens you can see and an invisible lens, but you aren't sure the invisible lens exists, you only theorize its existence. Because normally the lenses are basically directly on top of each other, you can't be sure it's really 2 lenses or if something else is going on. Then pretend something happens to separate the lenses. You can now see how the light is bent differently, and thus conclude that there are indeed 2 lenses. I hope that clarifies it a bit.

[olePigeon]

Originally Posted by Kyros

It's overlapping, but the collision separated its concentration enough from normal matter that gravitational lensing from even more distant galaxies focuses around the dark matter rather than the actual matter. It's like there's a flashlight off in the distance, and you have a device that can measure its shape. Between the flashlight at this device, there is a lens you can see and an invisible lens, but you aren't sure the invisible lens exists, you only theorize its existence. Because normally the lenses are basically directly on top of each other, you can't be sure it's really 2 lenses or if something else is going on. Then pretend something happens to separate the lenses. You can now see how the light is bent differently, and thus conclude that there are indeed 2 lenses. I hope that clarifies it a bit.

At that distance, light is bent by gravity so much that you get all sorts of optical anomalies. They had to rules those out, first.

[Kyros]

Originally Posted by olePigeon

At that distance, light is bent by gravity so much that you get all sorts of optical anomalies. They had to rules those out, first.

I do realize I explained in a simplistic way, that was the idea, after all.

[Dakar]

Originally Posted by Millennium

I'm not sure I understand this: when I look at the pictures, it seems to me as though the dark matter is still overlapping with the ordinary matter. Am I missing something here?

True, but if you look at the two pictures, the highest concentrations of dark matter appear to be in two circles at the horizontal thirds of the picture, while the ordinary matters appears to be concentrated at the center.

Two distinct locations.

[olePigeon]

Originally Posted by Kyros

I do realize I explained in a simplistic way, that was the idea, after all.

I was just elaborating for anyone else reading.