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nixiebunny t1_iqtmx52 wrote

Reply to comment by Adrewmc in If objects in space are far away, does light get scattered enough that it would look “low resolution” by the time it reaches us? by hau2mk7pkmxmh3u

Yes, the interstellar medium (ISM) is rather opaque to visible light, but more transparent to infrared. My day job is in millimeter wave radio astronomy, which studies the makeup and behavior of the ISM.

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Ihavepurpleshoes t1_iqvbtqh wrote

What about dark matter? Can it block light or distort it?

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Skarr87 t1_iqvgy61 wrote

Whatever dark matter is, if it truly exists, appears to not interact with the electromagnetic field at all. This means that to light, dark matter doesn’t exist. So it would cause no change to any light passing through it. Dark matter does interact gravitationally so with enough of it one one place it can change the path of light causing a gravitationally lensing effect.

Fun fact, since it doesn’t interact with the EM field dark matter also can’t clump like normal matter does because you need those charge interactions to dissipate energy to slow down enough to clump. So dark matter just sort of oscillates back and forth through the center of gravity like a pendulum. This is why it always looks the same regardless of galaxy and why it’s always bigger than the galaxy.

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