What spatial scales does dark matter become significant?

[Albertgauss]

Hello,

How much volume or mass of space does one need to see appreciable effects of dark matter where general relatively seems to break down? What is the critical volume of space at this time where people can see the effects of dark matter and where they cannot? Is there a spatial scale smaller than galaxies--or even sub-sections of galaxies--where the effects of dark matter first manifest themselves as departures from general relativity?

 

[mfb]

How much volume or mass of space does one need to see appreciable effects of dark matter

Small galaxies and similar structures. Star clusters are usually too small, but there are exceptions.

where general relatively seems to break down?

It doesn't.

 

[NFuller]

How much volume or mass of space does one need to see appreciable effects of dark matter where general relatively seems to break down?

If dark matter exists then GR is not breaking down. There is just extra mass that needs to be taken into account.

What is the critical volume of space at this time where people can see the effects of dark matter and where they cannot?

I think that would technically depend on how accurately you can measure the motions of bodies in space. Dark matter is often considered important when studying large sections of galaxies and anything larger. I am not aware of any precise number for the scales at which dark matter should be considered.

 

[Albertgauss]

Okay, sounds good. I just wanted to get a basic idea. Yes, yes about GR not breaking down, I realize I worded that wrong.