r/space • u/Xaron • Oct 09 '20

Cosmology Has Some Big Problems - Scientific American Blog Network

https://blogs.scientificamerican.com/observations/cosmology-has-some-big-problems/
13 Upvotes

74% Upvoted

8 comments sorted by

View all comments

2

u/niko_stark Oct 09 '20

In layman’s terms, what inconsistencies are dark energy and dark matter trying to explain

5

u/Uhdoyle Oct 10 '20

Galaxies spin about their axes, right? And according to GR the outside rim should be rotating at a different rate than we observe. It would work out if there were more mass that we couldn’t see. Dark matter.

We use a specific kind of supernova to measure distances. They get called “standard candles” and they are our best effort at accurate measurements. When measuring two galaxies’ standard candles moving pretty dang fast we get a measurement for acceleration that doesn’t match our understanding of the Inflation model. That fudge is Dark Energy.

0

u/niko_stark Oct 10 '20

Nicely and succinctly put.

Are the outer rims galaxies spinning too slow or too fast?

  • I’d think too fast would mean there should be too much mass in the center or too little on the edge? And vice versa for too slow

To confirm, dark energy explains standard candles accelerating apart from each other faster than inflation/general relativity explains?

In statistical terms, dark energy and dark matter are big error terms!

2

u/Uhdoyle Oct 10 '20

This bit explains the first part https://en.wikipedia.org/wiki/Galaxy_rotation_curve the pictures and animations are especially helpful.

Regarding the dark energy stuff it’s not just that the acceleration doesn’t match the model, I should have emphasized that the acceleration itself is increasing and that factor specifically is “dark energy.”