Lecture 21: Geometry of the Universe

[RJN]

The lecture video is embedded below but also available here in MP4 format.
Additionally, slides used in the lecture are embedded below but also are available here in Powerpoint format.
Questions after the lecture? Please ask them in here.

Click to play embedded YouTube video.

Wikipedia entries:

• Shape of the universe
  Redshift
  Dark matter
  Dark energy
  Age of the universe

[Graeme1858]

Hello

I have just watched Lecture 21, brilliant!

At about 16 minutes there is a slide on the Bullet Cluster and you use the phrase " the dark matter can be seen" and is shown in blue, separate from the red gas clouds.

Could you clarify please, I understand the requirement for an even spread of mass for the gravitational lens to work smoothly but is the blue a false colour image or does the dark matter cause the gas to appear blue?

Thanks

Regards

Graeme

[geckzilla]

At about 16 minutes there is a slide on the Bullet Cluster and you use the phrase " the dark matter can be seen" and is shown in blue, separate from the red gas clouds.

Could you clarify please, I understand the requirement for an even spread of mass for the gravitational lens to work smoothly but is the blue a false colour image or does the dark matter cause the gas to appear blue?

The blue represents where dark matter is inferred to exist based on how much mass would actually need to be there for the gravitational lens to happen. So yes, it's false-color. In fact the blue part is entirely generated based upon known assumptions.

[Graeme1858]

Cheers Geck

Thanks for the clarification.

Regards

Graeme