M. M. One of your most famous theories is about dark matter. Can you explain what it is about?
L. R.
Dark matter is matter that is a lot like the stuff we know except that it doesn’ t interact with light. We know about its existence because of its gravitational influence on the galaxy and the universe. In our galaxy, we know that although ordinary matter sits in a disk, dark matter surrounds it in a spherical halo.
In principle, dark matter could have non-gravitational interactions as well. However, so far there has been no evidence of such interactions. In fact, the strength of dark matter interactions is very constrained. If dark matter interactions were bigger, the halo shape would not agree with observations. Furthermore, observations of the Bullet Cluster clearly indicate that
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photo: NASA
M. M. One of your most famous theories is about dark matter. Can you explain what it is about?
L. R.
Dark matter is matter that is a lot like the stuff we know except that it doesn’ t interact with light. We know about its existence because of its gravitational influence on the galaxy and the universe. In our galaxy, we know that although ordinary matter sits in a disk, dark matter surrounds it in a spherical halo.
In principle, dark matter could have non-gravitational interactions as well. However, so far there has been no evidence of such interactions. In fact, the strength of dark matter interactions is very constrained. If dark matter interactions were bigger, the halo shape would not agree with observations. Furthermore, observations of the Bullet Cluster clearly indicate that