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