A Physicist Who Denies That Dark Matter Exists

Re:A Physicist Who Denies That Dark Matter Exists by XorNot on Monday February 27, 2017 @12:27PM (#13745927)

Because it would collide with itself. Dark matter isn't just "not visible" - it's non-electromagnetic. As observed it didn't aggregate when colliding with itself, so there aren't big dark matter made black holes around, nor gravity anomalies from dark matter nebula or the like.

Two dark matter particles headed directly at each other would pass through each other and be only slightly deflected by their gravitational interaction.

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Re:A Physicist Who Denies That Dark Matter Exists by btilly on Monday February 27, 2017 @07:36PM (#13750067)

Not necessarily. Dark matter could be made of small dense objects. Because they are small, we wouldn't see absorption of light. And because they are small, they will very seldom collide. These kinds of object are called MACHOs.

Based on observed dimming events while monitoring many stars, we have ruled out brown dwarfs as more than 20% of the total. Other possibilities still remain, but none have shown evidence of being sufficient to explain dark matter. However we have not ruled out the possibility of it being something that we haven't thought of yet.

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