Here are some interesting features of dark matter that are currently known:
Remarkably, our inability to see or detect dark matter provides clues as to how it behaves. It must have few interactions with itself and conventional matter apart from the force of gravity – otherwise we would have detected it emitting light and interacting with other particles. As dark matter mostly interacts via gravity alone, it has some curious properties. A cloud of hot gas in space can lose energy by emitting light, and thus cool down. A sufficiently massive and cold gas cloud can collapse under its own gravity to form stars. By contrast, dark matter cannot lose energy by emitting light. Thus, while conventional matter can collapse into dense objects like stars and planets, dark matter remains more diffuse. This explains an apparent contradiction. While dark matter may dominate the mass of the universe, we don’t think there is much of it in our Solar System. …
Most astronomers would say dark matter is the simplest and best explanation for many of the phenomena we see in the universe. While there are potential issues for simplest dark matter models, such as the number of small satellite galaxies, they are interesting problems rather than compelling flaws.
But the fact remains that we are yet to detect dark matter directly. This doesn’t particularly bother me, as physics has a history of particles that have taken decades to directly detect. If we haven’t detected it 20 years from now I may be concerned, but for now I’m betting that dark matter is the real deal.
Michael J. I. Brown, “Why do astronomers believe in dark matter?” at The Conversation
Is dark matter the Higgs boson, hard to find but eventually found, or the ether, once believed to pervade the universe? If twenty years pass with no dark matter, unfortunately, the needle will tilt a bit more toward the ether.
Discover: Even the best dark matter theories are crumbling
Researcher: The search for dark matter has become a “quagmire of confirmation bias” So many research areas in science today are hitting hard barriers that it is reasonable to think that we are missing something.
Physicists devise test to find out if dark matter really exists
Largest particle detector draws a blank on dark matter
What if dark matter just doesn’t stick to the rules?
A proposed dark matter solution makes gravity an illusion
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Proposed dark matter solution: “Gravity is not a fundamental governance of our universe, but a reaction to the makeup of a given environment.”
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