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Our Weird Universe: Clumped Dark Matter
Growing up, I (like I assume many of you) had to memorize the steps in the scientific method. According to our classroom, science progresses by making hypotheses, designing careful experiments to test the hypotheses, and then analyzing the results and modifying the hypotheses as needed. I don’t know if science actually works that way in other fields, but that is seriously not how astronomy seems to work. Starting with Aristotle, theorists have built the theories, often without actually looking at the universe, and declared that we should be able to understand our universe from first principles, assumptions, and careful confirmation. Observers, including the likes of Galileo and Tycho Brahe, have then looked at the universe, said something along the lines of, “So sorry, reality doesn’t match your theory” and have demanded new theories, like Kepler’s equations of planetary motion. For a couple thousand years, astronomy has advanced, one or more unexpected observations at a time.
One of the simple assumptions about our universe that turned out to be utterly and totally wrong was that we can see with our telescopes all the sources of gravity. In 1933, just 4 years Hubble discovered the universe is expanding, Fritz Zwicky discovered that galaxies in clusters don’t orbit as expected, and there must be some invisible pull — some dark, unseen, matter, that is out there exerting a…
