image: fdecomite
I'm not a nut, but I entertain at least one nutty idea. I can't imagine any way for my nutty idea to be tested (that hasn't stopped string theory), and I don't see why anyone would want to test my idea--it's nutty. But since it's April 1st, I'm throwing gravitas to the wind and posting my nutty idea. (Hey, I read yours.)
Here's how it goes.
Step 1: The rotational speeds of galaxies only make sense if they have much more mass than we can see--some kind of hidden material that is holding the disk together but doesn't radiate at any wavelength. This leaves cosmologists positing that a bizarre type of non-baryonic matter in fact makes up the vast majority of the universe.
Rather than accept that, a number of people are working on the idea of baryonic dark matter: normal stuff, but somehow rendered invisible. Black holes? Brown dwarves? Supermassive planets?
Step 2: Enrico Fermi famously wondered where everybody in the galaxy was. Stay with me here.
In short, the rapidity of life's appearance on Earth virtually as soon as the bombardment period ended some four billion years ago, and the rapidity of its evolution from blue-green algae up to the conscious entity reading this blog post, suggests that life is both ubiquitous and fast-evolving. The development of reflexive consciousness, tool use, and a disposition for territory expansion all seem like good candidates for trends that confer evolutionary advantage. Given the twelve billion year age of the Milky Way, what Nicolai Kardashev designated "Type 2 civilizations" should thus not only have come into existence (over and over again, in fact), they should have spread across the entire galaxy by now. Reasonable enough predictions have put the time required for complete colonization at between five and fifty million years, which is nothin' -- the former being only 0.05 percent the age of the galaxy.
So, Fermi and Frank Tipler and others asked, why don't we see them everywhere we look?
Step 3: In a 1959 paper in Science, Freeman Dyson speculated that the natural evolution of civilizations would be toward the development of energy-capturing shells that completely envelop their host stars - the famous "Dyson Sphere" (swarm, bubble, etc.).
Step 4: QED.
Get it? Fermi was right; Dyson was right. The hidden mass is in fact millions of stars whose radiant energy is completely occluded by Dyson sphere technology. 14.5 billion years is enough time for roughly 90% of the radiant energy in the universe to be sealed off by Type 2 civilizations, leaving the majority of the mass of any given galaxy only detectable by its gravitational effects.
Hey! The answer to the Dark Matter Riddle is the answer to the Fermi Paradox: We do, in fact, see advanced civilizations in every direction. Their activity can be inferred from the mismatch between the number of exposed stars and the obviously far greater galactic mass.
Okay, okay, I'll stop. But you heard it here first.
(Note: Actually, while I was composing this post "anonymous" beat me to the punch. In 10,000 years or so when our nutty idea is confirmed we will debate which of us was Darwin and which one Wallace.)