The Speculist

The Little Brown Universe

All kidding aside, this piece on brown dwarfs (for some reason I can't shake the non-sequitur that Professor Tolkien presumably would have called them "brown dwarves") is really interesting. I remember first reading about them years ago. We don't hear much about them, but they're fascinating. Consider:

Brown dwarfs are failed stars about the size of Jupiter, with a much larger mass -but not quite large enough to become stars. Like the sun and Jupiter, they are composed mainly of hydrogen gas, perhaps with swirling cloud belts. Unlike the sun, they have no internal energy source, and emit almost no visible light. Brown dwarfs are formed along with stars by the contraction of gases and dust in the interstellar medium, McLean said. The first brown dwarf was not discovered until 1995, yet McLean suspects the galaxy is teeming with them.

"Brown dwarfs are the missing link between gas giant planets like Jupiter and small stars like red dwarfs."

If large numbers of brown dwarfs exist, they "could make a small, but significant contribution to dark matter," the so-called "missing mass" in the universe, McLean said.

"Brown dwarfs won't account for all of the so-called dark matter," he said. "There is mass in the form of ordinary matter that is unaccounted for because we don't yet have the technology to find it. There are brown dwarfs, and maybe small black holes, and faint white dwarfs - regular stars that lost their outer gaseous envelopes leaving the burned-out core of old stars. White dwarfs, brown dwarfs, black holes, and gas account for some of the dark matter. The rest is presumably a new form of matter."

It's been said that astronomy is the second oldest profession. For the vast majority of human history, beginning when we lived in caves, astronomy has had to do with looking at shiny objects in the sky. In terms of human history, the notion that there's more out there that we can't see than we can is a novel one.

Brown dwarfs are now one of the suspects in The Case of the Missing Matter. They certainly raise some evocative images. What if, all along, there were as many invisible brown dots as there were twinkling white ones in the night sky? In fact, what if there were more of the brown dots? As a speculist, I'm devoted to the idea of parallel universes. Brown dwarfs provide a kind of convenient and economical parallel universe.

There could be trillions of these enormous cool worlds — or should we call them stars? — lying side-by-side with the universe we see. Suppose some form of life took hold on one of them and made its evolutionary way to intelligence. How fortunate these creatures would be if they decided to venture out into space. There's a whole universe of similar worlds out there for them to explore. So far, we can't say the same thing about our own planet. The brown-dwarfers might develop a vast intragalactic civilization, a galactic empire from which the bright stars and stony micro-planets that we think of as making up "the universe" would be viewed as an interstitial backwater. Pretty, perhaps, and even kind of mysterious, but having no real significance when weighed against the real universe.