Tuesday, September 20, 2011

The enigma of the Oort Cloud.

Today we’re going to do something a little different and talk about Science. Specifically the rather enigmatic theory of the Oort Cloud, which has had a cathedral of speculation built around it which rivals even Nebraska Man.

Let’s start with the basics. To quote Wikipedia: “The Oort Cloud is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun.”

Now, let’s be clear, here: no one has ever seen the Oort Cloud. Jan Hendrik Oort, who named it, never saw it. The hypothesis was created to explain where comets come from. We’re going to dig into a little bit more detail on that: long period comets(the ones that only pop up every few thousand years) have unstable orbits, thus dynamics dictates that they must eventually be ejected from the solar system or collide with the sun or a big fat planet(I’m looking at you, Jupiter.)

Then there’s the comet’s tail, the big long silvery thing that is what we typically associate with comets? That’s caused by the sun melting the ice the comet is made from. On each pass around the sun, the comet shrinks a little. So, in al old-earth model and the standard theory of solar evolution, the question is raised: why do we still have comets? If the sun is 4.5 billion years old, a comet with a period of, say, 5,000 years will have completed as many as 800,000 orbits. So either the comet was the size of a large planet, or it hasn’t been in orbit for that long.

Refusing to accept the idea that the sun could be any less than 4.5 billion years old, the Oort Cloud was proposed as a source of comets. That’s it, that’s the reasoning: we picked a number at random and said the solar system is that old, when physical observation didn’t agree, we made up the Oort Cloud to solve all of our problems. Keep in mind, these are problems that don’t exist in the much more reasonable young-earth model, but we won’t get into that right now.

As theories go, the Oort Cloud is about as flimsy as it gets. If it didn’t so neatly plug up the holes in so many other flimsy theories, it would be about as well-respected as the Flat Earth Society(yes, that is a thing, click the link.)

The list of theories that rest entirely on the existence of the Oort Cloud is mind-boggling! Everything from a super-Jupiter-sized planet to a freaking second sun use, as their basis, the existence of the Oort Cloud.

But here's where things start to get really trippy: those theories up there? They ALSO exist to explain away comets. It’s like a giant, overly-elaborate house of cards. Theory after theory, not supported by observation, all to help explain a phenomenon that is only a phenomenon when you look at it from the wrong perspective.

What happens when we finally disprove the existence of the Oort Cloud? The house comes tumbling down. But here’s the beautiful thing about the theory: you can’t disprove it. The Oort Cloud is too far away to reach and too dim to see with a telescope. We can’t send a spaceship out to survey it because it would take thousands of years to get there(Voyager 1 has been heading that direction for 35 years, it hasn’t even covered a 20th of the minimum hypothesized distance).

So proponents of the theory, and the people building other theories on it, are free to treat the Oort Cloud as fact, leaving the burden of proof to their detractors. How are we supposed to scientifically attack something that lacks any scientific defense?

And the true travesty in this instance is that the Oort Cloud is being taught as fact. In school textbooks, the word “theory” doesn’t even appear; kids are simply told “comets come from the Oort Cloud!” give it another few decades, and no one will even realize that it’s a theory at all. It will simply be accepted as fact.

What ever happened to the simplest explanation is most often the correct one?

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