Tuesday, June 17, 2008

Our Insane Universe

Our universe managers all kinds of complex structures with just a few simple rules, many of them actually fairly intuitive once grasped. Take, for instance, gravity. Even the ancient human tribes noticed that when you drop things, they fall down. Newton refined this by noting that since the earth was round, the motion of the moon around it could be understood as both flying forward and being yanked down, which would combine into a vaguely circular orbit, the kind the moon actually has.

Gravity works as:
Gravity formula thanks to Cairnavaron and TinyPic

That is, acceleration due to gravity is the mass of the first thing times the mass of the second thing, divided by the distance between the two squared, all multiplied by a really tiny constant, G.

So gravity increases by the size of the objects involved, but decreases if the distance between the two increases.

This fairly simple rule does everything from falling apples on earth, to orbits in the solar system, to the formation of galaxies.

But some of these rules are quite...odd.

For one, if you have two sheets of metal near each other, in a vacuum, they pull towards each other. This got named the Casimir effect, after the scientist who first discovered it. Could you make power from it? Only if you had some way of repeatedly pulling the plates apart afterwards. Other rules are even wierder.

Take the rule of virtual particles. In a vacuum, that is, a space with nothing in it, you would expect there to be no activity, right? Wrong. In 1935, it was proposed that constantly, all the time, a particle and its opposite borrow the energy for each other's existence from nothing, fly apart for a bit, and then strike each other, which destroys both and returns the borrowed energy. This sounds patently insane.

And yet MIT claims to have proof of this state of events. In fact, Steven Hawking found the first proof of this with black holes. He said that near enough to a black hole, one of the particles would be sucked into the hole, leaving the other one to fly off into the universe. This would create a stream of particles from the black hole, coming from two readily found poles. Radio astronomers later verified that this does, indeed, happen.

The physics of the very small, Quantum physics, is full of this kind of patent madness. The term "quantum" comes from Latin, meaning "How much?" Much of the problems are due to the small scales involved.

For instance, observing things at this scale changes them. This may not be terribly intuitive at our scale, but it does make sense. Let's say you could somehow shine a light on quantum events and see them. The light would impart energy to these particles simply by touching them. (There are two theories of light, in the corpuscular theory, light is like a solid BB, and the collision with the light would push the particle away from the light. In wave theory, light waves are absorbed by the particle, which, yes, pushes the particle away from the light. Again consistent with the insanity theme of this entry, both theories have seen proof, which doesn't make sense.) Because of this measurement problem, you cannot know both the position and velocity of a particle, because the only way of finding out one totally changes the other. This makes it hard to talk about specifics.

In the very small scale, particles can teleport short distances. That is, they somehow move between point A and point B without going through the space between the two. Supposedly, particles could teleport as far as they like, but the more distant the teleportation, the less likely it is to actually happen. A teleport of a nanometer is quite common, a centimeter incredibly rare, a meter less likely to happen than you winning every lottery in your country, and a kilometer rarer than a suitcase full of gold bullion spontaneously appearing in your hand. (Which could, under virtual particle theory, happen, but probably won't for the entire existence of the universe.)

And this is the CONFIRMED insanity of the universe. There are nuttier theories out there, like the many-worlds interpretation of quantum probability. I reject it in favor of the copenhagen theory, but let me list both.

One form of confirmed insanity is superpositions, in which particles are in two conflicting states at the same time. Trying to measure this condition typically collapses it into one or the other. Superpositioning is what makes quantum computers so good at breaking cryptography -- They can collapse the superposition such that the correct key is produced, and the message quickly decrypted. However, the nature of this collapse is disputed.

Copenhagen theorists like myself state that the superposition collapses in an arbitrary fashion. That is, it is impossible to know which way it will go before the collapse. Once collapsed, the particle is in a consistent state.

Many worlds theorists, however, dislike this arbitrariness, and state that what actually happens in a collapse is that the universe is divided into two universes, one of which has the collapse go in one way, and the other of which the collapse goes into the other. It is impossible to know into which universe one will be sorted until it happens, but the split has occured so many times as to be practically infinite by now.

Supposedly we humans think using quantum effects too, so every time you've been offered a decision, you've also split the universe. You can surely see where the insanity of this is leading. There are universes in which you were never born, because your parents never got together. There are universes in which history unfolded in amazingly different ways, such as fascist victory during the second world war, or even the war replaced with a different one or averted altogether. There are universes in which the earth never formed. And there are universes that are exactly like this one, except this one chunk of uranium that has 1 x 10^21 radioactive atoms in this universe only has 2.7 x 10^19 in that one, because the radioactive decay actually did decay more times in that one. And likely by the time you've had the educational experience to read and understand this blog, you've had decisions that, in other universes, killed you off.

Yes, in other universes, you died. Maybe you forgot to look both ways before crossing the street and were run over by a car. Maybe you walked carelessly and fell to your death. Maybe your stove exploded when you tried to make breakfast.

If there are other universes, what separates us? Could other universes invade ours? Could we invade theirs? The whole thing must be too crazy to be true.



Cairnarvon said...

Many-worlds is interesting as a metaphor or a sci-fi plot device, but that's about it. It's too easily abused by laypersons.

By the way, you may want to look into something like Mimetex for posting formulae.
I have a Mimetex binary uploaded if you want to use mine rather than dick with installing your own, here.
Just write your TeX formula after it and use it as the src for an img tag, like so:
<img src="http://cairnarvon.rotahall.org/cgi-bin/mimetex.cgi?g=G*\frac{m_1*m_2}{r^2}" />

It's not the prettiest solution out there (the Mimetex page itself lists some prettier ones), but it's easy and convenient, and probably better than ASCII.

themadengineer said...

Thanks for that, it really cleaned up.

I'll work on my own TeTex installation next time I need to have a formula.

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