I'm going to take a break from the mind-boggling and exciting paradoxes and explain what the universe is actually made of.
We've all heard about the molecule, and the atom, and the electrons, protons, and neutrons. Are those the building blocks of the universe? And what about these darned "photons"? Are they a brick also? Ever heard of a "graviton" or a "quark"? How do they all fit together?
Well, it all fits together seamlessly, like a cosmic orchestra. And here, you might see the slightest glimmer of the hottest thing in physics right now -- The String Theory.
What happens when you cut a block of salt in half? You get something a smaller block of salt. Cut that in half again...and it's an even smaller piece. You can do that again and again until you find a single molecule of salt...if you cut that down any more, it ceases to become salt. If you cut a molecule in half, you get two different atoms - Sodium and Chloride. Those nightmares from Chemistry coming back to you?
Pretty much, everything is made up of atoms. For quite a while, scientists thought that atoms were the smallest thing you could have. You can't cut an atom in half, because...well, there's nothing smaller to make it out of, the same way that you can't cut a pixel on your monitor in half.
But eventually, as scientists looked deeper, they found out that Atoms were made out of even smaller things put together. Basically, you have a bunch of electrons orbiting a dense nucleus, which is in turn made out of protons and neutrons.
Protons, Neutrons, and electrons. Are they the smallest building blocks of everything? Is everything in the world made out of a combination of them?
That was truth, until scientists found out that protons and neutrons were actually made up of brothers and sisters of the electrons - quarks (or, up quarks and down quarks). Electrons and the Two Quarks were now elementary particles. As of right now, science holds electrons and the two quarks to be a smallest, indivisible form of matter. The quarks are bigger than the electron, but basically they were like siblings in the cosmic family tree.
There you have it. The most common elementary particles are Electrons and Quarks. You could make pretty much anything in the world with them. Now let's run down the family -
Electron - Has an electrical charge of -1. Has a mass of 0.00054 u.
Up Quark - Has an electrical charge of +2/3. Has a mass of 0.0047 u.
Down Quark - Has an electrical charge of -1/3. Has a mass of 0.0074 u.
So...now that we have our puzzle pieces, let's construct an atom :)
Let's build an atom of Gold with our building blocks. We know that stable gold has 79 electrons, 79 protons, and 118 neutrons.
First, electrons -- there are 79 of them. Easy enough. But what about our 79 protons?
Scientists discovered that protons, with +1 charge, are made out of two up-quarks and one down-quark. And it makes sense, right? The electrical charge of two up-quarks (4/3) added to the negative charge of one down-quark (-1/3) comes out at 3/3, or an even 1. So we add 79 protons, each with two up-quarks and one down-quark.
So then what are neutrons, with 0 charge? They are simply one up-quark and two down-quarks. The charge of one up-quark (+2/3) added to the negative charge of two down-quarks (-2/3) adds up to 0. We add 118 neutrons, each with one up-quark and two down-quarks.
That's a brief exercise with adding up elementary particles.
Scientists have actually discovered a total of 12 elementary particles, arranged into three generations of four each. The generation we just discussed consists of the electron, the quarks, and a "neutrino", which isn't all that important.
If you have any questions, please ask them in the comments. I'd be happy to simplify or elaborate.
a quick summary - Most of the matter in the universe is made out of electrons and the two quarks. Protons are two up-quarks and one down-quark, and neutrons are one up-quark and two down-quarks.
I know this post seems like a boring chemistry lesson, I'm sorry...but I just wanted to get this established long before we go into the String Theory, which is where the real fun begins.
I'll be talking on the Force Carriers (protons, gravitons, etc.) later. They're a completely different breed.
Wednesday, November 01, 2006
The Stuff the World is Made Of
The Double Slit Experiment
Ah...the infamous Double Slit Experiment. For those of you who have heard of it before, it probably gave you a headache. For those of you who have no idea what it is, then prepare to be rocked.
There is no mathematical formula, no fancy theory that needs to be known to fully appreciate it. The experiment in itself is enough to be appreciated by someone who doesn't know a thing about quantum physics...or normal physics, for that matter.
At first glance, this is what you see. No mirrors, no magic -- tiny balls of matter acting more like waves in water, "sentient" electrons (although as we will see, that's a bunch of BS), and objects that are apparently two places at once.
In fact, it can be said that the easiest way to fully grasp what quantum physics truly is is to see this experiment. It's often one's first glimpse into the world of Quanta...and often not the last.
There's a famous video from the movie "What the Bleep do we Know?" that's been circulating the internet. If you watch it, I don't have to go through the process of explaining it. It actually does a pretty good job! I'd recommend anyone to watch it, even if they know nothing about quantum physics.
Anyway, this video can explain it better than I can ever do it without pictures. So until I get around to making pictures, please watch it before you continue.
What actually happens? Why does matter behave like a wave? That question deserves an entire post for itself.
Then video tries something that I think is completely absurd. It puts a little eyeball next to the slit and goes "Okay, which one does it go to? We'll watch with the eyeball." Then they fire another electron...and the result is no longer an interference pattern, but two bands, again.
Woah, did the electron know it was being watched, and decided to act like a particle instead of a wave?
While there are obvious psychedelic properties to that theory, it is unfortunately total sensationalism. The video is just hyping things up.
How do they actually observe the electron? Basically, they do the same thing that we do with our eyes. They bounce things (light light rays/photons) off of the electron and observe how the things bounce back. But Electrons are so small that shining light on it will affect its movement. That is, the strength of the light will actually push the electron, just like a wave of water pushes a bouy.
So the electron doesn't change by "just observing", as if by magic. The electron is changed by the way that we observe, as a side-effect.
This is the basicness of the Heisenberg Uncertainty Principle...which warrants a whole post of its own.
A quick summary - When you fire tiny bits of matter through two slits, it behaves like a wave instead of like matter. Why? It's complicated and I'll demonstrate it in simple terms later. So which slit does it actually go through? When they try to observe exactly which one, the electron appears to "decide to become matter again because it knows it is being watched". This isn't exactly true, but it sounds cool. Freaky. Sentient electrons, particles acting like waves...this isn't the last of the Double Slit experiment for this blog. This is just a basic overview.
Hm...well, this article isn't as great as some of my others. You probably have alot of questions about the video. Please leave them in the comments,a nd I'd be glad to answer. Or if you're just passing by, I'd love to see hear your opinions.
Elephant into a black hole
I guess there will be two kinds of posts in this blog - Paradoxes and Solutions. One type of post will show you two facts that are both true, yet state opposite things. The other will look at these paradox and provide apparent solutions.
To be honest, I like paradoxes more, because (ironically) they're alot easier to understand.
Here's a story that was posted recently on Digg - The elephant and the event horizon. Don't try to read the article unless you want your brain to explode or melt down. But there are some shiny pictures.
The idea here is simple - what happens when you throw an elephant into a black hole?
For one, you'll probably get a bunch of animal rights activist on your tail. And maybe some Thai warrior/protector will try to run after it to take it back. But aside from the social repercussions, what happens...physically?
I'm going to introduce a pair of characters that I'll be using a lot in this blog. One day, two friends named Steve and Anna got bored and decide to throw an elephant into a black hole. Anna will watch the elephant entering the black hole from a safe distance, and Steve the daredevil will ride the elephant into the black hole.
So what winds up happening? (Note - if at any time you get lost, just scroll down to the bolded "quick summary")
Anna watches as the black hole pulls the elephant towards it at super-fast speeds. But then something strange happens when the elephant reaches the Event Horizon (the point of no return) -- it vaporizes.
That's right...Steve and Mr. Elephant are just sailing through space when BAM, they get vaporized when they hit the event horizon. Anna detects some radiation coming out from the black hole, and thinks that the elephant smashed into a brick wall and shattered into pieces that is contained in the radiation.
That's all nice and well...but what about poor Steve? Can we travel with him during his last moments?
Steve, on the elephant, flies through space towards the black hole. Having heard about the vaporization thingy, he braces himself before he hits the event horizon. But when he finally hits it...nothing happens. Instead it's just business as usual. He and the elephant continue flying towards the black hole. Eventually the immense gravity shreds them, but overall, nothing happens at the event horizon.
Wait...what just happened?
Anna just saw the elephant get vaporized at the event horizon, its remains coming off as radiation.
Steve just went through the event horizon, and nothing special happened.
So where is the elephant, or its remains? Is it flying through space like normal, or is it no longer even tangible, existing as radiation?
From what we see, it must be at both places at once! Steve sees that it's normal, Anna sees that it's vaporized. And according to relativity, they're both right in thinking so. So the exact same elephant is in two places at once?
Wait...what if...going through the event horizon cloned the elephant? So it's not the same elephant...it's just two different elephants that have the same matter!
...but that can't be. Even the most basic laws (the first laws of thermodynamics, for example, which states that matter, energy, and information cannot be created or destroyed, only rearranged) forbid it. Quantum laws state that it isn't so, either.
So...there's the paradox, isn't it?
A quick summary - From someone looking on the outside, the elephant is vaporized when it hits the event horizon. From someone looking from the inside, the elephant goes through as normal. And science says they're both right.
What the heck is happening?
Don't try to make sense of it. Just take it all in, just as it is, piece by piece.
This, my friends, is what makes this stuff amazing, elegant, and beautiful.
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Please leave a comment if you have questions or something to say. This is mny first post, and I'd appreciate feedback :)
