Recently I have been focusing a lot on science: studying quantum physics and astronomy has helped this summer be a tad bit more enjoyable. I have realized many physical truths about the world of which, not to my surprise, others are not aware. Because of this, I would like to take the time to inform you of these (exciting) things. I also want to seize this opportunity to test my scientific writing skills. I'm not saying I'm the tits at scientific writing, and I certainly do not talk this way with my friends, but if I were to write a scientific text or narrate an after-school special with Bill Nye, this is the way it would be handled. As well, you may have already noticed, my writing could not cut it in an advanced English class. (Haunting memories of my honors English class are returning...)
Scientific writing in my mind includes objective explanations of ideas with the occasional opinionated attack on an opposing viewpoint. It also includes analogies...a lot of analogies. These are necessary, Brooke can attest to this, in order for the equations to relate to the physical world we live in. Sometimes scientific writing can be pervaded by personal anecdotes but these I will try to avoid. Keep in mind all words are my own. (I haven't copied and pasted or quoted Dr. Hawking, etc.)
Now, on to the "lesson",
I have recently finished a book on string theory. This is the focus of my post. Now, one cannot simply jump into string theory and start being overwhelmed by its abundance of big words and confusing concepts without first understanding some widely-known fundamental ideas. No, before I allow you the joy of scratching your head and chucking your computer at the wall, we will cover the basics.
These ideas start with quantum theory. Once again, I'm afraid, we must start somewhere even more fundamental: the atomic world. We all know (at least I hope we all know) that matter is comprised of subatomic particles interacting to form atoms. These atoms are the building blocks of matter and they themselves are composed of protons, neutrons, and electrons. This is indeed fundamental and perhaps even elementary, but it is important idea to understand. Even my mum has no idea what the hell a proton is. Anyone who finds a parallel with my mother on this needs to find a dictionary post-haste.
You may think that an analysis of the world stops here. Well, shame on you then. If you delve further within the proton, you will find even smaller particles. I do not know what to call these other than sub-subatomic particles. Subbed sub...supersub....more sub than the other ones? Anyway, these particles are called quarks. There are top quarks and bottom quarks, up quarks and down quarks, blah, blah. Already you may be saying to yourself "gee, I didn't know that" or "haha...quark..." But there are other particles still. There are particles that are massless and independent of the atom. They are photons and gravitons. (Gluons also exist but as of writing this, I have no clue what the hell they are).
A photon is a particle of light. "But Ash, I thought light was a wave!!" ...Shut up, just keep reading. These particles travel at the speed of light from a point source. They are the reasons we see things. Photons can be reflected or absorbed by certain substances. For example, your bathroom mirror will reflect most photons while the wall next to it will absorb more photons. The reason you can see the screen right now is because the photons bouncing off and, more importantly, being emitted from your computer screen are reaching your eyes. This is the reason you see yourself in the mirror: the photons bouncing off your body reach the mirror and are reflected back to your eyes. Pretty nifty way to think about your morning routine, eh?
Gravitons are a bit trickier. We don't actually know if they exist. "WTF Ash!"...Again, just read. Gravitons are associated with, you guessed it, gravity. To conserve digital ink and to spare myself the trouble of an arduous explanation, I will simply say gravitons are to gravity as photons are to light. That is, the reason that we feel the effects of gravity is due to the emission of these particles and the way you perceive them. Gravitons may or may not exist. They are considered theoretical particles. The reason we include them in our analysis is because they are accounted for in the math. Yes, the math. If you aren't good at math, then there is even more reason to just play along. If gravitons do exist, they act much like photons do in the sense that they are both waves and particles at the same time. "I said that and you told me to shut up!"...Will you please stop interrupting? Your perfectly reasonable confusion is unsettling.
Both gravitons and photons are what are called massless particles. They have no mass. You could have 10^16 (one trillion trillion) photons and gravitons in a box and the box would be just as heavy as it was when it was empty. Pretty interesting to say the least.
What do photons and gravitons have to do with protons, neutrons, and electrons? Nothing really, except electrons and photons interact very often. Some of you may have heard of the photoelectric effect. This is when photons bounce off metals and cause the metal to emit electrons, yada, yada. On the other hand, electrons constantly emit photons. One may be lead to believe that if you could view an atom, its electron cloud would glow. I have no frickin' idea.
We can move on. I will briefly explain some quantum mechanics. Quantum physics is basically the study of the very tiny. "Atoms are tiny!"...Indeed they are, but quantum theories tend to focus more on individual particles, namely electrons. Now we all know (again, I hope this is so) that depending on the temperature of an object, it can exist as a solid, liquid, or a gas. At high temperatures, atoms, (or if we are speaking quantum mechanics, particles) move faster than at lower temperatures. If you freeze water, you get ice. This is because the particles in the water have slowed down and do not have the energy to spread out. They are almost stuck in place. The word 'almost' is key here and in quantum theory.
There is something called the uncertainty principle. The vaguest explanation I can give you is that you can never accurately locate an electron around the nucleus of an atom. When you focus on the tiny scale of the quantum world, things are no longer located at exact points in space. They are only 'most likely' to be there. Simply because an electron can be in a certain spot, it is. If you want a more in depth overview of this, I am sure a Google search box is 'most likely' to be near the top of your screen. Of course, I could be wrong. (Haha...?)
Even at 0 Kelvin (-273 degrees Celsius) particles are still moving, following this uncertainty principle. You can never ever make them stop altogether. This is because particles always experience quantum fluctuations, or vibrations if you prefer. These vibrations are due to their rest mass or rest energy. (E=mc^2) I will not dive any deeper into quantum physics, but this rough explanation will help out when we talk about string theory.
Just what is string theory? I bet this question has been swimming around in your head for quite some time...No? Whatever. Basically the premise of string theory is that beyond the atoms, beyond the subatomic protons and their respective quarks, beyond the photons and gravitons and gluons, there exist even smaller building blocks: strings.
When I first heard this idea I thought, 'Strings? Like the frayed ends of a rug?' Well actually a guitar string is more analogous to the ones in string theory. This is because strings under go the fore-mentioned quantum vibrations. The different ways a string can vibrate are called vibrational modes. The different modes produce different frequencies and these frequencies in turn develop into either a quark, an electron, a neutron, a photon, or any type of particle. Think of a guitar. When you strum a certain string on the guitar, you produce a note at its respective frequency. Strum a different string and a completely new note can be heard. You can easily relate this to string theory: depending on which frequency you vibrate at, a certain particle, or note, will be produced.
"How can I visualize a string theory string?" These strings can be infinitely long. (I believe these could be the infamous cosmic strings..Do not quote me). Or they can simply be points. (D-0 branes). The cool thing about strings is they can stretch in as few as two dimensions or as many as 11 dimensions. In reality, a string can have zero width and be quite long, such as a line drawn on a piece of paper. Or, in the case of 11 dimensions, a string can be...um...very...hmm......yes.
If you use string theory as an umbrella term, you will have to accept the fact that most of the claims require 26 dimensions all together. This seems false at first glance, what with our typical experience of four dimensions altogether: three of space and one of time. Again, its all in the math. Perhaps there are multiple dimensions of time as there are of space. It's really anyone's guess...not yours, though.
"Surely these strings aren't connected to the head of a guitar." Well don't assume that isn't true just yet. Strings can actually be connected to objects called branes. (Short for membrane). These branes can be point particles or they can be geometric shapes such as rectangles or even cubes. Branes are basically strings with multiple dimensions of length and they can curve around circular dimensions of space-time, distorting their observable structure. (Assuming one could actually observe such a thing). There is actually a theory that states that our entire universe exists on the surface of a 'brane world'. (This theory would be disproved with the discovery of the graviton).
Branes are interesting in that they exert gravitational force. Intriguingly, they also have a repulsion toward one another. (As if they have a like charge). Normally, one brane would exert a gravitatonal force on a similar brane, bringing the branes closer together, and a repulsive force, moving them apart. These two effects surprisingly cancel each other out, preventing the branes from moving with respect to one another. However, consider if you took a D-0 brane, a brane that is as small as a point with no length in either direction, and put it close to a stack of D-0 branes on top of one another. Here is a crude picture to illustrate:
1)
. ______
. ______
. ______ .
. ______D-0
. ______
stack
of D-0
2)
.__ movement
.__<--
.__ .
.__
.__
The stack's increased gravity actually prevails over the repulsive forces of the branes, rendering the single D-0 brane unable to escape the stack's gravitational pull. This tiny event is characteristic of an astronomical event we can observe in the real world: a black hole devouring objects in space. In fact, in this scenario the stack of branes is said to create a black hole horizon. (Something from which you cannot escape its gravitational pull).
I myself find this very obscure and difficult to wrap my head around. I think at this point, if you are even the slightest bit intrigued, then congratulations!
I understand questions must still be lingering, as I have not really described how string theory relates or interacts with the physical world we observe from day to day. The fact is, this description is still a work in progress. We still do not know how viable string theory really is and we still have yet to produce a 'theory of everything' to describe our universe. Whether string theory holds that title or not will become clearer in the years to come. Perhaps I can even facilitate that process, who knows?...not you.
All I wanted was to provide an appetizer to the all-you-can-eat buffet that is string theory. I feel I have achieved that much.
If you have any questions, talk to my agent. (Google). Or just comment on this post with any questions, you can bet I will muster up an answer.
