Wednesday, August 13, 2014

As Simple as Possible

"Make everything as simple as possible, but no simpler." -- Albert Einstein

I ran across this quote from a book I finished last week, which took me WAY too long to work through: The Fabric of the Cosmos: Space. Time. And the Texture of Reality by theoretical physicist Brian Greene. You may or may not have noticed that I updated my reading list along the side of the blog, and one of the books I'm currently reading is his earlier book The Elegant Universe, which is certainly the book that brought him his fame.

The book is really a build up to the most prominent "Theory of Everything" (ToE) called Superstring Theory (String Theory, for short). Of course, he spent some time talking about Classical Physics, and then the theories from the 20th century: Einstein's theories of relativity (Special and General), and Quantum Mechanics. Generally speaking (pun?), Special and General Relativity are theories about the macroscopic universe ... big things; things larger than the atomic and sub-atomic levels. Alternately, Quantum Mechanics has to do with the atomic and sub-atomic realms ... the world of the very small. These two theories are at odds with one another, and yet both are successful in their respective areas.

Since the mid-19th century, physicists have been able to demonstrate that many of the forces in the universe are actually different sides of the same coin. For example, Faraday demonstrated that electricity and magnetism were different expressions of the electro-magnetic force. Maxwell then took this brilliant idea and expressed them in mathematical formulas, which are among the most famous equations today and known as Maxwell's Equations.

Light, being an electro-magnetic wave moves at the speed of light, which is the speed limit of the universe. Einstein then posed the question: relative to what does light move at approximately 300,000 km/s? Here's what I mean ... let's suppose that a ship was moving at 1/2 of the speed of light and shone a bright flashlight pointing in front of it. Wouldn't the ship's speed add to the inherent speed of light? And therefore, wouldn't the speed of the light coming out from the ship be 1.5 light speed (also the speed capability of the Millenium Falcon)? Surprisingly, and very much at odds with our natural inclinations, Einstein determined that light will always travel at 300,000 km/s relative to everything ... even objects in motion. If we were to measure the speed of the light coming out from the spaceship, we would measure it at the speed of light, and no faster.

Kind of odd, isn't it? The first time I had this question put to me, I honestly thought the answer was going to be that light coming off of objects in motion would add the object's additional speed to the inherent speed of light. That's the beauty of Einstein's theories of relativity: they prove that light is constant for all perspectives and one's state of motion. If you were traveling at 99% of the speed of light and shone a light beam in front of you, you would measure it going at the constant speed of light.

One of the by-products of Einstein's theories is that there was a trade-off in saying that light's speed is constant for all perspectives and all states of relative motion, and what was given up was the idea of space and time as fixed constants. He argued that space and time could warp and bend depending on one's motion, or because of intense gravity. Furthermore, space and time were discovered to be intimately related and were given the name "Space-time" by Einstein. [As a quick side-note, you might be wondering about what space is. If you take all the matter out of space, is it really empty space? Einstein would say no, space is definitely a something. Space can bend, warp, twist, and it is also permeated by the Higgs Field (you might remember the discovery of the Higgs Boson in 2012), which is believed to give all matter its determined mass. Again, very counter-intuitive!]

Special and General Relativity have worked incredibly well for all things that we can see: things on Earth, in our solar system, and galaxies stemming to the edge of the visible universe. Where Einstein's theories break down is when we come down to the quantum (atomic) level. For the world of the tiny, Quantum Mechanics is the prevailing theory that is able to explain, with remarkable precision, predictions about the nature of fundamental particles. The troubling thing about Quantum Mechanics is that it is confusing. Though you might be able to easily grasp the basic concepts of Relativity, Quantum Mechanics are more challenging.

One of the most important aspects of Quantum Mechanics is the Heisenberg Uncertainty Principle, that basically states that we cannot know both a particle's position AND velocity. The more we know of one, the less we know of the other. Then there's the fact that all matter has particle and wave aspects to them. And of course, the lack of certainty wouldn't be complete without the recognition that we can't know the precise location of a particle until we observe it. It shouldn't come as a surprise that Quantum Mechanics is not about providing certainty. Rather, it seeks to provide probability. Oh yes ... there are some pretty complex formulas and theories to explain these things, such as Schrodinger's Probability Wave Function. One of the conclusions made by Quantum Mechanics is that a particle will function as a wave until we observe it, and then we can discover it's position, and in doing so will sacrifice information about it's velocity.

The big difference between the realm of particles with the macroscopic world in which we see, is that the quantum world behaves so differently. Theorists call this "Quantum Weirdness," which just brings a smile to my face. Confused? Not convinced? You are not alone. In fact, Richard Feynman, one of the most famous Quantum Physicists, made this famous statement: 
"If you think you understand quantum mechanics, you don't understand quantum mechanics." 
With regards to the concept of not knowing the location of a particle until you observe it, Einstein said this: 
"I like to think that the moon is there even if I am not looking at it."

Now onto the good stuff. Superstring Theory is an attempt to unify these two theories to explain all four of the forces in the universe, and objects of any size. This is an impressive goal, one that Einstein spent the last decades of his life pursuing, though he was completely unsuccessful. String Theory has made real progress and is the best contender to create a unified field theory, a so-called Theory of Everything. A ToE doesn't claim to explain literally everything about every field of science or study, but only to unify the known forces in the universe.

String Theory says that just as atoms are comprised of sub-atomic particles, there are even more fundamental elements that make up everything: strings. They theorize that what makes a string a sub-atomic particle is its vibration, just like a violin string can play different notes, so can the fundamental building blocks of matter. These strings also help explain another unique aspect of this theory: that there are 10 or 11 dimensions. Where are these extra dimensions? They are very very small, and seemingly invisible with today's instruments. Instead of the three spacial dimensions, and one time dimension, String Theory claims there are 6 or 7 additional spatial dimensions. Most importantly, String Theory removes the difficulties between Relativity and Quantum Physics.

A lot has yet to be proven. For instance, these alleged strings are significantly smaller than our instruments can measure, and perhaps will ever be able to measure. However, someday we might be able to indirectly prove the existence of strings, similar to how they've proven the existence of black holes. This would also help to explain these unseen spatial dimensions. In formulating a unified field theory, they hope to be able to more accurately explain what happens inside of a black hole, or what happened at the beginning of creation (obviously there are some areas I'd disagree on because of the truth of Christianity).

It is an exciting time for the field of science, because even if we aren't able to craft a workable unified field theory ... a Theory of Everything ... at least we can rule out some possibilities. My hope is that we are able to make major headway in conjuring up some workable theory, but either way, it's the journey that excites me and keeps me interested. If Superstring Theory proves to be correct, then it would demonstrate in another beautiful way in which the Lord of all Creation structured the entirety of His universe, using a symphony of strings, each vibrating at His command.

Thanks for reading,

No comments:

Post a Comment