Because my last two posts were quite lengthy, I’ve decided to limit myself to 1000 words on this one. Before I begin, I must credit the physicist Brian Greene for much of the insight and some of the examples I’m going to use. Without his book The Elegant Universe, I wouldn’t know where to begin in trying to explain string theory.
In short, string theory is the leading candidate for a theory of everything; a solution to the problem of trying to connect quantum mechanics to relativity. Because it has yet to be proven experimentally, many physicists have a hard time accepting it and think of it as nothing more than a mathematical contrivance. However, I must emphasize, it has also yet to be disproven; in fact many of the recent discoveries made in particle physics and cosmology were first predicted by string theory. Like quantum mechanics when it was first conceived, it has divided the physics community in two. Although the theory has enlightened us to some features of our universe and is arguably the most beautiful theory since Einstein’s general relativity, it still lacks definitive evidence for reasons that’ll be obvious later. But there is some hope on the horizon. After two years of upgrades, in the upcoming month, the LHC—the particle accelerator that discovered the Higgs Boson (the God Particle), will be starting up again to dive deeper into some of these enlightenments that string theory has given us and may further serve as evidence for it.
So now that you have a general overview, let’s get to the nitty gritty. According to the theory, our universe is made up of ten to eleven dimensions, however we only experience four of them. Think about the way in which you give someone your location. You tell them you’re on the corner of Main and Broadway on the second floor of such-and-such building. These coordinates represent the three spatial dimensions: left and right, forward and back and up and down that we’re familiar with. Of course you also give a time in which you’ll be at this three dimensional location and that is dimension number four.
Where are these other six to seven dimensions hiding then? They’re rolled up into tiny six dimensional shapes called Calabi-Yau shapes, named after the mathematicians who created them, that are woven into the fabric of the universe. You can sort of imagine them as knots that hold the threads of the universe together. The seventh possible dimension comes from an extension of string theory called M-theory, which basically adds another height dimension, but we can ignore that for now. These Calabi-Yau ‘knots’ are unfathomably small; as small as you can possibly get. This is why string theory has remained unproven, and consequently saves it from being disproven. With all the technology we currently possess, we just can’t probe down that far; down to something called the Planck length. To give you a reference point of the Planck length, imagine if an atom were the size of our entire universe, this length would be about as long as your average tree here on Earth.
Calabi-Yau shapes, or ‘knots’ that hold the fabric of the universe together.
The exact shape of these six dimensional knots is unknown, but it is important because it has a profound impact on our universe. At its core, string theory imagines everything in our universe as being made of the same material, microscopic strings of energy. And just the way air being funneled through a French horn has vibrational patterns that create various musical notes, strings that are funneled through these six dimensional knots have vibrational patterns that create various particle properties, such as mass, charge and something called spin. These properties dictate how a particle will influence our universe and how it will interact with other particles. Some particles become gravity, others become the forces that attract, glue and pull apart matter particles. This sets the stage for particles like quarks to coalesce into protons and neutrons, which interact with electrons to become atoms. Atoms interact with other atoms to become molecules and molecules interact with other molecules to become matter, until eventually you have this thing we call the universe. Amazing isn’t it? The reality we perceive could be nothing more than a grand symphony of vibrating strings.
Many string theorists have tried to pin down the exact Calabi-Yau shape that created our universe, but the mathematics seems to say it’s not possible; that there is an infinite amount of possibilities. This leads us down an existential rabbit hole of sorts and opens up possibilities that the human brain may never comprehend about reality. Multiverse theorists (the cosmology counterparts to string theorists) have proposed that because there is an infinite number of possible shapes that there is an infinite variety of universes that could all exist within one giant multidimensional form called the multiverse. This ties in with another component of the multiverse theory I’ve mention previously; that behind every black hole is another universe. Because the gravitational pull within a black hole is so great, it would cause these Calabi-Yau ‘knots’ to become detangled and reform into another shape. Changing this shape would change string energy vibrations, which would change particle properties and create an entirely new universe with a new set of laws for physics. Some may be sustainable—such as in the case of our universe—or unsustainable. Trying to guess the exact Calabi-Yau shape a black hole would form would kind of be like trying to calculate the innumerable factors that make up the unique shape of a single snowflake.
The multiverse theory along with M-theory also leads to the possibility that forces in other universes, or dimensions, may be stronger or weaker than within ours. For example gravity, the weakest of the four fundamental forces in our universe, may be sourced in a neighboring universe or dimension where it is stronger and we are just experiencing the residual effect of what bleeds through. Sort of like muffled music from a neighbor’s house party bleeding through the walls of your house. The importance of this possibility is gravity may be a communication link to other universes or dimensions—something that the movie Interstellar played off of.
Well I’ve gone over by 52 words now (sorry I tried my best!), so until next time, stay curious my friends.
My next blog topic was scheduled to be a crash course in String Theory as it seemed like a logical follow-up to a previous post, A Crash Course in Relativity and Quantum Mechanics. However as I was trying to put together this crash course on String Theory, I realized that while my previous post did an excellent job of explaining the basics of relativity, it was far too brief on the basics of quantum mechanics (so much so that you should just regard it as a crash course on relativity). It could also be that I’m just procrastinating in writing a blog post on String Theory because, as you can probably assume, it’s not exactly the simplest of tasks. So in the name of procrastination I’ve decided to write a comprehensive overview on something much easier (in comparison): quantum mechanics. I not only want to explain it, but to also tell the dramatic story behind its development and how it has not only revolutionized all of physics, but made the modern world possible. While you may think of quantum mechanics as an abstract concept unrelated to your life, without it there would be no computers, smartphones, or any of the modern electronic devices the world has become so dependent on today. Before we begin, unless you’re already familiar with the electromagnetic spectrum, I recommend reading my post, Why We Are Tone Deaf to the Music of Light before reading this. While it’s not necessary, if you begin to feel lost while reading, it will make this post much easier to swallow.
In 1900 the physicist Lord Kelvin (who is so famous there’s a unit of measurement for temperature named after him) stated, “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.” As history now tells he couldn’t have been any more wrong. But this sentiment was not one he shared alone; the physics community as a whole agreed. The incredible leaps we (the human race) made in science during the 19th century had us feeling pretty cocky in thinking we had Mother Nature pretty much figured out. There were a few little discrepancies, but they were sure to smooth out with just some ‘more precise measurement’. To paraphrase Richard Feynman (as I so often do), Mother Nature’s imagination is much greater than our own; she’s never going to let us relax.
The shortest summary I can give of quantum mechanics is that all matter exhibits properties of a particle and a wave on a subatomic scale. To find out how we came to such a silly conclusion, let’s begin with one of the above referenced discrepancies which was later called the ultraviolet catastrophe. The UV catastrophe is associated with something called black body radiation. A black body is an ‘ideal’ body that has a constant temperature, or is in what is called thermal equilibrium and radiates light according to that body’s temperature. An example of a body in thermal equilibrium would be a pot of cold water mixed into a pot of hot water and after some time it settles down into a pot with room temperature water. On the atomic level, the emission of electron energy is matched by the absorption of electron energy. The hot, high energy water molecules emit energy to cold ones making the hot ones cool down and the cold ones warm up. This happens until all the molecules reach a consistent temperature throughout the body. Another easily relatable example of a black body is us, as in humans. We and all other warm-blooded mammals radiate light in the infrared spectrum; which is why we glow when we are viewed through an infrared camera.
As you are aware, we cannot see the infrared light we emit with the naked eye because the frequency is too low for our eyes to detect. But what if we were to raise our body’s temperature to far higher than the 98.6 degrees F we’re familiar with? Won’t those emitted light waves eventually have a high enough frequency to become visible? The answer is yes, but unfortunately you’d kill yourself in the process. Let’s use a more sustainable example such as a kiln used for hardening clay pottery. If you were to peer through a small hole into the inside of the kiln, you’ll notice that when it’s not running it is completely black. Light waves are being emitted by the walls of the kiln but they are far too low in frequency for you to see them. As the kiln heats up you notice the walls are turning red. This is because they are now emitting light waves with a high enough frequency for your eyes to detect. As the temperature continues to rise the colors emitted move up the color spectrum as the light wave frequency continues to increase: red, orange, yellow, white (a combination of red, orange, yellow, green and blue produces white), blue and maybe some purple.
Now according to this logic of thinking, and classical physics of the time, if we were to continue to increase the temperature we should be able to push the emitted light from the visible spectrum into the ultraviolet spectrum and beyond. However this would also mean the total energy carried by the electromagnetic radiation inside the kiln would be infinite for any chosen temperature. So what happens in real life when you try to heat this hypothetical kiln to emit light waves beyond the visible spectrum? It stops emitting any light at all, visible or not.
The infinitely increasing dotted represents what the accepted classical theory of the time said should happen in regards to black body radiation. The solid line represents experimental results. Reference these graphed lines from right to left since I refered to light waves increasing in frequency not length.
This was our first glimpse into the strange order of the subatomic world. The person who was able to solve this problem was a physicist by the name of Max Planck who had to ‘tweak’ the rules of classical wave mechanics in order to explain the phenomenon. What he said, put simply, is that the atoms which make up the black body, or in our case the kiln, oscillate to absorb and emit energy. Think of the atoms as tiny springs that stretch and contract to absorb and emit energy. The more energy they absorb (stretch) the more energy they emit (contract). The reason no light is emitted at high energies is that these atoms (springs) have a limit to the energy they can absorb (stretch) and consequently emit. Once that limit is reached they can no longer absorb or emit energies of higher frequencies. However what this implied is that energy cannot be any arbitrary value, as a wave would suggest, when it is absorbed and emitted; it must be absorbed and emitted in distinct whole number values (or in Latin quanta) for each color. Why whole number values? Because each absorption and emission (stretch and contraction) by an atom can only be counted in whole number values. There could be no such thing as a half or a quarter of an emission. It would sort of be like asking to push someone on swing a half or a quarter of the way but no farther. Planck was fervent in stating though that energy only became ‘quantized’, or came in chunks, when it was being absorbed and emitted but still acted like a wave otherwise. The notion of energy as a wave was long established experimentally and was something no one would question—unless you’re Einstein as we’ll see later. How did Planck come to this conclusion? Through exhausting trial and error calculating, he found that when the number 6.63 ×10−34 (that’s point 33 zeros then 663) was multiplied against the frequency of the wave, it could determine the individual amounts of energy that were absorbed and emitted by the black body on each oscillation. When calculated this way, it matched the experimental results beautifully. Whether he truly believed that energy came in quantifiable chunks, even temporary ones, is left to question. He was quoted as stating his magical number (later to become Planck’s constant) was nothing more than a ‘mathematical trick’.
If you’re a little lost, that’s okay. The second discrepancy I’ll address will make sense of it all called the photoelectric effect. To summarize plainly, when light is casted upon many metals they emit electrons. The energy from the light is transferred to the electron until it becomes so energetic that it is ejected from the metal. At high rates, this is seen to the naked eye as sparks. According to the classical view of light as a wave, changing the amplitude (the brightness) should change the speed in which these electrons are ejected. Think of the light as a bat and the electron as a baseball on a tee. The harder you whack the metal with light the faster those electrons are going to speed away. However the experimental results done by Heinrich Hertz in 1887 showed nature didn’t actually work the way classical physics said it should.
At higher frequencies (higher temperatures) of light, electrons were emitted at the same speed from the metal no matter how bright or how dim the light was. This would be like whacking the baseball off the tee and seeing it fly away at the same speed whether you took a full swing or gently tapped it. However as the intensity (brightness) of the light increased, so did the amount of electrons ejected. On the other hand, at lower frequencies, regardless of how intense the light was, no electrons were ejected. This would be like taking a full swing and not even dislodging the baseball from the tee. While it was expected that lower frequency light waves should take longer to eject electrons because they carry less energy, to not eject any electrons at all regardless of the intensity seemed to laugh in the face of well-established and experimentally proven light wave mechanics. Think of it this way, if you were to have a vertical cylindrical tube with an opening at the top end and a water spigot at the bottom end then placed a ping pong ball inside (representative of an electron lodged in metal), no matter how quickly or slowing the tube filled with water (low or high frequency light waves), eventually the ball will come shooting out of the top—obviously with varying velocities according to how fast the tube was filled. If energy is a continuous wave, or stream, ejecting electrons with light should follow the same principles.
Finally in 1905 somebody, that somebody being Albert Einstein, was able to make sense of all this wackiness and consequently opened Pandora’s box on wackiness which would later be called quantum mechanics. In his ‘miracle year’ which included papers on special relativity and the size and proof of atoms (yes the existence of the atom was still debatable at the time), Einstein stated that quantization of light waves (dividing light into chunks) was not a mechanic of energy absorption and emission like Planck said in regards to black body radiation, but a characteristic of light, or energy, itself—and the photoelectric effect proved it! Einstein realized that Planck’s magical number (Planck’s constant) wasn’t just a ‘mathematical trick’ to solve the UV catastrophe, it in fact determined the energy capacity (the size) of these individual light quanta. It was for this he’d later earn his only Nobel Prize.
So how did Einstein conclude this? Well let’s imagine a ball in a ditch. This will represent our electron lodged in metal. We want to get this ball out of the ditch but the only way to do it is by throwing another ball at it. This other ball will represent a quantum of light (later known as a photon). In order to do this you must exert a certain amount of force (energy) to give the ball a high enough velocity to knock the ball in the ditch out. So you call upon your friend to help you who happens to be an MLB pitcher. He’ll represent our high frequency (high energy) light source. Let’s say he can ‘consistently’ throw the ball with 10 units of energy (the units are called electron volts calculated by Planck’s constant times the frequency) and it takes 2 units of this energy just to dislodge the ball from the pit. 2 represents something called the work function in physics. Since it takes 2 units of energy to dislodge the ball, when the ball comes flying out of the ditch it will do so with 8 units of energy (10 – 2 = 8). This energy is called kinetic energy. Now let’s imagine there is ten balls in the pit so we clone our friend ten times (anything is possible in thought experiments). This is representative of turning up the light’s intensity. No matter how many balls are ejected from the pit they all leave with 8 units of energy. This is how we get a result of seeing an electron fly away from the metal at the same speed whether we smacked it or gently tapped it with high frequency light. Seeing your dilemma, your sweet grandmother also wants to help you dislodge balls from this pit. She’ll represent our low frequency light source. Unfortunately she can only throw with a force of 2 units of energy and while she may get the balls to roll a little bit, there isn’t enough kinetic energy left to dislodge them from the pit, no matter how many times we clone her (2 – 2 = 0). This is how we get the result of smacking the metal with a full swing of low frequency light and not see any electrons become ejected.
At the time, Einstein was still nothing more than a struggling physicist working at a patent office and his paper on the photoelectric effect took a while to get traction. However in 1914 his solution was experimentally tested and it matched the results to a tee. Proof that light had properties of a particle was hard to swallow because it had been so definitively proven as a wave during the previous two hundred plus years or so (something we’ll discuss more in part two of this series). In fact many of the forefathers of quantum mechanics, including Einstein and Planck, would spend the rest of their careers trying to disprove what they started. Truthfully, compared to our perception of reality, quantum mechanics is outrageous, but it is an undeniable proven feature of our world. How we figured this out is something we’ll continue with in the next part of this series. Until then, stay curious my friends.
An obviously very doped-up me after my colonoscopy
By Bradley Stockwell
To spare you of the intimate details, I’ll just say recently I’ve had some ‘digestive issues’. Two weeks ago I had a colonoscopy to check out these issues. Although I realized the possibility that they may be caused by something serious such as cancer, when my doctor presented me with that reality, it dug in a lot more than I thought. Fortunately, it seems this world is stuck with me a little longer for all my biopsies came out okay. However during the five days in which I had to wait to hear these results, I couldn’t help but contemplate my own mortality and what death means to me as an atheist.
For lack of a better label, I am an atheist but I am not spiritual-less. I find a deep sense of sanctity and humility in the scientific observations of nature. To make clear, this post is not intended to degrade or disprove anyone’s religious faith. The world is richly diverse in beliefs, cultures and opinions and I think that’s a necessary and beautiful thing. What I do have a problem with is the contention surrounding the subject of faith and I in no part want to contribute to it. The reason I love physics so much is it seeks to find unity amongst division and I apply that same philosophy in all facets of my life. Simply, I’m presenting how I sleep at night without believing in a god(s) or an afterlife because it is an honest question I’m frequently asked.
The primary source of my peace of mind comes from the laws of thermodynamics which describes how energy behaves. The first law, the conservation of energy, states energy cannot be created nor destroyed. This law was exampled in a previous post, Flight of The Timeless Photon, on how the photon (aka energy) is transformed from hydrogen proton mass into the life-providing sunshine we all know. The energy we consume, and consequently life, is all sourced from the sun. And the sun’s energy is sourced from the matter within the universe and to find out where the universe’s energy is sourced, we would’ve had to been around during The Big Bang. However according to multiverse theorists, it’s a good chance that it may have come from the matter of a previous universe which was chopped up and scrambled by a black hole into energy. Regardless, the point I’m trying to make is energy is immortal. It is the driver of the circle of life not just here on Earth but in the entire universe. As special as you think you are, you are nothing more than a temporary capsule of mass for energy to inhabit. Death is nothing more than a dispersion of this energy and this is what I take consolation in. When I die, all the energy that was me, my personality—my soul, my body even, still remains in this world. I’m not gone; just less ordered. I am a part of what keeps the arrow of time moving forward as the universe naturally moves from a higher state of order towards a lower—the second law of thermodynamics.
The universe is very cyclical. Life and death are just different stopping points on a grand recycling process. Matter, like our bodies, is created and recycled and energy, like our souls, is immortal and transferred. If you’re familiar with Dharmic beliefs, this probably sounds familiar. It’s funny how the world’s oldest religion, Hinduism, seemed to grasp these concepts thousands of years before science did. While I’m not a practicing Hindu, nor do I plan to be, if forced to choose it would be the closest to my belief system due to the many correlations I find between it and science. One correlation I was most awestruck by was the concept of Brahman to the laws of thermodynamics (aka the laws of energy) mentioned above. According to belief, Brahman is the source of all things in the universe including reality and existence. Everything comes from Brahman and everything returns to Brahman. Brahman is uncreated, external, infinite and all-embracing. You could substitute the word energy for Brahman and get a simple understanding of the applications of the first and second laws of thermodynamics.
If you can’t fathom the thought of an afterlife as some form of your current self, I can understand that. Once again I’m not here to convince you differently, I’m just presenting my viewpoint. However in regards to the value of life, I do hope to convince you that there is no deeper appreciation than through the eyes of science. I only stress this to debunk the perpetuated myth that science somehow devalues the beauty of this world by picking it apart. Once again, the reason I love physics is it widens the perspective of my existence through unifying the universe’s many diverse creations and movements. It connects me to the infinitely larger cosmos above yet also to the infinitely smaller universes below. I have an atomic connection to the stars, a chemical connection to the earth, a biological connection to life and a genetic connection to my fellow humans. When you see the world on so many dimensions, I can personally attest that suddenly everything becomes very interesting. Even the things we don’t give much thought to, like sunshine, weather, the way in which water ripples, or why your friend’s beer overflows when you smack the top of it with yours, become regularly appreciated with a new sense of awe and curiosity. The world becomes much more absorbing than anything a smartphone or television can provide and you find yourself wanting to experience everything it can offer. There’s no greater feeling than the intercourse between knowledge and experience. This perspective is perfectly captured by one of my idols, the great physicist Richard Feynman.
“I have a friend who’s an artist and has sometimes taken a view which I don’t agree with very well. He’ll hold up a flower and say “look how beautiful it is,” and I’ll agree. Then he says “I as an artist can see how beautiful this is but you as a scientist take this all apart and it becomes a dull thing,” and I think that he’s kind of nutty. First of all, the beauty that he sees is available to other people and to me too, I believe. Although I may not be quite as refined aesthetically as he is … I can appreciate the beauty of a flower. At the same time, I see much more about the flower than he sees. I could imagine the cells in there, the complicated actions inside, which also have a beauty. I mean it’s not just beauty at this dimension, at one centimeter; there’s also beauty at smaller dimensions, the inner structure, also the processes. The fact that the colors in the flower evolved in order to attract insects to pollinate it is interesting; it means that insects can see the color. It adds a question: does this aesthetic sense also exist in the lower forms? Why is it aesthetic? All kinds of interesting questions which the science knowledge only adds to the excitement, the mystery and the awe of a flower. It only adds. I don’t understand how it subtracts.”
When I finally do say goodbye to this world, I hope my friends and family will realize this is not actually the case. Everything that was me is still very much a part of this world, just partaking in a different dimension of it. The energy contained within my body will go back into the earth so that it can provide new life to the flora and fauna which kept me alive as I dined on them throughout my own life. Every joule of energy that was me will be released back into this world to live life anew. And will the unique combination of matter the winds of energy deposited as Bradley Stockwell be forgotten? Well I hope I will have done something impactful enough to be remembered by history, but if not, I can always depend on my beloved light particle, the photon, to ensure my existence will mean something. Explained in detail in my previous post, A Crash Course in Relativity and Quantum Mechanics, according to relative velocity time dilation, the photon’s existence is timeless relative to ours because it moves at the speed of light. A funny thing happens to time at the speed of light—it ceases to exist, at least relative to our perception of time. That is of course until I interrupt this so-called photon’s path by absorbing it as heat and become that photon’s entire existence; forever altering the universe. And this is not the only way the photon will preserve my existence. I of course don’t absorb all the photons I come into contact with—some of them bounce off me and are collected in the photon detectors (aka the eyes) of my friends and family members. These photons then create electromagnetically charged webs of neurons, better known as memories. Well until next time, stay curious my friends!