Human beings have an unquenchable thirst for knowledge and an urgent drive for understanding. The further we go on our quest for absolute truth and the deeper we plunge into the heart of the ultimate reality, the more profound our questions become. Could there be something more to this world of ours than that which meets the eye? Is there some elaborate design behind the infinite galaxies, stars, and planets, or are we simply at the mercy of a chaotic and unordered universe? What is it that has given rise to the mysterious and unexplainable phenomenon that we have labeled the cosmos? Throughout history, we have attempted to answer these perplexing and ineluctable questions through myths, religion, or science. Apparent in many of these explanations is the idea of a unity, the “One”, or a single entity that comprises all of reality.
To some, it is God’s presence. To others it is the Tao or simply “that which is, and, in the case of modern physics, it is infinitesimally small strings, oscillating and vibrating, like the strings of a violin, that comprise the fabric of our universe and “rhythmically beat out the laws of the cosmos” (18). is a revolutionary way of explaining the complexity of the cosmos. It is the unified theory of physics that Einstein searched for but never found. It forces us to look at the world in which we live in a drastically different and beautiful way.
String theory states that all aspects of our universe consist of infinitesimally small, vibrating loops of energy (14). Like Pythagoras’ idea of the “music of the spheres”, these universal strings vibrate and oscillate, producing different notes in a cosmic symphony. Strings are the most basic constituents of matter, “atoms” in the true sense of the word. According to physicists, string theory may hold the key to understanding the inner workings of the universe. As Brian Greene states in his book The Elegant Universe: String theory has the potential to show that all of the wondrous happenings in the universe — from the frantic dance of subatomic quarks to the stately waltz of orbiting binary stars, from the primordial fireball of the big bang to the majestic swirl of heavenly galaxies — are reflections of one grand physical principle, one master equation (5). String theory is the first theory able to combine the undeniable, yet conflicting truths of Einstein’s general theory of relativity and the newly emerging field of quantum mechanics.
String theory has become the Holy Grail of physics. In it lies the possibility to finally unify all aspects of the universe as we know it and bring us to the end of our journey in the quest for the “theory of everything” (16). The ancient Greeks made an amazingly insightful and accurate assumption that all matter is comprised of diminutive and “uncut table” particles they called atoms (7). 2, 000 years later, scientists have found that all matter is, in fact, comprised of basic elements, like oxygen and carbon, but they soon found out that even they were not the most basic constituents of matter (7). By the early 1930 s, various scientists had discovered that “atoms consist of a nucleus that consists of protons and neutrons and is surrounded by a swarm of orbiting electrons” (7). Then, in 1968, even smaller components of protons and neutrons were found, the up-quark and down-quark (7).
Since then, scientists have continued to slam bits of matter together, discovering new fundamental particles ranging in size from the smallest, ghostly neutrino that weighs less than 10^-8 (in multiples of the proton mass) to the largest top quark (8). Each of these particles also has an antiparticle partner (8). All matter encountered to date is comprised of a combination of these basic particles. Scientists have also discovered particles that account for the four fundamental forces that act upon matter (10).
The most familiar force to humans is gravity. The smallest constituent of this force is the graviton which has a mass of 0 (11). The next familiar of the four, the electromagnetic force, is carried out by the photon (11). This is the driving force behind lights, computers, televisions, and lightening (10). The strong force, responsible for keeping quarks glued together inside protons and neutrons and keeping protons and neutrons packed together in atomic nuclei, is exerted by the gluon which has a mass of 0 (11). The weak force and its particle the weak gauge boson is the force that is responsible for the radioactive decay of substances such as uranium and cobalt (11).
Unlike the other forces, the weak gauge boson has a mass of either 86 or 97 (11). While scientists have been able to carefully measure the properties of these basic constituents of matter, the numerical input is completely arbitrary. There is no explanation for why the particles have the properties they do (12). String theory claims it has the answer that will finally explain the seemingly random properties of the elementary particles.
String theory has come a long way on a long and tumultuous path to recognition in the scientific community. It began in 1968 when theoretical physicist Gabriele Venezia no came upon a striking revelation while trying to understand the nuclear strong force (136). He found that a 200-year-old formula created by Swiss mathematician Leonhard Euler (the Euler beta function) perfectly matched modern data on the strong force, but no one could understand why it worked (137). This changed when Yo chiro N ambu, Holger Nielsen, and Leonard Suss kind unveiled the physics beneath Euler’s strictly theoretical formula two years later (137). By representing nuclear forces as vibrating, one-dimensional strings, these physicists showed how Euler’s function accurately described those forces (137). The scientific community slowly lost interest in string theory when its description of the strong force made predictions that directly contradicted experimental findings (137).
At the same time, the point-particle quantum theory of chromo dynamics exhibited overwhelming success in describing the strong force, and so the standard model remained un threatened (137). Then, in 1974, John Schwarz and Joel Scherk studied the messenger-like patterns of string vibration and found that their properties exactly matched those of the gravitational force’s hypothetical messenger particle (138). Schwarz and Scherk argued that string theory had failed to catch on because physicists had underestimated its scope (138). Still, their work was ignored by the physics community because the conflicts between quantum mechanics and string theory remained unresolved (138). 1984 was a turning point for string theory. John Schwarz and Michael Green declared that string theory was not a strong force theory, but rather a quantum theory that also included gravity and was able to encompass all of the four forces and all of matter (138).
Schwarz’s and Green’s reinterpretation marked the first-ever quantum mechanical theory of the gravitational force (139). Research showed that string theory offered “a far fuller and more satisfying explanation than is found in the standard model” (139). The “first super string revolution” had begun. Still, physicists struggled while trying to determine the equations needed to prove string theory. This problem hindered further advancements, and many physicists gave up once again. The problem with string theory was that the equations themselves were so difficult that physicists could only deduce approximations of both the equations and their sol unions.
Then, in a groundbreaking lecture delivered in 1995, Edward Witten announced a plan for taking the next step. The “second super string revolution” began, and a light at the end of the tunnel had finally become visible. The basic premise of string theory is that if we could examine each elementary particle in the cosmos with a precision beyond our present technological capacity, we would find that each particle consists at its core of an infinitesimally small filament of vibrating energy called a string (14). Strings are the quantum equivalent of wave phenomena.
Each string can support a specific resonant pattern (143). Much like different vibrations of a violin string give rise to different musical notes, the resonant pattern of a fundamental string determines the mass and force charges of the various elementary particles (143). According to special relativity, the mass and energy of a particle are reciprocally related (145). Therefore, the energy exerted by the vibrating string determines the mass of the elementary particle, so higher energy resonant pattern (one with a greater amplitude and shorter wavelength) will result in an elementary particle with a greater mass (144, 145).
Strings are thought to be under contractive pressure, resulting in extreme tension of 10^39 tons, termed the Planck tension (148). The huge string tension causes the loops to contract to the Planck size, 10^-33 cm. As we know, the more tension a string has, the harder it is to pluck it (148). Therefore scientists understand that most strings must exert a huge amount of energy, known as the Planck energy. Greene states, ‘If we translate the Planck energy into a mass using Einstein’s famous conversion formula (E = mc^2), it corresponds to masses that are on the order of ten billion billion (10^19) times that of a proton, about the size of a grain of dust (149). This is known as the Planck mass.
If the natural energy of a string, results in such large particles, how, then, can strings be responsible for the tinier particles such as neutrinos? The answer is quantum jitter. Strings can become ‘out of sync h with themselves’, creating quantum vibrations that cancels its own energy and resulting in particles with smaller mass. Greene says, ‘In effect, through the weirdness of quantum mechanics, the energy associated with the quantum jitters of a string is negative, and this reduces the overall energy content of a vibrating string by an amount that is roughly equal to Planck energy’ (150). In order to have String Theory’s mathematics work, string theorists have gone back to some theories of Einstein’s time that, on the Planck scale, reveal several more dimensions of space. In research done prior to 1995, scientists have discovered 6 more spatial dimensions.
Then, in Witten’s famous speech in 1995, one more dimension was added, coming to a grand total of 11 spatial dimensions. What do these extra dimensions look like? Through mathematical formulas, Phillip Candelas, Gary Horowitz, Andrew Strom inger, and Edward Witten have discovered a class of six-dimensional geometrical shapes known as Chalabi-Yau spaces (207). These curled up balls of extra dimensions are so tiny that we are not aware of them, even though we are constantly moving through them. ‘As a string moves about, oscillating as it travels, the geometrical form of the extra dimensions plays a critical role in determining resonant patterns of vibration’ (206). These extra dimensions, while nearly impossible to imagine, are essential to an understanding of string theory. With the addition of an eleventh dimension, the five (and possibly six) isolated string theories are beautifully united in an even grander coalescence called M-theory (287).
Along with the vibrating strings of string theory, M-theory has discovered a space-time structure called a P-brave that can have any number of dimensions. Also, scientists suggest a prehistory to the universe, before time zero, in which instead of being tightly compacted into a ‘tiny spatial speck’, the universe was ‘cold and essentially infinite in spatial extent’ (362). Then, an instability kicked in, forcing every point in the universe to rush rapidly away from one another. This rushing caused space to curve, resulting in a dramatic increase in temperature. Somewhere within this vast expanse, a millimeter-sized three-dimensional region emerged, the foundation of the big-bang theory. But in a world where time rules our lives, can we really understand a moment before time and space even existed? Greene says, “Even our language is too coarse to handle these ideas, for, in fact, there is even no notion of before.
In a sense, it’s as if individual strings are “shards” of space and time, and only when they appropriately undergo sympathetic vibrations do the conventional notions of space and time emerge” (378). On top of that, recent research suggests the universe with its laws of physics that we understand may be just a blade of grass in an immense cosmic field known as the multiverse. While years of research have produced promising results, it is impossible to say if we have finally discovered the ultimate theory, or if there are even smaller microcosms of life. A central organizing principle is still missing. It may be years before scientists can fully comprehend the complexities of M-theory. But even if M-theory is proven, will an abstract series of mathematical formulas and theoretical dimensions finally give human beings meaning and the true understanding they strive for? The inherent problem with the approach of science in understanding something as complex as the origin and inner workings of the universe is that it fails to reconcile the fact that, as human beings, we are working within the constraints of the human mind and trying to understand something that is beyond human beings all together.
True understanding may very well be impeded by our existence as human beings. Then again, science has told us that we only use a very small percentage of our brains. The ability to understand may lie untapped in a realm of mind we have never before experienced. Perhaps, just as the universe evolves, the human mind will evolve and one day all will become clear to us. Or maybe not. It is possible that we were never meant to understand.
Perhaps our purpose here is to continue looking. No matter what we find, we will constantly strive for more. If we are finally able to create a technology to observe strings, we will then look to see if there is anything more basic than a string, and on and on until we must finally accept the fact that we will never discover the truth. To call string theory/M-theory the unified theory of everything is an overstatement. While it will have accomplished much in explaining the complexities of the physical workings of our universe, our search for complete understanding is never ending.
While we labor over our unanswered questions, we often forget to stop and look around at the truth and beauty right in front of our eyes. Einstein once said, ‘To know that what is impenetrable to us really exists, manifesting itself as the highest wisdom and the most radiant beauty which our dull faculties can comprehend only in the most primitive form-this knowledge, this feeling is at the center of true religiousness.’ Perhaps our journey is not meant to end in an ultimate, all encompassing, scientific theory full of mathematical formulas explaining every last thing in the universe, but in awe and reverence at all that is.