Written by Vishrut Kinikar
“God does not play dice with the universe” remarked Albert Einstein when quantum mechanics ushered a probabilistic view of the cosmos into the world of physics. However, through repeated experimentation, the validity of quantum mechanics has been upheld for surprisingly longer than most people expected.
Since antiquity, the world has been viewed as having been composed by fixed properties which do not fluctuate. The theory of Newton predicted the properties of massive objects with no element of uncertainty in their mathematical formulation. Einstein’s theory of relativity, although it did away with Newtonian concepts such as absolute space and absolute time, never introduced any sort of randomness or chance into its mathematics. The theory of relativity is what is known as a classical theory, where every event has a fixed location in space and a fixed point in time. The theory of special relativity predicted with great success, the speed of light in a vacuum, the ways in which speed affects mass, and the equivalence of mass and energy. The physical principle behind relativity is the equivalence principle, which states that acceleration in one frame is equal to gravitation in another frame. The general theory of relativity incorporated gravity into the picture by describing gravity as the curvature of space-time caused by the distribution of mass-energy. These theories again do not introduce any chance or randomness into its view of the cosmos. However, to the dismay of numerous classical physicists, the quantum revolution began in the 1920s when mechanics was reformulated into quantum mechanics by Erwin Schrödinger, Paul Dirac, Werner Heisenberg, and Niels Bohr. While relativity described the universe on the largest scales, quantum mechanics described the universe on the most minute scales, that of point-particles. One of the observations that paved the way for quantum mechanics to take shape was the uncertainty principle. As suggested by its name, the principle overthrew the long-held notion that every event had properties which could be measured with certainty. The uncertainty principle held that the position and velocity of a particle could never be predicted accurately. The position of a particle cannot be measured properly due to the fact that there is no wavelength of light as small as a point-particle. However, the more accurately we try to measure the position of a particle, the less accurately we can measure its velocity, and vice versa. This discovery by Werner Heisenberg challenged the classical viewpoint that every event had measurable characteristics. The next shock wave came with the wave-particle duality, demonstrated by the double-slit experiment.
Observation Changes Reality
The double slit experiment, even after numerous replicated trials, never failed to show that observation changes reality. In addition to this groundbreaking (and strange) realization, the double-slit experiment settled the debate around whether light is a particle or wave. In this experiment, a beam of electrons were propelled through a surface which has two slits, and the beam gave rise to patterns of light. However, the pattern of light exhibited wave-like properties. This result shook the ground beneath physicists. How could an electron, a particle, exhibit wave-like patterns of light? It is simply impossible as per the laws of classical physics. The only way it was possible for an electron to give rise to such patterns was if it traveled through both slits at the same time. An electron can never pass through two slits at the same time, the distance between which is millions of times greater than the electron itself. Only a wave could pass through both slits at the same time. The electron, however, displayed another result. It would also give rise to patterns characteristic of particles. During some trials, the electron gave rise a particle-like pattern but during others, it would give rise to wave-like patterns. How could light display both particle-like properties and wave-like properties? The only way for this result is possible is if light is both a particle and a wave at the same time. This result was further extended to all matter. Every particle was simultaneously a wave and every wave was simultaneously a particle. To add to this bizarre realization, the observer effect was theorized following this experiment. The observer effect, in the simplest words, means that observation can change reality. An observer can change reality by simply observing. In the experiment, both particle-like and wave-like properties were exhibited, but the particle-like pattern was only found when there was an observer overlooking the experiment and the wave-like pattern was only found when there was no observer overlooking the experiment. This meant that the electron would only collapse into a particle when observed. This may all seem like magic and sorcery, but in reality, it is due to the wave being a wave of probability. The wave represented the probability of the electron being in various different states at the same time, but when observed, the wave of probability collapsed into the most likely state. This meant that prior to being observed, the electron existed in various states and locations at the same time, each with a certain probability. However, after observation, it assumed one state. Imagine watching TV; while watching it, the TV is in one state and one location (on the wall) but when you look away, the TV ceases to exist. It simply becomes a wave of probability, with certain probabilities. One probability may be that it exists on the moon, another probability is that it exists on the floor. There are many such probabilities, but the highest probability is that of the TV being on the wall. When you finally turn to look at the TV once more, the TV assumes this most probable state and returns to existence on the wall. In simpler words, an object doesn’t exist when we don’t look at it. This can be illustrated more clearly with the Schrödinger’s cat thought experiment. Erwin Schrödinger visualized a cat being placed in a box with a flask of poison, a Geiger counter, and some radioactive material. Once the Geiger counter detects radioactivity, it will shatter the flask, releasing poison towards the cat. When the box is opened after this event, the cat will be either dead or alive due to the observer collapsing the state of the cat into either dead or alive. However, prior to the observer opening the box to look at the cat, the cat exists in a superposition of numerous states described by a wave function. The wave function includes probabilities of both dead and alive, meaning the before the box is opened, the cat exists in a nether state in which it is both dead and alive. This proposition that matter exists in a superposition of states prior to observation is known as the Copenhagen interpretation of quantum mechanics. This groundbreaking and bizarre idea led to many physicists accepting that reality has no independent existence without anyone to observe it. However, many other physicists refused to accept this idea. Albert Einstein rebuked “Does the moon exist simply because a mouse looked at it?”. The answer to this question, as per the Copenhagen interpretation is a firm “yes”.
However, a major flaw in the Copenhagen interpretation is that it has no answer to the question of how the universe exists. An object has to be observed in order to exist, meaning that the universe has to have some conscious entity observing it at this moment. But who is this conscious identity? Due to this flaw, many physicists reject the Copenhagen interpretation, however there are many that do accept it. One of the most prominent proponents of this interpretation was Eugene Wigner, a Hungarian-American physicist. Wigner used the Copenhagen interpretation to corroborate his belief that an all-pervasive consciousness, or God, was observing the universe. Wigner argued that God must be observing the universe for it to exist. Wigner was drawn to the Vedanta philosophy of Hinduism, which believes that God is a supreme consciousness which is all-permeating and omnipresent, from which he formed his idea about the Copenhagen interpretation. In fact, the entire premise of quantum mechanics originated from Indian philosophical concepts. The pioneers of quantum mechanics such as Erwin Schrödinger, Niels Bohr, and Werner Heisenberg oft-cited the Vedas and other Indian scriptures as their source of inspiration for their scientific ideas.
Niels Bohr was known to have said “I go to the Upanishads to ask questions”.
Werner Heisenberg said “After the conversations about Indian philosophy, some of the ideas of quantum physics that seemed so crazy suddenly made much more sense.”
Heisenberg went even further to say “Quantum theory will not look ridiculous to people who have read Vedanta.”
Such was Heisenberg’s fascination with Indian philosophy that he himself traveled to India to discuss his ideas with Shri Rabindranath Tagore, who he thought could clarify his doubts regarding science with his knowledge of philosophy.
Given this parallelism between Vedanta and quantum mechanics, the Copenhagen interpretation that observation changes reality originally took root in Vedantic philosophy. The concept of Vedanta from which the Copenhagen interpretation arose was that of Drishti-Srishti Vaad. This concept asserts that srishti (creation) arises from drishti (vision or observation). Drishti-Srishti Vaad also describes George Sudarshan’s research.
George Sudarshan was an Indian physicist widely known for his theorization of the tachyon, a theoretical particle which travels faster than light. He also performed groundbreaking research in the Copenhagen interpretation. Sudarshan was born in a Christian family in Kerala but later became a Hindu after being inspired by Vedic philosophy. Sudarshan, in his research, found new properties of the principle that observation alters reality. He claimed that observation doesn’t just collapse the wave function of an object like the Copenhagen interpretation holds, but is also capable of changing the probabilities in a wave function so that another state becomes more probable. This means that by observing an object in certain ways, the probabilities in its wave function can change accordingly. Meaning that simply by observing an object, it is possible to transform it into something completely different. Drishti-Srishti Vaad predicted these properties thousands of years before. The concept of Drishti-Srishti Vaad holds that Brahman, the supreme consciousness, used observation to transform Prakriti (the fundamental matter of the cosmos) into objects with well-defined properties such as the planets and galaxies. Brahman did this simply with observation. By Drishti (observation), Brahman was able to give rise to Srishti (creation). There exist numerous other parallels between quantum mechanics and Vedic philosophy.
The Four Fundamental Forces and Quanta
The universe is composed of four fundamental forces. It is these four forces of which physicists seek a unification. The only way to unify these four fundamental forces is through the unification of gravity and quantum theory, which will be discussed in later articles. These four forces are gravity, the electromagnetic force, the strong nuclear force, and weak nuclear force. These forces are composed of point-particles called quanta. Quanta is simply the plural for quantum which is the smallest and indivisible part of any entity. Gravity is described as a curvature space-time due to the distribution of matter-energy. However, in quantum mechanics, gravity is described as a point-particle known as a graviton. The electromagnetic force is described a particle called a photon, the strong nuclear force is described by a particle called a gluon, and the weak nuclear force is described by three particles called W and Z bosons. There are two W bosons (W+ and W– bosons) and one Z boson (Z0 boson). All of these particles have what is known as an integer spin. A spin is a measure of the angular momentum of a particle. Spin can be conceived of in simple terms as the amount of times needed to rotate a particle for it to look the same. For example, if a tennis ball is rotated 360 degrees, it will look the same as before. However, if we have an arrow-shaped object, then the object will look the same if turned only 180 degrees. Every single particle which carries force has an integer spin. Integer spin means that the particle needs to be rotated a full revolution or half-revolution in order to look the same. A tennis ball can be thought of as having an integer spin of 1 because it has to be rotated a full revolution (360 degrees) in order to look the same. Similarly, an arrow-shaped object can be thought of as having an integer spin of 2 because it has to be rotated a half-revolution (180 degree) to look the same. Photons, W and Z bosons, and gluons have spin 1 while a graviton has spin 2. Force carrying particles or integer spin particles are what are known as bosons. Bosons are named after the Indian physicist Satyendra Nath Bose, who along with Einstein developed the statistics of these particles. Matter particles have what is called half-integer spin or 1/2 spin. All matter is made up of these half-integer spin particles. Having a 1/2 spin means that the given particle has to be rotated two full revolutions to look the same. Although this may seem strange, it is a property consistent with the laws of particle physics. Half-integer spin particles are what are known as fermions (named after the Italian physicist Enrico Fermi).
Antimatter is an interesting phenomenon which arises due to its properties on the quantum level. Antimatter, as its name suggests, is the opposite of matter. Antimatter is composed of anti-particles. The anti-particle of a given particle has an opposite charge. When a particle and anti-particle meet, they will annihilate in a great burst of energy. The anti-particle of an electron (which is also a quantum) is known as an anti-electron or a positron. A positron has a positive charge and will annihilate if it comes into contact with an electron. In fact, many particles are their own anti-particle. For example, a graviton it its own anti-particle. If a graviton comes into contact with another graviton, they will annihilate. The same is true for photons. In fact, particle and anti-particle pairs constantly pop up into existence, separate, and annihilate with each other. This is demonstrated by the Casimir effect, conducted by Dutch physicist Hendrik Casimir. The Casimir effect is when an attractive forces arises between two uncharged plates due to the constant popping into existence and annihilation of particle-antiparticle pairs. One may think that this phenomenon of particle-antiparticle pairs violates the conservation of energy, which states that the total energy of a system always remains constant. However, the existence of these particle-antiparticle pairs is so short-lived that the average energy remains the same.
Symmetry and Quantum Gravity
Electricity and magnetism were unified by James Clerk Maxwell into what is called electromagnetism in 1873. This conclusion was drawn when Maxwell observed that electricity created a magnetic field, and an electric current would rise from the magnetic field. Then, another magnetic field would arise from this electric current, from which another electric current is produced, and so on and so forth. This phenomenon meant that electricity and magnetism could be unified into one single force. Maxwell came up with a number of equations to describe this unification. These equations described a symmetry between electricity and magnetism; that they were interchangeable. In fact, physicists Theodor Kaluza and Oskar Klein, keeping in mind the four known dimensions (height, length, width, and time), decided to add an extra fifth spatial dimension in an attempt to unify gravity and electromagnetism. They saw that gravity and electromagnetism became symmetrical in five dimensions, and they sent a letter to Einstein in 1919, requesting that their theory be published. Einstein was astounded by Kaluza and Klein’s result and mulled over the theory for two years in an attempt to comprehend it. He finally published the theory in 1921. This theory became known as the Kaluza-Klein theory, however, the theory had some major flaws due to which it had to be discarded. In spite of the failure of the Kaluza-Klein theory, it gave rise to one of the core concepts of string theory which is that the laws of nature become simpler in higher dimensions. Later, the Pakistani physicist Abdus Salam and the American physicist Steven Weinberg cam up with what is known as the electroweak unification theory. The electroweak unification theory unified electromagnetism and the weak nuclear force. Before the formulation of the electroweak unification theory, the weak nuclear force was not well understood. It was Salam and Weinberg who suggested that the weak nuclear force was carried by particles known as W and Z bosons. They later unified these W and Z boson with photons (which carry the electromagnetic force), saying that at high energies, all of these particles become symmetrical, but at low energies, they are distinct. Despite the greatness of this achievement, the ultimate goal of physics is to unify all four forces, attempts to do which have failed due to the incompatibility between general relativity and quantum mechanics. Physicists have been able to unify the electromagnetic force, the weak nuclear force, and the strong nuclear force. There are many theories which unify these three forces and there are known as GUTs (Grand Unified Theories). The name is misleading because the theory is not fully unified with gravity nor is it grand. The fundamental problem lies in unifying gravity (described by general relativity) with the other three forces (described by quantum mechanics). Whenever an attempt is made to unify gravity with the other three forces, the results produced are meaningless infinite answers. Perturbation theory (the theory of using approximations in calculation) also fails in unifying gravity.
Sources:
Hyperspace by Michio kaku
Physics of The Impossible by Michio Kaku
A Brief History of Time by Stephen Hawking
Abhijit Chavda
Subhash Kak
Random Thoughts 