The impossible is that which is considered to be unfeasible or unattainable. We cannot flap our arms and fly, we can’t hold our breath for hours underwater and we cannot see in the dark. Even though these feats are considered impossible to an ordinary human being, through the use of science and technology we human have conquered the skies, journeyed to the watery depths of the ocean and peered into the darkness of the night without the help of light (visible light to be exact). We have seen that as time goes on and technology becomes more and more advanced, science is able to blur the line between the impossible and the possible, turning science fiction into science fact. Dr. Michio Kaku, theoretical physicist and Co-founder of Grand Unified String Field Theory, uses his book “Physics of the Impossible” to demonstrate the underlying physics behind many of the “impossibilities” that today’s scientists toil over so that we may have a better understanding of which are realistically within the reach of our civilization.
From force fields to parallel universes and perpetual motion machines, Kaku divides the impossibilities that are throughout his book into three categories: Class I, II and III impossibilities. The first refers to “technologies that are impossible today but that do not violate the known laws of physics” and that might become possible in this century or the next. The second concerns those technologies that “sit at the very edge of our understanding of the physical world” and that might be possible in a thousand to a million years. Lastly, Class III impossibilities apply to technologies that “violate the known laws of physics” and that if possible, “would represent a fundamental shift in our understanding of physics.” Intrigued? I know I was. Such things had always caught my attention but I would dismiss them as just that, interesting queries that are ultimately meaningless because of their improbability. It was ignorant to do so, however. Even though Kaku makes the physics behind the impossibilities easy to understand, Class II and III impossibilities are very abstract and my limited knowledge in theoretical physics prohibits me in properly explaining them. As a result, I have chosen to explain the Class I impossibility that intrigued me the most: teleportation.
Teleportation is the capacity to instantly move objects from one place to another. Throughout this semester, we have journeyed through the world of Newtonian physics as objects move because they push and pull on each other. If an object wants to go somewhere, a force has to be exerted in order to move said object to the desired location. Makes sense, right? Well, there’s this thing called Quantum Theory and it doesn’t care much for your common sense. In Quantum Theory, particles like electrons can exhibit wavelike behavior as described by Erwin Schrödinger’s famous wave equation. It may sound weird but electrons can be described as waves of probability which “tell you only the chance of finding a particular electron at any place and any time.” This probability pertaining to electrons is known as the uncertainty principle which states that “you cannot know both the exact velocity and the position of an electron at the same time.” Therefore, in the strange world of the Quantum, it makes perfect sense for an electron to be at more than once place at a time and objects are described as the sum of all their possible states since there is no way to know for sure where its electrons are located. This might seem counter-intuitive since the physical world is full of objects that don’t spontaneously disappear and reappear such as our bodies. The human body however, contains trillions upon trillions of electrons and all the quantum events taking place inside our body even out over time giving it the appearance of being solid. Interestingly, if we were to calculate the probability of our body disappearing and reappearing in the next room, we find that we would have to wait “longer than the lifetime of the universe” to witness such a quantum event. This type of event is impossible under Newtonian physics yet is possible in Quantum theory, albeit the probability for it taking place is unimaginably small.
Einstein didn’t like probability and chance being introduced into the heart of physics once saying, “For my part, at least, I am convinced that [God] doesn’t throw dice.” He and two of his colleagues even performed an experiment in an effort to disprove Quantum Theory based on the idea of quantum entanglement. This is the concept that “ particles vibrating in coherence have some kind of deep connection linking them together.” This means that if two electrons are coherent, meaning they are vibrating at the same frequency, then what happens to one will affect the other regardless of the distance between the two since “there is still an invisible Schrödinger wave connecting both of them”. Not surprisingly, Einstein was unable to disprove Quantum Theory through quantum entanglement and ironically, it is this same concept that is the basis for teleportation.
Quantum teleportation is weird in the sense that an object doesn’t magically appear from one place to the other, rather its information is the one being “teleported”. To illustrate this, Kaku uses the example of three atoms A, B and C. Suppose we want to transfer the information from atom A to C; also suppose that B and C are coherent. If atom A comes into contact with atom B and becomes coherent, then A’s information is passed to B but since atom B was already entangled with C, then A’s information ultimately ends up in atom C. Strangely enough, if an object were to be teleported, it technically has to die before its information gets transferred to elsewhere creating the exact same object with the same information. It may sound weird but scientists have already been successful in teleporting particles in this manner. One of the most astounding achievements being the entanglement of a light beam with a gas of cesium atoms and teleporting this gas for about a half yard!
Teleportation involving entanglement might not be the as “science-fictiony” as one may had hoped but a way to teleport that is truer to the Star Trek tradition has already been discovered and therefore is called “classical teleportation”. It involves the use of a “Bose Einstein Condensate” or a BEC, one of the coldest substances in the universe. Some of the coldest temperatures in nature can be found in outer space ranging around 3 K above absolute zero (this is due to the residual heat from the Big Bang). A BEC however is “a millionth to a billionth of a degree above absolute zero”, a temperature only producible in a laboratory. BECs are important because at so low a temperature, atoms are at such a low state of energy that they vibrate in unison and therefore become coherent. Essentially, a BEC can be seen, as Kaku comically puts it, as “one gigantic super atom” since the wave functions of the atoms imbricate over one another. The first step in this method of teleportation involves shooting a beam of matter at a BEC where both consist of the same type of atom. As the beam comes in contact with the BEC, the beam’s atoms tumble down to the lowest possible energy state releasing energy in the form of light. Curiously enough, this light carries all the quantum information of the original matter beam so if then the light beam comes into contact with another BEC, a new matter beam identical to the original one is created.
Quantum teleportation is a technology that is deeply intertwined with that of quantum computers which are a new breed of computers that use the concept of quantum entanglement to make calculations. The reason today’s computers are so advanced is because their progress is based on the shrinkage of their components. Their components however cannot shrink beyond a certain threshold because then the uncertainty principle kicks in. Quantum computers are then the most likely candidates to replace their silicon based brethren in the near future. Besides all of the progress that has been made in this field, we are far away from having a personal quantum computer and teleporting ourselves to the mall. The most daunting obstacle is maintaining coherence between a large number of particles since the tiniest vibration is capable of causing decoherence. Quantum computers would require billions of constantly coherent particles in order to compete with today’s computers let alone how much it would take to teleport macroscopic objects such as a human being. Even though there are technical difficulties regarding teleportation, it is exciting to know that it doesn’t violate the laws of physics in any shape or form.
Einstein once said, “If at first an idea does not sound absurd, then there is no hope for it.” Making the absurd possible lies at the very pinnacle of scientific progress and it’s this absurdity which gives our civilization the potential for progress. Teleportation is just the tip of this magnificent iceberg and other even more exciting technologies might be hidden beneath the waves. Rightfully so, our future as a species may lie in the absurdity of such technologies.
Kaku, Michio. Physics of the Impossible. 1st ed. New York, NY: Anchor Books, 2009.