What is reality
Published: 05th February 2017
What is reality
The Lord God is subtle, but he is not malicious. Einstein, a remark made during his first visit to Princeton University, Apr. 1921
I have second thoughts. Maybe God is malicious after all
According to Valentine Bargmann, one of Einstein's collaborators, what Einstein meant was that God makes us believe we understand something when in reality we are very far from it.
These remarks reflect Einstein's lifelong discomfort with the principles of the new science, quantum mechanics. Einstein wasn't necessarily provincial or vainglorious, he, as we shall see also rejected crucial logical conclusions his own work unraveled. This, even after they were pointed out to him. Einstein's vacillations recall the words of Arthur Eddington, the British physicist and one of Einstein's most tireless champions: "Not only is the universe stranger than we imagine, it is stranger than we can imagine." One of history's most expansive minds was, almost paradoxically, unable to accept the boundless oddities of Nature.
After the mid 1920's the mainstream physics began to follow the course of the new quantum theory (and more recently String and Holographic Principles) a theory, which has often been described as breathtaking in its beauty and weird beyond that we can ever imagine. In Jim Al-Khalili's BBC documentary series about the basic building block of the universe, the Atom, Al-Khalili describes the world we think we know - the solid, reassuring world of our senses to be a tiny sliver of an infinitely weirder and more wonderful universe. More so than even we had ever conceived in our wildest fantasies.
Although quantum mechanics is an attempt to describe the behavior of matter and energy at the sub-atomic scale, it's utility has been vital in explaining aspects of stellar evolution, chemical reactions, and is responsible for the technological advances that make modern life possible. More fundamentally, it explains properties such as shape, color, texture, hardness and the way almost everything interacts and fits together. It underpins and encompasses everything from the biochemistry of life to why we can't walk through solid walls.
However, as predictions go, this theory is largely probabilistic - that is, even in the presence of exacting knowledge, say of a falling raindrop, it is impossible to predict its future definitively regardless of how much care we take in such a prediction. Einstein, arguably the most revolutionary thinker of modern times struggled greatly with quantum mechanics. He became the most prominent critic of the new theory believing the way ahead for fundamental physics was to develop the geometrical approach of his general relativity theory (a unified theory of space, time and gravitation) into an all encompassing unified theory within which the results of the new quantum theory would be derived. Some call this a "theory of everything", others more enthusiastically, "a final theory". And, Einstein as if seeking to further legitimatize his viewpoint more than once spoke for his God; I am convinced, he said, that "He does not play dice", and "whoever undertakes to set himself up as a judge of truth and knowledge is shipwrecked by the laughter of the Gods."
According to one author Einstein was searching for a theory that not only reconciled general relativity to quantum mechanics, but it reconciled Science and the Bible as well - an undertaking by anyone's reckoning.
The new science doesn't just demand us to rethink lofty concerns such as the shape and size of the universe, space and time, or of the role subatomic particles may play in co-creating multi-worlds and multi-histories, or even whether a Prime Mover is needed at all, but also how the consciousness of human agents enters into the structure of physical phenomena. The principles of quantum mechanics contradict the older idea that local mechanical processes alone can account for the structure of all observed phenomena. The new science brings directly and irreducibly into the overall causal structure certain psychologically described choices made by human agents about how they will act.
Our experience tells us that our reality is made up of physical material, and that our world is an independently existing objective one. However, according to the new science reality is far beyond human perception and most certainly intuition. We have difficulty explaining consciousness in terms of material as chemical and physical processes. How for example can the interaction of physical objects give rise to something as immaterial as experience, emotion, or feeling? It is conceivable that consciousness and reality are not as separate as material science would have us believe. And from this comes a shocking truth that may force us to rethink the nature of reality itself.
Quantum mechanics teaches us that the way subatomic particles such as Quarks, Gluons, and Photons behave and interact is fundamental to the way the universe works. Indeed, the "Standard Model" of particle physics, the theory that describes the behavior of subatomic particles is currently the most accepted theory of the universe. For this reason it is sometimes regarded as a "theory of almost everything". And, it is because of this preeminent status that subatomic particles need not submit to our everyday sensibilities. Amit Gozwami in his 1993 book, "The Self-Aware Universe" sketches out some of their more enigmatic peculiarities.
Subatomic particles can be at more than one location at the same time. They cease to exist here and simultaneously appear over there without traveling the intervening space. Pressing one subatomic particle by a conscious mind simultaneously influences its correlated twin particle, no matter how far apart they are. Subatomic particles are not located in ordinary space and time until they are being watched.
Gravity's lingua franca
As mentioned, Einstein spent the second part of his life trying to develop a complete theory that would at last unify his theory of general relativity with quantum mechanics; that is, reconcile the large-scale structures of the universe with the very small. And, although this work would engender intense skepticism there was much reason for Einstein's doggedness and resolve. After all, general relativity is regarded a basic theory for all of physics, and one of the greatest intellectual achievements of the twentieth century. It is also one of the most audacious ideas of modern science, quite literally giving the universe order, shape and structure.
It is astonishing in its reach. If we imagine our planet as a speck of sand amongst a billion other granules of sand on a tiny and relatively unremarkable stretch of land, and we are looking out at the universe off this unassuming dot we call home, then not only does this theory tell us something about our own neighborhood of mud, but about all neighborhoods found on all stretches of land in all the world.
Einstein's notion of space-time isn't something that can be grasped intuitively; we can't, for example, see it when we look up at the skies. We can't feel it when we drive around town. The theory relies on a great deal of advanced mathematical structures and techniques. In fact, until very recently, general relativity was taught only in postgraduate mathematics or physics courses, because the mathematical foundations of the theory were regarded as much too demanding for undergraduate students.
Nevertheless, it is useful to try and get some sense of this breakthrough. The significance of this theory can be appreciated when we survey prevailing tenets vis-à-vis gravity at the beginning of the twentieth century; those tenets Einstein miraculously overturned at the tender age of 26. To do this we must first go back some 350 years; to a time when Great Britain and greater Europe were gradually emerging out of the shadowy Middle Ages, the age of faith and now, with greater hast entering the so called age of reason.
God the divine watchmaker
Changes in philosophy and science ensued quickly and natural philosophers such as the great Newton, Galilei and Harvey began to be understood as scientist. The intrusion of newly invented machines became part of the daily and economic lives and the science of chemistry developed from medieval alchemy, and the 17th century science of astronomy evolved from astrology.
Profound religious beliefs gave way to scientific reasoning and staple creationism began, slowly at first, to revel itself as inherently mechanical and predictable - prompting Newton to call God "the Divine Watchmaker". This of course didn't happen without resistance. Theological arguments' (particularly confessionalistic) opposition to accepting change continued to exert a powerful influence on the vision of the world and the interpretation of Nature, even if the two worlds, that of faith and that of science, were slowly separated.
During a period of much ideological change Newton formulated his famous law of universal gravitation - arising it is said from an astonishing piece of insight. He compared the acceleration of the Moon to the acceleration of objects on Earth (a fable tells of an apple falling near where he was resting). Believing that gravitational forces were responsible for each. For the first time a physical law, moreover a product of man, seemed to completely describe the influence of gravity here on Earth and elsewhere.
And, whilst Newton acknowledged a monotheistic God as the masterful creator whose existence could not be denied, he apparently didn't see contradictions between religion and his science. They simply further maintained that while the natural world operates without the direct intervention of God, his existence, along with that of human beings, is part of a larger teleological plan that reflects his intent.
According to Newton every object with mass exerts an attractive force on every other object. The magnitude of the force is inversely proportional to the square of the distance. Although Newton never provided an explanation for gravity, he most certainly gave us a means to make sense of, and calculate the motion of things [affected] by gravity - all things; cannonballs, footballs and as mentioned celestial bodies too. In fact, Newton's work has served us well - its utility has enabled the launch of countless satellites, track icy comets, and even fly man to the Moon.
And about the same time in Germany scientific psychology began as a physiological psychology born of a marriage between the philosophy of mind, and the experimental phenomenology that arose within sensory physiology. Philosophical psychology, concerned with the epistemological problem of the nature of knowing the mind in relationship to the world as known, contributed fundamental questions and explanatory constructs; sensory physiology and to a certain extent physics contributed experimental methods and a growing body of phenomenological facts.
In 1690 John Locke distinguished between primary and secondary qualities. Primary qualities, he believed, such as solidity are completely inseparable from the bodies in which they inhabit. These, according to Locke are perceived by our senses. Secondary qualities are powers inherent in objects to produce sensations in the perceiver such as color, odor, or sound. Interestingly, these qualities did not themselves exist in objects. Locke and others tried to ambush problems of perceptual illusion by distinguishing between the material objects and the ideas by means of which we perceive them.
George Berkeley, the Bishop of Cloyne on the other hand proffered that this representationalist approach can provide no reliable account of the connection between the qualities (ideas) and the objects they are supposed to represent. A God was still involved in Berkeley's immaterialistic philosophy. Locke's notion of secondary qualities was now expanded to include primary qualities and taken out of objects and placed in both God and, for the first time the mind.
So as far back as the late 1600's, the so-called defender of common sense, Berkeley held that what we perceive really is as we perceive it to be. However the things we perceive are just sensible objects, collections of sensible qualities, which are themselves nothing other than ideas that exist within our minds. Something that quantum mechanics re-invokes, albeit minus the role of God. For instance, Fritjof Capra, the author of The Tao of Physics (1975) and The Hidden Connections (2002) writes: "The crucial feature of atomic physics is that the human observer is not only necessary to observe the properties of an object, but is necessary even to define these properties.
God the substance par excellence
For many philosophers of this period the universe, at the very deepest level, contained only two categories of entity: substances and modes. Modes are synonymous to Locke's secondary qualities. But ultimately all modes exist in something which is not itself a mode, that is, in a substance.
Given the foundational role substance played in the metaphysical schemes of most thinkers of the time it is not surprising to find that theories of substance underlie dramatically different accounts of the nature and structure of reality. The existence of God on the other hand was not only a given but God's existence was absolutely independent of all substance - the ultimate independent being, God the substance par excellence. And this wasn't necessarily just a 17th century conception. In the second half of the 4th century BC the treatise by Aristotle talk of only three kinds of substances; God, heavenly spheres, and animals and plants.
My greatest blunder
In 1924 Edwin Hubble working at the Mount Wilson Observatory in Los Angeles discovered that stars in Andromeda were at least ten times farther away than the farthest stars in our Milky Way. He announced to the world that the Andromeda nebula was really the Andromeda galaxy. This discovery had, instantly, transformed us and our place in the universe. Other, even fainter spiral objects were now probably also distant galaxies, other worlds.
Our galaxy that was once considered the whole, the entire universe just became another amongst, based on current estimates over 500 Billion. So important was this observation that many could not resist the temptation to connect this news with the existence of other life, extraterrestrial life. A search of the Associated Press Archives unearths remarks such as; "In essence, Mr. Hubble Reveals We Are Not Alone."
And just five short years later, in 1929 Hubble, by all accounts still the stubborn, ambitious, and sometimes even snobbish young man finds evidence for the idea that the universe is in fact expanding, and expanding at an accelerating rate. In the same year, Einstein, his face yellowish, haggard, nervous, and irritable was on the front cover of Time magazine, his accomplishments further recognized - receiving the German Physical Society's first Max Planck Medal. Sometime later, the exact date remains unclear, he is said to have remarked that adjusting general relativity to stop the universe from expanding was his "biggest blunder of his life." If only he knew the half of it.
Holes in space and time
Despite the momentous accomplishments Newton achieved it took the genius of Einstein to pull back the cloak behind which hid the stuff of the universe. Features that had gone largely unnoticed since man first gazed at the stars. Einstein realized that Newtonian gravity was just an illusion and that it is space itself that is distorted. When we look at a distant star, trusting that it is directly overhead, we never suppose that the path of light coming to us from that star is following the contours of a curved space (and time). To us, it always seems like it is following a straight line. This understandable, however, parochial view is somewhat analogous to an insect stuck on the surface of our curved planet. It is unable to stand back far enough to see the curvature for what it is. We can't see Einstein's curved universe from the inside.
General relativity proposes that space and time dimensions are interchangeable and massive objects cause a distortion in space-time. Imagine setting a large body in the center of a trampoline. The body would press down into the fabric, causing it to dimple. A marble rolled around the edge would spiral inward toward the body, pulled in much the same way that the gravity of a planet pulls at rocks in space. John Archibald Wheeler said it best in Geons, Black Holes, and Quantum Foam, "Space-time tells matter how to move;" and "matter tells space-time how to curve."
When Einstein published his theory it was assumed that the universe was made up of stars whose distribution was relatively uniform throughout space. Also, as mentioned the overall size of the universe was static. Einstein himself knew that having a uniform distribution of matter would be problematic. He reasoned, if space-time is going to curve due to the presence of matter then those regions of space-time with more matter are going to preferentially attract more and more matter, thus forming regions of intense gravitational fields or Black Holes! Einstein dismissed the existence of holes in space, perhaps foretelling what a mess the math would be.
Einstein once described himself as a "deeply religious nonbeliever." By such a statement he meant that his worldview was somehow pervaded by an overwhelming and general feeling of religiosity rather than dominated by some specific creedal commitment.
Perhaps Einstein's curiosity in the Eucharist might be easier to fathom were we to regard it as a symptom of his abiding and lifelong quest to unravel the eternal enigma of appearance and reality. Relativity theory, in its special and general forms, and, even more iconoclastically, quantum mechanics as we shall see, together caused a complete revolution in human understanding of the physical world, the consequences of which are still to be absorbed into philosophy-and hardly yet into theology.
According to John Pilbrow, in The Impact of Einstein‘s Relativity on Christian Thought, relativity and Christian thought is a topic that isn't new. Indeed, not unlike the state of affairs of the 17th Century, a love-hate relationship between theologians and relativity, particularly in the 1920‘s and 1930‘s, endured. Anti-Semitic objections to Einstein's Jewish heritage occasionally played a role as well, as did alleged errors in the theory, rejection of an abstract-mathematical method, and misunderstandings.
Let there be light, and there was light
Had Einstein not adjusted general relativity to stop the universe from expanding, his theory would have predicted not only an expanding universe, but also, a universe that ascended from a single point of infinite density, infinite temperature at a finite time in the past. The birth of the universe is estimated to be 13.7 billion years ago.
Ironically, a Belgian priest, Monseigneur Georges Henri Joseph Édouard Lemaître was the first person to propose the idea of the primeval atom in 1927, now better known as the Big Bang theory. Briefly, this theory is an attempt to explain the very beginning of our universe, before which there was no space and no time. Accordingly, the universe sprang into existence as an infinitesimally small, infinitely hot, infinitely dense, energy state - a singularity. The idea that there was no time before the Big Bang isn't new. Augustine reached a similar conclusion 1500 years earlier. When, he said "the world was not, there was no time."
Whilst the earliest phases of the Big Bang are subject to much speculation the most common models suggests that approximately 10−37 seconds into the expansion, a phase transition caused a cosmic inflation, during which the universe grew exponentially. Over time the temperature and density of the universe gradually diminished. When the universe was just 500 million years old, slightly denser regions of space-time attracted nearby matter and became even denser. This leading to the forming of gas clouds, stars, galaxies, and other astronomical structures observable today.
In the beginning, according to Genesis, God said, "Let there be light," and there was light. God saw that the light was good, and he separated the light from darkness. Big Bang on the other hand, predictably, offers a more precise account of light and darkness. Until around 400 million years after the Big Bang, the universe was a very dark place. As the universe expanded, the hot soup of fundamental particles (such as free protons and electrons) started to cool down. This allowed electrons and protons to pair up and form neutral hydrogen atoms. As free electrons were now bound to protons, light could travel freely since frequent scattering off free electrons no longer was an impediment, thus giving rise to the universe's first dawn.
An important matter is the future of the universe. Does the universe have an eschatological purpose? Or what kind of future is there? Ted Peters, in his 2003, Science, theology and ethics puts it this way: "Big Bang cosmology opened the window within science toward transcendent creation in the past while apparently closing the window to redemptive eschatology for the distant future."
Observations suggest that the expansion of the universe will continue forever. If so, the universe will cool as it expands, eventually becoming too cold to sustain life. For this reason, this future scenario is popularly called the Big Freeze.
Nobody understands it…
Einstein was never happy with quantum mechanics. One of the main reasons was because it denied a reality of things when they were not being observed. He particularly disliked the loss of determinism in measurement. Despite his assiduous persistence to reconcile quantum mechanics with general relativity and remedy what he considered an incomplete theory, he passed away in 1955 at the age of 76, still not accepting quantum mechanics. Should quantum mechanics not have enjoyed remarkable empirical successes Einstein could have brushed it aside.
There was good reason why Einstein couldn't just discount quantum mechanics. The theory is among the most stringently tested in physics and has enormous success in explaining many of the features of our world. It is often the only tool available that can reveal the individual behaviors of the subatomic particles that make up all forms of matter. Importantly, this theory has provided a coherent basis for the development of the more topical String theories, candidates for a theory of everything.
However reliable and useful quantum mechanics has been, it has more than any other theory, challenged any reasonable worldview. It actually denies the existence of a physically real world independent of a conscious mind, an observer. It also tells of a strange entanglement that quite simply can't be understood in terms of the everyday world. The great Richard Feynman once exclaimed, "I think I can safely say that nobody understands quantum mechanics."
Deep in the bowels of quantum mechanics subsists physical uncertainty - the Heisenberg uncertainty principle states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa. The same is also true for time and energy. So for instance, let's imagine that we are looking inside a box that contains absolutely nothing - a total vacuum. If we now stretch the minutest interval of time (i.e. slow time down) then the Heisenberg uncertainty principle tells us that as we reduce the interval of time we begin to loose precise information about the exact amount of energy in the box. If we continue to reduce the interval of time and at the same time focus our attention on smaller and smaller section of space in the box then this principle predicts something truly bizarre. We would be so uncertain about how much energy is in that part of the box that there is a chance that it could contain enough energy to create particles literally out of nowhere. Feynman, in his Quantum Electrodynamics (QED) theory predicts that this energy is not from nowhere but instead could be from the future.
So by our free choice we could demonstrate either of two contradictory physical realities. We can, for example, demonstrate an object to be someplace. But we could have chosen to demonstrate the opposite: that it was not in that place. Observation created the object's position. Quantum mechanics has all properties created by their observation.
The perspicacity of the uncertainty principle can be appreciated when we ask the question; is our knowledge of reality unlimited? The answer is no, because the uncertainty principle states that there is built-in uncertainty, indeterminacy, and unpredictability to Nature. Einstein's disdain once again, "as far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality."
So a universe born out of a "primeval atom" and driven largely by probabilistic fluctuations has, amongst other things, prompted some to ask; shouldn't an omnipresent God, for example, know the exact location and velocity of every particle in the entire universe? It must be said, perhaps, judgments about a "divine God" can not be based on what is, probably still a very primitive knowledge of the Nature. Einstein, himself believed in Spinoza's God who reveals himself in the orderly harmony of what exists, not in a God who concerns himself with the fates and actions of human beings.
Quantum mechanics, and in particular the uncertainty principle has also been used to guide a range of a psychologies and perception models. Gestalt psychology, for example, was popularized in the early 20th century to account for interference effects obtained with measurements of ambiguous figures. This psychology tries to understand the laws of our ability to acquire and maintain stable precepts in a noisy world, arguing, "The whole is other than the sum of the parts." A good example to help us make sense of this is to think about something we have all been fascinated with at one time or another. Cognitive illusions, particularly visual illusions characterized by visually perceived images that differ from objective reality. Escher's drawing of a waterfall is a good example. Here, the 1961 illustration shows an apparent paradox where water from the base of a waterfall appears to run downhill along the water path before reaching the top of the waterfall.
Many, including David Bohm, expound the notion that mind and matter both emerge from an "implicate order", have pointed out similarities between Gestalt phenomena and quantum mechanics. Outcome of two measurements performed one after the other involving human perception can depend on the order in which they are performed - a pertinent feature for psychological processes.
Those working in the field of quantum mechanics regularly submit to the bizarre denouements the theory postulates, confessing, albeit nervously to the shocking nature of reality.
And there are compelling reasons for some reservation. Underneath the seemingly familiar world lies a kind of a foam; a "quantum foam" made up of particles that are created from nothing and from nowhere, and that's just for appetizers. The exceedingly precise Quantum Electrodynamics (QED) theory mentioned earlier flies in the face of much of our common sense ideas. One example is that of emptiness and nothingness. Emptiness, such as that we expect to find in a vacuum is after all a place where nothing exists and nothing happens. Isn't it? It turns out that the vacuum isn't empty; on the contrary it is in fact full of stuff and is heaving with activity.
According to QED empty space can borrow energy literarily from the future. This energy is used to create a pair of particles; a particle and an antiparticle, that are spontaneously formed from the void before annihilating each other; all almost instantaneously. So energy is borrowed out of nowhere, it's turned into matter, matter than self-destructs back into energy. And from this comes the most jaw-dropping idea of all. QED purports that the matter we think of as the stuff that makes up the everyday world, the world that we see and feel is basically just a kind of a left over from all the feverish activity that these particles get up to in the void.
In the mid 40's, about when the QED theory was being refined and fully developed by Richard Feynman and his collaborators, two Dutch physicists, Hendrik Casimir and Dirk Polder were working on fluid properties at the Philips Research Lab. Trying to understand why colloidal solutions like mayonnaise and paint move so slowly they came to realize that an entirely different force was needed to explain this phenomenon.
Casimir noticed that this result could be interpreted in terms of vacuum fluctuations - the same vacuum fluctuations QED predicted. Instead of theorizing about how molecules that make up colloidal solutions interact, Casimir asked what might happen if two mirrors are arranged to face each other in a vacuum. It has since been shown that when two uncharged metallic plates (mirrors) are placed near each other, within a vacuum, something quite unexpected takes place, now called the Casimir Effect. Particles created out of the void where nothing is supposed to exist are able to push the two plates together. The Casimir Effect is another result of quantum mechanics that seems to defy the logic of the everyday world. In this case energy is created from empty space and exerts a force on the physical world.
This "spooky" science
The theory of quantum mechanics predicts that two or more particles can become "entangled", a term coined by the Austrian physicist Erwin Schrödinger, so that even after they are separated in space and time. An action on one particle triggers an immediate response on the other. This might at first seem inconsequential but for the word "immediate". It doesn't matter how far apart these particles are, indeed they can be at opposite ends of the known universe, and yet the particles seem to retain an immediate and fundamental connection with each other. What's more, we haven't the slightest inkling how this works.
Now this idea is bizarre by anyone's account. This prediction, which incidentally has been shown to be true in numerous experiments, riled Einstein so much he called it "spooky action at a distance." Advocates of "local realism" by which the classical world is governed refer to several "loopholes" in order to save their world-view. Local realism is a world-view in which the properties of physical objects exist independent of whether or not they are observed by anyone (realism) and in which no physical influence can propagate faster than the speed of light (locality).
If it turns out that any remaining loopholes are exhausted and entanglement continues to become an increasingly accepted part of our physics in a similar way we accept that nothing can travel faster than light, then we must accept at least one of the following radical views: there are hidden faster-than-light conduits in Nature or we indeed live in a world in which physical properties do not always exist independent of observation. My own work and interest in guiding waves brands me a proponent of the hidden variable school - and elements of reality might overtime be incorporated into quantum mechanics.
Quantum mechanics also continues to challenge religious doctrine, as well as established philosophies constructed over many hundreds of years. Realist, for instance, have sought to defend against philosophical paradox and scepticism since the 18th century. Further back, Plato described mathematical and ethical realism. They maintain that ordinary experiences provide intuitively certain assurance of the existence of the self, of real objects that could be seen and felt and of certain "first principles" upon which sound morality and religious beliefs could and have been established.
In the 2011 novel The Entangled God, author Kirk Wegter-McNelly draws on recent scientific and philosophical work in quantum entanglement to develop the metaphor of "divine entanglement" providing a scientifically informed account of the God - world relation. Here, he introduces theological and religious readers to the fascinating story of quantum entanglement.
The granddaddy of all
Richard Feynman once described the "double-slit" experiment as the central mystery of quantum mechanics. He then corrected himself saying that in fact "it is the only mystery." Still later "if you understand this, you would understand quantum mechanics."
If you think Feynman was someway gloating he was not. It was not his way. On the contrary, Feynman insisted that neither he nor anyone else truly understood quantum mechanics. This is a remarkable admission. You see, Feynman was no common-garden-variety genius - it's said often that he was the last true genius of our time. A Nobel Prize - a part of the course. Larger than life, ebullient, brilliant, and irreverent; Feynman at the age of 30 advanced one of the most complex and complete theories of everything, QED the jewel of physics. This theory describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved.
Together with gravity, QED explains almost all of our everyday experiences and observations. It explains why there are a finite number of elements in the universe. It unifies the description of matter with electromagnetic radiation. It describes the properties of everyday objects including, their shape, color, texture, their transformations and their changes. The reason why this theory intrudes so much into our everyday world is for the fact that subatomic particles such as protons and electrons are 99.99999% empty space. "Reality" is not simply made of tiny physical particles as we came to learn at school. We interact with a world of physical objects but these are really just electrical signals being interpreted by the brain as objects with substance. At the smallest and most fundamental scales of nature, the idea of "physical reality" is non-existent.
So when Feynman said he didn't understand quantum mechanics we can take that as signal warning us just how curious things are. He was also fond of saying that all of quantum mechanics can be gleaned from carefully thinking through the implications of this single experiment, the double-slit experiment.
In the double-slit experiment, light is shone at a solid thin plate that has two slits cut into it. A photographic plate or some other detection screen is set up to record what comes through those slits. One or the other slit may be open, or both may be open.
Normally, when only one slit is open, the pattern on the plate is a diffraction pattern, a fairly narrow central band with dimmer bands parallel to it on each side. When both slits are open, the pattern displayed becomes very much more detailed and at least four times as wide. When two slits are open, probability wave fronts emerge simultaneously from each slit and radiate in concentric circles. When the detector screen is reached, the sum of the two probability wave fronts at each point determines the probability that a photon will be observed at that point. The end result when many photons are directed at the screen is a series of bands or "fringes."
When two slits are open but something is added to the experiment to allow a determination that a photon has passed through one or the other slit, then the interference pattern disappears and the experimental apparatus yields two simple patterns, one from each slit. However, interference fringes are still obtained even when only one slit is open at any given time.
The most baffling part of this experiment comes when firing single photons at a time and ensuring that they reach the screen one at a time the same interference pattern is obtained in the end. Amazingly enough, if one of the slits is closed or opened particles seem to be able to acquire this information somewhere during their journey from the source to the screen and the interference pattern brakes up or is formed accordingly.
No single history
Feynman's explanation for the double-slit experiment is equally confronting, daring (and if not for Feynman probably also insane) scheme called sum over histories. Here, Feynman suggests that particles being fired towards the barrier do not just take a single path from the source through one or the other slit until they reach the screen. Rather they take all possible paths to travel from the source to the screen, and that all these paths are taken simultaneously.
All possible paths means just that! Once these particles leave their source they can take a voyage of discovery via Long Island, get squeezed in Abbott's Flatland, and even taste your morning coffee before eventually passing (or not passing) through one of the slits. And from this comes a gift that Science Fiction authors have exulted since the days of Verne and Wells - the "many-worlds" interpretation. This interpretation of quantum mechanics suggests that all possible alternative histories and futures are real, each representing an actual "world" or even "universe".
Clearly, reality, for us has always been a single unfolding history. Many-worlds on the other hand portrays reality as a many-branched tree, wherein every possible quantum outcome is realized. Stephen Hawking and Leonard Mlodinow in their 2010 Grand Design argue that it is unnecessary to invoke God in order to explain the origins of the universe. After all, their reasoning goes "If the origin of the universe was a quantum event, it should be accurately described by the Feynman sum over histories." Here the authors are using sum over histories as an example to illustrate how you might apply the philosophy of Science to the beginning of the universe.
Hawking's lost intelligence
Stephen Hawking shot to fame when he provided a mathematical proof for the Big Bang theory after realizing that the universe was, in effect, a black hole in reverse. In the early 1970s to the early 1980s, the golden age of black hole research, Hawking came to understand that black holes actually radiated out energy. This was not supposed to happen. Orthodoxy maintained that nothing should be able to escape the gravitational grip of a black hole. Yet, Hawking's idea was shown to be correct. What's more Hawking also claimed that over time, because of this leak, black holes would eventually evaporate and finally disappear.
But a disaster lay silently in wait. A problem Hawking had to have known about for almost 30 years. In 1976 he published a paper called 'The Breakdown of Predictability in Gravitational Collapse'. In it he argued that it wasn't just the black hole that would eventually evaporate away but the information about everything that had ever been pulled into the black hole would vanish with it. If, for example, I were to be drawn into a local black hole wearing a blue cap later today - all information, including the color of my cap would be lost. This, however, is at odds with what is known to exist in both classical and quantum physics. The conservation of information is a deep physical principle stating information cannot appear or disappear.
For many years no one really took much notice of Hawking's ideas until a fateful meeting in 1981 during an informal meeting of eminent physicists at the mansion of the New Age self help guru, Jack Rosenberg. As stories go it turns out that the backstory alone would make a compelling Hollywood tail. Jack was a super-salesman, and a con man. Prior to the early 1970s, he had been just plain Jack Rosenberg, encyclopedia salesman. It's said that one day, while crossing the Golden Gate Bridge, he had an epiphany. He would save the world and, while he was at it, make a huge fortune. All he needed was a classier name and a new pitch. His new name would be Werner Erhard; the new pitch would be Erhard Seminars Training, aka EST - I digress.
Gerad t'Hooft and Leonard Susskind where also at Jack's place, listening to the now celebrated Hawking when they both realized that Hawking's "breakdown of predictability" applied not only to black holes, as Hawking intended but to all processes in physics. If information really was lost forever within black holes, one of the key principles holding quantum mechanics together, information conservation, would be violated. According to Susskind, if Hawking's ideas were correct then it would infect all physics, there would no longer be any direct link between cause and effect. Physics would become impotent.
Since that meeting the "information paradox" has become one of the most fundamental and most difficult problems in physics. Arguments effectively boiled down into two camps. On the one side were Susskind and those who believed that Hawking was wrong: information could not be lost. On the other were Hawking and those who believed that physics would have to be rewritten to take into account the uncertainty about information that Hawking had uncovered.
In 2004, Hawking conceded. He was in error! Information is not lost when a black hole is no more. Hawking's "mistake" was one of the most seminal in the history of physics and could ultimately lead to a profound paradigm shift about the nature of space, time and matter.
Leonardo Susskind, a straight talking and card-carrying atheist began working as a plumber at the age of 16, taking over from his father who had become ill. Scientific American magazine called Leonard Susskind: The bad boy of physics who rebelled as a teen and never stopped. In the early 80's he co-founded string theory, that over time has become the leading candidate for a unified theory of nature. And then in 1994 Susskind and Hooft developed what is now called the Holographic Principle. Here's where things get interesting. According to Susskind and Hooft when objects fall into black holes the information associated with that object isn't lost but resides on the surface of a black hole as viewed from outside of the event horizon. Information in the immediate vicinity of the black hole is mapped onto its surface. From this comes the mind-blowing idea that the surface of the black hole is a holographic projection of all things in its vicinity.
When living in truly interesting times, we expect the truly unexpected. Many now think that this idea should not end with black holes. Some think that information about ALL things; is spread across the far edge of the universe. The universe therefore is nothing more than a projection of a holographic film. Whether we actually live in a hologram is, with good reason, being hotly debated. Having said this, it is now becoming more and more clear that looking at physical phenomena through a holographic lens could be key to solving the greatest riddle of all - us!
For now I am reminded of the Corinthians 15:51 - Behold, I tell you a mystery; we will not all sleep, but we will all be changed.
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