An extended essay I wrote back in 2012 on how concepts in modern physics imply counterintuitive truths regarding the nature of reality.
Part I: The Philosophy
It’s one of the simplest yet most profound questions in science: what is the true nature of reality? Reality is a concept so fundamental, one of which humanity has produced what could be seen as a socially constructed consensus of, quite simply, the way things are and the state of the world around us. Of course we can just treat reality as this, a way of summarising the nature of our surroundings, our perception, deduction and understanding, then continue with our daily existence, content with what we have concluded. Perhaps “reality is nothing more than agreement or “collective hunch” that people have arrived at to make life more livable.” However, recent scientific developments and their capacity to probe our surroundings have begun to dig deeper, past what our senses alone have allowed, helping to unveil the hidden nature of reality. Where it seems sensory experience is deceptive and our built up repertoire of common sense itself is no guide. Perhaps, the apparent illusion of everyday reality may never seem the same again.
Attempting to describe reality is the ultimate fusion of philosophic and scientific thought. In this essay I hope to begin by outlining the history of thought concerning reality and how the first attempts to judge its character came about, the era prior to the truly scientific age. Two important branches of philosophy concerning this, being; Metaphysics is the study of fundamental nature of reality, tackling issues of being and existence whilst the second being epistemology, questioning how we acquire knowledge and judge our findings.
It is then mainly the developments in 20th century physics that shall be the focus, discussing the areas of relativity, quantum mechanics; string theory, dimensions and parallel universes, and the drastic implications these have had on viewing reality, and the newfound, resulting quantum reality.
The concept of reality has developed over the times, since the early Greek philosopher Thales, who believed that the source of everything came from water, people have tried to seek the truth of what is real and how everything came to be. A particular approach to reality known as Dualism views that there are two ultimate sorts of stuff, mind and matter, the analysis of these two subsections also referred to as materialism and idealism. Materialism states knowledge comes from perception alone; we understand reality through direct observation. Idealism however denies the existence of matter and instead holds that everything there is, is mental or spiritual. The key prevailing theme here when philosophy attempts to tackle reality is the relationship between the mind and reality itself. If the existence of reality is independent of beliefs or perception, the theory known as realism stands. One can identify and classify objects, their existence and essence exist independent of an observer. However there are cases which present an anti-realist standpoint, one of the first being idealism. The view of idealism propounded by Berkeley portrays reality as a product of our ideas, created in the mind. For example, when an object is observed, what one is really aware of is not how the object is itself, but how the object looks to oneself. Thereby not describing the object but state of consciousness the object produces in oneself when looked at it, as if the objects are actually internal ideas produced by ones perception.
These two schools of thought belong to the branch of metaphysics, attempting to judge what sorts of things there are. Dualism advocates that over and beyond the physical reality there is a psychic or spiritual reality, and our beings are not limited to the body alone. Of course when entering the realm of a higher spiritual reality, religion branches forth presenting its own ontological doctrine and dependent on the path chosen to venture down the components of reality can alter a lot indeed.
Epistemology similarly has opposing branches, empiricism and rationalism. This essentially makes a distinction between perceiving and thinking. In an empiricist viewpoint of reality, what we perceive can be interpreted as truth. The empiricist standpoint emphasizes the role of experience and evidence, especially sensory perception. It is fundamentally linked to the scientific method, that theories about reality must be tested against observations of the natural world. A root of this being Positivism, principally founded by Auguste Comte, the idea that science and scientific method represent the best way to uncover the pathways through which physical and mental processes occur. Whereas rationalism is a view appealing to reason, that deductive reasoning is the source of knowledge or justification. It is a theory “in which the criterion of the truth is not sensory but intellectual and deductive” (Bourke 263) the rationalist standpoint is that reason has precedence over other ways of acquiring knowledge. The French philosopher Henri Bergson, repudiated the theory of positivism as he embraced a more skeptical perception of science as an answer to the metaphysical questions of the world. He forwarded the idea that to understand reality, one need only follow one’s intuition as opposed to science and rationalism in order to comprehend the true nature of reality.
Thereby rationalists tend to argue that the appearance of the world is an inadequate guide to the world’s reality. The apparent true reality of the world is presented to reason, through thought and argument that resolves the vagueness of mere sensory perception. The world as it appears to the senses may therefore be entirely misleading, an idea we shall indeed follow up on in the quantum realm.
Empiricists argue that in perception we are in contact with the world around us and they are influencing our being. Furthermore, the empiricists criticism is, if we attempt to think independent of perception, what link do we have to the world upon which we are attempting to contemplate? Yet a troubling question for empiricists lies with the differentiation between appearance and reality. We are in need for some criterion to distinguish truth from sensory perceptions alone which could be illusory. Berkley’s premise is that knowledge comes to us only through experience, so if no criterion for the reliability of experience exists how can we be sure that we have any grasp of reality at all.
The idea of reality is often interpreted as a uniform framework for all within it. However, if reality is thought to be based upon perception and deduction, can we be entirely sure this uniform structure exists, and perception is not truly a subjective matter? Yet we still attempt to produce a shared and public theory, designed to explain and predict the way things appear, by attributing common qualities to objects via relation. When describing the world, we assume (hopefully) that it exists independently of those who perceive it. That the grass really is green, regardless of how it appears to me or that the moon really is there when no one looks at is (a question we shall return to later with the help of Einstein.)
Can we become lost in illusion and naïve to true reality when relying upon sensory experience and perception?
“Lao Tzu fell asleep and dreamt he was a butterfly. Upon wakening he asked, “Am I man who has just been dreaming he was a butterfly? Or a sleeping butterfly now dreaming he is a man?”
Descartes in the 17th century in his Meditations produced the “dream argument,” the postulation that the act of dreaming provides preliminary evidence that the senses we trust to distinguish reality from illusion cannot be entirely relied upon, and therefore, any state that is dependent on our senses should at the very least be carefully examined and rigorously tested to determine if it is in fact “reality.” As, when people dream, they enter a state of naïve consciousness where they do not believe they are in a mind simulated framework, instead the dream acts as their temporary reality and it is only upon waking that it is realised what was experienced was only a trick of the mind. With this vivid creation of reality that our senses succumb to within our own minds, is it plausible to suggest that we still may be in a dream state, not yet enlightened to the “real world” that exists in the next level of awakening.
“Whatever I have accepted until now as most true has come to me through my senses. But occasionally I have found that they have deceived me, and it is unwise to trust completely those who have deceived us even once.” Descartes
How well grounded and credible is our ability to distinguish between reality and appearance, when our knowledge of what we perceive to be reality comes from previous judgment alone. But if we base our views upon rationalist thought surely we must advance to a viewpoint outside that of common sense or experience and upon what basis can we seek this. The attempt to quantify reality often leads us round in circles.
Part II: The Physics
“Reality is merely an illusion, albeit a very persistent one.” Einstein
The first scientific revolution which affects reality that we shall explore is that of time and relativity. Human activity relies heavily upon the construct of time; our outlook on reality and the way in which events unfold and the state of the world around us are woven to the passing of this fundamental measurement. Time, considered the back drop upon which events across the universe unfold was an idea held to very basic to the makeup of quantifying nature and thus reality in turn. However following the phenomena of Special Relativity by Einstein in 1905, the pre supposed uniform ticking of time was shattered.
Special Relativity follows that time is not uniform for all observers but relies crucially on your frame of reference, everything is relative. So here comes our first counterintuitive bombshell upon which we shall expand. Observers in relative motion have different perceptions of distance and of time. For example, identical clocks traveling in relative motion will tick at different rates and therefore this means that they will not agree on the amount of time that has elapsed between markers. This is no clockwork fault but rather a peculiar property of time itself. This revelation is counterintuitive and puts a spin on our idea of a steady reality due to the fact that these seeming incongruities only occur when travelling at a substantial fraction of the speed of light, an activity fairly rare to ones daily life.
Special relativity relies on two elements, the principle of relativity and the absolute constancy of the speed of light. For all objects in force free, constant velocity motion the principle of relativity allows it to be understood that each object at set velocity has a perfectly justified claim that they are stationary. Taking the example of subject A on a train and subject B standing on the platform, as long as A’s train is travelling at constant speed, with the blinds pulled down the subject will be utterly justified in claiming they are at rest (as they feel no force suggesting otherwise or have no comparison available) however subject B sees the train passing by and therefore claims that they are the true observer at rest. This captures relativity as without comparison with “outside objects” can physical meaning of velocity come about, there is no “absolute” constant- velocity motion, everything is to do with a frame of reference.
The constancy of the speed of light coupled with the principle of relativity led Einstein to his final revelation concerning special relativity. Life exists in the three spatial dimensions and a fourth equally important time dimension, together spacetime. Motion too, is shared between these different dimensions, this is the great leap. As well as physically moving through space, movement through time is ever constant. When at rest, an objects motion is entirely though time, (at the speed of light). If, hypothetically an individual managed to travel at a significant fraction of the speed of light, their motion in a spatial dimension would be so great that, crudely put, their motion in the time dimension would have to compensate for this as it is diverted. Time, for such a high speed moving individual, would slack; this is known as time dilation. It is important to remember, that time is not slowing down, it is passing at a slower rate relative to a stationary observer.
Essentially for photons travelling at the speed of light all their motion is through space, so time is non-existent. If travelling at a significant fraction of the speed of light, (which has been experimentally confirmed with muons at CERN and their decay rate) time would pass slower and the life expectancy of a traveler would indeed be much longer, for this traveler 6 years could pass although for a stationary observer 600 may. The secret to eternal youth found? No, the catch is that although time would pass slower for them, so would everything else, all the workings of life itself. To the traveler it would seem as though 6 normal years had passed, whereas to the observer it would seem that the traveler was living these years of their life in hyper-slow motion. The life expectancy would be longer as witnessed by the observer, but amount of life that could be enjoyed by the subject is no more.
So we can see a commonly held misconception regarding the rigidity of space and time unfolding. Our outlook on reality depends on the relative viewpoint between the individual and the observer; reality from different perspectives is equally justified but not equally perceived.
At the smallest, subatomic level, quantum mechanics has made astonishing discoveries about the behavior of elementary particles. Seeing as these particles are the primary building blocks of the entire universe surrounding us, it would seem logical to assume that by studying this we might gain valuable insight into the true nature of reality. However peering down the rabbit hole into the quantum world reveals some hard to swallow truths.
Quantum mechanics, the realm where common sense and intuition must be abandoned and the nature of the results accepted for what they are, often truly bizarre. The Quantum revolution required we shed our classic perspective because new results established that they were demonstrably wrong. Just as special relativity requires changes in viewpoint when things are moving very quickly, quantum mechanics requires a modification in the field of the minutely small. So, another basic conception of our understanding concerning how things work, in our presumed reality, is becoming obfuscated.
The experiment which sums up the unfamiliar behavior of the quantum world is The Double Slit experiment. In this experiment, a beam of light is shone on a barrier in which two slits have been cut. The light that passes through the barrier is then recorded on a photographic plate, when either or both of the slits are open. Even when firing single photons, if both slits are open a wave interference pattern occurs, commonly only produced by interfering particles on a wave front. When detectors are put by the slits however, strangely the interference pattern disappears and it’s as if the photons are again attacking as we would expect in the normal world, going through either one slit or the other, because paradoxically how can something be in two places at once. It’s although our observation has altered the behavior of the electrons, a disturbing idea we shall return to later.
It’s as if the photons are acting in wavelike manner to build up the interference pattern on screen. So the idea of “wave-particle duality” has come into being, quantum mechanics brings up to the idea that something can be either a wave or a particle. According to de Broglie in 1923, it was suggested that this duality can be applied to not only photons but all matter, by setting down a formula for the wavelength of matter waves which shows the wavelength is directly proportional to the momentum of the matter, with the incorporation of Planck’s constant, ħ. This fundamental constant is the basis for the alien quantum behavior. Just as the extremely large value of the speed of light obscures much of the true reality of space and time, the extremely small value of ħ (6.63 x 10-34) obscures the wave-like aspects and other odd workings of matter in our day-to-day world.
Another confusing aspect of the quantum world is the fact that probability is the replacement for precision. Microscopic objects must be described in a probabilistic manner; the best we can say is that an electron has a particular probability of being found at any given location. In the macroscopic land our equations can be applied to pinpoint the location of objects in the familiar dimensions of space and time, yet the conventional outcome break down in the micro world. Electrons have such things called probability waves, indicating where an electron is most likely to be found, unlikely to be found and probabilities in between. The question we must ask however is, is it amazing enough that even in the Newtonian world the mathematics we apply actually yields outcomes which fit observations exactly? As we then have drawn inferences from this that maths can fit the natural world. Then with the quantum world, can we still apply this same principle, take the liberty even, that inferences from that math can be directly applied to what is occurring in the physical world? If this is what we choose to do, what does it really mean to have a probability wave? Does it mean that a particle “chooses” one of these many possible futures to follow, or could it instead split off to live out all possible futures in an ever branching arena of parallel universes?
A particularly creative interpretation of quantum theory is known as the Many Worlds Interpretation, originally produced by Hugh Everett a student of the famous physicist John Wheeler. It applies the mathematics in quantum mechanics, Schrodinger’s equation, to suggest that instead of one distinct outcome happening, all possible outcomes happen, each occurring in its own separate universe. Everett’s postulate implies that all isolated systems evolve according to the Schrodinger equation concerning wave functions. The probability predicting a particle may be here or there actually reflects that in one universe it is here and in another universe it is there. Say, as an illustration if a coin is flipped, the probability of it landing heads or tails is 50:50, however instead of one outcome occurring, both occur, both heads and tails but in different parallel universes. As the coin is flipped, crudely speaking, the universe “splits” in two, in each with a future occurring either heads or tails, and you in each universe looking at the outcome thinking, that your reality is the only reality. Many-worlds claims to reconcile how we can perceive non-deterministic events, such as the random decay of a radioactive atom, with the deterministic equations of quantum physics. Prior to many-worlds, reality had been viewed as a single unfolding history yet through the MWI reality can be seen as a many-branched tree, wherein every possible quantum outcome is realised.
This Many Worlds Interpretation is only one of many parallel universe theories. The idea of parallel universes may seem to be one which should remain in the realm of science fiction and comic books, yet it interprets the mathematics to attempt to understand physical reality in possibly the most conservative and precise manner to come to the conclusion of a multiverse scenario. The idea of endless doppelgangers remains slightly farfetched, although this is an interesting feature of the multiverse theory. In the vast unknown there may in fact be infinitely many “yous” some far richer, some poorer, some reading this simultaneously as you are and others who unlike yourself in this reality have got bored long ago and have discarded this paper in the hope of finding something much more less peculiar to read.
Another popular interpretation of the quantum mechanics, which does away with every branching universes, is the Copenhagen approach. This envisions that whenever measured or observed, a particle’s probability wave instantaneously collapses, known as wave function collapse, to one location. The range of possible positions for the particle transforms into one definite outcome. According to the theory, it is in fact our observation which causes the particle’s probability to converge to one particle point, and exhibit familiar behavior, however look away and the probability wave rapidly spreads again indicating a variety of points the particle would be likely to be found. This idea is supported by the evidence we observed in the double-slit experiment as when detectors were placed near the slits the photons displaced the behavior of being observed passing through either the left slit or the right. So according to Copenhagenists every time you observe, the probabilistic vagueness disappears and is replaced by our familiar reality. A well known illustration of this interpretation is the thought experiment of Schrodinger’s cat. The experiment presents a cat that may be alive or dead, and paradoxically implies that before observation the cat can be seen as simultaneously alive and dead, yet it is when we actively look in the box that one future ensues, reality is observer-dependent.
“Observations not only disturb what has to be measured, they produce it….We compel [the electron] to assume a definite position…. We ourselves produce the results of measurements.” Pascual Jordan.
Is it then that if observation is caused by consciousness, that consciousness itself is the ground of being? And if so, upon analysing this “mechanism” of collapse how do we define what level of consciousness will suffice? This idea sparked one of the most controversial debates regarding the philosophy of science; between the two key figures and founders of quantum mechanics, Niels Bohr and Einstein. Refuting whether reality could be as counterintuitive as the quantum world suggested with the influence of the Copenhagen interpretation or based upon a deterministic model, rather as Einstein put it “realistic” as “God does not play dice.”
And so we return to the philosophical question of whether the world really exists, independent of our perception, or whether it alone creates it. Einstein being one who found this idea very troubling indeed, he counterclaims that,
“That which really exists in B should …not depend on what kind of measurement is carried out in part of space A; it should also be independent of whether or not any measurement at all is carried out inspace A.
If one adheres to this program, one can hardly consider the quantum-theoretical description as a complete representation of the physically real.
If one tries to do so in spite of this, one has to assume that the physically real in B suffers a sudden change as a result of a measurement in A.
My instinct for physics bristles at this.”
Einstein’s most powerful attack on the quantum theory view of reality independent from observation comes in the form of his EPR paper. The EPR paper describes a situation ingeniously contrived to force the quantum theory into asserting that properties in a space-time region B are the result of an act of measurement in another space-time region A, so far from B that there is no possibility of the measurement in A exerting an influence on region B by any known dynamical mechanism. Under these conditions, Einstein maintained that the properties in A must have existed all along.
The EPR argument is a key example of the opposing ways each quantum founder viewed nature. Einstein argued the system being measured is a physical reality, which can be disturbed by an observer or second system. Bohr, however disagreed maintaining that concepts such as position and momentum were completely meaningless, unless they were incorporated as pieces of a complete system, in relation to an observer. In summary then, it was Einstein who possessed both a supposedly ‘realistic’ and deterministic attitude regarding nature, whereas for Bohr, reality was not only being based upon observation, it did not exist independent of it.
Returning briefly to the Double-Slit experiment, which Feynman described as being the pivotal mystery to quantum mechanics, applying our explored theories, we can see that the Copenhagen interpretation does fit the phenomena that when unobserved a interference pattern occurs, which would reflect the probability wave of an photon unobserved. Yet when detectors are placed, the wave function would appear to “collapse” and photons can be directly observed acting as “bullets” in precise locations. Yet the conventional deterministic viewpoint, leaves us with a troubling outcome as to where we cannot predict the exact outcome without observation, and instead encounter our baffling interference pattern.
As for the theories of parallel universes proposed to explain the phenomena seen in the experiment, these theories are simply interpretations that do not make predictions, and cannot be falsified. In the more naive theory, an electron confronted with the two slits causes the universe to split in two — with the electron going through one slit in one universe and the other slit in the other universe yet this “explanation” fails to explain the appearance of interference. A more “adjusted” parallel universes theory holds that an infinite number of parallel universes exist at all times and that “shadow” electrons (or photons) from the parallel universes cause interference with the particles in our universe, causing the observed pattern, handy indeed.
Another jump from common reality comes from the physicist Werner Heisenberg in1927 and the uncertainty principle. As previously mentioned we cannot distinctly say where a particle is at a certain time, only the probability of its whereabouts can be measured. When trying to observe the position of a particle we can use a wavelength of either high frequency, which reduces the margin of error equal to the wave’s wavelength hence locating a particle with greater precision in position. Yet, with such a high energy frequency, the electrons velocity is disturbed. Or a low frequency wave can be used where we minimize impact on the electrons motion but offset our precision in its position due to a larger margin of error in the wavelength. So lies the quantum mechanical balancing act. Now, for how this uncertainty principle affects our conventional reality; it gives rise to an astonishing effect known as quantum tunneling. Just as there is a tradeoff between the precision of measurements of position and velocity, Heisenberg shows there is a similar tradeoff in the precision of the energy measurement of particles and how long the observer takes to do the measurement. This is because the energy of a particle can violently fluctuate over short time scales and ever increasing precision of energy measurements require longer durations to carry out. Essentially, a fluctuation could occur where a particle “borrowed” energy as long as it was “paid back” in a short enough time span. Therefore quantum mechanics dictates that the jist of this tradeoff is if one attempted to walk into a solid wall for long enough, eventually (albeit the time taken for the number attempts would probably be longer than the age of universe) you would emerge on the side. All your individual particles would have to be fortunate enough to “borrow enough energy” to tunnel together yet the probability is, with enough time it would be accomplishable. This principle alone is baffling to our intuition, with the possibility of disappearing through Platform 9 ¾, hope still glimmers.
Without diverting too much from possible hidden features of reality, a short summary of possibly the most exciting up and coming scientific theory, a contender for the big TOE (theory of everything), string theory is essential to another coming revelation.
As seen, the view prior to string theory was the standard model of particle physics, governed by the equations of quantum mechanics. String theory does away with this idea and proposes instead that everything is fundamentally made of tiny, vibrating, elementary strings. What gives rise to the seemingly different elementary particles is, different vibration patterns; mass, charge, force, are all properties which result from unique vibrating string patterns. It is easy to see why this theory has attracted so much attention; its ability to explain the previous random properties of particles in such an elegant and uniform manner seems to be the long lost key. Amazingly, unlike other theories, gravity arises as a natural produce from within the theory, a pattern of string vibration ultimately matches with the properties of the graviton, meaning gravity is intrinsically part of this quantum theory, instead of an in-put, a novelty indeed. Without going into detail, which would require much more than a paper alone, the overall beauty of string theory is that it is managing to unify the conflicting principles of general relativity and quantum mechanics. These two fundamental pillars of physics, previously incompatible left our knowledge of physics torn into two separate fields, one for the very large and one for the very small. This represented a flaw in our understanding of the physical universe, but as a result of string theory it seems we may be on the path with a theory which can harmoniously unite it at an elementary level.
Now an intriguing feature of string theory is that it involves the prediction of extra hidden dimensions, it actually requires the existence of several extra, unobservable dimensions to the universe! In our everyday experience, we set our perception within three dimensional spatial framework, when moving our motion can take place in three dimensions, left/right, backwards/forwards, up/down. This feature of our universe is so basic to our reality that this truly would be another mind-boggling step down our path of counterintuitive revelations to question otherwise. However, this suggestion is in fact concrete and completely plausible. String theory suggests that the spatial fabric of our universe may have both extended and curled-up extra dimensions, in such a small space that they cannot be directly observable. This possibility of these extra space dimensions is called Kaluza-Klein theory and the shapes they could theoretically occupy are dubbed Calabi-Yau space.
It was as Einstein had so successfully achieved in his ground breaking theory of general relativity, showing the fabric of space and time could curve and warp itself, effectively acting as the communicator of gravity, that led Kaluza to propose that there were perhaps extra dimensions aside from the main three that too were curved, except this time curved on such a miniscule scale that they were undetectable to even our finest probes.
A standard analogy for this is to consider multidimensional space as a garden hose. If the hose is viewed from a sufficient distance, it appears to have only one dimension, its length, but at closer inspection we realise it has a second dimension its circumference and then a third its width. Similarly the extra dimensions are only “visible” at extremely small distances. Now by small this means, smaller than a billionth of a billionth of a meter, less than the Planck length to make them completely undetectable by the most advanced scientific equipment. It’s because according to string theory as a string oscillates, the geometrical form of the extra dimensions is vital in determining resonant patterns of vibration. The string vibrations appear as the fundamental elementary particles with fundamental properties by the geometrical size and shape of the extra dimensions. Are rigid boundaries of space-time are cracking…
The 20th century gave us the “quantum leap” era of Physics with revolutionary ideas from Einstein to Neils Bohr to Schrödinger, through to the forefront of string theory physicists today. With these paradigm-shaking discoveries, physics has sought to question and explain everything from elementary constituents to the fabric of the universe. The quantum and relativity theories explored have blown past the clockwork, provincial Newtonian perspective, revealing workings beneath the confines of ordinary experience. Although our scientific tools and minds are ever growing is there to be a limit to our comprehensibility. It seems with science and mathematics we have built up a repertoire from which we can apply knowledge and exploit it to humanities advancement. However in sight of an age of rapid and impressive progress the astonishment at the ability to understand the universe can be lost. As Einstein once troubled, “The most incomprehensible thing about the universe is that it is comprehensible.” The fact that our scientific methods can yield results alone is perplexing and can we ever fully understand why this is so. Maybe it must be accepted that the universe is in existence due to some higher reasoning, divine choice or…fluke. The time may come when advancement is not hindered by scientific technology but human understanding itself.”
Our pursuit of knowledge and understanding propelled by conscious thought is paramount. We continue to examine our surroundings rigorously, those who experiment dubbed scientists, proposing theories of relation between ourselves, each other and the world, those who muse dubbed philosophers, be the interactions idealist or realist, the ground for understanding empiricist or rationalist. As humans it is an intrinsic part of our nature to partake in these activities, and through the merging of these forms of thought we hope to grasp the true nature of reality. However perhaps explanation is not always possible, perhaps a hidden understanding was not built into the system, waiting to be unveiled. The success of the scientific method in the past has encouraged us to think that with enough time we can unravel nature’s mysteries but the enigmatic universe is rich and exciting, and despite the bigger questions perhaps we should just enjoy what has been presented.
“Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.” Albert Einstein