A Brief History of the Theory of Everything

Stephen Hawking Makes a Joke, and it Works

Süddeutsche Zeitung, September 2010

Stephen Hawking has disproven the existence of God in his new book, The Grand Design, written with co-author Leonard Mlodinow, who teaches probability in Pasadena and writes TV screenplays on the side. The two authors make use of string theory, long known as the “theory of everything,” and now better known as “M-theory.” According to the authors, this theory may soon provide us with a theory of everything that has no place for a creator. Clearly, this is not a trivial question.

Only a few scientists have ever had a brilliance that transcends the bounds of their own disciplines. Humphry Davy was the first example among modern scientists, a colorful figure in early 19th-century London. A century later, Albert Einstein practically became an overnight pop sensation when his spectacular theory of relativity was confirmed by the observation of the precession of the perihelion of Mercury. But even before that, he was fully convinced of his own theory. Why? He couldn’t imagine it any other way. It’s a mistake to be misled by Einstein’s sometimes childish demeanor, just as it’s a mistake to believe that he was joking when he said that God doesn’t play dice. Einstein was clearly a deadly serious man.

With Stephen Hawking, it’s just the opposite. Hawking is a phenomenon. Other physicists, like Richard Feynman and Harald Fritzsch, have written extremely successful books in the postwar era. The former received the Nobel Prize for his quantum theory, while the latter can claim the discovery of the quark, which the Nobel strangely ignored. Stephen Hawking, for his part, can boast of having held the Lucasian Chair of Mathematics at Cambridge University. The list of his predecessors in that office inspires respect, not only on account of Isaac Newton. But respect alone can’t explain the fact that Hawking’s A Brief History of Time is one of the bestselling books ever. Aside from the topics of his writing and the quality of his prose, Hawking benefited from the fact that he does not conform to the typical image of a genius, as Nietzsche once portrayed it. Hawking is not a daunting figure who towers over his time and his readers. In fact, he’s a surprisingly approachable figure, and his wheelchair and speech synthesizer don’t stop him from cultivating a well-developed public image. He’s a pleasure to listen to. By the way: Some neurologists believe that “genius” generally has its origins in brain disorders, which lead to abnormal thought patterns. But who wants to be a genius, anyway? Hawking would rather be liked.

The search for a theory of everything, began in Copenhagen in 1820. That’s when the Danish scientist Hans Christian Oersted, experimenting with a battery twenty years after its invention by Alessandro Volta, happened to notice that a compass needle responded whenever an electrical current was turned on nearby: It aligned itself perpendicular to the electrical cable. Oersted wasn’t the first to notice this effect, but he immediately grasped its implications. He wrote a report that spread quickly throughout Europe, though it was written in Latin and often had to be translated into other languages before it was read. What made his discovery surprising was the fact that two natural phenomena – magnetism and electricity – appeared to be linked to each other. The leading opinion at the time would have held that to be impossible. Among the doubters was the great Charles Augustin de Coulomb, who later lent his name to the unit of electrical charge. Coulomb had always been convinced that magnetism and electricity were two fluids that could not flow through each other.

Oersted’s observation was initially taken to indicate not a new harmony, but rather a “conflict between electricity and magnetism,” until it triggered a major change in paradigms in the realm of natural forces. Instead of separating natural phenomena into isolated processes of one kind or another, famous scientists such as André-Marie Ampère, Alexander von Humboldt, and Humphry Davy began frantically seeking a law that explained this whole interaction as a single process. Now the search was on for a theory that would explain everything. Success came to Michael Faraday, a completely unknown lab assistant who solved the riddle during summer vacation in the basement of the Royal Institution in London, laying the groundwork for the theory that later came to prominence as magnetic field theory. The theory was worked out in detail by William Thomson, aka Lord Kelvin, and above all by a strange character from Scotland by the name of James Clerk Maxwell. The theory was based on Faraday’s assumption that the lines made by iron filings were lines of magnetic force, which required time to spread out in space. The behavior of the lines in response to changes in the electric charge was called electrodynamics, and its sensational byproduct was the understanding of light as waves in these fields of lines. This theory replaced Isaac Newton’s conviction, sacrosanct until then, that light is a particle.

The mathematical complexity and beauty of electrodynamics were unprecedented. Around 1890, this first theory of everything was hailed as the “end of physics.” Professor Philip von Jolly in Munich even advised Heinrich Hertz, Max Planck, and Albert Einstein not to study physics, explaining that there was nothing left to discover.

But hardly had these words been spoken when doubts arose. The lack of any evidence for the hypothesized aether through which waves were thought to travel; the photoelectric effect observed by Heinrich Hertz, which could not be explained as a product of waves; and the consistency of the speed of light, regardless of the movement of the observer relative to its source, led within just a few years to theories of relativistic quantum fields, characterized by a peaceful coexistence of waves and particles. The so-called “standard model” that is accepted today was one of these theories. It describes electromagnetic and atomic forces, and has been confirmed by precise experiments. But we are still searching for the theory of everything, which has to do with the stage on which the theater of our world is played out: Space-time.

Space-time, too, had slowly but surely undergone a paradigm shift, from a construct based on sharply distinguished elements to a dynamic unity. In the mid-18th century, Gotthold Ephriam Lessing had insisted in his famous work “Laocoon: An Essay on the Limits of Painting and Poetry,” that the painter’s task is to portray simultaneous events in space, and the poet’s to represent the movement of bodies in time. Anything else would appear tasteless.

This opinion did not prevent Charles Babbage, who pioneered computation theory together with Lord Byron’s daughter Ada Lovelace, from writing in 1837 that sound impacts atoms, stores its energy in them, and thus creates an archive of everything that has ever been said – lies included. As soon as they have been dispersed in the air, the words that were originally uttered one after the other are no longer distinguished by anything but their position. In water, for example, sound could be instantly frozen. But even without this ideal case, the theory brings God into play. The Almighty can naturally use this archive at any time, however complicated it may be to read. He can track down every murderer, not to mention every unbeliever. Almost unnoticed, time has here become space, and space has become a means of storing and overcoming time. Ultimately, there is no difference in theory between hearing a sound over the course of time, and running along in space to hear the traces that the sound has left in matter. This simple consideration is at the root of one of the greatest revolutions in human thought.

The next step was taken by the Prussian jurist Felix Eberty, who applied Babbage’s ideas to light. Indeed, dear reader, the man in the moon has just seen that you scratched your forehead a second ago, because that’s how long it takes for light to get to him. And your friend in some far-off galaxy has just seen what you did last year, or sometime last decade. Even worse: Every bit of this information is stored in the traveling waves. According to Eberty, God’s eye follows along on this archive of light and examines every second of the past. Eberty published his work “The Stars and the Earth” anonymously in 1846, perhaps out of fear of the church. His brief work shared the exceptional elegance and rapid acclaim of Hawking’s new book. Karl Clausberg recently published a new edition of Eberty’s work with extensive commentary. Not for nothing: In 1923, an edition was published with a foreword by Albert Einstein, who praised Eberty’s critical spirit and noted the work’s correspondence to the theory of relativity.

Einstein probably already had the book in his hands in the 1880s, when his family outfitted the Oktoberfest and Schwabing with electric street lights. The small city near Munich was the first in the world to have streetlights that blocked out the night sky, which had once inspired respect and the fear of God in people. With that, a rupture took place that would be brought to its conclusion by Hawking and Mlodinow.

Einstein was nine years old at the time. For the rest of his life, he would wonder what it was like to ride on a wave of light. Later, he arrived at a simple answer to the question of how to reconcile space and time with the curious consistency of the speed of light: You just have to bend them to fit. But Einstein still thought of the universe as static. Not until Edwin Hubble’s observations of cosmic background radiation did we arrive at the contemporary model of the expanding universe, which must once have been very small and hot. But the Big Bang, and the infinite density it entails, lie beyond the purview of our current theories. This is unsatisfying. And that’s not all: Looking at the more and more complex, more and more beautiful equations that have been derived to explain particle reactions long after the Big Bang, it’s easy to feel like you’re standing at the bowling alley in your underwear, with raw eggs in your hand. Quantum field theories aren’t consistent with space-time, in fact many tricks are required to make the calculations of quantum theory even approximately accurate for massive particles. Ever since Einstein, mass has been seen as the “charge” of gravitation. What we’re missing is quantum gravity.

That’s where the new M-theory comes in. M stands for mother, or mystery, or whatever you please – that’s how cool they are at Cambridge! To our satisfaction, we learn that in M-theory elementary particles – which have a restmass but no volume, and thus have infinite energy density just like the universe at the time of the Big Bang – have been replaced not only with strings, but also with membranes and even higher-dimensional objects. The concept of strings was so aesthetically insufficient that it never convinced the majority of physicists, even though it managed to pull a graviton – the hypothetical quantum particle of gravitation – out of its hat. But now the simplicity that used to make strings so sexy to their fans is gone, too.

Also, whereas strings required ten dimensions of space-time to provide consistency for this theory, now it’s eleven. That’s not a problem for a physicist. After all, we still only have three when we’re watching TV: The height and width of the screen, and the dimension of time, which we quickly forget once we start watching. Still, it would be nice to have some reason to believe that these eleven dimensions actually exist. The fact that now all five formerly competing string theories are included in M-theory speaks neither for nor against it. It’s hard to know when M-theory will be understood clearly enough to be simplified, so that all the phenomena of nature can be calculated using just one experimentally measured parameter. Compared to Newton’s discovery of gravity and Einstein’s equivalence principle, even compared to Faraday’s new insight into the operation of forces in space-time, M-theory appears at the moment to be mere technophilia.

Hawking’s books manifest the same strength as his scientific work: Once he starts down a path, he follows it all the way to the end. Naturally, this is also his weakness. Anyone seeking information about the current state of physics from the new book will be disappointed. Alternative ideas about the quantization of space-time don’t even merit a mention – for instance, the quantum groups which use Heisenberg-type uncertainty relations not only between position and momentum, but also between two positions or two momentums, thus violating symmetry in the most elegant fashion. The symmetry that Martin Bojowald has found, which postulates an inside-out universe before the Big Bang, appears unknown to Hawking and Mlodinow. Maybe these are individual cases. A more troubling omission could be their failure to ask what the quantization of gravity actually is, and whether it even necessarily exists. Perhaps after all the decades and the widely divergent ideas of relativity and quantum fields, a totally different word than “quantization” would be preferable to Hawking’s borrowing of Feynman’s term for subatomic forces. In the end, space-time relates to quanta as intelligence does to genetics: We don’t understand the system at all, and both terms are in urgent need of an overhaul. Perhaps for all our agility, we still fail to pose the right questions.

Of course, finding fault with a book like The Grand Design on these grounds is a bit like drinking monk’s beer out of a wine glass after holding it up to the light like a connoisseur. This sort of reflection is not part of the authors’ plan. They also aren’t concerned about whether there could only be a finite number of different natural laws deep inside the particles, between the Big Bang itself and the moment thereafter. Given that temperature increases exponentially the closer we get to the Big Bang, such a conclusion is actually improbable. Hawking doesn’t question the concept of the theory of everything, which has remained popular since Oersted’s discovery. Nevertheless, we owe him and Leonard Mlodinow our thanks for this book. They can hardly be blamed for the fact that M-theory isn’t immediately comprehensible, the way that Eberty’s idea of preserved images may be. Rather, they should be praised for all that The Grand Design offers the reader. This is due to the remarkable elegance with which individual questions are brought to light. Even a passionate reader rarely encounters such a literary jewel.

Whereas Hawking’s Brief History of Time kept its eloquence in bounds, here he exhibits sheer brilliance. With instinctive certainty, Hawking and Mlodinow sketch out the major questions in the first few sentences: Existence, limitations, searching, reality, creation in this “world that is by turns kind and cruel.” It’s about the big questions, or let’s say: It’s about everything, to the millionth power. The authors at once declare philosophy dead, in order to let physics take over. These tones are usually only struck in conversion texts, whose linguistic economy is fed by their lack of doubt. The impression is sublime. Hawking and Mlodinow carry out their program with love and knowledge, and without mercy. Driven towards salvation by their own brilliance, they quickly establish that quantized uni- and multiverses fluctuate into being from nothing, just as the elementary particles do. Time as we know it doesn’t exist there. Everything, nothing, and us: A dream that needs no God, because it comes from nothing. Rather, the anthropic principle applies: Everything is the way it is because we fragile beings are here. The slights done to mankind by Copernicus, Darwin and Freud are all forgotten. It’s an extremely mischievous trick, played for the reader’s benefit, and it won’t bother God, who’s suddenly superfluous, anyhow.

Hawking and Mlodinow know this, too. They’ve studied their predecessors well, and they tell just the right anecdotes, such as one about Johan Kepler’s idea that planets have senses with which they observe the laws of nature. Their wit, like their figurative language, functions without a hitch. Of course, they also know what the Sandemanian Michael Faraday knew: That religion cannot be subjected to criticism. For the mystery of being has a hold on people, as Hawking demonstrates so powerfully in his first paragraph, and it leads them to answers. So he writes about those, too – and convincingly. Rarely has anyone written more beautifully, sharply, and inspiringly about the universe and the ultimate questions of our existence. The last chapter alone, which deals with free will and natural law, is a gem that belongs on every bookshelf. Ideally next to other sacred texts.

Copyright by Ralf Bönt

English by Kurt Beals