HBO has recently been broadcasting the 2014 movie The Theory of Everything; the biographical film about the relationship between Stephen Hawking and his wife Jane Wilde.
The movie is adapted from Jane’s memoir Traveling to Infinity: My Life with Stephen and, consequently, it is supposed to accurately depict key moments of their life together (1). But, how accurate is the movie in depicting Hawking’s science? Since I am not a physicist, my answer is based largely on Hawking’s book, A Brief History of Time (2).
But first, consider that the movie is meant to entertain a general audience, which is not likely to want to sit through the intricacies of general relativity and quantum mechanics. Hawking himself tells us that when he was writing A Brief History of Time, he accepted the advice that every formula he published would halve his sales.
We begin with a scene from the movie, in which Hawking is shown having a sudden “aha” moment that leads to his major scientific achievement—his discovery that black holes emit particles and radiation. [The myth of Isaac Newton and the apocryphal apple is perhaps the most famous example of this cliché.] Hawking is seen looking at burning coals in his fireplace, through a sweater that he is struggling to pull over his head. Jane comes in, and Stephen announces, “I have an idea.”
Did Hawking indeed have the “aha” moment depicted in the movie? Hawking does not talk about it in A Brief History of Time. Nor do I recall mention of such a moment from any other source.
Hawking explains the thinking that led to his breakthrough in A Brief History of Time. He begins by making the case for entropy within black holes. Next, “If a black hole has entropy, then it ought to have a temperature. But a body with a particular temperature ought to emit radiation at a certain rate. It is a matter of common experience that if one heats up a poker in a fire it glows red hot and emits radiation.”
Did Hawking’s reference to a “poker in a fire” in A Brief History of Time inspire the movie’s producers to portray his key breakthrough as coming from staring at the coals glowing in his fireplace? Regardless, representing Hawking’s discovery in this way is a disservice to the science because it disregards the intense effort that lay behind it. Hawking worked strenuously, over a period of months, to prove his case; which he did with mathematical rigor. Moreover, since he remained troubled by the prevailing view that “by their very definition, black holes are objects that are not supposed to emit anything (2),” he spent more months trying to figure out where he might have gone wrong. But, he hadn’t gone wrong. In brief, the explanation stems from the uncertainty principle of quantum mechanics, which predicts that certain pairs of quantities, such as the position and velocity of a particle, cannot both be known with complete accuracy. [The uncertainty principle, formulated by Werner Heisenberg, is a cornerstone of quantum mechanics. For more on Heisenberg, see reference 3, in particular Asides 6 and 7.] See Aside 1.
[Aside 1: Hawking’s “aha” moment in The Theory of Everything reminds me of a similar moment portrayed in the earlier (2001) movie A Beautiful Mind, about mathematician John Forbes Nash Jr. In that movie, Nash’s “aha” moment—which led to his Nobel Prize winning work in economics—happened when a nasty rejection from a blond in a bar led Nash to suddenly realize that pursuing one of the more numerous brunettes was much more likely to lead to a successful outcome.]
The movie depiction of Hawking’s signature discovery also feeds the cliché that great scientific breakthroughs are the products of eccentric geniuses working in isolation. Actually, Hawking’s breakthrough was inspired by his 1973 meeting in Moscow with two leading Soviet black hole experts; Yakov Zeldovich and Alexander Starobinsky, who convinced Hawking that “according to the quantum mechanical uncertainty principle, rotating black holes should create and emit particles (2).”
Hawking also admits to being motivated by physicist Jacob Bekenstein; at the time a graduate student at Princeton. Bekenstein suggested that the area of a black hole’s event horizon (i.e., the black hole’s boundary) is a measure of the black hole’s entropy. And, as noted above, if a black hole has entropy, it has temperature, and thus must emit radiation (2).
The Theory of Everything shows Hawking introducing his discovery, in public, for the first time, in front of a small audience, in a small lecture hall, while seated in his wheelchair. The blackboard behind him is blank. When he finishes speaking, someone in the audience jumps up and declares that the theory is “complete nonsense,” and then storms out. Hawking impishly says to the departing individual, “Was it something I said, Professor?” Next, a Russian physicist stands up and announces that “the little one has done it (i.e. succeeded).” With that endorsement, Hawking becomes world famous, and his face adorns the cover of Nature.
Although aspects of the depiction of Hawking’s lecture seemed unrealistic to me, the incident actually did occur, and it was not entirely unlike its portrayal in the movie. It was during a conference at the Rutherford-Appleton Laboratory near Oxford. Hawking relates, “At the end of my talk the chairman of the session, John G. Taylor from Kings College London, claimed it was all nonsense (2).” The Russian physicist who commended the discovery was Isaac Kalatnikov, who earlier showed that the universe could have had a singularity (see below).
The movie intermixes the lecture scene with another scene, in which one of Hawking’s friends is explaining to others how a black hole can eventually go poof. The purpose of the intermixed scene may have been to provide a context for Hawking’s discovery. In any case, Hawking himself comments on the implications of the discovery as follows: “The existence of radiation from black holes seems to imply that gravitational collapse is not as final and irreversible as we once thought (2).” He goes on to explain that Einstein’s theory of general relativity, taken alone, predicts that any matter falling into a black hole would be destroyed at the singularity (a region of zero volume in which the density of matter and the curvature of space-time become infinite), while the gravitational effect of the black hole’s mass would continue to be felt on the outside. But, “when quantum effects were taken into account, it seemed that the mass or energy of the matter would eventually be returned to the rest of the universe, and that the black hole, along with any singularity inside it, would evaporate away and finally disappear.”
Another of Hawking’s discoveries—that the universe may have come into existence from a singularity—is also highlighted in the movie. That discovery happened before his finding that black holes emit radiation. In fact, it was the subject of his doctoral thesis. The seed for the discovery was planted by physicist Roger Penrose’s proposal that a star collapsing under its own gravity eventually shrinks to a singularity. The movie indeed acknowledged Penrose’s contribution. What’s more, Penrose is also shown serving on Hawking’s dissertation committee.
Importantly, Penrose’s theorem applied only to collapsing stars. Hawking’s innovation was to ask whether the entire universe was a singularity in the past. “I soon realized that if one reversed the direction of time in Penrose’s theorem, so that the collapse became an expansion (2),” the conclusion would be that an expanding universe must have begun as a singularity. An important corollary is that the universe had a beginning. [Time and space too were created in the transition from nothing to something. There was no time before the big bang and, consequently, the big bang didn’t actually take place in time. Another interesting notion: since time came into existence at the moment of the big bang, there was never a moment in time when the universe did not exist.]
Penrose’s theorem about stars collapsing into black holes influenced Hawking in yet other ways. Hawking explains: “… at the time that Penrose produced his theorem, I was a research student desperately looking for a problem with which to complete my Ph.D. thesis. Two years before I had been diagnosed as suffering from ALS, commonly known as Lou Gehrig’s disease, or motor neuron disease, and given to understand that I had only one or two more years to live. In these circumstances there had not seemed much point in working on my Ph.D.—I did not expect to survive that long. Yet two years had gone by and I was not that much worse. In fact, things were going quite well for me and I had gotten engaged to a very nice girl, Jane Wilde. But in order to get married, I needed a job, and in order to get a job, I needed a Ph.D…The final result was a joint paper by Penrose and myself in 1970, which at last proved that there must have been a big bang singularity provided only that general relativity is correct and the universe contains as much matter as we observe (2).” And, as we know, Hawking and Jane were married. See Aside 2.
[Aside 2: Almost coincident with The Theory of Everything, there was another movie biography about a British scientist—The Imitation Game, about British mathematician and computer pioneer, Alan Turing, and his work in breaking Germany’s Enigma code during World War II. Despite its excellence, The Imitation Game leaves the impression that Turing virtually single-handedly, and with no prior basis to proceed from, invented and built the machine (the bombe) that broke the German code. Yet a machine, similar to Turing’s, which used rotors to test different letter combinations, was invented earlier by Polish cryptographers. Turing’s very significant contribution was to modify the Polish machine to recognize and ignore letter combinations that were unlikely to yield a useful result, thereby greatly speeding up the screening process. Moreover, the movie does not even mention mathematician Gordon Welchman—he and Turing were among the four original recruits to Britain’s code breaking center at Bletchley Park,—who substantially improved Turing’s machine. Welchman’s improved version of the machine actually broke Enigma ciphers during the war. Incidentally, after the war, Welchman taught the first computer course at MIT. Turing is generally considered to be the father of computer science, and I certainly do not mean to disparage him. My point is that even very good movie biographies of scientists take license with the science to enhance the drama.]
The Theory of Everything may have left some viewers with the impression that the notion of an expanding universe originated with Hawking. Actually, in 1929 Edwin Hubble discovered that the universe is expanding in all directions. And, importantly: “The discovery (Hubble’s) finally brought the question of the beginning of the universe into the realm of science…Hubble’s observations suggested that there was a time, called the big bang, when the universe was infinitesimally small and infinitely dense…One may say that time had a beginning at the big bang…(2).”
The 1965 discovery of the cosmic microwave background radiation, by Arno Penzias and Robert Wilson, provided compelling evidence for the big bang. What’s more, Hawking and Penrose showed that Einstein’s general relativity implied that the universe had a beginning.
The Theory of Everything advances the thought that if the universe had a beginning, then it had a creator. Afterward, without much in the way of explanation, the movie shows Hawking recanting his belief that the universe had a beginning. Instead, he proposes that the universe has no boundaries in space or time—i.e. no beginning, and no creation. He tells Jane that God is now out.
A Brief History of Time confirms Hawking’s change in view—that the universe did not have a beginning. He explains that combining general relativity with the uncertainty principle of quantum mechanics leads to black holes not being black, and the universe not having any singularities. Moreover, the universe “would neither be created nor destroyed. It would just be…What place, then, for a creator? ”
The movie does not address what impact, if any, Hawking’s new outlook may have had on his earlier work. Fortunately, Hawking explains in A Brief History of Time that his new proposal did not undo his earlier work on singularities. Rather, the real importance of the earlier singularity theorems was in showing that quantum gravitational effects could not be ignored in any grand unified theory. “…it seems that the uncertainty principle is a fundamental feature of the universe we live in. A successful unified theory must therefore necessarily incorporate this principle (2).”
Jane is deeply religious. Indeed, her faith helps to sustain her in caring for Stephen. [Despite Hawking’s fame and public acclaim, he was completely dependent on Jane at home.] In contrast, when Stephen refers to God, he seems to be making fun of Jane’s faith. Yet, Hawking does mention God often in A Brief History of Time. Moreover, the final words of the book are: “However, if we do discover a complete theory…then we should know the mind of God.”
In the movie, Jane discovers the above passage in Stephen’s manuscript. She then asks Stephen if he means it, adding, “Are you going to let me have this moment?” Stephen answers “yes” and “your welcome,” but he then adds, “However…”
Neither the movie, nor A Brief History of Time, tells us for sure what Hawking really believes about God. In any case, Hawking never suggests that he believes in a kind of supernatural creator that one might worship. So, it is likely that he refers to God in much the same spirit as Einstein did when he famously quipped, “God doesn’t play dice with the universe.” Einstein uses God as a religious metaphor, and I suspect that Hawking is doing the same.
Despite Hawking’s apparent agnosticism, he nevertheless seems uncertain as to whether science can ever explain existence. “What is it that breathes fire into the equations and makes a universe for them to describe? Why does the world go through all the bother of existing? Is the unified theory so compelling that it brings about its own existence? Or does it need a creator, and, if so, does he have any other effect on the universe? And who created him (2)?”
The following is from a piece by Caroline Graham and Gabrielle Donnolly in the Daily Mail (http://www.dailymail.co.uk/femail/article-2826974/Anguish-scientist-s-dumped-wife-revealed-star-Felicity-Jones-s-playing-movie.html#ixzz3lCV8caM4):
“British actress Felicity Jones – best known as the voice of Emma Grundy in The Archers, but whose film credits include Brideshead Revisited and the romcom Chalet Girl – plays the discarded wife and Eddie Redmayne, of Birdsong fame, plays Hawking.
During filming, Hawking and his ex-wife (Jane) both turned up on set. It was a daunting moment.
Felicity says: ‘Out of the corner of one eye I saw Jane and her new husband and out of the other eye I saw Stephen. It was probably one of the most intimidating moments of my life.
It must have been so bizarre for them to watch us playing them. It certainly felt awkward for me.’
Hawking and Jane watched a sequence during which Felicity and Redmayne danced together. After the director yelled ‘Cut’, Hawking – who communicates through a computer-based speech generator – asked: ‘Would you ask Felicity if she will come and give me a kiss?’
For 31-year-old Felicity, that moment was a revelation. ‘It shows his rather flirtatious nature and this amazing capacity he has not to take himself too seriously,’ she explains. ‘I embraced him and told him, “You’re amazing!” ’
(1) L.V. Anderson, How Accurate Is The Theory of Everything?, Slate’s culture blog, November 7, 2014.
(2) Stephen W. Hawking, A Brief History of Time, Bantam Books, 1988.
(3) “The Upright Thinkers”, Posted on the blog, August 19, 2015.