Despite years of effort, physicists have yet to unify gravity and quantum mechanics. The theory astronomers use to understand black holes is Einstein’s general theory of relativity. While nobody has directly observed event horizons for a variety of reasons (not least because they are very small, which makes it challenging even for big telescopes), astronomers have confirmed many predictions about their nature. The quantum character of black holes, however, is beyond reach for the foreseeable future: Few expect we’ll soon be able to observe the faint glow of Hawking radiation against stronger light sources.
Hawking’s own thinking about black holes has changed over time. That’s no criticism: Evidence in science often requires us to reassess our thinking. In this case, Hawking originally argued that black holes violated quantum mechanics by destroying information, then backed off from that assertion based on ideas derived from string theory (namely, the holographic principle). Not everyone agrees with his change of heart, though: The more recent model he used doesn’t correspond directly to our reality, and it may not have an analog for the universe we inhabit. The new talk suggests he has now moved on from both earlier ideas. That’s partly what raises doubts in my mind about the “no event horizons” proposal in the online summary. Is this based on our cosmos or yet another imaginary one of the sort physicists are fond of inventing to guide their thinking? In my reading, it’s hard to tell, and in the absence of a full explanation we are free to project our own feelings about both Hawking and his science onto the few details available.
Within physics, Hawking’s fame can seem kind of odd. Einstein made foundational contributions to both branches of modern physics—relativity and quantum mechanics—so his fame is assured. Hawking, on the other hand, works in a rarified subfield of gravitational physics, far removed from the realm of immediate testability. Most physicists don’t learn about Hawking radiation, singularity theorems, or black hole information paradoxes, yet outside academic departments Hawking is far better known than the architects of quantum physics, whose work underpins all of modern technology.
Hawking’s popular reputation was created through his best-selling book, A Brief History of Time, and the accompanying video program. Much of his fame is tied to a remarkable circumstance of his life: He has lived with amyotrophic lateral sclerosis for 50 years when few with the disease survive one-tenth of that time. Hawking’s electric wheelchair and attached computer that enables him to speak are as iconic as Einstein’s crazy hair.
In her excellent book Hawking Incorporated, Hélène Mialet examines the disconnect between the legend of Hawking the solitary genius of science and the reality of his life. That includes the entourage of people required to do everything from handling his bodily needs to assisting him with working out the mathematical equations he can no longer write down. These students and other assistants are not always credited by the public, even though their work is essential in translating Hawking’s thoughts into the symbolic form that is the language of theoretical physics. “The closer we get to the scientist’s [Hawking’s] body,” she writes, “the greater access we have to the extension of his distributed body: his assistants, computer, and students. Finally … we believe we have found the man because we are in the presence of his body, but that is when a multiplicity of Hawkings suddenly appears.” To put it another way, because of Hawking’s inability to communicate directly, we project our own feelings onto him.
That’s why it’s doubly necessary to separate Hawking the scientist from his science. Hawking isn’t a god among mortals; He has admitted to being wrong in his thinking in the past, so we shouldn’t assume everything he says is absolute truth now. He is an authority on black holes, but he’s not the only one—and there’s reason to believe we don’t know the whole story of his thinking on them now.
Such is the danger of celebrity in science, and why I think it’s a bad thing as a general rule. This paper becomes important not because of what it does or doesn’t say, but because A Famous Scientist wrote it. While the value of some scientific research is obvious immediately, the true worth of many theories is often unclear until later, after all the preliminary mess has been cleaned up.