I admit though that, before I watched the programme, I was excited about it all day; in the best of all worlds I was hoping to hear some commentary on Hawking's most recent paper, perhaps even some insights that might help me understand it. But alas not. The programme aired at 9pm on BBC2 yesterday, and my spirits immediately sank when the announcer introduced it as "the reputation of the world's most famous scientist at stake". The first images we see are from a beach and there's a wall with at least 6ft high graffiti on it, and the largest graffito of all is of Hawking's equation relating entropy and event-horizon area. Perhaps this was also meant to draw parallels with graffiti of E=mc^2, who knows? The voice over begins, and the camera ranges over the beach to an astrologer:
"What if the world were so strange we could never hope to understand it and science was wasting its time? It sounds like the sort of thing a mystic might say but this was a suggestion made three decades ago by the most famous scientist in the world, Stephen Hawking."From then on one had the idea that the scientific story was going to lag behind the human story, but, for pity's sake, why?
The introduction focussed on Hawking's celebrity, with Kip Thorne saying of him:
"He's absolutely unique, and I think he has been a very important person in both the intellectual and the cultural life of the past century."These fair comments were countered by the voice-over's,
"But recently doubts have been expressed by some physicists about Hawking's scientific reputation."Thereby initiating the main story being addressed by Horizon, that perhaps Hawking ain't so great. Frankly this appeared as unfounded, unsupported and scurrilous journalism used to appeal to a wider audience, and at no stage were any of Hawking's conributions to physics not related to information loss discussed.
The information loss paradox was described as the result of a black-hole evaporating to nothing leaving behind only thermal radiation, i.e. carrying no information. That there would be a problem even if the black-hole didn't disappear was not made clear
(There is clarification about where this is a concern from Christophe Galfard in the comments). Without recourse to quantum mechanics this was described as a violation of one of the most fundamental principles of physics, that information is never destroyed. The voice over spookily summarised,
"Effectively bits of the universe are missing...nothing science knows not even our memories could be trusted."Lawrence Krauss commented, probably to the delight of the Council for making Science Scary who seem to be in charge of Horizon,
"...at its most extreme scale what it means is everything you come to know and love would ultimately disappear."This scary comment went without any guiding timescales.
Cue Leonard Susskind who was presented as Hawking's adversary in an immense intellectual battle. Susskind described how he felt a need to resolve how it was that one could watch someone cross into an event horizon and potentially be pulled apart, while the same person would feel no great change as they themselves fell across the horizon. Ah, a good old-fashioned change to Eddington-Finkelstein coordinates, at last some firm ground. The voice-over's interpretation of this coordinate change:
"The same equations were saying that someone could be both dead and alive."Hmph. Susskind described his resolution that allowed both of these possibilities to coexist and resolved the information loss paradox: holography. That the black hole acts like an information projector and that anything that falls into it has its information "beamed" onto the lower-dimensional event-horizon, thus avoiding losing information inside the event horizon. Although quite what was going to happen to the information when the black hole evaporated was not addressed. Susskind's belief's were presented as being vindicated by Maldacena's paper, Eternal Black Holes in AdS. And finally the programme concluded after the Dublin conference where Hawking conceded that information was preserved. So, no chance of an explanation of the sum-over-topologies approach, ho-hum. There is some commentary by Lubos Motl on the paper Information Loss in Black Holes, and if you are interested in holography you could read TASI lectures on the Holographic PrincipleTASI lectures on holography by Bigatti and Susskind.
Of course despite my disappointment with the lack of theory, the human story was appealing. There were some very nice pieces of footage of Hawking working with his students. In one shot, prior to adopting his synthesiser, Hawking is seen talking to what looks like a seminar with the help of a student, Chris Hull. Chris Hull says that they happen to have a model of the universe with them and pulls out a cylinder and puts it on a table in front of the audience. Hawking makes some comments and grins, the student scratches his head and then turns the cylinder the other way up. It is identicle both ways.
Also, there were some encouraging comments about the trials of a student from Christophe Galfard, who, contrary to my earlier scandalous comments, has pointed out that he does not work in the signature (+---), described the start of his PhD with Hawking, saying:
"For the first year-and-a-half every sentence of Stephen's took me about six months to understand."And of reading Maldacena's paper:
"I took a little while to read it, a little while being about a year-and-a-half."Again: here, here!
The show ended with Hawking saying:
"I have no intention of stopping anytime soon. I want to understand the universe and answer the big questions, that is what keeps me going."At no point did the programme mention the word string, nor topology! Is this really the best way to promote science to a popular audience? Could it not be done with at least a little humour, and less of the portentous voice over? Maybe even less of the human-interest story? After all the science is fascinating if communicated well. Oh for a more perfect world.