|Stephen Hawking in the 1980s|
On Tuesday, April 23, 1985, Hawking gave a talk titled "Why Time Goes Forward" at Mandel Hall at the University of Chicago. I was a freshman that year, and I was in the audience.
In 1985 (30 years ago!), Hawking was pretty much the figure you see on the cover of "A Brief History of Time," published three years later: wheelchair-bound, bone-thin, as twisted as tree roots. He spoke in a hoarse, squeaky whisper. Essentially unintelligible, except to people in his inner circle, he was accompanied on stage by an English graduate student, bluff and robust, albeit with slightly thinning blond hair, who "translated" him phrase by phrase.
It was like listening to an oracle. Hawking would laboriously emit 30 seconds or so of rasps and squawks. These were in fact sentences, well-crafted and dense with thought, which the grad student would render in plummy Oxbridge tones. There were some jokes mixed in. To my great elation, as the talk progressed and my ear grew attuned, I was able to discern a couple of phrases amid the squawks, confirmed by the ensuing repetition.
What I did not know until now is that Hawking lost his voice just a couple of months later. Via Wired's great article on Hawking's IT and voice synthesizer setup (HT The Browser), I learned that he caught pneumonia in summer 1985 while visiting CERN in Geneva, and had to have an emergency tracheotomy. Since then, according to Wired, his voice has been that of "Perfect Paul," a voice developed for an early text-to-speech synthesizer by an MIT engineer, Dennis Klatt, who used his own voice as a model.
I remember Hawking's Mandel Hall talk fairly well, which is good, because the journal entry I wrote afterward gives maddeningly little detail, (though I did note for posterity that the grad student sported a yellow necktie). Hawking began by showing us a short film of plates falling off a table, then ran the same film in reverse. In real life, shards don't leap off the floor and reassemble themselves into chinaware, but why not? You can't find time-directionality in physics equations as such. They're all time-symmetric.
That led into a discussion of the various "arrows" of time. Hawking mentioned three: the entropic (the direction of increasing disorder), the psychological (which points in the same direction as the entropic, since brain processes are physical processes) and the cosmic (the direction taken by the universe).
When the universe is expanding, the cosmic and entropic arrows point in the same direction. When the universe is contracting, however, entropy is decreasing, so the entropic arrow flips. This raises the unsettling possibility that sentient beings in a contracting universe could believe themselves to be living their lives forward from birth to death, making choices and controlling their fate, when in fact the universe is rolling serenely in the other direction scrolling them backward from death to birth. If that were the case, those sentient beings -- us, for example -- would never know the difference.
Hawking closed by suggesting that the universe could be a "smooth" space-time object, without a tell-tale singularity (i.e., the Big Bang) that you could point to and say, "This is where it started." It wouldn't need a beginning, it would just be.
Heady stuff -- "mind-blowing," says my skimpy journal entry. A lot of it is in "A Brief History of Time." How much of it physicists currently consider tenable, I haven't a clue.
A few years later, I listened to an audiobook narrated by Hawking in his synth-voice, and I remember thinking what an extraordinary evening that night at Mandel Hall had been. I now know I was even luckier than I realized.