Hawking, Easterbrook, the arrow of time and black holes

Brad DeLong, who is an economist by trade, nevertheless knows enough about physics and cosmology to completely rip apart Gregg Easterbrook's inane ranting about Stephen Hawking (which is, itself, behind a subscriber wall, so I admit I haven't read all of it, but the part he quotes is infuriating enough).

Much as Chad Orzel said a while ago (correction: my bad, it was Sean Carroll), I'm ambivalent about Hawking's celebrity status. Unlike DeLong, I actually think that A Brief History of Time was an overrated book: not as good as previous efforts at explaining the basics of modern physics to laypeople, and too abbreviated and obscure when it came to the interesting and abstruse stuff that Hawking was actually working on at the time. And the tone of certainty in Hawking's occasional major public pronouncements can be irritating, when the actual reasoning behind them relies on speculative assumptions.

But this neo-John Lukacs blather from Easterbrook about how he's just making up gibberish is far worse. In addition to the reasons that DeLong explains, there's the fact that, as far as I can tell, Easterbrook doesn't even get Hawking's own statements right.

From this and other quotes of the Easterbrook article, it appears that he says Hawking claimed in Brief History that someday the universe will start contracting, at which point time will start to run backward. This is an infuriatingly frequent and almost 100% reversed misquote of Hawking's book. Hawking said in the book that he had once believed that the arrow of time would reverse, but no longer did, and in fact had a solid argument that it was not true! (An argument, furthermore, about which many other cosmologists were skeptical, if I recall correctly.)

As for the business about black holes, Hawking's recent reversal has absolutely nothing to do with whether they "crush reality out of existence" or "are doorways to alternate universes". It has to do with a specific technical issue of interest to quantum cosmologists and quantum-gravity theorists, namely, whether black holes that evaporate are, or are not, compatible with the specific kind of time evolution of states that exists in the standard formalism of quantum mechanics, which allows information to be scrambled but not destroyed. Hawking's preferred answer used to be "no" but is now "yes". His reasoning has to do with stuff I don't entirely understand, concerning how one applies quantum mechanics to a space-time whose topology could change.

The closest work of Hawking's I know to what Easterbrook is going on about—the doorways to the universes and the crushing of the reality and the glavin and the hey-hey—is his classic work with Roger Penrose on singularity theorems and the classification of large-scale solutions to classical general relativity. That work still stands within its non-quantum domain of application.

Just Add Water

Months went by before anyone noticed, because ocean shipping avoided the Splash Zones. The shaped chunks of Moon rock weren't quite meteors; they'd been dropped from a dead stop at 100 kilometers, by the rotating orbital cables for which they served as counterweights. Still, that's a long way to fall, and you don't want to be anywhere near when one comes down.

When boats started to disappear, and the alvins sent back disturbing pictures from the sea floor, I paid a visit to the Thanh and Company ballast mine in western Oceanus Procellarum. One of their rocks was doubtless at the other end of the cable that flung my moonliner on its way.

It was all automated: boulders robotically strip-mined, sandblasted into crude entry vehicles and loaded onto the electromagnetic mass driver that shot them toward Earth, untouched by human hands. There was a staff of twelve in a spartan pressure vessel.

I bothered everybody and waved the photos and sonar maps in their faces. This is the kind of thing you can't do on the phone; they might not put the right guy on the line. Finally, the assistant maintenance tech for the mine bots started talking.

"Didn't want to rock the boat," he said. "Come outside and I'll show you."

In cross-section it looked tubular, full of blobs and veins. It was sliced in two, the glassy, frozen surface gleaming in the soft trench lighting. There were more on the other wall of the trench; those had shriveled in the lunar sunlight, and left hollows in the rock in inverse image. There was a suggestion of branching limbs, bulbous protrusions, antennae.

The resulting tunnels were ten to twenty meters wide.

"The bots uncovered these within the past... half a year or so," I said.

"Yes."

"How big do they get?"

"Who knows?"

They were dead, that was clear. Sliced into pieces. But inside them... frozen eggs?

"How old are these rocks?"

"Not so old. 1.3... 1.4 billion years."

"Volcanic flows, right?... The Moon would already have been airless and dead."

He nodded. "Who knows how they got here? Somebody put them here? Damned if I can figure it out."

Silently, we took the service elevator back to our crawler and climbed in, as robots drove silently by. I raised my eyes to Earth, a crescent now, low in the black sky. What were we in for?