… Name of Jackson and Ryan
As I was saying, Al Jackson never forgot Willy Ley’s Tunguska tales, and thirteen years later he shared them with a fellow U Texas grad student, Mike Ryan.
So it was only natural that, when Al came across Stephen Hawking’s first paper on primordial black holes, that he’d casually ask Mike: “What about the Tunguska Event being due to a primordial black hole”?
Here’s how Mike remembers that fateful meeting: — Ladies and gents, Dr. Michael P. Ryan, Jr.:
The thing is that Al has a tremendous imagination. He can see all kinds of connections in things, and very strange connections occasionally. And he would come into my office at Austin and he would say: I’ve solved this problem — I know it’s this. And so my first reaction was: let us calculate.
And we would calculate, and find out that it just didn’t work at all.
And so one day he came in and he said: I’ve solved the Tunguska problem — it’s a small black hole.
And I said: let us calculate.
So they calculated.
It was pretty easy to see how much energy would be deposited in a shock wave due to a gravitating body moving through the atmosphere faster than the speed of sound. Sure enough, about an asteroid’s worth of mass in a package the size of a molecule would do the trick.
Weighing in at a quadrillion tons or so — black holes are very massive, remember: even the tiny ones pack a big punch! — the microscopic black hole would produce all the observed Tunguska effects (bright blue “tube,” megaton-scale explosion, total devastation) from gravitational interactions alone.
Here’s Mike again:
And we calculated, and the energy that it deposited came out to be more or less all right.
So, Al and Mike could pretty much match up their calculations with the Tunguska eyewitness accounts of the impact itself. Figuring what would happen after that was trickier. Once the thing hit the earth, it should’ve kept on going. With its tiny diameter and gargantuan mass, the primordial black hole would’ve sliced through solid rock as if it wasn’t even there. In fact, it should’ve plowed straight through the earth and come rocketing up out the other side and gone sailing off into outer space again.
But …
… Not before producing the same sorts of effects at the exit as it had at the original point of impact. In fact, as Al and Mike would write in their Nature article, “This exit provides a check for the whole hypothesis.” In other words, all you had to do was look for a second set of shockwaves and earthquakes an hour or so after the first ones.
But look where? Where would the thing have come out?
The way Mike told it to me, he and Al used the best azimuth they could find, calculated the distance through the Earth for the angle of entry, then used the high-tech method of stretching a string … on a globe someone had in their office.
It’s fun to picture that: Sort of like a low-budget remake of that scene in Close Encounters of the Third Kind, where the NASA guys roll this big globe down the hall and use it to find the latitude and longitude of Devil’s Tower, Wyoming.
But it worked, gave them the answer they were looking for: The exit event would have been out in the Atlantic, northwest of the Azores. And since — as Al and Mike had claimed — “This exit provides a check for the whole hypothesis,” all you’d need to do to test the theory was just check the shipping records for end of June 1908.
By this time, spring semester was over, and Mike was packing up to spend a summer at Oxford. Before he left, he and Al talked about the Tunguska idea a couple more times, and Mike suggested they write it up:
And so I said: I can’t resist this — we’ve got to write
a paper about it. And do it real fast and send it off, just as something fun and interesting.
By June of 1973 Al had done just that: sat down and worked through the calculations again and sent them off in a letter to Mike for some final word-polishing and equation-checking. As Mike says:
So we wrote it up and sent it off, and we sent it to Nature, and strangely enough Nature accepted it, which surprised me. So, I assumed it was completely finished and nothing would ever happen.
And then all of a sudden these things like the CBS News, New York Times, London Times, Time magazine …
If Mike was surprised, Al was shocked — he was getting phone calls from Time magazine before he even found out the paper had been published. He and Mike got their fifteen minutes of fame — or maybe notoriety is a better word.
But Al does have one good memory of that brief moment in the spotlight. As he told it to me:
Stephen Hawking had come to U Texas in the fall of 1974 for that year’s Texas Relativistic Astrophysics Conference. So at the conference Al walked on up to Hawking and introduced himself. Unfortunately, this was at a time after Hawking had lost the power of speech but before he got his speech synthesizer, so he needed his graduate assistant to “translate” for him, and the translator was nowhere to be found. Anyway, Hawking seemed to recognize Al’s name, motioned him down and said something to him.
As Al remembers it:
I didn’t understand a word. He obviously knew of the paper, but I don’t know if he said “that was an interesting paper” or “what a piece of crap!” To this day I have no idea what he said!
But, if Al’s crowning moment with Stephen Hawking ended up kind of ambiguous, the reaction of the physics community at large would be anything but. And “what a piece of crap!” would be the least of it!
Or, as Mike Ryan put it:
… the CBS News, New York Times, London Times, Time magazine — and even a Sunday science comic strip had this in it with, the Sunday science comic strip showed some Siberian peasants running away and this huge explosion behind them.
And I knew we were in trouble.
And trouble wasn’t long in coming.
What kind of trouble? Well, we’ll get into that one next time.
References
All quotes from Al Jackson and Mike Ryan are courtesy of Albert A. Jackson, IV and Michael P. Ryan, Jr., as recorded at the Johnson Space Center Amateur Astronomical Society meeting and Singularity launch party, November 2004.
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