'Gentlemen,' cut in Plumps from the side of the room where he had been standing, 'I'm impressed with the virtuosity of your arguments, but I'm still very disturbed at the nature of your conclusions. Doesn't anyone have an alternative suggestion?'
The question was greeted with silence. Runyan stood mute. His eye rested on, but barely registered, a dollop of coffee on the desk, spilled from a cup Gantt had brought in after lunch. His fixation was broken by Ted Noldt who stirred and said, 'I have a question which bears on the possibility of a black hole.'
Runyan lifted his eyes and looked at the speaker. 'I don't know much about black holes,' Noldt said, 'but I thought the small ones, about which you are talking, were supposed to radiate away their mass and energy at a great rate, causing them to evaporate and explode. Doesn't that rule out such a black hole?'
'We're going to have to consult a real expert on the subject, which I'm surely not,' replied Runyan. 'That question has been very much on my mind.' He paused a moment and then continued. 'Here's a possibility. The theory of evaporating black holes was worked out in the context of idealized, empty space, whereas this one's in the real world!' He caught himself. 'Sorry. A grotesque pun. Unintentional. Anyway, maybe the fact that this one is surrounded by matter changes things.'
'That may be right,' mused Fletcher, picking up the argument. 'If it's consuming matter, the infall may squelch the outflow. Let's see, didn't you and Ellison estimate the rate of consumption just now?'
'Right,' said Runyan, turning to the board once more. 'I don't remember all the formulae for the evaporation rate, but maybe I can piece something together.' He doodled for a minute while the others looked on and listened to the scratching chalk. 'Yes!' he looked up. 'That's probably it: there seems to be a comfortable margin. As long as the hole bores through the earth, it will eat the matter and grow. You'd have to stop the consumption to get it to evaporate.'
'Wait a minute,' said Noldt, punching a finger in the air. 'That's not really relevant, is it? This flung must have come from space somehow, so it must be massive enough not to have evaporated before it got caught in the earth. Isn't that right?'
Runyan beetled his brows at Noldt and paced along the narrow corridor in front of the blackboard a couple of tunes. Then he turned to face him again.
'No,' he said, 'I'm not sure that is right. It's true that the cosmologists have told us about the possibility of such mini— black holes created in the turbulence of the Big Bang. But there are two problems. In the first place, though my estimates are crude, I don't believe this object is massive enough to have survived since the beginning of time. Secondly, there is a great difficulty with the curious fact that it moves with the earth.'
'What's that?' Noldt was puzzled.
'If this were a black hole born in space,' Runyan explained, 'there is little chance that it could get trapped in the puny gravity of the earth. For that to happen, it would have to be moving very slowly with respect to the earth. But what with the earth's motion around the sun and the sun's motion around the galaxy and the galaxy's motion off to god knows where, the relative speed between the earth and any random astronomical body would be much greater than the escape velocity from the earth. The earth could not possibly attract and hold anything moving past it so rapidly.
'Do you remember the Tungus event?' he asked Noldt. Noldt had to think for a second, "fungus? Russia. Siberia ! Big explosion?'
'Right,' Runyan replied. 'Still rather mysterious. Some explosion in Siberia in 1919. Burned and flattened trees for miles around. But no crater. That ruled out a large meteorite. Any piece of space rock big enough to do the damage done would have to have left a crater rivalling the old one in Arizona. The best idea seems to be a comet. Comets are thought to be very loose fragmentary icy structures. Such a thing could deliver a hell of an impact but be sufficiently diffuse not to gouge a crater.'
'So?' Noldt did not see the point.
'Well, whenever something strange happens somewhere, someone is going to suggest a black hole.' He broke off and looked at Leems scowling at him. 'I know what you're thinking, Harvey. If the shoe fits... But hear me out.
'There was a suggestion that the Tungus event was caused by a small black hole. Then it would just dig a small tunnel as I've described, not make a large crater.
'This idea was quickly ruled out though, for just the reason I said. Any black hole coming in from space would have to be moving at a huge velocity, at least a hundred times greater than we're dealing with here. The question earl raised a minute ago is pertinent. Such velocities are supersonic and the hole arrives with a large shock wave. That's what was supposed to cause the Tungus blast itself. But then when the hole went through the earth it would have generated seismic waves that would have pinned seismographs all over the earth, and while the 'Fungus event itself was registered, nothing like the passage of a supersonic black hole occurred.
'Finally, you can trace the angle of impact from the pattern of flattening of the trees. Any such black hole should have reemerged in the Baltic Sea and blown Norwegian fishing boats out of the water. From all reports, they fished peacefully that day.
'So the hypothesis of a black hole from space ultimately made no sense there.' Runyan looked directly at Noldt again. 'And it makes no sense here either for the same reasons. The velocity would be too high. But whereas a low speed black hole would not have caused the Tungus event, a low speed black hole fits what we've seen here.' He nodded towards Isaacs and Danielson.
Noldt thought for a moment. 'Well,' he said, 'suppose the universe is littered with these things, and we just happened to have the bad luck to finally overtake one slowly, and it settled in.'
'We don't know anything about the distribution of such holes in space, of course,' said Runyan. 'No evidence for them has ever been observed. To have enough small black holes to make the interaction you describe probable, I would think they would have to be so densely distributed that we would have noticed many other astronomical effects.'
'I don't understand what you are saying,' stated Noldt.
'What is the alternative? Surely such a thing doesn't occur spontaneously on earth?'
'No, I don't see how it possibly could,' agreed Runyan.
'I don't see how it could have occurred naturally on or off of the earth.' He paused, unable to avoid sounding portentous, and somewhat embarrassed at doing so. He was determined not to speak next.
After a moment, Leems spoke up with an edge in his voice. 'If we accept your arguments up to this point, then we're forced to the conclusion that this thing was manufactured. Is that what you're saying?'
Runyan nodded, but remained silent as all eyes shifted towards him. At last he said, 'That's the second conclusion I've reached. I think we must allow for the possibility unless it can be rigorously ruled out.'
Again Runyan became silent as he exchanged glances with his colleagues, desiring to support, but not lead the discussion at this critical juncture.
'There are two possibilities then, aren't there?' asked Fletcher. 'It's man-made or...' He paused and finally said in a flat voice, 'Or it's not.'
'Omigod!' exclaimed Noldt. 'You mean this thing could have been manufactured by extraterrestrials and... and planted here?'
Several voices were raised in simultaneous protest.