But he didn't sound like a contented man. Maybe it wasn't Bloom's wealth alone that irked Priss; maybe it was Bloom's fame among the people of Earth generally; maybe it was the fact that Bloom was a celebrity wherever he went, where as Priss, outside scientific conventions and faculty clubs, was largely anonymous.
I can't say how much of all this was in my eyes or in the way I wrinkled the creases in my forehead, but Priss went on to say, 'But we're friends, you know. We play billiards once or twice a week. I beat him regularly.'
(I never published that statement. I checked it with Bloom, who made a long counterstatement that began: 'He beats me at billiards. That jackass--' and grew increasingly personal thereafter. As a matter of fact, neither one was a novice at billiards. I watched them play once for a short while, after the statement and counterstatement, and both handled the cue with professional aplomb. What's more, both played for blood, and there was no friendship in the game that I could see.) I said, 'Would you care to predict whether Bloom will manage to build an anti-gravity device?'
'You mean would I commit myself to anything? Hmm. Well, let's consider, young man. Just what do we mean by anti-gravity? Our conception of gravity is built around Einstein's General Theory of Relativity, which is now a century and a half old but which, within its limits, remains firm. We can picture it--'
I listened politely. I'd heard Priss on the subject before, but if I was to get anything out of him-which wasn't certain-I'd have to let him work his way through in his own way.
'We can picture it,' he said, 'by imagining the Universe to be a flat, thin, superflexible sheet of untearable rubber. If we picture mass as being associated with weight, as it is on the surface of the Earth, then we would expect a mass, resting upon the rubber sheet, to make an indentation. The greater the mass, the deeper the indentation.
'In the actual Universe,' he went on, 'all sorts of masses exist, and so our rubber sheet must be pictured as riddled with indentations. Any object rolling along the sheet would dip into and out of the indentations it passed, veering and changing direction as it did so. It is this veer and change of direction that we interpret as demonstrating the existence of a force of gravity. If the moving object comes close enough to the center of the indentation and is moving slowly enough, it gets trapped and whirls round and round that indentation. In the absence of friction, it keeps up that whirl forever. In other words, what Isaac Newton interpreted as a force, Albert Einstein interpreted as geometrical distortion.'
He paused at this point. He had been speaking fairly fluently-for him-since he was saying something he had said often before. But now he began to pick his way.
He said, 'So in trying to produce anti-gravity, we are trying to alter the geometry of the Universe. If we carry on our metaphor, we are trying to straighten out the indented rubber sheet. We could imagine ourselves getting under the indenting mass and lifting it upward, supporting it so as to prevent it from making an indentation. If we make the rubber sheet flat in that way, then we create a Universe-or at least a portion of the Universe-in which gravity doesn't exist. A rolling body would pass the non-indenting mass without altering its direction of travel a bit, and we could interpret this as meaning that the mass was exerting no gravitational force. In order to accomplish this feat, however, we need a mass equivalent to the indenting mass. To produce anti-gravity on Earth in this way, we would have to make use of a mass equal to that of Earth and poise it above our heads, so to speak.'
I interrupted him. 'But your Two-field Theory--'
'Exactly. General Relativity does not explain both the gravitational field and the electromagnetic field in a single set of equations. Einstein spent half his life searching for that single set-for a Unified Field Theory-and failed. All who followed Einstein also failed. I, however, began with the assumption that there were two fields that could not be unified and followed the consequences, which I can explain, in part, in terms of the "rubber sheet" metaphor.'
Now we came to something I wasn't sure I had ever heard before. 'How does that go?' I asked.