We resumed the interview. The beam from the skylight had shifted to the east, leaving Mosala almost silhouetted against the window and a dazzling blue sky. When I invoked Witness again, it reached up into my retinas and made some adjustments, enabling me to register the fine details of her face in spite of the back-lighting.

I moved on to the question of Helen Wu’s analysis.

Mosala explained, “My TOE predicts the outcome of various experiments, given a detailed description of the apparatus involved: details which ‘betray’ clues about all the less-fundamental physics which – some people insist – a TOE is meant to pull out of thin air, all by itself. But unraveling those clues certainly isn’t trivial. You or I can’t just glance at an idle particle accelerator and predict, instantly, the outcome of any experiment which might be performed with the machine.”

“But a supercomputer, programmed with your TOE, can. So is that good, bad, or indifferent … are you guilty of circular logic, or not?”

Mosala seemed unsure of the verdict, herself. “Helen and I have been talking it over, trying to thrash out exactly what it means. I have to confess that I started out resenting what she was doing – and then ignoring most of her later work. Now, though … I’m beginning to find it very exciting.”

“Why?”

She hesitated. It was clear that her ideas on this were too new, too unformed; she really didn’t want to say anything more. But I waited patiently, without prompting her, and she finally relented.

“Ask yourself this: If Buzzo or Nishide can come up with a TOE in which the whole universe is more or less implicit in a detailed description of the Big Bang – details deduced, right here and now , from observations of helium abundance, galactic clustering, the cosmic background radiation, and so on – no one accuses them of circular logic. Feeding in the results of any number of ‘telescope experiments’ is fine, apparently. So why is it any more ‘circular’ to have a TOE in which the universe is implicit in the details of ten contemporary particle physics experiments?”

I said, “Okay. But isn’t Helen Wu saying that your equations have virtually no physical content at all? I mean, no amount of pure mathematics could ever produce Newton’s law of gravity – because there’s no purely mathematical reason why the inverse square law couldn’t be replaced by something different. The whole basis for it lies in the way the universe happens to work. Isn’t Wu trying to show that your TOE doesn’t rely on anything out there in the world – that it collapses into a lot of statements about numbers, which simply have to be true?”