The connection between matter and spirit has been debated for millennia. The central mystery is that certain material objects (human beings) contrive to be conscious and to possess a spiritual dimension. This implies that matter itself has some rudimentary spiritual character.

Daedalus reckons that the spiritual world occupies the same space as the material one, but at most points is very weakly coupled to it. Nonetheless, over cosmological space and time, this weak coupling must have brought the two realms into thermodynamic equilibrium. So the spirit world will have acquired the average temperature of the physical universe — 3 K, the temperature of the microwave background. (This explains why a ghost, an invasion of the material world by the spirit one, tends to cool the room.)

So Daedalus is looking for the weak thermodynamic coupling between the two worlds. A warm material object, even in a perfect vacuum and surrounded by a perfect reflector, should slowly cool down by thermal leakage into the spiritual world. The experiment will test modern thermometry and high-vacuum techniques to their limits; but success would open a whole new field of discovery.

Daedalus is already planning his exploration of it. He hopes to discover whether holy relics and ritual objects, imbued with spiritual significance, cool faster than more mundane ones. He expects that biological materials, especially the neurotransmitters and proteins of brain chemistry, will cool faster still. They are part of the secret of human consciousness, and should be quite tightly coupled to the spiritual world. This coupling might take the form of strong spectroscopic emission at the 3 K black-body peak in the millimetre-wave region, or it might be far more subtle. But detailed experiments, aided by such insights, should reveal the spiritual capacity of a wide range of objects and substances.

Perhaps the most interesting objects for testing will be semiconductors, either as bulk solids or in the form of integrated circuits and microprocessors. If they cool no faster than common minerals, this will demonstrate their lack of a spiritual dimension — in which case no computer, however powerful, could be conscious. But if they turn out to cool as fast as the neurotransmitters, then conscious technological monsters like Hal and Deep Thought should indeed be possible.