“A young, recently very hot body,” Keene repeated.
“Exactly. And enough heat doesn’t get down to the surface in any case. In fact, hardly any does. For a start, most of the sunlight is reflected off the cloud tops thirty miles up—which is why Venus is so bright. And what does penetrate diminishes rapidly with depth in an atmosphere that thick, so that any solar heating you do get occurs at the top. Thermally it’s more like shallow seas on Earth, where sunlight is absorbed primarily in the upper three hundred feet. Venus’s surface pressure is about equivalent to that three thousand feet down in the ocean. Even at the equator, the temperature at that depth is only about eight degrees above freezing. You see, the greenhouse effect can’t simply be magnified without limit. Increasing the insulation also reduces the amount of sunshine that’s transmitted. Taking things beyond a certain point becomes self-defeating: The loss in transmission is no longer compensated for by the extra insulation, and the temperature begins to drop. None of the heat from the bottom of the ocean can escape into space, but it isn’t boiling hot.”
Keene thought it through but couldn’t fault it. He nodded for Salio to continue.
“This all fits with other things that have been known since the earliest U.S. and Russian space shots,” Salio said. “The planet isn’t in thermal equilibrium as the greenhouse explanation would require. It radiates twenty percent more energy out than falls on it from the Sun. Its dark side isn’t cooler, even though night lasts fifty-eight days. In fact, it’s slightly warmer. We’re talking about a planet with a lot of residual heat.”
“Has a cooling-curve model been worked out that’s consistent with this kind of temperature from an internal source?” Keene queried.
“Oh yes—and it’s quite interesting. If you start out with the assumption of an incandescent state three and a half thousand years ago, which is what the Kronians are saying, the calculated temperature today works out at seven-fifty degrees K—precisely what’s observed.”
“Why not radioactivity in the rocks?” Keene queried. “It warms us up here. Why not there too?”
“Generating ten thousand times more heat than Earth does?” Salio shook his head. “No way.”
Keene frowned as he thought back over what had been said. “And this has been known for years? . . . So why do we keep hearing the same story?”
Salio shrugged. “Once people are trained in a particular theory, they become emotionally wedded to it. They can be literally incapable of seeing anything that contradicts it, and will invent the most amazing rationalizations. That’s why you have to wait for a generation to die off before you can move on.”
“But how can that be?” Keene invited. “Science is objective, impartial, and self-correcting. All the textbooks say so.”
Salio returned a thin, humorless smile. It was clear that they spoke the same language. Keene sensed the way to real communication opening between them. It occurred to him what a lonely professional life Salio must lead. Salio went on, “And then you have the anomalies in atmospheric composition. For example, as most people know there’s the sulfuric acid in the upper clouds—probably formed out of sulfur trioxide from the hydrocarbon gases binding with what little water ever existed. But sulfuric acid in the cloud tops ought to have a short life due to decomposition by solar UV. If Venus were over four billion years old, there shouldn’t be any sulfuric acid left. But there is.
“The middle atmosphere is rich in carbon dioxide. That should have been dissociated in a few thousand years into carbon monoxide and oxygen, which don’t recombine again easily and ought to be abundant. They’re not.
“And where are Venus’s oceans? In billions of years it ought to have outgassed enormous volumes of water. The conventional explanation is that it was dissociated into oxygen, which combined with the rocks, and hydrogen, which escaped. But a lot of us can’t buy that. For one thing, the depth of surface you’d need to `garden’ to absorb the amount of oxygen indicated just isn’t credible. And for another, if dissociation produced oxygen, the oxygen should recombine into upper-atmosphere ozone the way it does on Earth, shutting out that UV band and terminating the process. How can you postulate one mechanism and ignore the other?”