Glory Road by Robert A. Heinlein

“Oscar, doesn’t this dinner and show, and possibly flowers, cost more than five dollars? Or even twenty? I understood that American prices were as high as French prices.”

“Well, yes, but you can’t just tip your hat and expect a girl to throw herself on her back. A tightwad–”

“I rest the case. All I was trying to show was that customs can be wildly different in different worlds.”

“That’s true, even on Earth. But–”

“Please, milord. I won’t argue the virtue of American women, nor was I criticizing. Had I been reared in America I think I would want at least an emerald bracelet rather than dinner and a show. But I was leading up to the subject of ‘natural law.’ Is not the invariability of natural” law an unproved assumption? Even on Earth?”

“Well–You haven’t stated it fairly. It’s an assumption, I suppose. But there has never been a case in which it failed to stand up.”

“No black swans? Could it not be that an observer who saw an exception preferred not to believe his eyes? Just as you do not want to believe that Igli ate himself even though you, my Hero, forced him to? Never mind. Let’s leave Socrates to his Xanthippe. Natural law may be invariable throughout a universe–seems to be, in rigid universes. But it is certain that natural laws vary from universe to universe–and believe this you must, milord, else neither of us will live long!”

I considered it. Damn it, where had Igli gone? “Most unsettling.”

“No more unsettling, once you get used to it, than shifting languages and customs as you shift countries. How many chemical elements are there on Earth?”

“Uh, ninety-two and a bunch of Johnny-Come-Latelies. A hundred and six or seven.”

“Much the same here. Nevertheless a chemist from Earth would suffer some shocks. The elements aren’t quite the same, nor do they behave quite the same way. H-bombs won’t work here and dynamite won’t explode.”

I said sharply, “Now wait! Are you telling me that electrons and protons aren’t the same here, to get down to basics?”

She shrugged. “Perhaps, perhaps not. What is an electron but a mathematical concept? Have you tasted one lately? Or put salt on the tail of a wavicle? Does it matter?”

“It damn well would matter. A man can starve as dead from lack of trace elements as from lack of bread.”

“True. In some universes we humans must carry food if we visit them–which we sometimes must, if only to change trains. But here, and in each of the universes and countless planets where we humans live, you need not worry; local food will nourish you. Of course, if you lived here many years, then went back to Earth and died soon after and an autopsy were done with fussiest microanalysis, the analyst might not believe his results. But your stomach wouldn’t care.”

I thought about this, my belly stuffed with wonderful food and the air around me sweet and good–certainly my body did not care if there were indeed the differences Star spoke of.

Then I recalled one aspect of life in which little differences cause big differences. I asked Star about it.

She looked blandly innocent. “Do you care, milord? You will be long gone before it matters to Doral. I thought your purpose these three days was simply to help me in my problem? With pleasure in your work, I realize–you threw yourself into the spirit of the occasion.”

“Damn it, quit pulling my leg! I did it to help you. But a man can’t help wondering.”

She slapped my thigh and laughed. “Oh, my very darling! Stop wondering; human races throughout the Universes can crossbreed. Some crosses fruit but seldom and some mule out. But this is not one of them. You will live on here, even if you never return. You’re not sterile; that was one of many things I checked when I examined your beautiful body in Nice. One is never sure how the dice will roll, but–I think the Doral will not be disappointed.”

She leaned toward me. “Would you give your physician data more accurate than that which Jocko sang? I might offer a statistical probability. Or even a Sight.”