“There’s a field of physics called quantum mechanics. It’s not specific to my own time. A chap called Max Planck kicked it off in nineteen hundred with something he called the quantum theory of light, and Albert Einstein moved it along in nineteen oh five with his work on the photoelectric effect. Basically, he theorized that light can be observed as either particles or waves, but never both at once. It’s all about uncertainty, gentlemen, what we call quantum uncertainty. Long story short? It’s most likely that there are an infinite number of universes, all existing alongside each other, all of them different, some subtly, some radically. I guess the fact that we’re here is the first real proof of that theory.”

“I’m sorry,” said Spruance, “but that sounds utterly ridiculous. You’re saying there’s a place where, for instance, America lost the War of Independence, or the South won the Civil War?”

“And infinite variations on that.” She nodded. “A universe where there was no War of Independence because British colonial policy was more enlightened. An American Civil War after which Lincoln wasn’t assassinated. A Second World War in which Hitler was. Or where the whole planet was invaded by, I don’t know, space lizards or something. A universe in which Coke tastes like Pepsi. And another in which I’m standing over there drinking tea, rather than here drinking this . . . uhm . . . coffee. You get the picture?”

“If that’s so,” mused Spruance, “it might seem as if you’ve dropped into your past, but in truth you haven’t.”

“Quite so.” Halabi nodded, encouraged by the man’s grasp of the theory. “This may be a subtly different nineteen forty-two. Or maybe a radically different one. Perhaps Hitler doesn’t make the mistake of invading the Soviet Union . . .”

“He has,” Beanland put in.

“Oh. Well, that’s good then. But you’re right, Admiral. Maybe things are slightly different here. Maybe nothing we’ll ever notice, like the typeface of a small county newspaper being altered, but everything else appears exactly the same. Or maybe our trip here was a straight H. G. Wells deal. From twenty twenty-one to our very own nineteen forty-two. I don’t know. We may never know. Theories are one thing, but actually cracking open the fabric of spacetime and manipulating it without dire consequences, well, that’s a whole other sort of something.”

“As you may have discovered to our cost,” said Spruance.

“Yes,” Halabi admitted. “I am sorry. You were unfortunate enough to tangle with our CIs while there was minimal human oversight.”

“CIs?”

“Combat Intelligences. Computers. Machines that think. They help us run our ships, our whole society actually. And when they detected the threat you posed to the task force with your cannon fire, they responded.”

“Well, that response may have cost us the war,” Spruance observed bitterly.