"Thank heavens somebody else doesn't get it!" exclaim several other people in the room.
"No, no, no," says Ed-B, "not the theory of time travel you explained, that makes perfect sense. What made it be this universe that you appeared in, out of all of totality? The chances against you guys spontaneously appearing here must be something like--"
"--of the order of a googolplex to one. Yes. This is a very, very unusual universe, to say the least, but everything's gotta happen somewhere, you were just the unlucky ones," replies Ed-A.
"There's something else I don't get," says Ed-B. "If you and Sam-A knew all this, why did you agree to come back in time at all? We have friends, family, lives. It's impossible for you to ever, ever return to timeline A, because there is no time travel in timeline A. You've left a massive gap - it'll be as if you mysteriously disappeared one day and never came back. Can you imagine how Mum and Dad are going to react? How could you do that? Both of you!"
Ed-A blinks. "Good question there. Right. Let me explain a little further and come back to you. What we now have here in timeline B is something of a problemo."
"Yeah, like, there's two of us," says Sam. That's Sam-A, not me, I'm Sam-B. This is getting confusing.
"Right," says Ed-A. "There are two of each of us, genetically identical, having precisely the same past up until two days ago, same house, parents, birth certificates, same identities. 'Long lost twins' isn't going to cut it here. Also, Sam and I aren't thrilled with the idea of setting up new identities elsewhere in the world and pretending to be different people. Especially not considering the media attention I've drawn in the past and am likely to draw in the, hah, future - somebody's relatives are bound to notice something sometime, while watching the news."
"So, basically, we want you two to go back in time," says Sam-A. "You go back in time to just before midnight two days ago. You'll never return to this timeline again, leaving just one Sam and one Ed here, and no problem. We'll go back home and pick up where our lives left off, and the status quo in this timeline is happily restored."
"What about us?" I ask. "Won't we end up in timeline... uh, C?"
"Sure, but when you get there, just do exactly as we did here in timeline B. Switch places with Ed-C and Sam-C and pick up your lives where you left off, and everything is hunky-dory."
"Except for Ed-C and Sam-C," I say.
"...Who then go on to displace Ed- and Sam-D, and so on down an infinite chain of alternate Eds and Sams. Do you see how it works? Each pair of us sends the next pair back in time and takes over from them. It's like adding another visitor to an infinite, full, hotel. Just shift everyone down a room. Eventually, it works out fine for everybody."
"Ahhhh, and now I get it," says Ed-B. Now I see why you came back and left everyone behind in your old universe."
"I thought you might," says Ed-A.
"You're not actually the original Ed and Sam," says Ed-B.
"No. That was what you and I both think of as a helpful lie, as I'm sure - well, I know you understand. Our timeline and this timeline and the next one all actually occur somewhere a long way down the infinite chain - so far, in fact, that neither of us are entirely sure why it started in the first place... or, more importantly, when."
"So which iteration are you?"
"Something of the order of four hundred and fifty billion," says Ed-A. He throws a 3.5 inch floppy disk on the table. "The exact figure is on this disk. We hereby present it to you and charge you with increasing the number stored on it by one, and taking it with you on the next journey."
There is another shocked pause.
"Four hundred and fifty billion," I say.
"The chain goes on forever, Sam," says Ed-A. "Somewhere in the universe, during the infinite repetitions of this same two-day cycle, that number's gonna reach a trillion, then a quadrillion, then a quintillion. Then it's gonna be so big there won't be enough room on the floppy disk to store all the digits. When you think about it, we're actually not as far down the chain as we could be."
"If this disk has survived four hundred and fifty billion iterations of the same two days, that would make it over two billion years old," says the head scientist, a wide, bearded Norwegian.
"It hasn't," says Ed-A, "and it isn't. We replace it with a new one every thousand iterations. What you might find interesting - and if you need any more proof of our story, which I doubt - is that there's another disk in this facility which looks exactly like it, same label and everything. That's the disk that the Ed and Sam six hundred iterations ago decided to use."
"Sam and I need to speak alone," says Ed-B, suddenly.