Eventually we find an unused interrogation room. I sit in one of the chairs while Ed paces about.
"I don't mind telling you, Sam, this is getting seriously scary," says Ed to me. That was the last thing I needed to hear. Pretty much everything Ed has ever done - the hoop wormhole, the messages woven into the fabric of reality, the switch - has scared me to a greater or lesser extent. But Ed has never been the least bit fazed by his experiments. He always comes up smiling. Until today I kinda thought that was because he was slightly insane.
But Ed is scared too. Ed, destroyer of galaxies, creator of microscopic universes.
"Why?" I ask, against my better judgement.
"The first thing I want to know is why we travelled back in time in the first place. What happens in our future which is so bad that we are willing to leave behind everyone we hold dear and become time travellers? A lot can happen in four hundred and fifty billion iterations of the same two days. Heck, I bet at least a few dozen of us have broken our legs stepping out of the time machine, just by chance. But if the very first Ed and Sam were anything like us, it's possible that what happened to them could happen again, to us. We don't even know how far into the future the first Ed and Sam came back from - it could be a day or a year or a hundred. Is a nuclear war on the cards, or something worse?
"The second thing that worries me is the extent to which our past selves could be lying to us. Even discounting the distortion that even the most carefully-reproduced truths will experience after being copied a half-trillion times, when we look at ourselves, how trustworthy do we seem? Do you think it's likely that at some point in however many iterations, Ed and Sam impulsively decided to spin a web of lies to the next Ed and Sam, chose a number at random, stuck it on a disk and forwarded it to them? And that could have happened a million iterations back. The lie could have been forwarded so many times that neither us nor Ed-A and Sam-A nor the Ed and Sam preceding them even had an inkling of the real truth."
"I wouldn't lie," I volunteer.
"Wouldn't you? Think about chaos theory. The arrival of our alternate selves and the events proceeding on from then can be subtly different in an unimaginable number of ways. Surely it wouldn't be too improbable that the exact circumstances might come about that would persuade us to lie? Even to ourselves?" Ed sees my utterly confused look. "Trust me, it's possible.
"Lastly, I'm not even sure that those two people ARE you and me."
"Oh, come on, now that's just paranoia! What would the Kerrig Facility scientists stand to gain from such deception? They look EXACTLY like us. Their clothes are exact duplicates of ours even down to the little rips and tears. Their speech and mannerisms are ours, although to be honest I didn't think my voice sounded that silly, and they know everything we know - you saw the DNA test results."
"Come on, Sam, I know how to clone people! They could have ripped the cloning technology right from my own computer! And you of all people know how much of a threat to society I am; the odds of me flipping out, deciding to conquer the planet and actually pulling it off are much too risky. Putting me away for good, by means of vaporizing me in that disintegrator-cum-'time machine', would be good for world safety. No, we need some way to be certain."
"Well, how about the time travel passwords?"
Ed claps his hands together. "Brilliant! I should have thought of that!" He rushes to the door and opens it--
Standing outside are Sam-A and Ed-A. "Your time travel password is the phrase 'Laser Squid Nemesis,' says Sam-A to me.
"Yours is a symbol: a Greek capital phi with a square instead of a circle," says Ed-A to Ed. "We were as paranoid as you were. We came to the exact same room and probably had a very similar conversation."
"There's no way you can prove that jazz about there being billions of iterations of us. There's no way the previous Ed and Sam could have proved it to you, for that matter."
"Right, and they didn't. We took it on trust. If we can't trust ourselves, who can we trust?" asks Sam-A.
After an uneasy pause, I eventually relent. "Well, I trust me."
"I guess so," says Ed-B, reluctantly, eyeing his counterpart suspiciously. "Alright. Give us the disk."
All this is happening so fast that we might even be able to get back to the UK before the serious jet lag sets in. We have a much-needed meal at the Kerrig Facility canteen and then head back to the time machine room.
Using the (digital) blueprints and technical readouts that Ed-A brought from the previous timeline - blueprints which we KNOW work perfectly due to the fact that both they and their couriers made it here intact - the Kerrig scientists have successfully configured what they are 99.999% sure is a working time machine, capable of admitting the two of us safely. A digital copy of the 'prints has been made and we're taking it back with us, along with the floppy disk and its recently-incremented and possibly arbitrary number.
Ed and I slouch in what is, indeed, a cannibalised elevator car, while around us final checks are made and the component which - while technically containing nothing more entertaining than an Io-worthy quantity of electrical energy - has been affectionately dubbed the "flux capacitor" starts charging.
The final countdown starts. Ed-A and Sam-A have informed us of exactly what to expect in around sixty seconds' time, when we will - if all goes to plan - materialise uninvited in the centre of an incredibly secret scientific installation, set off several alarms and attract the attention of a dozen gun-toting US marines. They say that holding our arms up and saying "we surrender" might be a good idea.
"When are we coming out, exactly?" I ask Ed.
"Well, sending us back to anytime after Ed- and Sam-A appeared in this timeline would only complicate matters unimaginably further, by introducing a third pair of us. Sending us back to the exact time they appeared runs an uncertain risk of us being annihilated by them - or vice-versa - as both of us attempt to materialise in the same location at the same time. So instead we're going back a little further - one nanosecond, to be precise. It's all determined by atomic clocks so there's nothing to worry about on the accuracy front."
"What if they appear right after we do?"
"A googolplex to one."
"Hey you guys," says a voice which seems to be coming over the intercom. It's Sam-A. "I just wanted to say, it was pretty cool running into an alternate set of us. Both times. Although the second time is much more enjoyable since you already know what happens, mostly. You'll find out for yourself in about sixteen seconds."
There's a digital readout in the transport chamber, and I glance at it as it ticks downwards. Fifteen. Fourteen. "Yeah," adds Ed-A. "I've got one more piece of advice for my counterpart, though." Ed-B, our Ed, stands up and peers through the tiny window at Ed-A. The intercom is one-way but they still have visual contact, at least. Eight. Seven. "Ed, you listen to this very carefully... are you listening?" Five.
Ed-B nods. Four. Three.
"DON'T MARRY JEN."