"So I've got this time machine, only it's not really a time machine because instead of travelling through time you're sent to another universe that looks a whole lot like the past, because in the Multiverse, anything is possible. Have you ever seen Sliders?"
"Yeah. Fun show. The Multiverse machine sounds cool, though. There won't be any butterfly effect paradoxes or anything like that if you're just travelling to another universe instead of another time. That's cool."
"Oh, no. Actually, you can change the past. Earlier in the book there was some dude who traveled to the Multiverse version of the 1300's and left a message for all his historian pals to dig up later in this universe."
"How'd he do that?"
"How should I know? I only built the thing. Maybe it really is a time machine. By the way, there's no such thing as a paradox. That's total bullshit. They don't exist."
"I'm a little lost. I thought you were selling me on the idea of a Multiverse machine."
"Shut up for a second. I'm trying to explain paradoxes, which don't actually exist because it's really, really hard to do something that would cause a paradox. Like, how could you possibly kill your grandfather? Wouldn't that affect you morally? Like, wouldn't you bitch out before you could pull the trigger? And what if he had armed guards? And even if you did, it doesn't matter in the grand scheme of things, so it doesn't really count as a paradox. That makes sense. By the way, I'm the smartest character in the novel. We established that very early in the book."
"Okay. How does it work? Do I stand right here?"
"Yeah. Perfect. Now we're going to scan your body with super-computers, collect your sub-atomic information in a bunch of JPEG files, and then we'll send your information through the Multiverse, just like a fax machine. Have you ever used a fax machine, before?"
"What year was this book written?"
"Recent enough to know better. Are you ready for the laser?"
"Wait. What laser?"
"The laser that's going to kill you, of course. Right down to the atom."
"How does that help me travel through time? Multiverse. Whatever."
"The laser is going to kill you because the Multiverse has these weird equivalent exchange rules that I'm never going to bother explaining. If we kill you here then the Multiverse will make a duplicate version of you in the universe we're contacting."
"I don't get it. What's with all the JPEG scanning? Aren't you going to send that data through the Multiverse and replicate me somewhere else?"
"We're going to fax the data, and yes, that's the idea."
"So why kill me?"
"I just told you that I wasn't going to explain how the Multiverse works. Now do you want to time travel or not?"
"But I wouldn't even be the one time travelling. It'd just be some JPEG version of myself, which I'm still confused about."
"Hey. Don't be a bitch. The fax doppelganger version of yourself will think he's you in every conceivable way. To any outside observer, you're exactly the same person."
"But I'm not an outside observer."
"No shit. Why do you think I only send other people into the time machine?"
"Okay. Hold on. Even if I did agree for you to kill me and fax me in JPEGs to another universe, how would my doppelganger even get back? Is there a laser on the other side that's going to kill him, too?"
"Don't be stupid. He'll have this little wafer that he can click and instantly return back here, unharmed, whenever he feels like it. Okay, hold still and try not to piss your pants. Your doppelganger is going to be wearing those in a few minutes."