Happy Independence day

I was hoping to spend this day watching Jefferson present the Declaration of Independence, but apparently the mad scientist had other plans. And besides, we may still go there yet! It took him some time to find the cellar this morning, and when he turned the light on, what I saw scared me out my wits; at least a thousand rats squirming around.
"Oh," he looked confused, "Wrong room. This is my Guinea Pig center."

"But they're rats."
"Yes, I know, but golly gee, do you know how much Guinea pigs cost? Rats are much cheaper. They seem to be quite happy here, anyway."

"How'd they all get here?"

"I was testing the time-travel mechanisms with them. After that, I made a few more caches just in case." He walked out of the cellar and wandered around for a while until he found another cellar. I hung behind, afraid of what this one may contain. I was right to be afraid; loads and loads and loads of ammunition of various kinds, and many, many guns to match.

"You'd be even more surprised if you saw all of my evil lair. There are even more weapons in there, but I don't think we'll need more than this."

"Where are we exactly?"

"Oh, some time in the forties. I believe our location is in the deserts of Africa."

"Now," he stood on a chair and spoke to me, as if to an audience."

"So far, Novikov's despicable theory has held up to my tests, which is disappointing. However, if I have a chance to prove it wrong, it is with this." he waved his arm over the ammo cache, "I will see if I can't change the future or die trying! Well, actually, I don't want to die, but I might get close with some of these."

"Excuse me?"

"Hmm?"

"May I speak?"
"Yes, you may."

"This may sound dumb, but what is Novikov's theory?"

"There's no such thing as a dumb question. Novikov's theory simply states that nothing changes."

"But what does that mean to us?"

"Please, no dumb questions." he continued, "Now, we are going to a place where we will be in peril every second. So take this," he twirled a loaded handgun around a few times and almost shot himself twice from his finger hitting the trigger, then he threw me the gun, which I wisely allowed to drop to the ground before picking up, "and these." he threw me a few cartridges of bullets. Remember, there is no such thing as being cautious where we are going. If there is someone about to shoot you, it is you or them. You must shoot first. It is sad, and scary, I know, but it is the truth. And don't worry, if Novikov-may he roll over in his grave-is correct, you won't shoot anybody who isn't already dead anyway. Now take this minute-man uniform." he handed me a raggedy jacket. "Well, here's to not getting shot the moment we materialize." and he took a bite out of a double-cheeseburger he had stuffed in his pocket, and then pressed 'enter'.