The ol' Grandfather Clause

I read your column in the archives on whether time travel was possible, and you mentioned the Grandfather Clause, where if you go back in time and kill your Grandfather, it would become impossible for you to have been born, and so you couldn’t have killed your grandfather, which is a big fat paradox. So what’s the deal? If you went back in time and killed Grandpa, would the universe just alter itself to fit your actions, or would you get booted to a parallel universe where the consequences of your dirty deed play out, or would something even freakier happen?

I went back in time, and talked a Texan millionaire into marrying my Mom, so I could be rich instead of who I am now, but as you can see, I got booted to this parallel Universe, and I’m still the same old me!!!

C’mon! You can’t ask this kind of question, or at least you cannot structure it that way.

Nobody knows the answer, or does someone in here knows? What year is it now? Cleopatra, hun, are you there?

Men will cease to commit atrocities only when they cease to believe absurdities.

The part about going back in time and killing your grandfather is no problem logically; all you’ve got to do is invent the technology. The reason it appears to be a paradox is that everybody assumes that the present we’re BSing in, right now, is ‘the’ future, from the point of view of your grandfather’s day.

Truth be told, we don’t even know what time is, exactly (having recently taken on the definitions of life and consciousness with his usual excellent style, Cecil should try to tell us what time is, next).

The problem is, you’ve got all of these electrons bouncing around in probabilistic fashion. If the dice God uses to run the Universe bounce one way, the electron goes one way, and we’re on the road to one future. If the dice come down another way, so does the electron, and we’re headed to a slightly different future. If you go back to your grandfather’s time and sit in a cave for fifty years, the present you come out to after all that time won’t be this one.

So if you go back to a moment before your parents were conceived and, five minutes later, kill your grandpa, you’re killing him in a different future (of the moment you went back in time to) than the one you were born in. Your birth happened in one branching from that moment; you’re in another. You can’t be born in this branching, but that’s no prob; you arrived fully grown in this one. You were born in the other one, and being born once is all you need. That may seem kind of strange, but hey, you’ve got to expect weird things to happen when you go back in time.

What you can’t do is travel to the future, because there is no ‘the’ future. But you can travel to a future, though it’s likely to be at the same one-minute-per-minute rate of travel that the rest of us manage. But at least the technology’s already there.

Sam Craft wrote:

Isn’t this the Grandfather Paradox? The Grandfather Clause, IIRC, was that sneaky and racist proviso in postbellum literacy laws that said, even though you are too ignorant to find your butt with both hands and a map, nevertheless, if your grandfather was a voter, so are you? By extension, any clause that permits an existing situation to continue without penalty, although it is prohibited ab initio.

“Gold cannot always get you good soldiers, but good soldiers can always get you gold”

Of course it’s the Grandfather Paradox, not the Grandfather Clause. Picky, picky. Thanks for making me learn a new Latin legal term, tho.

I forgot who it was, someone famous who approached the Grandfather Paradox by asking, how could anyone know for sure who his/her grandfather was?

Akatsukami - I think you mean “prohibited henceforth”, not “ab initio.” If it was prohibited right from the beginning, then no-one would ever have had the legal right to do whatever it is, and therefore no need for a grandfather clause.