Sometimes all it takes is the right question at the right time to unlock your mind and direct your thoughts down paths lush and generative. Share what inspires you, and I will show why I have been called insatiably curious.
OK, dinner table argument from my past - I just thought of it recently watching a Doctor Who episode. I argued that time travel is not possible and never will be possible at any point in humanity's timeline. My argument was human nature - If this kind of ability were to be developed, there is no way it could remain "controlled knowledge" (a secret?) forever. And once it "got out" people would misuse the technology to travel back in time in an attempt to secure a fortune for themselves. That or get laid.
So, the fact that there have not even really been many National Enquirer or Sunday Sport type stories about time traveling futurepeople is all the proof we need that time travel is realistically (if not theoretically) impossible.
Any thoughts? Support for my hypothesis? Sounds crazy, but I am dead serious here, people.
Hi Cary! A few immediate, rash, and ill considered remarks to begin with...
It's a splendid question, though if there's going to be a final word on the hoary conundrum of time travel it certainly won't be coming from yours truly. Instead, what I thought I might do here is to reconstruct your argument formally for ease of appraisal.
Insofar as you weren't explicit about what form your argument takes, it seems to me a formal reconstruction could be done in more than one way. For example, you might present your argument as an "Inference to the Best Explanation" (i.e., the best explanation for the fact that history records no instances of time travel abuse is that time travel is impossible).
Here, though, let's see how it might look in deductive form:
Premise 1 : If time travel were possible, history would record instances of time travel misuse (of the "wham, bam, thank you Cleopatra, now where's the gold?" variety)
Premise 2 : History records no such instances of time travel abuse
Conclusion (by modus tollens) : Time travel is impossible
Reconstructed this way your argument is deductively valid: In other words, true premises guarantee the truth of the conclusion. The soundness (i.e., truth of the premises) of the argument, on the other hand, is quite another matter. Both premises, it seems to me, are susceptible to challenge; the first more obviously than the second.
Premise 1 might be challenged, for example, by claiming that humanity would have to first attain a certain threshold of technological advancement before time travel became accessible to amorous English lager louts eager to scoot off in their Safeway Personal Time Machine for a Nile-side assignation with Cleopatra. And that threshold (apparently) has not yet been transcended.
Wait till you read the history books of the 25th century! Other members may fill in the gory details.
Any thoughts, Cary? What form do you yourself see your argument as taking? And thanks for a thought provoking morning. Must fly now. I have a date with Helen of Troy...
Now you ask me what form I see my argument taking and I am all like "hunh?" (I know how much you like the extraneous likes). You know street fighting vs. fencing? That's me. Street arguing. Don't forget I am not the one who became a lawyer. I remained an uneducated smartass. So I dunno about this "form" of which you speak.
What I wonder about is if your fancifying up of my argument took into account that we don't have to "wait till you read the history books of the 25th century". IF time travel were possible, and IF humans were still human (according to my theory), wouldn't there be a chance we would have seen someone from the 25th century already, maybe at last year's Super Bowl placing an enormous bet at halftime that the New England Patriots would win the game? ( Super Bowl LI Go ahead Colin, click it).
I suppose the other premise that must be considered is that all time exists at once - we are just passing through. Alas, the existence of time travel would be a great help in proving this theory.
Thanks for indulging in my humorous, yet earnest discussion. If nothing else, it does serve as a nice platform upon which you can enlighten me as to the various forms of argument.
Cary (CaryTyson) said:
What I wonder about is if your fancifying up of my argument took into account that we don't have to "wait till you read the history books of the 25th century". IF time travel were possible, and IF humans were still human (according to my theory), wouldn't there be a chance we would have seen someone from the 25th century already, maybe at last year's Super Bowl placing an enormous bet at halftime that the New England Patriots would win the game?
Yes, there would be a chance. But that was the point of the possible objection that I suggested might be levelled against Premise 1: that the 25th century (or whenever the threshold is) hasn't arrived yet. Therefore, the reason we don't see suspicious Super Bowl scoops is not that time travel is impossible, but rather, time travel is not yet feasible.
The paradoxes of time travel are well known, and there are good a priori reasons (i.e., no science necessary) for thinking the whole concept may be incoherent. After all, as you note yourself, it's difficult, perhaps impossible, to imagine a universe in which time travel occurs without the thought experiment collapsing in on its own absurdity.
But let's bind our intuitions for now and assume that ours is indeed a universe in which time travel is possible. We can still agree, surely, that a certain period of development would be necessary before organisms within this universe begin availing themselves of time travel technology (no stegosaurs at the Super Bowl). An opponent of yours, Cary, could simply argue that time travel is perfectly possible, but it's just that the time isn't ripe yet.
It seems to me, in street fighter mode LOL, that your evidence (no documented instances) provides fairly strong evidence to support a conclusion that no human has ever engaged in time travel. But your claim is much stronger than this: not only has time travel never happened; it cannot happen.
This conclusion (time travel, as described by yourself, is impossible) seems to me eminently plausible. The particular evidence that you adduce to support it, though, (no recorded instances) strikes me as weak. Isn't this a bit like arguing, circa 1900 perhaps, space travel (or nukes or whatever) has never been achieved, therefore space travel is impossible?
The 1900 "space travel has never been achieved, therefore is impossible" argument is like comparing apples to oranges. I am talking TIME, here - and that has made all the difference. The premise of time existing all at once is probably the piece upon which my argument rests most firmly. So time is not a matter of where you or I are on that particular spectrum, but there exists at this moment all of time. I mean, if time travel was possible, would we be able to travel both ahead in time as well as behind? Only if "ahead" already exists, right?
I never claimed to be good at this argument stuff, just a fan of it.
Re: time travel
The Earth is not the static center of the universe. To go back to yesterday you would have to move to where the Earth was yesterday and have the Earth be there again. Tomorrow events have not happened yet so we can't visit tomorrow. The events of tomorrow depends on the events of today and the actions of all the people in the world. This as well as the problem of moving the Earth ahead one day in its orbit pretty much makes time travel impossible.
NICE!!!!! Great thoughts.
While my original post was slightly tongue in cheek, the concept of time travel is one that fascinates the human imagination. My first introduction to it was in college studying Richard Feynman (in a physics for non-science majors, so I still know nothing about it) and some of his theories of antimatter and whether matter can move backwards in time. That course hooked me with its excitable, "what if" approach to our physical world.
So while I have learned tiny bits about the tachyonic antitelephone and a closed timelike curve, It has served only to pique my interest, and has most likely really confused me further, although I am ignorantly, blissfully, unaware of being so confuddled. Ain't life grand?
Thanks for jumping in!!!
It is great mind candy, isn't it. But just doesn't fit reality ... as far as we know today.