Hypothetical scenario. At the end of last semester, I got okay grades in my courses. Not great, but passable. Let's say that today I somehow come across a time machine; I'm not able or willing to help my past self cheat outright (test questions, homework solutions, etc.), but I can give him a little motivation; I go back in time to last August and tell him that if he doesn't get his act together, he will screw up bad and lose out on a job offer.

Of course, my past self has thought of this very same issue before. He is, after all, a savvy Worldbuilding reader. I am quickly able to convince past me that yes, I am indeed him six months into the future. But, here's the problem; past me is just as much a skeptic as present me is. How does he know that I didn't come back in time to lie to him? How will I know that past me will walk away and ultimately do nothing (or worse, get lazier) because he thinks I'm exaggerating or stretching the truth a bit?

So, my question is ultimately this: How could I go back in time to the recent past (under a year) and convince past me of some lie? Also, how could past me determine that present me is lying or exaggerating?


closed as off-topic by bilbo_pingouin, HDE 226868, Jim2B, Brythan, type_outcast Jan 25 '16 at 3:38

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about worldbuilding, within the scope defined in the help center." – bilbo_pingouin, HDE 226868, Brythan, type_outcast
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    $\begingroup$ Hi Jesse, welcome to Worldbuilding. As much as I wish I could go back to give some hints to my past self, that question isn't about Worldbuilding, but it is about the actions of a single individual. And as such, I think it is off-topic. You can read more about it on the tour or on-topic. $\endgroup$ – bilbo_pingouin Jan 24 '16 at 22:17
  • $\begingroup$ If future me found a time machine and the only thing he could think to do with it is come back and hassle me about my grades, I'd take that pretty seriously. $\endgroup$ – sh1 Jan 24 '16 at 23:13
  • $\begingroup$ 'Let's go get two do-dos and force them to make out!' $\endgroup$ – Xandar The Zenon Jan 25 '16 at 1:23

The answer to this question lies in another question, "Under what conditions would a future version of a person give bad advice to their younger self?"

I don't think it matters if the future you is lying or not. The issue is not absoulute truthfullness. This is an issue of insight and intent. If the future you is actually from the future that you are currently heading towards, then their insight (i.e. their understanding of the consequences of your current life) will be greater than your own. Which leaves the question of their intent.

Are you a self-hating masocist who upon finding some happiness later in life, might travel back in time to steer younger you away from it?

If not, don't worry about whether future you is lying. Accept whatever they tell you as gospel and get to work!

---one more thought---

Don't assume that future you has the same goals as you do. Imagine that instead of studying tonight, you go to the corner store and buy a lottery ticket and that a few days later, you are a millionaire. Future you may already have learned the hard way, that you are not qualified to drive a ferrari at top speed. Future you might also know that the love of your life, whom you are currently dating, has an aversion to wearing safety belts. Future you's suggestions may have nothing to do with fixing your grades or getting some fictional future job. They may just want to keep you way from that corner store and by extension out of some non-fictional wrecked and blood covered ferrari.

  • 1
    $\begingroup$ When I have a time machine I will go back in time to screw with my past self to vent my anger for that guy from the future who destroyed my life with bad advise when I was younger. $\endgroup$ – Philipp Jan 24 '16 at 22:11
  • $\begingroup$ II'm going to go forward in time, come back with some futuristic technology, and sell it. Humanity, and my pocketbook, are all felling like they got a bargain. $\endgroup$ – Xandar The Zenon Jan 25 '16 at 1:28
  • 1
    $\begingroup$ Future you might be suicidal. $\endgroup$ – Howard Miller Jan 25 '16 at 3:03
  • $\begingroup$ @HowardMiller, I almost covered that contingency in my answer, mentioning suicidal tendencies when I was asking about masocism. Now I know I was wrong to not include it in my answer. Thanks for adding it here! $\endgroup$ – Henry Taylor Jan 25 '16 at 3:21

Use make-up to make yourself look much older (but still recognizable). Then tell your past self that you are not just from 6 month from the future but actually 10 or 20 years.

This gives you far more authority, because your past self will assume:

  • That you have turned much wiser over the years
  • That you can judge the impact of current decisions much better because you don't just know the immediate consequences, but the consequences they will have years from now on. Saying "you will lose a job 6 months from now" doesn't have nearly as much impact as "you won't find any decent job for the next 10 years".
  • That you've changed over the years, so his/her knowledge about himself/herself won't apply to you anymore

Not the answer you're looking for? Browse other questions tagged or ask your own question.