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How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 4:12 am UTC
by Lem0n
You met someone who claims to be your "future you". What do you ask him to confirm it?

Rules:

1) He claims he's you 1 year in the future (he may have learn or forgotten things in this period);
2) He WANTS to prove he's your future you (so he won't answer something he knows incorrectly in order to confuse you);
3) If he's fake, he may have got information about you with your friends, family, hacked into your computer, sniffed your network, etc.

Let's see the most creative ways.

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 4:14 am UTC
by Lem0n
My takes:

1) A logic test
as long as my "future me" hasn't have some kind of brain damage in this 1 year, he should do as good or better (but hardly way better) than me

2) A pattern finding test
same as above

3) A question that has a less than 1% chance to be guessed, just I know and that I didn't share with anyone nor put on my computer.
(Couldn't think of any)

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 4:22 am UTC
by poxic
"What's our worst habit, as you thought it was a year ago?"

"Who is our favourite family member, as you thought of it a year ago?"

"What pieces of clothing [or other items in the home] do we hang onto despite hating them muchly, out of some weird sense of duty?"

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 4:27 am UTC
by ++$_
Think of a piece of music (or any similarly memorable item, such as a poem). Ask him what piece of music you're thinking of. Since you know you might to need to produce it a year from now, you should have no trouble remembering. No amount of hacking is going to help an impostor guess this.

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 5:32 am UTC
by bane2571
Everyone keeps secrets deep inside, even if it's something as simple as "who did I have a crush on when I was 8", everyone has at least one thing they have never actually articulated that would be incontrovertible proof that someone knows everything you do.

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 5:43 am UTC
by Lem0n
bane2571 wrote:Everyone keeps secrets deep inside, even if it's something as simple as "who did I have a crush on when I was 8", everyone has at least one thing they have never actually articulated that would be incontrovertible proof that someone knows everything you do.


you need to be careful with the probability of someone guessing that knowing everything that's public
for instance, a yes/no question would be terrible
for your question, he could know all the girls that you studied with near this age and just pick one... considering there should be about 40 girls, that's at least 2.5% chance of guessing

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 6:24 am UTC
by Argency
I would turn on the recording funtion on my phone and say, "I'm about to say a random string of numbers, say them along with me."

Then I'd blurt out 24312324165413100016398795198772 or whatever, and make sure I recorded it. If he said the same number as me, at the same time, every time, I'd know he was me. Then I'd listen to the recording once a day, and recite along with it so I'd memorise it. That way, in a few years time when my past self wanted proof I was him, I'd be able to recite along with him number for number.

Spoiler:
Interestingly, I'd have to memorise the recording even if he wasn't able to recite along with me, because otherwise it could be the case that he was me from the future, but couldn't remember what I was about to say.
Spoiler:
I'd probably say around 100 numbers. That way, the odds of him guessing correctly without any prescience would be completely negligible.

Everybody should have a plan for this situation, because if it ever happens to you and you can prove he's you from the future, then you know you almost certainly won't die until you're at least as old as him. Think of the things you could do if you knew you couldn't be killed! Although, that said, you couldn't put yourself in a situation where your survival was less likely than the government creating an android version of you with your memories and sending it back in time to trick you into thinking you were unkillable...

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 6:37 am UTC
by Lem0n
yes, but it only works if you know your "future you" will visit you
people normally don't do this kind of stuff

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 6:42 am UTC
by Argency
Lem0n wrote:yes, but it only works if you know your "future you" will visit you
people normally don't do this kind of stuff


You mean the "knowing you can't be killed" bit, right? Oh yeah, its a long shot. But just think how AWESOME it would be! Pascal's Wager and all that. You need a zombie outbreak plan, too, if you don't already have one.

If you meant the proof of his identity, well of course it wouldn't work if he never visited me, but if he didn't visit me I wouldn't need it to work. And all the hard work of memorising happens once I already know he is (I am) going to visit. So no effort wasted there.

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 6:44 am UTC
by Gopher of Pern
Well, my future me would already have met me in his past, so as long as he is saying the exact same thing i am at the same time, i would be convinced it was me.

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 4:12 pm UTC
by a_fuzzyduck
++$_ wrote:Think of a piece of music (or any similarly memorable item, such as a poem). Ask him what piece of music you're thinking of. Since you know you might to need to produce it a year from now, you should have no trouble remembering. No amount of hacking is going to help an impostor guess this.


SIXTY NINE DUDES!

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 4:19 pm UTC
by WarDaft
First, ask them if they remember being contacted by future you themselves when they were present you. If yes, ask them to write down what you're going to say next - have them write it down before you've even decided what to say, out of your sight.

Then say anything at random.


If no, then they cannot prove they are future you, because they could in fact just be a similar quantum-you.

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 4:33 pm UTC
by redrogue
This seems particularly trivial. The year gap would make things particularly easy. Ask anything that is very important to you that you haven't shared with anybody else. In my case, "What tattoo were you thinking about getting a year ago?"

I'm more preferential to "how do you determine if you are a clone?"
http://www.smbc-comics.com/index.php?db=comics&id=1879

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 6:15 pm UTC
by Turtlewing
"What number am I thinking of?"

Since meeting my future self is kinda' a big deal I expect i would remember the number I used to conferm my identity.

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 7:12 pm UTC
by Lem0n
yes, that makes sense
I wasn't counting on the possibility that the clone would remember meeting you (it would create recursive meetings, probably ending the universe :P)

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 7:57 pm UTC
by Lounge
Can you tell me how to travel a year backwards in time?

Re: How to confirm if someone is your "future you"?

Posted: Fri May 28, 2010 9:30 pm UTC
by redrogue
Lounge wrote:Can you tell me how to travel a year backwards in time?


I believe you just crawl into a special garage-built box and wait to go back a day, bringing the machine with you. Repeat 365.25 times.

http://www.primermovie.com/ (highly recommended rental, if you haven't seen it)

Re: How to confirm if someone is your "future you"?

Posted: Sat May 29, 2010 1:42 pm UTC
by ConMan
I'd ask a question for which I expect a non sequitur answer, on the assumption that even if someone was weird enough to spy on me to work out the answer to questions about my secrets and/or work out what number I'm probably thinking of, all to pose as a future version of myself, then they would still be unlikely to know *what* question I was actually expecting the answer for.

Re: How to confirm if someone is your "future you"?

Posted: Sat May 29, 2010 9:46 pm UTC
by Lopsidation
The "Think of a random number on the spot" approaches only work with a stable-loop-type version of time travel. If you split into another copy of the universe when you go back in time, you'll be stuck.

My method is, I have a password usable for any of these sorts of situations. I've never said it aloud, it's essentially impossible to brute-force, and it's valid back to when I was 11.

Re: How to confirm if someone is your "future you"?

Posted: Sat May 29, 2010 10:05 pm UTC
by whaatt
"Did you meet me a year ago, claiming to be me?"

Although this might mess up somehow in all of the recursiveness going on.

Re: How to confirm if someone is your "future you"?

Posted: Sat May 29, 2010 11:59 pm UTC
by a_fuzzyduck
Lopsidation wrote:The "Think of a random number on the spot" approaches only work with a stable-loop-type version of time travel. If you split into another copy of the universe when you go back in time, you'll be stuck.

My method is, I have a password usable for any of these sorts of situations. I've never said it aloud, it's essentially impossible to brute-force, and it's valid back to when I was 11.


Also, if an impostor knows about Bill and/or Ted, they'll be able to work that out :D

Re: How to confirm if someone is your "future you"?

Posted: Sun May 30, 2010 1:58 am UTC
by Tirian
I'm reminded of King Nebuchadnezzar who challenged his wise men to interpret his troubling dreams and then sentenced to execution anyone who said "Okay, so what was your dream?"

I'd tell future-me that he has a unique perspective into what it would take to convince me of his identity, and indeed he could not possibly have thought about the challenge less than I have. So I would lean back and expect a demonstration that would satisfy my skepticism without any nonsense that wouldn't interest me. I don't know what future-me would do, but I don't think it's unreasonable to expect that he would be able to rise to that challenge.

Re: How to confirm if someone is your "future you"?

Posted: Sun May 30, 2010 4:10 am UTC
by undecim
I am going to assume a few things:

1: Like a turing test, one's only communication with this person is text-based (i.e. over the internet) This is only for the sake of argument about being identified based on physical traits, or how much they can remember, since in this scenario, they could have access to a prepared database of information about you without your knowledge.

2: This person does not remember the incident as it would have happened to him one year ago, whether by some meta-physical law regarding time travel, or by memory loss.

3: And just to make it interesting, let's assume that there is technology available that would allow someone to read another's thoughts and memory, but not the thoughts and memory of the present you (** equips tin foil hat **)

The common answer would be "ask a question that you would never enter into a computer and would never tell another person, but assumption #3 causes obvious problems with this.

What we need is a question or request that only your future self can answer, but that you yourself cannot answer, but can verify.

Unfortunately, I can't think of such a question.

Re: How to confirm if someone is your "future you"?

Posted: Sun May 30, 2010 4:30 am UTC
by Lem0n
undecim wrote:(...)The common answer would be "ask a question that you would never enter into a computer and would never tell another person, but assumption #3 causes obvious problems with this.

What we need is a question or request that only your future self can answer, but that you yourself cannot answer, but can verify.

Unfortunately, I can't think of such a question.


I think something on the line previously suggested like "What tattoo were you thinking about getting a year ago?" would do it.
You can ask something that you thought of doing, but gave up and didn't tell anyone.
For instance "what's the first name I thought on calling my company?" (but didn't)

but I guess those kind of questions are pretty rare (and some of them, like the tattoo one, usually wouldn't help so much... your "clone" could answer the most likely tattoo a person like you (remember, he may have "studied" you) would get and have something like 5% chance of guessing)

Re: How to confirm if someone is your "future you"?

Posted: Sun May 30, 2010 11:36 pm UTC
by Vieto
obviously ask them what your xkcd password is :P

Re: How to confirm if someone is your "future you"?

Posted: Mon May 31, 2010 6:33 am UTC
by Ddanndt
Ok a really crazy answer to a crazy question ... I start stabbing myself... if the dude's doesnt get any new scars it means he's not me :twisted:

Re: How to confirm if someone is your "future you"?

Posted: Mon May 31, 2010 6:46 am UTC
by Lem0n
Ddanndt wrote:Ok a really crazy answer to a crazy question ... I start stabbing myself... if the dude's ok( doesnt get any scars) it means he's not me :twisted:


damn, that breaks everything
even if he has scars, you can always cut him somewhere where he doesn't

Re: How to confirm if someone is your "future you"?

Posted: Mon May 31, 2010 6:48 am UTC
by Nayto
Ask a question unrelated to the correct answer.

Question: Whats our favorite Colour?
Answer: Cake

The question becomes irrelevent but an imposter wont know that.

Re: How to confirm if someone is your "future you"?

Posted: Mon May 31, 2010 7:48 am UTC
by weex
The problem I'm having right now with many answers is: what if I'm tortured for one or more questions between now and when the supposed me comes back to meet me? I would probably do DNA and fingerprint testing because I do not trust the mind to be the iron vault many previous responses assume.

There is the possibility that this someone is a genetic clone but at that point, I'd just have to hang out with them for a while to see just how deep their knowledge of myself goes. It would probably be closer to an adaptive test than a simple set of questions. Perhaps I could question them on a few spontaneous and unrelated lines of thought with as many questions for each line of thought to satisfy me.

Re: How to confirm if someone is your "future you"?

Posted: Mon May 31, 2010 11:45 am UTC
by Vieto
Lem0n wrote:
Ddanndt wrote:Ok a really crazy answer to a crazy question ... I start stabbing myself... if the dude's ok( doesnt get any scars) it means he's not me :twisted:


damn, that breaks everything
even if he has scars, you can always cut him somewhere where he doesn't


Or, just cut yourself under your shirt, and ask him to show you the wound.

That would work.

Re: How to confirm if someone is your "future you"?

Posted: Mon May 31, 2010 7:28 pm UTC
by a1s
°The "Think of a random number on the spot" approaches only work with a stable-loop-type version of time travel. If you split into another copy of the universe when you go back in time, you'll be stuck.


The way I see it, it's either a single time-line time travel (past can be affected, but always stays the same), in which case you can just make an ad hoc method for time traveler identification (you, as in the present you- for future you it's standard operating procedure, after the first time... though this method does not scale well (you know, for that 3rd you from 2 years into the future). at all.), or it isn't, in which case the whole thing is moot anyway (for example, your future you got lucky and this afternoon just happens to be when will have broken your leg (not known by anyone, but easily verifiable!), so she tells you as much, but then knowing this, you are extra careful and avoid all accidents. Unless you can be sure you are the only time traveler, any other things true for the future you might also be false for the "real" you)

Re: How to confirm if someone is your "future you"?

Posted: Tue Jun 01, 2010 1:20 pm UTC
by Xami
If he didn't bring me a list of the biggest sports upsets with the best odds for the next year, I'd be fairly upset with myself and refuse to listen to myself anymore. I would hope he would have a list of lots of other things that happened that year, and if his presence disturbed the universe enough to change the outcome of a variety of events, we would have to slow our roll.

Also, we would probably part ways at that point. We would either have to pretend to be twins I guess, or not see each other. This is also related to the fact that I like myself, but I can't see me hanging around me. I would be understanding of my request for this :D

Re: How to confirm if someone is your "future you"?

Posted: Wed Jun 02, 2010 12:49 pm UTC
by Trebla
undecim wrote:What we need is a question or request that only your future self can answer, but that you yourself cannot answer, but can verify.

Unfortunately, I can't think of such a question.


Based on rule #2, I'll assume that we aren't in a single continuum, but that going back in time essentially splits the universe.

You would have to ask a question about a future event that you would definitely learn AND you're certain you would remember a year later. "What's your favorite sports team's season record this coming season?" would be an example that would work for some people, but it's not verifiable for some time, and even if he gets it, a well-researched guess would give him a decent chance of successfully impersonating a time-traveler.

Re: How to confirm if someone is your "future you"?

Posted: Wed Jun 02, 2010 4:41 pm UTC
by T-Form
I ask her for a dance, and she has to lead. If she's me, she should be capable of leading most of the moves that I can lead today, and she'll probably still favour a fairly similar set of moves to the ones I currently use most often. She'll also know the names I give to moves that I don't know the real names for, which moves were my favourites at one time or another (and where I first learned them, who first taught them to me, and what else was taught in the same class), and which moves I dislike (or used to dislike) and why. Between the dance and the questions, I reckon it'd be pretty tough to impersonate me to myself.

Re: How to confirm if someone is your "future you"?

Posted: Wed Jun 02, 2010 8:10 pm UTC
by freddyfish
ask to examine your future self's arm. find a place where there is no scar and cut yourself in that place. re-examine his arm for the spontaneous formation of a scar. if it happens, he is the future you.

Re: How to confirm if someone is your "future you"?

Posted: Wed Jun 02, 2010 9:17 pm UTC
by BurningLed
Simple.

"Show me your favorite mole."

If he shows me the same one I have (which I'm certain won't go away anytime soon) then he wins.

Re: How to confirm if someone is your "future you"?

Posted: Fri Jun 04, 2010 7:35 am UTC
by Vesuvius
I have a sequence of passwords prepared. I hope not to get tortured.

Interestingly, I have a similar (in idea, not the words) set of passwords with my friends to be used in an emergency. E.g., they ring me up at midnight and say "(The words), give me a thousand dollars."

Re: How to confirm if someone is your "future you"?

Posted: Fri Jun 04, 2010 6:02 pm UTC
by Qaanol
What are the possibilities?

1. Mystery person is me from the future.
2. Mystery person is someone else from the future.
3. Mystery person is someone else from the present or past.
4. Mystery person is me from the present or past.

We can easily take care of #3 and #4 by asking about something that has not happened (ask them to write down answers to specific questions about tomorrow, and don’t look at them until tomorrow night).

So we need to distinguish between #1 and #2. The ‘spontaneous scarring’ cannot work. If you cut yourself somewhere he does not already have a scar, then clearly this sequence of events did not happen to him a year ago, or he would already have the scar from having cut himself. Therefore the timelines are disjoint from the get-go, and nothing you do ought to affect him.

On the other hand, if you cut yourself “at random” and then ask him to show you a scar that he already had in that location, an imposter-from-the-future could have found the real future-you, located all scars, and inflicted similar wounds on himself. This of course being after brain-scanning or otherwise learning from the real future-you exactly what proof-techniques you will demand (already did demand).

At that point, it rings of the Chinese Room.

Re: How to confirm if someone is your "future you"?

Posted: Fri Jun 04, 2010 8:49 pm UTC
by redrogue
I hadn't considered the possibility of a time traveling impostor. DNA test, maybe? Though, GATTACA brings this to question. DNA test plus rigorous medical examination to examine for any cosmetic surgeries performed, perhaps. Though, if there is time travel technology, plastic surgery might have reached terrifying new levels of perfection.

Perhaps some future mad scientist built a clone of me, tortured/extracted every possible fact out of a future me, trained said clone well, applied known external and internal injuries at the appropriate junctures in that clone's life, and sent him back in time.

I've been wracking my brain trying to think of a sure-fire method for identification. Fight to the death (if you lose, he's lying). Random gun firing machine (your future you reveals a bullet scar, then pushes the button to shoot you in a random place). Tattoo gun that prints a GUID. Carbon dating.

This question is now less logic and more philosophy. The only way to know for sure is to wait a year. I'd just take his word for it in the mean time.



Edit:
Take future you to a medical professional. Have doctor confirm a bullet wound on the time traveler is 11 months old. Lock yourself in isolation. Cut off outside communication. Faraday cage. Etc. Bring medical supplies. Build random gun firing machine. Analogue, of course. Wait a month. Get shot in a random location. Treat wound. Wait another month. Remove self from isolation.

If received your random wound in the same location as your future you, and you know it was received at a location that could only possibly be known by yourself, with a one-month window on either side to allow for variance in bullet wound dating error, then it's a future you.

Re: How to confirm if someone is your "future you"?

Posted: Fri Jun 04, 2010 11:45 pm UTC
by ++$_
Lopsidation wrote:The "Think of a random number on the spot" approaches only work with a stable-loop-type version of time travel. If you split into another copy of the universe when you go back in time, you'll be stuck.
But if the person speaking to you isn't from YOUR universe's future, it's not really a "future you." It's a future someone else. In my opinion, it's questionable whether moving to another universe even counts as time travel at all.