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### How do you define..."you"?: Question about Infinite Universe

Posted: Thu Nov 23, 2017 7:21 am UTC
Just watch something about infinite universe thing, and that make me question: Infinite universe mean infinite self, as it's known right?...But how could you even make a distinction that would make a certain person "you" in an alternate universe/timeline? For instance, let supposed you treat that person Demon You, but in order for that to happen, vastly different set of circumstand is needed to happen. Heck, let not even talk that far.

What if the person is completely different, but have your name and have your fate, as you have been switched at birth.

What if the person is the same, genetically, but it's due to some widly different set of gene combination coming from different family pairing that just happen to create this version?

What if there're a universe where all of the people there are "you"?

Can you distinct it, up to a certain point, or is it the notion of alternate self is absurb in the first place, and there's no way to certainly define?

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Nov 24, 2017 12:10 am UTC
andykhang wrote: Infinite universe mean infinite self, as it's known right?

I don't follow this logic at all and suspect that this is a major issue with your overall thinking. Could you explain what you mean more by "self" and how you think this follows?

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Nov 24, 2017 9:37 am UTC
The alternate self idea? That's there is infinite version of you when you have infinite universe?

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Nov 24, 2017 9:55 am UTC
andykhang wrote:The alternate self idea? That's there is infinite version of you when you have infinite universe?

Are you talking about a multiverse (i.e. parallel universes) rather than a single infinitely large universe?

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Nov 24, 2017 12:30 pm UTC
What I think he means:
Infinite universe = infinite planets = infinite earths = infinite earths EXACTLY like ours...

Or an infinite number of planets were Justin Beaber was killed and we genetically engineered those really cute penguin things from star wars into being.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Nov 24, 2017 3:18 pm UTC
AFAIK even an infinite universe is supposed to spawn infinite copies of you, me and everything, assuming the laws of physics are constant, and the starting configuration of the universe is roughly uniform. This follows from a probabilistic argument: you're the outcome of a random experiment with P(you exist) > 0 (as observed), thus an infinite number of experiments will yield an infinite amount of events of you happening.

This is one of many cases where our habit of categorizing classical-scale objects shows its shortcomings. We say that this thing is a dog, that thing is you, and the thing over there is a ship. All of these words are useful concepts that we use to talk about things in a meaningful way, and using these concepts makes communication about everyday experiences a lot easier.

None of these concepts is strict and unambiguous, because there's no physical truth to a concept. Even something as simple as "this is the same ship" is impossible to rigorously define without stumbling over some corner cases, and it's also impossible to define what is "you" without inevitable stumbling across the corner case of someone very similar to you, but distinct (or causally disconnected) from you.

So how would you define "you" in an infinite universe? However you want, as long as it remains a useful word in conversation. Personally, I wouldn't even try to categorize people from other planets into "you" and "not you", no matter the similarities, because I fail to see any insightful statements to be derived from that. Conversely, any insightful statement would need to be more precise than simply calling both people "you".

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Nov 24, 2017 5:12 pm UTC
jaap wrote:
andykhang wrote:The alternate self idea? That's there is infinite version of you when you have infinite universe?

Are you talking about a multiverse (i.e. parallel universes) rather than a single infinitely large universe?

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Nov 24, 2017 5:40 pm UTC
Like Tub said, you can't even define yourself in this universe, so it shouldn't be surprising that you can't define yourself in others either.

Go get a haircut and you'll be a different person. Grow through puberty, lose an arm, get a brain injury, replace your hip with titanium, whatever the case may be - you are not the same person as when you were born, philosophically speaking. The idea of "self" is meaningful to humans, but not to the universe.

If you want to expand that to the multiverse to include a category of beings that are perfectly identical to you (down to the same haircut), you can do that, and it will include infinite beings... but the only one who thinks that means something is you (and maybe some other humans). The universe still doesn't care.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sat Nov 25, 2017 1:15 am UTC
You need something that only a real, veritable you would know. I designate a special handshake, that should I ever meet a putative copy of myself, I know they are actually another self if they know the handshake. There are infinitely many universes that contain another such self, one who knows the handshake, so we could make a pretty good club and be pretty satisfied. There are also infinitely many universes that contain someone who might resemble me in all other aspects *except* the handshake, but fuck em.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sat Nov 25, 2017 11:23 am UTC
It wouldn't matter much if there are Infinite Yous, as you'd never meet.

Distributed as you are around the Infinite Volume, the True Yous that are exact copies will be product of identical light-cones, and never so close as to meaningfully share existence. Even if one went and travelled to another 'tile' of You-Home, that You will be travelling to yet another You-Home (because they are You, and You are doing this, otherwise you wouldn't be You) and another You will get to your You-Home only after your You has left.

(The alternative is to have.something like the situation of rotationally-orientated versions meeting at a nexus betwixt Yourselves, like that scene with the Other Lara 'enemy' from the first Tomb Raider game, but to extend that to infinity... The tiling (and it would have to be tiling) would have to be of a kind such that edge-on-edge tile boundaries always flip 180°, in 2D, and additional dimensions introduces the possibility of twists, but) which restricts the tile geometry somewhat. And would imply like-on-like meeting of features at the edges of the tiling elements.)

It must therefore be as if your universe is finite but unbounded (wrap-around) with everything repeated across the tile/wrap boundary1. Or else the next You over isn't quite You. And sufficiently so to make the original assumption moot, in the long-term.

1 That's boundary across space. Interesting things likely happen when you allow to displace across time-wrapping boundaries. Effective time-loops (if assumed wrap-around) or a lap circle-like 'inclined time plane' if each encounter of mature Yous (the fundement) is always with neighbouring You neighbours who were younger (the knees), in the same manner as the mature You, when younger (their knees) was met by the other adjacent maturer You (this other's arse), to provide entirely identical experiences for every You even without (with the right time-plane inclination against space-time, and some effort by every You) the necessity of a closed time-like curve.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sat Nov 25, 2017 2:49 pm UTC
Soupspoon wrote:It must therefore be as if your universe is finite but unbounded (wrap-around) with everything repeated across the tile/wrap boundary1. Or else the next You over isn't quite You. And sufficiently so to make the original assumption moot, in the long-term.

I don't think the OP was suggesting that there would be infinite exactly identical copies in predictable tiled locations. Rather, in a statistical sense, in any place you look there is some (vanishingly small) non-zero chance of finding an identical copy of yourself and a similar chance of finding a mostly-identical copy with any given small variation, so that if you look in enough places, then you'll eventually find arbitrarily many arbitrarily-identical copies of yourself. They wouldn't be spaced at regular intervals, and so there's no reason why you couldn't come across one (although as soon as you meet, you're likely to diverge pretty quickly due to having different circumstances after the meeting).

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sat Nov 25, 2017 4:25 pm UTC
Uh...I'm not talking about that, either, but forgive me for ambiguous language. I just mean a realatively simple situation, in which you discover that you're in a multiverse, and each verse have a different kind of You in it.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sat Nov 25, 2017 8:06 pm UTC
i already live in a world with differend kinds of Me. my neighbours are different kind of me. after all they are similar (humans, same street, ...) to me, though not equal.
what's the difference to the other You's you are talking about? that they'd have the same name as you? i'm sure there are some people in this world with the same name as i.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sat Nov 25, 2017 8:30 pm UTC
andykhang wrote:Uh...I'm not talking about that, either, but forgive me for ambiguous language. I just mean a relatively simple situation, in which you discover that you're in a multiverse, and each verse have a different kind of You in it.
That wouldn't happen. Each verse would have a different kind of "almost-you" in it. The question then becomes just how "almost" does it have to be to be an "almost-you". There could even be a verse in which
there are two "almost-you"s; which one of them is the "real" almost-you?

"Almost-you" is defined as much by "almost-identical" past experience as by "present" similarity. This is the same question that comes up when one asks "What if we met three years earlier" or "what if you married Fred instead of John" or "what if you were {black | Christian | gay | older | whatever...}, to which the answer involves just how much else you are allowing to be different as a consequence. Because you can't change things in isolation.

"Almost-you" is also defined a lot by surroundings. If everyone and everything else around "(not-so-)almost-you" is the same, but "not-so-almost-you" is {insert lots of differences here}, then that person is fulfilling the role that "you" fulfill in your own verse. So, this very-different person is arguably "you" in the new verse, even if it is a very different person.
Spoiler:
So, what if there were a universe in which you and your best friend were swapped? You married your best friend's spouse, and has their job, and v.v.? Who's the real "other-you"?

Simple non-philosophical application: you have a program that reads temperature, and want it to do something when the temperature reaches 100 degrees.

while (working)
{ get (temperature)
. if (temperature = 100) {do stuff}
}

This could work if temperature were an int (always a whole number). But temperature is a float; it can be 67.25343, 94.1413, 100.3162, 104.0000001, but it is highly unlikely to actually be 100.000000000000000 (as far as the limits of measurement and digital representation goes). It might even be impossible for the temperature to be listed as exactly 100 degrees because of the way binary converts to decimal. So, you have to write something like:

while (working)
{ get (almost-temperature)
. if ( almost-temperature<100.001 and almost-temperature>99.999) { do stuff}
}

to give it a range to work with.

What your range is (just like what differences between you and almost-you you'll tolerate) depends on why you are asking the question to begin with.

Jose

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sat Nov 25, 2017 11:32 pm UTC
andykhang wrote:Uh...I'm not talking about that, either, but forgive me for ambiguous language. I just mean a realatively simple situation, in which you discover that you're in a multiverse, and each verse have a different kind of You in it.

That doesn't make sense, not even in fiction. Even if we assume that earth and humanity evolved in every single multiverse: In almost all of the other histories, one of your ancestors would have died before reproducing, would have fallen in love with a different person, would have been rejected by their love, would have gotten a boy instead of a girl, would have gotten a single child instead of twins, would have decided against children, or would have any other minor difference that would effectively prevent you from being born.

The premise that there's a parallel universe where the nazis have ruled and massacred the world for a century, but somehow all your protagonists were still born, met each other, and are working together.. that's a tv trope that makes for interesting stories, but it's so wildly implausible that an exact definition of "you" is the least of its problems.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sun Nov 26, 2017 5:34 am UTC
Even if there are an infinite number of Yous, that's across an infinitely more infinite number of worlds, therefore there are, on average, zero Yous anywhere. You, yes you, therefore don't exist. QED.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sun Nov 26, 2017 5:48 am UTC
Tub wrote:In almost all of the other histories, one of your ancestors would have died before reproducing, would have fallen in love with a different person, would have been rejected by their love, would have gotten a boy instead of a girl, would have gotten a single child instead of twins, would have decided against children, or would have any other minor difference that would effectively prevent you from being born.

Well, this is true, but largely because the set of all possible histories is a much larger infinity than the set of all possible histories into which "you" (however we want to define that) would be born - but that set is, while less infinite, still hypothetically infinite-ish, at least for suitably loose definitions of "you."

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sun Nov 26, 2017 1:08 pm UTC
There is only one you, the mind looking out through your eyes.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sun Nov 26, 2017 1:53 pm UTC
morriswalters wrote:There is only one you, the mind looking out through your eyes.

You would say that. All of You.

(Determinism FTW!)

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sun Nov 26, 2017 2:56 pm UTC
andykhang wrote: I just mean a realatively simple situation, in which you discover that you're in a multiverse

do not

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sun Nov 26, 2017 4:18 pm UTC
Soupspoon wrote:
morriswalters wrote:There is only one you, the mind looking out through your eyes.

You would say that. All of You.

(Determinism FTW!)
If you say so, I don't understand determinism, I leave that for others. I have an old fashioned definition of me however.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Fri Dec 08, 2017 9:34 am UTC
@ucim Why?...Just curioucity, I guess? If I have to put a label, I guess I want to indirectly ask the "uniqueness" of certain thing. In what point does something similar deviated itself enough to count as different, assuming the scenario above, act as 2 environment with only one key different.

As for the actual question. I guess just the same "name", same label for the nearly same role in that certain place is...nearly enough? Honestly, at certain point, almost-you and you is completely different anyway.

### Re: How do you define..."you"?: Question about Infinite Universe

Posted: Sun Jan 14, 2018 9:58 pm UTC
Let's say we either live in an infinite universe that either has truly "constant" physical constants but (on the largest scales) uniformly random initial conditions, or perhaps even an infinite universe with uniformly random physical constants and initial conditions. In either case, there should be infinitely many copies of "you," sure, but there are also infinitely many copies of the Earth, complete with all living people on it doing exactly what they are doing now. There are even infinitely many copies of the Laniakea supercluster of galaxies, and so on. We could stretch it to our entire observable universe, and there are still infinitely many copies of that. In such a situation, the copies of "you" will not diverge from each other; by construction, we have included only those whose observable environments are identical to your own, so they will all have identical lives from beginning to end.

Assuming you can call anything else "you," these people would certainly have to qualify.

Your questions then deal with progressively less perfect copies of you. They are still basically the same, but they have increasingly less subtle differences. For instance, you wonder about a person who is genetically identical to you in a universe (or big patch of the universe) that closely resembles yours but actually is different in every other relevant way, including different parents. I think in that case, you would be hard-pressed to say you are the same person. You are, in fact, less similar to this person than you are to your identical twin, since at least you and your identical twin share biological parents. Genetics are a thing, but they aren't everything. In the other example, you and this other person do share parents, but you have different genes. Again, I think it's a stretch to call that person "you." They share some details of your life, but they are genetically different, and as I said, genetics are a thing. Your third scenario asks about "a universe where all of the people there are 'you'." I'm not sure how to deal with that. There can't be such a universe, because as I have already argued, the usual definition of "you" depends on your environment, and your environment includes interacting with all sorts of different people. A person with your genes who is forced to live in a universe full of other people who also have your genes will not lead a similar life to your own and will behave very differently. Again, it will just be a person with your genes, but otherwise much less similar to you than an identical twin.

Do you have any specific questions?