The Multiverse and you – Is there another version of you somewhere out there? | Hacker News Reader

The Multiverse and you – Is there another version of you somewhere out there?

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55 pointsmparramon49 comments

So if I get it right, there can't be another you because there are too much particles (and possible interactions between them) in the universe.

Perhaps there isn't a universe where every particle is the same as in ours, but we could be just concerned about the particles our galaxy for example. I might be wrong, but I think it might be theoretically possible to have the same earth in a totally different universe.

What I find somewhat counter intuitive is that, the more particles there are, the less our chances are that another version of us exist, I would have said it makes the chances bigger, or at least in our own universe.

>What I find somewhat counter intuitive is that, the more particles there are, the less our chances are that another version of us exist, I would have said it makes the chances bigger

Think of it like this:

If a human ("Joe") was just one particle, then the chances of the same human being recreated elsewhere would be 100%. As long as that particle is present, there's Joe.

If Joe was made of 100 particles, then the chances are less, because those 100 particles would have to be aligned/interact in the same way, which is much less probable.

Or maybe think of it like this: if you throw a dice, to get 6 is quite easy. You have 1 in 6 chances.

But if you throw 10 dice to get them all six is very very improbable (1/61/61/6*...).

Think of the particles like dice.

Yes, the more particles Joe has, the less it is likely that it will be recreated elsewhere. But here I'm talking about particles not being Joe, the rest of the universe.

I see it this way, it doesn't matter that I get 10 times a 6 when throwing a dice, I just want a 6, I'm not concerned about the whole process, just about the result. Aren't there many ways to get to a point where particles assemble to form a brain similar to our own?

Also, is it possible to ignore the vast majority of the universe, because is a dim light from a star so important, or do we have to, because of the butterfly effect?

An interesting implication of the multiverse theory is that it provides an answer for how we ended up with a universe with just the right combinations of gravity, electromagnetism, strong and weak nuclear forces. It's like the Goldilocks story -- tweak any of them to any other value and all matter would either repel into an nearly empty space or attract into one mass that would collapse under it's own density. There are other reasons for the multiverse theory, but under a theory of infinite multiverses, you would by definition create a universe where all the right combination of forces would come together to form our stars and planets -- including ones that can sustain life.

"it provides an answer for how we ended up with a universe with just the right combinations of gravity, electromagnetism, strong and weak nuclear forces."

No, we just ended up with a universe with the gravity, electromagnetism, nuclear forces that we know. That definitely doesn't make it "right." There could (should?) be an infinite combinations of those that would be "right" in other universes.

Right for sustaining life and that you and I are here and are having this discussion. This isn't a judgement of good or bad (though I'm glad to be here), just accounting for the the odds of arriving at our universe on chance alone. :)

I can't help but think that in 200 years time this sort of meaningless and vapid introspection about the improbability of even existing will have thankfully gone the way of theology.

Said a different way, if you believe in the fine-tuned universe theory, then the multiverse theory would by definition predict our own outcome. It doesn't make either true, rather one of many puzzle pieces that happen to fit together. In 200 years, we may have proof of gravitational waves (or have found none) and many other interesting puzzle pieces that will continue to drive the thinking within quantum mechanics and string theory. Some believe the entire branch of string theory to be philosophy -- though I think this is limited by the belief that because we can't test many of these theories today that we will never find a way to test them in the future.

I've always wondered about something similar: our universe (and our planet) is good for sustaining this specific type of life. But it doesn't mean there won't be any other type of life out there that could have been sustained with something different. Ie. it's possible that any type of universe would have produced life, and when lifeforms from different universes meet, they might not even recognize that it's life

That is a very interesting thought. out very definition of life hinges on the types of life we have seen. So its entirely possible that we may not even recognize other types of life

I also took your right to mean "right for sustaining life," and not as good or bad. However, as NhanH said very eloquently, we are only aware of "our" kind of life. Other lives may be very different, and may not depend on things that our lives do.

This is certainly possible. I should expand my definition as not only sustaining life, but rather avoiding two extremes: one scenario in which all matter repels from all other matter (on an infinite scale) and another in which all matter collapses on itself. These events would seem rather cataclysmic for our universe as a whole, but that could be chalked up to our limited understanding.

You're referring to the Anthropic principle[1] here, I believe? I tend to think this is not a very satisfying explanation, because it is not falsifiable[2]. More compelling/satisfying as an explanation to me, though controversial, is Lee Smolin's theory of cosmological natural selection[3], because though it may not be true, it at least makes some predictions that can be analyzed and modeled to study the correspondence to our universe, and so can be falsified or supported by improved accuracy and predictive utility of these models vs observations.

[1] http://en.wikipedia.org/wiki/Anthropic_principle [2] http://en.wikipedia.org/wiki/Karl_Popper#Falsifiability.2Fpr... [3] http://en.wikipedia.org/wiki/Lee_Smolin#Cosmological_natural...

This is interesting. I had heard of this theory previously (Smolin), but didn't appreciate the Darwinian nature of it. You still get multiverses that each adopt their own distinct rules of physics, but natural selection plays in to how the universes are created. Some amount of information is transferred from the source universe to the one newly created, but the information is not lost -- something Susskin put forth some years ago by comparing the event horizon of a black hole to a hologram.

Even though the universe is (probably) infinite, this does of course not mean that it is infinitely repetitive.

Take for example the function y=x: even though the x-axis is infinite, no value of y occurs twice.

Also note that the argument can be made in time also. If time is infinite, events may occur repetitively indefinitely. But they may also not (for example, if the universe "crunches" and stays that way).

>Even though the universe is (probably) infinite, this does of course not mean that it is infinitely repetitive.

If the universe is infinite and consists of matter, I think you can safely say every feasible combination of particles repeats, infinite number of times.

Infinite sets does not equate to infinite possibility. Like you said, it only includes feasible combinations which is determined by our universe. If you roll a 6 sided die infinite times you will still never roll a 7.

So there's never a universe where your body is composed of ice-cream, as sadly it is most likely impossible in this universe.

>Like you said, it only includes feasible combinations which is determined by our universe

What do you think I was arguing? The OP argued "Even though the universe is (probably) infinite, this does of course not mean that it is infinitely repetitive". 'Repetitive' by definition means a feasible combination of atoms.

This isn't necessarily true. The article largely explains it. The interaction of particles trends to infinity faster than time.

Another way to think of it... Let's say that t is trending to infinity starting from 0. There are #s that will always be larger than t. Such as (t+1)^2.

One more way... Time is one dimension. The rest of space-time is 3 (at least). The size of possibilities is larger to 3 orders of magnitude.

And a last way... If it's feasible that matter can expand forever, then there's no way for the particles to repeat themselves. They just keep going and going...

Stop time right now. You now have an static, unchanging, universe. This universe is infinite in size, and roughly equally dense with matter and radiation across this infinity. You really want to make the argument that there isn't another Earth out there?

I wonder if the {uni|multi}verse might aggressively de-dupe entities within itself.

Kind of like the One-Electron idea (http://en.wikipedia.org/wiki/One-electron_universe), but on a larger scale.

To me it seems the article is completely mixing up two multiverse theories - one is that there are several essentially completely independent universes separated in space (or time) and the other is that there is no collapse of the wave function but all the possibilities encoded in the wave function are actually real and therefore many universes are kind of overlaid at the same time in the same space and in each universe you observe the wave function collapsed to a different state. Did I get it wrong or the article?

Max Tegmark, whose talk is summarized in this article if I understand correctly, describes four different types of Multiverse. This article presents three of them (levels I, II and III).

See Max Tegmark's webpage for more information and links on the subject:

http://space.mit.edu/home/tegmark/mathematical.html

Thanks, that is what I suspected. Maybe I just read the article to quickly but I completely missed the clear distinction between the different types of multiverses in the article.

I thought the whole implication of MWI is that every possibility does happen and universes are constantly splitting off. So there's an unlimited number of copies of you, some essentially identical, others experiencing inconceivable suffering or pleasure.

That's one way to think of it, but when dealing with infinity, one event isn't time dependent on another. Think of a reality (or infinite realities) where you remove the dimension of time entirely out of the equation.

Both the Schrodinger equation and inflationary cosmology predict alternate worlds filled with alternate yous. MWI refers to the former. The author of this piece is talking about the later.

If anyone is looking for a simple introduction to the Everett interpretation I'll point you to this short lecture by James Ladyman: https://www.youtube.com/watch?v=cgXVEeL9tzM

My understanding was that some theories of inflation require multiverses to exist. I have never heard that the Schrodinger equation nor inflationary cosmology themselves predict alternate worlds. Some theories require them (to get the math to fit), but there are definitely alternatives.

Many Worlds is one concept; this is another and quite different.

One more note on this.. fernly and others have correctly pointed out that these did come about as different theories, but there are physicists who have come to believe they are the same thing.

But if aiming at the "philosophical" impact and consequences, why focus on the one that doesn't have some potential for implications?

> we have every reason to believe there’s plenty more, and perhaps even infinitely more [Universe out there beyond the portion that’s accessible to us]

Which order of infinity do you mean when you say "infinitely more [space]" here? Aleph-One?

> we can extrapolate the Big Bang backwards to an arbitrarily hot, dense, expanding state, and what we find is that it didn’t get infinitely hot and dense early on

And what order of infinity here for the energy?

> the Universe was filled with energy inherent to space itself: a state that causes the Universe to expand at an exponential rate

If the infinity used to measure 2 different entities are of different orders, then there'd be at least an exponential differential between those entities. But what if the order of infinities is switched around between energy and space, could that then mean there's only one instance of inflated space in existence?

I've never read a discussion of multiverses, whether wrt inflation or quantum mechanics, where the order of infinity used is mentioned. Specifying what order of infinity is to be used for each measurement seems to be crucial to what result is infered.

>So realistically, we’re talking about at least 10^10^50 Universes that started off with initial conditions that might be very similar to our own.

Presumably, what follows from initial conditions is bound by determinism.

By the logic of that assumption, even if we assume an infinite set of initial conditions, can there really be alternate universes wherein everything is identical except for one miniscule thing, billions of years after initial conditions have unfolded?

>Presumably, initial conditions are slave to determinism just like anything else.

Why is everything slave to determinism? Isn't true randomness introduced to the system via randomness at the quantum level?

Unless the quantum level itself stems from initial conditions, and therefore is deterministic as well.

Also, I rephrased the line you quoted almost immediately after I posted it. Sorry about that.

I thought this clip [1] from a game was quite relevant.

[1] http://i.imgur.com/G5hXQ4C.gifv

A lot of more of the same 'Peek beyond the veil' of this reality type writing. Obviously a myopia exists on planet earth. Earth is a little bubble we have been floating in womb-like for aeons of years, and are aware, sometimes even at a very basic level that there's more out there. What I find awkward is that scale is seen as a scary thing. Space is often called a "final frontier", and the "last bastion of hope" and other scary things like that.

But you have to think of those first sailors who set out to discover the new worlds - they risked their lives - they were the original space monkeys. Sadly, ethical red tape won't allow a mass exodus to other stars - as the stock market would inevitably plunge, and there would be chaos.

The moment we get out of the tired economic model of scarcity, and start opting for abundance, is the moment we can leap towards other dimensions, and other worlds. But for now - we have an impotent attempt to understand the universe through a tired Hubble telescope, and a tired generation of rocket builders who read science fiction novels in secret and know there's another way out of this place.

> Sadly, ethical red tape won't allow a mass exodus to other stars - as the stock market would inevitably plunge, and there would be chaos.

What ethical red tape are you referring too? Because I can't quite think of any. And do you mind elaborate on the stock market too?

On the topic of scarcity vs abundance, fundamentally, there might be physical constraints that will never allow us to really be "abundance": space is big, really really big.

> space is big, really really big.

And the corollary to that: space is empty, really really empty. The government could encourage space exodus, even offer each citizen $1 million to leave. It's still just not possible right now.

Red tape: humans have been too busy fighting over land to make tremendous advances in the space programs. Compare money (our unit of abstract value) spent on weapons, internationally, compared to space exploration.

Interesting that this article discusses the Big Bang as happening after Inflation. I always assumed Inflation was the initial stage of the Big Bang. Is that just assumed in casual descriptions, but technically not true?

It is theorized that for a tiny fraction of time before the big bang the laws of physics were not the same as they are now, and if they had been such an expansion would not have taken place. This is the distinction they are likely trying to make.

Correct me if I'm wrong, since I only got my information from non-academic sources, but if I recall correctly the problem was that with the inflation, you would have to apply both the theory of general relativity (the science of the really big), and quantum theory (the science of the really small). In which case they totally don't work together and you would get really weird numbers.

Would a more logical explanation not be that our current theories are likely to be flawed, just like Newton's theory about gravity was flawed (but nevertheless incredibly useful) ?

More at its core is that it means that the expansion exceeded the cosmic speed limit, the speed of light. Two of the competing theories have been a rapid expansion (inflation) and another that two branes collided and the big bang started in an expanded state. As of late, it appears there has been more confirmation of the former rather than the latter. From what I've read, it is as another commenter noted -- the universe in it's earliest state did not yet conform to the rules of physics as we know them today. This early state is something on the order of the first trillionth of a trillionth of a trillionth of a second.

Is there? If you can't reach them, it doesn't matter. Articles that start with "is"..

this is the kind of stuff where I want to live old enough to see super AI solve this for us ;-)

if you want to meet another version of you, wait ten minutes. you'll be a different person thinking about something totally different. big deal.

You just blew my mind.

This is true. Especially evident if a day, week, or a year passes.

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