malpensante

skipping the issue whether the multiverse view should be taken or not (the view that reality is not composed of a single universe but a large multiverse of infinite parallel universes), i would like to discuss one idea that david deutsch writes in his book "the fabric of reality", that interests me because i am a student of general biological science. here is the idea:

in a single universe, the most striking structures are galaxies and clusters of galaxies. across parallel universes, however, these have no structure. where there is a galaxy in one universe, a myriad galaxies with quite different geographies are stacked in the multiverse. and so it is everywhere in the multiverse. nothing extends far into other universes without its detailded structure changing unrecognizably. except, that is, in those few places where there is embodied knowledge. in such places, objects extend recognizably across large nmbers of universes. perhaps the earth is the only such place in our universe, at present. in any case, such places stand out, in the sense i have described, as the location of the processes - life, and thought - that have generated the largest distincitive sturctures in the multiverse.

the example deutsch gives is the following:

take two short DNA segments from an organism, one is a gene and the other is junk DNA (non-gene). if both segments have the same sequence, then they are physically identical, but only within a single universe, and they are physically different (the physical feature of embodied knowledge is more apparent) when looked at across parallel universes (you can't look at anything from outside your own universe, so it is a thought experiment). the difference across the multiverse is that the non-gene segment's lack of function has allowed it to mutate and have a different sequence in most parallel universes, while the gene segment's function and vitality for the organism, requires that the sequence be intact across the parallel universes in which the samples have been taken. so this gene segment has the emergent property that it creates a big "crystal" that extends across a wider range of universes.

this is the example for the idea, from which deutsch argues that life is a fundamental physical phenomenon.

excreationist

malpensante:
I disagree... I think things like stars would be amongst the largest distinctive structures in the universe. They'd remain relatively unchaged for large amounts of time.
On the other hand, things like human culture can change dramatically in small periods of time - e.g. someone might accidently invent something, etc. And life can be quite sensitive to change... e.g. small changes in the environment can mean the difference between life and death.

I think it would be inevitable for life to emerge within parts of the multiverse assuming that some of the universes have fairly stable/consistent physics (for things like DNA) and enough energy, and particles, etc. But I don't think that the multiverse places a greater emphasis on creating or giving freedom to life than giving freedom to galaxies to have alternate histories.

Intelligent people in many multiverses would have equivalent kinds of knowledge in their brain, but that is only because they experienced the same patterns in their environment and learnt the same patterns.

As far as DNA replication goes, it is kind of a super-complex chemical process, where the same molecules tend to form but the rain cycle involves a cycle too, and the H2O in rain droplets are much more abundant.

"...life, and thought - that have generated the largest distincitive sturctures in the multiverse."

Maybe you're talking about how complex they need to be in order to "work"... stars can be perfect spheres (that might need to rotate) and still "work" about the same... but life can't be simplified very much at all. Maybe I'm missing what your point was...

malpensante

i can imagine a large transuniversal "knowledge crystal" that looks like a fleeting event in a single universe, can't you?

i can also imagine a structure of eons of age which still is random enough for its structure to be limited to one universe within the multiverse, can't you?

biospheres and galaxies are equally free to have alternate histories, and in fact i think what deutsch's idea is about is that biospheres have less alternate histories, because they will variate less randomly across universes.

you say that to have the same knowledge, two alternate-universal humans would need to share the same patterns, but i think knowledge is actually about going beyond possibilities (overcoming combinatorial explosion problems), which means that it is perfectly possible for the knowledge of two human beings about a subject to be functionally equal even when they have not shared the same environment. you and i both know english, and were born in different continents, it's the same pattern, but they are different environments.

so, let's get back a little: would knowledge form a transuniversal crystal only when across the universes occupied by the crystal we can see the same environment (including galaxy geography)? no.
would knowledge form a transuniversal crystal only when across the universes occupied by the crystal we can see the same pattern (eg. the same random organizing pples for clusters of stars and galaxies)? i don't know.

but even if the answer were yes, the galactical structure would have varied within the particular transuniversal knowledge crystal. of course, one could say that conversely, many alternate biosphere histories might vary within some specific transuniversal galaxy shape crystal, but this is a parochial way of seeing things. the crystals are not superficial properties of the universes across which they are found, but fundamental properties, concerning the overall structure of such universes.

knowledge crystals all share the property that they all change the shape of the individual universes they occupy, because the knowledge embodiment physical structures possess more causal properties than the galaxy cluster physical structures. i will need to state a controversial claim to drive the point:

the set of all universes where there is life have a different kind of development from the set of all universes where there is not life.

an example (which comes from deutsch too): if life would have been wiped from earth , the sun would inevitably die, destroying the earth, and our galaxy would be just the same as every other galaxy we see. but the fact that there is life on earth poses the question: will the amount of knowledge (which is at present increasing so fast) be big enough when the time has come for us to decide whether the sun eats the earth in order to save life? or, will the future knowledge allow us to escape the earth and colonize other planetary systems and perhaps the whole galaxy, giving it a very different look from the one every other universe now has? the fact that we can pose the question means that the mere presence of life is a fundamental causal factor for the development of the whole universe which contains it.

so, the overall aspect of the universes across which we find knowledge crystals is more homologous than that of those across which we find galaxy shape crystals.

i didn't understand your comment on how complex something must be to work, and how it applies to deutsch's idea.

excreationist

malpensante:
Actually I think they would have the same amount of alternate histories... it's just that many would be identical. I don't think there is an intelligent being merging identical parallel universes...

I didn't say that you need to have identical environments to have equivalent patterns in your brain... e.g. you could have two people who expect objects to drop when you let go of it... one person could have been raised on the Moon and only knows English... the other could have been raised in the desert and only knows a tribal language. The people both have experiences involving objects falling although the acceleration due to gravity is different on the Moon and on the Earth.

malpensante

would biospheres and galaxies have the same number of alternate histories? in some sense yes, in another, i don't know: both would have an infinite number of alternate histories, but i don't know of a reason to rule out that one infinite number may be transfinitely larger than another infinite number.

you say: "i don't think there is an intelligent being merging identical parallel universes".
i don't know what you mean, but if you're talking about a transuniversal experiencer, i agree with you. if you mean that any two identical universes must contain all different intelligent beings, i don't know why you would say that.

i know you said that two identical intelligent beings don't require the same environment, but the same patterns, but i hope you understood when i said that even so, the "cells" composing knowledge crystals would be more intra-universally homologous, and therefore, a knowledge crystal would be a bigger transuniversal structure than a galaxy shape crystal.

i didn't understand your comment on how complex something must be to work, and how it applies to deutsch's idea. do you agree with the idea?

excreationist

malpensante:
I'm starting to get confused by where this is all leading... so I'll get back to what I said in my last post:
"Actually I think they would have the same amount of alternate histories..."
Assuming that quantum fluctuations occur at a fairly constant rate then there would be roughly the same amount of change in two things that have an equal amount of matter and time... (e.g. a bit of a star and a bit of a biosphere). But perhaps there are more quantum fluctuations inside stars... so they would be the source of more divergences(?). Quantum fluctuations would be the source of true randomness and any divergence from deterministic physics so if some object has more quantum fluctuations (maybe superhot stars?) it would have more alternate histories, although most of them might be quite boring.

"it's just that many would be identical."
This was in response to "...biospheres have less alternate histories, because they will variate less randomly across universes...". This might be because living systems try to bring order to the environment which would be affected by quantum fluctuations. So the life is sort of "steering" things in certain directions rather than going with the flow like a star.
To quote what I wrote again....
"I think they would have the same amount of alternate histories [assuming they experience the same amount of quantum fluctuations]... it's just that many [of the alternate histories] would be identical."
Let's say that there is a particle that randomly moves either left or right, in each unit of time. Let's say that there are two versions of this example - one where the particle moves freely, and the other where some system (e.g. life) keeps it near the equilibrium point (position 0). Let's say the life system detects its previous position, then moves it one unit to the left or right (or not at all) in the direction of the equilibrium point (position 0). Then there is a random change (the particle moves left or right, due to quantum fluctuations).
Obviously this example isn't realistic but it was the best I could think of.

Example 1 - Where the particle can move freely...

(after 1 time unit...)
Universe A position 1.
Universe B position -1.

(after 2 time units...)
Universe AA position 2.
Universe AB position 0.
Universe BA position 0.
Universe BB position -2.

(after 3 time units...)
Universe AAA position 3.
Universe AAB position 1.
Universe ABA position 1.
Universe ABB position -1.
Universe BAA position 1.
Universe BAB position -1.
Universe BBA position -1.
Universe BBB position -3.

(after 4 time units...)
Universe AAAA position 4.
Universe AAAB position 2.
Universe AABA position 2.
Universe AABB position 0.
Universe ABAA position 2.
Universe ABAB position 0.
Universe ABBA position 0.
Universe ABBB position -2.
Universe BAAA position 2.
Universe BAAB position 0.
Universe BABA position 0.
Universe BABB position -2.
Universe BBAA position 0.
Universe BBAB position -2.
Universe BBBA position -2.
Universe BBBB position -4.

So after 4 time units, there is one universe with position 4, four with position 2, six with position 0, four with position -2 and one with position -4.

Example 1 - Where the particle is affected by the life form...

(after 1 time unit...)
Universe A position 1. (before quantum fluctuation: 0)
Universe B position -1. (before quantum fluctuation: 0)

(after 2 time units...)
Universe AA position 1. (before quantum fluctuation: 0)
Universe AB position -1. (before quantum fluctuation: 0)
Universe BA position 1. (before quantum fluctuation: 0)
Universe BB position -1. (before quantum fluctuation: 0)

(after 3 time units...)
Universe AAA position 1. (before quantum fluctuation: 0)
Universe AAB position -1. (before quantum fluctuation: 0)
Universe ABA position 1. (before quantum fluctuation: 0)
Universe ABB position -1. (before quantum fluctuation: 0)
Universe BAA position 1. (before quantum fluctuation: 0)
Universe BAB position -1. (before quantum fluctuation: 0)
Universe BBA position 1. (before quantum fluctuation: 0)
Universe BBB position -1. (before quantum fluctuation: 0)

(after 4 time units...)
Universe AAAA position 1. (before quantum fluctuation: 0)
Universe AAAB position -1. (before quantum fluctuation: 0)
Universe AABA position 1. (before quantum fluctuation: 0)
Universe AABB position -1. (before quantum fluctuation: 0)
Universe ABAA position 1. (before quantum fluctuation: 0)
Universe ABAB position -1. (before quantum fluctuation: 0)
Universe ABBA position 1. (before quantum fluctuation: 0)
Universe ABBB position -1. (before quantum fluctuation: 0)
Universe BAAA position 1. (before quantum fluctuation: 0)
Universe BAAB position -1. (before quantum fluctuation: 0)
Universe BABA position 1. (before quantum fluctuation: 0)
Universe BABB position -1. (before quantum fluctuation: 0)
Universe BBAA position 1. (before quantum fluctuation: 0)
Universe BBAB position -1. (before quantum fluctuation: 0)
Universe BBBA position 1. (before quantum fluctuation: 0)
Universe BBBB position -1. (before quantum fluctuation: 0)

After 4 time units, the particle is at position 1 in 8 universes, and at position -1 in 8 universes.

Anyway, in the example with life, the universes after 4 units of time were less varied - though both examples experienced the same amount of quantum fluctuation. After 4 units of time there are 16 parallel universes... many of them are identical... but it takes an intelligent person to say "well in the life example, there were only two different types of universes".

"I don't think there is an intelligent being merging identical parallel universes... "
When I said that, I meant that I don't think that an intelligent force is merging identical universes... so in the life example, there are 16 parallel universes - I think they would remain as 16 separate universes rather than being automatically collapsed to two somehow.

The intelligent beings would be identical but they would still be distinct, since they are in two different universes - i.e. they can be differentiated between. In the life example, after 4 units of time there are two types of outcome, but each actually experienced a different history! e.g. in universe AAAA and universe BBBA, the particle eventually ends up at position 1. (let's say that the positive direction is right and the negative direction is left).
In universe AAAA,
1. life doesn't move the particle, quantum fluctuation moves it right.
2. life moves the particle left, quantum fluctuation moves it right.
3. life moves the particle left, quantum fluctuation moves it right.
4. life moves the particle left, quantum fluctuation moves it right.

And in universe BBBA,
1. life doesn't move the particle, quantum fluctuation moves it left.
2. life moves the particle right, quantum fluctuation moves it left.
3. life moves the particle right, quantum fluctuation moves it left.
4. life moves the particle left, quantum fluctuation moves it right.

So they had histories that involved some different events, even though they are physically identical at this point in time. It is sort of like having two physical objects that are (more or less) physically identical, except that they occupy different positions in space.

Perhaps, but I don't see how the size of these "crystals" is relevant to anything in physics... I guess it might just be something interesting to think about.

Stars can change a lot and still be stars. If living things change much, they are no longer living. If your brain changes much then it no longer works properly (e.g. if you had a monkey's brain or you were in an accident).
Maybe it doesn't have anything to do with his idea. I just brought up that idea in an attempt to understand what the topic was about. Don't worry about that part of my post.

malpensante

so, you seem to agree with the idea, but think it lacks more than a contemplational value. i think it does have that value, but am eager to believe that there must be many other practical implications. as dr michael lockwood said, in a review on the book by deutsch says:
it gives us reason for thinking that intelligent life, so far from being merely a 'scum' that occasionally forms on the surface of insignificant planets, is destined to take centre stage in the evolving cosmic drama."

i'll finish this post later.