Explaining the Quantum Mystery: Are Parallel Universes the Answer?

[EnumaElish]

So if there are two possible outcomes and they have an equal probability of occurring then the universe bifurcates into one each for both of the outcomes. But what if the probability is not equal, then what? What about continuous ranges of possible outcomes where the probability of anyone of them is zero? Is this what the mathematicians have worked out?

Wouldn't that imply one can get half pregnant?

 

[Moonbear]

But some of the most unlikely outcomes (from our perspective) would appear miraculous. If all possible outcomes actually happen then it follows that highly unlikely results should be as common as expected results as the highly unusual should be mixed equally with the usual.

If the outcome is possible, why would it be "miraculous?" Of course, what one considers a miracle depends on perspective as well. As long as it doesn't violate the physical bounds, which would make it impossible rather than possible, then there would be nothing miraculous about it happening.

For example there tends to be very few survivors from a plane crash. Surviving is a possibility so in the multiverse, assuming each universe is of equal merit, there must be a branch of reality where all the passengers survive and this possibility should have equal weight to none surviving yet we never see the result where all the passengers survive and so it seems (again based on our expectations) all of the highly unlikely outcomes end up in someone else's universe. So why not in ours?

Okay, here's the way I'm understanding it, which might help (and I'll hope ST will jump in if I'm way off base). The possibility of survival is dependent on all the other events leading up to it, which I presume is why this is a complex mathematical model to develop. Think of it as a series of if-then statements. The plane may crash, or it might not crash. If it does crash, then it might explode on impact, or it might not. If it explodes on impact, there might be hot enough temperatures to fry everyone inside (at which point survivors becomes an impossible outcome) or it might not (survivors is a possible outcome). If it doesn't, then the cabin might fill with toxic smoke, or it might not. If it does, for every passenger still alive (dependent upon where they were seated...and any of those passengers may or may not have gotten that first class upgrade to put them in the ill-fated seat...) they may or may not be able to hold their breath long enough to get to the exit, that exit may or may not be blocked, etc.

So, it wouldn't just be, plane crashes and any number of passengers survive, but rather that the entire chain of events that allows all the passengers to survive must occur, which is far less likely to occur than a 50/50 survive or not survive outcome. At each bifurcation, only the possible next steps can occur, and you can't just skip a step, because that would violate the physical rules. Having to go through every small step prevents an impossible outcome from happening, thus no miracles.

Just to try to make the picture a bit clearer, another way to look at it would be that indeed, there ARE rare occurrences of a plane crashing and everyone surviving, because all the other events that are part of that crash make it possible for everyone to survive...there was enough time to dump fuel, a long flat landing area, a highly skilled pilot, a skilled flight crew and passengers who all follow instructions to prepare for the crash, and emergency responders contacted as soon as the pilot knows they're in trouble, and get through all the traffic in time to be ready as soon as the plane hits the ground.

It's sort of like winning the lottery. The probability that it will happen for anyone person buying a ticket is low, but someone does win, and it could be someone buying their first lottery ticket ever, while someone else playing every week their entire life may never win anything. There's nothing that says that everyone who plays gets an equal amount of wins and loses, even if their chance of winning is all the same.

 

[Gokul43201]

So if there are two possible outcomes and they have an equal probability of occurring then the universe bifurcates into one each for both of the outcomes. But what if the probability is not equal, then what?

How many pairs of events can you think of where the two members have an exactly equal probability of occurance? I can't think of any.

In any case, the universe never bifurcates into any finite number.

What about continuous ranges of possible outcomes where the probability of anyone of them is zero? Is this what the mathematicians have worked out?

This is covered adequately by positing an infinite number of bifurcations.

PS: I think this takes care of Art's objection too.

 

[Ivan Seeking]

Maybe I should have said that outside this universe is 'unrealizable' and as such, one can only 'speculate' as one would do about an 'afterlife', which anyone could start to argue is simply a parallel universe.

The difference is that so far we don't need to postulate the existence of heaven in order to explain experimental results. The motivation for this is science and not faith based doctrine.

Would those models also speculate that the same 'laws' exist, e.g. spin, mass, matter, e/m, quark charge, color, m_e/m_p, . . . . are the same or different?

Based on what I can remember...

I don't think we know why the physical constants have the values that they do, so we can't say what range of values are possible in any universe. However, I have heard of one theory or hypothesis, I guess one version of the MWT, that suggests that there are many failed universes where the physical constants were incompatible with the formation of atoms, etc. And this goes back to the question of the likelihood that we should even exist. No matter how unlikely it is that everything is just right so that the universe can exist as we know it, and it has been argued to be very unlikely since the slighest variation in any constant would prevent our existence, or atoms, or even the universe itself, our existence is guaranteed by an infinite number of failed universes. As for the laws of physics changing -can another universe exist under a different set of physical laws - I'm not even going to try to touch that one, but I'm sure that someone has before.

 

[vanesch]

As some of you know, I have been defending the many worlds interpretation of quantum theory several times on the QF forum, even to the point where I made other mentors probably a bit nervous about it. I've also said and -re-said everything that I think about it, so I'm now trying to avoid to get absorbed into these discussions for the n-th time, as this takes a lot of time on my side, and is just repeating what I said before.

The point of the Many Worlds interpretation, crazy as it may sound, is that it adheres as closely as possible to the basic postulates on which the entire formalism of quantum theory is based. So in as much as one takes these postulates as telling us something about how nature "is", and not just as "how it behaves", you come very naturally to the MWI - in my opinion, it is even unavoidable in as much as one takes the founding postulates of quantum theory as it is today, litterally. The whole discussion is of course in how much one has to take this literally.

I often compare the MWI of the formalism of quantum theory to the "spacetime" view of relativity. In as much as we picture ourselves a 4-dimensional "physical" spacetime, because this is so deeply build into the entire formalism of relativity, in the same way, one arrives at "many worlds" in the formalism of quantum theory, because the superposition principle resides so deeply in it.

But that's where it stops. The MWI is just a very natural way to look upon the *formalism* of quantum theory as something "physical", and any way to get rid of the superposition (of many worlds) needs one to introduce some "ugly deviation from the basic formalism". But it can be done. Each way has then its own problems and merits. There are ways to modify the quantum formalism into another formalism, with the introduction of other physical entities, which can get rid of superposition. These views then get into troubles with the basic physical ideas in relativity. There is also the view that the formalism of quantum theory doesn't tell us anything about how nature is, but only about what we observe of nature - that's essentially Copenhagen. As such, Copenhagen is nothing more or less but the view that nature is "classical with exceptions" and that there's no physical description of the exceptions, but just a way to calculate the resulting observation, and that's what quantum mechanics is all about.

All this means that MWI is a natural interpretation of a formalism, if we take it to describe a physical situation, and not just as a tool to calculate results of observations without any link to what might happen underneath.

This also means that claims from certain MWI proponents such as Deutch are highly exaggerated, or even wrong. As others said here before, one cannot prove the MWI interpretation. One can at best prove the agreement of observation with predictions of QM in different situations, which might eventually reject ALTERATIONS from the standard formalism, but one will never be able to PROVE MWI, given that it is an INTERPRETATION of a formalism.

My view on the utility of MWI is not there. It is that it is a natural view on the current formalism, and as such, imagining that "this is the way things are" helps one devellop an intuition for the current formalism, avoiding many of its so-called "paradoxes" such as the EPR "paradox" of which the "solution" is pretty obvious in an MWI setting. So I see MWI as a useful mental exercise to help one understand the workings of the current quantum formalism, in the same way as the "spacetime" view helps one get an intuition for relativity. No more, no less.

How nature "really" is, nobody knows.

 

[Zantra]

If this theory holds then it would mean something approaching an infinite number of universes assuming that each path splits off to an almost infinite series of choices in an achilles reference, where choices get broken down by degrees almost to the point of redundancy. Sure, if you can only choose vanilla or chocolate, it's a simple split. But go to baskin robins and you'll start to get a headache. Factor in things like genome sequencing where the permutations become mind boggling... and you see where I'm going with this.There are a trillion trillion you's out there carrying out every possible(which inof itself can become infinite) choice you've ever been faced with. To wrap it up, let's just say every permutation of every variable in the universe since time began.

nahhhhhhh...

I think Jet Li did this already in "the one";)

 

[Art]

If the outcome is possible, why would it be "miraculous?" Of course, what one considers a miracle depends on perspective as well. As long as it doesn't violate the physical bounds, which would make it impossible rather than possible, then there would be nothing miraculous about it happening.


Okay, here's the way I'm understanding it, which might help (and I'll hope ST will jump in if I'm way off base). The possibility of survival is dependent on all the other events leading up to it, which I presume is why this is a complex mathematical model to develop.

The plane crash scenario wasn't a very clear example of the idea I was trying to convey. I think my post #26 better explains what I meant to say. Irrelevant to the likelihood of an outcome once the possibility exists a universe catering for that outcome comes into being and we should then have an equal chance of following what we regard as an unlikely outcome as a likely outcome. Otherwise just as in our universe where the 'likely' happens most of the time other versions of ourselves would inhabit universes which suffer from a surplus of 'unlikely' outcomes which begs the question why should our universe be favored?

by Enuma Art, technically what you are saying is outcomes are distributed uniformly across universes. An alternative would be they are distributed normally across universes with a probability mass centered around the "mean outcome" that thins out as one gets farther from the mean. Space Tiger's explanation favors a normal distribution over a uniform distribution.

Again this seems to me to suggest a special status for our particular universe over the others.

 

[vanesch]

If this theory holds then it would mean something approaching an infinite number of universes assuming that each path splits off to an almost infinite series of choices in an achilles reference, where choices get broken down by degrees almost to the point of redundancy. Sure, if you can only choose vanilla or chocolate, it's a simple split. But go to baskin robins and you'll start to get a headache. Factor in things like genome sequencing where the permutations become mind boggling... and you see where I'm going with this.There are a trillion trillion you's out there carrying out every possible(which inof itself can become infinite) choice you've ever been faced with. To wrap it up, let's just say every permutation of every variable in the universe since time began.

Point is, this is not how you should look upon MWI. You should think of "the wavefunction of the universe" (a vector in the hilbert space of the quantum system which is "the universe" - it's a VERY big space), which has *components* (big or small) in about every subspace which corresponds to "a classical universe configuration", and one of them is where you "live in". So the mind-boggling number you find is the number of thinkable classically-looking configurations of the universe, which by themselves are only a tiny number of the possible quantum configurations of the universe - and that set of possibilities is nothing but the hilbert space of the universe, when you basically apply the postulates of quantum theory to a system called "the universe". So that very big number was built in quantum theory from the start, when setting up the hilbert space.

The so-called "split of worlds" is only a colloquial way of talking, but there's no "physical process which corresponds to a split". You simply have the total state vector which wobbles around, and has more or less important components in subspaces which are called "classical worlds".

Compare this to the "single particle universe". We have a statevector which is just an element of the standard hilbert space of a single particle. In that hilbert space, there are states which correspond more or less to "classical particle states", which means: particles with rather well-defined position and momentum. They are "coherent states" in the hilbert space. Now, the state vector can be decomposed onto these coherent states, and you could say that the particle is "in different worlds at the same time", meaning, has different components equal to different coherent states at the same time. This is what happens in a 2-slit experiment for instance. At a certain point, the quantum state of the particle corresponds to a superposition of two "classical" states, namely a trajectory through the left slit, and a trajectory through the right slit. But formally, you simply have a state vector which evolves continuously, following the Schroedinger equation, and which can be written down in a specific decomposition which we happen to call "trajectories" (or "worlds").

 

[vanesch]

Otherwise just as in our universe where the 'likely' happens most of the time other versions of ourselves would inhabit universes which suffer from a surplus of 'unlikely' outcomes which begs the question why should our universe be favored?

Again this seems to me to suggest a special status for our particular universe over the others.

This is indeed the central "problem" of MWI interpretations: how do we make different probabilities emerge from an a priori equal distribution of worlds, and this is where the whole interpretation of the concept of "observation" (subjective observation) resides. There are attempts, some of which are promising, to try to follow the path, that there are MORE likely worlds than unlikely worlds. So if somehow your *chance to subjectively experience* a world is uniformly distributed over all worlds, then if there are more that are likely, you will more likely experience a world which is more likely.

Personally, I don't find this a useful exercise, because you have already to introduce an "a priori" probability distribution, namely the UNIFORM probability for you to experience a world. If we are going to introduce a probability for you to experience a world, why not make it the right one immediately ? Why simply not say that the probability for you to experience a certain world equals the probability given by quantum theory for this world (and not: is uniform, and then go and try to estimate the NUMBER of these worlds to transform this uniform distribution into the "right" one).

 

[Astronuc]

The difference is that so far we don't need to postulate the existence of heaven in order to explain experimental results. The motivation for this is science and not faith based doctrine.

I'm playing 's advocate.

I'm reacting to 'speculative' science in which mathematical models are developed and applied to outside this universe. It seems as 'make-believe' as any other 'belief', regardless that the basis is science.

 

[vanesch]

I'm playing 's advocate.

I'm reacting to 'speculative' science in which mathematical models are developed and applied to outside this universe. It seems as 'make-believe' as any other 'belief', regardless that the basis is science.

This is one of the (many) misunderstandings of MWI, namely that one has *introduced*, as extra postulates, somewhat arbitrarily, those extra worlds. As if someone came along and said: hey, what if we would now introduce extra worlds, how would that behave ?

But that's not the origin of the MWI in quantum theory. In quantum theory, the superposition of many worlds comes out naturally, and what we usually do is to *discard* all but one of them (the so-called projection postulate). Now, that projection postulate screws up quite a lot. It screws up the Schroedinger equation, for one. So if we consider that quantum mechanics is giving us some kind of "mechanism" of how nature works, then there ought to be a mechanism that does this projection, and it is easily shown that the projection and schroedinger's equation are incompatible, no matter how complicated the system is made. It also screws up a nice aspect of quantum theory, which makes its dynamics local. The projection postulate is bluntly non-local. From this follow all these weird situations like EPR. So the MWI approach is simply: let's suppose that nature ALWAYS works the same way, according to the Schroedinger equation. But then you get the strange situation, if you work this out mathematically, that your measurement apparatus, and by extension, the consious observer, ends up in a quantum state which is not classical, but is a superposition of classical states, each with "different outcomes". And that's where Everett made his point: a subjective observer is not corresponding to the superposition of all these observer states, but just to one single classical projection of it. If you make that hypothesis, then you see that to this subjective observer, everything happens AS IF projection occurs in most cases.

In other words, MWI is nothing else but a (desperate ?) attempt to try to make physical sense of the quantum formalism as it is. It didn't "invent" anything beyond it.

As I said before, there are different ways out: you can simply say that the quantum formalism is not hitting the nail on its head, and one should look for a different formalism which is empirically close enough to quantum theory in order to be experimentally compatible with it, but with a totally different formal machine and interpretation. Or you can simply say that quantum mechanics describes observations, but has nothing to do with how nature works, which is maybe somehow undescribable. So it is just a calculational tool to find out numbers which correspond to observations, but has not descriptive value at all, because maybe nature cannot be described beyond the classical realm. This is the Copenhagen view.
These are other ways to tackle the problem.

 

[chronon]

There was a conference in Oxford in July to mark the 50th anniversary of the Everett interpretation, which may have lead to the New Scientist article. Further information about this conference, including videos of the talks can be found at

http://users.ox.ac.uk/~everett/

 

[Moonbear]

The plane crash scenario wasn't a very clear example of the idea I was trying to convey. I think my post #26 better explains what I meant to say. Irrelevant to the likelihood of an outcome once the possibility exists a universe catering for that outcome comes into being and we should then have an equal chance of following what we regard as an unlikely outcome as a likely outcome. Otherwise just as in our universe where the 'likely' happens most of the time other versions of ourselves would inhabit universes which suffer from a surplus of 'unlikely' outcomes which begs the question why should our universe be favored?

Again this seems to me to suggest a special status for our particular universe over the others.

This is indeed the central "problem" of MWI interpretations: how do we make different probabilities emerge from an a priori equal distribution of worlds, and this is where the whole interpretation of the concept of "observation" (subjective observation) resides. There are attempts, some of which are promising, to try to follow the path, that there are MORE likely worlds than unlikely worlds. So if somehow your *chance to subjectively experience* a world is uniformly distributed over all worlds, then if there are more that are likely, you will more likely experience a world which is more likely.

Personally, I don't find this a useful exercise, because you have already to introduce an "a priori" probability distribution, namely the UNIFORM probability for you to experience a world. If we are going to introduce a probability for you to experience a world, why not make it the right one immediately ? Why simply not say that the probability for you to experience a certain world equals the probability given by quantum theory for this world (and not: is uniform, and then go and try to estimate the NUMBER of these worlds to transform this uniform distribution into the "right" one).

I'm really not seeing at all how another universe would get more "unlikely" outcomes. Wouldn't that simply mean we've missed a step in the sequence of events somewhere if an outcome seems "unlikely," instead of "likely." And, wouldn't that be more subjective, based on experience anyway? If, for example, every time a plane crashed, there were many survivors and very few people ever died, wouldn't your subjective experience determine that it's more likely that people would survive a plane crash than die in it, and it would be a surprising and unlikely outcome that a crash happened where most of the occupants died? If the splits all occur along divisions of possible outcomes, there's no reason to think any of the outcomes would appear unlikely. Only those that meet certain preceding conditions could split, not every path that has diverged on an earlier point, I would think. I'm not sure if that's where you're getting hung up.

In the airplane scenario, just because it's easier to keep going with the same path of discussion for me, once the split occurs at the crash or not crash division, all those universes in which the plane did not crash continue on happily without any further bifurcations related to that event, and only those in which the plane crashes would then continue with bifurcations related to the events of the crash. You wouldn't get a scenario where the plane doesn't crash, lands safely on the ground, and all the passengers are inexplicably dead to balance out all the passengers surviving the fiery crash in another universe.

But, if I'm understanding Vanesch's explanation correctly, there are two more wrinkles here. First, it's not necessarily true that all these universes REALLY exist, just that it's a way of thinking about the mathematical probabilities and easier to consider they MIGHT exist (I'm not totally sure if I'm understanding him on this point or not). Second, we can't assume every outcome is an even probability. We might be playing with loaded dice. Does every time an outcome happens in a particular direction weight the probabilities of future events toward following a similar outcome?

 

[Astronuc]

Is this a fair description of MWI?

http://en.wikipedia.org/wiki/Many-worlds_interpretation

http://en.wikipedia.org/wiki/Multiverse


It would appear that in THIS universe, when the time comes, i.e. at the present moment - there is only one outcome - and time marches on.

I look at this speculative work in the context of the current condition of humanity - e.g. the ongoing warfare and violence in the world - and wonder.

How will the MWI work benefit the world/humanity? How will it help solve the energy and limited resources problems? . . . .

 

[EnumaElish]

How will the MWI work benefit the world/humanity? How will it help solve the energy and limited resources problems? . . . .

If we could negotiate a deal with a parallel universe that is energy rich but with very few people, we could send people to work as guest laborers there, in exchange for cheap energy?

 

[vanesch]

How will the MWI work benefit the world/humanity? How will it help solve the energy and limited resources problems? . . . .

By boosting the sales of weird pop-science books, and hence contribute to the world economy ?

I think that the Wiki entry is pretty good on MWI. It is my preferred way of thinking of *the quantum formalism*. As a matter of fact, many very strange quantum properties, and many strange quantum experiments which have been performed, find a very natural and clear explanation when you do "MWI-think" ; the two foremost examples are the top of bizarrerie: EPR-type experiments (spooky action at a distance) and quantum eraser experiments.
As such, MWI-think is enlightening to study the formalism of quantum theory. Whether the real world is anything like this, I haven't gotten any clue. It puts the scientific endevour in some more modest perspective.

 

[Art]

Moonbear imagine you are walking down a road and it forks into 2, suddenly there are also 2 of you. One takes one turn and the other you takes the other. Next these 2 come to another set of forks so there are now 4 yous each on one of the new tracks. This continues on until there zillions of you.

Now at each junction there was a 50:50 chance which path the 'primary' you ended up on as you had no way of knowing which path represented the most likely (as you had no knowledge or say in the universe splitting) so why is it that when you look back over your life nearly all the paths you ended up on happened to represent the most likely? Also it follows that if the 'primary' you hogged all of the most likely paths your doubles were left to take the less likely paths so when they look back over their lives they would see a string of unlikely happenings.

 

[rewebster]

When I think about MWI, for some reason, a Fellini film comes to mind. Seeing a psychiatrist or working for the film/TV industry seems appropriate for those still interested in it.

(emote added for those who may be offended)

--------------------------

(thinking about/paraphrasing the Disraeli quote)

http://www.brainyquote.com/quotes/quotes/b/benjamindi142175.html

---------------------------------------
he has some good ones:

http://www.brainyquote.com/quotes/authors/b/benjamin_disraeli.html

 

[SpaceTiger]

Personally, I don't find this a useful exercise, because you have already to introduce an "a priori" probability distribution, namely the UNIFORM probability for you to experience a world. If we are going to introduce a probability for you to experience a world, why not make it the right one immediately ? Why simply not say that the probability for you to experience a certain world equals the probability given by quantum theory for this world (and not: is uniform, and then go and try to estimate the NUMBER of these worlds to transform this uniform distribution into the "right" one).

I think we're on the same page here, though I'm not nearly as familiar with the details of the MWI debate, so bear with me. I view the MWI as a way to explain the intrinsic uncertainties and paradoxes in quantum behavior that have already been observed, not a prediction for the outcome of those uncertainties. If we continue to view the multiverse objectively, then there should be no preferred set of outcomes beyond the actual quantum probabilities.

Of course, subjective experience can throw a wrench into all this with things like quantum immortality, but then the discussion ventures from science as we know it. If the outcome of an experiment cannot be objectively agreed upon, there's not much point in performing it.

 

[Evo]

so why is it that when you look back over your life nearly all the paths you ended up on happened to represent the most likely? Also it follows that if the 'primary' you hogged all of the most likely paths your doubles were left to take the less likely paths so when they look back over their lives they would see a string of unlikely happenings.

Why would you assume a person would always take the "most likely" path? Most likely to whom? People make good and bad decisions, so if you make the wrong decision, then the "other" you makes the right decision. I would say my other selves are doing a lot better than I am.

I also don't know why you think this reality is the "primary" or "special" one. It's just the only one we know. Look at all that is wrong in this world and tell me if there were alternate worlds that this one would be the best.

 

[rewebster]

Why would you assume a person would always take the "most likely" path? Most likely to whom? People make good and bad decisions, so if you make the wrong decision, then the "other" you makes the right decision. I would say my other selves are doing a lot better than I am.
I also don't know why you think this reality is the "primary" or "special" one. It's just the only one we know. Look at all that is wrong in this world and tell me if there were alternate worlds that this one would be the best.

so...


...just how is that arm doing?

(and the 'move'?)

 

[Jimmy Snyder]

No one ever thinks their own universe is strange. Physics is based on experience. In other universes where the probabilities are different, they have a different quantum mechanics with the correct values in it for their situation. They would be floored if they could get a load of our 'normal' universe.

 

[Evo]

so...


...just how is that arm doing?

(and the 'move'?)

Not good for both. I'll update the moving thread.

 

[Art]

Why would you assume a person would always take the "most likely" path? Most likely to whom? People make good and bad decisions, so if you make the wrong decision, then the "other" you makes the right decision. I would say my other selves are doing a lot better than I am.

I also don't know why you think this reality is the "primary" or "special" one. It's just the only one we know. Look at all that is wrong in this world and tell me if there were alternate worlds that this one would be the best.

I never mentioned good or bad decisions. Why would I? It has absolutely nothing to do with the subject.

 

[Burnsys]

I'm really not seeing at all how another universe would get more "unlikely" outcomes. Wouldn't that simply mean we've missed a step in the sequence of events somewhere if an outcome seems "unlikely," instead of "likely." And, wouldn't that be more subjective, based on experience anyway? If, for example, every time a plane crashed, there were many survivors and very few people ever died, wouldn't your subjective experience determine that it's more likely that people would survive a plane crash than die in it, and it would be a surprising and unlikely outcome that a crash happened where most of the occupants died? If the splits all occur along divisions of possible outcomes, there's no reason to think any of the outcomes would appear unlikely. Only those that meet certain preceding conditions could split, not every path that has diverged on an earlier point, I would think. I'm not sure if that's where you're getting hung up.

In the airplane scenario, just because it's easier to keep going with the same path of discussion for me, once the split occurs at the crash or not crash division, all those universes in which the plane did not crash continue on happily without any further bifurcations related to that event, and only those in which the plane crashes would then continue with bifurcations related to the events of the crash. You wouldn't get a scenario where the plane doesn't crash, lands safely on the ground, and all the passengers are inexplicably dead to balance out all the passengers surviving the fiery crash in another universe.

But, if I'm understanding Vanesch's explanation correctly, there are two more wrinkles here. First, it's not necessarily true that all these universes REALLY exist, just that it's a way of thinking about the mathematical probabilities and easier to consider they MIGHT exist (I'm not totally sure if I'm understanding him on this point or not). Second, we can't assume every outcome is an even probability. We might be playing with loaded dice. Does every time an outcome happens in a particular direction weight the probabilities of future events toward following a similar outcome?

I think we are living in one of those "Highly unlikely universes", Thinking about life itself and just for example, the evolution of a sperm and an ovum into a human being is more complex and unlikely that the plane crash scenario!
Say thanks to the anthropic principle!

Now the question i ask is, why i am experiencing this branch where i am writing here, and not another where i do something else?
This also brings a lot of questions about free will

 

[Evo]

I never mentioned good or bad decisions

I used the word 'decisions" in place of your "paths". Choosing a path is making a decision.

 

[Burnsys]

Of course, subjective experience can throw a wrench into all this with things like quantum immortality, but then the discussion ventures from science as we know it. If the outcome of an experiment cannot be objectively agreed upon, there's not much point in performing it.

That means your are not willing to pull the trigger?

 

[Art]

I used the word 'decisions" in place of your "paths". Choosing a path is making a decision.

It's the 'good' and 'bad' I referred to as irrelevent.

Read Vanesch's replies to my post. He understands my point and his replies may help clarify it for you.

 

[Evo]

It's the 'good' and 'bad' I referred to as irrelevent.

Read Vanesch's replies to my post. He understands my point and his replies may help clarify it for you.

I read his reply. He was responding to a different point.

I was responding to this post of yours

so why is it that when you look back over your life nearly all the paths you ended up on happened to represent the most likely? Also it follows that if the 'primary' you hogged all of the most likely paths your doubles were left to take the less likely paths so when they look back over their lives they would see a string of unlikely happenings.

Go back and read my response as it pertains to this statement of yours.

 

[Art]

I read his reply. He was responding to a different point.

I was responding to this post of yours

Go back and read my response as it pertains to this statement of yours.

Evo it doesn't! I'm talking about probabilities whereas you are talking about good and bad life choices. The two are a universe apart

 

[Moonbear]

Moonbear imagine you are walking down a road and it forks into 2, suddenly there are also 2 of you. One takes one turn and the other you takes the other. Next these 2 come to another set of forks so there are now 4 yous each on one of the new tracks. This continues on until there zillions of you.

Now at each junction there was a 50:50 chance which path the 'primary' you ended up on as you had no way of knowing which path represented the most likely (as you had no knowledge or say in the universe splitting) so why is it that when you look back over your life nearly all the paths you ended up on happened to represent the most likely? Also it follows that if the 'primary' you hogged all of the most likely paths your doubles were left to take the less likely paths so when they look back over their lives they would see a string of unlikely happenings.

What makes you assume any path was more "likely" than the others, though? That's what I don't understand about what you're saying. If I went right instead of left, why would I look back from either and think there was anything "unlikely" or "likely" about what path I wound up on, as long as the two options were possible? It's not like one path had a brick wall in the middle of it, and I somehow wound up on the other side of the wall without having ever climbed it.

Sticking with life's choices as the example, I'm not even sure I ever have taken the "likely" path. It certainly hasn't been my predicted path. I'd have to guess that somewhere in another universe, there's one of me who is an M.D., married, 1 kid, living in a big house with a dog as a pet, a housekeeper, and comfortably wealthy living off inheritance money, because those are the paths I didn't take along the way when various opportunities were presented. There's nothing more or less likely about that had I wound up on that path rather than the one I did end up choosing. In fact, with my background, this analogy would also mean there's a universe with one of me who never went to college, and took over my dad's carpentry business right out of high school. Had I wound up on that path, again, how would I look back and think there was anything less likely about it than the path I wound up on? How would I know this path was ever a possibility to even realize I missed something at one of those turns? I think you're also assuming an awareness of all the possible outcomes at every step of the decision/bifurcation process that doesn't need to exist. I guess for the mathematical model to work, there needs to be knowledge of the decision points on behalf the mathematician (which makes it pretty untestable if you can't know all the decision points), but that doesn't mean someone making those decisions is aware they had the choice to take a path other than the one they took. How often, when you're walking somewhere, do you stop and think, "Gee, I could have turned left there instead of right...why didn't I, and how will that impact my entire future? What if I missed some golden opportunity that was just waiting for me to the left and it's now too late?"

 

[SpaceTiger]

Now at each junction there was a 50:50 chance which path the 'primary' you ended up on as you had no way of knowing which path represented the most likely (as you had no knowledge or say in the universe splitting)

How is this applicable? The entire purpose of quantum theory is to determine probabilities for individual outcomes. MWI simply provides a possible explanation for why we can't make those probabilities into certainties.

 

[Evo]

Evo it doesn't! I'm talking about probabilities whereas you are talking about good and bad life choices. The two are a universe apart

No, I am asking you why you are making these assumptions. You've made the same assumptions in several posts.

Moonbear imagine you are walking down a road and it forks into 2, suddenly there are also 2 of you. One takes one turn and the other you takes the other. Next these 2 come to another set of forks so there are now 4 yous each on one of the new tracks. This continues on until there zillions of you.

Now at each junction there was a 50:50 chance which path the 'primary' you ended up on as you had no way of knowing which path represented the most likely (as you had no knowledge or say in the universe splitting) so why is it that when you look back over your life nearly all the paths you ended up on happened to represent the most likely? Also it follows that if the 'primary' you hogged all of the most likely paths your doubles were left to take the less likely paths so when they look back over their lives they would see a string of unlikely happenings.

Why do you keep making this assumption? I was (and still am) hoping you will explain why you think this. Looking back at my life, I don't see that "nearly all the paths I ended up on happened to represent the most likely". I think a lot of people would agree that they ended up on some very unlikely paths. I certainly did. I never would have chosen this career, I got sucked into it, and I will never forgive myself for not going against my father and going into science which was my passion for all of my life.

 

[EnumaElish]

I will never forgive myself for not going against my father and going into science which was my passion for all of my life.

You don't need to let it go; just make it Evo's problem in a parallel universe.

 

[Art]

I think you are taking my metaphor too literally. It is not about life choices it is about pure chance such as whether or not you get struck by lightning during a storm. To keep it simple there are 2 possibilities either you are or you are not. The most LIKELY outcome is you are not but because there is a very slight chance you are the universe needs to split to cover that eventuality and so your double is struck by lightning. Throughout your life there are many similar instances where the universe would split to cover equally unbalanced events and invariably it is your double who suffers the UNLIKELY consequence whereas if the path after the split was truly random in a 2 choice scenario 50% of the time it should be you.

The path = the passage of time
The forks = splits in the universe