Many worlds

[Butters]

I just have a question relating to the many-worlds theory. The idea that all possibilities actually happen makes a certain kind of sense, but I was wondering how small exactly the definition of a possibility is supposed to go?

 

The idea that movies enjoy depicting is that it is some 'significant event' that 'creates a new universe' seems the silliest of all, as it would seem to imply that the universe somehow makes a judgement call on what it considers significant, especially in relation to humans. Fine, that's movies. They don't have to make too much sense.

 

But what about smaller scale things? What if I move my arm slightly whilst watching television one night? Now what if I move my arm but the person next to me doesn't? Or we both don't, but the guy in the house next door does? And then we take into account everyone on the planet and where their arms are and so on. That's one planet down, now how many more do we have to consider? Then of course the smaller interactions of forces on objects and so on.

 

And of course, what about the location of individual molecules in my body? The infinite minor variations that might occur within me moving my arm, and precisely how far I move it, and then every combination of these combined with every other event in the universe.

 

Then within those molecules, does it matter what the precise position of the atoms in them is? And even then, how small do the measurements have to be before they become insignificant and don't require an entire universe to accomodate the endless permutations of all these near-infinite variables?

 

Is there a measurement that is as fundamentally small as things can get? Something beyond the planck length scale or whatever else we have decided is very very small.

 

This is reductio ad absurdum, I realise, and of course it is possible that the answer is simply this.

 

'Yes. All these things matter and are measured infinitely and there are an infinite number of universes because of this. That's what infinite means, you idiot!'

 

I also have a friend who argues that everything in the universe is measurable, right down to human motivations and actions, and so the point is moot. These things that seem to be different possibilities are in fact nothing of the sort. It's a sort of clockwork universe idea where free will is an illusion and so the only different possibilities would be from things outside of the universe that affect it. This concept may or may not be meaningless!

 

I am curious as to what the general consensus on this is?

[between3and26characterslon]

I was thinking something similar the other day and something hit me. If there are infinite universes, or in the sense you're asking, infinite futures are there also an infinite number of histories/pasts?

 

I arrived at the conclusion that if there is only one past there can only be one future. I don't like the idea that there is only one future, it means I have no choice in anything as everything is predetermined.

 

I much prefer the idea there are infinite futures but this means there are infinite pasts as well. I find this notion bizarre as I only remember one past.

 

Here's my logic.

 

There is more than one possibility what might happen in 5 mins time

There is aslo more than one possibility what might happen in 10 mins time

 

If in 10 mins time I look back 5 mins ago there must have been more than one possible future but as it is now in the past there must be more than one possible past.

 

It's a strange world (universe) we live in.

[Butters]

Well remembering only one past isn't really an argument against the theory, as you are just one possibility and lived only one possible version of events. There is an infinite number of 'you' that remember only their specific and slightly different past.

 

I have to assume that all these universes are not simply brought into existence as the events happen. There must simply be an inifnite number of universes where everything is playing out simultaneously. If the possibilities are infinite then you can't 'create' a new universe by making a decision because it must already exist. Despite what small children seem to think, there is no infinity plus one!

 

Also of interest, are things like the universal constants actually constants? Is it physically possible for these things to be different? Are there possible universes where matter cannot bond together to form planets and stars?

[Gear.0]

But if there were already an infinite number of universes that sort of defeats the purpose of the many worlds theory.

I don't think the idea of many worlds came about simply because there are so many possibilities that we think there has to be a universe for all of them... that doesn't really make any logical sense.

 

The reason for the idea I think, is to correct an obvious paradox that arises from the Copenhagen interpretation of the wavefunction collapse. If we are observing a particles spin, say, up or down. It has a 50% chance of being either. Now, say I measure spin up, then the wavefunction has collapsed and the particle is now in a definite state of spin up. However, if you are completely isolated from me and are unaware of my measurement, then the particle should still be in a superposition of 50%-50% spin up and spin down...

But how can this be? I know for certain that when you measure the particle you will find it to be spin up because I know it is spin up, but the wavefunction is still a superposition to you. So in order to preserve the notion that the system really is undetermined until you measure it requires that there can be different realities.

 

In this hypothetical scenario you and I are completely isolated from each other, so even if you do measure spin down, then you will be in the world in which I measured spin down at the beginning, and if you measure spin up then you will be in the world in which I measured spin up.

 

Also I think that is how the idea is introduced, as a branching set of worlds that continually grows.

Edited September 19, 2010 by Gear.0

[Butters]

Okay, but doesn't that get into the whole thing about what actually constitutes an observer? As in, when does the world branch off? Does it require a specific event involving observers to do so, and if that is the case, then doesn't that imply that the universe has some sort of bias towards consciousness? That would be a very profound thing to prove.

 

It just seems like an overly complicated concept to explain something that we find difficult to comprehend. It's not a very neat explanation. Which of course proves nothing either way. My instinctive sense of the nature of the universe is not a very strong authority for anything!

[michel123456]

Okay, but doesn't that get into the whole thing about what actually constitutes an observer? As in, when does the world branch off? Does it require a specific event involving observers to do so, and if that is the case, then doesn't that imply that the universe has some sort of bias towards consciousness? That would be a very profound thing to prove.

 

It just seems like an overly complicated concept to explain something that we find difficult to comprehend. It's not a very neat explanation. Which of course proves nothing either way. My instinctive sense of the nature of the universe is not a very strong authority for anything!

 

i like your posts Butters.

For me, it's simple, the Many Worlds Interpretation is wrong.

 

As for the numbers of future, there is only one. But you can chose that one from an infinity. In a large part, you can decide what your future will be. The Sun cannot do that.

[Butters]

The reason for the idea I think, is to correct an obvious paradox that arises from the Copenhagen interpretation of the wavefunction collapse. If we are observing a particles spin, say, up or down. It has a 50% chance of being either. Now, say I measure spin up, then the wavefunction has collapsed and the particle is now in a definite state of spin up. However, if you are completely isolated from me and are unaware of my measurement, then the particle should still be in a superposition of 50%-50% spin up and spin down...

But how can this be? I know for certain that when you measure the particle you will find it to be spin up because I know it is spin up, but the wavefunction is still a superposition to you. So in order to preserve the notion that the system really is undetermined until you measure it requires that there can be different realities.

 

But solving this problem by contemplating many different realities seems like the long way around. It would make more sense to me to assume that time is not linear and that the measurement is already determined. I am going to measure it and get the same result as you in the future. It has already happened, it's just that my linear perception of time hasn't perceived that measurement yet.

 

It may sound silly and a bit sci-fi with no real evidence to back it up, but to my mind it is at least as plausible as multiple realities, and far simpler in many ways.

 

Of course it also undermines any sense of free will if all time exists at once and has already happened, so perhaps that's why it's not as palatable as the many worlds theory...

[Gear.0]

But solving this problem by contemplating many different realities seems like the long way around. It would make more sense to me to assume that time is not linear and that the measurement is already determined. I am going to measure it and get the same result as you in the future. It has already happened, it's just that my linear perception of time hasn't perceived that measurement yet.

 

It may sound silly and a bit sci-fi with no real evidence to back it up, but to my mind it is at least as plausible as multiple realities, and far simpler in many ways.

 

Of course it also undermines any sense of free will if all time exists at once and has already happened, so perhaps that's why it's not as palatable as the many worlds theory...

 

Some theories are widely accepted, almost as if you can take them as fact. The many worlds theory, as far as I know, is definitely not one of them. It's just one possibility, and as long as we have some, no matter how small, reason to think it is a valid possibility then it would be foolish to dismiss it.

But, as you say, if all realities happened all at once but were independent of each other, then as I have already shown there is no need for that.. Why can't there just be one? What I was showing in my previous post is that there is actually a logical progression of thought that leads to the many worlds theory as a solution to something, and the many worlds are not independent of each other, so if the theory is right, then it plays a direct role in our reality.

The idea you are trying to use, where all realities exist simultaneously should have no effect on our reality whatsoever whether it is right or wrong, and as such it is probably impossible for us to ever know, which is why it is not really a useful theory.

Edited September 21, 2010 by Gear.0

[kaycee]

i agree with michel123456, i do like your posts butter.

personally, id rather much like to agree with the copenhagen interpretation, though, as Gear.0 said, it would be a ridiculous theory to try to prove. The idea that all realities exist simultaneously, with objects in superposition and only ever being forced to move due to observation is more valid than the many worlds theory which has been greatly contradicted by the quantum-suicide theory!

[padren]

I always thought superpositions were the latticework through which the varying probabilistic qualities of the Universe are interconnected.

 

When you take a measurement you find out what side you are on, and you know that the other value is on the other side, but there is no way to interact with that other side or predict which side you are on beforehand. The intersections are not based on "decisions" but quantum superpositions, so our "choices" aren't what it's about.

 

 

 

Also: They have determine that the Universal Constants do vary in this universe, and appear to distort the farther away from our galaxy you get. Some of the deepest Hubble imagery has provided data that describes how those constants vary, though they are as good as constant for the purpose of almost everything within our ability to observe.

Edited September 30, 2010 by padren

[swansont]

 

Also: They have determine that the Universal Constants do vary in this universe, and appear to distort the farther away from our galaxy you get. Some of the deepest Hubble imagery has provided data that describes how those constants vary, though they are as good as constant for the purpose of almost everything within our ability to observe.

 

IIRC, it's one research group which has presented such results. Nobody else has been able to replicate them, so "It has been determined " is too strong a statement, IMO. (The recent results were not Hubble, they were Keck and VLT.)