RoR: Forum

I want to point out that many in the physics community are taking Ashfar's experiment with a grain of salt, at least until Ashfar does a slowed-down, photon by photon version of his experiment, which should happen this year (at Rowan University in New Jersey). Also, it would be interesting to see what would happen if he repeated the experiment with electrons, since they have also been know to show Bohr's "complementarity."

So...stay tuned everyone!

Tessa

Post 1

Wednesday, August 4, 2004 - 8:27pm

The many-worlds interpretation of QM is a fully Objective (realist) and deterministic metaphysics. Many-worlds says that reality consists of a giant multiverse of 'alternative universes' where every possible quantum outcome is realized. Human observers are only directly aware of one particular branch of the multiverse. So according to this interpretation the wave function is a complete description of reality (the wave function never 'collapses') and the evolution of the wave function is also completely deterministic. See 'The Fabric of Reality' by David Deutsch for a detailed defense. I would say that many-worlds is in fact the only interpretation fully consistent with an objective metaphysics and epistemology.

This latest experiment if confined would provide a welcome refutation of the mystical/subjectivist Copenhagen Interpretation. But I do not believe that it refutes many-worlds.

(Edited by Marc Geddes on 8/04, 8:29pm)

(Edited by Marc Geddes on 8/04, 8:30pm)

Post 2

Wednesday, August 4, 2004 - 9:06pm

Hi Marc,

Arguments of validity notwithstanding, we have no reason to believe that these "many universes" exist when we cannot observe any of the other universes-- to me the Many World's Theory seems nothing more than a trick of reifying probability. Hence, if given a choice between Many Worlds and the Transactional Interpretation, Occam's Razor and the non-falisfiability of all of the other "universes" would support the Transactional Interpretation.

Post 3

Wednesday, August 4, 2004 - 9:40pm

Adam,
I would like to know what you think of the current versions of Bohm's theory of "quantum potentiality". Most scientific realists accept that theory as the best way of combatting the copenhagen interpretation. Yet you apparently think it is inadequte, since you support the "transactional" interpretation. I would like to hear your comments on this.

-----------------------------Tom Blackstone

http://tomsphilosophy.tripod.com

Post 4

Wednesday, August 4, 2004 - 9:48pm

Hi Marc,

Arguments of validity notwithstanding, we have no reason to believe that these "many universes" exist when we cannot observe any of the other universes-- to me the Many World's Theory seems nothing more than a trick of reifying probability. Hence, if given a choice between Many Worlds and the Transactional Interpretation, Occam's Razor and the non-falisfiability of all of the other "universes" would support the Transactional Interpretation.

There is indirect evidence for Many-Worlds. The theory of QM has been tested and found to correspond to things that scientists can directly observe. Since QM is giving correct predictions about observables, this is reason to trust it on the non-Observables as well. If you take a realist picture of reality and you assume that QM is the right theory, the maths has to be referring to things that actually exist in reality. And the simplest intrepation of the maths is that its referring to multiple alternative universes corresponding to all possible qauntum outcomes. That is the 'picture of reality' the maths is giving us.

The Transactional Interpretation is intriguing, and worth looking into, but the advantage of Many-Worlds is that it helps to clear up philosophical paradoxs about reasoning and free-will. For instance the phrase 'I could have done something different this morning' (counter-factual) is actually philosophically incoherent without the existence of an actual concrete place where an alternative version of you did do something different. Many-Worlds neatly accounts for this by saying that that alternative version of you really does exist in the other quantum branch. Many-Worlds also clears up philosophical epistemological problems. According to Bayesian/Popperian reasoning, we have to consider multiple possibilities to which we assign different probabilities. But to what could these probabilities be referring? For instance what sense does it make to say that George Bush has a 55% chance of re-election, unless the exact same election was 're-run' many times? Many-Worlds has a simple answer. The probablities are referring to the frequency of events in all the alternative universe.

A fully consistent metaphysics, epistemology, ethics and politics all fits together like a dazzling jig-saw puzzle. Only the philosophy of Transhumanism provides this fully consistent framework..

Post 5

Wednesday, August 4, 2004 - 10:55pm

Hi Marc,

There is indirect evidence for Many-Worlds.

Which experiments provide this evidence?

The theory of QM has been tested and found to correspond to things that scientists can directly observe.

I agree, the mathematics yield results consistent with actual events.

Since QM is giving correct predictions about observables, this is reason to trust it on the non-Observables as well.

Non-observable phenomena are non-falsifiable, and so we cannot speak to them scientifically.

If you take a realist picture of reality and you assume that QM is the right theory, the maths has to be referring to things that actually exist in reality. And the simplest interpretation of the maths is that its referring to multiple alternative universes corresponding to all possible qauntum outcomes. That is the 'picture of reality' the maths is giving us.

One must never mistake the map for the territory. Jsut beacuse a mathematical theory "suggests" something, it doesn't mean that something really exists. Remember that jass about the aether in the early 20th century to answer the question: "If light is a wave, what's doing the waving?" The question shouldn't have been posed in the first place. Just because light behaves like a wave doesn't mean it really is one.

The Transactional Interpretation is intriguing, and worth looking into, but the advantage of Many-Worlds is that it helps to clear up philosophical paradoxs about reasoning and free-will. For instance the phrase 'I could have done something different this morning' (counter-factual) is actually philosophically incoherent without the existence of an actual concrete place where an alternative version of you did do something different. Many-Worlds neatly accounts for this by saying that that alternative version of you really does exist in the other quantum branch.

What if the meaning of the statement above is that I simply reason that if I had acted differently than I had, my experience suggests that another causal chain of events would have happened, resulting in a different outcome? Seems simpler than postulating a colossal number of universes which we cannot even verify exist.

Many-Worlds also clears up philosophical epistemological problems. According to Bayesian/Popperian reasoning, we have to consider multiple possibilities to which we assign different probabilities. But to what could these probabilities be referring? For instance what sense does it make to say that George Bush has a 55% chance of re-election, unless the exact same election was 're-run' many times? Many-Worlds has a simple answer. The probablities are referring to the frequency of events in all the alternative universe.

You seem to think that every future event can be assigned some probability. Take, for instance, your example: what, indeed, do you mean by "Bush had a 55% chance of winning?" How did you get this figure? I don't think one can claim such a statistic with any honesty. The fact is, we came to the idea of "probability" by running experiments and noting the frequency of the outcomes. You can't apply a probabilistic approach to anything that isn't ultimately based upon controlled, repeated observation.

Nate T.

Post 6

Wednesday, August 4, 2004 - 11:23pm

Non-observable phenomena are non-falsifiable, and so we cannot speak to them scientifically.

Here is where I have to disagree with you. Recall what I said about epistemology in the other thread. Scientists formulate rational hypotheses and then judge them on the basis of their explanatory power. 'explanatory power' means how well a hypotheses explains reality - there can be many critera for this (Examples: Coherence, Consistency with other knowledge, ability to make new predictions, Occam's razor and many more). The hypotheses with the most explanatory power is taken to be the one most likely to be true. If this hypothesis uses Non-obervable phenomena, then there is sufficient indirect evidence for believing that these non-observables exist. There is no need to directly observe something to prove its existence. Direct observations are only one kind of evidence contributing to explanatory power. I gave others (coherence etc etc). Scientists actually believe in all kinds of non-observables. Examples: Dark energy, Quarks, Space-Time manifold, Magnetic field etc etc.

One must never mistake the map for the territory. Jsut beacuse a mathematical theory "suggests" something, it doesn't mean that something really exists. Remember that jass about the aether in the early 20th century to answer the question: "If light is a wave, what's doing the waving?" The question shouldn't have been posed in the first place. Just because light behaves like a wave doesn't mean it really is one.

If a mathematical theory suggests something, true that doesn't prove with certainty that it exists, but it does provide evidence that a non-observable has a high probablity of existing. The criterea for judging hypotheses doesn't have to be physical. See what I said above. There are numerous examples of mathematical theories suggesting non-observable things which much later turned out to be observable after all. Much more often than not the maths theory turns out to right. A famous example of this is the theory of Atoms. No one could observe them until very recently and for a long time philosophers argued that Atoms didn't exist because they were just 'theory'. But now we can actually directly observe atoms. So the maths was right all along. A realist picture of reality demands that we believe what our best theories are telling us. Just because we can't directly observe the alternative universes right now, doesn't mean that science won't find out how to direct;y observe them at some point in the future. Again, an Objectivist metaphysics demands that we accept our best theories as providing an accurate picture of reality until proven otherwise.

What if the meaning of the statement above is that I simply reason that if I had acted differently than I had, my experience suggests that another causal chain of events would have happened, resulting in a different outcome? Seems simpler than postulating a colossal number of universes which we cannot even verify exist.

Your statement: 'if I had acted differently than I had, my experience suggests that another causal chain of events would have happened, resulting in a different outcome?' is meaningless if only one universe exists. If only one timeline exists there was only one possible chain of events.

You seem to think that every future event can be assigned some probability. Take, for instance, your example: what, indeed, do you mean by "Bush had a 55% chance of winning?" How did you get this figure? I don't think one can claim such a statistic with any honesty. The fact is, we came to the idea of "probability" by running experiments and noting the frequency of the outcomes. You can't apply a probabilistic approach to anything that isn't ultimately based upon controlled, repeated observation.

Nate T.

The problem with probabilities that you've outlined was exactly my point! Indeed you can't apply the probablitistic approach to anything that doesn't involve repeated frequencies of events. That's a reason for believing in Many-Worlds, because with multiple alternative universes, you can then say (for instance) that Bush wins with a frequency of 55% (55% of all the universes have Bush winning). The fact of the matter is that people do assign probablities to events in the real-world. The 55% figure for a Bush win I gave you actually comes from the odds offered by current 'futures markets' (where people place bets on various events). Check out this link:

http://www.mises.org/fullstory.aspx?control=1575

There is no way to make sense of these probabilities without the Many-Worlds theory.

(Edited by Marc Geddes on 8/04, 11:28pm)

Post 7

Thursday, August 5, 2004 - 8:19am

Hi Marc,

Recall what I said about epistemology in the other thread. Scientists formulate rational hypotheses and then judge them on the basis of their explanatory power. 'explanatory power' means how well a hypotheses explains reality - there can be many critera for this.
Examples: Coherence, Consistency with other knowledge, ability to make new predictions, Occam's razor and many more). The hypotheses with the most explanatory power is taken to be the one most likely to be true. If this hypothesis uses Non-obervable phenomena, then there is sufficient indirect evidence for believing that these non-observables exist. There is no need to directly observe something to prove its existence.

First and foremost, a theory must fit the facts. We're not talking about a table of numbers here, were talking about a theory, some mathematical system with a unifying aspect (i.e., all data fit can be predicted by some mathematical scheme). If such a theory does not fit the facts, it's wrong. Period. Internal consistency and consistency with other knowledge are great and all, but it is meaningless if it isn't in accordance with reality. Only after you have a collection of theories which fit the facts more or less equally do you begin to consider other criteria.

Direct observations are only one kind of evidence contributing to explanatory power. I gave others (coherence etc etc). Scientists actually believe in all kinds of non-observables. Examples: Dark energy, Quarks, Space-Time manifold, Magnetic field etc etc.

Just because some scientists believe in some phenomena does not imply its existence. This is an appeal to authority. Again, the aether was postulated because scientists reified the "light as wave" idea and needed a medium to make this picture make sense. Michaelson-Morley found no evidence of the aether and so it was rightly rejected. Turns out the Theory of Relativity explained relativistic contractions with fewer assumptions anyway.

Some specific points: Dark matter is just like the aether was-- we're postulating a mystery substance because the galaxies don't quite behave like they should according to our current theories. Some scientists think that our problems will be solved by sweeping our problems away under the banner of "Dark Matter;" it doesn't mean they are justified to do so. We have indirect evidence for quarks (particle jets). Space time manifolds and magnetic fields are mathematical devices used to make predictions, nothing more.

If a mathematical theory suggests something, true that doesn't prove with certainty that it exists, but it does provide evidence that a non-observable has a high probablity of existing.

No. Just because you look at the equations governing sounds waves and the equations governing light and you note that there is a superficial similarity between them, you do not conclude that "Light is a wave." That was the problem that resulted in postulating the unobservable aether.

The criterea for judging hypotheses doesn't have to be physical. See what I said above. There are numerous examples of mathematical theories suggesting non-observable things which much later turned out to be observable after all.

Yes, but they "turned out to be observable" because we observed them, right? That means they weren't really unobservable, just unobserved.

Much more often than not the maths theory turns out to right. A famous example of this is the theory of Atoms. No one could observe them until very recently and for a long time philosophers argued that Atoms didn't exist because they were just 'theory'. But now we can actually directly observe atoms. So the maths was right all along.

Ancient astronomers weren't right about epicycles, early 20th century scientists weren't right about the aether, etc. Hundreds of unified theories of physics have been published, and not one of them has been found to be acceptable.

A realist picture of reality demands that we believe what our best theories are telling us. Just because we can't directly observe the alternative universes right now, doesn't mean that science won't find out how to directly observe them at some point in the future. Again, an Objectivist metaphysics demands that we accept our best theories as providing an accurate picture of reality until proven otherwise.

Agreed. However, until I hear of an experiment which purports to show the existence of these alternate universes, I consider it an unlikely proposal, at best.

Your statement: 'if I had acted differently than I had, my experience suggests that another causal chain of events would have happened, resulting in a different outcome?' is meaningless if only one universe exists. If only one timeline exists there was only one possible chain of events.

I have a memory. I have the ability to reason. I have observed that my actions begin causal effects, some of which I can predict. Hence, I can reason that in the past, had I acted differently, the state of things now would have been different. There being only one chain of events does not rule out reasoning whether that chain could have been different.

The problem with probabilities that you've outlined was exactly my point! Indeed you can't apply the probablitistic approach to anything that doesn't involve repeated frequencies of events. That's a reason for believing in Many-Worlds, because with multiple alternative universes, you can then say (for instance) that Bush wins with a frequency of 55% (55% of all the universes have Bush winning).

My problem was that you are taking the concept of a probability and improperly applying it to events which have no reason to be associated with a probability. You then rightly reason that in order for an event to have a probability associated with it, it must have been the subject of repeated, controlled observation, and from there you postulate the existence of alternate universes to reify these other hypothetical scenarios into a bunch of "hypothetical scenario universes" which literally exist somewhere. It would seem that these "alternate universes" are a product of your desire to assign every event a probability, not the other way around.

The fact of the matter is that people do assign probablities to events in the real-world. The 55% figure for a Bush win I gave you actually comes from the odds offered by current 'futures markets' (where people place bets on various events).

A bandwagon appeal. Just because a group of people would like to bet on the election does not mean that their prediction has any special weight. Even if it did, somehow, there would be no way to know it, since the 2004 Bush/Kerry election is an event which will happen only once, so we have no way to know whether this "futures market" poll of yours is valid or not.

There is no way to make sense of these probabilities without the Many-Worlds theory.

I agree. That's why you shouldn't claim those probabilities.

Nate T.

Post 8

Thursday, August 5, 2004 - 6:12am

There is no way to make sense of these probabilities without the Many-Worlds theory.

I'm afraid that I don't find the claim that it makes no epistemological sense to talk about a �55% chance” without assuming infinite universes convincing . You might as well argue that you can't talk about a �fork� (as opposed to a lump of metal bent into a particular shape) without assuming a parallel �universe of Forms� in which this alleged �fork� exists.

There are plenty of ways to give probabilities an exact epistemological meaning, even in cases where you aren't able to do explicit repeated experimentation. Just a few examples I can think of immediately:

In 55 out of 100 contexts similar to the present circumstance, this was the outcome. (The estimate of the exact probability here varies based upon the precise criterion of �similar� chosen by a specific estimator.)
55 out of 100 people (with some criterion of authority) believe this will be the outcome.
If the situation were hypothetically allowed to unfold 100 times, this would be the outcome 55 times.

Post 9

Thursday, August 5, 2004 - 9:41am

Hi Nature,

I wanted to address your indirect ways of giving probability an exact meaning.

In 55 out of 100 contexts similar to the present circumstance, this was the outcome. (The estimate of the exact probability here varies based upon the precise criterion of �similar� chosen by a specific estimator.)

This is the method of choice for me. I contend it is the only such method of assigning a probability to an event (since even the most controlled experiment cannot hold court in a totally closed system).

55 out of 100 people (with some criterion of authority) believe this will be the outcome.

I don't necessarily agree with this one. For instance, suppose you have a biased polling, or the experts themselves don't have the evidence to judge the outcome and they are merely guessing? For example, I wonder how many experts of the time thought that Columbus would have reached India sailing west across the Atlantic?

If the situation were hypothetically allowed to unfold 100 times, this would be the outcome 55 times.

Reasoning through a repeated experiment wouldn't really help to decide exactly how many events have a particular outcome. Humans tend to be really bad at giving random behavior (e.g., if you ask a person to pick a number between 1 and 10, they are not all equally likely to be chosen). Better to stick with the experiments themselves.

Nate T.

Post 10

Thursday, August 5, 2004 - 7:55pm

I think I'm going to jump into this debate on Nate's side. The feature of the Many Worlds interpretation that I find hard to accept is how, when there are an infinite number of universes (in which an infinite number of infinitely differing situations play out...), we have memories of only one. Our memories may not always be objective evidence since memories can be falsely reconstructed through suggestion or buried because of trauma, but nevertheless our memories are evidence of one, and only one, universe. My question (to Mark) is basically this: by what mechanism does our consciousness follow one and only one path through the multitude of universes described by the Many Worlds interpretation? It seems to me that the Many Worlds interpretation just skirts around the collapse of the wave function by introducing a collapse of the human consciousness.

Tessa

Post 11

Friday, August 6, 2004 - 12:59am

First and foremost, a theory must fit the facts. We're not talking about a table of numbers here, were talking about a theory, some mathematical system with a unifying aspect (i.e., all data fit can be predicted by some mathematical scheme). If such a theory does not fit the facts, it's wrong. Period. Internal consistency and consistency with other knowledge are great and all, but it is meaningless if it isn't in accordance with reality. Only after you have a collection of theories which fit the facts more or less equally do you begin to consider other criteria.

Well yes I agree. A theory has to fit the facts. But my point was that there are also a range of abstract critera for judging the merits of theories quite aside from observation. Things like interal consistency, consistency with other knowledge etc are useful for helping to determine which theories are more likely to conform to reality. In mathematics for example, none of the critera for determining facts depend on physical observation. Yet many agree that mathematics is science which is making genuine discoveries none the less.

Just because some scientists believe in some phenomena does not imply its existence. This is an appeal to authority. Again, the aether was postulated because scientists reified the "light as wave" idea and needed a medium to make this picture make sense. Michaelson-Morley found no evidence of the aether and so it was rightly rejected. Turns out the Theory of Relativity explained relativistic contractions with fewer assumptions anyway.

Well of course scientists are not always right. But a rational peson has to go with the best available theory.

Some specific points: Dark matter is just like the aether was-- we're postulating a mystery substance because the galaxies don't quite behave like they should according to our current theories. Some scientists think that our problems will be solved by sweeping our problems away under the banner of "Dark Matter;" it doesn't mean they are justified to do so. We have indirect evidence for quarks (particle jets). Space time manifolds and magnetic fields are mathematical devices used to make predictions, nothing more.

There is much more evidence for dark energy than there ever was for the aether. You have also conceded that indirect evidence is sufficient to postulate the existence of something is currently not directly observabel (quarks).

I have to disagree with you when you say: 'Space time manifolds and magnetic fields are mathematical devices used to make predictions, nothing more'. This is logical positivism.
Ask yourself if it is really the case that scientists are just people trying to come up with mathematical devices for making predictions. I'm sure that if you asked scientists, that's not really what they'd think they're actually doing. Rather they'd be more likely to say that they're trying to explain reality.

If you adopt an Objectivist metaphysics (as I do) you have to agree that:

(a) An objective reality really does exist
(b) Reason is capable of modelling it (although perhaps not with certainty)
(c) A rational person has accept the best available theory as providing an actual picture of this reality until proven otherwise.

Saying that: 'Space time manifolds and magnetic fields are nothing more than mathematical devices' is actually to deny Objective reality and/or rationally. Space-time manifolds and magnetic fields are the best available explanations of aspects of reality that were in need of explanation. We have to accept these thinbgs as being part of an actually existing objective reality until proven otherwise. Of course we will not always be right (some theories will turn out to be wrong) but this doesn't mean we should deny objective reality or rationally.

Yes, but they "turned out to be observable" because we observed them, right? That means they weren't really unobservable, just unobserved.

We don't know what will turn out to be observable. Therefore we shouldn't try to deny the existence of something just because it's currently unobservable wouldn't you agree?

Ancient astronomers weren't right about epicycles, early 20th century scientists weren't right about the aether, etc. Hundreds of unified theories of physics have been published, and not one of them has been found to be acceptable.

Of course there is no reason for believing every crack-pot theory that comes along. We can apply a range of critera (such as Occam's razor, consistency etc) to judge its worth. But if a theory seems to be better than all other theories in the context something that we are trying to explain, then we should accept it as providing a true and accurate picture of reality until proven otherwise.

Agreed. However, until I hear of an experiment which purports to show the existence of these alternate universes, I consider it an unlikely proposal, at best.

In the absence of a direct observational test, we can deploy some of the other critera mentioned to judge the merit of the Many-Worlds-Theory. The fact is: this interpretation can explain a range of scientific puzzles. I mentioned two of them: Free Will and the Use of Probabilities. Apart from this, the equations of QM have been tested and found to make accurate predictions. QM is our best available theory. Therefore a rational person who believes in an objective metaphysics has to accept that the maths is actually referring to things in concrete reality until proven otherwise. And the maths is describing multiple alternative outcomes which co-exist. The simplest picture which fits the maths is that multiple alternative universes really do exist.

I have a memory. I have the ability to reason. I have observed that my actions begin causal effects, some of which I can predict. Hence, I can reason that in the past, had I acted differently, the state of things now would have been different. There being only one chain of events does not rule out reasoning whether that chain could have been different.

Belief in an Objective metaphysics entails a belief in determinism. An Objective picture of reality describes space-time as eternal; Past, present and future are all 'already there'. If Many-Worlds is not true and if you demand an Objectivist metaphysics, then there is ony one time-line, everything going on your brain had deterministic causes and your statement: 'had I acted differently' is incoherent. It was logically impossible for you to act differently according to this picture.

The only way to save free will whilst at the same time holding on to an Objectivist metaphysics (with complete causality and determinism) is to postulate the existence of multiple alternative universes, corresponding to the range of possible outcomes. Only then is the statement: 'had I acted differently' coherent.

My problem was that you are taking the concept of a probability and improperly applying it to events which have no reason to be associated with a probability. You then rightly reason that in order for an event to have a probability associated with it, it must have been the subject of repeated, controlled observation, and from there you postulate the existence of alternate universes to reify these other hypothetical scenarios into a bunch of "hypothetical scenario universes" which literally exist somewhere. It would seem that these "alternate universes" are a product of your desire to assign every event a probability, not the other way around.

No I am observing how people actually go about reasoning in their daily lives and noting that either consciously or unconsciously they are assigning probabilities to possible events all the time. You can't reason without this. People have varying degrees of confidence about things, and whether they know it or not they are assigning probabilities to things based on their degree of confidence. Here are some conversations I overheard today: 'It's likely that it's going to rain today', 'What are the chances of Kerry being elected', etc. I then note that (as you correctly pointed out) these probabilities don't make sense without the concept of repeated frequencies, which requires Multiple Universes to exist. So Many-Worlds helps to explain this epistemology puzzle.

A bandwagon appeal. Just because a group of people would like to bet on the election does not mean that their prediction has any special weight. Even if it did, somehow, there would be no way to know it, since the 2004 Bush/Kerry election is an event which will happen only once, so we have no way to know whether this "futures market" poll of yours is valid or not.

People are assigning probablities to events all the time. Ever heard of futures markets? What about horse racing? These are very well defined markets which work. For instance when a book-maker offers odds of 10% that a horse will win a race, the horses which are assigned these probabilities do indeed win around 10% of the time.

I agree. That's why you shouldn't claim those probabilities.

Nate T.

I am pointing to the observed fact that in the real world people are assigning probablities to events all the time using probability theory, and probability theory has proven to be very useful to people. This requires explanation. Then I point out we cannot make sense of these probabilities without Many Worlds. No alternative theory explains why these probabilities work. Therefore this is strong evidence that Many Worlds is correct.

There are plenty of ways to give probabilities an exact epistemological meaning, even in cases where you aren't able to do explicit repeated experimentation. Just a few examples I can think of immediately:

In 55 out of 100 contexts similar to the present circumstance, this was the outcome. (The estimate of the exact probability here varies based upon the precise criterion of �similar�Echosen by a specific estimator.)

55 out of 100 people (with some criterion of authority) believe this will be the outcome.

If the situation were hypothetically allowed to unfold 100 times, this would be the outcome 55 times.

Nate did a good job of rebutting the middle interpretation. And see what I said above explaining why I don't think the first or third interpreations are coherent. Without Many-Worlds, if we demand an Objective metaphysics there is only one fully deterministic time-line. So phrases such as 'contexts similar to' and 'hypothetically' (referring to counterfactuals) cannot be made sense of. Either you have to give up Objective metaphysics or you have to accept Many-Worlds.

My question (to Mark) is basically this: by what mechanism does our consciousness follow one and only one path through the multitude of universes described by the Many Worlds interpretation? It seems to me that the Many Worlds interpretation just skirts around the collapse of the wave function by introducing a collapse of the human consciousness.

Tessa

You are right that it is a mystery why we are only consciouslly aware of one and only one path through the multitude of universes. This does require explanation. But it is a probalem for theories of consciousness, not Many Worlds as such.

(Edited by Marc Geddes on 8/06, 1:06am)

Post 12

Friday, August 6, 2004 - 6:46am

Hi Marc,

I'm about to leave town, so I'll address some of your points as briefly as I can.

There is much more evidence for dark energy than there ever was for the aether.

Like what?

You have also conceded that indirect evidence is sufficient to postulate the existence of something is currently not directly observabel (quarks).

Yeah, I do have to concede this one-- I had always assumed that quarks were genuine particles capable of being observed directly, but it turns out that they aren't. Therefore, thanks to our correspondence and some research on the history of their development (to make sense of a huge number of hadrons), I'm relegating them to the status of "mathematical device."

I have to disagree with you when you say: 'Space time manifolds and magnetic fields are mathematical devices used to make predictions, nothing more'. This is logical positivism.

Well, whoever they are or were, the logical positivists got that part right.

Ask yourself if it is really the case that scientists are just people trying to come up with mathematical devices for making predictions.

That's exactly what they're doing.

I'm sure that if you asked scientists, that's not really what they'd think they're actually doing. Rather they'd be more likely to say that they're trying to explain reality.

And they do that by coming with with a theory to explain the way some part of reality is. It may even help with their intuition to have an analogy to something in everyday life (i.e,., waves or strings or rubber sheets), but you cannot proceed from the intuition of the theory directly to new truths without verifying that such a leap is justified through experiment.

If you adopt an Objectivist metaphysics (as I do) you have to agree that:

(a) An objective reality really does exist
(b) Reason is capable of modelling it (although perhaps not with certainty)
(c) A rational person has accept the best available theory as providing an actual picture of this reality until proven otherwise.

Yep.

Saying that: 'Space time manifolds and magnetic fields are nothing more than mathematical devices' is actually to deny Objective reality and/or rationally.

How does this follow? As I've mentioned before, I'm not denying the existence of the consequences of a correct theory, just the existence of the analogies used to describe the theory.

Space-time manifolds and magnetic fields are the best available explanations of aspects of reality that were in need of explanation. We have to accept these things as being part of an actually existing objective reality until proven otherwise. Of course we will not always be right (some theories will turn out to be wrong) but this doesn't mean we should deny objective reality or rationally.

It's not that the "space-time manifold" is the explanation. It's that "the data, when plugged into a mathematical scheme involving a manifold (which you could think of as space and time) results in consequences which correspond to reality." You shouldn't assume that the magnetic field or any such thing exists merely because invoking it is useful for describing reality-- that's reification.

We don't know what will turn out to be observable. Therefore we shouldn't try to deny the existence of something just because it's currently unobservable wouldn't you agree?

Sorry if I haven't made my position clear here. If there is no evidence for the existence of a phenomenon one way or the other, we shouldn't necessarily rule out either its existence or nonexistence. However, if the thing is really unobservable in the sense that it can never be observed at all, then we should disregard the existential status of whatever-it-is, even if it may provide a useful way to describe reality (e.g., the "color" or "flavor" of subatomic particles.) A caveat: our ideas of what are observable change over time (we recently developed the technology to see the inner workings of the sun, for instance) However, the uncertain status of unobservability has nothing to do with whether the thing exists or not, merely whether it can be shown that it doesn't exist.

But if a theory seems to be better than all other theories in the context something that we are trying to explain, then we should accept it as providing a true and accurate picture of reality until proven otherwise.

And we mustn't forget that the picture is just that-- a picture.

Apart from this, the equations of QM have been tested and found to make accurate predictions. QM is our best available theory. Therefore a rational person who believes in an objective metaphysics has to accept that the maths is actually referring to things in concrete reality until proven otherwise. And the maths is describing multiple alternative outcomes which co-exist. The simplest picture which fits the maths is that multiple alternative universes really do exist.

More reification. See above.

Belief in an Objective metaphysics entails a belief in determinism.

This is false. consciousness is axiomatic and humans have volition. See the thread "Has Life Always Existed?" for an excellent summary of the position by Firehammer.

No I am observing how people actually go about reasoning in their daily lives and noting that either consciously or unconsciously they are assigning probabilities to possible events all the time. You can't reason without this. People have varying degrees of confidence about things, and whether they know it or not they are assigning probabilities to things based on their degree of confidence. Here are some conversations I overheard today: 'It's likely that it's going to rain today', 'What are the chances of Kerry being elected', etc. I then note that (as you correctly pointed out) these probabilities don't make sense without the concept of repeated frequencies, which requires Multiple Universes to exist. So Many-Worlds helps to explain this epistemology puzzle.

Once again, if you have observed that some event can be assigned probabilities, this does not mean that every event can be assigned a probability. Vague terms like "more likely than", "unlikely", etc., are merely ways to express hunches that if such events were ever controlled, the events would occur in respective frequencies. Without such a controlled experiment, to claim that "Event E has an X% chance of happening" is meaningless.

People are assigning probablities to events all the time. Ever heard of futures markets? What about horse racing? These are very well defined markets which work. For instance when a book-maker offers odds of 10% that a horse will win a race, the horses which are assigned these probabilities do indeed win around 10% of the time.

Once again, just because people are fond of vaguely assigning qualifiers like "likely" and "probably" doesn't mean that you can just quote a statistic without doing an experiment. Otherwise, the numbers are meaningless.

Are you saying that a bookie will assign a fixed probability that a given horse will win, regardless of the other horses in the race, the conditions of the field, the jockey riding the horse, and any other countless factors that determine the outcome of a race? Sounds bad for business to me, if true.

Not to mention, how do you know that the horse won 10% of the time? Were there repeated experiments (i.e,, multiple races) to confirm the bookie's probability? If so, his claim makes sense. If there was only one race, he has no basis in claiming that his quoted probability for "Horse H wins the race" is even close to correct, since the horse either wins or loses.

I am pointing to the observed fact that in the real world people are assigning probablities to events all the time using probability theory, and probability theory has proven to be very useful to people. This requires explanation. Then I point out we cannot make sense of these probabilities without Many Worlds. No alternative theory explains why these probabilities work. Therefore this is strong evidence that Many Worlds is correct.

Ditto on people claiming probabilities improperly. Of course probability is an important field, with tons of useful applications. But like all fields, it has its scope: all of the raw data about unbiased coins and probabilities must come from experiment-- you are allowed to assume that things are "likely", but you can't assign a number to that likelyhood with any degree of precision or accuracy.

Nate did a good job of rebutting the middle interpretation. And see what I said above explaining why I don't think the first or third interpreations are coherent. Without Many-Worlds, if we demand an Objective metaphysics there is only one fully deterministic time-line. So phrases such as 'contexts similar to' and 'hypothetically' (referring to counterfactuals) cannot be made sense of. Either you have to give up Objective metaphysics or you have to accept Many-Worlds.

One time line does not imply one deterministic time line. I don't see why things being what they are implies that there's no volition.

Nate T.

Post 13

Saturday, August 7, 2004 - 1:02am

How does this follow? As I've mentioned before, I'm not denying the existence of the consequences of a correct theory, just the existence of the analogies used to describe the theory.

It's not that the "space-time manifold" is the explanation. It's that "the data, when plugged into a mathematical scheme involving a manifold (which you could think of as space and time) results in consequences which correspond to reality." You shouldn't assume that the magnetic field or any such thing exists merely because invoking it is useful for describing reality-- that's reification.

Do you believe in Objective reality? Do you believe that reasoning by a sufficiently clever mind is *fully* capable of grasping *any* part of that reality? These are things I agree with Objectivists on. If you believe in Objectivist metaphysics you have to answer yes to both questions.

Given that you do agree with an Objectivist metaphysics, you then have to agree that there is in principle *no* unbridgeable gap between our *conception* of any part of reality and *reality itself* (If you think that there is an unbridgeable gap then you are a Kantian).

That's what Objectivist metaphysics means: (1) That there are *things* out there in reality which are *not* just constructs in human minds, and (2) Minds can fully describe any of these things. If you deny 1 you are mystic ()you would be saying that parts of reality exist only in your mind) and if you deny (2) you are a mystic also (you would be saying that reason cannot fully grasp reality)

So you must agree that *in principle* a sufficiently clever mind can form a *perfect* model of any part of reality. Of course in practice our models are often far from perfect, but if you believe in Objectivist metaphysics then you must agree that *in principle* they *could* be perfect.

And we mustn't forget that the picture is just that-- a picture.

A theory starts off as just a picture, but If that theory survives critisism, makes accurate predictions over and over again etc better than all other theories, the theory represents our best available *description* of what reality actually *is*. It's not just an analogy or picture any more, it becomes the best available model of reality. Go back to what I said above:

"That's what Objectivist metaphysics means: (1) That there are *things* out there in reality which are *not* just constructs in human minds, and (2) Minds can fully describe any of these things. If you deny 1 you are mystic ()you would be saying that parts of reality exist only in your mind) and if you deny (2) you are a mystic also (you would be saying that reason cannot fully grasp reality)"

If you claim that the best available theory is *just a construct* you are denying (1) or (2). A rational person *has* to accept the best available model of some aspect of reality has providing an actual model of what is really out there until proven otherwise. Repeating what I said above:

"So you must agree that *in principle* a sufficiently clever mind can form a *perfect* model of any part of reality. Of course in practice our models are often far from perfect, but if you believe in Objectivist metaphysics then you must agree that *in principle* they *could* be perfect."

I'm certainly not saying that we accept every crack-pot theory that comes along as describing reality. I agree that in the beginning a theory is just a device. BUT after a theory has survived repeated criticism and testing and shown itself to be the best available theory regarding some aspect of reality

THEN a rational person has to accept it as actually describing what is *out there* until proven otherwise. I hope you can see that claiming that the best avaliable theory is still *just a construct* is actually to deny rationality and/or Objective reality.

To sum up:

(1) Objective reality really exists (there are things actually out there not just constructs in your head).

(2) A sufficiently clever mind can in principle fully grasp (i.e in princple form a perfect model of) anything out there.

(3) A theory starts off as just a device, but after it has repeatedly survived criticism and made predictions better than all other rival theories, the theory becomes the best available theory

(4) Within the context of all the knowledge to hand , a rational person has to accept the best available theory as accurately describing things that are actually out there (i.e Objective reality) until proven otherwise, or else you are simply flatly denying Objectivist metaphysics. To say that that the best theory is 'just a device' is to say that according to everything you currently know, it's all just a construct in your head and/or your reasoning is all wrong.

Post 14

Saturday, August 7, 2004 - 8:47am

I am pointing to the observed fact that in the real world people are assigning probablities to events all the time using probability theory, and probability theory has proven to be very useful to people. This requires explanation. Then I point out we cannot make sense of these probabilities without Many Worlds. No alternative theory explains why these probabilities work. Therefore this is strong evidence that Many Worlds is correct.

Can you explain, then, why we cannot make the similar argument:

�I am pointing to the observed fact that in the real world people are forming concepts all the time, and a conceptual epistemology has proven to be very useful to people. This requires explanation. Then I point out that we cannot make sense of these concepts without the Universe of Forms. No alternative theory explains why these concepts work. Therefore this is strong evidence that the Universe of Forms is correct.�

The problem in both cases is the same. Both are an attempt to explain an epistemological fact with a metaphysical explanation. You appeal to the axiom �That there are *things* out there in reality which are *not* just constructs in human minds,� which is true. But the converse is not true�not every construct in human mind corresponds to a thing in actual reality. You will never find the concept of �spoon� in actual reality, outside of any consciousness. Neither will you find �a 55% probability� in actual reality�everything in reality either is, or is not. (What Objectivism denies is not that mental constructs exist, but that they can be formed arbitrarily without reference to reality. The concept �spoon� does not exist in reality, but it would still be wrong to try to categorize something orange, furry, and spherical within that concept.)

So yes, you are correct that probabilities require explanation, but a metaphysical explanation is inappropriate. They are explained by the fact that conceptual minds are able to categorize actual events into groups such as “races run by horse A” or “presidential elections with an incumbent candidate with an approval rating of X percent,” and observe the frequency of certain resultant events within those categories.

Post 15

Saturday, August 7, 2004 - 8:56am

Marc Geddes said:

Within the context of all the knowledge to hand , a rational person has to accept the best available theory as accurately describing things that are actually out there (i.e Objective reality) until proven otherwise, or else you are simply flatly denying Objectivist metaphysics. To say that that the best theory is 'just a device' is to say that according to everything you currently know, it's all just a construct in your head and/or your reasoning is all wrong.

I can invent the concept of kinetic energy, which is mathematically defined as on half the product of the mass of an object and the square of its speed. I can then invent the concept of potential energy in terms of the mathematical relation between a force and the distance moved.

Now, I can define the action of an object in terms of the kinetic and potential energies summed over time. It can be shown that the path that an object actually follows in the presence of this same force that was used to define the potential energy is that path which minimizes the action. And, this method exactly reproduces the results obtained by applying Newton's second law of motion.

So, what is the ontological status of kinetic energy, potential energy, and action? Are they "out there in reality"? Or are they mathematical concepts that make the solution of some classical mechanics problems easier? Or is there another choice?

Thanks,
Glenn

Post 16

Sunday, August 8, 2004 - 1:35pm

Marc, Nate,

So you must agree that *in principle* a sufficiently clever mind can form a *perfect* model of any part of reality.

A "model" is not required at all for the knowledge to be perfect. The model is always only a metaphor or way or "picturing" what abstract scientific principles say.

There is only one perceivable reality, the physical one we directly perceive. Everything else that is put into terms of the perceivable to represent the abstract is only a rhetorical device, from common expressions like, "thinking in circles," to picturing quantum phenomena as "wave/particle" dualities.

Reification is exactly the fallacy you, and almost all scientist commit when they forget their metaphors are only metaphors, as Nate said.

These are both mistaken:

(1) Objective reality really exists (there are things actually out there not just constructs in your head).

(2) A sufficiently clever mind can in principle fully grasp (i.e in principle form a perfect model of) anything out there.

Objective reality is the reality we directly perceive, everything else is an attempt to explain the nature of that directly perceived physical world. The pictures, models, and metaphors of science are only to help us "grasp" those aspects of the perceived physical world that are otherwise hard to "imagine." The objective reality is not "out there" it is "in there," that is, it is in the nature of the physical existents whose behavior the scientific theories and formulas explain.

There is no such thing as a, "perfect model," because they are all only models, and any model that will help us picture the math and behavior of physical existence is suitable.

This reification of the metaphors of science is a new kind of "supernaturalism." Scientist and students who swallow this view are the mystics of this age. It makes them believe in things like, "other worlds," and dimensions that have dimensions, like strings that have length.

It is the grossest of subjectivism, claiming the "real" world is the world as I picture it in my head, not the world we actually directly perceive. It is the denial of Objectivism.

Regi

Post 17

Tuesday, August 10, 2004 - 1:03am

Objective reality is the reality we directly perceive, everything else is an attempt to explain the nature of that directly perceived physical world. The pictures, models, and metaphors of science are only to help us "grasp" those aspects of the perceived physical world that are otherwise hard to "imagine."

Regi old fellow,

If all we ever ascribed reality to was what we could directly perceive, man would never have come out of the caves. All they would have ever believed in was what their senses immediately conveyed to them. The whole basis of science and philosophy is the idea that there is deeper reality behind the one we currently perceive, and we can use indirect observation and reasoning to determine what this reality is. The purpose of science and philosophy is to understand and explain *reality*, not restrict our conception of reality to things we can directly observe.

Here's a very simple example which conveys the point: Ask someone who has never been to Egypt what the Great Pyramids look like. Chances are they know. But how? After all, they have never directly perceived the pyramids with their senses. Instead they know through *pictures* they saw in books or on T.V. But should this disqualify their knowledge? Of course not. They are justified in believing that there is a *correspondence* between the pictures of pyramids and the pyramids themselves because of their rational *understanding* of where the pictures came from.

Similarly, scientists do not need to directly perceive something to ascribe reality to their conceptions. If they have indirect evidence combined with a causal rational understanding, they are entitled to believe that there is at least *some* degree of correspondence between their model of reality and reality itself.

Just because entities are not directly observable now, doesn't mean that science won't find a way to observe them directly at some future time. The famous example here is the atom. Philosophical arguments for these existed from the time of the Greeks, but logical positivists refused to believe in atoms because no one could directly observe them. They ridiculed scientists, saying that 'atoms' were 'just a device' and it was 'reification' to ascribe reality to these 'unobservables'. But lo and beyond, eventually someone invented a device (the Scanning Tunneling Microscope) which let scientists directly observe atoms. If scientists had believed the positivists, progress in chemistry would have ground to a stand-still far before this. Another example is the instance of viruses. No one could observe them at the time they were proposed either and the positivists said that they therefore didn't exist. If the positivists had had their way, no medicinal progress would ever have been made.

It is the grossest of subjectivism, claiming the "real" world is the world as I picture it in my head, not the world we actually directly perceive. It is the denial of Objectivism.

Regi

You've betrayed a total lack of understanding about the basic principles of rationality Regi. We sure as heck don't know what will turn out to be observable or not, so we shouldn't made advance judgements about what is and is not a part of concrete reality. the nature of reality is what we should be trying to find out, not limit in advance. It is the grossest of subjectivism to claim that "real" world is simply the world you can directly perceive with your senses at the moment.

Who is the most of a subjectivist: the 5 year old who thinks that the whole of reality is composed only of the things he can immediately see before him in his cot, or the 5 year old smart enough to use rudimentary reasoning to determine that there is a much wider reality beyond the one he can currently observe from his cot?

So, what is the ontological status of kinetic energy, potential energy, and action? Are they "out there in reality"? Or are they mathematical concepts that make the solution of some classical mechanics problems easier? Or is there another choice?

Thanks,
Glenn

The status of some scientific concepts is indeed unclear. I certainly don't say that all useful scientific concepts exist in concrete reality.

Can you explain, then, why we cannot make the similar argument:

�I am pointing to the observed fact that in the real world people are forming concepts all the time, and a conceptual epistemology has proven to be very useful to people. This requires explanation. Then I point out that we cannot make sense of these concepts without the Universe of Forms. No alternative theory explains why these concepts work. Therefore this is strong evidence that the Universe of Forms is correct.?

The difference between concepts and the probabilities is that you can compare a lot of different concrete things, and the concept from them, so you're not justified in postulating a world of Universal forms. For probabilities about unique events how-ever (such as the upcoming Presidential election in the U.S), the given context occurs once and only once so no sense can be made of the probability assignation without alternative universes.

The probability argument for Alternative Universes was not a good example anyway. Too much of an abstract and advanced argument. There are many other arguments for alternative universes. For instance how do you explain the classic quantum two-slit experiment in light of this latest reported version of it?

Very rough description recapping the famous experiment and this latest twist on it: light passes through a screen with two slits and hits the wall behind them. When only one slit is open, the light simply spreads out from that one slit and leaves a continuous bright patch on the wall. But with two slits open, you get an interference pattern on the wall - distinctive bands of light and dark - (the light from the second slit is spreading out and interfering with the light from the first slit).

You can cut down the intensity of the light so that only ONE SINGLE PARTICLE OF LIGHT (a photon) passes through the slits at a time. This latest experiment verifies which slit each individual particle travels through. With only one slit open, single particles pass through this one at a time and bang, bang, bang they each leave little dots on the wall as they hit it. Eventually when enough particles of light have been sent the dots on the wall add up to the continuous patch of light spreading out over the wall you'd see if you'd sent them all at once. No problem so far. But the mystery of course comes about when you open both slits and send particles of light through ONE AT A TIME (so that each time one particle moves through one of the two slits at random). The dots start building up as individual particles hit the wall but eventually THE PATTERN ON THE WALL IS THE INTERFERANCE PATTERN OF LIGHT AND DARK BANDS. Merely open the second slit mysteriously changes the behavior of particles traveling through the first slit. The particles are going through one at the time remember. Nothing in this universe can be passing through that second slit. YET IT IS AS IF A GHOSTLY PARTICLE OF LIGHT HAS PASSED THROUGH THAT SECOND SLIT AND INTERFERED WITH THE PARTICLE PASSING THROUGH THE FIRST SLIT. The only coherent realist interpretation is that particles of light from alternative universes are causing the interference. So because this latest reported experiment verifies that definitely only one particle is going through at a time and determines which slit each particle is going through, you seem to have both the wave and particle aspect co-existing. So I actually think it greatly strengthens the case for alternative universes.

Post 18

Tuesday, August 10, 2004 - 6:05am

YET IT IS AS IF A GHOSTLY PARTICLE OF LIGHT HAS PASSED THROUGH THAT SECOND SLIT AND INTERFERED WITH THE PARTICLE PASSING THROUGH THE FIRST SLIT. The only coherent realist interpretation is that particles of light from alternative universes are causing the interference.

Well, if you're right, then this does at least give us some way to prove through experimentation the reality of �alternate universes.� If the particle is being affected by a particle in another universe, then that suggests that there is some transmission of information (and force, even?) between universes. If this is the case, then there should be a way to construct an experiment which allows us to indirectly observe the path of the particle in the other universe.

Of course, usually people seem say that there is no way to observe or get information from the alternate universes, so this does sound kind of contradictory.... (I know, I can hear it now: �Check your premises.�)

I'm still going to say that it makes just as much sense to posit demons who lurk in all small narrow spaces and throw photons around in random directions to confuse people. ;-)

Post 19

Tuesday, August 10, 2004 - 10:27am