How does it know to do that? — fishfry

Your attributing an agency here, an ‘it’ that ‘does’ something. But the same ‘it’ is what you’re trying to explain, so there’s an issue of recursion involved.

Your attributing an agency here, an ‘it’ that ‘does’ something. But the same ‘it’ is what you’re trying to explain, so there’s an issue of recursion involved. — Wayfarer

Only speaking loosely. Ignorant of the physics. Asking if there's an explanation of why all states must occur. Is this all as in all? Or all as in statistically all, but possibly missing one or two with no harm done to the universe?

I don't understand why you think I'm trying to explain anything. Tom said that during inflation all states are created. I'm asking questions about that.

You know, "How does it know how to do that?" seems pretty clear to me. If I said, "How does a bowling ball know how to fall to the earth?" you wouldn't think I am talking about agency, but rather asking how gravity works. So how does the universe know how to generate all the states? That's a pretty common figure of speech I think.

That's very interesting. How does it know to do that? In the early moments of the universe it's cranking out all these possible configurations, and it's only got one more left. How does it know that? What if it forgets to do one particular configuration? Can it go back and do it later? Can the universe continue to exist or does this one single imbalance make the universe unstable in some way? — fishfry

Much of the attraction of the Multiverse is that it removes the requirement to explain particular initial conditions and physical constants because all are realised somewhere. If you wish to single out a single set of initial conditions for being forgotten or of being uniquely instantiated, then you are going to need a different physical theory than we already have. As I have mentioned a few times, it is a prediction of Inflation that all initial conditions are realised, and that their statistical distribution is ergodic.

Tegmark's view on how these initial conditions obtain is that the early universe, during Inflation (i.e. the inflaton field), is in a superposition of all its possible states. If this is the case (which it must be if physics is unitary) then the same fundamental physical process gives rise to the type 1 and 2 multiverses as type 3. This physical process is decoherence.

You know I just don't believe this duplicate earth story. Say there's a universe or a multiverse and it's got every possible state represented infinitely many times ... except there is one state that just happens to only occur once, by incredible amazing luck ... one little blue watery planet with bad politics, third from the sun ... and it's the only one like it in the entire multiverse. — fishfry

So, you prefer "incredible amazing luck" theory to our best theory of the universe? Do you even aspire to rationality?

But we're making progress if you agree that ergodicity by itself is not sufficient. — fishfry

Now you are straw-manning.

Only speaking loosely. Ignorant of the physics. Asking if there's an explanation of why all states must occur. Is this all as in all? Or all as in statistically all, but possibly missing one or two with no harm done to the universe? — fishfry

All possible states must occur because of:

1. Infinity, which I have mentioned several times previously. Space must be infinite.

2. Mass fluctuations approach zero on large scales.

3. The mass densities at any set of points has a multivatiate Gaussian probability distribution.

Conditions 2 and 3 may be combined into the weaker condition that the correlation functions of all orders vanish in the limit of infinite spatial separation.

Together the above conditions are called ERGODICITY

The above prediction of Inflation can be traced back to the state of the conjectured scalar field, called the Inflaton, that permeates all of the infinite master space-time that our, and all the other universes and multiverses inflate from. The harmonic oscillator equations that determine the ground state of the Inflaton give a Gaussian wave function.

4. Infinity. But I've already mentioned that.

5. The Bekenstein Bound - the number of possible states scales with surface area, not volume.

All possible states must occur because of:

1. Infinity, which I have mentioned several times previously. Space must be infinite.

2. Mass fluctuations approach zero on large scales.

3. The mass densities at any set of points has a multivatiate Gaussian probability distribution.

Conditions 2 and 3 may be combined into the weaker condition that the correlation functions of all orders vanish in the limit of infinite spatial separation.

Together the above conditions are called ERGODICITY — tom

Thank you for clarifying. I don't feel that you're engaging with my point.

Your bullet items are probabilistic. And you are applying probability theory to an infinite event space.

It is a fact that when you extend finite probability theory to infinitary realms, you lose certainty. Your event space could be extremely well-behaved statistically, and still allow for many anomolies and exceptions. This is the difference between the phrases "surely" and "almost surely." These are technical terms in probability theory. Almost surely means that something happens everywhere except on a set of measure zero. That means that there can be many individual exceptions to the global statistical properties of the event space. And measure zero sets can be quite large and complicated.

I would certainly agree with the statement that given the premises of the discussion, there is almost surely a duplicate earth.

But that does not mean that it must necessarily happen. And this is the point you're not engaging with. The very infinitary probability theory that you're invoking allows for exceptional sets of measure zero.

You are applying without justification your intuitions and beliefs about finite probabilities to infinite ones. You are not giving sufficient consideration to measure zero sets and the loss of absolute certainty when we pass from finite to infinite probability theory.

This being a philosophy forum, it's worth noting that this is a point of epistemology. When you extend finite probability theory to infinite event spaces, you lose certainty. The theory requires the existence of measure zero sets; and sets of measure zero don't have any effect on the limiting behavior of the probability distributions. You have to take this into account when making metaphysical claims based on probabilistic arguments,

fishfry is correct

Your bullet items are probabilistic. And you are applying probability theory to an infinite event space. — fishfry

Are they probabilistic? Perhaps you could show what you mean by that, and which points comply with your meaning?

It is a fact that when you extend finite probability theory to infinitary realms, you lose certainty. — fishfry

Infinite realms? Loss of certainty?

You are applying without justification your intuitions and beliefs about finite probabilities to infinite ones. — fishfry

Intuitions, infinite probabilities?

You have to take this into account when making metaphysical claims based on probabilistic arguments, — fishfry

Metaphysical claims?

fishfry is correct — andrewk

Will you inform the Nobel Prize Committee?

Much of the attraction of the Multiverse is that it removes the requirement to explain particular initial conditions and physical constants because all are realised somewhere. — tom

Is that related to this point?

Fundamental constants are finely tuned for life. A remarkable fact about our universe is that physical constants have just the right values needed to allow for complex structures, including living things. Steven Weinberg, Martin Rees, Leonard Susskind and others contend that an exotic multiverse provides a tidy explanation for this apparent coincidence: if all possible values occur in a large enough collection of universes, then viable ones for life will surely be found somewhere. This reasoning has been applied, in particular, to explaining the density of the dark energy that is speeding up the expansion of the universe today.

DOES THE MULTIVERSE REALLY EXIST? (cover story). By: Ellis, George F. R. Scientific American. Aug2011, Vol. 305 Issue 2, p38-4.

Because, if that is the motivation, then what is behind it? That the suggestion of a 'fine-tuned Universe' is one which most scientists would rather avoid?

Because, if that is the motivation, then what is behind it? Is the suggestion of a 'fine-tuned Universe' one which most scientists would rather avoid? — Wayfarer

The Level 2 Multiverse solves the Fine-Tuning Problem.

Will you inform the Nobel Prize Committee? — tom

Your mistake is in mathematics, not in physics, so if you want to invoke a committee, it would be for something like the Fields medal, not the Nobel prize.

The Level 2 Multiverse solves the Fine-Tuning Problem. — tom

Ask yourself why it’s a problem that needs solving.

Ask yourself why it’s a problem that needs solving. — Wayfarer

Science is about formulating problems and seeking solutions for them in terms of explanations, i.e. accounts of what exists in reality, how it behaves, and why.

So sure, if I look at the constants of nature, a perfectly natural question arises as to why they take particular values. Wouldn't it be nice to find a theory that predicts them? And if I look a little deeper and discover the sensitivity of Reality to slight changes in some of them, the slightly deeper question arises about why the had to take these values for there to be anyone to be questioning them.

In the face of Fine-Tuning it is impossible to maintain the Principle of Mediocrity without the Multiverse.

Your mistake is in mathematics, not in physics, so if you want to invoke a committee, it would be for something like the Fields medal, not the Nobel prize. — andrewk

Perhaps you would like to get in touch with Max Tegmark and give him the bad news?

Perhaps you would like to get in touch with Max Tegmark and give him the bad news? — tom

I am not aware that Tegmark made the mistake of aggressively claiming that probability one means 'certain' in an infinite sample space, as you did.

I suggest you read up on the precise, important mathematical notion of 'almost surely' (also rendered from time to time as 'a.s', 'almost certain' or 'a.c')

I am not aware that Tegmark made the mistake of aggressively claiming that probability one means 'certain' in an infinite sample space, as you did. — andrewk

Being unaware is not an argument.

OK then, my answer is simply "No, I do not intend to contact Mr Tegmark, as I have no reason to believe he needs correcting".

I see your suggestion about contacting him as irrelevant, as was the reference to the Nobel committee.

OK then, my answer is simply "No, I do not intend to contact Mr Tegmark, as I have no reason to believe he needs correcting".

I see your suggestion about contacting him as irrelevant, as was the reference to the Nobel committee. — andrewk

When you have calmed down from your hissy fit, consider this:

An ergodic random field whose harmonic oscillator coefficients span {1,2,3,4,5,6} with a Gaussian distribution centred on 3.5. The field is in a state of superposition and decoheres for infinite time. What is the probability that the decoherence branch with initial condition "4" will be encountered in the multiverse?

Are you of the opinion that the answer is 1? If I agree to that opinion for the sake of furthering the discussion, how do you think that helps your argument?

So sure, if I look at the constants of nature, a perfectly natural question arises as to why they take particular values. Wouldn't it be nice to find a theory that predicts them? — tom

Maybe not. Maybe science will never explain the various constants, the 'six numbers' that purportedly underlie everything. Maybe the attempt to explain at that level is forever beyond science, and produces only pseudo-science, 'multiverses' being an example.

Are they probabilistic? Perhaps you could show what you mean by that, and which points comply with your meaning?

Infinite realms? Loss of certainty?

Intuitions, infinite probabilities?

Metaphysical claims? — tom

Before I compose a detailed reply to each of the points you raised; can you please tell me which part of my post is giving you trouble? Do you not understand the distinction between almost surely and surely? Or do you understand it but think it doesn't apply in the present discussion? Or think that Tegmark doesn't think it applies? I just want to figure out what level of misunderstanding we're having on this point. There's no question that I'm accurately relaying the math of infinitary probabllity theory. So there must be some disconnect between that and the physics.

Maybe not. Maybe science will never explain the various constants, the 'six numbers' that purportedly underlie everything. Maybe the attempt to explain at that level is forever beyond science, and produces only pseudo-science, 'multiverses' being an example. — Wayfarer

You mean maybe the six numbers are magical? And of course the usual slur. How predictable!

Before I compose a detailed reply to each of the points you raised; can you please tell me which part of my post is giving you trouble? Do you not understand the distinction between almost surely and surely? Or do you understand it but think it doesn't apply in the present discussion? Or think that Tegmark doesn't think it applies? I just want to figure out what level of misunderstanding we're having on this point. There's no question that I'm accurately relaying the math of infinitary probabllity theory. So there must be some disconnect between that and the physics. — fishfry

I look forward to your refutation of our best Cosological theory, right here, on this forum, by a true expert.

You mean maybe the six numbers are magical? — tom

Not magical - simply the terminus of explanation.

The short version: the ‘many worlds theory’ is based on avoiding the philosophically unsavoury implications of the observer problem.

The multiverse - ditto for the unsavoury implications of the fine-tuning problem.

They’re both metaphysical issues which physicalists are trying to solve by infinite ad hoc additions to physical theory.

Of course I could never substantiate such an argument, so I won’t pursue it. Consider it a footnote.

They’re both metaphysical issues which physicalists are trying to solve by infinite ad hoc additions to physical theory. — Wayfarer

Funny, I see them as subtractions.

The short version: the ‘many worlds theory’ is based on avoiding the philosophically unsavoury implications of the observer problem.

The multiverse - ditto for the unsavoury implications of the fine-tuning problem.

I find them elegant solutions. The unsavory feeling you get seems to be a challenge to a religious view of what you are. Yes, I would find that unsavory, and cause for further investigation, not a terminus because it threatens my biases.

I look forward to your refutation of our best Cosological theory, right here, on this forum, by a true expert. — tom

That's a pathetic response.

A non-pathetic response to the question I asked you would be one of the following:

* "I don't quite get this measure zero business, can you explain?" or

* I get measure zero ,but it doesn't apply in this case because _______"; or

* I get measure zero and Tegmark gets measure zero but Tegmark says it doesn't apply in this case because _____."

If you make a statistical argument on an infinite probability space and you don't take measure zero events into account, you have to say why they're not relevant in the particular case under discussion. If you can't formulate a coherent reply, you don't understand the ideas you're promoting.

The unsavory feeling you get seems to be a challenge to a religious view of what you are. — noAxioms

On the contrary - the philosophical problem posed by the ‘observer problem’ and by the ‘fine-tuned Universe’ argument, is in part the motivation for the MWI and multiverse theories (see this quote). You see the same motivation again in respect of whether the Universe can be said to have a beginning: 'While many of us may be OK with the idea of the big bang simply starting everything, physicists, including Hawking, tend to shy away from cosmic genesis. “A point of creation would be a place where science broke down"(seeWhy Physicists Can't Avoid a Creation Event).

My view is 'religious' mainly because it questions materialism - not because I am in the business of defending creation myths. But in today's world, to doubt the dominant narrative is to be regarded as 'religious' - because the dominant narrative now functions as a religion, in the sense of being normative for how educated people are supposed to think.

I understand perfectly that religious creation myths are indeed myths. Whatever is empirically demonstrated by science is an indisputable fact; and I will never dispute the facts. I'm questioning conjecture which I claim is at least partially motivated by philosophical or metaphysical considerations. They influence what kinds of ideas will be considered, and what avoided, on the basis of pre-existing commitment - otherwise known as a bias.

If you make a statistical argument on an infinite probability space and you don't take measure zero events into account, you have to say why they're not relevant in the particular case under discussion. If you can't formulate a coherent reply, you don't understand the ideas you're promoting. — fishfry

This is really depressing. There are no measure zero events, as explained multiple times in this thread.

Still waiting for your demolition of Cosmic Inflation, you are the self proclaimed expert.

There are no measure zero events, as explained multiple times in this thread. — tom

Please explain it to me. If there are no measure zero events, then NO distribution of states to universes is possible. Just like if you flip infinitely many coins. Whatever result comes up, that was a measure zero event.

It's only when you aggregate all the possible results as either "Some state only happens once" versus "All states happen infinitely many times," that the latter has probability 1. That's because you're aggregating uncountably many measure zero events, and comparing that to an aggregate of countably many measure zero events.

If you randomly assign one of finitely many possible events to each of infinitely many universes or regions of an infinite universe, the probability of ANY PARTICULAR result is zero. You can just multiply out the probabilities to see that.

There are no measure zero events, as explained multiple times in this thread. — tom

I have not noticed such an explanation. But it's a long thread and I haven't read it all. Can you please point to one such explanation?