Re: Closer To Truth interview

On 24/05/2013, at 0:13, "hibbsa" <hibbsa-/[email protected]> wrote:

> 
> 
> --- In [email protected], David Deutsch <david.deutsch@...> wrote:
> >
> > On 17 May 2013, at 00:50, hibbsa <hibbsa@...> wrote:
> > 
> > > --- In [email protected], David Deutsch <david.deutsch@> wrote:
> > >> 
> > >> On 15 May 2013, at 20:49, hibbsa <hibbsa@> wrote:
> > >> 
> > >>> It seems to me you need conscious decisions for multiverse histories to see 
> > >> 
> > >> Does that mean "you need conscious decisions for multiverse histories to be conscious of..." 
> > >> 
> > >> If so, then yes: consciousness can't exist at all in the absence of consciousness.
> > >> 
> > >>> macroscopic divergence of a significant kind. 
> > >> 
> > >> 
> > >> What does 'seeing macroscopic divergence' mean? Presumably it doesn't mean 'being conscious of more than one universe'. Perhaps it means the existence of apparent randomness affecting macroscopic observables. But you don't need consciousness for that. All you need is amplification, which happens all the time and doesn't need any specially designed equipment.
> > >>> 
> > >>> Which sort of puts MWI in the dock for one of the problems it claims to solve: putting conscious observers at the heart of things.
> > >> 
> > >> It sort of puts MWI in the dock for *your* having put conscious observers at the heart of things, contrary to the predictions of quantum theory. Those are that multiple, approximately decoherent histories are a generic phenomenon in the multiverse.
> > >> 
> > >> -- David Deutsch
> > >> 
> > > 
> > > DD...I'm finding it hard to understand what you are saying in terms of what I am saying. 
> > > 
> > > I think it would help (me) if you answered my first question. Which I'll restate here, a bit clearer hopefully. 
> > > 
> > > Let's say 10^23 instances of approximately the same mole existed in this universe.
> > 
> > That sentence means that we are to consider 10^23 instances of a sample of, say, a gas, each of which would occupy 22.4 litres at standard temperature and pressure. You're right that I didn't realise that that is what you were referring to before.
> > 
> > > I know you'd need more,
> > 
> > I don't understand the thought-experiment you're envisaging, so I don't know what you'd need more of them for. 
> > 
> > > but let's say each of the 10^23 multiverse histories
> > 
> > I can't tell whether it's a coincidence that you're now envisaging the same number of multiverse histories as the number of separate instances in one universe that that you have just envisaged above, or whether this indicates that I have some misconception about what thought experiment you have in mind. But I assume from the following clause that you do mean both numbers:
> > 
> > > was represented by each of those moles in this universe. 
> > > 
> > OK, we have 10^23 multiverse histories of 10^23 samples, so we are considering 10^46 instances altogether.
> > 
> > > What extent would all 10^23 (or however many) moles react to exhibit the same emergent properties? 
> > 
> > Unfortunately I can't parse that sentence. But, first of all, all 10^23 instances in the same universe have *different* emergent properties, such as centre-of-mass position. Also, as I understand the thought-experiment you have set up, none of the 10^46 instances are interacting with each other. So none of them "react to exhibit" anything.
> > > 
> > > Or said differently, however many instances necessary to represent every multiverse history, of a litre H20 would boil at the same temperature? 
> > 
> > Unfortunately I can't parse that sentence either. But if you're asking: what proportion of the multiversal instances of a litre of water boil at the same temperature -- well, that question mixes two levels of explanation. The literal answer is zero: whatever exact microscopic meaning we might artificially attach to the approximate, emergent concepts 'boil' and 'temperature', the probability of a litre of water 'boiling' at exactly that 'temperature' is zero. 
> > 
> > -- David Deutsch
> >
> 
> DD - I'm still thinking about your reply here. 
> 
> There's a communication issue...we aren't talking about the same thing. 
> 
Hi Hibbsa,

I think I have an idea what you might be getting at - and I think I even understand your interest in this now. But a couple of questions arising first...

> 
> I think I'm talking about the reality of abstractions as you describe them in BoI. 
> 
Really? You might have to clarify the connection between *that* and this stuff about moles and cans of water.
> 
> It could be you are thinking in terms of there having to be fine tuning for these abstractions to emerge similarly across different multiverse histories of the same object. 
> 
Do you mean an abstraction like "the mole" or a "can of water" or...?
> 
> I don't understand why this is. Does water boil with similar characteristics in all multiverse histories of the same can of water heated to boiling, with the same sort of diversity of outcome as 10^30 or whatever cans of boiling water in this universe? 
> 
I think the answer is yes.

I understand your question can be put like this, and correct me if I am wrong:

If you could have 10^30 cans of water in this universe and boiled them all and then compared the results to boiling 10^30 cans of water each in a different universe, would the results be the same?

My guess is: yes, very similar indeed. The same laws of physics apply. We should expect some small number in *this* universe to boil almost instantly or not at all. Similarly when boiling one can of water in this universe, some very small number of counterparts in others boil almost instantly or not at all.

But now note this: the experiment is ruled out by what we know about this universe. Namely, there simply is not enough water to do that experiment (the universe is more massive and with fusion, we might be able to get there...) But even if there were sufficient water we could never (a) calculate the results or (b) process the results 
The reason for (a) and (b) is that the universe is accelerating and unless something new is discovered, we will run out of time to do the processing before dark energy pushes everything too far away (like the relevant observations you need to make for this experiment). 10^30 cans of water is just too much and would be spread too far and wide for us to ever check. But we don't need to if we just take what the laws of physics say seriously. And I think that is just a "yes" in answer to your question.
> 
> I'm sure I'm confused about something here...I just want you to be able to see what I'm confused about, if that's the way things are. 
> 
I hope my re-statement of your thought experiment helps.

Brett.

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