On Wed, Feb 19, 2014 at 12:39:59AM +0000, David Nyman wrote: > On 19 February 2014 00:15, Russell Standish <[email protected]> wrote: > > > On Tue, Feb 18, 2014 at 11:22:55PM +0000, David Nyman wrote: > > > On 18 February 2014 22:34, Russell Standish <[email protected]> > > wrote: > > > > > > On Tue, Feb 18, 2014 at 02:06:37PM +0000, David Nyman wrote: > > > > > > > > > > I must admit it hasn't been entirely clear to me why you decided > > that the > > > > > MGA can go through without addressing the counterfactuals, especially > > > > since > > > > > Maudlin felt he had to address them in his alternative formulation. I > > > > > appreciate that Maudlin proceeds by trivialising the amount of > > activity > > > > > involved in the computation whereas MGA relies on evacuating the > > notion > > > > of > > > > > physical computation itself, but does the latter approach obviate the > > > > need > > > > > to account for any possible counterfactual activity? > > > > > > > > > > > > > If the counterfactuals are physical (Multiverse situation), then we > > > > are automatically in a robust universe (for which the reversal is > > > > already addressed by step 7). > > > > > > > > > Right. Sorry if I'm being a bit slow. I can see that if there is a > > > Multiverse then we automatically get the physical counterfactuals in any > > > given situation. But I'm not sure that I get the point that a physical > > > Multiverse guarantees the actual physical computation of the UD (or > > rather > > > its completed trace), which I assume is necessary to the reversal (in the > > > sense that the infinity of computation intrinsic to the UD* is assumed to > > > swamp every competing measure). I guess that means that I haven't > > > understood quite what is meant by robust here. Can you help with what I'm > > > missing? > > > > Fair enough - it's a bit subtle. A quantum computation running in a > > Multiverse has all possible states of its input bits executed > > simulatenously. That is the meaning of a qubit. I can run a variant of > > the dovetailer algorithm that actually executes its program in > > parallel, exponentially speeding up the process. Our observed universe > > has sufficient quantum computing resources to be able to run enough of > > the UD to end up emulating conscious observers. > > > > It seems clear to me that the physical processes we see > > instantiating consciousness are quantum in nature, spread out over the > > Multiverse, executing a collection of programs like a dovetailer, > > including conscious ones. > > > > So whilst the Multiverse may not be strictly speaking robust in the sense > > of having infinite computational resources, it does have sufficient > > resources to emulate enough of the dovetailer to include consious > > programs, and in fact is doing so, by virtue of the fact we observe > > consioud processes. This is enough for the distinction beween step 7 > > and step 8. > > > > Ah, right. So one has to keep in mind that it takes the running of the UD > (or at least enough of it) to support a coherent formulation of CTM in the > first place (essentially because once one assumes that consciousness > supervenes on computation it becomes illegitimate to place arbitrary > restrictions on what computations are deemed to exist). If so, assuming > CTM, one can then use the a posteriori fact of conscious observation to > justify the claim that the Multiverse must be robust enough (in that sense) > to support the UD, especially given the independent plausibility of this > assumption. Is that it, more or less? > > You're right that it's subtle. It's easy to miss (Edgar for one seems to > miss it completely). It seems to require a conceptual leap to the necessity > of a computational infinity with observer selection as the arbitrator of > the stability of physical appearance (the Programmatic Library of Babel). > Perhaps the UDA could spell this out more explicitly in step 7 (I can't > bring to mind what it actually says at that point)? >
I have promised (to myself) to write a paper discussing these issues (something along the lines of "MGA revisted"), because I don't think the current literature adequately addresses this. But I have so many projects! Whilst I don't think the Multiverse necessarily entails the leap to computational infinity, I think it must have sufficient computational power to entail the independence of physics from ontology (of the concrete quantum universe). Anyway, hopefully I can get to that paper so that we can discuss this more. -- ---------------------------------------------------------------------------- Prof Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Professor of Mathematics [email protected] University of New South Wales http://www.hpcoders.com.au ---------------------------------------------------------------------------- -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
