On Wednesday, November 29, 2017 at 3:24:38 PM UTC, Bruno Marchal wrote: > > > On 29 Nov 2017, at 04:59, Bruce Kellett wrote: > > On 29/11/2017 2:29 pm, John Clark wrote: > > On Tue, Nov 28, 2017 at 9:05 PM, Brent Meeker < <javascript:> > [email protected] <javascript:>> wrote: > > >> > And how is the Eternal Inflation Multiverse fundamentally different from > the String Theory Multiverse? > > > > > > I didn't say they were different from each other; I said they were > different from the mulitple worlds of Everett which all share the same > physics with the same physical constant values. > > > I see no reason all the Everett worlds have the same physics, > > > Everettian worlds follow from assuming that the Schrödinger equation > applies everywhere without exception, so that all physical evolution is > unitary. A change in the underlying physics -- such as a change in the > value of fundamental constants, Planck's constant or Newton's constant for > example -- would not be unitary, so cannot occur in MWI. > > The same reasoning applies to the Level I multiverse from eternal > inflation -- same physics everywhere. However, the level ii multiverse from > the string theory landscape has physical constants and the number of > space-time dimensions varying from world to world. > > > Yes. The Everettian view of string theory leads to a multi-multiverse. > Perhaps 10^500 multiverses ... >
*Wow! What a coincidence! Same estimate as the landscape in string theory. Is this before or after Joe the Plumber did his experiments which adds universes according to the MWI? AG * > > > > > unless it turns out that only one sort of physics can happen. But lets > assume you're right, then the string theory multiverse must be larger than > the many worlds multiverse incorporating everything in Everett's version > and MORE; after all if it contains universes with radically different laws > of physics it must also contain more modest things like a world where my > coin came up heads instead of tails. > > > I would suggest that there is no such world. Whether a coin comes up head > or tails on a simple toss is not a quantum event; it is determined by quite > classical laws of physics governing initial conditions, air currents and > the like. > > > It depends. If you shake the coin long enough, the quantum uncertainties > can add up to the point that the toss is a quantum event. With some student > we have evaluate this quantitavely (a long time ago) and get that if was > enough to shake the coin less than a minute, but more than few seconds ... > (Nothing rigorous). > > > > > > > Also, in the Level I multiverse it is quite unlikely that the initial > conditions could differ to an extent such that everything was identical in > the two worlds up to your coin toss. I think Tegmark is wrong about this. > His argument (as outlined in his book) assumes that worlds are made up at > random out of the available constituents, so every way of filling > space-time units is realized somewhere. But this is wrong. Worlds are not > random objects, they follow the laws of physics, so given some initial > conditions, the future is determined in a deterministic Everettian MW > scenario. It is not the case that everything logically possible happens -- > only those things that follow from the initial conditions by deterministic > evolution happen. So although all possible initial conditions may be > realized somewhere, not everything can follow deterministically -- the laws > of physics cannot be broken. > > > OK. We agree on this. > > Bruno > > > > > Bruce > > -- > 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 > > ... -- 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 https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
