On 31 July 2014 19:17, meekerdb <[email protected]> wrote: > On 7/30/2014 4:57 PM, LizR wrote: > > On 31 July 2014 10:26, Russell Standish <[email protected]> wrote: > >> On Thu, Jul 31, 2014 at 10:08:52AM +1200, LizR wrote: >> > >> > PS One problem I have with uncountable infinity not being a feature of >> the >> > world is that it appears to scupper eternal inflation, and even >> universes >> > expanding exponentially. Does anyone have any comments on that? >> > >> >> Why? >> > > Because if space-time isn't an infinitely divisible continuum, it > presumably has some sort of granularity, and if it's blown up in size (or > squashed down) the grain size may become relevant. It's one of the "end of > the universe scenarios" mentioned by Max Tegmark in his recent book, that > the expansion of the universe makes the quantum granularity too large for > matter to continue to exist (in some way). > > > The evidence however is against spacetime granularity: > > Yes, also granularity is fundamentally at odds with Lorentz invariance (amongst other things). But something has to give in merging GR and QM and the nature of space-time is a possibility, as various attempted TOEs have assumed (string, LQG, CDT etc).
> I suppose that if you blow up space-time exponentially, you will rapidly > reach any existing grain size. If inflation would have blown up Planck-cell > sized chunks to anything vaguely macroscopic, for example, we wouldn't > expect any detail to exist below the expanded size. > > Macroscopic, in the sense of "classical acting, not quantum", is a matter > of degrees of freedom. So I think it would depend on how things were > "blown up". Just changing the Planck length would be simple rescaling and > nothing observable would change. So space quanta would have to get bigger > compared to something else fundamental. > Obviously Max isn't just assuming a scale change. -- 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/d/optout.
