> On 14 Sep 2019, at 05:22, Alan Grayson <[email protected]> wrote: > > > > On Friday, September 13, 2019 at 4:08:23 PM UTC-6, John Clark wrote: > On Thu, Sep 12, 2019 at 10:26 PM Alan Grayson <[email protected] > <javascript:>> wrote: > > > Carroll also believes that IF the universe is infinite, then there must > > exist exact copies of universes and ourselves. This is frequently claimed > > by the MWI true believers, but never, AFAICT, proven, or even plausibly > > argued. What's the argument for such a claim? > > Of course it's been proven! It's simple math, there are only a finite number > of ways the atoms in your body, or even the entire OBSERVABLE universe, can > be arranged so obviously if the entire universe is infinite then there is > going to have to be copies, an infinite number of them in fact. Max Tegmark > has even calculated how far you'd have to go to see such a thing. > > What I think you're missing (and Tegmark) is the possibility of UNcountable > universes. In such case, one could imagine new universes coming into > existence forever and ever, without any repeats. Think of the number of > points between 0 and 1 on the real line, each point associated with a > different universe. AG
Tegmark missed this? Deutsch did not, and in his book “fabric of reality”, he gave rather good argument in favour of Everett-type of multiverse having non countable universe. That makes sense with mechanism which give raise to a continuum (2^aleph_0) of histories, but the “equivalence class” brought by the measure can have lower cardinality, or bigger. Open problem, to say the least. > > Your closest identical copy is 10^12 light years away. About 10^76 light > years away there is a sphere of radius 100 light-years identical to the one > centered here, so everything we see here during the next century will be > identical to those of our counterparts over there. And 10^102 light years > away the is a exact copy of our entire observable universe. And all this is > true regardless of if the Many Worlds Interpretation of Quantum Mechanics is > correct or not, it only depends on the universe being spatially infinite. > > But our universe is NOT spatially infinite if its been expanding for finite > time, starting very small, as can be inferred from the temperature of the > CMBR. AG > > > Is there a copy of you > <https://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf> > > > Morevover, I don't believe a universe of finite age, such as ours which > > everyone more or less agrees began some 13.8 BYA, can be spatially infinite. > > I see no reason in principle why something can't be finite along one > dimension and infinite along another dimension. > > In general, one can of course have some dimensions finite and others > infinite. But if our universe is finite in time since the BB, 13.8 BY, its > spatial extent must be finite, since that's how long its been expanding. AG I agree with Grayson here. (Accepting a lot of premises, like the BB is the beginning of the physical reality, which I doubt). Bruno > > John K Clark > > > -- > 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] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/5a270b8e-3bf2-4d34-b0e7-4e0daa3cebce%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/5a270b8e-3bf2-4d34-b0e7-4e0daa3cebce%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/36A320C7-5089-4770-8203-4CB13FCF54FE%40ulb.ac.be.
