> Il 27 dicembre 2017 alle 23.24 Brent Meeker <[email protected]> ha scritto: > > So you think Bruno's theory fails because spacetime is discrete?
According to Deutsch "Every finitely realizable physical system can be perfectly simulated by a universal model computing machine operating by finite means." (It is the Church-Turing-Deutsch principle, I guess). Whether space-time is a finitely realizable physical system frankly I do not know. Feynman wrote "It always bothers me that according to the laws as we understand them today, it takes a computing machine an infinite number of logical operations to figure out what goes on in no matter how tiny a region of space, and no matter how tiny a region of time. How can all that be going on in that tiny space? Why should it take an infinite amount of logic to figure out what one tiny piece of space/time is going to do? So I have often made the hypothesis ultimately physics will not require a mathematical statement, that in the end the machinery will be revealed and the laws will turn out to be simple, like the chequer board with all its apparent complexities. But this is just speculation." (The Character of Physical Law - Ch. 2) > However, gamma ray propagation from distant supernova show no > dispersion, which implies that spacetime is smooth to severl orders of > magnitude below the Planck scale. > > But either way the physics a cannot be compared to Bruno's theory > because his theory makes not definite prediction even about the > existence of spacetime. > > Brent > > On 12/27/2017 1:22 PM, 'scerir' via Everything List wrote: > > > Brent wrote: > > > > A good idea, but I don't see that these "predictions" of computationalism > > have actually been derived. I think most of them are aspirational. For > > example, what is the proof that spacetime is continuous - in fact what is > > the proof there is such a thing as spacetime? > > > > -------- > > Actually Einstein wrote: "reality cannot at all be represented by a > > continuous field." (The Meaning of Relativity, Princeton Science Library, > > 1988, p. 160). In a letter to Hans Walter Dällenbach (1916) Einstein also > > wrote: “But you have correctly grasped the drawback that the continuum > > brings. If the molecular view of matter is the correct (appropriate) one, > > i.e., if a part of the universe is to be represented by a finite number of > > moving points, then the continuum of the present theory contains too great > > a manifold of possibilities. I also believe that this too great is > > responsible for the fact that our present means of description miscarry > > with the quantum theory. The problem seems to me how one can formulate > > statements about a discontinuum without calling upon a continuum > > (space-time) as an aid; the latter should be banned from the theory as a > > supplementary construction not justified by the essence of the problem, > > which corresponds to nothing “real”. But we still lack the mathematical > > structure unfortunately. How much have I already plagued myself in this > > way!”. > > > > See also http://holometer.fnal.gov/ > > -- > 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. -- 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.
