On Sat, Dec 7, 2019 at 7:50 PM Philip Thrift <[email protected]> wrote:
> On Saturday, December 7, 2019 at 12:22:01 AM UTC-6, Bruce wrote: >> >> On Wed, Nov 27, 2019 at 8:55 AM Bruce Kellett <[email protected]> wrote: >> >>> >>> Quantum mechanics itself is not counterfactually definite. Einstein was >>> wrong about this. A free electron is described by a wave packet which is a >>> superposition of states of definite momentum and position. There is no >>> actual "position" for the electron until it interacts with a screen or some >>> similar device. This is demonstrated by simple two-slit interference. There >>> is no pre-existing position, unless you want to embrace Bohm's pilot wave >>> theory, in which the electron does have a definite, though unknown, >>> position at all times. >>> >> >> I have come across an interesting video >> >> https://www.youtube.com/watch?v=5D9HkoHScdY >> >> in which Gerard 't Hooft, Roger Penrose, Tim Maudlin and a couple of >> others talk about interpretations of quantum mechanics from their different >> perspective. I found the segment by Tim Maudlin particularly interesting, >> given his new book on the philosophy of quantum mechanics. His segment >> starts at about the 10 minute mark. But the other contributions also have >> some interest -- particularly Philip Ball towards the end (about the 20 >> minute mark). >> >> No definite conclusions are advocated, but it is interesting to hear the >> different perspectives. >> >> Bruce >> > > > > > Not sure what this is. > So why did you raise it? You have a habit of throwing irrelevancies around, Phil. It is not an endearing trait. Bruce > > *Tim Maudlin - Linear Structures* > > https://academic.oup.com/aristoteliansupp/article-abstract/84/1/63/1780015 > > The standard mathematical account of the sub-metrical geometry of a space > employs topology, whose foundational concept is the open set. This proves > to be an unhappy choice for discrete spaces, and offers no insight into the > physical origin of geometrical structure. I outline an alternative, the > Theory of Linear Structures, whose foundational concept is the line. > Application to Relativistic space-time reveals that the whole geometry of > space-time derives from temporal structure. In this sense, instead of > spatializing time, Relativity temporalizes space. > > https://www.sciencedirect.com/science/article/pii/S1355219815000842 : > > Causal set theory and the theory of linear structures (which has recently > been developed by Tim Maudlin as an alternative to standard topology) share > some of their main motivations. In view of that, I raise and answer the > question how these two theories are related to each other and to standard > topology. I show that causal set theory can be embedded into Maudlin׳s more > general framework and I characterise what Maudlin׳s topological concepts > boil down to when applied to discrete linear structures that correspond to > causal sets. Moreover, I show that all topological aspects of causal sets > that can be described in Maudlin׳s theory can also be described in the > framework of standard topology. Finally, I discuss why these results are > relevant for evaluating Maudlin׳s theory. The value of this theory depends > crucially on whether it is true that (a) its conceptual framework is as > expressive as that of standard topology when it comes to describing > well-known continuous as well as discrete models of spacetime and (b) it is > even more expressive or fruitful when it comes to analysing topological > aspects of discrete structures that are intended as models of spacetime. On > one hand, my theorems support (a). The theory is rich enough to incorporate > causal set theory and its definitions of topological notions yield a > plausible outcome in the case of causal sets. On the other hand, the > results undermine (b). Standard topology, too, has the conceptual resources > to capture those topological aspects of causal sets that are analysable > within Maudlin׳s framework. This fact poses a challenge for the proponents > of Maudlin׳s theory to prove it fruitful. > > > > https://pdfs.semanticscholar.org/1db1/0fc014a2182a572ad11f4253df26e6c54f0f.pdf > > @philipthrift > -- 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/CAFxXSLRB5%2Bg7e-MOG1Oq9VNhWrt%2BSMFkVJPxZaz72DThBQre-w%40mail.gmail.com.
