On Tue, Jun 29, 2021 at 1:13 AM Jason Resch <[email protected]> wrote:
> On Mon, Jun 28, 2021, 7:24 AM Bruce Kellett <[email protected]> wrote: > >> >> There is no well-defined theory of eternal inflation, so other worlds >> from this source are purely speculative. >> > > Inflation, in its simplest and most general forms is eternal. You need to > work to make a version that's not eternal. Eternal inflation is preferable > under Occam's razor. > You obviously know very little about inflation theory. If you take a simple inflaton potential, such as phi^2, then the inflation is eternal. But that simple potential does not fit the cosmological data. The best fits to the data require a single slow-roll potential with sensitively adjusted parameters. Such a potential does not give eternal inflation. String theory and its "landscape" is a failed attempt at a physical theory, >> and no credence can be placed in any supposed prediction of that theory. >> > > What's your opinion of the fine tuning coincidences? Do you think it is a > genuine mystery that calls for an explanation? > No. The quantum mechanical multiverse, arisong in the multi-worlds >> interpretation, must necessarily involve the same physics as we observe. >> > > Not necessarily. There are recent speculations that the laws of physics > themselves are determined by a quantum process: > > "Cosmic bio-friendliness is therefore the result of a sort of quantum > post-selection effect extended to the very laws of physics themselves." > -- Paul Davies in “The flexi-laws of physics” (2007) > Recent speculations are not established scientific facts. Besides, even if Davies is right, that does not show that the other worlds of MWI involve different physics. Application of the Schrodinger equation would demonstrate that they must have the same physics. And there is no reason to suppose that such worlds exist. >> > > There is: how do quantum computers work unless the wave function, and all > its superpositional states, are "really real"? > Quantum computers, since they rely on interference between quantum amplitudes, must operate in one world. There can be no interference between separate worlds. The old idea that quantum computer speed-up is due to all calculations being performed in parallel in other worlds has long been discarded as misguided. The idea has not even been fruitful in suggesting possible algorithms for quantum calculations. I refer you to Scott Aaronson for details. MWI is not a well-worked out theory, despite several well-known attempts. >> > > It is the most worked out quantum theory of all. It's just the Schrodinger > equation. > The trouble with that idea is that it does not work. You cannot get probabilities or the Born rule from just the Schrodinger equation. If you like, I can go through the demonstration that the Zurek derivation of the Born rule, the derivation taken up by Sean Carroll for example, is fatally circular. Similar problems exist with the Deutsch-Wallace approach using Decision Theory. It's the theories that propose collapse which aren't worked out, nor even > properly defined in many cases. > The Flash GRW theory is well worked out.. And it gives an excellent account of quantum physics. As with all other approaches to quantum theory, the Born rule has to be added as an additional postulate. But that is inevitable. fGRW has the great advantage that it is an inherently stochastic theory, so there is no problem introducing probabilities. 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLQENUgHO4tGNDSk6JbSPa4KJ-z27X4hup7JD1Wwz%2BNepQ%40mail.gmail.com.
