On Mon, Jul 28, 2025 at 6:55 PM Brent Meeker <[email protected]> wrote:
>>>*You've just defined "unmeasured" to mean 50/50 distribution.* >> >> > *>> That's the word I used to describe a single electron if I know nothing >> about its history. If it's not a single electron but there is a beam of >> them and I send many electrons through a Stern–Gerlach magnet then I may >> conclude that whatever the origin of the beam was, it's producing electrons >> in some distribution other than 50-50.* > > > *> Exactly my point. Your 50/50 just an epistemic assumption,**which > measurement may prove wrong. * > *If I'm dealing with a single electron no measurement will ever prove me wrong. * > *> Yet if you take the UP beam from the SG and measure Left/Right the > distribution will be 50/50,* > *Yes but I didn't know it came from the UP beam from a SG, all I knew is that the electron went up, and now that doesn't matter because I've sent that electron to a SG magnet again and I've made a Left/Right measurement so now, although I know if it's left or right, I no longer know anything about up/down except that the probability is 50-50. * > *>> Rather than a definition of measurement I will give you >> something much better, an example. Producing an electron with a known spin >> state, as a piece of magnetized iron does when, thanks to the photoelectric >> effect, it's exposed to circularly polarized light; or when an electron >> passes through a Stern–Gerlach magnet.* > > > *> So which step is the example of measurement, producing an electron with > a known spin state, as when you first measure the magnetized direction of a > piece of iron before ejecting an electron from it, or when the electron > passes thru the SG* > *Both processes produce an electron with a known spin state, so both are a measurement. * > *>>> A bit of iron found in the ground is unlikely to have encountered an >>> SG.* >> >> >> *>>True, but it's not unlikely that something equivalent could have >> occurred. * > > > *That it cooled in the Earth's magnetic field? Is that what you call > equivalent to being separated in an SG?* > *Yes because that leaves a classical record, just like a SG does. * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* we1 > > -- 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 visit https://groups.google.com/d/msgid/everything-list/CAJPayv3EcqHsDN7WAD%3DyELUZS1O67HpYTbNuNc36yrhfoUY2Tg%40mail.gmail.com.
