On 4/26/2020 3:22 PM, Alan Grayson wrote:


On Sunday, April 26, 2020 at 1:46:59 PM UTC-6, Brent wrote:



    On 4/26/2020 9:24 AM, Alan Grayson wrote:


    On Sunday, April 26, 2020 at 9:48:45 AM UTC-6, John Clark wrote:

        On Sat, Apr 25, 2020 at 12:49 PM Alan Grayson
        <[email protected]> wrote:

            /> How does QM tell us that conservation of energy can be
            violated for brief durations? If you apply the
            time-energy form of the UP for your proof, please state
            the context of your proof, that is, exactly what do E and
            t stand for./


        The shorter the time (t) a system is under observation the
        larger the amount of energy (E) could pop into existence from
        nothing without direct detection, enough energy to create
        virtual particles. And you can calculate how large the
        indirect effects these virtual particles would have on the
        system.


    As I understand the UP, it's a statistical statement about an
    ensemble of observations, say for position and momentum of
    identical particles. It says nothing about the result of events,
    say for the position and momentum of a single particle or event.
    Doing some arithmetic to get the time-energy form of the UP does
    not change this reality. As a result, your description of what
    happens to a single particle, virtual or not, is not
    intelligible. Please try again. AG

    The UP doesn't apply to virtual particles because it refers to the
    result of conjugate measurement (projection) operators.  You can't
    measure virtual particles.

    Brent


In its usual form, does the UP allow us to measure position and momentum *simultaneously*, or must we measure each variable independently (for an ensemble of identical particles, of course)? What is proper interpretation of the time/energy form of the principle in statistical terms? TIA, AG

You can measure them simultaneously; but when you repeat the pair of measurements on many identically prepared particles you find that there is a scatter in the position  and a scatter in the momentum such that the HUP is satisfied.

Brent

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