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  • Re: Want to prove E=mc?? University labs should try this!

    From J. J. Lodder@21:1/5 to rhertz on Sun Nov 17 22:15:57 2024
    rhertz <hertz778@gmail.com> wrote:

    Current "state of the art" weighting technology (expensive) can measure
    about 1 nanogram of MASS.

    So your ignorance of physics extends to experimental technique as well.
    FYI, comparing standard kilograms can be done at present to about 10^-9,
    so to microgram accuracy.

    I asked ChatGPT this question:

    Why, for heavens sake? To dumb to think for yourself?

    But one can easily estimate orders of magnitude:
    c^2 = 9x10^16 joule/kg, so at 10^-9 accuracy
    you need to add 9x10^7 joules to a standard kg
    for it's relativistic mass increase to be detectable.
    This is about 20 kg of TNT equivalent.

    So for the kiddies: don't try this at home,
    (and draw your own conclusions)

    Jan

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  • From J. J. Lodder@21:1/5 to Tom Roberts on Wed Dec 11 23:22:53 2024
    Tom Roberts <tjoberts137@sbcglobal.net> wrote:

    On 11/23/24 1:12 AM, ProkaryoticCaspaseHomolog wrote:
    [...] Of all the schemes I could think of whereby a DIY amateur scientist can verify E=mc?, the only feasible one that I can think of is to
    measure the energy of electron-positron annihilation.

    You'll need a budget of at least $10,000.00 (probably more), and I doubt
    you could obtain a useful resolution (say, 1%).

    I'd need
    the help of an expert former EE to put things together (hint, hint).

    Or better, the assistance of an experimental particle physicist. But it
    would be quite difficult to interest someone with the requisite
    skills.... I have those skills, but am not interested.

    Sealed sodium-22 positron sources are readily available for sale
    online.

    Yes. But I don't know if they will sell to an unaffiliated DIY
    experimenter. Sales of radioactive objects are often restricted, and
    they are usually prohibited in standard delivery channels (UPS, FedEx,
    USPS, ...).

    Calibrating the gamma-ray detectors will be the hard part.

    Yes. You'll need several different gamma sources with known emission energies.

    Once
    calibrated, I'd place two gamma-ray detectors 180 degrees apart
    equidistant from an appropriate target. Connected to the detectors
    will be a whole slew of equipment for coincidence counting, energy measurement, etc. that the expert former EE will be responsible for.

    With luck, the DIY experimenter will be able to confirm the
    simultaneous emission of two 511 keV photons from each annililation.

    This is certainly doable. Whether it is worthwhile is a quite different
    issue -- personally I doubt it.

    Note: this is the sort of experiment that could be in the syllabus of
    the appropriate undergraduate lab class at a good college or university. (They would use the equipment for several different experiments and many students.)

    Yes, but even if you could do it perfectly it is still an error
    to claim that E=mc^2 has been verified.
    Excercise for the kiddies: what does such an experiment verify nowadays,
    (if anything)

    Teaching them to interpret experiments correctly
    is perhaps more useful than having them pottering about,

    Jan

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