The latest method's not very different from what you imagined as
"measuring the shadow cast" except they shoot electrons, not photons, at
the protons.
https://www.sciencedirect.com/science/article/pii/S0370269303015387?via%3Dihub
https://arxiv.org/pdf/nucl-th/0508037.pdf
They're measuring a correction term in the scattering cross-section that
depends on the size of the charge distribution in the proton.
Brent
On 4/25/2020 5:25 PM, Alan Grayson wrote:
On Saturday, April 25, 2020 at 5:36:01 PM UTC-6, Brent wrote:
On 4/25/2020 3:33 PM, Alan Grayson wrote:
On Sunday, January 6, 2019 at 12:53:52 AM UTC-7, Brent wrote:
To measure small things you need comparably short
wavelengths. If you
make a photon with a wavelength so short it can measure the
Planck
length it will have so much mass-energy that it will fold
spacetime
around it and become a black hole...so you won't be able to
use it to
measure anything.
Brent
I understand the BH issue. But suppose we want to measure the
diameter of a proton and use photons of large wave length, say of
radio frequency. If we're looking for a shadow on a screen, why
won't the large wavelength leave a discernible shadow of the
proton? Or is it the back scattering we look for? Same question;
that is, why must the impinging wavelength be of comparable
length to measure a physical object of the same approximate
length? TIA, AG
If you use a wavelength that is not shorter than the dimension
you're measuring your resolution is just the wavelength. The
waves refract around the object so you can't resole edges.
Brent
That's what I was thinking; you get diffraction on the edges, which
are then not well defined. But suppose you use a short enough
wavelength to measure the diameter of a proton. How can get an actual
measurement, given the tiny diameter? How is it done? AG
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