The Pound-Rebka experiment, produced in 1959 at Harvard University, is considered to be the last of the three classic tests of General relativity. The experiment allegedly proved the existence of gravitational redshift predicted by Einstein in his theory.
In this gravitational redshift experiment a gamma ray is send through a helium bag to an iron target and a gammaray detector, which are placed below it in air. Because the iron only absorbs the gammaray at a certain wavalength, if the wavelength changes, it will not absorb it, and it will go through it and in the detector. So if the gammaray passes through the iron target and gets detected it means that it was shifted by gravity, just as Einstein predicted. (actually it doesn't mean that)
The reason why they used a helium bag was 'to minimise scattering'.
By scattering they reffer to Compton scattering which affects both Xrays and gammarays, which get redshifted in the process (but of course they forgot to mention this small detail !) This scattering is more likely to happen in air than in helium, which has a lower electron density and smaller chance of scattering.
Then, why did they leave the detector and metal target in open air ? The reason is to maximise scattering, right before the gammaray reached the metal target. So that it could be scattered all over it and maximise the chance that it passed through it and reached the detector, so that they could claim it was shifted by gravity. But of course it was not shifted by gravity, but by scattering (and by refraction). Basically, it was a classic scam, just like the other two tests of GR.
It is known that Gammarays and Xrays are prone to scattering from the Compton effect, which redshifts them. This experiment used a bag of helium to minimise scattering, but left the detector in open air. The gammaray was therefore scattered by air and redshifted from Compton effect (in addition to Vasile effect). Even if only helium was used, it would still have been scattered and redshifted. Because minimising scattering does not elliminate scattering.
Note: in this experiment the so called 'gammaray' had an energy of 14.4 keV which coresponds to an Xray ! So in fact it was a Xray, not a gammaray (another confusion made by the two relative scientists).
tardigrade.in
And Xrays can scatter and refract at the same time, as ChatGPT says:
ME:
can an xray scatter and refract at the same time ?
In this gravitational redshift experiment a gamma ray is send through a helium bag to an iron target and a gammaray detector, which are placed below it in air. Because the iron only absorbs the gammaray at a certain wavalength, if the wavelength changes, it will not absorb it, and it will go through it and in the detector. So if the gammaray passes through the iron target and gets detected it means that it was shifted by gravity, just as Einstein predicted. (actually it doesn't mean that)
The reason why they used a helium bag was 'to minimise scattering'.
By scattering they reffer to Compton scattering which affects both Xrays and gammarays, which get redshifted in the process (but of course they forgot to mention this small detail !) This scattering is more likely to happen in air than in helium, which has a lower electron density and smaller chance of scattering.
Then, why did they leave the detector and metal target in open air ? The reason is to maximise scattering, right before the gammaray reached the metal target. So that it could be scattered all over it and maximise the chance that it passed through it and reached the detector, so that they could claim it was shifted by gravity. But of course it was not shifted by gravity, but by scattering (and by refraction). Basically, it was a classic scam, just like the other two tests of GR.
It is known that Gammarays and Xrays are prone to scattering from the Compton effect, which redshifts them. This experiment used a bag of helium to minimise scattering, but left the detector in open air. The gammaray was therefore scattered by air and redshifted from Compton effect (in addition to Vasile effect). Even if only helium was used, it would still have been scattered and redshifted. Because minimising scattering does not elliminate scattering.
Note: in this experiment the so called 'gammaray' had an energy of 14.4 keV which coresponds to an Xray ! So in fact it was a Xray, not a gammaray (another confusion made by the two relative scientists).
An electromagnetic radiation has an energy 14.4 keV To which region of the electromagnetic spectrum it belongs ?
AP EAMCET 2018: An electromagnetic radiation has an energy 14.4 keV To which region of the electromagnetic spectrum it belongs ? (A) Infrared (B) Visi
tardigrade.in
And Xrays can scatter and refract at the same time, as ChatGPT says:
ME:
can an xray scatter and refract at the same time ?
Copilot
'Yes, X-rays can indeed scatter and refract simultaneously. When X-rays pass through a material, they can interact with the atoms in multiple ways. Scattering occurs when X-rays are deflected in different directions by the atoms, while refraction happens when X-rays change their path due to the change in speed as they enter a different medium. These interactions are fundamental to techniques like X-ray crystallography, which helps in determining the atomic structure of crystals.'
Last edited:
Facebook
Twitter
Instagram