Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: theThinker on 15/01/2023 16:40:30

Title: Free fall of charged particles (Attn: Hamdani Yosuf)
Post by: theThinker on 15/01/2023 16:40:30

It seems no one has done any free fall experiments for charged particles like electron, proton, charged ions. I'll like to seek the attention of Hamdani Yusuf as he posted some  comments about single photon experiments.

I'll like to know if it is possible to design an experiment to determine the free fall, say of a single electron in vacuum. Let's say we don't need high accuracy, just 15% accuracy. We create a high vacuum cylindrical chamber made of concrete/ceramic diameter 2m, height 5m. We try to eliminate electrical disturbance somehow and drop a single electron from the top middle of the chamber hoping any electrical disturbances would be minimized as the electron may be "far" from the surface of the chamber sides.

Is such an experiment possible? Is there a way to time the free fall of such an electron? 

Title: Re: Free fall of charged particles (Attn: Hamdani Yosuf)
Post by: alancalverd on 15/01/2023 17:40:39

Easy enough in principle. Make a  very long cathode ray tube and measure the change in height of the bright spot as you increase the accelerating voltage.

I did calculate it once for a 400 kV accelerator with a 5 m horizontal flight tube, and the answer was "not a lot".

Fortunately Galileo saved us the effort in his reductio ad absurdam gendankenexperiment. in Dialogo sopra i due massimi sistemi del mondo (1638).

How's that for multiculturalism?

Title: Re: Free fall of charged particles (Attn: Hamdani Yosuf)
Post by: evan_au on 15/01/2023 20:26:05

The LHC is doing an experiment to measure the free-fall speed of anti-Hydrogen.

It's very hard to measure free-fall speed for charged particles, because electrostatic forces are much stronger than gravitational forces, and any stray electrical field will destroy the experiment.
https://home.cern/news/news/experiments/new-antimatter-gravity-experiments-begin-cern

Title: Re: Free fall of charged particles (Attn: Hamdani Yosuf)
Post by: alancalverd on 15/01/2023 23:17:05

But there's little point in doing so as g = g for all massive entities.

Back to Galileo.

Suppose g_electron < g_proton . Make a hydrogen atom. Does the electron slow the fall of the proton, or does the proton accelerate the fall of the electron? Add some neutrons. Does any atom fall faster than any other?

Note for nitpickers: g is the acceleration towards the barycenter, so it's true for any object, however massive,  that you lifted from the planet.