Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: jeffreyH on 17/03/2017 12:47:48

Title: How would a particle accelerate in a gravitational field?
Post by: jeffreyH on 17/03/2017 12:47:48

If we have a large mass, maybe earth size, in a vacuum with one particle travelling towards it, would it accelerate as fast as say a brick? It should since all masses fall at the same rate. If not why not?

Title: Re: How would a particle accelerate in a gravitational field?
Post by: jeffreyH on 17/03/2017 17:48:53

https://en.m.wikipedia.org/wiki/Paradox_of_a_charge_in_a_gravitational_field (https://en.m.wikipedia.org/wiki/Paradox_of_a_charge_in_a_gravitational_field)

Title: Re: How would a particle accelerate in a gravitational field?
Post by: Colin2B on 18/03/2017 09:32:20

Quote from: jeffreyH on 17/03/2017 17:48:53

https://en.m.wikipedia.org/wiki/Paradox_of_a_charge_in_a_gravitational_field (https://en.m.wikipedia.org/wiki/Paradox_of_a_charge_in_a_gravitational_field)

Also https://cds.cern.ch/record/403583/files/9910019.pdf (https://cds.cern.ch/record/403583/files/9910019.pdf)

Title: Re: How would a particle accelerate in a gravitational field?
Post by: JohnDuffield on 18/03/2017 12:28:29

Quote from: jeffreyH on 17/03/2017 12:47:48

If we have a large mass, maybe earth size, in a vacuum with one particle travelling towards it, would it accelerate as fast as say a brick? It should since all masses fall at the same rate. If not why not?

I'm sorry Jeffrey, but your question isn't quite clear. Can you clarify? 

Meanwhile, imagine that I'm in my spacesuit hanging from my gedanken spaceship near an Earth-sized planet. This planet has no atmosphere, but I have a brick in one hand, and an electron in the other. When I let them go, they both fall downwards at the same rate. When they hit the ground the brick kicks up dust and loses kinetic energy, and the electron radiates and loses kinetic energy. The electron then stops radiating. A charged particle does not radiate when its supported in a gravitational field, and it does not radiate when it falls. It only radiates when you stop it falling. Whilst you can find papers saying otherwise, such papers are not in line with the hard scientific evidence, and are wrong.   

Title: Re: How would a particle accelerate in a gravitational field?
Post by: jeffreyH on 18/03/2017 16:36:38

Quote from: Colin2B on 18/03/2017 09:32:20

Quote from: jeffreyH on 17/03/2017 17:48:53

https://en.m.wikipedia.org/wiki/Paradox_of_a_charge_in_a_gravitational_field (https://en.m.wikipedia.org/wiki/Paradox_of_a_charge_in_a_gravitational_field)

Also https://cds.cern.ch/record/403583/files/9910019.pdf (https://cds.cern.ch/record/403583/files/9910019.pdf)

I've only had time to skim through it but I will be reading all of it. Thanks for the reference.

Title: Re: How would a particle accelerate in a gravitational field?
Post by: jeffreyH on 18/03/2017 17:43:42

The finding that the electric field and charge of a freely falling particle feel no relative acceleration is the most important point of the article. It says a lot about why gravitational and inertial mass are equivalent.