Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] Inertia?

Regarding:

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Brian
Whatcott
Sent: Thursday, November 13, 2008 7:22 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] Inertia?

At 11:11 AM 11/12/2008, Bill Nettles, you wrote:
...In the bending of starlight around massive stars, are the shorter
wavelength photons bent more than longer, or is the bending the same
for all wavelengths?

Thanks,
Bill Nettles
Union University

I suppose that the higher energy photons are bent more, using that
old didactically discredited equivalence of energy and mass.


Brian Whatcott Altus OK Eureka!


All wavelengths are bent the same amount if the have the same impact
parameter. The photon's energy is irrelevant as long as that energy
remains a tiny fraction of the rest energy of the gravitating star,
(which is a pretty good approximation for all the photons I know of).
Also we don't want the photon's wavelength to be so large that its
wavelength is a significant fraction of the star's radius, otherwise
wave diffraction effects would become relevant. Barring these two
extreme cases, the photon's energy is irrelevant.

David Bowman