Date: Tue, 2 Jun 2020 21:12:33 -0500 (CDT)
From: "Stephen A. Fulling" <fulling@math.tamu.edu>
To: Acceleration Radiation Community: ;

1) From: Bill Unruh <unruh@physics.ubc.ca>

I guess the reason I have problems with this line of argument is 
that the essence of the detector is that there must be a change 
of state of the internal degrees of freedom of the detector for 
it to be a detector, and the coupling of the field is solely to 
this change in the internal degree of freedom. The ultimate 
longer term behaviour of the detector is a scatterer of the em 
radiation comined with these changes in internal state of the 
detector. For a charged particle there are no internal states, 
and thus no change in those internal states. One could for 
example imagine the internal states are a harmonic oscillator. As 
the freq goes to zero, there is no spontaneous emission, so the 
system has no desire to prefer one state (the ground state) over 
any other, and it will randomly wander through that infinite 
internal set of states as it interacts with the field. but even 
in that limit, the emission of a photon is always associated with 
a change in state. The emission of two photons (entangled) is 
associated with the detector in the same state it started from. 
For a charged object, there is no scattering. It acts as a direct 
source of radiation. There are no internal states. There is no 
change in those internal states associated with the the 
interaction.


William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
UBC, Vancouver,BC _|_ Program in Cosmology |____ unruh@physics.ubc.ca
Canada V6T 1Z1 ____|____ and Gravity ______|_
  https://urldefense.com/v3/__http://www.theory.physics.ubc.ca

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2) From: Don Page <profdonpage@gmail.com>

Thanks for this paper.  I have a couple of questions:

In Item 21 and Eq. (16), since the switch on/off rate alpha is 
large compared with the acceleration a, why don't the 
probabilities depend more strongly upon alpha than upon a?

On another point, the formulas for the excitation and 
de-excitation probabilities given seem to be lowest nontrivial 
order (quadratic) in the amplitudes given by Eq. (5).  So how can 
this apply to the case in which the Unruh detector accelerates 
for a very long time so that it reaches thermal equilibrium and 
emits and absorbs a huge number of Rindler particles?  I would 
have thought that one would need to go to a very high order in 
the amplitudes.

Best wishes, Don