On 5/29/2014 8:44 AM, Robert L. Oldershaw wrote:
On Wednesday, May 28, 2014 2:18:37 AM UTC-4, Phillip Helbig---undress to reply wrote:
Consider how long it takes a photon to get from the core to the surface
of the Sun. I don't recall the number, but it is 1 million years or
so.

But I think that electromagnetic and gravitational interactions
between the inner core of the Sun and its convective layers take a
good deal less time than a million years.

EM? Perhaps you are thinking of an oscillating magnetic
dipole with a frequency of 22 year^(-1), i.e. flipping
every 11 years, which has its source in the center?
But it will have it's field strongly attenuated by the
conducting medium around it. The field changes we are
talking of are now still photons, but with a very low
frequency.

Basically the attenuation length for EM waves applies
here, which is the "skin-depth" in the medium at this
frequency. For EM communication from the center to the
surface we need 10^8 to 10^9m for this skin-depth:
delta = sqrt(2/omega sigma mu)
If we assume mu=mu0 (non-magnetic medium) this is the
same as requiring:
sigma 0.001 [S/m]
But I would expect the plasma to conduct much better
(may astrophysicists here correct me if I'm wrong).

So EM communication would seem to be impossible. And
for the gravitational interaction you mention, you'd
need gravitating density fluctuations in the core, i.e.
quite strong ones. But in that case, shouldn't we also
look at simple pressure waves (sound) as the mechanism?

--
Jos