- #1
Naty1
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We have talked about black hole, Unruh and cosmological horizons in these forums...I am wondering if a simple example [thought experiment] might usher in an introduction to such rather abstract horizons:
the sphercial hollow shell of matter...from the outside, a test particle is attracted just as if the shell were a point charge; but after passing thru the shell suddenly there is no gravity...the particle is suddenly no longer subject to any gravitational attractions.
For an infinitesimally thin shell, there is a discontinuous jump in gravitational potential.
This seems to have SOME similarities to the first three horizons I mentioned...for example, as a test particle approaches the hollow shell from the outside would it not appear to slow when viewed from a distant intertial frame since some time dilation occurs...increased gravitational potential. What happens to that particle's "aging" when viewed from that same distant inertial frame inside the shell? Does time continue to "slow" for that particle, so that for example, maybe a radioactive decay would appear delayed from the distant frame?? Seems like it must...Or does it resume zero gravitational behavior??
I fear I have missed something because I have never seen such a simple example discussed as an illustration of "horizons"...
Comments,insights,criticisms appreciated.
the sphercial hollow shell of matter...from the outside, a test particle is attracted just as if the shell were a point charge; but after passing thru the shell suddenly there is no gravity...the particle is suddenly no longer subject to any gravitational attractions.
For an infinitesimally thin shell, there is a discontinuous jump in gravitational potential.
This seems to have SOME similarities to the first three horizons I mentioned...for example, as a test particle approaches the hollow shell from the outside would it not appear to slow when viewed from a distant intertial frame since some time dilation occurs...increased gravitational potential. What happens to that particle's "aging" when viewed from that same distant inertial frame inside the shell? Does time continue to "slow" for that particle, so that for example, maybe a radioactive decay would appear delayed from the distant frame?? Seems like it must...Or does it resume zero gravitational behavior??
I fear I have missed something because I have never seen such a simple example discussed as an illustration of "horizons"...
Comments,insights,criticisms appreciated.
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