[TheForge] YAK relativity- WAY OT, or not...

[Mike Linn]

-----Original Message-----
>I must correct myself here no electromagnetic anything escapes the event
>horizon.... sorry See the Chandra observatory page..

Blackholes emit radiation called curiously enough "Hawking Radiation". The
Hawking radiation from such black holes is minuscule. The Hawking
temperature of a 30 solar mass black hole is a tiny 2?10-9 Kelvin, and its
Hawking luminosity a miserable 10-31 Watts. Bigger black holes are colder
and dimmer: the Hawking temperature is inversely proportional to the mass,
while the Hawking luminosity is inversely proportional to the square of the
mass. Depending on the mass of the hole it can emit entire particles.
Blackholes are not really black ... their sorta fuzzy..



>As far as lensing my explanation was correct, the curvature of space-time
is
>the explanation of why lensing works. But in our frame of reference light
>"curves" along the warped space-time

true


>As far as information... just what is the information to which relativity
refers?

Any usable data that could be used to communicate knowledge.

There are "things" that can travel faster than c. Think about how fast a
shadow can move.  If you project a shadow of your finger using a nearby lamp
onto a far away wall and then wag your finger, the shadow will move much
faster than your finger.  If your finger moves parallel to the wall, the
speed will be multiplied by a factor D/d where d is the distance from the
lamp to your finger and D is the distance from the lamp to the wall.  It can
actually be much faster than this if the wall is at some oblique angle.  If
the wall is very far away the movement of the shadow will be delayed because
of the time it takes light to get there but its speed is still amplified by
the same ratio.  The speed of a shadow is therefore not restricted to be
less than the speed of light.

Others things which can go faster than the speed of light include the spot
of a laser which is pointed at the surface of the moon.  Given that the
distance to the moon is 385,000 km  try working out the speed of the spot if
you wave the laser at a gentle speed.

This sort of thing can turn up in nature.  For example the beam of light
from a pulsar can sweep across a dust cloud.  A bright explosion emits an
expanding spherical shell of light or other radiation.  When it intersects a
surface it creates a circle of light which expands faster than light.  A
natural example of this has been observed when an electromagnetic pulse from
a lightning flash hits an upper layer of the atmosphere.

These are all examples of things which can go faster than light, but which
are not physical objects.  It is not possible to send information faster
than light on a shadow or light spot so faster than light communication is
not possible in this way.


mike