!!! Black Hole Gravity - speed of gravity

How can black holes have gravity when nothing can get out because escape
speed is greater than the speed of light?

"Aunt Buffy" wrote in news:9z5Ac.261$Mx.8@newsfe2-
gui.server.ntli.net:

How can black holes have gravity when nothing can get out because escape
speed is greater than the speed of light?



Physics FAQ:

http://math.ucr.edu/home/baez/physic...lack_gravity.h
tml

LK

Because it is their GRAVITY that pulls everything into the Black Hole.


--
Dragons Must Fly when Thread's in the Sky

www.starlords.org

"Aunt Buffy" wrote in message
...
How can black holes have gravity when nothing can get out because
escape
speed is greater than the speed of light?




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From Aunt Buffy:

How can black holes have gravity when
nothing can get out because escape
speed is greater than the speed of light?

Good question. Many researchers believe gravity "propagates" from its
source at the speed of light. If this is so, how does a black hole's
gravity 'get out' of the event horizon, apparently with total ease? oc

A recent experiment measured gravity and concluded that it travels at the
speed of light. Thus if the sun disappeared Earth would continue in its
orbit for a 8 minutes before going off on a "tangent".

So if the speed of gravity is "the speed of light" how can it escape (and
e.g. force an accompanying star to shed its material to feed the black
hole)?

Llanzlan Klazmon The 15th pointed me to
http://math.ucr.edu/home/baez/physic...ack_gravity.ht
ml

My interpretation is: "Gravity waves" that we see outside of the blackhole
were generated before the formation of the black hole and that due to the
time dilation effect take "a long time" to emerge and become noticable to
us( outside of the event horizon). Thus the gravity we are seeing outside of
the black hole now could well have been generated 10000years ago (more
likely longer ago). The gravity waves since the creation of the black hole
are not able to escape.

Am I out of my depth?



"Aunt Buffy" wrote in message
...
How can black holes have gravity when nothing can get out because escape
speed is greater than the speed of light?

"Aunt Buffy" wrote in message
newsU8Ac.4$wS4.2@newsfe6-win...

Am I out of my depth?

Yes, but you're in good company. g

"Aunt Buffy" wrote in message ...

How can black holes have gravity when nothing can get out because escape
speed is greater than the speed of light?


One answer might be that because gravitons are virtual particles, like
their cousins the virtual photons that mediate the electrostatic
force, they might not be affected by the gravitational field they
create.

The thing that I wonder about is since time slows to a near stop at
the event horizon of a black hole, how is it that the black hole
itself can move through space and change directions as it interacts
with other objects. In many cases black holes are in orbits with
stars or neutron stars. If the companion star is massive, the black
hole must move and change direction constantly as it reacts to its
companion and traces out an elliptical orbit.

Now how can the black hole, and objects that are supposedly suspended
in almost infinitely slow time on its event horizon, be at the same
time moving and changing direction in seemingly real time as the black
hole moves through space on its orbit?

Double-A

Now how can the black hole, and objects that are supposedly suspended
in almost infinitely slow time on its event horizon,
be at the same time moving and
changing direction in seemingly real time as the black hole moves
through space
on its orbit?

Double-A

And, how come a stellar mass black hole will still express exactly the
same gravity as it did prior to the collapse? That is to say, any
planets orbiting the star will be unaffected in their orbits after the
collapse... how coom ???
oc

From Aunt Buffy:

A recent experiment measured gravity
and concluded that it travels at the speed of light.

Yeah, that was the Fomalant-Kopeikin experiment. Touted as measuring the
"speed of gravity", it was a unique, roundabout way of measuring the
speed of light, nothing more, nothing lass. See-
http://www.space,com/scienceastronom...ed_030116.html

Llanzlan Klazmon The 15th pointed me
to -
http://math.ucr.edu/home/baez/physic...k_gravity.html

Hoo boy. "Fossil fields" no less. And 'virtual gravitons' (!), virtual
photons, and what else.. angels, imps, and Sky Pixies.. all to explain
how gravity 'gets out' of a black hole. Hmm..

My interpretation is: "Gravity waves" that we see outside of the
blackhole were
generated before the formation of the
black hole and that due to the time
dilation effect take "a long time" to
emerge and become noticable to
us....The gravity waves since the
creation of the black hole are not able to
escape.

Am I out of my depth?

A bit out of your tree, perhaps. But you're certainly not alone. The
mainstream does not grasp the clear distinction between gravity and
'gravity waves'. The latter should more correctly be defined as _spatial
acoustic pressure waves_ in the fabric of space, analogous to sound
waves in air (jb's protestations notwithstanding). And these mis-named
'gravity waves' DO propagate at c.

They are _related_ to gravity, and are generated by massive
gravitational events (such as a supernova detonation or a binary BH
coalescence), but they are NOT gravity.
The mainstream's void-space paradigm(VSP) precludes the
understanding of gravity as the FLOW of the spatial medium into a
gravitating mass. Whether the mass is a normal star or a black hole is
irrelevant. The VSP precludes understanding that gravity's influence is
_instantaneous irrespective of distance_ just as Newton originally
observed. And it's instantaneous with or without an intervening event
horizon.
While this may be at odds with the interpretation of GR
on the "speed of gravity", it is a fact. If it's not, and space is a
"void", then we're stuck with "fossil fields", 'virtual gravitons',
virtual photons, angels, imps, and Sky Pixies. oc

AAK.. Make that http://www.space.com/scienceastronom...ed_030116.html