Oceanographers Catch First Wave Of Gravity Mission's Success

On Mon, 4 Aug 2003 12:36:08 +0100, Dr John Stockton wrote:

JRS: In article , seen
in news:sci.space.science, Morenga posted at Fri, 1 Aug
2003 17:08:46 :-

You must also consider the relative densities - see my gravity3.htm.

URL for that one?

If you cannot readily locate the page from the information provided,
then ...


http://www.merlyn.demon.co.uk/gravity3.htm, right ?! :-)

Morenga wrote:
You must also consider the relative densities - see my gravity3.htm.


URL for that one?


Dr. Stockton's URL is included in his sig. From there you can find his
many pages including

http://www.merlyn.demon.co.uk/gravity3.htm

Hop
http://clowder.net/hop/index.html

Morenga wrote:

Do black holes have Roche limits?
What if two black holes of equal mass approach each other?
Could they rip each other appart? And how so as nothing is
supposedly allowed to leave the "event horizon" once it enters.

Black hole collisions have been extensively simulated due to the
relativistic effects involved. As for nothing leaving the
event horizon, see 'Hawking radiation'.


How does the grav field look like if two fluid bodies (like gas giants)
would approach each other? I mean they would not tear each other
appart but rather "flow" towards each other, right?

Gas giants aren't entirely (or really mostly) made out of fluids. The
pressure is too high so most of it is really solid.


Maybe even forming a 3rd body at their new unified center of gravity?

Also is there a computer (PD) program for multiple stellar body grav
simulations?

Greetings
Morenga



--
Sander

+++ Out of cheese error +++

Sander Vesik writes:

Morenga wrote:

Do black holes have Roche limits?
What if two black holes of equal mass approach each other?
Could they rip each other appart?

No, they will merge together to form a single big hole whose event-horizon
area is at _least_ as large as the combined event horizons of the two holes,
in accordance with the 2nd Law of Black-Hole Dyndamics. (The Three Laws
of Black-Hole Dyndamics are in exact analogy to the Laws of Thermodynamics,
with mass playing the role of "heat," the event-horizon area playing the
role of "entropy," and the gravitational acceleration at the event horizon
playing the role of "temperature.")


And how so as nothing is supposedly allowed to leave the "event horizon"
once it enters.

Simple --- they CAN'T !!!


Black hole collisions have been extensively simulated due to the
relativistic effects involved. As for nothing leaving the event horizon,
see 'Hawking radiation'.

It is highly debatable whether Hawking radiation actually "leaves" the
event horizon. (Note that in Hawking's model, it "leaves" the horizon by
"traveling backwards in time," a concept more than a little problematic!)
A model that is physically more accurate is that gravitationally-induced
particle/antiparticle pair production occurs _OUTSIDE_ the event horizon,
and the member of the pair that falls into the black hole carries "negative
energy." ("Negative energy" is _also_ problematic, but rather less so than
"traveling backwards in time"...)


How does the grav field look like if two fluid bodies (like gas giants)
would approach each other? I mean they would not tear each other
appart but rather "flow" towards each other, right?

Gas giants aren't entirely (or really mostly) made out of fluids. The
pressure is too high so most of it is really solid.

Sorry, no. The pressure may be high, but so is the temperature !!!
Very few substances are "solid" under gas-giant interior conditions ---
not even the "metallic" hydrogen in their "mantles." One does not
generally get crystal formation unless the cores approach a degenerate
state --- and even then it is not a "normal" crystal, but a "coulomb
crystal" of pressure-ionized nuclei in a sea of degenerate electrons,
much like the crust of a white dwarf star.

As for the often-misused descriptive terms "rocky" for the core and
"icey" for the mantle, they refer to their _stochiometric compositions_,
=NOT= their physical states !!!


-- Gordon D. Pusch

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