Re: Balck Holes too soft
I may have spelled his name wrong sir, but I am well read on his books.
The facts and fiction of Star trek:
Black Holes and baby Universes:
And have watched a number of his tv specials.
I never said the moon would fall. You can not compare the moon to man made sat.
Yet we all may be wrong to some degree or may have miss-understood some of his statments.
therefore,
I have taken to e-mailing him with this issue and will post his reply if or when I get one.
At which time, I will gladly state if I am in error.
Thank You and good Day.
Subject: Message to Professor Hawking e-mail account
Your mail has been received and will be read and dealt with
appropriately over the next few days.
Professor Hawking very much regrets that due to the severe limitations
he works under, and the huge amount of mail he receives, he may not
have time to write you a reply.
Yours faithfully
Neel Shearer
Graduate Assistant to
Professor S W Hawking CH CBE FRS
Lucasian Professor of Mathematics
Department of Applied Mathematics and Theoretical Physics,
University of Cambridge,
Cambridge, CB3 0WA.
United Kingdom.
P.s----
for those of you who do not want blackholes to pull your ship in. I have made a file for that. You will still recieve damage if you pass across the center. smaller ships maybe distroyed by this, but the larger ships will not.
Some facts for your enjoyment:
Usually, mass is determined by the
orbital periods of the planets' satellites. Newtonian gravity combined with Kepler's third law
of motion gives: T2 = 4 pi2a3/(GM) (where T = satellite orbital period, a = satellite semimajor
axis, G is the gravitational constant, and M is the planet's mass). For Mercury and Venus,
spacecraft deflections past the planets have given precise masses.
The moon is in synchronous rotation, so that it always shows the same face to the surface of
the Earth.
he Earth is slowing down and the
Moon is getting further away. In the past, the ``day'' and ``month'' were both much shorter.
Eventually, the Earth will always keep one face towards the Moon (Like Pluto and Charon).
Most people cite the fact that in about 5-6 billion years the Sun will become a red giant star, and swell to the orbit of Venus or even the Earth in size.
Actually, even now, the Sun grows brighter and brighter as its is evolving 'off' the main sequence. In another 500 million years of this steady
increase, it will be about 10 percent more luminous. This means that the surface of the Earth will be a LOT hotter as the oceans begin to dump more
water vapor into the atmosphere and thereby increasing the terrestrial greenhouse effect. Some forecasts suggest that in as little as another few
hundred million years, the Earth's biosphere may turn very inhospitable. Fortunately, there are 'thermophylic' bacteria that live in nearly boiling
water, so again in the far future, the Earth will end its years as a host for life by being a breeding ground for bacteria. We had better not be here
when that happens.
When two large objects orbit each other, matter may be transferred from the less dense to the denser object. The more
massive, compact object "accretes" matter from its neighbor due to its greater gravitational pull. Mass transfer may result
in gravitational radiation.
From Steven Hawkings web site:
Pile enough matter into a small enough volume
and its gravitational pull will grow so strong that
nothing can escape from it. That includes light,
which travels at the absolute cosmic speed limit
of 186,000 miles per second. In a stroke of
descriptive genius, physicist John Wheeler
named these objects “black holes.” The radius
of a black hole is called the event horizon
because it marks the edge beyond which light
cannot escape, so any event taking place inside
the event horizon can never be glimpsed from
outside—in effect, the inside of the black hole is
cut off from our universe. It has even been
speculated that black holes could be pathways
into other universes. Gravity is so strong at the
center of a black hole, that even Einstein’s
gravitational laws must break down. The theory
that governs the incredibly dense matter and
strong gravitational fields at the center of a black
hole is not yet known.”
Black holes are usually thought of as
objects with such strong gravity that
nothing, not even light, can escape from
them. However, Stephen Hawking has
shown that black holes can radiate energy.
The reason goes back to quantum
mechanics and the uncertainty principle. For
very brief periods of time, matter or energy
can be created from “empty” space
because no such thing as truly empty space
exists. Hawking realized that if a
particle/anti-particle pair came into
existence near the event horizon of a black
hole, one might fall into the hole before
annihilating its anti-particle. The other
particle could then escape the gravitational
clutches of the black hole, appearing to an
outside observer as radiation.
This space-time was not flat, but was warped and curved by the matter and
energy in it. In order to understand this, considered a sheet of rubber, with a weight placed on it, to
represent a star. The weight will form a depression
in the rubber, and will cause the sheet near the star
to be curved, rather than flat. If one now rolls
marbles on the rubber sheet, their paths will be
curved, rather than being straight lines. In 1919, a
British expedition to West Africa, looked at light from
distant stars, that passed near the Sun during an
eclipse. They found that the images of the stars
were shifted slightly from their normal positions. This indicated that the paths of the light from the
stars had been bent by the curved space-time near the Sun. General Relativity was confirmed.
Consider now placing heavier and heavier, and more
and more concentrated weights on the rubber
sheet. They will depress the sheet more and more.
Eventually, at a critical weight and size, they will
make a bottomless hole in the sheet, which particles
can fall into, but nothing can get out of.
What happens in space-time according to General
Relativity is rather similar. A star will curve and
distort the space-time near it, more and more, the
more massive and more compact the star is. If a massive star, which has burnt up its nuclear fuel,
cools and shrinks below a critical size, it will quite literally make a bottomless hole in space-time, that
light can't get out of. Such objects were given the name Black Holes, by the American physicist John
Wheeler, who was one of the first to recognise their importance, and the problems they pose. The
name caught on quickly. To Americans, it suggested something dark and mysterious, while to the
British, there was the added resonance of the Black Hole of Calcutta. But the French, being French,
saw a more risqué meaning. For years, they resisted the name, trou noir, claiming it was obscene.
But that was a bit like trying to stand against le weekend, and other franglais. In the end, they had
to give in. Who can resist a name that is such a winner?
We now have observations that point to black holes in a
number of objects, from binary star systems, to the centre of
galaxies. So it is now generally accepted that black holes
exist. But, apart from their potential for science fiction, what
is their significance for determinism. The answer lies in a
bumper sticker that I used to have on the door of my office:
Black Holes are Out of Sight. Not only do the particles and
unlucky astronauts that fall into a black hole, never come out
again, but also the information that they carry, is lost
forever, at least from our region of the universe. You can
throw television sets, diamond rings, or even your worst
enemies into a black hole, and all the black hole will
remember, is the total mass, and the state of rotation. John Wheeler called this, 'A Black Hole Has No
Hair.' To the French, this just confirmed their suspicions.
As long as it was thought that black holes would continue to exist forever, this loss of information
didn't seem to matter too much. One could say that the information still existed inside the black hole.
It is just that one can't tell what it is, from the
outside. However, the situation changed, when I
discovered that black holes aren't completely black.
Quantum mechanics causes them to send out particles
and radiation at a steady rate. This result came as a
total surprise to me, and everyone else. But with
hindsight, it should have been obvious. What we think
of as empty space is not really empty, but it is filled
with pairs of particles and anti particles. These appear
together at some point of space and time, move apart,
and then come together and annihilate each other.
These particles and anti particles occur because a
field, such as the fields that carry light and gravity, can't be exactly zero. That would mean that the
value of the field, would have both an exact position (at zero), and an exact speed or rate of change
(also zero). This would be against the Uncertainty Principle, just as a particle can't have both an
exact position, and an exact speed. So all fields must have what are called, vacuum fluctuations.
Because of the quantum behaviour of nature, one can interpret these vacuum fluctuations, in terms
of particles and anti particles, as I have described.
These pairs of particles occur for all varieties of elementary particles. They are called virtual
particles, because they occur even in the vacuum, and they can't be directly measured by particle
detectors. However, the indirect effects of virtual particles, or vacuum fluctuations, have been
observed in a number of experiments, and their existence confirmed.
If there is a black hole around, one member of a particle
anti particle pair may fall into the hole, leaving the other
member without a partner, with which to annihilate. The
forsaken particle may fall into the hole as well, but it
may also escape to a large distance from the hole,
where it will become a real particle, that can be
measured by a particle detector. To someone a long
way from the black hole, it will appear to have been
emitted by the hole.
[This message has been edited by Dracus (edited 30 March 2001).]
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