Transcript Black Holes: Vacuums of the Universe

Black Holes:
Vacuums of the Universe
• By Micah Burgdorf
• vesc = (2GM/R)1/2
Gravity
• Gravity is the attractive force that all matter
produces that pulls toward it other matter.
• Gravity is the basis of a blackhole without The
measure of the force of gravity depends upon the
mass of an object.
• Mass is sort of like the weight of an object, but
without the Earth’s own gravitational pull on the
object.
Creation
• There are two forces
working in a star,
gravity and explosions.
• When the fuel runs out
in a massive star (say 3
times the mass of our
own Sun), the star
explodes in a supernova
(a gigantic explosion).
Creation
• The supernova on the outside hides the
implosion happening on the inside
caused by the gravity.
• The gravity pulls all the matter back
into the center only much more dense.
• The decrease of the size of the matter
increases the density to the point that
space time becomes bent, as in the
diagram.
• Space-time forms a hyperbola in the
presence of a black hole.
Warps in Space-Time
• All matter can create a
warp in the space-time
continuum due to their
gravitational field.
• Even our own Sun
warps space-time, but
since it is less dense
than a black hole it can
not puncture it.
Space-Time Continuum?
• Best if I start at the beginning (not the big bang, that's
later). I'm sure you've heard the much bandied about
description of this universe wrapped up with the neat
little label ‘space time.’ I'm going to ask you to imagine that
we're living in a two-dimensional world just like living in a
piece of paper. Why? See, space time for a three
dimensional world plus the time dimension is a 4D shape,
which, understandably, humans have a tough time picturing.
Space time for a 2D universe like that paper would be a 3D
thing, which I can describe to you rather well (if I do say so
myself!). Thus, please, don't tax my poor brain by asking me
to describe anything higher than three dimensions.
Space Time Continuum?
• So, we've got this infinite 3D jello-mold of the universe, here, to
serve as my analogy (wobble, wobble). Let's take a slice--schlok! What does this slice represent? This is the shape of
space time at a certain time. See, over there is a star---see how
the jello bends down? Over yonder is a black hole---look at the
point on that sucker! See, there, that double-bumped dip is a
binary system. These dips in space time are called gravity wells.
The presence of matter or energy (lots and lots of energy) warps
space time. Anyway, when space time bends, it manifests as
something we call 'gravity.' The more stuff, the more bend. The
more bend, the more gravity. If you get enough stuff within a
certain area, you pop! right through the jello slice and get a black
hole.
Why are They Black Holes?
• It is said that black holes
have such strong gravity
that not even light can
escape one.
• Yet light has no mass to be
attracted by the black hole.
• It is the warp in Space-Time that captures light. The
warp transforms all straight lines into curved lines.
Why are They Black Holes?
• So the straight path that light follows
becomes curved, some rays become
stuck in an orbit (Photon Sphere).
• In the pictures to the right you see an
actual star (the medium sized dots)
and their images (the smaller dots).
• These images are made from the light
of the stars moving toward the black
hole are sent around the black hole
(the large dot).
Warped Physics
• When one reaches the Event Horizon (not the
terrible movie, but the radius in which nothing
not even light can escape its warp), all of the
normal laws of physics will be thrown out the
window.
• For these conditions new equations need to be
created. For this position physicists such as Karl
Schwarzchild, Reissner-Nordstrom, and Kerr.
• We’ll go into them later.
Karl Schwarzchild
• Before we get into the most basic type of black
hole, I would like to introduce Karl Schwarzchild.
• Karl Schwarzchild created the Schwarzchild
Radius. This radius, described by the formula
Rs=GM/c2, is the position of the event horizon.
Where G is the gravitational constant, M is the
mass of the Black hole, and c is the speed of light.
Static Black Holes
• Static black hole have only
one event horizon and one
photon sphere.
• There’s nothing out of the
ordinary with this class.
• The event horizon is one
Schwarzchild Radii from the
singularity. While photon
sphere exists 1.5 Radii from
the singularity.
Charged Black Holes
• Charged- Instead has
Two event horizons! In
between the two one
can move forward and
backward through time
as easy as walking.
• Since this has a charge
we must consult
Reissner-Nordstrom.
Reissner-Nordstrom
• According by ReissnerNordstrom the two event
horizons are a result of the
charge.
• Now here is the interesting
part, as the charge grows
and approaches the mass of
the black hole the event
horizons begin to merge together.
When the charge exceeds the mass the event horizons
disappear! This means that something would be able to move
in and out at will.
Rotating Black Holes
• Rotating black holes
have two event horizons
and Two Photon
Spheres! The second
sphere and horizon is
created by the dragging
of space-time behind the
black hole as it spins.
• But there is also
something called the
Ergosphere.
Ergosphere?
• The outer boundary of the ergosphere
is the static limit of the rotating black
hole. What's a static limit? It's where
you can no longer stay still, even if you
were going at the speed of light. For
static black holes the static limit is the
event horizon, since after you cross that,
even if you go the speed of light, you are
pulled towards the singularity.
However, you can enter and leave this region whenever you like, unlike the
abandon-all-hope-ye-who-enter-here static limit/event horizon of the other two
black holes. You can merrily weave in and out of the ergosphere with no nasty
side-effects. It's a place of quirky space time of the black hole that we can
actually visit and leave.
How Can We be Sure?
• We can be sure that
blackholes exist not
only for the fact of
mysterious eclipses of
stars or that strange
images, but also some
massive stars have
been seen orbiting
invisible objects.
Uses
• If humanity should ever actually
reach a black hole there are
speculations as to the possible uses
for such a phenomenon.
• A black hole could be used as a
dumpsite or there are theories to
use it as an immense power source
since it contains a great deal of
compressed atoms. There is even talk that a black hole can
be used as an inter-dimensional gateway. This would make
definate use of a charged black hole.
Bibliography
• For more information try these sites:
• <http://www.physics.syr.edu/courses/PHY3
12.985pring/projects/jebornak/>
• <http://archive.ncsa.uiuc.edu/Cyberia/Num
Rel/EinsteinTest.html>
• <http://casasrv.colorado.edu/~ajsh/home.ht
ml>
• Now I think your brain deserves a rest.