Black Holes

Introduction

Black holes are basically a point where so much mass has collected in one small point that not even light can escape it's gravity. This is why when pictures are taken of black holes only the area the black hole is effecting can be seen, because no light be reflected nothing escapes. With all of this mass collecting in one small point, many phenomenons occur and physics as most people know them become distorted, such as the perception of time. While some think that black holes are too strange to exist there is proof and their study has led to the understanding of how our universe really works.

Formation

W020090106326416288299.jpg A Black hole is created in the aftermath of a gravitational collapse. A gravitational collapse is when a star reaches it's end and collapses into itself do to a lack of energy. At the end of these implosions small to mid sized stars can become white dwarfs or neutron stars by finding some center or force to oppose the gravity, but for massive stars that have to much gravity their collapse becomes infinite and they become Black holes.





Properties of a Black Hole

Black holes do not actually have as much gravity as most people think, because the Black hole only have as much mass as the core of a667_431.jpgstar had when it collapsed. Black holes actually rely on their size to suck in light. When it is said that a Black hole is small that is an understatement. Black holes are infinitely compressed becoming a singularity, an object which has no height, length or width, only position. This concept is hard to imagine and the phenomenons it produces are even harder to understand, such as the event horizon. The event horizon is the point of no return, an area surrounding the black hole were even light cannot escape. Some theoretical physicists have deduced that this is not directly related to gravity but by curvature in space time created by a singularity that makes falling into the black hole inevitable. Things get even more theoretical when mathematicians try to predict what an object entering the event horizon would appear like to an outside observer. Basically the observer would never see the object reach the black hole, instead he would only see an moving slower and slower towards the event horizon but never reaching it. There are two explanations for this phenomenon: one answer is that the black holes ability to suck in light creates an optical illusion with light taking longer and longer to reach the observer the closer the object gets to the event horizon. The second answer is that time actually does go slower near the black hole due to the intense curvatures in space time created by the singularity.

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How do we know Black holes exist?

Because Black holes do not reflect light and thus cannot be seen, many ask how is it that we have proof of their existence. One way we know black holes exist is because while we cannot see the actual black hole we can see the matter orbiting towards it. NASA has many pictures of rocks and debris heading towards a pit of absolute black. Scientist can also use equipment to detect X ray emission black holes induce when absorbing matter that ionizes. Because the X rays do not cross the event horizon scientists can still detect them.


Neutron Stars and Pulsars

Introduction

Neutron stars are one of the possible ends for a star the other possibility is a Black Hole. They result from massive stars that have mass greater than 4 to 8 times more than are own sun if you shrank a Neutron star to the size of the earth one teaspoonful would weigh a billion tons. Because of its small size and high density, a neutron star possesses a surface gravitational field about 2 x 1011 times that of the Earth. After these stars have finished burning their nuclear fuel, the star will then with an explosion so powerful we call it a supernova explosion.

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Escape Velocity

A escape velocity is just the speed the energy needs to escape the atmosphere. The escape velocity is very fast but not as much as a Pulsar the escape velocity is 100,000 km/s, which is about one third the speed of light. A black holes escape velocity is infinite.

Formation

After these stars have finished burning their nuclear fuel like the hydrogen, the star will then with an explosion so powerful we call it a supernova explosion. This explosion blows off the outer layers of a star into a beautiful supernova remnant. The central region of the star collapses under gravity that has wanted to collapse the star since the very beggning but the star had the hydrogen and other particles to keep up the star. After the star runs out of energy it collapses so much that protons and electrons combine to form neutrons. Which holds the star together that’s why they are called "neutron stars".

Pulsars and Neutron Star Look a like


Pulsars are another version of neutrons stars Pulsars are highly magnetized, rotating neutron that emit a beam of electromagnetic radiation. Pulsars appear to pulse because they rotate. Pulsars are spinning neutron stars that eject of particles moving almost at the speed of light they eject from the two magnetic poles on each side. Just like the north and south poles on earth. The jets move as the pulsar moves. We see the pulsars turn on and off this is only the illusion of the pulsars poles moving over the earth. The pulsar gets it energy from the rotation. Neutron stars have a gravitational field at the surface of the star is about 2 × 1011 times stronger than Earths. The escape velocity is about 100,000 km/s, which is about one third the speed of light. Such a strong gravitational field acts as a gravitational lens and bends the radiation emitted by the star such that parts of the normally invisible rear surface become visible. The force of the gravity is so strong that if an object such as a feather or a pillow were to fall from just one meter high it would only take one microsecond to hit the surface of the neutron star
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Conclusion

In conclusion Black holes and neutron stars serve to show us how little we know about our universe. The idea that our perception of time can ripped in half, metaphorically and literally is more then enough reason to keep studying these things that should belong in science fiction book. And who knows some people think that maybe black holes and neutron stars might be our best chance for discovering time travel. backtothefuture.png











References

  1. http://cosmology.berkeley.edu/Education/BHfaq.html#q10
  2. http://antwrp.gsfc.nasa.gov/htmltest/gifcity/bh_pub_faq.html
  3. http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html
  4. http://www.aei.mpg.de/einsteinOnline/en/elementary/blackHoles/pulsars/index.htm
  5. http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html