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Science homework help: Black Holes?

Science homework help: Black Holes? Topic: Science homework help: Black Holes?
July 18, 2019 / By Arny
Question: 1. Who is Stephen Hawking, and what did he do/say in 1974, which contributed to the understanding of black holes? 2.When does gravity get an "upper hand" in a stars configuration? 3. Give a brief description of a Miniature Black Hole. 4. In what year, and who (2 scientists) first suggested the existence of an "invisible" star? 5. Which double star system first suggested the existence of a Black Hole? Thank you!
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Best Answers: Science homework help: Black Holes?

Unice Unice | 8 days ago
1) Stephen Hawking is an English theoretical physicist and cosmologist, he stated that: any black hole is fully described by the three properties of mass, angular momentum, and electric charge. 2) when a star runs out of nuclear fuel, gravity gets the upper hand and the material in the core is compressed even further 3) Miniature black holes have event horizons as small as the width of an atomic particle and might have been created during the Big Bang, the moment the universe was created 4) late 1790s, John Michell of England and Pierre LaPlace of France suggested the existence of an "invisible star." They calculated the mass and size — which is now called the "event horizon" — that an object needs in order to have an escape velocity greater than the speed of light. 5) Cygnus X-1 is one of the most likely candidates to date. First detected as a source of x-ray radiation in 1965, how was it detected? A way to detect a black hole in a binary system is by observing x-rays generated around it. Normal stars are not high emitters of x-rays, energetic radiation with wavelengths much shorter than visible light
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Unice Originally Answered: [Physics] What do black holes do?
A black hole is, by definition, a region in space time in which the gravitational field that it precludes even light from escaping to infinity. They usually occur when a star has become so massive that its gravitational field actually causes it to collapse into what is called a singularity, a single point in space that has a huge density and gravitational pull. Black holes cannot be seen because of the fact that they actually pull light into them so they are located where there is an apparent blank spot in the sky. Check out this link: http://books.google.ca/books?id=n0kHI6CVWZUC&dq=black+hole&printsec=frontcover&source=bl&ots=9cJIjk_ivQ&sig=iEGFbeovDDwmE9FE80mtAYm1MKs&hl=en&ei=_zfuSrifMMbulAePye3_BA&sa=X&oi=book_result&ct=result&resnum=16&ved=0CDwQ6AEwDw#v=onepage&q=&f=false

Sariah Sariah
1) Stephen Hawking is an English theoretical physicist and cosmologist, he stated that: any black hole is fully described by the three properties of mass, angular momentum, and electric charge. 2) when a star runs out of nuclear fuel, gravity gets the upper hand and the material in the core is compressed even further 3) Miniature black holes have event horizons as small as the width of an atomic particle and might have been created during the Big Bang, the moment the universe was created 4) late 1790s, John Michell of England and Pierre LaPlace of France suggested the existence of an "invisible star." They calculated the mass and size — which is now called the "event horizon" — that an object needs in order to have an escape velocity greater than the speed of light. 5) Cygnus X-1 is one of the most likely candidates to date. First detected as a source of x-ray radiation in 1965, how was it detected? A way to detect a black hole in a binary system is by observing x-rays generated around it. Normal stars are not high emitters of x-rays, energetic radiation with wavelengths much shorter than visible light Thanks Richard.
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Nora Nora
1. Stephan hawking is an english theoretical physicist and cosmologist. Hawking's has provided theorems regarding gravitational singularities in the framework of general relativity, and the theoretical prediction that black holes should emit radiation, which is today known as Hawking radiation. 3.Micro black holes are tiny black holes for which quantum mechanical effects play an important role. It is possible that such quantum black holes were created in the high-density environment of the early Universe or big bang, or possibly through subsequent phase transitions. They might be observed by astrophysicists in the near future, through the particles they are expected to emit by Hawking radiation. 4.The invisible stars that Jesse Bregman mentioned are not actually invisible, they're just invisible to us. These stars are like the ordinary stars you see in the sky. They give off light and they are formed in the same way and from the same materials as ordinary stars. The invisible stars Jesse mentioned are only invisible to us because they are behind or embedded in thick clouds of gas, dust, and ice. Couldnt find anything else on question 2 and 5
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Mabel Mabel
1. I think you're referring to Hawking's famous paper "Black Holes are White Hot" which resulted in the coining of the term Hawking radiation to describe the decay of black holes. 2. A star has to be of a certain mass and size to collapse in on itself and form a black hole, this is known as the Chandrasekhar limit if the star is bigger than this limit gravitation will run unchecked and it will collapse in on itself and become a black hole. The radius a star of mass M has to be before light itself cannot escape is called the Schwarzschild radius. 3. A miniature black hole sometimes called a goblin (which star trek fans will know as a quantum singularity) or micro black holes or mini black holes, or quantum mechanical black holes are all names for a theoretical construct of cosmology and quantum mechanics which is unimaginably dense and has such a strong gravitational influence beneath the event horizon that light itself can't escape. Hawking postulated that such tiny black holes will decay by a process that has become known as Hawking radiation, whereas on the event horizon the gravitational forces are strong enough to rip nothing apart into a photon and an anti-photon, the anti-photon is captured and enters the black hole whereas the photon escapes into our universe, the black hole then becomes a little lighter. Some believe these micro black holes will be remnants of the big bang others that they may form spontaneously due to random fluctuations in mass as described by quantum mechanics. 4. John Michell of England and Pierre LaPlace of France ( they were not collaborating but came to the conclusion separately). This was sometime in the 1790s. 5. I think that was Cygnus X-1 first discovered in 1964 and became famous for being a black hole when it appeared on the BBC science fiction series Blake's Seven. It forms part of a binary star system and was the brightest x-ray source discovered at that point.
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Kell Kell
1. A pro BMX rider/physicist who sent cameras into black holes to take pictures of the alternate dimensions. In one, I'm a T-Rex with a top hat and monocle. 2. August 21, 2115. Then and only then. 3. Your mom. 4. 2854 by Chuck Norris and David Caruso, who in the future will be the top scientists on both Earth and Mars. They traveled back in time to let us know about invisible stars next year, until then they have their film careers. 5. DOUBLE STAR!!! THAT'S WAY BETTER THAN DOUBLE RAINBOW!!!
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Irma Irma
Reality is that even if someone gives you the right answers you will be better informed but none the wiser.
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Elfa Elfa
Sorry, I'm not sure You can't possibly learn anything if you have other people do homework for you. However, it may help to give you a hint: Google.
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Elfa Originally Answered: How do we know black holes exist?
We cannot actually photograph a normal black hole because black holes absorb light and they are not visible. That's why we call them black. However, scientist can photograph the supermassive black hole at the core of our galaxy, as a supermassive black hole is large and becomes visible (leaves a 'shadow') when it starts feeding. Gas trapped in it's accretion disk becomes so hot (as it spins with almost the speed of light) that it gives out extremely bright light This is not something very easy because it is far away and it's difficult because the core is dense with stars and we cannot get a clear view of it. The biggest problem actually is that we don't have a telescope that large needed to take a photo of the black hole. For this to happen, scientist started a project called the Event Horizon Telescope that basically links all major telescopes around the world and make a virtual telescope as large as the US itself. That would tehnically solve the distance an clarity issues. The network is partially complete as we have some preliminary photos. They obtained a modelled black hole shadow (left) and two simulated observations of the supermassive black hole in the middle of our galaxy using a 7-telescope and 13-telescope array (Fish & Doeleman) So I give you Sagittarius A* ( the supermassive black hole in our galaxy core): http://www.astroengine.com/wp-content/up...

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