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A black hole is a localized singularity that forms from a collapsing star. Once the star uses up its fuel, its spent energy is not enough to balance its own gravity, and it begins to collapse in on itself. When it is dense enough, its gravity is so strong that even light cannot escape its pull, and the boundary from which light cannot escape is called the singularity’s event horizon. Jacob Bekenstein suggested this event horizon is a measure of the black hole’s entropy, meaning that black holes ought to emit radiation because entropy should always be increasing, which also led to the realization they must shine, although we cannot see them. Black holes themselves cannot be directly observed, though scientists can observe their effects on surrounding material.
Black hole Quotes in A Brief History of Time
The A Brief History of Time quotes below are all either spoken by Black hole or refer to Black hole. For each quote, you can also see the other terms and themes related to it (each theme is indicated by its own dot and icon, like this one:
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Chapter 6
Quotes
The hostility of other scientists, particularly Eddington, his former teacher and the leading authority on the structure of stars, persuaded Chandrasekhar to abandon this line of work […] However, when he was awarded the Nobel Prize in 1983, it was […] for his early work on the limiting mass of cold stars.
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Chapter 7
Quotes
[…] one evening in November that year, shortly after the birth of my daughter, Lucy, I started to think about black holes as I was getting into bed. My disability makes this rather a slow process, so I had plenty of time.
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Black hole Term Timeline in A Brief History of Time
The timeline below shows where the term Black hole appears in A Brief History of Time. The colored dots and icons indicate which themes are associated with that appearance.
Chapter 3
...Penrose showed that stars can collapse in on themselves to become singularities, in this case, black holes . While Penrose only talked about stars, a young Stephen Hawking saw the relevance this...
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Chapter 4
...forces are so weak compared to other forces. But gravity would be much stronger in black holes or at the big bang, and as such needs to be integrated into quantum mechanics....
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Chapter 5
...them to collapse, and it is what happens in that time, when they become a black hole , that draws general relativity and quantum mechanics together.
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Chapter 6
John Wheeler came up with the name black hole in 1969 to describe an idea that had been around for around 200 years. In...
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John Michell’s paper in 1783 first suggested the idea of black holes , though he did not use the name. He said that any star that was...
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...helped to explain this, although it took decades for the relevance to be applied to black holes and massive stars.
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...losing the mass required to remain stable. If it doesn’t explode, it will become a black hole and ultimately collapse to infinite density. That shocked Eddington but, when Chandrasekhar won the Nobel...
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...than anything else, nothing else can escape either. This area of no return is a black hole , the boundary of which is called its event horizon.
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Because time is relative, what happens at a black hole will look different to different observers, such as someone on the surface of the star...
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...must be a singularity of infinite density and space-time curvature at the center of a black hole . This is similar to the beginning of time at the big bang, but is...
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...laws of science break down at singularities, and with them, the concept of time. A black hole’s event horizon could be considered a one-way membrane, allowing things in, but not out. Anything that falls...
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...of a star is much more rapid, and what the final stationary form of a black hole would look like was an open question. Werner Israel revolutionized views on black holes by...
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Isreal thought this meant only a perfectly spherical star could become a black hole , meaning there were no black holes in reality. But Penrose and Wheeler said a...
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Black holes were proposed before they were found. In 1962, Maarten Schmidt found what is now called...
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...that we cannot see seems impossible. But Michell suggested in 1783 we can measure a black hole ’s gravitational effects on the material around it. There are examples of systems where stars...
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More black holes have been found since, and given the age of the universe, there could be more...
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There could also be much smaller black holes , with a smaller amount of matter compressed by large external pressure, probably in the...
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Chapter 7
...focused on the big bang. Around the time of his daughter’s birth, he thought about black holes and their event horizon, a not very well-understood idea at the time, as he was...
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This non-decreasing nature of black holes determines much of their behavior. Penrose agreed with Hawking, and they determined a black hole’s...
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Jacob Bekenstein suggested a black hole ’s entropy could be measured by its event horizon. As matter fell into the black...
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This maintained the law of entropy, but suggested that black holes ought to have a temperature, meaning it must emit radiation—but black holes aren’t meant to...
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...in 1973, where he met Yakov Zeldovich and Alexander Starobinsky. They convinced Hawking that rotating black holes ought to emit particles based on the uncertainty principle. When Hawking later did the mathematics...
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...the spectrum of radiation emitted would be the same as any other hot body, and black holes seemed to obey entropy. Others have since confirmed the results, and black holes are now...
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In fact, the particles emitted do not come from the black hole itself, but the supposedly the empty space just outside the event horizon. This space is...
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Positive energy emerging from the black hole would be balanced by the negative energy falling in. According to Einstein’s E=mc2 equation, energy...
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Black holes a few times larger than the sun would be much colder than the general temperature...
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Black holes from the early universe would be much smaller though, formed by irregular pressure rather than...
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...can assess background gamma radiation in the universe to calculate how common these early universe black holes are. The evidence suggests they are scarce, so the likelihood of finding and harnessing one...
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If such a black hole were to blow up near Pluto, we could detect it, but the likelihood of that...
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The theory that black holes emit radiation rubbed people up the wrong way, and was the first significant example of...
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This new idea about black hole radiation suggests gravitational collapse is not so final after all. Mass or energy lost into...
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Chapter 8
...big crunch singularity when everything collapses back in on itself, or in localized singularities in black holes . But when applying quantum mechanics, it is clear that black holes re-emit mass and...
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...again. The central portions of the star contract into dense regions, becoming neutron stars or black holes , though this is not yet fully understood. Sometimes outer parts of a star can...
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...early universe would become more uniform like our own, and how there are not more black holes dating from that early period.
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Chapter 9
Hawking had to admit his mistake. When Eddington opposed black holes , he did so because he could not admit a mistake. Others often pretend they...
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Chapter 10
...what one can observe in the universe. For example, in the interior of a rotating black hole , or a space-time where two cosmic strings move past each other really fast. These...
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...going backward in time could be considered an anti-particle going forward in time. For example, black holes “emit” particles, where one component of a particle and anti-particle pair escapes as its partner...
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Chapter 11
...the uncertainty principle and general relativity. This has already resulted in significant rethinks, such as black holes not being black and the universe having no edges. The problem is that under the...
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...as we achieve higher energy production rates. There are upper limits of energy after which black holes form just from one particle. Though scientists cannot achieve these levels of energy anytime soon,...
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Chapter 12
...such a point in a big crunch. The theory also predicts other, localized singularities in black holes . The laws of science break down at these singularities, allowing room for God to...
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