How does Stephen hawkings explain the singularity
Question
How does Stephen hawkings explain the singularity
Solution
Stephen Hawking, along with Roger Penrose, applied the mathematics of black holes to the entire universe and developed the Penrose-Hawking singularity theorems. These theorems provided a set of sufficient conditions for the existence of a singularity in space-time. This work shows that singularities are not merely the peculiar properties of the special relativistic cosmological models, but can also appear in the general theory.
In simple terms, a singularity is a point in space or spacetime where some physical quantities become infinite or undefined. In the context of black holes, a singularity is the core with an incredibly high gravitational force where space and time become infinite and the laws of physics as we know them cease to operate.
Hawking also proposed the idea of the universe having no singularities in the "no-boundary proposal" or "Hartle-Hawking state". This model proposes that if we could travel back in time towards the beginning of the Universe, we would note that quite near what might have otherwise been the singularity, the laws of physics would have begun to change, the Universe would have begun to smoothly contract, and this would continue indefinitely.
So, in essence, Hawking's work on singularities is twofold - he showed that under certain conditions, singularities are inevitable. But he also proposed a model of the universe that avoids the problem of the singularity at the beginning of time.
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It can be inferred from the first paragraph that Hawking radiation puzzled Stephen Hawking because:The radiation from the black hole reconciled general relativity with quantum mechanics.The radiation from the black hole confirmed that information is neither lost nor created.The radiation from the black hole carried no information about its past or future.The radiation from the black hole ensured the certainty of an event within the scope of all possible outcomes.
Hawking’s discovery of the Hawking radiation, possible through thought experiment, brought general relativity and quantum theory together in a remarkable way. But Hawking was puzzled by features of this radiation – or more precisely, its lack of features. Critical to the probability interpretation of quantum mechanics was that something always happens. If you add up the probabilities for anything that may happen, you will find that the total probability is one. This can be formulated as a statement about information: if one knows everything one can know about a system at one time, one can know everything about it at later times. But this did not seem to be the case for radiation from black holes.These ideas may be unfamiliar – so it is worth elaborating a bit. If you enter a lottery and buy one ticket and there are 10 million lottery tickets sold, your chances of winning the jackpot are 1 in 10 million. But you either win or lose the lottery: the chance of winning or losing is 100 per cent.What does it mean for information to disappear? Of course, we all forget things… but we believe that we could, in time, reconstruct this information. The amount of information in a system doesn’t change, though it may be hard to access. For a system, like a collapsing star, there is a lot of information. …Thanks to Hawking, we know that it forms a black hole and then slowly evaporates, emitting radiation. The information that was contained in the initial star has been reduced to just the temperature of a warm body. Hawking argued that the information was simply lost. Quantum mechanics, he asserted, breaks down near black holes.Many leading theorists have struggled to resolve the puzzles raised by this thought experiment. Some have argued that, one has to redo quantum mechanics or general relativity to resolve Hawking’s paradox. Others have been more sceptical. Perhaps, the evaporation of a black hole is like a lump of ash from the burning of a log. Surely, the laws of quantum mechanics don’t break down when an object burns? In that case, the resolution of the puzzle is that the outgoing radiation is not exactly that of a black body because subtle connections between the outgoing photons remain intact. But it was soon realised that the answer could not be so simple; the structure of space and time makes it hard to understand how such correlations might arise. … Perhaps Hawking was right: just as Newtonian physics was usurped by quantum mechanics and general relativity on large or tiny scales, something had to give here as well.It turns out that there is a situation where black holes could exist and quantum mechanics could make sense: string theory. String theory, also emerging from thought experiments, replaces the particles of quantum mechanics with one-dimensional strings. That concept has provided at least a partial resolution of the puzzle. Two theorists at Harvard University – Cumrun Vafa and Andrew Strominger were able to understand the temperature of certain idealised black holes in quantum mechanical terms. In other words, the information, at least for these idealised systems, somehow survives, evading Hawking’s paradox.
In 1964 the Nobel Laureate Roger Penrose established the mathematical theory to describe how a black hole could exist. He derived his theory from Albert Einstein’s general theory of relativity and demonstrated that the formation of black holes was a natural process in which a supermassive object accumulates a gravitational force so great that nothing, not even light, can escape it. More perplexing, Penrose explained that at the center of a black hole as a singularity at which all known laws of nature dissolve. Which choice best states the main idea of the text?Choose 1 answer:Roger Penrose used mathematical theory to describe properties of black holes and demonstrate how black holes are formed.eliminateRoger Penrose described a novel mathematical theory based on Albert Einstein’s work.eliminateBlack holes are supermassive objects with a central singularity at which all known laws of nature dissolve.eliminateBefore Roger Penrose, no physicist was able to describe a mathematical theory to explain how black holes are formed.
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