Can Extremal Black Holes Have Non-Zero Entropy

Black Holes 黑洞What is a black hole? Well, it's difficult to answer this question, since the terms we would normally use to describe a scientific phenomenon are inadequate here. Astronomers and scientists think that a black hole is a region of space (not a thing) into which matter has fallen and from which nothing can escape - not even light. So we can't see a black hole. A black hole exerts a strong gravitational pull and yet it has no matter. It is only space - or so we think. How can this happen?The theory is that some stars explode when their density increases to a particular point; they collapse and sometimes a supernova occurs. From earth, a supernova looks like a very bright light in the sky which shines even in the daytime. Supernovae were reported by astronomers in the seventeenth and eighteenth centuries. Some people think that the Star of Bethlehem could have been a supernova. The collapse of a star may produce a White Dwarf or neutron star - a star, whose matter is so dense that it continually shrinks by the force of its own gravity. But if the star is very large (much bigger than our sun) this process of shrinking may be so intense that a black hole results. Imagine the earth reduced to the size of a marble, but still having the same mass and a stronger gravitational pull, and you have some idea of the force of a black hole. Any matter near the black hole is sucked in. It is impossible to say what happens inside a black hole. Scientists have called the boundary area around the hole the "event horizon." We know nothing about events which happen once objects pass this boundary. But in theory, matter must behave very differently inside the hole.For example, if a man fell into a black hole, he would think that he reached the center of it very quickly. However an observer at the event horizon would think that the man never reached the center at all. Our space and time laws don't seem to apply to objects in the area of a black hole. Einstein's relativity theory is the only one which can explain such phenomena. Einstein claimed that matter and energy are interchangeable, so that there is no "absolute" time and space. There are no constants at all, and measurements of time and space depend on the position of the observer. They are relative. We do not yet fully understand the implications of the relativity theory; but it is interesting that Einstein's theory provided a basis for the idea of black holes before astronomers started to find some evidence for their existence. It is only recently that astronomers have begun specific research into black hole. In august 1977, a satellite was launched to gather data about the 10 million black holes which are thought to be in the Milky Way. And astronomers are planning a new observatory to study the individual exploding stars believed to be black holes.The most convincing evidence of black holes comes from research into binary star systems. Binary stars, as their name suggests, are twin stars whose position in space affects each other. In some binary systems, astronomers have shown that there is an invisible companion star, a "partner" to the one which we can see in the sky. Matter from the one which we can see is being pulled towards the companion star. Could this invisible star, which exerts such a great force, be a black hole? Astronomers have evidence of a few other starstoo, which might have black holes as companions.The story of black holes is just beginning. Speculations about them are endless. There might be a massive black hole at the center of our galaxy swallowing up stars at a very rapid rate. Mankind may one day meet this fate. On the other hand, scientists have suggested that very advanced technology could one day make use of the energy of black holes for mankind. These speculations sound like science fiction. But the theory of black holes in space is accepted by many serious scientists and astronomers. They show us a world which operates in a totally different way from our own and they question our most basic experience of space and time.什麼是黑洞呢？這個問題很難回答，因為我們通常用來描述一種科學現象的術語用在這裏來解釋是不夠的。

Reading: Text 11.Match the words with their definitions.1g 2a 3e 4b 5c 6d 7j 8f 9h 10i2. Complete the following expressions or sentences by using the target words listed below with the help of the Chinese in brackets. Change the form if necessary.1 symbolic 2distributed 3site 4complex 5identify6fairly 7straightforward 8capability 9target 10attempt11process 12parameter 13interpretation 14technical15range 16exploit 17networking 18involve19 instance 20specification 21accompany 22predictable 23profile3. Read the sentences in the box. Pay attention to the parts in bold.Now complete the paragraph by translating the Chinese in brackets. You may refer to the expressions and the sentence patterns listed above.ranging from（从……到）arise from some misunderstandings（来自于对……误解）leaves a lot of problems unsolved（留下很多问题没有得到解决）opens a path for（打开了通道）requires a different frame of mind（需要有新的思想）4.Translate the following sentences from Text 1 into Chinese.1) 有些人声称黑客是那些超越知识疆界而不造成危害的好人（或即使造成危害，但并非故意而为），而“骇客”才是真正的坏人。

霍金对黑洞提出全新说明Wait, so my life may not have disappeared down a black hole after all?等等，你适才是说，我可不能被黑洞所吞噬？There is a chance for it to emerge and bloom like the career of D avid Hasselhoff?It's charming when a phrase enters the language and we think we all know what it means. In the case of "black hole," we think of an infinity of black nothingness that swallows everything that slips into it. But now, in a new paper called "Information Preservation and Weather Forecasting for Black Holes," Stephen Hawking has cast the cat among the black, holey（多洞的）pigeons and cau sed a scattering of incomprehension.His precise words were: "The absence of event horizons mean that there are no black holes -- in the sense of r eg imes from which light can't escape to infinity."It seems clear. There are no forever and ever holes of blackness. There is always the chance that light might emerge.Hawking continued, however: "There are howe ver apparent horizons which persist for a period of time. This suggests that black holes should be redefined as metastable bound states of the gravitational field."So there are black holes. It's just that we should redefine them a touch. So what's this apparent horizon?Well, it's "a surface along which light rays attempting to rush away from the bla ck hole's core will be suspended."But if they're su spended, they will never emerge, stuck in solitary confinement like the Man in the Iron Mask. The result is surely still the same. Once something disappears into a black hole, it's done for.At times of existential stress like these, I turn to Nat ure magazinefor help. It suggests that, at least in theory (and, let's face it, this is all theory), black holes might at some point disappear.However, the magazine offers a dispiriting set of words from Don Page, a physicist from the University of Edmonton in Canada. It might be possible that particles could emerge from black holes, he said. Oh, cry of joy.However, if particle s did "it would be worse than tr ying to reconstruct a book that you burned from its ashes."Ah, now that's a feeling I'm familiar with.。

宇宙相关英文作文1. What is the universe?The universe is everything that exists, including all matter, energy, and space. It encompasses all galaxies, stars, planets, and other celestial bodies, as well as all the laws of physics that govern their behavior. It is vast and incomprehensible in its size and complexity, and scientists continue to study and explore its mysteries.2. How did the universe begin?The most widely accepted theory of the universe'sorigin is the Big Bang theory. According to this theory, the universe began as a singularity a point of infinite density and temperature around 13.8 billion years ago. This singularity then rapidly expanded in an event known as the Big Bang, creating all matter and energy in the universe.3. What is dark matter?Dark matter is a type of matter that does not emit, absorb, or reflect light, making it invisible to telescopes and other instruments that detect electromagnetic radiation. However, its presence can be inferred from itsgravitational effects on visible matter. Scientistsestimate that dark matter makes up around 85% of the total matter in the universe, but its exact nature is still unknown.4. What is a black hole?A black hole is a region of space where gravity is so strong that nothing, not even light, can escape its pull.It is formed when a massive star collapses in on itself, creating a singularity with infinite density and no volume. Black holes are invisible, but their presence can beinferred from their effects on nearby matter, such as stars orbiting around a point in space.5. Is there life beyond Earth?Scientists have not yet discovered any definitive evidence of life beyond Earth, but the possibility exists. There are billions of planets in the Milky Way galaxy alone, and many of them are located in the habitable zone around their star the region where conditions are favorable for liquid water and potentially life. However, the search for extraterrestrial life is still ongoing and requires further exploration and research.。