高中英语 Unit3 Life in the Future教案 新人教版必修5

高中英语 Unit3 Life in the Future教案 新人教版必修5,标签：高二英语教学设计案例,http://www.5ijcw.com
The company will organize some perfect performances. We will offer permanent band to play for dancing every night. Also we will invite different stage companies to come to our entertainment center to give wonderful plays.
We hope that these programmes and facilities will help you relax yourselves. We hope that you will come and try our entertainment center for yourselves.

附 件
文化背景知识
TIME TRAVEL
Shaping the future
The idea of traveling forward into the future or back into the past has always fascinated science fiction writers. The “grandfather paradox” is the argument that many people use to suggest that time travel is impossible. What if you went back in time and prevented your grandfather from meeting your grandmother so that your mother was never born? Then you would never have been born ... and so on.
Until very recently such arguments led most scientists to believe that time travel could never exist outside science fiction. But amazingly, some interpretations of the weirdness of the quantum world now suggest that time travel is possible — at least in theory.

Gravity and black holes
Einstein’s theory of relativity brought space and time together in a single, four-dimensional arrange-ment that he called space-time. We know that we can travel forwards, backwards and sideways in space, so why not forwards and backwards in time?
Four dimensions are difficult to imagine, so physicists usually suggest you think of space-time as a rubber sheet stretched out flat. If there are no large masses around, the sheet stays flat, and so any object placed on it will move around in straight lines. But a large mass, such as the sun, makes a dip in the sheet because it actually warps space-time. Now any other object with smaller mass, like our earth, moving about in space-time rolls into the dip as it comes past the sun. It appears “attracted” to the large mass. This effect of warping space-time is what gives rise to gravity.

www.5ijcw.com The Universe is full of heavy objects exerting gravitational effects and the net result is that space-time is not flat at all but curved. Everything, including light, has to follow curved paths in space-time. We know Einstein was right about this because astronomers can sometimes see distant stars that ought to be masked by nearer objects such as the sun. Instead of traveling in straight lines and hence being blocked, the light from the stars bends round the obstruction.
When a star reaches the end of its life it mat collapse inwards under the influence of its own gravity to such an extent that all its matter becomes concentrated into an extremely dense object, a fraction of its original size. This is a black hole. Black holes have such a huge gravitational pull that nothing can escape from them, not even light. We cannot see them but we have good evidence that they are being pulled about by a nearby invisible object with enormous mass.
What does a black hole do to space-time? Relativity predicts that at the center of a black hole is an infinitely dense point, called a singularity, within which all the normal laws of physics no longer apply. Time, space, matter and energy no longer have any well-defined meaning. Einstein’s equations show that such a singularity doesn’t just make a dip in the imaginary rubber sheet of space- time, it makes a tunnel that goes right through and momentarily opens out on the other side. Where is “the other side”? It could be somewhere else in space-time, either in the future or in the past, or it could even be in another Universe! Supposedly it was Derwood’s Time lords who first harnessed the power of a black hole to begin their experiments in time travel. If you could take a space trip through such a tunnel, or wormhole, you would have discovered the secret of time travel. This is of course impossible with today’s technology. But in the future, who knows?

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