日韩午夜精品视频,欧美私密网站,国产一区二区三区四区,国产主播一区二区三区四区

Is the universe eternal, or did it have a beginning?

Giving his conclusion on the matter, world-renowned theoretical physicist Stephen Hawking made a 45-minute multimedia presentation at the Great Hall of the People in Beijing yesterday on the occasion of the International Conference on String Theory 2006.

String theory traces the development of theories on cosmic origin.

Through his electronic speech synthesizer, Hawking described how the general theory of relativity and the discovery of the expansion of the universe provoked conceptual changes, which meant that the idea of an ever-existing, ever-lasting universe was no longer tenable.

The 64-year-old scientist and author of the global best-seller A Brief History of Time uses a wheelchair and communicates with the help of a computer because he suffers from the neurological disorder, amyotrophic lateral sclerosis or ALS.

One of the best-known theoretical physicists of his generation, Hawking has done groundbreaking research on black holes and the origins of the universe, proposing that space and time have no beginning and no end.

The image Hawking drew of this process was that of bubbles appearing and bursting, corresponding to mini universes that expand and collapse. Only those that grew to a certain size would be safe from collapse and would continue to expand at an ever increasing rate.

According to the theorem he and Professor Roger Penrose jointly developed in 1970, general relativity predicated that the universe and time itself would begin with the big bang and that time would come to an end in black holes.

"One can get rid of the problem of time having a beginning in a similar way in which we got rid of the edge of the world," Hawking said.

Likening the beginning of the universe to the South Pole, with degrees of latitude playing the role of time, Hawking explained that the universe would start as a point at the South Pole.

"As one moves north, the circles of constant latitude, representing the size of the universe, would expand. To ask what happened before the beginning of the universe would become a meaningless question because there is nothing south of the South Pole," Hawking said.

In this view, the beginning of the universe would be governed by the laws of science: the creation of the universe would be down to spontaneous quantum creation.

"Cosmology is a very exciting and active subject. We are getting close to answering the age-old questions, 'Why are we here?' and 'Where did we come from?'"

(Xinhua News Agency June 20, 2006)