国际科技信息

2011-11-14

中国科技信息 2011年20期

关键词：汽车

国际科技信息

World Population To Pass 7 Billion On October 31

The world's population is projected to pass 7 billion on October 31 as it heads toward 10 billion or more by the end of the century, a new U.N. report said on Tuesday.

The report also predicted that the global population would be higher by midcentury than its last edition forecast two years ago, reaching 9.31 billion instead of 9.15 billion. It attributed this to fewer deaths as well as more births than it had anticipated.

The October date for reaching the 7 billion mark is based on calculations from current trends and Hania Zlotnik, head of the U.N. economic department's population division, said it should be taken "with a grain of salt."

Nevertheless, the United Nations Population Fund (UNFPA) announced it would start a seven-day countdown on October 24 that would include a series of events. The world reached 6 billion people in 1998 and was 6.89 on July 1.

The report, "2010 Revision of World Population Prospects," projected there would be 10.1 billion people on the planet by 2100, the first time it has looked that far ahead. But it said that if global fertility was just half a child more per woman than it expected, that figure could be almost 16 billion.

U.N. officials said their figures were based on the assumption that fertility would taper off during the century.

But Zlotnik told a news conference, "Stabilization of the population doesn't seem to us as very probable at this moment."

Nations face a delicate balance between high fertility and booming populations, which strain food and other resources, and low fertility, which leads to aging populations and stress on social services, as some European states are already finding.

"All countries are going to age if their populations are not to explode even more than they are exploding now," Zlotnik said.

Another U.N. official,

地球人口突破70亿大关

Gerhard Heilig, told the news conference that China's population, currently about 1.34 billion, would drop back below 1 billion by 2100. Russia's population would fall from 143 million now to 126 million by 2050 and 111 million in 2100, he said.

But UNFPA chief Babatunde Osotimehin said the latest global figures "underscore the urgent need to provide safe and effective family planning to the 215 million women who lack it," a point echoed by pro-birth control advocacy groups.

Suzanne Ehlers, president of Washington-based Population Action International, called the new projections "a wakeup call for governments to fulfill the global demand for contraception."

法国国家人口研究所的最新研究报告显示，地球人口自1800年以来已经增长7倍，现在已经突破70亿大关。估计到下世纪初，地球人口能够稳定在90亿到100亿左右。

该研究报告指出，1999年地球人口超过60亿，而2011年这个数字已经超过70亿，在短短十多年内地球人口增加了10亿。虽然目前地球人口增长幅度逐渐趋缓，但趋缓的程度十分有限，据估计，2025年时地球人口将达到80亿。

联合国预测本世纪末地球人口即可达到90亿到100亿，而法国国家人口研究所的报告稍显乐观，认为直到2100年地球人口才会达到90亿至100亿。

人口之所以快速增长，主要是因为医疗卫生条件的改善，特别是婴儿死亡率的大大降低。19世纪初时人类的平均寿命仅为25岁，而今天人类平均寿命已达到68岁。从各大洲的情况看，亚洲人口占世界人口的比例超过60%，而非洲目前虽然只有10亿人口，但是由于这一地区的生育率较高，到本世纪末，非洲将经历一个人口急速增长阶段，预计到2100年，仅非洲大陆人口将达到36亿。

Telescope to spot aliens: World's largest eye on the sky to join quest for signs of ET

Housed in a dome almost the size of Big Ben and containing a mirror nearly half the length of a football pitch, it wasn’t exactly rocket science for astronomers to find a name for this telescope.

And, sure enough, they came up with the European Extremely Large Telescope —just about the only routine thing about the world’s largest and most powerful‘eye on the sky’.

Astronomers reckon it may finally shed light on whether there really is life somewhere out there by helping them find Earth-like rocky worlds that are home to other beings.

And British scientists might be among the first to find out — as their work is crucial to the project.

Key instruments for the telescope will be developed thanks to £3.5million funding from the Science and Technology Facilities Council.

The device in the Atacama Desert, Chile, will be built in a dome that covers an area the size of a stadium.

It has a sensitivity to visible and infrared light tens of times greater than any previous telescope, and is designed to help astronomers peer back to the first galaxies 14billion years ago.

This could unlock secrets of dark matter and dark energy — little-understood forces in space — to help explain how the universe evolved, according to the plans.

The British instruments are being developed by the universities of Durham and Oxford, with the UK Astronomy Technology Centre and Rutherford Appleton Laboratory.

They will include spectrometers to analyse the light received from space, as well as gadgets to help remove blurring distortions caused by the Earth’s atmosphere, a process known as adaptive optics.

This will produce pictures 15 times sharper than those taken by the Hubble space telescope, which has been in orbit since 1990.

Professor Isobel Hook, E-ELT project scientist at the University of Oxford, said: ‘This new financial commitment from the STFC means that UK astronomers will have access to the earliest scientific results from this revolutionary telescope — an exciting prospect.’

It is believed the telescope will bring hundreds of millions of pounds of benefits to British companies involved in building it.

They include a consortium based at the OpTIC Technium in North Wales, which is developing prototypes for the huge segments needed to make the 43-yard mirror.

Engineers will have to blast the top off Chile’s 9,900ft Cerro Armazones mountain peak to build the telescope if final approval is given by the European Southern Observatory’s 15 international partners in December. It is hoped the observatory will be operating by 2020.

The E-ELT will be the latest tool to join observatories operated in Chile by Europe.

The Atacama is a favoured location because the dryness and clarity of the air provide exceptional observing conditions.

Established telescopes include the Atacama Large Millimeter Array, a set of dishes that forms the highest observatory in the world at 16,000ft.