s*****t
发帖数: 1994 | 1 BEIJING -- China is about to join the hunt for dark energy. At a cosmology
workshop held here on 20 March, scientists unveiled Tianlai, or "Sound of
Heaven," a project to listen to radio emissions from deep space that may
reveal the nature of dark energy.
Dark energy is the mysterious force driving the accelerating expansion of
the universe. Although not directly observable, the phenomenon "can be
studied by observing the expansion rate of the universe at different epochs,
" says Tianlai project leader Chen Xuelei, a cosmologist at National
Astronomical Observatories of China here. The principle idea is to use a
radio telescope to map neutral hydrogen, which emits or absorbs radio waves
with a wavelength of 21 centimeters. They will be able to peer back to
earlier ages in the universe by looking for redshifted radio waves. The
distribution of hydrogen offers a way to more precisely measure the universe
's expansion rate.
Detecting the cosmic 21-centimeter signal is notoriously hard, as it is
swamped by radiation from our own Milky Way galaxy. The radiation must be
measured to a precision of one in 100-thousandths to see the signal. "Many
colleagues have doubts about whether it will ever work," says Chen. In
collaboration with Canadian, French, and U.S. researchers, Chen's group has
just launched a pilot project to build a prototype cylinder radio telescope.
After a few years of experiments, the team should know whether the new
instrument can detect dark energy. If successful, the project would be
expanded to make a three-dimensional map of hydrogen in the universe. | s*****t
发帖数: 1994 | 2 本篇的主人公就是曾经活跃在本版的网友哟。
epochs,
waves
【在 s*****t 的大作中提到】
: BEIJING -- China is about to join the hunt for dark energy. At a cosmology
: workshop held here on 20 March, scientists unveiled Tianlai, or "Sound of
: Heaven," a project to listen to radio emissions from deep space that may
: reveal the nature of dark energy.
: Dark energy is the mysterious force driving the accelerating expansion of
: the universe. Although not directly observable, the phenomenon "can be
: studied by observing the expansion rate of the universe at different epochs,
: " says Tianlai project leader Chen Xuelei, a cosmologist at National
: Astronomical Observatories of China here. The principle idea is to use a
: radio telescope to map neutral hydrogen, which emits or absorbs radio waves
| s*******n
发帖数: 1474 | 3 恭喜xuelei拉到经费阿
epochs,
waves
【在 s*****t 的大作中提到】
: BEIJING -- China is about to join the hunt for dark energy. At a cosmology
: workshop held here on 20 March, scientists unveiled Tianlai, or "Sound of
: Heaven," a project to listen to radio emissions from deep space that may
: reveal the nature of dark energy.
: Dark energy is the mysterious force driving the accelerating expansion of
: the universe. Although not directly observable, the phenomenon "can be
: studied by observing the expansion rate of the universe at different epochs,
: " says Tianlai project leader Chen Xuelei, a cosmologist at National
: Astronomical Observatories of China here. The principle idea is to use a
: radio telescope to map neutral hydrogen, which emits or absorbs radio waves
| n******e
发帖数: 623 | 4 曾经活跃在本版？是在我来这里（2007）之前吗？ | s*****t
发帖数: 1994 | 5 以前在这里很活跃啊，不过查了下以前的贴子，也就
只有几篇M的了。他哪年回去的，我还真不记得了。
我08年去国台访问的时候，他还见我来着。
【在 n******e 的大作中提到】
: 曾经活跃在本版？是在我来这里（2007）之前吗？
|
|
