哈尔岑获诺贝尔物理学奖：他把南极的冰变成了捕捉幽灵粒子的望远镜

Every second, huge numbers of neutrinos pass through your body, and you feel nothing.

In the time you hear this sentence, more than a billion neutrinos have passed through your hand.

Neutrinos barely react with anything, so scientists gave them a nickname: ghost particles.

This year's Nobel Prize in physics goes to a man who found a way to 'catch' ghosts.

On October 6th, 82-year-old Belgian physicist Francis Halzen won, for his decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos from the cosmos.

This year's physics prize went to him alone, which has been very rare in the last thirty-odd years.

The biggest problem in seeing neutrinos is that they're too hard to catch.

To improve the odds, you need an enormous detector.

In 1988, Halzen proposed a bold idea: just use the Antarctic ice.

Antarctic ice is thick, pure and almost transparent, perfect to use as a giant detector.

So near America's Amundsen-Scott station at the South Pole, scientists drilled eighty-six deep holes into the ice and lowered 5,160 light sensors into them.

These sensors are spread about two kilometers under the ice, taking up a cubic kilometer of ice in all.

The whole project was finished in 2010 at a cost of 279 million dollars, with more than 450 scientists from fourteen countries.

So how does it 'see' neutrinos?

The vast majority of neutrinos pass straight through the ice.

But occasionally, a neutrino hits an atom in the ice and produces other particles, which move very fast through the ice and give off a faint blue light.

The sensors record where and when this light appears, and scientists can work back to which direction in the sky the neutrino came from.

In 2013, two years after IceCube began full operation, the team announced it had found twenty-eight high-energy neutrinos from beyond the solar system.

It was the first time humans had confirmed seeing neutrinos from the distant universe.

Later, IceCube traced a neutrino to a distant galaxy, and even drew a 'neutrino map' of the Milky Way.

So the Nobel committee said Halzen's work opened up a whole new kind of astronomy.

Before, we looked at the universe using light; now we can also use neutrinos.

The advantage of neutrinos is that they're almost never blocked, so they can carry information from very far away to Earth exactly as it was.

Finally, a word about ourselves.

Last week we introduced Jun Ye, winner of the Wolf Prize, and said he was a leading Nobel contender.

In the end, this year's physics prize went to Halzen.

A bellwether is only a bellwether, but Jun Ye's clock and Halzen's ice are doing the same thing: using the cleverest methods to measure things we normally can't feel at all.

Do you think spending over 200 million dollars to 'see' ghost particles in the Antarctic ice is worth it?