詹姆斯·韦伯望远镜是如何工作的?

在我们录制这一集的时候，价值100亿美元的詹姆斯·韦伯望远镜正朝着它的最终目的地前进。我们询问了天体物理学家贝基·斯梅瑟斯特，我们希望用这台望远镜看到什么，以及它是否能告诉我们更多关于宇宙中潜在的其他生命形式……

贝基:100%。这是詹姆斯·韦伯太空望远镜(我们称之为JWST)的主要科学目标之一。所以詹姆斯·韦伯被设计用来观察红外光。这是詹姆斯·韦伯的关键所在，也是为什么它需要如此遥远的地方，需要一个巨大的网球场大小的遮阳板来保护它免受来自太阳的红外线的伤害。但它能看到的是哈勃太空望远镜看不见的东西因为它看的是可见光。问题是，从离我们最远的恒星和星系发出的光，从宇宙开始发出的光，现在还在向我们传播，因为宇宙的膨胀而发生了红移。所以空间在膨胀，它本质上把光波拖出去，沿着更红的波长延伸。但它被拉伸得太长，以至于当它作为可见光发射时，它现在是红外光。所以哈勃根本没有机会看到它。它甚至不能把它捡起来。 It's not that it's just faint, it can't detect it. So this is what James Webb has been designed to do, is to see the light from the first stars and galaxies that there ever was in the universe, essentially to detect the oldest light that is. And so that's what I'm really excited for. It also might answer sort of like a chicken or an egg question - whether the first stars form, make a black hole, and then that become the first super massive black hole that happened to then fall and sink to the centre of a galaxy, because it was the heaviest thing. Or did a super massive black hole collapse from the first gas in the universe and then a galaxy of stars form around it. But then the other thing that the JWST can do because it works in the infrared, is look at the fingerprints of different molecules in terms of the light they absorb or emit. A lot of the key ones for life are in the infrared; water specifically leaves a fingerprint on infrared light so that we know that it's there. So the plan is, for what we call exoplanets, planets that orbit other stars in our galaxy, when they pass in front of the star that they orbit, we can take the tiny amount of starlight that happened to pass through the skinny bit of atmosphere around them, isolate it and work out what molecules are present in that atmosphere and whether water is present there and other indicators of life biomarkers, biosignatures as we call them. We could be in a position in five years time, where we find the most habitable place for life that we've ever seen beyond earth.

朱莉娅:那太酷了!