Is called protium or light hydrogen.

称为氕或轻氢。

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Some of this energy congealed into particles, which assembled into light atoms like hydrogen and helium.

有些能量凝结成了粒子，这些粒子组合形成了轻原子如氢和氦。

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Instead the nebula glows with light from hydrogen gas being charged by the stars' radiation.

星云的光辉则是来自在恒星强烈辐射作用下带电的氢气。

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One shows the remains of a dying star four thousand light years away which has thrown off a cloud of glowing hydrogen gas.

VOA: special.2009.09.30

By shining laser light onto hydrogen or antihydrogen and observing which wavelengths are absorbed, the energy levels of the two can be compared in detail.

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The barrier to using the devices in vehicles is no one knows how to carry enough hydrogen, a light and flammable gas that is difficult to compress, to be useful.

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Neutrons ejected from a watery surface move much more slowly than those from a rocky one, because the hydrogen nuclei in water are light enough for an exiting neutron to knock around much like one billiard ball hitting another a process that slows the neutron down.

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