英语听力：自然百科 穿越银河系的旅行 Through Milky Way—25
时间：2014-05-27 07:53:18
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（单词翻译）
What happens is that, first the dark matter forms the structure, the ordinary matter then follows the dark matter. The ordinary matter is hydrogen and helium at this stage. And the hydrogen and helium fall/ to the center of the dark matter halos that are forming and that's when it becomes the galaxies1.
If these ideas are right, then the link between these minute
ripples2 in the early universe and the vast cosmic web that now fills space is dark matter.
But of course, dark matter is invisible, so there is no way to see it creating the cosmic web. But it is possible to simulate the process using one of the world's most powerful supercomputers.
Here we are at NASA AMES, the research center where we have the Pleiades supercomputer. Each one of these cabinets contains 512 processors, let me show you. So that's half a terabyte in each one of these cabinets. There's a hundred ton of these cabinets to make up the entire Pleiades supercomputer. So this is a really big supercomputer, this is NASA's biggest.
The challenge is to develop a virtual universe from its early beginnings to the present day to see what role dark matter might have played in shaping the
cosmos3. If you try to do this using a home computer, it would take almost 700 years.
If we're doing our job right, we can put the pictures into a video if you like that shows the whole structure of the universe.
And this is the end-result. It's called Bolshoi, an amazing
visualization4 of what the structure of dark matter might look like in the universe today.
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