Passage 6
Scientists Simulated Millions of Universes on a Supercomputer to Study Galaxy Formation
Through the looking glass: To better understand how galaxies actually form, we need to be able to observe their formation and growth over billions of years. In lieu of a time machine, scientists from the University of Arizona are using a supercomputer to simulate millions of universes and galaxies.
Scientists have studied the formation of galaxies using cutting-edge technology for decades, yet even still, we’ve barely scratched the surface of understanding exactly how these massive bodies grow, evolve and behave.
It’s an issue of scale and time, really: they’re so enormously large and have been around for so long that our observations only provide a snapshot in time. Peter Behroozi, an assistant professor at the UA Steward Observatory, said simulating a single galaxy requires 10 to the 48 th computing operations. “All computers on Earth combined could not to do this in a hundred years. So to just simulate a single galaxy, let alone 12 million, we had to do this differently,” he said.
As much, each simulated universe was coded to obey different physical theories on how galaxies should form. Over a three-week period, the “Ocelote” supercomputer at the UA High Performance Computing Cluster crunched numbers, processing data on more than eight million simulated universes and 12 million galaxies spanning from about 400 million years after the Big Bang to present day.
The results have helped scientists understand why galaxies cease to form new stars even when they have plenty of hydrogen gas to do so.
“As we go back earlier and earlier in the universe, we would expect the dark matter to be denser, and therefore the gas to be getting hotter and hotter. This is bad for star formation, so we had thought that many galaxies in the early universe should have stopped forming stars a long time ago,” Behroozi said. “But we found the opposite: galaxies of a given size were more likely to form stars at a higher rate.”
48. Scientists better understand how galaxies actually form by ( ).
A. a supercomputer
B. a time machine
C. cutting-edge aerospace technology
D. space stations
【答案】A。根据文章标题以及第一段 Through the looking glass: To better understand how galaxies actually form…In lieu of a time machine, scientists from the University of Arizona are using a supercomputer to simulate millions of universes and galaxies.可知科学家们通过超级计算机代替时光机去观察宇宙银河。选项 A：超级计算机;选项 B：时光机;选项 C：先进的航空技术;选项 D：太空站。故正确答案是选项 A。
49. Which of the following is not true according to the first three paragraphs? ( )
A. Observations supported by cutting-edge technology can offer long-term record for the study of galaxies.
B. Scientists’ research on the formation and evolution of the universe only stays on the surface.
C. Scale and time add the difficulty to study galaxies.
D. Simulating a single galaxy requires all computers on Earth to work more than hundred years.
【答案】A。根据第 2 段 using cutting-edge technology for decades, yet even still, we’ve barely scratched the surface of understanding 可知几十年使用先进科技观测，仅仅做到了肤浅的研究，也并未提到是否可以为未来的研究提供长期数据，所以选项 A 表达错误，选项 B表达正确;根据第 3 段 It’s an issue of scale and time, really…可知时间和规模给研究带来了巨大的困难，选项 C 表达正确;根据 All computers on Earth combined could not to do this in a hundred years. So to just simulate a single galaxy…可知所有计算机系统加在一起都无法在百年内计算一个星系，推知选项 D 表达正确。故正确答案是选项 A。
50. Why does the author use several figure in the fourth para? ( )
A. To authentically describe the power of the supercomputer.
B. To highlight the vastness of the universe.
C. To more intuitively describe the difficulty of measuring the universe.
D. To highlight scientists’ great efforts to study galaxy.
【 答 案 】 A 。 定 位 至 第 四 段 Over a three-week period, the “Ocelote” supercomputer…crunched numbers, processing data on more than eight million simulated universes and 12 million galaxies spanning from about 400 million years after the Big Bang to present day.可知描述的是超级计算机在三周时间内处理了超过八百万被编码星球和一千两百万星系，从大爆炸时代之后大约四亿年的数据，从中可以看出作者用这些数据就是为了展现超级计算机的能力。选项 A：用事实描述超级计算机的能力;选项 B：强调宇宙的巨大;选项 C：更直观描述宇宙测量的困难;选项 D：强调科学家们在对银河星系研究的努力。结合语境可知选项中只有 A 项更符合段意，故正确答案是选项 A。
51. Study showed that galaxies cease to form new stars ( ).
A. because of the hotter gas.
B. because they gave no given size.
C. because of the denser dark matter.
D. because of the lack of other materials.
【答案】A。定位至末段可知高浓度黑物质带来的气体温度变高，使得新星体很难形成。所以科学家推测许多星系已经很早之前不再形成新星体。所以研究表明星系不再产生新星体是由于高浓度黑物质带来的高温气体。选项中只有 A 项：高温气体，与题干构成因果关系。故正确答案是选项 A。
52. What conclusion did scientists get which are contrary to their expectation? ( )
A. The Correlation between Galaxy Growth and Dark Matter.
B. Certain galaxies might form stars at a high rate.
C. There were 12 million galaxies spanning from about 400 million years after the Big Bang to present day.
D. The reason why galaxies cease form new stars.
【答案】B。根据文章末段最后一句 But we found the opposite: galaxies of a given size were more likely to form stars at a higher rate.可知实验又发现事实反而是相反的，一些已知星系反而更容易以更快的速度产生新星体，而这是与他们初期设想是相违背的。选项 A：星系增长速度和黑物质之间的关系;选项 B：有一些星系会以更快速度产生新星体;选项 C：大爆炸时代之后至今四亿年有超过一千两百万星系;选项 D：星系不再产生新星体的原因。结合文段，可知选项中只有 B 项表达符合文意。故正确答案是选项 B。
