* 本篇文章难度系数7.3，由《小仙英语伴读》人工智能难度分析系统提供评分。
Is it correct that even if we travelled at the speed of light that 94% of the universe's galaxies are still permanently out of our reach since many are 18 billion light years away?* 即使我们以光速行进，94%的宇宙星系仍然永远无法到达，因为许多星系距离我们180亿光年，这说法是正确的吗？* even if 是“即使，纵然”的意思* travelled 原型：travel ['trav-uhl]['trævl] v. 旅行；去某地；传播；快速移动* universe ['yoo-nuh-vurs]['juːnɪvɜːs] n. 宇宙* galaxies 原型：galaxy ['gal-uhk-see]['ɡæləksi] n. 银河；星系* permanently ['pur-muh-nuhnt]['pɜːmənəntli] adv. 永久地* reach [reech][riːtʃ] n. 范围；影响力* billion ['bil-yuh n]['bɪljən] n. 十亿
* light year 光年
Speed of light is not reachable.* 光速是无法达到的。* reachable [reech]['riːtʃəbl] adj. 可达成的；可获得的
Never.* 永远（达不到）
It would require zero rest mass.* 它需要零静止质量。* require [ri-'kwahyuhr][rɪ'kwaɪə] v. 要求；需要* mass [mas][mæs] n. 质量
But lets say we manage to move at 0.99999999999999999999 (20 times of nines) percent of light speed, then we would be at andromeda galaxy in 3.1 hour.* 但假设我们以光速的0.999999999999999（小数点后20个9）倍移动，那么我们将在3.1小时内到达仙女座星系。* manage to do sth．指“（经过努力和克服困难之后）将某事做成”* andromeda [an-'drom-i-duh][天]仙女座；安德洛墨达(希腊神话中人物)
It is purely hypothetical.* 这纯粹是假设。* purely ['pyoo r-lee]['pjʊəli] adv. 纯粹地* hypothetical [hahy-puh-'thet-i-kuhl][ˌhaɪpə'θetɪkl] adj. 假设的；假定的
I don't think the speeds over 0.1c will be economical nor safe.* 我认为速度超过光速的0.1倍既不经济也不安全。* 0.1c中的c指真空光速（约为299,792,458m/s）
* economical [ek-uh-'nom-i-kuhl, ee-kuh-][ˌiːkə'nɒmɪkl] adj. 节俭的；经济的；合算的* safe [seyf][seɪf] adj. 安全的；谨慎的
Back to question - galaxies we see which have about 18billion LY distance(when relativistic effects of universe expansion are compensated) aren't reachable even for light.* 回到问题上来——我们看到的星系距离大约有180亿光年（当宇宙膨胀的相对论效应得到补偿时），即使是光也无法到达。* distance ['dis-tuhns]['dɪstəns] n. 距离；路程* relativistic [rel-uh-tuh-'vis-tik][ˌrelətɪ'vɪstɪk] adj. 相对的；相对论的* expansion [ik-'span-shuhn][ɪk'spænʃn] n. 膨胀；扩展* compensated 原型：compensate ['kom-puhn-seyt]['kɒmpenseɪt] v. 补偿；赔偿* LY 即 light year，光年，是距离的单位
Those parts are visible only because the light was sent before the speed of distancing was still lower than speed of light.* 这些部分（能看到的星系）之所以能被我们看到，是因为这些光是在它们拉开距离的速度仍然低于光速之前发出的。* visible ['viz-uh-buhl]['vɪzəbl] adj. 看得见的；可见的* sent 原型：send [send][send] vt. 发送* distancing 原型：distance ['dis-tuhns]['dɪstəns] vt. 拉开与 ... 的距离
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