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LeisureTime版 - 读 NG 的 Black Holes: Star Eater
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相关话题的讨论汇总
话题: black话题: holes话题: time话题: earth话题: than
进入LeisureTime版参与讨论
1 (共1页)
x*****7
发帖数: 4749
1
三月份的这篇 Black Holes 文章很有趣,连我这种科学白痴都读懂了。。
Copy 其中的一部分关于suck和time的讨论。最后一段说的,不就是我们古人说的,天
上一天,地上万年吗?
这里是原文链接:http://ngm.nationalgeographic.com/2014/03/black-holes/finkel-text
It’s important to clarify a couple of things about black holes. First is
the idea, popularized in science fiction, that black holes are trying to
suck us all in. A black hole has no more vacuuming power than a regular star
; it just possesses extraordinary grip for its size. If our sun suddenly
were to become a black hole—not going to happen, but let’s pretend—it
would retain the same mass, yet its diameter would shrink from 865,000 miles
to less than four miles. Earth would be dark and cold, but our orbit around
the sun wouldn’t change. This black hole sun would exert the same
gravitational tug on our planet as the full-size one. Likewise, if the Earth
were to become a black hole, it would retain its current weight of more
than six sextillion tons (that’s a six followed by 21 zeros) but be shrunk
in size to smaller than an eyeball. The moon, though, wouldn’t move.
So black holes don’t suck. Easy. The next topic, time, is way more of a
mind bender. Time and black holes have a very strange relationship. Actually
time itself—forgetting about black holes for a moment—is an unusual
concept. You probably know the phrase “time is relative.” What this means
is that time doesn’t move at the same speed for everybody. Time, as
Einstein discovered, is affected by gravity. If you place extremely accurate
clocks on every floor of a skyscraper, they will all tick at different
rates. The clocks on the lower floors—closer to the center of the Earth,
where gravity is stronger—will tick a little slower than the ones on the
top floors. You never notice this because the variances are fantastically
small, a spare billionth of a second here and there. Clocks on global
positioning satellites have to be set to tick slightly slower than those on
Earth’s surface. If they didn’t, GPS wouldn’t be accurate.
Black holes, with their incredible gravitational pull, are basically time
machines. Get on a rocket, travel to Sgr A*. Ease extremely close to the
event horizon, but don’t cross it. For every minute you spend there, a
thousand years will pass on Earth. It’s hard to believe, but that’s what
happens. Gravity trumps time.
wh
发帖数: 141625
2
好玩。等calc回帖……

star
miles

【在 x*****7 的大作中提到】
: 三月份的这篇 Black Holes 文章很有趣,连我这种科学白痴都读懂了。。
: Copy 其中的一部分关于suck和time的讨论。最后一段说的,不就是我们古人说的,天
: 上一天,地上万年吗?
: 这里是原文链接:http://ngm.nationalgeographic.com/2014/03/black-holes/finkel-text
: It’s important to clarify a couple of things about black holes. First is
: the idea, popularized in science fiction, that black holes are trying to
: suck us all in. A black hole has no more vacuuming power than a regular star
: ; it just possesses extraordinary grip for its size. If our sun suddenly
: were to become a black hole—not going to happen, but let’s pretend—it
: would retain the same mass, yet its diameter would shrink from 865,000 miles

s**t
发帖数: 17016
3


star
miles

【在 x*****7 的大作中提到】
: 三月份的这篇 Black Holes 文章很有趣,连我这种科学白痴都读懂了。。
: Copy 其中的一部分关于suck和time的讨论。最后一段说的,不就是我们古人说的,天
: 上一天,地上万年吗?
: 这里是原文链接:http://ngm.nationalgeographic.com/2014/03/black-holes/finkel-text
: It’s important to clarify a couple of things about black holes. First is
: the idea, popularized in science fiction, that black holes are trying to
: suck us all in. A black hole has no more vacuuming power than a regular star
: ; it just possesses extraordinary grip for its size. If our sun suddenly
: were to become a black hole—not going to happen, but let’s pretend—it
: would retain the same mass, yet its diameter would shrink from 865,000 miles

c**c
发帖数: 2593
4
呵呵,宇宙是很神奇的,黑洞算是“明”物质里最有趣的东西之一。但宇宙的质量总量
里“明”物质只占4%,其它还有暗物质、暗能量占96%,那更是人类现在还完全不了解
的东西。这样的说法相当不少,靠近黑洞再回来,或在地球上建环球超高速列车,都是
技术上似乎可以做到的时间旅行的方法。还有另一点是,如果你坠入黑洞,越接近视界
,你的时间就越慢,到很靠近视界的地方,时间基本上就停止了。如果你这时还没有被
潮汐力撕碎,如果你还有能接受外部信息的感官,如果你意识还清醒而且能处理所有这
些信息,你将会见证整个宇宙的发展、灭亡。

star
miles

【在 x*****7 的大作中提到】
: 三月份的这篇 Black Holes 文章很有趣,连我这种科学白痴都读懂了。。
: Copy 其中的一部分关于suck和time的讨论。最后一段说的,不就是我们古人说的,天
: 上一天,地上万年吗?
: 这里是原文链接:http://ngm.nationalgeographic.com/2014/03/black-holes/finkel-text
: It’s important to clarify a couple of things about black holes. First is
: the idea, popularized in science fiction, that black holes are trying to
: suck us all in. A black hole has no more vacuuming power than a regular star
: ; it just possesses extraordinary grip for its size. If our sun suddenly
: were to become a black hole—not going to happen, but let’s pretend—it
: would retain the same mass, yet its diameter would shrink from 865,000 miles

x*****7
发帖数: 4749
5
意思是坠入黑洞,就能永生,所以能见证整个宇宙的发展、灭亡?
还有,什么是视界?
这方面我真的懂得太少太少了。。

【在 c**c 的大作中提到】
: 呵呵,宇宙是很神奇的,黑洞算是“明”物质里最有趣的东西之一。但宇宙的质量总量
: 里“明”物质只占4%,其它还有暗物质、暗能量占96%,那更是人类现在还完全不了解
: 的东西。这样的说法相当不少,靠近黑洞再回来,或在地球上建环球超高速列车,都是
: 技术上似乎可以做到的时间旅行的方法。还有另一点是,如果你坠入黑洞,越接近视界
: ,你的时间就越慢,到很靠近视界的地方,时间基本上就停止了。如果你这时还没有被
: 潮汐力撕碎,如果你还有能接受外部信息的感官,如果你意识还清醒而且能处理所有这
: 些信息,你将会见证整个宇宙的发展、灭亡。
:
: star
: miles

c**c
发帖数: 2593
6
视界就是你引的那段文字里的event horizon。进入视界以后,就再也出不来了。在霍
金之前的说法是,黑洞只吸收不吐出东西,那所有的黑洞都只会越变越大,不会变小。
所以有人猜想,宇宙可能有些地方存在白洞,只吐出不吸收东西,来跟黑洞保持平衡,
也许黑洞跟白洞之间的通道,就是超空间旅行的捷径。后来霍金蒸发机制提出来以后,
大家意识到,黑洞不用通过白洞往外吐东西,也会由于霍金蒸发而损失能量。所以一个
黑洞如果很长时间没吸收到新东西,那它也会蒸发殆尽,跟宇宙里其它物质一样,归于
热寂的坟墓。
接近黑洞视界,时间基本停止,但可能也说不上永生吧,要看永生怎么定义,呵呵。

【在 x*****7 的大作中提到】
: 意思是坠入黑洞,就能永生,所以能见证整个宇宙的发展、灭亡?
: 还有,什么是视界?
: 这方面我真的懂得太少太少了。。

L******h
发帖数: 4361
7
谢谢普及科学知识,真是非常有趣!

【在 c**c 的大作中提到】
: 呵呵,宇宙是很神奇的,黑洞算是“明”物质里最有趣的东西之一。但宇宙的质量总量
: 里“明”物质只占4%,其它还有暗物质、暗能量占96%,那更是人类现在还完全不了解
: 的东西。这样的说法相当不少,靠近黑洞再回来,或在地球上建环球超高速列车,都是
: 技术上似乎可以做到的时间旅行的方法。还有另一点是,如果你坠入黑洞,越接近视界
: ,你的时间就越慢,到很靠近视界的地方,时间基本上就停止了。如果你这时还没有被
: 潮汐力撕碎,如果你还有能接受外部信息的感官,如果你意识还清醒而且能处理所有这
: 些信息,你将会见证整个宇宙的发展、灭亡。
:
: star
: miles

L******h
发帖数: 4361
8
对,也不由想起“烂柯山”里“山中方一日,世上已千年”的故事,说一个樵夫进山砍
柴,见俩神仙对弈,看得忘了时间,等下完,发现自己手里的斧子把已经烂掉了。看来
,中国古代就有人推测出时间是相对的,真是先知先觉呀。
不过,既然樵夫没死,斧子也应该不会烂掉,因为他们在同一个时间体系内。;-)

star
miles

【在 x*****7 的大作中提到】
: 三月份的这篇 Black Holes 文章很有趣,连我这种科学白痴都读懂了。。
: Copy 其中的一部分关于suck和time的讨论。最后一段说的,不就是我们古人说的,天
: 上一天,地上万年吗?
: 这里是原文链接:http://ngm.nationalgeographic.com/2014/03/black-holes/finkel-text
: It’s important to clarify a couple of things about black holes. First is
: the idea, popularized in science fiction, that black holes are trying to
: suck us all in. A black hole has no more vacuuming power than a regular star
: ; it just possesses extraordinary grip for its size. If our sun suddenly
: were to become a black hole—not going to happen, but let’s pretend—it
: would retain the same mass, yet its diameter would shrink from 865,000 miles

1 (共1页)
进入LeisureTime版参与讨论
相关主题
宇宙膨胀为什么是越来越快?千老怎么解释?【书与影】《了不起的狐狸爸爸》 (转载)
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白色圣诞节Vincent, Vincent。。。
Discussing The Existence of “repulsion particle” And Its Significance 斥力子存在及其意义a truly true music video
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乐子的总结---雷人的禽兽不如往事看了《Fantastic Beasts and Where to Find Them》
霍金有啥学术成就,出了写本科普读物雷岛的小朋友们
相关话题的讨论汇总
话题: black话题: holes话题: time话题: earth话题: than