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为什么物理学不能完全解释宇宙的膨胀 – 译学馆
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为什么物理学不能完全解释宇宙的膨胀

Why Physics Can't Totally Explain the Universe's Expansion | SciShow News

Since the moment it began, the universe has been expanding.
宇宙自诞生以来就一直在膨胀
It took humanity a while to figure that out,
人类花了一段时间来认清这一点
but over the last century, astronomers have gotten pretty good at calculating
上个世纪的天文学家就已善于计算
how fast it’s happening and how
宇宙膨胀的速度和
that speed has changed over the past 14 billion years.
过去140亿年膨胀速度的变化
Right now, there are two main methods for measuring this:
目前测量膨胀速度有两种方法:
You can either observe astrophysical objects, like stars and supernovas,
一种是观测天体对象 例如恒星和超新星
or you can use the laws of physics to extrapolate
另一种是运用物理学定律
from data about the very old universe.
从非常久远的宇宙数据中进行推算
Both methods are great, but they also don’t quite agree.
两种方法都很好 但测量结果不怎么一致
And according to a new set of measurements to be published in The Astrophysical Journal,
依据一套将发表于《天文物理期刊》的新测量结果
that might not be a mistake.
这种不一致并不是错误
The two numbers might actually be different.
两种方法测得的数字可能真的不同
And to explain that
要解释这种现象
we’d have to rethink our understanding of physics.
就要重新思考我们对物理学的理解
Right now, when we say that the universe is expanding,
现在我们说宇宙膨胀
we mostly mean that the void between the
大部分指的是各种星系和
galaxies and other large objects is growing.
其他大型天体之间的距离在增大
It’s a technical thing, but strictly speaking,
这是专业的事 但严格来说
the universe isn’t expanding everywhere.
宇宙并不是每个地方都在膨胀
Regardless, one of the tried and true methods of measuring this expansion requires calculating
不管怎样 一个行之有效测量宇宙膨胀的方法
the distances to stars called Cepheid variables.
要计算天体到造父变星的距离
A Cepheid is a star whose brightness changes over very regular periods of time.
造父变星是一种亮度随时间呈周期性变化的变星
And the length of that period is directly related to how bright the star is.
光变周期与变星的亮度有直接的关系
So as long as scientists can measure how fast these objects change,
科学家只要测出这些天体的变化速度
they can figure out how bright they are up-close.
他们就能搞清楚造父变星近距离内的亮度
Then they can compare that number to
然后他们可以通过比较这些数据和
how bright the stars look from Earth
从地球肉眼观测到的星体亮度
to determine their distance.
得出星体的距离
Using sets of Cepheids at different distances,
采用不同距离的造父变星
along with data about other kinds of objects,
结合其他类型的天体数据
you can then figure out how fast the universe is expanding.
你就能计算出宇宙膨胀的速度
There are a few other ways to measure this,
另外还有些其它的测量方法
but Cepheid variables were especially important for this new study.
但造父变星在这项新的研究中非常重要
In it, researchers used the Hubble Space Telescope
这项研究中 研究员用哈勃空间望远镜
to look at 70 Cepheids in a nearby dwarf galaxy:
观测了附近有70颗造父变星的矮星系:
the Large Magellanic Cloud.
大麦哲伦星系
It’s only about 162,000 light-years away,
距离地球仅有162000光年
which is super duper close on a universal scale.
从宇宙的量度上来看已经非常非常近了
Then, to make sure their brightness measurements were as accurate as possible,
为了确保亮度测量结果尽可能准确
the scientists combined their data with results from a few other sources,
科学家们结合了其他项目测得的数据
including an international collaboration called the Araucaria Project.
比如一个叫南洋杉项目的国际合作
This group calculated the distance to the Cloud a different way:
这个团队采用另一种方法计算出星云的距离:
by watching the light of binary star systems
通过观测双子星在围绕
change as the stars moved around one another.
对方转动的光度变化测出结果
That movement allowed them to figure out stuff
科学家们可以根据双子星互转
like the stars’ masses and how big they are.
运动计算出星体的质量和大小
And by combining that with data about how fast those changes happened
将星体质量大小和光度变化的速度
and what kind of light the stars emitted,
以及星体发光类型的数据结合
the scientists could ultimately work out how far away they are.
最后科学家就能算出星体的距离
After looking at all this data,
看过这些数据后
the authors of this new paper reported that
这项新研究的论文作者表示
the universe is expanding at… drumroll please… about 74.03 kilometers per second per Megaparsec.
宇宙以每百万秒差距每秒74.03千米的速度在膨胀
In other words, an object 1 million parsecs away
也就是说 有一百万秒差距远
or roughly 3.3 million light-years
或者说大约330万光年远的天体
is moving away from us at about 74 kilometers per second.
正以每秒74千米的速度远离我们
An object 2 million parsecs away is
一个两百万秒差距远的天体
moving away at about 148 kilometers per second,
以每秒148千米的速度远离地球
and so on and so forth.
以此类推
74.03 kilometers per second per Megaparsec
每百万秒差距每秒74.03千米的速度
that’s amazing!
非常不可思议!
That’s amazingly specific!
不可思议地精确!
Now despite all the work that went into it,
先不管投入的工作量
that estimate isn’t actually groundbreaking at first glance,
实际上 这种预测一眼看过去没有突破性
since it’s basically in line with previous measurements.
因为它和以前的测量基本是一致的
But the key is that this number has far less uncertainty.
但关键是这个数字的不确定性少了很多
And that’s causing a problem,
这引发了一个问题
because that estimate conflicts with other confident measurements about the universe’s expansion.
因为这个预测和其他测量宇宙膨胀的可靠结果冲突
Like I mentioned earlier,
如我之前所述
Cepheid variables aren’t the only way we can figure out how the universe is growing.
造父变星并不是弄清宇宙如何膨胀的唯一方法
Another method is by studying the Cosmic Microwave Background, or CMB.
另一种方法是研究宇宙微波背景 即CMB
This is the oldest light in the universe that humanity will ever see.
这是人类能观测到的宇宙最久远的光
It dates back to when the cosmos was only about 380,000 years old,
可以追溯到宇宙只有38万岁时
and studying it is the main objective of the European Space Agency’s Planck telescope.
研究CMB是欧洲航天局普朗克望远镜的主要目的
By studying temperature fluctuations in this light,
通过研究这个光的温度波动
scientists have been able to determine how fast
科学家已经能确定
the universe was expanding those 13-ish billion years ago.
130亿年前的宇宙膨胀速度
Then, they’ve been able to use that to extrapolate and figure out what the expansion rate should be today.
然后用这个数据推算和弄清现在的宇宙膨胀速度
Those extrapolations are all based on, like,
这些推算都建立在
really well-tested laws of physics, so you
经过良好验证的物理学定律上
would think these results would match up
所以你会认为这些结果会和
pretty well with what we’ve observed with instruments like Hubble.
使用像哈勃这样的工具观测的结果完美吻合
Except, that they don’t.
但是并不吻合
The Planck expansion rate is noticeably lower
普朗克膨胀率明显
than what we’ve gotten using sources like Cepheids.
比用造父变星的数据计算的速度低
It’s only 67.4 kilometers per second per Megaparsec.
只有每百万秒差距每秒67.4千米
This discrepancy isn’t new,
这种不一致并不是新发现
but there was always a chance that it was a fluke.
但也可能是个意外
Like last year, scientists estimated that
比如去年 科学家就估计
there was a 1 in 3000 chance something had just gotten messed up.
有三千分之一的概率会出错
But now, with this updated Hubble data,
但是现在 随着哈勃数据的更新
the chance is 1 in 100,000.
概率降到了100000分之一
Which means that while it’s not impossible
也就是说 尽管不是不可能
it is pretty unlikely these numbers are wrong.
但是这些数字是出错的可能性是很低的
In other words,
换而言之
scientists now have to explain
科学家必须要解释
why the observed expansion rate is almost
为什么观测的膨胀速度
10% faster than what physics predicts it should be.
大约比物理学预测的快了10%
One current hypothesis is that
目前的一个假设是
there was yet another incident where mysterious dark energy
宇宙中还有其他的事件 那就是神秘的暗能量
caused an increase in the universe’s expansion rate.
导致了宇宙膨胀率的增长
Scientists don’t really know what dark energy is,
其实科学家并不确切知道什么是暗能量
but they believe something like this has already happened twice
但他们认为类似于这样的事发生过两次
once for a brief moment after the Big Bang,
第一次发生在宇宙大爆炸后的短暂时间
and again starting few billion years ago.
第二次发生在几十亿年前
So maybe there was another incident like that between those two points.
所以这两个时间点之间可能发生了其他类似事件
Another idea is that dark matter interacts differently
另一种观点是暗物质和普通物质
with regular matter and light than we think.
以及光相互作用时和我们所想的有所不同
Dark matter is stuff that doesn’t interact with light or charged particles,
暗物质是不和光或带电粒子反应的
so it’s basically invisible.
所以基本上是看不到的
We only know it’s there
我们只知道暗物质存在
because of the gravitational effect it has on regular matter and light.
是因为它对普通物质和光有引力影响
But we could be wrong about how strong its influence is on that stuff.
但我们可能对暗物质对光的影响有多大有误解
If its influence is stronger,
如果它的影响更大
it could have countered the universe’s expansion early-on.
那就会和早期的宇宙膨胀相抵消
Then again,
那么
both of these ideas could also be wrong
这两种观点可能都不对
maybe there’s some exotic particle we haven’t discovered yet that’s responsible for all of this.
可能有一些我们尚未发现的奇特粒子导致了这一切
Ultimately, this is yet another example of answers
最终 正如经常发生的那样
in science just spurring more questions.
这一科学问题的答案 又催生了更多问题
But there are ways scientists could explore this further,
但科学家们还有进一步探索的方法
including using gravitational waves produced in black hole and neutron star mergers.
例如利用黑洞和中子星合并产生的引力波
Those are ripples in spacetime that
引力波是时空弯曲中的涟漪
squish you know, like everything, like….
穿越宇宙时它们只占一小部分
Everything that exists in space-time including earth
但是会挤压一切
just a teeny bit as they travel through the cosmos.
它们会挤压时空中的一切包括地球
Since they don’t rely on light,
由于它们不依靠光
measuring those waves would give us a totally new set
测量引力波就能得出一组新的
of data to study the expansion rate
研究膨胀速率的数据
but right now, this field of astronomy is really young,
但现在这个天文学领域还很不成熟
so we can’t draw any conclusions.
因此我们无法得出任何结论
In our day to day lives,
在我们日复一日的生活中
narrowing down these big-picture cosmological factors doesn’t
减少这样宏大的宇宙学因素
always feel that important.
并不是那么重要
Like, knowing how fast the universe is
知道宇宙膨胀的速度
expanding isn’t going to help you write a paper or
不能帮你完成一篇论文
get through another day at work.
也不能帮你完成一天的工作
But this field is all about discovering and understanding the fundamental rules for how everything works
但这个领域是探索了解万物运转的基础法则
from Cepheids way out in space to the gravity that keeps you here on the planet.
从宇宙的造父变星到地球的地心引力
And in a lot of ways,
在很多方面
being curious and exploring big questions
保持好奇心 探索大问题
is a lot of what makes us human.
是人类得以与众不同的很大原因
Thanks for watching this episode of SciShow Space News,
感谢您观看本期的太空科学秀
and thanks to all our patrons
同时感谢所有在Patreon上
on Patreon for helping us make it!
帮助我们的赞助者!
We wanted to give a special shout-out to this week’s President of Space,
我们想对本周的空间长致以特别感谢
SR Foxley.
SR Foxley
Thanks for supporting us!
感谢对我们的支持
If you want to become our next President of Space
如果你想成为我们的下任空间长
or just help us keep making more episodes of SciShow,
或者是想帮我们制作更多期节目
you can head over to patreon.com/scishow.
请登陆以下网站patreon.com/scishow

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