String theory - Brian Greene
Summary
TLDR这个视频讲述了德国数学家卡卢扎在1919年提出的大胆假设,即我们的宇宙可能存在超过三个维度的空间。这一理论对20世纪的物理学产生了重大影响,并继续影响着前沿研究。视频还探讨了爱因斯坦如何通过广义相对论解释重力,并尝试寻找一个统一理论来描述自然界的所有力量。卡卢扎和克莱因的理论认为,额外的维度可能是微小且卷曲的,以至于我们无法观察到它们。弦理论的兴起为这一理论提供了新的支持,并且可能在未来几年内通过大型强子对撞机的实验得到验证。
Takeaways
- 🌌 1919年,德国数学家卡卢扎提出了一个大胆的想法,即我们的宇宙可能存在超过三个维度的空间。
- 🔍 爱因斯坦在1907年提出了广义相对论,解释了引力是由空间本身的弯曲造成的。
- 🌐 卡卢扎的额外维度理论在1926年由奥斯卡·克莱因进一步发展,提出了微小的卷曲维度可能存在。
- 🎻 超弦理论是一种尝试统一所有物理定律的新方法,它认为宇宙中的基本构成是由振动的弦组成。
- 📈 弦理论的数学模型只有在存在十个空间维度和一个时间维度的宇宙中才有效。
- 🔬 额外的维度可能对于解释宇宙中约20个基本常数的特定值具有关键作用。
- 🌀 额外维度的复杂几何结构可能影响弦的振动模式,从而决定了宇宙中粒子的性质。
- 💥 在CERN的大型强子对撞机上进行的实验可能在接下来的几年内直接测试额外维度的存在。
- 🔋 如果在高能碰撞后测量到的能量少于碰撞前的能量,这可能是额外维度存在的证据。
- 🌟 这些理论的发展和实验验证是人类对宇宙理解的一次重大飞跃,可能会揭示宇宙更深层次的秘密。
- 🚀 从牛顿的绝对空间到爱因斯坦的弯曲空间,再到超弦理论的多维宇宙,我们对宇宙的认识正不断深化。
Q & A
Theodor Kaluza 提出了一个关于宇宙维度的什么大胆假设?
-Theodor Kaluza 提出了我们的宇宙可能不仅仅包含我们所知的三个维度,而是存在额外的空间维度,这些维度由于某种原因我们目前还看不到。
爱因斯坦是如何描述引力的?
-爱因斯坦描述引力是通过空间本身作为传输介质。他提出,如果没有物质存在,空间是平坦的。但是,当有物质存在时,比如太阳,它会导致空间结构发生弯曲,从而传递引力。
卡尔·施瓦西是如何尝试将电磁力与爱因斯坦的引力理论联系起来的?
-卡尔·施瓦西尝试用类似描述引力的方式,即通过空间的弯曲和扭曲来描述电磁力。他想象如果存在第四个空间维度,那么电磁力就可以在这个额外的维度中以弯曲和扭曲的形式存在。
奥斯卡·克莱因是如何解释额外维度的不可见性的?
-奥斯卡·克莱因提出维度可能有两种类型:大到容易看到的维度和小到卷曲起来的维度。卷曲起来的维度可能非常小,即使它们就在我们周围,我们也看不见它们。
超弦理论是如何复活了关于额外维度的概念的?
-超弦理论是一种尝试回答世界基本构成要素的问题的理论。它提出所有物质和自然力都可以归结为振动的弦。当研究超弦理论的数学时,发现它只在存在十个空间维度和一个时间维度的宇宙中才有效,这复活了卡尔扎和克莱因关于额外维度的概念。
额外维度可能对理解宇宙的基本参数有什么帮助?
-许多科学家相信额外维度可能掌握着解释宇宙基本参数的钥匙。这些参数包括粒子的质量、重力的强度、电磁力的强度等,它们精确地决定了宇宙的结构和存在。
大型强子对撞机(LHC)如何帮助我们测试额外维度的存在?
-大型强子对撞机通过高能粒子碰撞实验,尝试将粒子从我们的维度推向额外维度。如果在碰撞后测量到的能量比碰撞前少,这将是额外维度存在的迹象。
为什么说额外维度的发现对我们理解宇宙至关重要?
-如果额外维度的发现得到证实,这将是对我们理解宇宙的一个重大突破。它不仅会验证超弦理论,还可能解释宇宙的基本参数为何具有当前的值,这些参数决定了宇宙的结构和我们的存在。
卡尔·施瓦西的额外维度理论最初遇到了哪些问题?
-卡尔·施瓦西的额外维度理论最初在细节上并不完全符合实际物理现象,例如,它无法正确解释电子的质量。这些问题导致这一理论在20世纪中叶被搁置。
超弦理论中额外维度的几何结构是什么样的?
-超弦理论中的额外维度具有非常丰富的、交织在一起的几何结构。这些维度以复杂的方式卷曲并相互缠绕,形成了一个微观层面上的复杂景观。
弦理论是如何统一物质粒子和力的粒子的?
-弦理论提出所有物质粒子和力的粒子都是由振动的弦构成的。不同的振动模式产生不同的粒子,这些粒子负责构成我们周围的世界,从而实现了物质和自然力的统一。
未来几年内,科学家们如何可能验证额外维度的存在?
-科学家们计划在未来几年内通过大型强子对撞机(LHC)进行高能粒子碰撞实验,通过观察碰撞后能量的变化来验证额外维度的存在。如果实验结果显示能量减少,这将是额外维度存在的第一个直接证据。
Outlines
🌌 卡尔萨斯的多维宇宙理论
这段视频脚本介绍了德国数学家卡尔萨斯在1919年提出的大胆而奇特的理论,即我们的宇宙可能不仅仅包含我们熟知的三个空间维度。卡尔萨斯提出,除了左右、前后和上下之外,可能还存在我们尚未观察到的其他空间维度。尽管这个想法当时看似离奇,但它对20世纪的物理学产生了重大影响,并继续影响着当今的前沿研究。视频还提到了爱因斯坦在1907年对重力的探索,以及他如何发现重力是通过空间本身传递的。卡尔萨斯的想法启发了后续的实验,这些实验可能在未来几年内揭示其正确与否。
🔍 额外维度的探索与理论
视频的第二段深入探讨了卡尔萨斯理论的后续发展。卡尔萨斯试图用额外的空间维度来描述电磁力,他设想如果存在第四个空间维度,电磁力就可以用这个维度中的弯曲和扭曲来解释。当他将这个想法写成数学方程时,意外地发现了一个描述电磁力的方程,这让他非常兴奋。然而,这个理论在细节上存在问题,例如无法正确解释电子的质量。直到20世纪中叶,这个理论才被重新审视,并在超弦理论中得到了新的生命。超弦理论试图回答一个基本问题:构成我们周围一切的基本、不可分割的组成部分是什么?
🎻 弦理论与基本粒子的构成
第三段视频脚本详细阐述了弦理论的基本概念,即所有物质和自然界的力都可以归结为振动的弦。在这个理论中,深入到物质的微观层面,我们会发现传统粒子物理学的终点——夸克和轻子内部,存在着类似能量弦的结构。这些弦的不同振动模式对应着不同的基本粒子,从而构成了我们周围的世界。这个理论的关键在于,它提供了一个统一的框架,将物质粒子和力的粒子统一为同一实体的不同表现形式。
🔬 测试额外维度的可能性
视频的最后一部分讨论了如何可能直接测试额外维度的存在。首先,它解释了额外维度可能对宇宙的基本参数产生影响,这些参数包括粒子的质量、重力和电磁力的强度等。弦理论认为,这些参数的特定值可能与额外维度的几何形状有关。此外,视频还提到了在欧洲核子研究中心(CERN)的大型强子对撞机(LHC)上进行的实验,这些实验可能在未来几年内为我们提供额外维度存在的直接证据。如果实验观察到粒子碰撞后能量的减少,并且这种减少符合特定模式,那么这将是额外维度存在的有力证据。
Mindmap
Keywords
💡Theodor Kaluza
💡额外维度
💡爱因斯坦
💡广义相对论
💡电磁力
💡超弦理论
💡维度的几何结构
💡粒子物理学
💡大型强子对撞机
💡宇宙的精细调谐
Highlights
1919年,一位鲜为人知的德国数学家Theodor Kaluza提出了一个大胆而奇特的想法,即我们的宇宙可能实际上拥有超过三个维度的空间。
除了我们熟知的左右、前后、上下三个空间维度外,Kaluza提出可能存在我们尚未看到的空间维度。
尽管这个想法当时看起来古怪,但它对20世纪的物理学产生了重大影响,并继续影响着许多前沿研究。
爱因斯坦在1907年发现了特殊相对论后,决定开始一个新项目,试图完全理解广泛而深远的重力力量。
牛顿在17世纪晚期提出了重力理论,很好地描述了行星、月球等的运动,但爱因斯坦意识到牛顿遗漏了一些关于重力如何实际工作的内容。
爱因斯坦发现,传递重力的介质是空间本身。当空间中存在物质,如太阳时,它会导致空间结构发生弯曲,从而传递重力。
1919年通过天文观测验证了爱因斯坦关于重力的理论,这使爱因斯坦在世界范围内获得了声誉。
Kaluza试图用额外的空间维度来描述当时已知的另一种力量——电磁力。
Kaluza的理论与爱因斯坦的相对论相结合,意外地得出了一个描述电磁力的新方程。
尽管Kaluza的发现令人兴奋,但实际应用中存在问题,例如无法正确计算电子的质量。
1926年,Oskar Klein提出了维度可能以大的容易看到和微小卷曲的形式存在,微小到我们看不见。
超弦理论是一种尝试回答世界基本构成要素是什么的理论,它提出所有物质和力量都来源于振动的能量弦。
超弦理论只有在一个具有十个空间维度和一维时间的宇宙中才有效。
超弦理论提出,我们宇宙的微观结构是由大量微小的、振动的能量弦构成的。
超弦理论可能解释了为什么宇宙中的某些基本参数具有它们特定的值。
在CERN的瑞士日内瓦,正在建造的大型强子对撞机可能在未来几年内测试额外维度的存在。
通过粒子碰撞实验,科学家们希望能够探测到额外维度的存在,这将是物理学史上的重大突破。
从牛顿的绝对空间到爱因斯坦的弯曲空间,再到超弦理论的多维宇宙,我们对宇宙的理解正在不断深化和扩展。
Transcripts
in the year 1919 a virtually unknown
German mathematician named Theodor
Kaluza suggested a very bold and in some
ways very bizarre idea he proposed that
our universe might actually have more
than the three dimensions that we are
all aware of that is in addition to
left-right back-forth and up-down gluts
to propose that there might be
additional dimensions of space that for
some reason we don't yet see now when
someone makes a bold and bizarre idea
sometimes that all it is both bizarre
but has nothing to do with the world
around us this particular idea however
although we don't yet know whether it's
right or wrong and at the end I'll
discuss experiments which in the next
few years may tell us whether it's right
or wrong this idea has had a major
impact on physics in the last century
and continues to inform a lot of
cutting-edge research so I'd like to
tell you something about the story of
these extra dimensions so where do we go
to begin need a bit of backstory go to
1907 this is a year when Einstein is
masking the glow of having discovered
the special theory of relativity and
decides to take on a new project to try
to understand fully the grand pervasive
force of gravity and in that moment
there were many people around who
thought that that project had already
been resolved Newton had given the world
the theory of gravity late 1600s that
works well describes the motion of
planets the motion of the moon and so
forth the motion of apocryphal apples
falling from trees hitting people in the
head all of that could be described
using Newton's work but Einstein
realized that Newton had left something
out of the story because even Newton had
written that although he understood how
to calculate the effect of gravity he
had been unable to figure out how it
really works how is it that the Sun 93
million miles away somehow defect
the motion of the earth how does the Sun
reach out across empty inert space and
exert influence and that as a task to a
Jain Stein set himself to figure out how
gravity works and let me show you what
it is that he found so Einstein found
that the medium that transmits gravity
is space itself the idea goes like this
imagine space is a substrate of all
there is Einstein said space is nice and
flat if there's no matter present but if
there is matter in the environment such
as the Sun it causes the fabric of space
to warp to curve and that communicates
the force of gravity even the earth
warps space around it now look at the
moon the moon is kept in orbit according
to these ideas because it rolls along a
valley in the curved environment that
the Sun and the moon and the earth can
all create by virtue of their presence
we go to a full frame view of this the
earth itself is kept in orbit because it
rolls along a valley in the environment
that's curved because of the sun's
presence that is this new idea about how
gravity actually works now this idea was
tested in 1919 through astronomical
observations it really works it
describes the data and this gained
Einstein prominence around the world and
that is what got Colusa thinking he like
Einstein was in search of what we call a
unified theory that's one theory that
might be able to describe all of
nature's forces from one set of ideas
one set of principles one master
equation if you will so Coolidge's said
to himself
Einstein has been able to describe
gravity in terms of warps and curves in
space in fact space and time to be more
precise maybe I can play the same game
with the other known force which was at
that time known as the electromagnetic
force we know of others today but at
that time that was the only other one
people were thinking about you know the
force responsible for electricity and
magnetic attraction and so forth so
Colusa says maybe I can play the same
game and describe electromagnetic force
in terms of warps and curves
that raised a question warps and curves
in what Einstein had already used up
space and time warps and curves to
describe gravity didn't seem to be
anything else to warp a curve so Colusa
said well maybe there are more
dimensions of space
he said if I want to describe one more
force maybe I need one more dimension so
he imagined that the world had four
dimensions of space not three and
imagine that electromagnetism was warps
and curves in that fourth dimension now
here's the thing when he wrote down the
equations describing warps and curves in
the universe with four space dimensions
not three he found the old equations
that einstein had already derived in
three dimensions those were for gravity
but he found one more equation because
of the one more dimension and when he
looked at that equation it was none
other than the equation that scientists
had long known to describe the
electromagnetic force amazing it just
popped out he was so excited by this
realization that he ran around his house
screaming victory that he had found the
unified theory now clearly Colusa was a
man who took theory very seriously he in
fact there's a story that when he wanted
to learn how to swim he read a book a
treatise on swimming then toven to the
ocean this is a man who would risk his
life on theory now but for those of us
who are a little bit more practically
minded to questions immediately arise
from his observation number one if there
are more dimensions of space where are
they we don't seem to see them and
number two does this theory really work
in detail when you try to apply it to
the world around us now the first
question was answered in 1926 by a
fellow named Oskar Klein
he suggested that dimensions might come
in two varieties there might be big easy
to see dimensions but there might also
be tiny curled up dimensions curled up
so small even though they're all around
us that we don't see them let me show
you that one visually so imagine you're
looking at something like a cable
supporting a traffic lights in Manhattan
in Central Park that's it's kind of
irrelevant but the cable looks
one-dimensional from a distant viewpoint
but you and I all know that it does have
some thickness it's very hard to see it
though from far away but if we zoom in
and take their perspective to say a
little ant walking around little ants
are so small that they can access all
the dimensions the long dimension but
also this clockwise counterclockwise
direction and I hope you appreciate this
it took so long to get these ants to do
this but this illustrates the fact that
dimensions can be of two sorts big and
small and the idea is that maybe the big
dimensions around us are the ones that
we can easily see but there might be
additional dimensions curled up sort of
like the circular part of that cable so
small that they have so far remained
invisible let me show you what that
would look like so if we take a look say
at space itself I can only show of
course two dimensions on a screen some
of you guys will fix that one day but
anything that's not flat in the screen
is a new dimension goes smaller smaller
smaller and way down in the microscopic
depths of space itself this is the idea
you could have additional curled up
dimensions here is a little shape of a
circle so small that we don't see them
but if you were a little
ultra-microscopic ant walking around you
can walk in the big dimensions that we
all know about that's like the grid part
but you could also access the tiny
curled up dimension that's so small that
we can't see with the naked eye or even
with any of our most refined equipment
but deeply tucked into the fabric of
space itself the idea is there could be
more dimensions as we see there now
that's an explanation about how the
universe could have more dimensions than
the ones that we see but what about the
second question that I asked does the
theory actually work when you try to
apply it to the real world well it turns
out that Einstein includes and many
others worked on trying to refine this
framework and apply it to the physics of
the universe as was understood at the
time and in detail it didn't work in
detail for instance they couldn't get
the mass of the electron to work out
correctly in this theory so many people
worked on it but by the 40s certainly by
the 50s
this strange but very compelling idea of
how to unify the laws of physics had
gone away until something wonderful
happened in our age in our era a new
approach to unify the laws of physics is
being pursued by physicists such as
myself many others around the world it's
called super string theory as you were
indicating and the wonderful thing is
that super string theory has nothing to
do at first sight with this idea of
extra dimensions but when we study super
string theory we find that it resurrects
the idea in a sparkling new form so let
me just tell you how that goes super
string theory what is it
well it's a theory that tries to answer
the question what are the basic
fundamental indivisible uncuttable
constituents making up everything in the
world around us the idea is like this so
imagine we look at a familiar object
just a candle and a holder and imagine
that we want to figure out what it is
made of so we go on a journey deep
inside the object and examine the
constituents so deep inside we all know
you go sufficiently far down you have
atoms we also all know that atoms are
not the end of the story
they have little electrons that swarm
around a central nucleus with neutrons
and protons even the neutrons and
protons have smaller particles inside of
them known as quarks that is where
conventional ideas stop here is the new
idea of string theory deep inside any of
these particles there is something else
there's something else is this dancing
filament of energy it looks like a
vibrating string that's where the idea
of string theory comes from and just
like the vibrating strings that you just
saw on a cello can vibrate in different
patterns these can also vibrate in
different patterns they don't produce
different musical notes rather they
produce the different particles making
up the world around us so these ideas
are correct this is what the
ultra-microscopic landscape of the
universe looks like it's built up of a
huge number of these little tiny
filaments of vibrating energy vibrating
in different frequencies the different
frequencies produce the different
particles the different particles are
responsible for all the richness
in the world around us and there you see
unification because matter particles
electrons and quarks radiation particles
photons
gravitons are all built up from one
entity so matter and the forces of
nature all are put together under the
rubric of vibrating strings and that's
what we mean by a unified theory and
here is the catch when you study the
mathematics of string there you find
that it doesn't work in a universe that
just has three dimensions of space
it doesn't work in a universe with four
dimensions of space nor 5 nor 6
finally you can study the equations and
show that it works only in a universe
that has ten dimensions of space and one
dimension of time leads us right back to
this idea of Kaluza and Klein that our
world when appropriately described has
more dimensions than the ones that we
see now you might think about that and
say well ok you know if you have extra
dimensions and they're really tightly
curled up yeah perhaps perhaps we won't
see them if they're small enough but you
know if there's a little tiny
civilization of green people walking
around down there you make them small
enough and we won't see them either that
is true one of the other predictions of
string theory no that's not one of the
other predictions of string theory but
it raises the question are we just
trying to hide away these extra
dimensions or do they tell us something
about the world and the remaining time
I'd like to tell you two features of
them first is many of us believe that
these extra dimensions hold the answer
to what perhaps is the deepest question
in theoretical physics theoretical
science and that question is this when
we look around the world as scientists
have done for the last hundred years
there appear to be about 20 numbers that
really describe our universe these are
numbers like the mass of the particles
like electrons and quarks the strength
of gravity the strength of the
electromagnetic force a list of about 20
numbers that have been measured with
incredible precision but nobody has an
explanation for why the numbers have the
particular values that they do now
the string theory often answer not yet
but we believe the answer for why those
numbers have devised they do may rely on
the form of the extra dimensions and the
wonderful thing is if those numbers had
any other values than the known ones the
universe as we know it wouldn't exist
this is a deep question why those
numbers so finely tuned to allow stars
to shine and planets to form when we
recognize that if you fiddle with those
numbers if I had 20 dials up here and
I'll let you come up and fiddle with
those numbers almost any fiddling makes
the universe disappear so can we explain
those twenty numbers and string theory
suggests that those twenty numbers have
to do with the extra dimensions let me
show you how so when we talk about the
extra dimensions in string theory it's
not one extra dimension as in the older
ideas of Kaluza and Klein this is what
string theory says about the extra
dimensions they have a very rich
intertwined geometry this is an example
of something known as a claw be a shape
name isn't all that important but as you
can see the extra dimensions fold in on
themselves and intertwine in a very
interesting shape interesting structure
and the idea is that if this is what the
extra dimensions look like then the
microscopic landscape of our universe
all around us would look like this on
the tiniest of scales when you swing
your hand you'd be moving around these
extra dimensions over and over again but
they're so small that we wouldn't know
it so what is the physical implication
though relevant to those twenty numbers
consider this if you look at the
instrument of French horn notice that
the vibrations of the airstreams are
affected by the shape of the instrument
now in string theory all the numbers are
reflections of the way strings can
vibrate so just as those air streams are
affected by the twists and turns in the
instrument strings themselves will be
affected by the vibrational patterns and
the geometry within which they are
moving so let me bring some strings into
the story and if you watch these little
fellas vibrating around they'll be here
in a second right there notice that the
way they vibrate is affected by the
geometry of the extra dimensions so if
we knew exactly what the extra
dimensions look like we don't yet but if
we
we should be able to calculate the
allowed notes the allowed vibrational
patterns and if we could calculate the
allowed vibrational patterns we should
be able to calculate those 20 numbers
and if the answer that we get from our
calculations agrees with the values of
those numbers that have been determined
through detailed and precise
experimentation this in many ways would
be the first fundamental explanation for
why the structure of the universe is the
way it is now the second issue that I
want to finish up with is how might we
test for these extra dimensions more
directly is this just an interesting
mathematical structure that might be
able to explain some previously
unexplained features of the world or can
we actually test for these extra
dimensions and we think this is I think
very exciting that in the next five
years or so we may be able to test for
the existence of these extra dimensions
here's how it goes in CERN Geneva
Switzerland a machine is being built
called a Large Hadron Collider it's a
machine that will send particles around
a tunnel opposite directions near the
speed of light every so often those
particles will be aimed at each other so
there's a head-on collision the hope is
that if the collision has enough energy
it may act some of the debris from the
collision from our dimensions forcing it
to enter into the other dimensions how
would we know it well we'll measure the
amount of energy after the collision
compare it to the amount of energy
before and if there's less energy after
the collision than before this will be
evidence that the energy has drifted
away and if it drifts away in the right
pattern that we can calculate this will
be evidence that the extra dimensions
are there let me show you that idea
visually so imagine we have a certain
kind of particles called a graviton
that's the kind of debris we expect to
be ejected out if the extra dimensions
are real but here's how the experiment
will go
you take these particles you slam them
together you slam them together and if
we are right some of the energy of that
collision will go into debris that flies
off
into these extra dimensions so this is
the kind of experiment that we will be
looking at in the next five seven to ten
years or so and if this experiment bears
fruit if we see that kind of particle
ejected by noticing that there's less
energy in our dimensions then when we
began this will show that the extra
dimensions are real and to me this is a
really remarkable story and a remarkable
opportunity going back to Newton with
absolute space didn't provide anything
but an arena a stage in which the events
of the universe take place
Einstein comes along and says well space
and time can warp and curve that's what
gravity is and now string theory comes
along and says yes gravity quantum
mechanics electromagnetism all together
in one package but only if the universe
has more dimensions than the ones that
we see and this is an experiment that
may test for them in our lifetime
amazing possibility thank you very much
Browse More Related Video
![](https://i.ytimg.com/vi/TAhbFRMURtg/hq720.jpg)
Theoretical Physicist Brian Greene Explains Time in 5 Levels of Difficulty | WIRED
![](https://i.ytimg.com/vi/BjmPvovl-V4/hq720.jpg)
Is consciousness an illusion? 5 experts explain
![](https://i.ytimg.com/vi/6Px0livk6m8/hq720.jpg?sqp=-oaymwEmCIAKENAF8quKqQMa8AEB-AH-CYAC0AWKAgwIABABGGUgYChJMA8=&rs=AOn4CLCN4Q2d5ugfEEv1g4SLk7b0xUk6UA)
11. Mind vs. Brain: Confessions of a Defector
![](https://i.ytimg.com/vi/ofEav2i1Jzo/hq720.jpg)
Ask physicist Carlo Rovelli - black holes, white holes, and more
![](https://i.ytimg.com/vi/ER4xNhSVJ2c/hq720.jpg)
NVIDIA黃仁勳給年輕人的忠告!你要面對的世界將是這樣子的!不看真的會後悔!
![](https://i.ytimg.com/vi/yQ6VOOd73MA/hq720.jpg?v=6477af2e)
Your Brain: Who's in Control? | Full Documentary | NOVA | PBS
5.0 / 5 (0 votes)