Kind: captions
Language: en
now on Nova
Take A Thrill Ride into a world Stranger
Than science fiction where you play the
game by breaking some rules where a new
view of the universe pushes you beyond
the limits of your wildest imagination
this is the world of string theory a way
of describing every force and all matter
from an atom to Earth to the end of the
galaxies from the birth of time to its
final tick in a single Theory
a Theory of Everything
our guide to this Brave New World is
Brian Greene the best-selling author and
physicist no matter how many times I
come here I never seem to get used to it
can he help us solve the greatest puzzle
of modern physics
that our understanding of the universe
is based on two sets of laws that don't
agree
resolving that contradiction alluded
even Einstein who made it his final
quest
after decades we may finally be on the
verge of a breakthrough
the solution is strings
tiny bits of energy vibrating like the
strings on a cello a cosmic Symphony at
the heart of all reality
but it comes at a price
parallel universes and 11 Dimensions
most of which you've never seen we
really may live in a universe with more
Dimensions than meet the eye people
who've said that there are extra
dimensions of space have been labeled
crackpots or people who are bananas a
mirage of Science and Mathematics
or the ultimate Theory of Everything
your String Theory fails provide a
testable prediction
then nobody should believe it is that a
Theory of physics or a philosophy one
thing that is certain is that string
theory is already showing us that the
universe may be a lot Stranger than any
of us ever imagined
coming up tonight
it all started with an apple the Triumph
of Newton's equations come from the
quest to understand the planets and the
stars and we've come a long way since
Einstein gave the world a new picture
for what the force of gravity actually
is where he left off
string theorists now dare to go but how
close are they to fulfilling Einstein's
dream watch the elegant Universe right
now
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foreign
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foreign
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of one of the greatest mysteries of
modern science a mystery so profound
that today thousands of scientists on
The Cutting Edge of physics are still
trying to solve it
Albert Einstein spent his last two
decades in this modest home in Princeton
New Jersey
and in his second floor study Einstein
relentlessly sought a single Theory
so powerful it would describe all the
workings of the universe
even as he neared the end of his life
Einstein kept a notepad close at hand
furiously trying to come up with the
equations for what would come to be
known as The Theory of Everything
convinced he was on the verge of the
most important Discovery in the history
of science
Einstein ran out of time his dream
unfulfilled
now almost a half century later
Einstein's goal of unification combining
all the laws of the universe in one
all-encompassing theory has become the
Holy Grail of modern physics
and we think we may at last achieve
Einstein's dream with a new and radical
set of ideas called String Theory but if
this revolutionary theory is right we
are in for quite a shock
String Theory says we may be living in a
universe where reality meets science
fiction
a universe of 11 dimensions
with parallel universes right next door
An Elegant Universe composed entirely of
the music of strings
but for all its ambition the basic idea
of string theory is surprisingly simple
it says that everything in the universe
from the tiniest particle to the most
distant star is made from one kind of
ingredient
unimaginably small vibrating strands of
energy called strings
just as the strings of a cello can give
rise to a rich variety of musical notes
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the tiny strings in string theory
vibrate in a multitude of different ways
making up all the constituents of nature
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in other words the universe is like a
grand Cosmic Symphony resonating with
all the various notes these tiny
vibrating strands of energy can play
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string theory is still in its infancy
but it's already revealing a radically
new picture of the universe
one that is both strange and beautiful
but what makes us think we can
understand all the complexity of the
universe let alone reduce it to a single
theory of everything we have Army new
minus a half Jimmy new R do you remember
how this goes equals eight high G team
you know it comes from varying the
Einstein Hilbert action we get the field
equations and this term remember what
this is called
what
no that's the scalar curvature this is
the Richie tensor
have you been studying this at all
no matter how hard you try
you can't teach physics to a dog
their brains just aren't wired to grasp
it
but what about us
how do we know that we're wired to
comprehend the deepest laws of the
universe
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well physicists today are confident that
we are
and we're picking up where Einstein left
off in his quest for unification
would be
formulation of a law that describes
perhaps everything in the known universe
from one single idea one master equation
and we think that there might be this
master equation because throughout the
course of the last 200 years or so our
understanding of the universe has given
us a variety of explanations that are
all pointing towards one spot they seem
to all be converging on one nugget of an
idea that we're still trying to find
unification is where it's at
unification is what we're trying to
accomplish the whole aim of fundamental
physics is to is to see more and more of
the world's phenomena in terms of fewer
and fewer and simpler and simpler
principles
we feel as physicists that if we can
explain a wide number phenomena in a
very simple manner that that somehow
progress
There is almost an emotional aspect to
the way in which the great theories in
physics sort of encompass
a wide variety of apparently different
physical phenomena
so this idea that we should be aiming to
unify our understanding is inherent
essentially to the whole way in which
this kind of science progresses
and long before Einstein the Quest for
unification began with the most famous
accident in the history of science
as The Story Goes one day in 1665 a
young man was sitting under a tree when
all of a sudden he saw an apple fall
from above and with the fall of that
Apple Isaac Newton revolutionized our
picture of the universe
in an audacious proposal for his time
Newton proclaimed that the force pulling
apples to the ground
and the force keeping the moon in orbit
around the Earth were actually one and
the same
in one Fell Swoop
Newton unified the heavens
and the Earth
in a single theory he called gravity
the unification of the celestial with
the terrestrial that the same laws that
govern the planets in their motions
govern the tides and the falling of
fruit here on Earth it was a fantastic
unification of our picture of nature
gravity was the first force to be
understood scientifically though three
more would eventually follow and
although Newton discovered his law of
gravity more than 300 years ago his
equations describing this Force make
such accurate predictions that we still
make use of them today
in fact scientists needed nothing more
than Newton's equations to plot the
course of a rocket that landed men on
the moon
yet there was a problem
while his laws described the strength of
gravity with great accuracy Newton was
harboring an embarrassing Secret
he had no idea how gravity actually
works
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for nearly 250 years scientists were
content to look the other way when
confronted with this mystery
but in the early 1900s an unknown clerk
working in the Swiss patent office would
change all that
while reviewing patent applications
Albert Einstein was also pondering the
behavior of light
and little did Einstein know that his
musings on light would lead him to solve
Newton's mystery of what gravity is
[Music]
26. Einstein made a startling discovery
that the velocity of light
is a kind of cosmic speed limit a speed
that nothing in the universe can exceed
but no sooner had the Young Einstein
published this idea then he found
himself squaring off
with the father of gravity
the trouble was the idea that nothing
can go faster than the speed of light
flew in the face of Newton's picture of
gravity
to understand this conflict
we have to run a few experiments
and to begin with let's create a cosmic
catastrophe imagine that all of a sudden
and without any warning the sun
vaporizes and completely disappears
now let's Replay that catastrophe and
see what effect it would have on the
planets according to Newton
Newton's theory predicts that with the
destruction of the Sun
the planets would immediately fly out of
their orbits
careening off into space
in other words Newton thought that
gravity was a force that acts
instantaneously across any distance and
so we would immediately feel the effect
of the sun's destruction but Einstein
saw a big problem with Newton's Theory
a problem that arose from his work with
light
Einstein knew light doesn't travel
instantaneously
in fact it takes eight minutes for the
sun's Rays to travel the 93 million
miles to the Earth
and since he had shown that nothing not
even gravity can travel faster than
light
how could the Earth be released from
orbit
before the darkness resulting from the
sun's disappearance
reached our eyes
to the young upstart from the Swiss
patent office anything outrunning light
was impossible
and that meant that 250 year old
Newtonian picture of gravity was wrong
if Newton is wrong
then why do the planet stay of it
because remember the Triumph of Newton's
equations come from the quest to
understand the planets and the stars in
particular the problem of why do the
planets have the orbits that they do
and with Newton's equations you can
calculate the way that the planets will
move
Einstein's got to resolve this dilemma
in his late 20s Einstein had to come up
with a new picture of the universe in
which gravity does not exceed the cosmic
speed limit
still working his day job in the patent
office Einstein embarked on a solitary
quest to solve this mystery
after nearly 10 years of racking his
brain he found the answer in a new kind
of unification
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Einstein came to think of the three
dimensions of space
and the single dimension of time
as bound together in a single fabric of
space-time
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it was his hope that by understanding
the geometry of this four-dimensional
fabric of space-time
that he could simply talk about things
moving along surfaces in this space-time
fabric
like the surface of a trampoline this
unified fabric is Warped and stretched
by heavy objects like planets and stars
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and it's this warping or curving of
space-time that creates what we feel as
gravity
a planet like the Earth is kept in orbit
not because the Sun reaches out and
instantaneously grabs hold of it as a
Newton's Theory but simply because it
follows Curves in the spatial fabric
caused by the sun's presence so with
this new understanding of gravity let's
re-run the cosmic catastrophe let's see
what happens now if the sun disappears
the gravitational disturbance that
results will form a wave that travels
across the spatial Fabric in much the
same way that a pebble dropped into a
pond makes ripples that travel across
the surface of the water so we wouldn't
feel a change in our orbit around the
sun until this wave reached the Earth
what's more Einstein calculated that
these ripples of gravity travel at
exactly the speed of light
and so with this new approach Einstein
resolved the conflict with Newton over
how fast gravity travels and more than
that Einstein gave the world a new
picture for what the force of gravity
actually is its warps and curves
in the fabric of space and time
Einstein called this new picture of
gravity general relativity
and within a few short years Albert
Einstein became a household name
Einstein was like a rock star in his day
he was one of the most widely known and
recognizable figures alive he and
perhaps Charlie Chaplin were the
reigning Kings of the popular media
people followed his work and they were
anticipating because of this wonderful
thing he had done with general
relativity
this
recasting the laws of gravity out of his
head
there was the thought he could do it
again and they you know people want to
be in on that
despite all that he had achieved
Einstein wasn't satisfied he immediately
set a sights on an even grander goal the
unification of his new picture of
gravity with the only other Force known
at the time electromagnetism
now electromagnetism is a force that had
itself been unified only a few decades
earlier
in the mid-1800s electricity
and magnetism were sparking scientists
interest
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these two forces seem to share a curious
relationship that inventors like Samuel
Morse were taking advantage of in
newfangled devices such as the telegraph
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an electrical pulse sent through a
telegraph wire to a magnet thousands of
miles away
produce the familiar dots and dashes of
Morse code that allowed messages to be
transmitted across the continent
in a fraction of a second
although the telegraph was a sensation
the fundamental science driving it
remained something of a mystery
foreign
but to a Scottish scientist named James
Clark Maxwell
the relationship between electricity and
magnetism
was so obvious in nature
that it demanded unification
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if you've ever been on top of a mountain
during a thunderstorm you'll get the
idea of how electricity and magnetism
are closely related
when a stream of electrically charged
particles flows like in a bolt of
lightning it creates a magnetic field
and you can see evidence of this on a
compass
obsessed with this relationship the
Scott was determined to explain the
connection between electricity and
magnetism in the language of mathematics
casting new light on the subject Maxwell
devised a set of four elegant
mathematical equations
foreign
that unified electricity and magnetism
in a single Force called
electromagnetism
and like Isaac Newton before him
Maxwell's unification took science a
step closer to cracking the code of the
universe
that was really the remarkable thing
that these different phenomena were
really connected in this way
and it's another example of diverse
phenomena coming from a single
underlying
building block or a single underlying
principle
isn't that
golf
it has to do with electricity and
magnetism can all be
four very simple equations
isn't that incredible
is that amazing I call that elegant
Einstein thought that this was a one of
the triumphant moments of all of physics
and admired Maxwell hugely for what he
had done
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about 50 years after Maxwell unified
electricity and magnetism Einstein was
confident that if he could unify his new
theory of gravity with Maxwell's
electromagnetism he'd be able to
formulate a master equation that could
describe everything the entire universe
Einstein clearly believes that the
Universe has an overall Grand and
beautiful pattern to the way that it
works and so to ask the question why was
he looking for the unification I think
the answer is simply that Einstein is
one of those physicists who
really wants to know the mind of God
which means the entire picture
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today
this is the goal of string theory
to unify our understanding of everything
from the birth of the universe
to The Majestic swirl of galaxies in
just one set of principles
one master equation
all right
Newton had unified the heavens and the
Earth
in the theory of gravity
Maxwell had unified electricity and
magnetism
Einstein reasoned all that remained to
build a Theory of Everything a single
theory that could Encompass all the laws
of the universe was to merge his new
picture of gravity with electromagnetism
certainly had motivation probably one of
them might have been Aesthetics or this
quest to simplify another one might have
been just the physical fact that it
seems like the speed of gravity is equal
to the speed of light
so if they both go at the same speed
then maybe that's an indication of some
underlying symmetry
but as Einstein began trying to unite
gravity and electromagnetism
he would find that the difference in
strength between these two forces would
outweigh their similarities
let me show you what I mean
we tend to think that gravity is a
powerful force
after all it's the force that right now
is anchoring me to the Sledge
but compared to electromagnetism it's
actually terribly feeble in fact there's
a simple little test to show this
imagine that I was to LEAP from this
rather tall building
actually let's not just imagine it let's
do it you'll see what I mean
[Music]
[Applause]
now
of course I really should have been
flattened but the important question is
what kept me from crashing through the
sidewalk and hurtling right down to the
Center of the Earth
well strange as it sounds the answer is
electromagnetism
everything we can see from you and me to
the sidewalk is made of tiny bits of
matter called atoms
and the outer shell of every atom
contains a negative electrical charge
so when my atoms collide with the atoms
in the cement these electrical charges
repel each other with such strength that
just a little piece of sidewalk can
resist the entire Earth's gravity and
stop me from falling
in fact the electromagnetic force is
billions and billions of times stronger
than gravity
that seems a little strange because
gravity keeps our feet to the ground it
keeps the earth going around the Sun but
in actual fact it manages to do that
only because it acts on huge enormous
conglomerates of matter you know you me
the Earth the Sun but really at the
level of individual atoms gravity is a
really incredibly feeble tiny Force
it would be an uphill battle for
Einstein to unify these two forces of
wildly different strengths
and to make matters worse barely had he
begun before sweeping changes in the
world of physics would leave him behind
Einstein had achieved so much in the
Years up to about 1920 that he naturally
expected that he could go on
by playing the same theoretical games
and go on achieving great things and he
couldn't
nature revealed itself in other ways and
in the 1920s and 1930s and the
particular tricks and tools that
Einstein had at this disposal that had
been so fabulously successful
weren't applicable anymore
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you see in the 1920s a group of young
scientists stole the spotlight from
Einstein when they came up with an
outlandish new way of thinking about
physics
their vision of the universe
was so strange it makes science fiction
look tame and it turned Einstein's quest
for unification on its head unification
unification
led by Danish physicist Niels Bohr these
scientists were uncovering an entirely
new realm of the universe
atoms long thought to be the smallest
constituents of nature
were found to consist of even smaller
particles the now familiar nucleus of
protons and neutrons orbited by
electrons
and the theories of Einstein and Maxwell
were useless at explaining the bizarre
way these tiny bits of matter interact
with each other inside the atom
there was a tremendous mystery about how
to account for all this how to account
for what was happening to the nucleus as
the atom began to be pried apart in
different ways
and the old theories were totally
inadequate to the task of explaining
them gravity was irrelevant it was far
too weak and electricity and magnetism
was not sufficient
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without a theory to explain this strange
new world
these scientists were lost in an
unfamiliar Atomic territory
looking for any recognizable landmarks
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[Applause]
then in the late 1920s all that changed
during those years physicists developed
a new Theory called quantum mechanics
and it was able to describe the
microscopic realm with great success
here's the thing
quantum mechanics was so radical a
theory that it completely shattered all
previous ways of looking at the universe
Einstein's theories demand that the
universe is orderly and predictable
but Niels Bohr disagreed
he and his colleagues proclaimed that at
the scale of atoms and particles the
world is a game of chance
at the atomic or Quantum level
uncertainty rules
the best you can do according to Quantum
Mechanics is predict the chance or
probability of one outcome or another
and this strange idea thanks
open the door to an unsettling new
picture of reality
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it was so unsettling that if the bizarre
features of quantum mechanics were
noticeable in our everyday world like
they are here in the quantum Cafe
you might think you'd lost your mind the
laws in the quantum world are very
different
from the laws that we are used to our
daily experiences are totally different
from anything that you would see in the
quantum world the quantum world is crazy
is probably the best way to put it it's
a crazy world
for nearly 80 years quantum mechanics
has successfully claimed that the
strange and bizarre are typical of how
our universe actually behaves on
extremely small scales
at the scale of everyday life we don't
directly experience the weirdness of
quantum mechanics
but here in the quantum Cafe big
everyday things sometimes behave as if
they were microscopically tiny
and no matter how many times I come here
I never seem to get used to it
I'll have an orange juice please
I'll try I'll try she says
[Music]
you see they're not used to people
placing definite orders here in the
quantum Cafe because here everything is
ruled by tents while I'd like an orange
juice there's only a particular
probability that I'll actually get one
and there's no reason to be disappointed
with one particular outcome or another
because quantum mechanics suggests that
each of the possibilities like getting a
yellow juice or a red juice may actually
happen they just happen to happen in
universes that are parallel to ours
universes that seem as real to their
inhabitants as our universe seems to us
if there are a thousand possibilities
and quantum mechanics cannot with
certainty say which of the thousands it
will be
then all thousands will happen
yeah you can laugh at it and say well
that has to be wrong
but there are so many other things in
physics which at the time that people
came up with had to be wrong but it
wasn't
I need to be a little careful I think
before you say this is completely wrong
and even in our own Universe Quantum
mechanic says there's a chance
that things we'd ordinarily think of as
impossible
can actually happen
for example there's a chance that
particles can pass right through walls
or barriers that seem impenetrable to
you or me
there's even a chance that I could pass
through something solid like a wall now
Quantum calculations do show that the
probability for this to happen in the
everyday world is so small that I'd need
to continue walking into the wall for
nearly an eternity before having a
reasonable chance of succeeding
but here these kind of things
happen all the time
you have to learn to abandon those
assumptions that you have about the
world in order to understand quantum
mechanics
in my gut in my belly do I feel like I
have a deep intuitive understanding of
quantum mechanics no
and neither did Einstein
he never lost faith that the Universe
behaves in a certain and predictable way
the idea that all we can do is calculate
the odds that things will turn out one
way or another
with something Einstein deeply resisted
quantum mechanics says that you can't
know for certain the outcome of any
experiment you can only assign a certain
probability to the outcome of any
experiment
and this Einstein disliked intensely he
used to say God does not throw dice
experiment
after experiment
showed Einstein was wrong and that
quantum mechanics really does describe
how the world works at the subatomic
level
so quantum mechanics is not a luxury
something that you can do without
I mean why is water the way it is why
does light go straight through water why
is it transparent why are other things
not transparent how do molecules form
why are they reacting the way they react
the moment that you want to understand
anything
at an atomic level
as non-intuitive as it is
at that moment you can only make
progress with quantum mechanics
quantum mechanics is fantastically
accurate there has never been a
prediction of quantum mechanics that is
contradicted an observation
never
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by the 1930s Einstein's quest for
unification was floundering
while quantum mechanics was unlocking
the secrets of the atom
scientists found that gravity and
electromagnetism are not the only forces
ruling the universe
probing the structure of the atom they
discovered two more forces
one dubbed the strong nuclear force acts
like a super glue holding the nucleus of
every atom together binding protons to
neutrons
and the other called the weak nuclear
force allows neutrons to turn into
protons giving off radiation in the
process
at the quantum level the force we're
most familiar with gravity was
completely overshadowed by
electromagnetism and these two new
forces
now the strong and weak forces may seem
obscure but in one sense at least we're
all very much aware of their power
5 29 on the morning of July 16 1945 that
power was revealed by an act that would
change the course of history
in the middle of the desert in New
Mexico at the top of a steel Tower about
100 feet above the top of this Monument
the first atomic bomb was detonated it
was only about five feet across but that
bomb packed a punch equivalent to about
20 000 tons of TNT
[Music]
with that powerful explosion scientists
unleashed the strong nuclear force the
force that keeps neutrons and protons
tightly glued together inside the
nucleus of an atom
by breaking the bonds of that glue and
splitting the atom apart
vast truly unbelievable amounts of
destructive energy were released
we can still detect remnants of that
explosion through the other nuclear
force the weak nuclear force because
it's responsible for radioactivity
and today more than 50 years later the
radiation levels around here are still
about 10 times higher than normal
so although in comparison to
electromagnetism and gravity the nuclear
forces act over very small scales their
impact on everyday life is every bit as
profound
[Music]
but what about gravity Einstein's
general relativity where does that fit
in at the quantum level
quantum mechanics tells us how all of
Nature's forces work in the microscopic
realm except for the force of gravity
absolutely no one could figure out how
gravity operates when you get down to
the size of atoms and subatomic
particles that is no one could figure
out how to put general relativity and
quantum mechanics together into one
package
for decades every attempt to describe
the force of gravity in the same
language as the other forces the
language of quantum mechanics
has met with disaster
you try to put those two pieces of
mathematics together they do not coexist
peacefully
you've got answers that the
probabilities of the event you're
looking at are infinite nonsense it's
not profound it's just nonsense it's
very ironic because it was the first
Force to actually be understood in some
decent quantitative way but uh but but
it still remains
um uh split off and very different from
from from from the other ones the laws
of nature are supposed to fly everywhere
so if Einstein's laws are supposed to
apply everywhere
and the laws of quantum mechanics are
supposed to apply everywhere
well you can't have two separate
everywhere
[Music]
in 1933 after fleeing Nazi Germany
Einstein settled in Princeton New Jersey
working in solitude he stubbornly
continued the quest he had begun more
than a decade earlier tonight gravity
and electromagnetism
[Music]
every few years headlines appeared
proclaiming Einstein was on the verge of
success
but most of his colleagues believed his
quest was misguided and that his best
days were already behind him
Einstein in his later years got rather
detached from the work of physics in
general and and stopped reading people's
papers I didn't even think he knew there
was such a thing as the weak nuclear
force he didn't pay attention to those
things he kept working on the same
problem that he had started working on
as a younger man
when the community of theoretical
physicists began to probe the atom
Einstein very definitely gets left out
of the picture
he in some sense chooses not to look at
the physics coming from these
experiments
that means that the laws of quantum
mechanics
Play No role in his sort of further
investigations
he's thought to be this daughtery
sympathetic old figure who led an
earlier Revolution but somehow fell out
of it
it is as if a general
who was the master of horse cavalry
who has achieved great things as the
commander at the beginning of the first
World War
would try to bring mounted Cavalry into
play against the barbed wire trenches
and machine guns of the other side
Albert Einstein died on April 18 1955.
and for many years it seemed that
Einstein's dream of unifying the forces
in a single Theory died with him
so the Quest for unification becomes a
Backwater of physics by the time of
Einstein's death in the 50s
almost no serious physicists are engaged
in this quest for unification
[Music]
in the years since physics split into
two separate camps one that uses general
relativity to study big and heavy
objects things like stars galaxies and
the universe as a whole and another that
uses quantum mechanics to study the
tiniest of objects like atoms and
particles
this has kind of been like having two
families that just cannot get along and
never talk to each other
living under the same roof
there just seemed to be no way to
combine quantum mechanics and general
relativity in a single theory that could
describe the Universe on all scales
oh
now in spite of this we've made
tremendous progress in understanding the
universe
but there's a catch
there are strange Realms of the cosmos
that will never be fully understood
until we find a unified theory
and nowhere is this more evident
[Music]
than in the depths of a black hole
[Music]
a German astronomer named Carl
schwartzfield first proposed what we now
call black holes in 1916.
foreign
lines in World War One
solved the equations of Einstein's
general relativity in a new and puzzling
way
between calculations of artillery
trajectories
short Shield figured out that an
enormous amount of mass like that of a
very Dense Star concentrated in a small
area would warp the fabric of space-time
so severely
that nothing not even light could Escape
its gravitational pull
[Music]
for decades physicists were skeptical
that short Shield's calculations were
anything more than Theory
but today
satellite telescopes probing deep into
space
are discovering regions with enormous
gravitational pull
that most scientists believe are black
holes
Schwartz Shield's Theory now seems to be
reality
so here's the question
if you're trying to figure out what
happens in the depths of a black hole
where an entire star is crushed to a
tiny Speck
do you use general relativity because
the star is incredibly heavy
or quantum mechanics because it's
incredibly tiny
well that's the problem
since the center of a black hole is both
tiny and heavy you can't avoid using
both theories at the same time
and when we try to put the two theories
together in the realm of black holes
they conflict it breaks down they give
nonsensical predictions and the universe
is not nonsensical it's got to make
sense
quantum mechanics works really well for
small things on general relativity works
really well for stars and galaxies but
the atoms the small things and the
galaxies they're part of the same
universe so there has to be some
description that applies to everything
so we can't have one description for
atoms and one for stars
now with string theory we think we may
have found a way to unite our theory of
the large and our theory of the small
and make sense of the universe at all
scales and all places
instead of a multitude of tiny particles
String Theory proclaims that everything
in the universe all forces and all
matter is made of one single ingredient
tiny vibrating strands of energy known
as strings
string can wiggle in many different ways
whereas of course a point can't
and the different ways in which the
string Wiggles represent the different
kinds of Elementary particles it's like
a violin string
and it can vibrate just like violin
strings can vibrate
each note if you like describes a
different particle
so it has incredible unification power
it unifies our understanding of all
these different kinds of particles
so Unity of the different forces and
particles is achieved because they all
come from different kinds of vibrations
of the same basic string
it's a simple idea with far-reaching
consequences
what String Theory does is it holds out
the promise that look we can really
understand questions that you might not
even have thought were scientific
questions questions about how the
universe began why the universe is the
way it is at the most fundamental level
the idea that a scientific theory that
we already have in our hands could
answer the most basic questions is
extremely seductive
but this seductive new theory is also
controversial
strings if they exist are so small
there's little hope of ever seeing one
strength Theory and string theorists do
have a real problem how do you actually
test string theory if you can't test it
in the way that we test normal theories
it's not science it's philosophy and
that's a real problem
the string theory fails to provide a
protestable prediction
then nobody should believe it
on the other hand there's a kind of
Elegance to these things
and given the history of how theoretical
physics has evolved thus far
it is totally conceivable
that some if not all or these ideas will
turn out to be correct
I think a hundred years from now
this particular period when most of the
brightest young theoretical physicists
worked on string theory will be
remembered as a heroic age when
theorists tried and succeeded to develop
a unified theory of all the phenomenon
of nature on the other hand it may be
remembered as a tragic failure my guess
is that it'll be something like the
former rather than the latter
uh but asked me 100 years from now then
I can tell you
our understanding of the universe has
come an enormously Long Way during the
last three centuries
just consider this
Isaac Newton who's perhaps the greatest
scientist of all time once said I have
been like a boy
playing on the seashore diverting myself
in now and then finding a smoother
Pebble or prettier shell than usual
while the great ocean of Truth laid
before me all undiscovered
and yet 250 years later Albert Einstein
who was Newton's true successor was able
to seriously suggest that this vast
ocean all the laws of nature might be
reduced to a few fundamental ideas
expressed by a handful of mathematical
symbols
and today a half century after
Einstein's death we may at last be on
the verge of fulfilling his dream of
unification
with string theory
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but where do this daring and strange new
Theory come from
how does string theory achieve the
ultimate unification of the laws of the
large and the laws of the small
and how will we know if it's right or
wrong no experiment can ever check up
what's going on at the distances that
are being studied the theory is
permanently safe
is that a Theory of physics
or a philosophy it isn't written in the
stars that we're going to succeed but in
the end
we hope we will have a single theory
that governs everything
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good morning
foreign
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