Shadowing-Übung: Making sense of string theory | Brian Greene - Englisch Sprechen Lernen mit YouTube

Reviewer Gisela C.P.

⏸ Pausiert

Geschwindigkeit:

232 Sätze

Wenn Sätze zu kurz oder zu lang sind, klicke auf Edit, um sie anzupassen.

Reviewer Gisela C.P.

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, Kluza proposed 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's all it is.

Bold and bizarre, but it 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, we need a little bit of backstory.

Go to 1907.

This is a year

when Einstein is basking in 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 a theory of gravity in the 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 it affects the motion of the Earth?

How does the Sun reach out across empty, inert space and exert influence?

And that is a task to which Einstein 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 Kaluza 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 Kaluza 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 Kalutzer 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 that didn't seem to be anything else to warp or curve.

So Kalutze 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 a 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, Kalutze was a man who took theory very seriously.

In fact, there's a story that when he wanted to learn how to swim, he read a book, a treatise on swimming, then dove into 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, Two questions immediately arise from his observation.

Number one, if there are more dimensions in 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 Oscar 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 light.

This is in Manhattan, New Central Park, and 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 the perspective of, say, a little ant walking around.

Little ants are so small that they can access all of 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 on the screen as 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 is in 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 could walk in the big dimensions that we all know about.

That's like the grid part.

100

But you could also access the tiny curled-up dimension

101

that's so small that we can't see it with the naked eye or even with any of our most refined equipment.

102

But deeply tucked into the fabric of space itself, the idea is there could be more dimensions, as we see there.

103

Now, that's an explanation about how the universe could have more dimensions than the ones that we see.

104

But what about the second question that I asked?

105

Does the theory actually work when you try to apply it to the real world?

106

Well, it turns out that Einstein, Kluz and many others worked on trying to refine this framework

107

and apply it to the physics of the universe as was understood at the time.

108

And in detail, it didn't work.

109

In detail, for instance, they couldn't get the mass of the electron to work out correctly in this theory.

110

So many people worked on it, but by the 40s, certainly by the 50s,

111

this strange but very compelling idea of how to unify the laws of physics had gone away.

112

Until something wonderful happened in our age.

113

In our era, a new approach to unify the laws of physics is being pursued by physicists such as myself

114

and many others around the world.

115

It's called super string theory, as you were indicating.

116

And the wonderful thing is that super string theory has nothing to do at first sight with this idea of extra dimensions,

117

but when we study super string theory we find that it resurrects the idea in a sparkling new form.

118

So let me just tell you how that goes.

119

Super string theory, what is it?

120

Well, it's a theory that tries to answer the question, what are the basic, fundamental,

121

indivisible, uncuttable constituents making up everything in the world around us?

122

The idea is like this.

123

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.

124

So we go on a journey deep inside the object and examine the constituents.

125

So deep inside we all know you go sufficiently far down, you have atoms.

126

We also all know that atoms are not the end of the story.

127

They have little electrons that swarm around a central nucleus with neutrons and protons.

128

Even the neutrons and protons have smaller particles inside of them known as quarks.

129

That is where conventional ideas stop.

130

Here is the new idea of string theory.

131

Deep inside any of these particles, there is something else.

132

The something else is this dancing filament of energy.

133

It looks like a vibrating string.

134

That's where the idea of string theory comes from.

135

And just like the vibrating strings that you just saw in a cello can vibrate in different patterns, these can also vibrate in different patterns.

136

They don't produce different musical notes.

137

Rather, they produce the different particles making up the world around us.

138

But these ideas are correct.

139

This is what the ultra-microscopic landscape of the universe looks like.

140

It's built up of a huge number of these little tiny filaments of vibrating energy, vibrating in different frequencies.

141

The different frequencies produce the different particles.

142

The different particles are responsible for all the richness in the world around us.

143

And there you see unification.

144

Because matter particles, electrons and quarks, Radiation particles, photons, gravitons are all built up from one entity.

145

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.

146

And here is the catch.

147

When you study the mathematics of string theory, you find that it doesn't work in a universe that just has three dimensions of space.

148

It doesn't work in a universe with four dimensions of space, nor five nor six.

149

Finally, you can study the equations and show

150

that it works only in a universe that has 10 dimensions of space and one dimension of time.

151

It leads us right back to this idea of Kalutzenkline that our world,

152

when appropriately described, has more dimensions than the ones that we see.

153

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 we won't see them if they're small enough,

154

but 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.

155

One of the other predictions of string theory.

156

No, that's not one of the other predictions of string theory.

157

But it raises the question, are we just trying to hide away these extra dimensions, or do they tell us something about the world?

158

And the remaining time, I'd like to tell you two features of them.

159

First is, many of us believe

160

that these extra dimensions hold the answer to what perhaps is the deepest question in theoretical physics, theoretical science.

161

And that question is this.

162

When we look around the world, as scientists have done for the last 100 years, there appear to be about 20 numbers that really describe our universe.

163

These are numbers like the mass of the particles, like electrons and quarks, the strength of gravity, the strength of the electromagnetic force.

164

It's a list of about 20 numbers that have been measured with incredible precision,

165

but nobody has an explanation for why the numbers have the particular values that they do.

166

Now, does string theory often answer?

167

Not yet.

168

But we believe the answer for why those numbers have the

169

values they do may rely on the form of the extra dimensions.

170

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.

171

This is a deep question.

172

Why are those numbers so finely tuned to allow stars to shine

173

and planets to form when we recognize that if you fiddle with those numbers, if I had 20 dials up here and I let you come up and fiddle with those numbers,

174

almost any fiddling makes the universe disappear.

175

So can we explain those 20 numbers?

176

And string theory suggests that those 20 numbers have to do with the extra dimensions.

177

Let me show you how.

178

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.

179

This is what string theory says about the extra dimensions.

180

They have a very rich intertwined geometry.

181

This is an example of something known as a Kolobiao shape.

182

The name isn't all that important.

183

But as you can see, the extra dimensions fold in on themselves and intertwine in a very interesting shape, interesting structure.

184

And the idea The point is that if this is what the extra dimensions look like,

185

then the microscopic landscape of our universe all around us would look like this on the tiniest of scales.

186

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.

187

So what is the physical implication, though, relevant to those 20 numbers?

188

Consider this.

189

If you look at the instrument, a French horn, notice that the vibrations of the airstreams are affected by the shape of the instrument.

190

Now in string theory, all the numbers are reflections of the way strings can vibrate.

191

So just as those air streams are affected by the twists and turns in the instrument,

192

strings themselves will be affected by the vibrational patterns and the geometry within which they are moving.

193

So let me bring some strings into the story.

194

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.

195

So if we knew exactly what the extra dimensions look like, we don't yet, but if we did, we should be able to calculate the allowed notes, the allowed vibrational patterns.

196

And if we could calculate the allowed vibrational patterns, we should be able to calculate those 20 numbers.

197

And if the answer that we get from our calculations

198

agrees with the values of those numbers that have been determined through detailed and precise experimentation,

199

This in many ways would be the first fundamental explanation for why the structure of the universe is the way it is.

200

Now, the second issue that I want to finish up with is how might we test for these extra dimensions more directly?

201

Is this just an interesting mathematical structure that might be able to explain some previously unexplained features of the world?

202

Or can we actually test for these extra dimensions?

203

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.

204

Here's how it goes.

205

In CERN, Geneva, Switzerland, a machine is being built called the Large Hadron Collider.

206

It's a machine that will send particles around a tunnel, opposite directions, near the speed of light.

207

Every so often, those particles will be aimed at each other so there's a head-on collision.

208

The hope is that if the collision has enough energy, it may eject some of the debris from the collision from our dimensions,

209

forcing it to enter into the other dimensions.

210

How would we know it?

211

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,

212

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.

213

Let me show you that idea visually.

214

So imagine we have a certain kind of particle, it's called a graviton.

215

That's the kind of debris we expect to be ejected out if the extra dimensions are real.

216

But here's how the experiment will go.

217

You take these particles, you slam them together, you slam them together, and if we are right,

218

some of the energy of that collision will go into debris that flies off into these extra dimensions.

219

So this is the kind of experiment that we'll be looking at in the next five, seven to ten years or so.

220

And if this experiment bears fruit,

221

if we see that kind of particle ejected by noticing that there's less energy in our dimensions than when we began,

222

this will show that the extra dimensions are real.

223

And to me, this is a really remarkable story and a remarkable opportunity.

224

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.

225

Einstein comes along and says, well, space and time can warp and curve.

226

That's what gravity is.

227

And now, string theory comes along and says, yes, gravity, quantum mechanics, electromagnetism, all together in one package,

228

but only if the universe has more dimensions than the ones that we see.

229

And this is an experiment that may test for them in our lifetime.

230

Amazing possibility.

231

Thank you very much.

232

Thank you.

TRENDING

Beliebt

Was ist die Shadowing-Technik?

Shadowing ist eine wissenschaftlich fundierte Sprachlerntechnik, die ursprünglich für die professionelle Dolmetscherausbildung entwickelt und durch den Polyglotten Dr. Alexander Arguelles populär gemacht wurde. Die Methode ist einfach aber wirkungsvoll: Du hörst englisches Audio von Muttersprachlern und wiederholst es sofort laut — wie ein Schatten, der dem Sprecher mit nur 1–2 Sekunden Verzögerung folgt. Anders als passives Hören oder Grammatikübungen zwingt Shadowing dein Gehirn und deine Mundmuskulatur, gleichzeitig echte Sprachmuster zu verarbeiten und zu reproduzieren. Studien zeigen, dass es Aussprachegenauigkeit, Intonation, Rhythmus, verbundene Sprache, Hörverständnis und Sprechflüssigkeit signifikant verbessert — was es zu einer der effektivsten Methoden für die IELTS Speaking-Vorbereitung und reale englische Kommunikation macht.

☕ Kauf uns einen Kaffee

ShadowingEnglish bleibt 100% kostenlos dank deiner Unterstützung. Server- und KI-Kosten sind hoch — dein Kaffee hält uns am Laufen! 🙏

Über PayPal spenden

ShadowingEnglish.com – Englisch-Shadowing-Übung

Sprich fließend Englisch mit der Shadowing-Technik. Höre nativen YouTube-Videos zu, wiederhole Satz für Satz und baue echte Aussprache und Sprachflüssigkeit auf — weltweit von IELTS-Lernenden genutzt.

Shadowing-Übung: Making sense of string theory | Brian Greene - Englisch Sprechen Lernen mit YouTube

Beliebt

Über diese Lektion

Wichtige Vokabeln & Phrasen

Übungstipps

Was ist die Shadowing-Technik?

Shadowing-Übung: Making sense of string theory | Brian Greene - Englisch Sprechen Lernen mit YouTube

App herunterladen

Über diese Lektion

Wichtige Vokabeln & Phrasen

Übungstipps

Was ist die Shadowing-Technik?