Atomic Expert Explains "Oppenheimer" Bomb Scenes | WIRED

Summary

This video script delves into the historical and scientific aspects of the first atomic bomb, focusing on the Trinity test and its implications. It details the meticulous assembly process, the implosion technique, and the potential risks, including atmospheric ignition. The script also touches on the psychological impact of the bomb's detonation and the ethical dilemmas faced by Oppenheimer, highlighting the paradox of pursuing peace through destructive means.

Takeaways

• 🔬 The script discusses the science behind the development of the atomic bomb and the role of J. Robert Oppenheimer.
• 💥 It describes the assembly process of the 'gadget', the first atomic bomb, using high explosive lenses to compress a plutonium core.
• 🍑 The plutonium core is compared to the size of a grapefruit, highlighting the small size of such a powerful weapon.
• 🔍 Detailed descriptions of the implosion process, including the use of a polonium-beryllium sphere to initiate the nuclear reaction.
• 🎥 The script references actual historical footage and photos, emphasizing the authenticity of the depicted assembly and testing process.
• 🏜️ The importance of a controlled environment during the final assembly is stressed, to prevent any deformation of the shock wave.
• 💰 The value of the tamper plug and the delicate operation of placing it around the plutonium core is highlighted, indicating the high stakes involved.
• 🌡️ The script mentions the heat generated by the radioactive plutonium core, adding to the complexity of handling the material.
• 🔌 The necessity of precise timing for the electrical signals to detonate the bomb is explained, emphasizing the technical challenges.
• 👀 The use of welding goggles by Oppenheimer during the Trinity test to protect against the intense brightness of the explosion.
• 🌆 The psychological impact of the bomb's detonation is considered, with the script mentioning the recommendation to drop bombs on Japan at night for maximum effect.

Q & A

What is the historical significance of the 'gadget' mentioned in the script?

The 'gadget' refers to the first atomic bomb, which was assembled and tested during the Manhattan Project. Its successful detonation at the Trinity test site marked a significant milestone in nuclear weapons development and World War II history.

What were the explosive lenses made of, as described in the script?

The explosive lenses were made of variants of TNT, which were used to symmetrically compress the plutonium sphere at the heart of the atomic bomb.

Why was the plutonium sphere inside the atomic bomb described as being about the size of a grapefruit?

The comparison to a grapefruit helps to convey the relatively small size of the plutonium sphere, which was crucial for the implosion process to initiate the nuclear chain reaction.

What was the purpose of the polonium and beryllium sphere inside the plutonium?

The polonium and beryllium sphere served as a neutron source. When compressed, it would emit neutrons that would initiate the nuclear fission reaction in the plutonium.

What is the 'implosion' method mentioned in the script?

Implosion is the process by which the atomic bomb's high explosive lenses compress the plutonium core, causing a rapid increase in density and temperature to initiate a nuclear explosion.

Why was the final assembly of the atomic bomb considered so delicate and dangerous?

The final assembly was delicate because it involved handling highly radioactive and valuable materials with extreme precision. It was dangerous due to the increasing risk of accidental detonation and radiation exposure as the bomb neared completion.

What was the tamper plug, and why was its placement so critical?

The tamper plug was a component designed to sit around the plutonium core. Its placement was critical because it affected the efficiency of the explosion and was worth a significant amount of money in 1945, making any mistake during its installation potentially very costly.

Why was the plutonium core so radioactive that it was warm to the touch?

The plutonium core was warm due to the heat generated by its intense radioactivity. The amount of plutonium used in the bomb was sufficient to produce a heat signature of about 80 degrees Fahrenheit.

What was the concern about atmospheric ignition during the Trinity test, and was it ever a realistic threat?

The concern was that the explosion could cause nitrogen and oxygen in the atmosphere to fuse, potentially triggering a global nuclear fusion reaction. However, later calculations showed that this was highly unlikely, requiring conditions far beyond what was possible with the bomb's yield.

Why were the atomic bombs dropped on Japan at night originally recommended, and why were they dropped in the morning instead?

Dropping the bombs at night was intended to maximize the psychological impact due to the brightness of the explosions. However, logistical reasons led to the bombs being dropped in the morning to ensure better visibility for the pilots and accuracy in targeting.

What was the actual yield of the Trinity test, and how did it compare to initial estimates?

The Trinity test yielded the equivalent of 20,000 tons of TNT, which was significantly higher than the initial estimate of 4,000 tons. This demonstrated that the bomb was more powerful than the scientists had anticipated.

What was the scale of the Manhattan Project, and what was its output in terms of material?

The Manhattan Project was a massive industrial endeavor employing around 500,000 people and costing approximately $2 billion. Despite its scale, the output was minimal: a 6-kilogram plutonium core for the Trinity test, and cores for two additional bombs dropped on Hiroshima and Nagasaki.

What were J. Robert Oppenheimer's feelings about the development and use of atomic bombs after World War II?

Oppenheimer felt a complex mix of emotions. He regretted the continued development of more and more powerful weapons post-war, fearing that such a path could ultimately endanger civilization itself. He was aware of the potential for devastating wars involving much more powerful bombs.

Outlines

00:00

🔬 The Science Behind Nuclear Weapon Assembly

This paragraph delves into the technical aspects of assembling a nuclear weapon, focusing on the historical account of the 'gadget' assembled by Oppenheimer's team. The process involves the use of high explosive lenses to compress a plutonium sphere, which is further surrounded by a polonium-beryllium core to initiate the nuclear chain reaction. The assembly's precision is paramount, with the tamper plug being a critical and expensive component. The paragraph also touches on the challenges faced during the final assembly, including the plutonium core's radioactivity and the difficulties encountered with fitting the core due to temperature discrepancies.

05:00

🌌 The Trinity Test: A Historical Milestone

This section of the script recounts the Trinity Test, the first detonation of a nuclear bomb, emphasizing the meticulous documentation and the precautions taken to ensure the test's success. It details the use of nixie tubes for pre-digital number display, the importance of timing in sending high voltage signals to detonators, and the psychological impact of the explosion's brightness. The paragraph also discusses the potential risks of atmospheric ignition and the subsequent reassurances provided by Oppenheimer. The narrative includes descriptions of the bomb's assembly, the test's visual documentation, and the unexpected phenomena observed during the detonation, such as the 'rope trick' effect.

10:01

💥 The Implications of Nuclear Testing and Oppenheimer's Legacy

The final paragraph reflects on the broader implications of nuclear testing, particularly the Trinity Test's role in shaping Oppenheimer's legacy and the future of nuclear weapons. It discusses the scale of the Manhattan Project, its resource consumption, and the output of a small amount of highly potent material. The paragraph further explores Oppenheimer's complex character, his initial optimism about peace through war, and his eventual regret over the proliferation of nuclear weapons and the existential threat they posed to humanity. It concludes with a poignant look at the paradox of Oppenheimer's life and the moral dilemmas inherent in the development of nuclear technology.

Keywords

💡Nuclear Weapons

Nuclear weapons are devices that derive their destructive force from nuclear reactions, either fission or a combination of fission and fusion. They are the most powerful weapons ever created, with the capacity to cause massive destruction and long-term environmental damage. In the video, the focus is on the science behind the creation of the first atomic bomb, highlighting the historical significance and the technical aspects of its assembly and detonation.

💡Oppenheimer

J. Robert Oppenheimer was an American physicist who played a crucial role in the development of the atomic bomb during World War II as the head of the Manhattan Project. The video script discusses his involvement in the Trinity test, the first detonation of a nuclear weapon, and his subsequent reflections on the implications of nuclear warfare for humanity.

💡Implosion

Implosion is the process of inward collapse, and in the context of nuclear weapons, it refers to the method used to compress the fissile material to achieve critical mass and initiate a nuclear chain reaction. The script describes the assembly of the 'gadget' and how explosive lenses are used to compress the plutonium sphere symmetrically to trigger the atomic bomb's explosion.

💡Plutonium

Plutonium is a radioactive chemical element with the symbol Pu and is used as a fuel in nuclear reactors and as the fissile material in nuclear weapons. The script mentions a plutonium sphere as the power source of the atomic bomb, where its compression is essential for the bomb's detonation.

💡Explosive Lenses

Explosive lenses are a type of high explosive shaped and arranged to focus a shock wave onto a specific point, such as the plutonium core in a nuclear weapon. The script describes how these lenses are used to create a symmetrical compression of the plutonium sphere, which is necessary for the successful detonation of the bomb.

💡Detonators

Detonators are devices that produce a small explosive charge to initiate the detonation of more substantial explosives. In the script, the detonators are crucial for starting the shockwave that leads to the compression of the plutonium and the subsequent nuclear explosion.

💡Polonium and Beryllium

Polonium and beryllium are elements used in nuclear weapons to create a neutron source. When compressed, as described in the script, they can emit neutrons that initiate the nuclear chain reaction. The script mentions a tiny sphere of polonium and beryllium at the center of the plutonium, which plays a critical role in starting the atomic bomb's reaction.

💡Tamper Plug

A tamper plug is a component in a nuclear weapon designed to surround the core and increase the efficiency of the explosion by reflecting the shock wave back into the core. The script describes the delicate operation of placing the tamper plug around the plutonium core, highlighting its high value and the precision required in its installation.

💡Trinity Test

The Trinity Test was the first detonation of a nuclear weapon, conducted by the United States in 1945 as part of the Manhattan Project. The script describes the preparations for the test, the assembly of the device, and the test's outcome, which validated the atomic bomb's design and confirmed its devastating power.

💡Atmospheric Ignition

Atmospheric ignition refers to the hypothetical scenario where a nuclear explosion could cause a self-sustaining reaction in the Earth's atmosphere, potentially leading to global destruction. The script discusses the concerns and calculations related to this possibility, emphasizing the scientific uncertainty and the ethical considerations of nuclear testing.

💡Nixie Tubes

Nixie tubes are an early form of electronic display device used to show numerical information. The script mentions them as a period-appropriate detail in the depiction of the Trinity Test, illustrating the technology of the time and the precision with which the test was documented.

💡Mach Stem

A mach stem is a feature of a blast wave from an airburst, where the wave reflects off the ground and adds to the forward-moving wave, increasing the blast pressure. The script describes how the data from the Trinity Test was used to understand and maximize the destructive potential of the atomic bomb when detonated above ground level.

💡Manhattan Project

The Manhattan Project was the U.S. research and development project during World War II that produced the first nuclear weapons. The script provides insights into the scale of the project, its resource consumption, and its output, which was a limited amount of fissile material for the atomic bombs.

Highlights

Assembly of the atomic bomb's 'gadget' based on declassified images.

Description of the plutonium sphere and its assembly with explosive lenses.

The necessity of symmetrical compression of the plutonium for the bomb to function.

Use of detonators to initiate a shockwave for the implosion process.

Inclusion of polonium and beryllium to emit neutrons and start the atomic reaction.

Historical footage and its replication in the movie 'Oppenheimer'.

Importance of a controlled environment for the final assembly of the bomb.

The delicate operation and high value of the tamper plug in the bomb assembly.

Radioactive heat and handling of the plutonium core.

The challenge of fitting the plutonium core due to temperature differences.

The stressful responsibility of the person setting up the bomb at the test site.

Concerns of atmospheric ignition and the potential global consequences.

Calculations and reassurances regarding the improbability of atmospheric ignition.

The timing and coordination required for the electrical detonation of the bomb.

Description of the Trinity test's visual documentation and its intensity.

The psychological impact of the bomb's detonation and its brightness.

The paradox of Oppenheimer's role in creating peace through warfare.

The scale of the Manhattan Project and its resources.

Reflection on the moral implications and legacy of the atomic bomb.

Transcripts

[bomb exploding]

- I'm a historian of nuclear weapons.

[bomb exploding]

And today I'm here to talk about the science

behind Oppenheimer.

[upbeat music]

So that's a scene of them assembling the gadget.

This is clearly based on some pictures that have come out,

and they're not a ton of pictures

showing this level of assembly

that have been declassified and released.

All the pictures we have of this are black and white.

The people who actually saw it described it

as being a sort of peach colored, a sort of tan colored.

Each of those wedges are several layers of high explosive.

So there are sort of variants of TNT

called explosive lenses, and they are putting them

around the plutonium sphere that powers the whole thing.

This is about the size of a grapefruit

So plutonium's solid metal.

Imagine you had a piece of steel and I said,

push it on all sides to make it smaller.

You need to shrink it by half its size

exactly symmetrically.

Each of these are the detonators.

When they all go off,

they're gonna start a shockwave through this device.

It's gonna start going in, in, in.

Inside that little sphere of plutonium

is an even tinier sphere of polonium and beryllium.

This thing, if you compress it, will shoot out some neutrons

that's meant to just start the reaction.

You push the whole thing together

and make an atomic bomb explode.

This is called implosion.

One of the things we see in the movie

is the final assembly of the gadget.

This is based on actual footage that was taken at the time.

Even the lighting looks like

in the historic footage that we have.

This is a hundred foot tower.

They have brought the explosive sphere

out to the test site by the tower

and they put a big tent around it.

You need this thing to be as controlled as possible.

If you got a pebble in there, it could deform the shock wave

by just enough to make the whole thing either not work

or not work very well.

So they want this to be a very pristine sort of environment,

which is hard to do when you're in the middle of the desert.

They're putting in in this scene

what's called the tamper plug.

The goal is to have this sit right around the plutonium core

in the middle of the bomb.

This is a delicate operation.

This tamper plug arguably is worth $400 million

in 1945 money.

They don't wanna mess this up,

because once you put the plutonium in there,

every little step of getting it closer to being a bomb

makes it a little bit more dangerous to be around

and radioactively, you know, problematic.

This core is like on the edge of being explosive.

It's also radioactive, it's also hot.

Plutonium in that quantity is so radioactive

that it's about 80 degrees Fahrenheit.

They're dropping it through the center of the bomb.

They've made a sort of trap door basically

into the bomb so that the lens on top can come out.

You can drop this thing in.

In real life, they went to put it in and it didn't fit.

Oh my God, have we totally messed this up?

Wait a minute, wait a minute.

It had to be the right temperature for it to fit.

The outer part was cooler than the inner part was,

and so they had to wait for them

to reach the same temperature,

and then it just slid into place.

So there had to be one person left in the tower

to set it all up at the very end, stay with the bomb,

do the final connections, and then head back.

And this was, of course, a very stressful job.

They had previous mock-ups

that were set off by lightning in the distance,

so they were in a very precarious state here.

There's a scene before the actual Trinity test

where General Groves is asking Oppenheimer

about the possibility of this test destroying the world.

- [Groves] There's a chance that when we push that button,

we destroy the world?

- One of the real concerns was this problem

of what they called atmospheric ignition.

What if the nitrogen and oxygen in the atmosphere

fuse together and release energy?

Could they release enough energy

that that would trigger more nuclear fusion

that then goes over the entire globe

and leaves at a burnt horrible cinder?

Turns out that kind of equation is really hard to do,

but let's imagine that it's like 100 times easier

than we think it is.

We can sort of make very conservative extrapolations

and we find it's probably not gonna happen.

- Chances are near zero.

- Near zero.

- What do you want from theory alone?

- Oppenheimer is giving the correct scientist's answer.

They basically concluded

it would be less than one in 3 million, something like that.

In the 1970s, weapon scientists redid those calculations.

Could you set the earth on fire if you wanted to?

Yes, but you need bombs

that would be hundreds of thousands of times

more explosive than any bombs we ever made.

And you'd need to have a much higher proportion

of the ocean be made out of a rare isotope called deuterium,

a different type of hydrogen.

If you had this, you could indeed turn the earth into a sun.

The detonation took place very late at night.

They wanted to see exactly how bright it was,

and it's gonna be harder to see that in the daytime

when you're competing with the actual sun.

They actually had recommended

that the bombs be dropped on Japan at night

because they would be more psychologically stunning.

But for logistical reasons,

they were dropped in the morning on both of the cities.

So those numbers you see are nixie tubes.

Those are a pre-digital way to display numbers.

It's a very nice period-appropriate touch.

So at this point, the gadget, as they called it,

is fully assembled.

You can tell that because the wires are sticking out the top

on the front, that's called the X Unit,

that's the firing unit, it's assembled.

To set off this kind of bomb,

you have to send a high voltage electrical signal

to 32 separate places at exactly the same time.

Nanosecond tolerances on the timing to have it work right.

And then they have a wire

going all the way back to base camp.

And if you hit the big button on the wire.

- Detonator charged.

- [Alex] You're telling the bomb,

go ahead and explode, and it will.

[nuke exploding]

In the movie Oppenheimer,

the Trinity test is one of the climax moments.

It's ridiculously bright,

much, much brighter than the actual sun.

What Oppenheimer's putting on here are welding goggles,

and these are so dark

that you really can't see anything in them

except something that is as bright as the sun.

There were a few people at the Trinity Test

who'd looked at the explosion

without anything over their eyes.

One of them, by accident, he dropped his goggles,

and one of them on purpose.

They both suffered from what was called flash blindness,

temporary blindness.

You'll see a big dark spot

over your vision for quite some time.

There were people who were relatively close,

thousands of yards.

Oppenheimer in the sort of control bunker,

much closer than a lot of the outlying ones.

Most of the people that were instructed to lay down

away from the blast so that they don't turn around

and either get knocked over or get a face full of dust.

So the Trinity test was heavily, heavily documented

both by pressure gauges and cameras

with telephoto lenses from a very far distance,

but some of them were closer in bunkers.

Anytime you see a closeup

and it's sort of like a wall of fire,

there are shots from the actual Trinity test

that looked pretty similar to that.

Interestingly, on some of the very earliest shots

where they were trying to get

the very first moments of the fireball,

it was hot enough that it burned holes in the film.

This particular shot is interesting

because this is what they call in the business a rope trick.

And they only show up when you can take pictures

that are 1,000 frames per second or something like this.

You have a tower with a bomb on it

and it's got wires stabilizing the tower,

and there's a little tendril of the fireball

that's going faster than the rest

because it's blowing up the wire as it goes down there.

No one at Trinity could have actually seen this.

What you're seeing here is the complex interaction

that happens when the blast wave hits the ground,

goes straight down, bounces back up,

and then intersects with that blast wave coming out.

There's a really big difference

in how the blast wave behaves

from a bomb that's right on the ground

from one that's a little bit in the air.

They want this, what's called the mach stem,

to have a wide area of destruction.

That's how you maximize the blast pressure,

detonating very high above the ground.

They're gonna use that data

to set the altitude of the atomic bomb over Japan.

When they went into the Trinity test,

their sort of best guess

was it would maybe be 4,000 tons of TNT.

It ended up being more powerful than they thought

by a factor of like 5, 20,000 tons of TNT equivalent.

This is enough to destroy a sort of medium-sized city.

If you're a much bigger city, like say New York City,

it's enough to destroy like Midtown.

So this is one of the reasons why Trinity is so important.

It's not just it works.

They find out it works really well.

So the Manhattan Project is this gigantic endeavor.

It's this massive industrial project

and employs like 500,000 people.

It's like 1% of the civilian labor force,

and it cost like $2 billion in their money,

which is like 1% of the whole cost of World War II.

They use 1% of all the electricity in the country

to make these weapons.

They're building an industry in like two and a half years,

and the output of that industry

is a very tiny amount of material.

A 6 kilogram plutonium core, 13.5 pounds,

that's the one they first test at Trinity.

About 64 kilograms, so about 120 something pounds

of highly enriched uranium, uranium 235,

that's for the bomb that's gonna be dropped on Hiroshima.

And then they have one more plutonium core.

That's the one they're gonna end up dropping on Nagasaki.

So all of that effort

is to make these three cores for the bombs.

And they had one more bomb in the pipeline.

They ended up never sending it, the war ended.

Many of these people talked about this

as the best years of their life in some ways.

They had a lot of fun,

and some of them felt quite guilty about that

after Hiroshima and Nagasaki.

Oppenheimer's a really complicated character.

What he said he regretted was that after World War II,

they continued to make more weapons

and they continued to make bigger weapons

and they continued to make the kind of world

that he thought would ultimately put

civilization itself in danger.

- In the years to come,

it will be possible to kill 40 million American people

by the use of atomic bombs in a single night.

- [Alex] He knew in 1945 that there were ideas on the table

for bombs that would be thousands of times more powerful,

and that the nations of the world

could all get them if they wanted them,

and that a war with bombs of that big

could be fatal for the entire species.

And so that's the sort of paradox of Oppenheimer,

this person who wants peace, but he does it through war.