Why Oppenheimer Deserves His Own Movie

Aug 10, 2023

Why Oppenheimer Deserves His Own Movie

J. Robert Oppenheimer forever changed the course of history. He may be the most important physicist to have ever lived. Part of this video is sponsored by Wren. Offset your carbon footprint on Wren: https://www.wren.co/start/veritasium1 For the first 100 people who sign up, I will personally pay for the first month of your subscription!

If you want to learn more about Oppeheimer, I strongly recommend the book “American Prometheus” By Kai Bird and Martin Sherwin. It is a remarkable book, very much deserving of the Pulitzer prize it received.

If you’re looking for a molecular modeling kit, try Snatoms – a kit I invented where the atoms snap together magnetically – https://ve42.co/SnatomsV

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A huge thank you to Dr. Martin Rohde and Dr. Antonia Denkova from the TU Delft for proofreading the script and providing valuable feedback.

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References:

Bird, K., \u0026 Sherwin, M. J. (2021). American Prometheus: the triumph and tragedy of J. Robert Oppenheimer. Atlantic Books.

Smith, A. K., \u0026 Weiner, C. (1980). Robert Oppenheimer: letters and recollections. Bulletin of the Atomic Scientists, 36(5), 19-27. - https://ve42.co/Smith1980

Combes, J. M., Duclos, P., \u0026 Seiler, R. (1981). The born-oppenheimer approximation. Rigorous atomic and molecular physics, 185-213. - https://ve42.co/Combes1981

Rhodes, R. (2012). The making of the atomic bomb. Simon and Schuster.

Oppenheimer, J. R., \u0026 Volkoff, G. M. (1939). On massive neutron cores. Physical Review, 55(4), 374. - https://ve42.co/Oppenheimer1939b

Oppenheimer, J. R. (1927). Bemerkung zur Zerstreuung der α-Teilchen. Zeitschrift für Physik, 43(5-6), 413-415. - https://ve42.co/Oppenheimer1927

Oppenheimer, J. R. (1927). Zur quantenmechanik der richtungsentartung. Zeitschrift für Physik, 43(1-2), 27-46. - https://ve42.co/Oppenheimer1927b

Born, M., \u0026 Oppenheimer, R. (1927). Zur Quantentheorie der Molekeln Annalen der Physik, v. 84. - https://ve42.co/Born1927

Oppenheimer, J. R. (1928). Three notes on the quantum theory of aperiodic effects. Physical review, 31(1), 66.

Oppenheimer, J. R. (1928). On the quantum theory of the capture of electrons. Physical review, 31(3), 349.

Oppenheimer, J. R. (1931). Note on light quanta and the electromagnetic field. Physical Review, 38(4), 725.

Furry, W. H., \u0026 Oppenheimer, J. R. (1934). On the theory of the electron and positive. Physical Review, 45(4), 245. - https://ve42.co/Oppenheimer1934

Oppenheimer, J. R. (1935). Note on charge and field fluctuations. Physical Review, 47(2), 144. - https://ve42.co/Oppenheimer1935

Oppenheimer, J. R., \u0026 Snyder, H. (1939). On continued gravitational contraction. Physical Review, 56(5), 455. - https://ve42.co/Oppenheimer1939

Oppenheimer, J. R., \u0026 Phillips, M. (1935). Note on the transmutation function for deuterons. Physical Review, 48(6), 500. - https://ve42.co/Oppenheimer1935b

Malik, J. (1985). Yields of the Hiroshima and Nagasaki nuclear explosions (No. LA-8819). Los Alamos National Lab.(LANL), Los Alamos, NM (United States). - https://ve42.co/Malik1985

Ignition of the atmosphere with nuclear bombs — https://ve42.co/Konopinski46

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Written by Petr Lebedev \u0026 Derek Muller
Edited by Trenton Oliver \u0026 Katrina Jackson
Filmed by Derek Muller
Animation by Fabio Albertelli, Ivy Tello, \u0026 Mike Radjabov
Illustration by Jakub Misiek and Celia Bode
Additional video/photos supplied by Getty Images \u0026 Pond5
Music from Epidemic Sound

Content

0.24 -> J. Robert Oppenheimer

1.56 -> might be the most important physicist

3.84 -> to have ever lived.

5.4 -> He never won a Nobel Prize,

7.26 -> but he changed the world more than most Nobel Prize winners.

11.46 -> Under his leadership,

12.63 -> the best physicists of the 20th century

15.36 -> built the atomic bomb

17.4 -> forever changing the course of history.

20.22 -> - If there is another world war,

22.86 -> this civilization may go under.

26.43 -> - [Derek] He has affected every war waged

28.86 -> and every peace settled since the end of World War ii.

32.167 -> He also created a way for humanity to destroy itself.

37.08 -> - Now I am become death,

39.51 -> the destroyer of worlds.

42 -> - [Derek] This video is about how to build an atomic bomb,

45.06 -> the life of Oppenheimer,

46.8 -> and why serious scientists were worried about the explosion

50.4 -> setting fire to the atmosphere,

52.8 -> ending all life on earth.

56.52 -> Part of this video is brought to you by Wren.

61.65 -> When J. Robert Oppenheimer was 21,

64.26 -> he placed an apple laced with toxic chemicals

67.32 -> on the desk of his physics tutor.

69.179 -> The tutor, Patrick Blackett,

71.25 -> was an experimentalist and he had hounded Robert

74.07 -> to do more of what he thought

75.54 -> Robert wasn't very good at, experimental work.

78.584 -> Oppenheimer had already been spending his days in a corner

81.81 -> of JJ Thompson's basement laboratory,

84.06 -> attempting to make thin films of beryllium,

86.46 -> which were used to study electrons.

88.95 -> But Oppenheimer was clumsy and not good at this work.

93.87 -> He was soon avoiding his duties in the lab,

96.24 -> spending his time listening to lectures

98.1 -> and reading physics journals.

99.9 -> It was 1925 and the 21 year old Oppenheimer was becoming

103.68 -> fascinated by the new field of quantum mechanics.

107.52 -> Despite being surrounded by brilliant physicists

110.55 -> like Rutherford and Chadwick,

112.74 -> Oppenheimer was deeply unhappy.

115.38 -> He wrote, "I'm having a pretty bad time.

118.11 -> The lab work is a terrible bore,

120.06 -> and I'm so bad at it that it's impossible to feel

123.09 -> that I'm learning anything."

124.518 -> A friend walked in on him,

126.06 -> lying on the floor of his room,

127.5 -> which he called "A miserable hole",

130.08 -> groaning and rolling from side to side in emotional anguish.

133.925 -> It was in this state that Robert

136.62 -> attempted to poison Blackett.

139.08 -> The specifics are lost to history.

141.15 -> There are conflicting reports if Oppenheimer used cyanide

143.957 -> or something he found in the lab,

146.01 -> which would've just made Blackett sick.

148.59 -> This story sounds unbelievable,

150.525 -> but Oppenheimer himself confirmed it.

153.597 -> Luckily, Blackett did not eat the apple,

156.524 -> but the attempted poisoning became known

159 -> to the Cambridge University authorities.

161.79 -> Robert's parents were visiting their son

163.44 -> from the US at the time,

164.61 -> and Julius Oppenheimer successfully lobbied Cambridge

168.03 -> not to press criminal charges. Due to his family's wealth,

171.63 -> Robert wasn't even expelled from Cambridge

173.97 -> on the condition that he had periodic counseling sessions

176.499 -> with a psychiatrist in London.

179.207 -> (train horn blaring)

181.26 -> In the summer of 1926,

182.64 -> Robert traveled to the University of Göttingen.

185.7 -> The chairman of the department was Max Born,

188.13 -> who just two years earlier had coined the term,

191.269 -> "Quantum Mechanics".

193.26 -> Born was reportedly a thoughtful and gentle teacher

196.44 -> and had nurtured the work of Werner Heisenberg,

198.93 -> Wolfgang Pauli, Enrico Fermi,

201.03 -> and Eugene Wigner,

202.29 -> basically the who's who of quantum mechanics.

204.678 -> The class that Oppenheimer was in was also extraordinary,

208.14 -> including luminaries like Paul Dirac and John Von Neumann,

212.22 -> where the academic culture at Cambridge focused on

214.13 -> experimental physics.

216.09 -> Göttingen was all about theoretical physics,

218.7 -> and under Max Born's mentorship,

221.04 -> Oppenheimer thrived.

222.66 -> His mental health improved,

224.28 -> and he found a community of people who were

226.32 -> as obsessed with physics as he was.

229.98 -> On November 14th, 1926,

232.2 -> Robert wrote to Frank, his younger brother,

234.596 -> "You would like Göttingen.

236.52 -> I find the work hard, thank God,

238.62 -> and almost pleasant."

240.69 -> Robert was thriving and his talent was being recognized.

244.29 -> Born later wrote,

245.257 -> "He was a man of great talent and he was conscious

248.25 -> of his superiority in a way which was embarrassing

251.19 -> and led to trouble."

253.2 -> When Oppenheimer was 23,

254.88 -> he graduated with his PhD in physics.

257.43 -> He wrote his thesis in German on the quantum theory

260.55 -> of continuous spectra.

262.171 -> All in all,

263.07 -> he published more than a dozen papers

264.585 -> in the two years he was at Göttingen.

266.883 -> Many of them expanded upon the work of Werner Heisenberg,

270.57 -> who was just three years older than Oppenheimer.

273.001 -> The two eventually met in 1927,

276.24 -> the same year Heisenberg published his groundbreaking paper

279.48 -> on the Quantum uncertainty principle.

281.486 -> By all accounts,

282.84 -> the pair got along well.

284.83 -> There was no way to know that just 15 years later,

287.73 -> they would be deadly rivals attempting to build

290.85 -> the first nuclear bomb.

292.35 -> Oppenheimer for the USA

294.24 -> and Heisenberg for Nazi Germany.

297.226 -> At the time,

298.35 -> it was thought that getting significant amounts of energy

301.35 -> out of radioactive atoms was impossible.

304.95 -> Ever since the discovery of radioactivity

307.23 -> by Henri Becquerel, Marie Curie,

309 -> and Pierre Curie in the late 1890s,

311.55 -> it was known that radioactivity was a passive process.

315.21 -> Unstable atoms would just decay at random,

317.46 -> unpredictable times,

319.65 -> and surely there was no way to control that.

323.2 -> In 1933, Ernest Rutherford,

326.07 -> Oppenheimer's old boss from Cambridge wrote that,

328.927 -> "Anyone who expects a source of power

330.75 -> from the transformations of these atoms

332.58 -> is talking moonshine."

334.29 -> That same year,

335.25 -> Albert Einstein said,

336.277 -> "That there is not the slightest indication

338.195 -> that nuclear energy will ever be obtainable.

340.729 -> It would mean that the atom

342.48 -> would have to be shattered at will."

346.26 -> So how would you break an atomic nucleus?

349.183 -> Well, you could take a proton

351.24 -> and accelerate it through a large electric field

353.73 -> and then smash it into a nucleus.

356.58 -> This is exactly what John Cockcroft

358.617 -> and Ernest Walton did in 1932.

360.93 -> They accelerated protons into lithium nuclei,

364.56 -> breaking them apart.

365.526 -> The pair would later win a Nobel Prize for this work,

368.982 -> but a proton is positively charged,

371.79 -> so it's repelled by all nuclei,

374.22 -> which are also positively charged.

376.65 -> So to give them a hope of overcoming this barrier,

379.35 -> Cockcroft and Walton had to use 250,000 volts

383.61 -> to accelerate the protons.

385.44 -> Even then, only about one in a billion protons

388.71 -> actually hit and split a lithium nucleus,

391.92 -> so this would not be an effective way to get energy.

396.24 -> But there is another way.

399.66 -> In 1932, the neutron was discovered

402.72 -> this subatomic particle that's about 0.1%

406.11 -> heavier than a proton,

407.64 -> and it has no electric charge,

409.468 -> so a neutron would not be repelled from a nucleus.

413.76 -> And in 1933,

415.41 -> Leo Szilard was thinking about how you could use neutrons

418.95 -> to split nuclei.

420.757 -> "It suddenly occurred to me that if we could find an element

423.81 -> which is split by neutrons and which would emit two neutrons

427.35 -> when it absorbed one neutron,

429.12 -> such an element if assembled sufficiently large mass,

432.307 -> could sustain a nuclear chain reaction."

436.11 -> But the thing is,

437.19 -> nobody knew if there was an element

439.38 -> that had a kind of nucleus that would do that.

444.06 -> On the 29th of January, 1939,

446.55 -> Louise Alvarez, a promising young physicist,

448.95 -> was getting a haircut while reading

450.547 -> "The San Francisco Chronicle",

452.123 -> and suddenly he got outta the chair

454.53 -> halfway through the haircut and ran to Oppenheimer's office.

458.43 -> Alvarez read an article about how two German chemists,

461.43 -> Otto Hahn and Fritz Strassmann

463.44 -> had successfully split an atom of uranium

466.02 -> by bombarding it with neutrons.

468.326 -> Oppenheimer was not impressed.

470.977 -> "That's impossible."

472.11 -> He reportedly told the Young Alvarez

474.27 -> proceeding to mathematically prove on his blackboard

476.82 -> why fission could never be achieved.

480.84 -> But the next day,

482.1 -> Alvarez had repeated the experiment

484.47 -> and invited Oppenheimer to see it.

486.704 -> Alvarez later recalled that,

488.437 -> "In less than 15 minutes,

489.887 -> he not only agreed that the reaction was authentic,

492.96 -> but also speculated that in the process,

494.978 -> extra neutrons would boil off.

497.28 -> That could be used to split more uranium atoms

499.71 -> and thereby generate power or make bombs."

503.292 -> When a single atom of uranium-235 splits apart,

507.18 -> it loses a little bit of mass,

509.13 -> which is released as energy.

511.02 -> Following Einstein's mass energy equivalence.

513.99 -> That is a tiny amount of energy,

516.48 -> about 20 times less than the amount required

519.33 -> to raise a grain of sand,

520.92 -> the thickness of a piece of paper.

523.53 -> But atoms are also tiny.

525.51 -> In a one kilogram lump of uranium,

527.55 -> there are about a trillion, trillion atoms,

530.73 -> so the energy quickly adds up.

533.61 -> Soon, almost everyone was convinced in August of 1939,

537.93 -> Einstein, who just six years earlier

540.03 -> believed that nuclear bombs were impossible,

542.22 -> signed his name to a letter

543.78 -> addressed to President Franklin Roosevelt.

545.843 -> The letter actually written by Szilard warned Roosevelt

549.51 -> of the possibility of nuclear weapons.

551.79 -> It also pointed out that Germany had access to uranium

554.4 -> from the mines in Czechoslovakia,

556.47 -> which was recently taken over by the Nazis.

559.53 -> Roosevelt began an informal uranium committee

562.65 -> to discuss this topic,

564.39 -> but then for two years, nothing happened.

568.68 -> In 1941, Roosevelt upgraded the informal

571.86 -> uranium committee to the S-1 committee,

574.41 -> which would report directly to the White House.

577.05 -> The explicit goal was to develop an atomic bomb,

580.592 -> and in May, 1942,

582.507 -> Oppenheimer was hired onto the committee

585.15 -> to be the coordinator of rapid rupture.

588.724 -> So why was he selected?

591.682 -> (dramatic music)

594.72 -> Well, after completing his PhD,

596.234 -> Oppenheimer became a physics professor,

598.89 -> first at UC Berkeley, and then at Caltech,

601.276 -> the brilliance he had shown

603.06 -> under Max Born's tutelage didn't fade.

605.64 -> Indeed, it blossomed into a remarkable

607.559 -> but strange physics career.

610.74 -> In the 15 years after finishing his PhD,

613.53 -> Oppenheimer made important contributions to everything from

616.23 -> nuclear physics to quantum field theory,

618.75 -> and even astrophysics.

620.52 -> He had a number of Nobel Prize winning ideas.

622.72 -> One of his students, Willis Lamb,

624.54 -> became a Nobel laureate,

626.43 -> but Oppenheimer himself was nominated three times,

629.003 -> but never actually won the Nobel Prize.

633.42 -> When asked why he thought that Oppenheimer

635.4 -> never won the Nobel Prize,

636.906 -> Murray Gell-Mann said that,

638.917 -> "He didn't have Sitzfleisch"

641.16 -> A German word that translates to sitting flesh.

644.34 -> The ability to sit down in a chair for a long time

647.4 -> and do the hard work.

648.727 -> "He never wrote a long paper or did a long calculation.

652.59 -> He didn't have the patience for that."

654.713 -> Wolfgang Pauli also said,

656.416 -> "His ideas are very good,

658.47 -> but his calculations are always wrong."

663.6 -> But Oppenheimer was amazing with people.

666.66 -> He was a natural and charismatic leader,

669.03 -> and this combination,

670.32 -> his charisma and his ability to generate great ideas

673.214 -> would serve him well in the next phase of his life.

676.297 -> (upbeat music)

681.51 -> On the 18th of September, 1942,

683.73 -> general Leslie Groves was put in charge

686.07 -> of the Manhattan Project.

687.69 -> - I was responsible for the development of the atomic bomb.

691.92 -> - [Derek] On day one, he ordered 1200 tons of uranium ore.

696.011 -> The next day,

697.23 -> he ordered to buy the Oak Ridge site

699.27 -> where the ore would be refined.

701.43 -> The next month in a surprising move,

703.17 -> he chose Oppenheimer to be the science director

705.75 -> of the soon to be established Los Alamos laboratory.

709.47 -> Oppenheimer had just been selected to be the chief architect

712.35 -> of the atomic bomb.

715.83 -> The military establishment had concerns.

718.385 -> Oppenheimer did not have a Nobel Prize,

721.08 -> so would the scientists hired for the project,

723.18 -> respect his opinion,

724.29 -> and follow his leadership?

726.12 -> Oppenheimer also had no prior administrative experience

729.09 -> over a large project like this.

731.55 -> Furthermore, he was a theoretical physicist,

734.19 -> who according to Isidor Rabi,

736.237 -> "Was a very impractical fellow.

738.66 -> He didn't know anything about equipment."

741.45 -> And then there was the problem

742.8 -> of Oppenheimer's political stance.

744.72 -> He had links to the Communist Party,

746.97 -> including his wife, Catherine,

748.77 -> who was a member of that party.

751.56 -> But Groves was impressed by Oppenheimer.

754.17 -> He valued his overwhelming ambition.

756.75 -> He also knew that Oppenheimer's ability to understand

759 -> problems not just in physics,

760.53 -> but chemistry, engineering,

761.97 -> and metallurgy would be invaluable.

764.58 -> Groves thought that Oppenheimer was a "Real genius."

768.27 -> Saying that why Oppenheimer knows about everything.

771.877 -> "He can talk to you about anything you bring up.

774 -> Well, not exactly.

775.05 -> He doesn't know anything about sports."

777.9 -> The two men couldn't have been more different.

780.27 -> Oppenheimer weighed half as much as Groves

782.88 -> despite both of them being nearly six feet tall.

785.647 -> Ideologically, Oppenheimer was a communist.

788.82 -> Groves, a staunch conservative,

791.16 -> but Groves was convinced that Oppenheimer

793.26 -> would be the person that would build the atomic bomb

795.6 -> before the Nazis,

796.86 -> and that was all that mattered.

799.263 -> Isador Rabi later commented that,

801.12 -> hiring Oppenheimer for this role was

804.402 -> "A real stroke of genius

805.235 -> on the part of General Groves,

806.19 -> who was not generally considered to be a genius."

809.7 -> The Manhattan Project needed a location.

812.61 -> Somewhere isolated to keep the project secret

814.927 -> safe from enemy attack.

816.845 -> And while no one wanted to admit it,

818.91 -> somewhere that was sparsely populated,

820.83 -> just in case there was an accident,

824.31 -> Oppenheimer proposed Los Alamos, New Mexico.

827.31 -> He had fallen in love with the harsh desert in the mountains

829.89 -> of New Mexico when he was in his twenties.

831.758 -> In 1929, Oppenheimer wrote to a friend.

834.42 -> "My two great loves are physics and New Mexico.

837.9 -> It's a pity they can't be combined."

840.6 -> But Oppenheimer had severely underestimated the logistical

843.48 -> challenge ahead.

844.648 -> (gentle music)

847.779 -> In 1943, Oppenheimer estimated

850.44 -> that he'd need about six scientists

853.118 -> supported by a handful of engineers

855.3 -> and technicians to make a bomb.

860.22 -> He was off by two orders of magnitude.

864.06 -> 764 scientists would end up

866.16 -> working for the Manhattan Project.

867.81 -> 302 of which would work at the Los Alamos site.

873.27 -> Over 600,000 people in total were involved

876.87 -> with the making of the atomic bomb.

880.11 -> By this point, making the atom bomb didn't seem impossible.

883.44 -> It seemed likely.

887.76 -> On the 2nd of December, 1942,

889.89 -> a team of physicists at the University of Chicago

892.35 -> led by Enrico Fermi created the world's

895.23 -> first artificial nuclear reactor Pile-1.

898.68 -> It consisted of 45 tons of uranium and uranium oxide

902.58 -> and 330 tons of graphite blocks.

905.425 -> Horrifyingly enough.

906.87 -> It was located under the stands of the football field.

910.74 -> It generated about half a watt of power,

914.82 -> and if you can make a nuclear power plant,

916.785 -> you can make a bomb.

918.63 -> The only real difference between the two

920.46 -> is how many neutrons hit the next atom,

922.5 -> causing it to split and release more neutrons.

925.59 -> If on average that number is one,

927.69 -> there will be a stable self-sustaining chain reaction,

930.57 -> but it won't grow.

931.648 -> If it's less than one,

933.39 -> the reaction will die down,

935.34 -> and if it's more than one,

936.45 -> the reaction will grow.

937.997 -> This is known as the multiplication factor, K.

942.09 -> Nuclear reactions are similar to pandemics in this way.

948.21 -> The simplest way to make a nuclear bomb

950.25 -> is to get enough fissile material close together

953.31 -> that it creates a runaway chain reaction.

955.98 -> That amount is known as the critical mass.

958.77 -> With uranium-235,

960.12 -> you need about 52 kilograms.

962.7 -> Forming a sphere with a diameter of 17 centimeters.

966.23 -> If you use plutonium-239,

968.7 -> the critical mass is much smaller,

970.26 -> only around 10 kilograms,

972.12 -> which would create a sphere only 10 centimeters wide.

976.17 -> For the first few years,

977.37 -> the scientists worked on a bomb with a gun type design.

980.79 -> Inside a gun type bomb,

982.59 -> you have two slabs of uranium-235,

984.8 -> both of which are below the critical mass.

987.72 -> Then using a conventional explosive like cordite,

991.32 -> you rapidly fire one towards the other.

994.62 -> So the combined mass is higher than the critical mass.

998.43 -> When the uranium bullet is about 25 centimeters away,

1001.85 -> the nuclear chain reaction begins

1004.28 -> resulting in an atomic explosion.

1007.61 -> Despite the simple design,

1009.29 -> it is not very efficient.

1011.18 -> Only a small percentage of the uranium undergoes fission,

1013.818 -> so the total yield of the bomb is much smaller.

1017.21 -> You also run into some unexpected problems,

1020.09 -> like how do you make sure the uranium

1021.92 -> slides smoothly through the barrel?

1024.185 -> Well, you use oil to lubricate the barrel,

1028.19 -> but all the synthetic oils the scientists tried

1030.65 -> would dry up.

1032.12 -> In the end,

1032.96 -> the only oil they could find that would work

1035.72 -> was the oil from sperm whales.

1040.4 -> Only about 0.7% of naturally occurring uranium is U235,

1045.62 -> the fissile fuel for nuclear bombs.

1048.44 -> When U235 absorbs a neutron,

1051.05 -> it briefly becomes U236,

1053.54 -> and then it rips itself roughly in half

1056.3 -> and releases on average 2.4 neutrons per fission.

1060.56 -> But when you get uranium outta the ground,

1062.48 -> most of it is U238,

1064.49 -> which doesn't undergo fission.

1066.83 -> So to make a nuclear bomb,

1068.06 -> the scientists use gigantic mass spectrometers

1071.028 -> to separate out and concentrate the U235,

1075.2 -> and the resulting substance was uranium

1077.96 -> with a much higher concentration of U235.

1081.29 -> In other words, it was enriched.

1084.32 -> There was another option though.

1086.81 -> In early 1941,

1088.49 -> a new element was discovered or rather synthesized.

1092.18 -> When a neutron is absorbed by a nucleus of uranium-238,

1095.57 -> it turns into uranium-239.

1098.257 -> U239 is unstable,

1100.58 -> so it decays into Neptunium,

1102.62 -> which then becomes plutonium.

1105.71 -> There are three things that matter for this story.

1108.23 -> First is that plutonium-239

1110.022 -> is a great fuel for a nuclear bomb.

1112.43 -> It has a critical mass of only about 10 kilograms.

1115.49 -> Second, it is cheaper to make than to separate uranium-235

1119.492 -> and third, it reacts too quickly

1122.06 -> to be used in a gun type device.

1124.04 -> It would fizzle,

1124.873 -> meaning only a tiny fraction of the fuel

1126.95 -> would undergo fission.

1129.05 -> But there is a way to make a bomb using plutonium.

1131.831 -> Critical mass changes depending on the density

1134.78 -> of the material.

1136.1 -> Under normal pressure conditions,

1137.745 -> six kilograms of plutonium-239 won't explode.

1142.01 -> But if you compress it,

1143.99 -> the atoms get closer together and the chance of a stay

1147.2 -> neutron hitting the nucleus increases.

1149.84 -> So the higher the density, the lower the critical mass.

1153.662 -> So if you set off conventional explosives

1156.8 -> around a ball of plutonium,

1158.81 -> you can get it compressed enough

1160.34 -> to start a nuclear chain reaction.

1162.763 -> And this was the whole idea behind

1165.047 -> the implosion bomb design.

1169.73 -> There are a couple ways to cheat lowering the critical mass.

1173.18 -> For one thing,

1174.05 -> you surround the sphere with a material that reflects

1176.39 -> neutrons decreasing the amount of nuclear fuel

1178.85 -> you need to start a chain reaction.

1181.04 -> You can also have a neutron source,

1183.26 -> something that kick starts the chain reaction.

1185.601 -> For the first implosion bomb,

1188.24 -> scientists created a device called the urchin,

1190.97 -> which was a tiny pellet weighing just seven grams,

1194.66 -> and it would sit at the heart of the bomb.

1197.24 -> It was made of beryllium and polonium

1199.94 -> separated by a layer of nickel and gold.

1202.85 -> The idea was that when the explosives detonated,

1205.76 -> the shockwave would mix the beryllium and polonium together,

1209.33 -> and then the alpha particles from polonium

1211.55 -> would cause the beryllium to release a flood of neutrons,

1215.33 -> which would set off the nuclear chain reaction.

1219.38 -> At least that was the hope.

1221.15 -> An atomic bomb had never been made before.

1223.213 -> Oppenheimer and the rest of the scientists at Los Alamos

1226.46 -> needed to act quickly.

1227.99 -> It was already 1945,

1229.91 -> and Truman wanted to test the weapon

1232.13 -> before the start of the Potsdam conference.

1234.8 -> That's where Truman, Churchill,

1236.51 -> and Stalin would come together to plan the post-war piece.

1240.17 -> The conference began on the 17th of July.

1243.74 -> The earliest date that everything could be ready

1246.14 -> for the bomb was just one day earlier.

1249.2 -> So that is when the test was scheduled.

1252.56 -> It was Codenamed Trinity.

1257.78 -> The night before Oppenheimer was nervous.

1260.87 -> There were so many things that could go wrong.

1263.63 -> The last test firing of the explosives

1266.21 -> without the actual plutonium core was a failure.

1270.65 -> To calm himself,

1271.85 -> he recited a stanza from the Bhagavad Gita,

1274.79 -> the sacred Hindu poem.

1276.83 -> He had actually translated the Gita from the original

1279.44 -> Sanskrit in himself.

1281.338 -> In battle, in forest,

1283.67 -> at the precipice in the mountains,

1285.409 -> on the dark great sea,

1288.44 -> in the midst of javelins

1289.94 -> and arrows in sleep,

1291.95 -> in confusion, in the depths of shame,

1294.902 -> the good deeds a man has done before defend him.

1301.22 -> Perhaps more terrifying than the idea of the bomb

1303.77 -> not working was that it would work too well.

1310.34 -> Around 1942, Oppenheimer discussed with Arthur Compton

1314.313 -> a terrible possibility that a nuclear test

1318.23 -> could end the world.

1319.766 -> The worry was that the nuclear bomb

1322.01 -> would create temperatures so hot that fusion would occur.

1328.31 -> A tiny fraction of the atmosphere,

1330.26 -> just one part in 2 million is hydrogen gas.

1334.52 -> But the worry was that at high enough temperatures

1336.65 -> and pressures that hydrogen could fuse to together

1340.04 -> releasing energy,

1341.66 -> this energy would fuse more hydrogen.

1343.952 -> It could also break apart the hydrogen

1346.49 -> from water vapor causing that to fuse as well.

1350.12 -> That would release even more energy

1351.89 -> causing yet more fusion until the entirety

1355.25 -> of the Earth's atmosphere would become a giant fusion bomb.

1360.14 -> Recalling his conversations with Oppenheimer in 1959,

1363.68 -> Compton said, "Nor was this all that Oppenheimer feared.

1367.146 -> The nitrogen in the air is also unstable,

1370.52 -> though in less degree.

1371.975 -> Might not it, too, be set off by an

1374.93 -> atomic explosion in the atmosphere."

1377.69 -> Most of the scientists quickly realized

1379.64 -> how unlikely this scenario was,

1381.53 -> and they continued on with the project,

1383.63 -> so no one took the idea too seriously.

1386.39 -> But the thought of starting a fusion reaction with a fission

1389.81 -> weapon would become very important after the war.

1393.391 -> (dramatic music)

1397.13 -> The Trinity test was scheduled for 4:00 AM

1400.108 -> but it was delayed due to a storm.

1403.07 -> So at 5:29 and 21 seconds, the gadget,

1407.06 -> the world's first nuclear bomb detonated,

1410.63 -> the high explosive squeezed the core of plutonium inwards.

1414.504 -> The shockwave mixed the beryllium and polonium

1417.23 -> releasing a flood of neutrons.

1420.08 -> The urchin worked.

1421.76 -> It jump started the nuclear reaction,

1424.1 -> and now there was no way to stop it.

1427.58 -> Just six kilograms of plutonium created an explosion

1431.09 -> that was equivalent to nearly 25,000 tons of TNT.

1435.86 -> The New Mexico mountains were illuminated

1437.75 -> brighter than in daytime.

1439.373 -> The shockwave was felt from over 160 kilometers away.

1444.83 -> The mushroom cloud rose to 12 kilometers into the sky.

1449.27 -> It was so hot that the desert sand melted

1452.36 -> into a glassy mineral, now known as trinitite.

1455.867 -> Fortunately, the blast did not set fire to the atmosphere.

1464.21 -> On August 6th, 1945,

1465.89 -> the Boeing B29 Flying Fortress dropped little boy,

1469.97 -> a gun type nuclear bomb with 64 kilograms

1473.15 -> of enriched uranium.

1474.771 -> The nitro cellulose ignited pushing the slugs

1477.65 -> of uranium-235 together,

1479.72 -> tipping it over its critical mass.

1481.824 -> The blast from the explosion equivalent

1484.397 -> to 15,000 tons of TNT,

1488.06 -> killed nearly 70,000 people.

1491.66 -> Another 70,000 would die from burns and radiation poisoning

1495.89 -> in the following months.

1497.87 -> Three days later,

1498.8 -> an implosion type bomb, like the gadget,

1501.29 -> was dropped on Nagasaki

1502.266 -> killing an estimated 80,000 more people.

1507.23 -> More than 95% of the 225,000 people killed

1512.21 -> in the bombings of Hiroshima and Nagasaki were civilians.

1515.781 -> Most were women and children.

1521.09 -> In 1965, recalling the moments after the Trinity test,

1525.5 -> Oppenheimer said that he thought of another verse

1528.05 -> from the Ghita.

1529.52 -> - He knew the world would not be the same.

1534.557 -> Few people laughed,

1538.82 -> few people cried.

1541.01 -> Most people were silent.

1545.9 -> I remembered the line from the Hindu scripture,

1549.8 -> the (speaking foreign language).

1554.513 -> The Vishnu is trying to persuade the prince

1560.21 -> that he should do his duty

1563.917 -> and to impress him takes on his multi-armed form and says,

1572.453 -> 'Now I am become death the destroyer of worlds.'

1579.26 -> I suppose we all thought that one way or another.

1583.37 -> - [Derek] After the war,

1584.51 -> Oppenheimer was a national hero.

1586.94 -> His portrait was on the cover of Time Magazine,

1589.46 -> and he became a household name.

1592.67 -> In 1947, he became the director

1594.77 -> of the Institute of Advanced Study at Princeton.

1597.53 -> He also became the chairman

1599.06 -> of the General Advisory Committee,

1601.13 -> where he became an advisor on nuclear weapons

1603.47 -> related issues.

1605.03 -> He used his position to argue for arms control.

1610.1 -> (dramatic music)

1611.06 -> In August, 1949,

1612.77 -> the Soviet Union tested their first atomic weapon,

1620.16 -> and the US military quickly decided

1622.43 -> that the best course of action

1624.11 -> was to develop a more powerful bomb.

1626.87 -> The hydrogen bomb,

1628.43 -> known as "The Super",

1630.347 -> Oppenheimer was against the development

1633.38 -> of The Super on ethical grounds

1635.54 -> and the worry that it would start an arms race.

1638.84 -> But Truman's administration pushed through,

1641.48 -> and three years later, Ivy Mike,

1643.64 -> the first hydrogen bomb was tested in the Marshall Islands.

1647.57 -> It had a yield of 10.4 megatons of TNT.

1651.8 -> That's 400 times more powerful than the Trinity test.

1660.74 -> A hydrogen bomb is actually three bombs in one,

1664.25 -> a conventional bomb, a fission bomb,

1666.38 -> and a fusion bomb.

1668.12 -> The conventional explosives trigger a fission reaction,

1670.969 -> which increases the temperature and pressure

1673.43 -> enough to fuse deuterium and tritium together,

1676.85 -> releasing a huge amount of energy.

1680.3 -> In 1961, the Soviet Union tested the Tsar Bomba,

1684.35 -> the most powerful explosion ever detonated.

1687.65 -> It was another five times more powerful than Ivy Mike

1691.25 -> around 2000 times more powerful than Trinity.

1697.04 -> This kind of arms race

1697.873 -> was exactly what Oppenheimer had feared,

1701.42 -> in part, due to his opposition to the hydrogen bomb.

1703.76 -> And due to his calls to avert a nuclear arms race,

1706.64 -> Oppenheimer was essentially put on trial

1708.74 -> to revoke his security clearance.

1710.81 -> He had been surveilled while he was working

1712.67 -> for the Manhattan Project,

1713.99 -> but that surveillance didn't stop after he left.

1716.87 -> Many of the wiretaps were illegal and warrantless.

1720.32 -> Oppenheimer was questioned about his ties

1722.15 -> to the Communist Party,

1723.14 -> including his affair with Gene Tatlock,

1725.36 -> a Communist party member

1727.04 -> while he was leading the Los Alamos lab.

1729.92 -> He was essentially accused of treason and espionage.

1734.032 -> In December, 1953,

1736.04 -> Oppenheimer had his security clearance suspended.

1739.134 -> His face now grim and in black and white

1742.009 -> was once again on the cover of time.

1745.07 -> His security hearings were international news.

1749.75 -> In 1964, German playwright Heinar Kipphardt

1753.29 -> wrote a play about Oppenheimer's life.

1756.47 -> Oppenheimer was sent a copy of this script,

1759.2 -> and he hated it so much that he threatened to sue.

1762.77 -> He especially despised the final scene where the character

1765.54 -> of Oppenheimer realizes the evil of his work.

1769.34 -> And I quote,

1770.487 -> "We have been doing the work of the devil."

1773.57 -> To Oppenheimer, it was always more complicated than that.

1777.32 -> - I think that it probably was assumed,

1780.26 -> it certainly was always assumed at Los Alamos

1782.919 -> that if the war were not over and not clearly

1792.47 -> to be brought to a conclusion by the diplomatic means

1798.94 -> this weapon would play a part.

1801.23 -> At the time, the alternative,

1806.3 -> the campaign of invasion was certainly much more terrible

1810.23 -> for everyone concerned.

1813.44 -> I think that Hiroshima was far more costly in life

1821.18 -> and suffering inhumane than it needed to have been,

1827.21 -> to have been an effective argument for ending the war.

1833.51 -> This is easy to say after the fact.

1836.54 -> - In 1965, he was asked about the recent proposal of talks

1839.87 -> with the Soviet Union to halt the proliferation

1842.45 -> of nuclear weapons,

1843.38 -> and his response was,

1844.857 -> "It should have been done the day after Trinity.

1848.18 -> Later that same year, he was diagnosed with throat cancer.

1851.57 -> He was a lifelong smoker,

1853.295 -> and he died on the 18th of February, 1967 aged 62.

1865.19 -> Advances in science and technology have given humans

1867.951 -> tremendous power to make the world better or worse,

1872.24 -> and nuclear war isn't the only thing we have to worry about.

1875.48 -> Human caused climate change poses a serious threat to

1878.63 -> ecosystems and the most vulnerable people around the world.

1882.38 -> As I record this, we are in the midst of a heat wave,

1885.29 -> and my folks up in Canada are suffering

1887.12 -> in the smoke from wildfires.

1889.07 -> This is where this video sponsor Wren comes in.

1891.723 -> Their mission is to take action on climate change.

1894.712 -> On their website, you can calculate your carbon footprint,

1897.59 -> which can help you identify ways to reduce your impact.

1900.53 -> And if you like,

1901.64 -> you can offset your carbon footprint

1903.59 -> with a simple monthly subscription.

1905.78 -> While individual action is important,

1907.88 -> Wren understands that this alone is not enough,

1911 -> which is why your subscription funds

1912.56 -> not only carbon removal and offsets,

1914.87 -> but also lobbying to enact climate policy

1917.66 -> and land conservation projects.

1919.97 -> I am particularly fond

1921.23 -> of their new refrigerant destruction project.

1924.11 -> We actually made a video about Thomas Midgley

1926.84 -> who invented Freon,

1928.46 -> which is a refrigerant that is both destructive

1930.77 -> to the ozone layer and a very potent greenhouse gas.

1934.73 -> Well this project permanently destroys

1936.68 -> harmful refrigerants like CFCs, HCFCs,

1939.407 -> and HFCs to stop them from getting into the atmosphere.

1942.86 -> And this will reduce global warming and prevent the further

1945.442 -> destruction of the ozone layer.

1947.21 -> It's a win-win.

1948.043 -> I personally offset my emissions with Wren,

1950.6 -> and for the first a hundred people to sign up

1952.22 -> using the link in the description,

1953.394 -> I will personally pay for the first month

1955.79 -> of your subscription.

1956.84 -> This is an idea I came up with myself

1959.03 -> because I think it's so important that for those of us

1961.43 -> who can help,

1962.27 -> that we pool our resources together

1963.74 -> to have a greater impact.

1965.18 -> So I hope you take the time to check out Wren.

1967.46 -> I wanna thank them for sponsoring this part of the video,

1969.74 -> and I wanna thank you for watching.

Source: https://www.youtube.com/watch?v=Xzv84ZdtlE0