In 1943, the US government essentially borrowed
about 14 ,000 tons of solid silver from the treasury.
They built a hidden city larger than most state
capitals, and they employed tens of thousands
of people who were completely in the dark about
what they were actually doing. Right, which is
just wild to think about today. Exactly. I mean,
we usually think of a multi -billion dollar industrial
empire as something that takes, you know, decades
of slow growth to build. But this was an operation
the size of the entire American automobile industry,
constructed from scratch almost overnight. and
somehow it remained the absolute best -kept secret
of the Second World War. It really is a logistical
reality that kind of defies conventional understanding.
We are talking about taking a purely theoretical
concept, something that up to that point only
existed as math on university chalkboards, and
willing it into a physical world -shattering
reality in under 40 months. It's nuts. So welcome
to this deep dive. Today we have a massive stack
of source material in front of us detailing the
Manhattan Project, and our mission for you listening
right now is to cut through that overwhelming
mountain of history. We want to extract the most
mind -boggling logistical, scientific, and human
muggets of this whole endeavor. There is definitely
a lot to sort through. Yeah, so okay, let's unpack
this. To me, building the atomic bomb was like
trying to assemble an airplane mid -flight while
blindfolded, because these scientists and engineers,
they had to invent the underlying physics and
the massive industrial manufacturing processes
to support that physics at the exact same time.
Yeah, that's a great way to put it, because to
understand that transition from a theoretical
fear to a boots -on -the -ground military operation,
you really have to look at the timeline. The
initial spark was in 1938. Right, the discovery
of nuclear fission. Exactly. German chemists
Otto Hahn and Fritz Strassmann discover fission.
And the immediate terrifying realization among
the global scientific community, many of whom
by the way had recently fled fascist regimes,
was the sheer amount of energy released when
a uranium atom splits. Missing mass was converting
directly into energy. Which is Einstein's whole
E equals MC squared thing in action. Precisely.
And the underlying fear was that Nazi Germany
could turn this brand new physics into a weapon
of just unprecedented scale. Which prompts that
famous 1939 letter, right? From Albert Einstein
and Leo Szilard to President Roosevelt, basically
urging him to secure uranium ore and fund chain
reaction research before the Axis powers beat
them to it. Right. So Roosevelt creates an advisory
committee, but the American effort actually languished
for a bit. It was really British scientists working
under what was called the MAU committee, who
provided the crucial breakthrough in 1940. Oh,
wait, really? The British did the initial math.
Yeah, they did. Because before this, scientists
assumed a bomb would require tons of uranium,
like literally tons, meaning it could only be
delivered by ship, which makes it strategically
really clunky. But the MOU committee calculated
the fast neutron cross sections of uranium -235,
and they realized the critical mass wasn't tons
at all. It was small enough to fit inside a contemporary
bomber plane. Oh, wow. So suddenly it's mobile.
Exactly. that shifted the paradigm entirely.
It wasn't just a fascinating lab experiment anymore.
It was an actionable military necessity. And
when a project becomes a military necessity,
the U .S. Army assumes control. They form the
Manhattan district and they bring in General
Leslie Groves to run it. And I found his initial
reaction in the sources incredibly telling. Oh,
he was furious. Yeah, he is handed this world
saving top secret project, and he's absolutely
livid because of his priority rating. Right,
because the wartime military operated on a very
strict supply priority system. Groves was initially
handed an AA3 rating. Which means what, exactly,
in practical terms? Well, to put it in perspective,
that was the exact same priority rating given
to a standard run -of -the -mill TNT plant. You're
kidding! No. And Groves recognized instantly
that you cannot commandeer the massive steel,
concrete, and electrical resources needed for
a sprawling, unprecedented scientific empire
on an AA3 rating. So he marched into the war
production board and essentially bullied the
chairman into granting the project the top -tier
AAA rating. Skipped right to the top. Yeah, which
gave him the power to seize whatever resources
he needed anywhere in the country. Okay, but
I have to jump in here on Groves' next major
decision because it makes absolutely no sense
to me. Groves is a by -the -book military engineer,
right? He is obsessed with security and chain
of command, and he decides to hand the keys to
the bomb design lab at Los Alamos to J. Robert
Oppenheimer. It is definitely the oddest pairing.
I mean, how did the military brass let him get
away with that? Oppenheimer was this avant -garde
theoretical physicist. He had known communist
associations, zero administrative experience,
and he didn't even have a Nobel Prize, like half
the money he was supposed to be managing. It's
true. On paper, Oppenheimer was a walking red
flag, military intelligence actively trying to
block his clearance. But Groves possessed an
incredibly ruthless eye for utility. What do
you mean by that? Well, during a long train ride
in 1942, Groves realized that Oppenheimer was
the only scientist who fully grasped the entire
interdisciplinary nightmare of the project. He
understood the theoretical physics, yes, but
he also understood metallurgy, chemistry and
the logistical challenges of building a remote
laboratory. So he just saw the big picture. Exactly.
Groves personally overruled his own security
apparatus to waive Oppenheimer's clearance. He
knew they were complete opposites. grows the
pragmatist, the abenheimer, the visionary. But
they shared this relentless driving ambition
to see the project through. But even with that
ambition, I mean, they couldn't just rent laboratory
space in downtown Chicago. The danger, the radiation
and the sheer scale of the manufacturing meant
they had to physically build a hidden empire
from scratch. They really did. They created massive
secret installations. Oak Ridge, Tennessee, expanded
from rural farmland into a heavily guarded city
of seventy five thousand residents. It consumed
massive amounts of the nation's electricity.
Just out of nowhere. Out of nowhere. And Hanford,
Washington displaced farmers and Native American
tribes to build a colossal reactor site. They
operated a transport fleet of over 900 buses,
which, by the way, was more buses than the entire
city of Chicago had at the time. That is staggering.
And Los Alamos was just constructed on an isolated
mesa in New Mexico, right? On the site of a former
ranch school. The need to know policy groves
instituted across these sites is legendary. I
mean, they peaked at 130 ,000 workers. Here's
where it gets really interesting for you listening.
It's like having thousands of people baking individual
ingredients in separate kitchens, but only one
guy in the country knows they're actually assembling
a cake. That is the perfect analogy. Compartmentalization
was the absolute bedrock of their security apparatus.
Workers only knew the specific task directly
in front of them. The most striking example of
this is the calatron girls at Oak Ridge. Oh,
I love this story. Yeah. These were young women,
like Gladys Owens, hired to sit on tall stools
and monitor arrays of dials and switches. Their
instructions were remarkably simple. They just
had to keep a needle in a certain range by turning
a knob. And they had absolutely no idea they
were operating electromagnetic isotope separators.
None whatsoever. They were operating calutrons,
which used massive magnetic fields to bend the
flight paths of uranium ions. Because the desired
uranium -235 atom is slightly lighter than the
common uranium -238 atom. Its trajectory bends
just a fraction tighter in a magnetic field.
So it basically gets caught in a separate pocket.
Exactly. These women were enriching uranium for
a nuclear weapon, and they thought they were
just keeping a dial steady. Which brings up the
sheer logistical audacity of those catalytrons.
I want to talk about my absolute favorite detail
on this entire stack of sources. The copper shortage?
Oh, the silver, yeah. Right. To generate those
massive magnetic fields at Oak Ridge, they needed
thousands of tons of copper for the electromagnetic
coils. But copper is heavily rationed for artillery
shell casings for the war. So what do they do?
They look for the next best electrical conductor,
which happens to be silver. So the Manhattan
Project brass simply goes to the US Treasury
and asks to borrow silver. And the response from
the Treasury is just... peak bureaucracy. It
really is. When the project's representatives
asked for thousands of tons of silver, the undersecretary
of the treasury reportedly informed them Young
man, you may think of silver in tons, but the
Treasury will always think of silver in troy
ounces. That is so good. But you know, that AAA
priority rating won out. They ultimately withdrew
14 ,700 tons of solid silver bullion from the
West Point Depository, melted it down, and drew
it into wires for the magnetic coils at Oak Ridge.
Just casual borrowing of the nation's wealth
to build a machine nobody is allowed to know
about. But seriously, how was it practically
possible to keep an operation of this magnitude
completely off the radar of the press and access
powers. It came down to extreme consequences
and sheer geographical fragmentation. The threat
hanging over the workforce was severe. We're
talking 10 years in prison or a $10 ,000 fine
for disclosing secrets. Wow. Security forces
aggressively investigated over 1 ,500 loose -talk
cases, but the primary defense was the fragmentation
itself. Even if a spy learned what was happening
in one building at Oak Ridge, it wouldn't tell
them what was happening at Hanford or Los Alamos.
But all those secret cities, all that silver,
all that intense security, I mean, it was ultimately
useless unless the science actually worked. And
the science was proving incredibly hostile. They
were forced to pursue two completely different
paths to a bomb simultaneously. Right, because
they weren't sure which would work. Exactly.
Path one was enriching natural uranium -235 at
Oak Ridge. Path two was breeding a brand new
man -made element called plutonium in the world's
first industrial scale nuclear reactors at Hanford.
And both paths push the absolute boundaries of
physics and engineering. At Hanford, the B Reactor
was completed in September 1944. They power it
up. It goes critical. The cooling water is flowing.
Everything looks absolutely perfect. And then
just hours later, the power level mysteriously
drops, and the reactor completely shuts itself
down. The panic in that room must have been absolute.
Oh, they thought they had fundamentally misunderstood
the physics. It took physicists Chen Shengwu
and Enrico Fermi to deduce the problem. A byproduct
of the fission process was a radioactive isotope
called xenon -135. OK, what does that do? Well,
it turns out xenon -135 has an abnormally large
neutron capture cross -section. It essentially
acts like a massive sponge for neutrons, eating
up the needed to sustain the chain reaction.
The reactor was choking on its own exhaust. And
the only thing that saves the entire plutonium
project is a totally random act of corporate
over -engineering. The DuPont engineer named
George Graves had insisted on adding 504 extra
tubes to the reactor design, going completely
against the scientists' exact blueprints just
to be safe. Because of those extra tubes, they
could load in enough extra uranium to push through
the xenon poisoning. It's incredible. If Graves
hadn't ignored the theoretical physicists and
trusted his engineering instincts, the Hanford
reactors would have been a billion -dollar failure
and the plutonium bomb would have been severely
delayed. But even with the reactors running,
the Los Alamos team faced a crushing realization
in the summer of 1944 regarding the plutonium
itself. The fizzle problem. Yeah. What exactly
was that? So they discovered that reactor -bred
plutonium contained an isotope, plutonium -240,
which has a very high rate of spontaneous fission.
It was just too highly reactive. If they used
it in a simple gun -type bomb design, where you
basically shoot one subcritical mass into another
to initiate the explosion, the plutonium would
predetonate. Meaning it would just blow its a
part too early. Exactly, it would melt itself
into a puddle before yielding a full nuclear
explosion. So they are forced to pivot to an
incredibly complex implosion design for the plutonium
bomb, which becomes the Fat Man. To visualize
this for you listening, a gun type bomb is simple,
shooting a bullet into a bullet. But an implosion
design is like taking a tennis ball and trying
to crush it perfectly from all 360 degrees simultaneously,
so it condenses into the size of a marble. If
you don't squeeze it perfectly evenly, it just
bulges out the sides. And the precision required
to achieve that symmetrical compression in real
life was staggering. You cannot just pack TNT
around a core and light it. They had to design
explosive lenses. Lenses? Like for glasses? Kind
of the same concept, yeah. Much like an optical
lens focuses light. These explosive lenses use
alternating layers of fast -burning and slow
-burning conventional explosives. They took a
convex shockwave and turned it into a perfectly
concave shockwave directed precisely at the center.
And not only are they dealing with microsecond
timing on these explosive lenses, they are trying
to machine the plutonium core itself, which is
a nightmare metal. From the sources, it's highly
radioactive, heavily toxic, and pyrophoric. Right.
Meaning if the metal shavings get too warm or
exposed to moisture in the air, they just spontaneously
catch fire. It sounds like an engineering hellscape.
So knowing how impossibly complex the implosion
lenses were and how difficult plutonium is to
work with, why didn't they just scrap it entirely?
Why not stick to the simpler uranium gun type
bomb that they knew would work? It really came
down to a brutal calculation of time versus volume.
Enriching uranium -235 at Oak Ridge was agonizingly
slow. By the summer of 1945, they barely had
enough enriched uranium for one single bomb.
The little boy. Just one. Just one. The Hanford
reactors, however, could breed plutonium relatively
quickly once the xenon issue was solved. If the
military wanted a continuous stockpile of weapons
to force an end to the war rather than just a
single unrepeatable demonstration, they had to
make the plutonium implosion design work. And
because implosion was so theoretically complex,
they couldn't just trust the chalkboard math.
They had to test it in the real world. Which
brings us to the climax, the Trinity test. July
16th, 1945, out in the New Mexico desert. The
anxiety is off the charts. They are so terrified
the implosion will fail and just scatter their
precious heart -earned plutonium into the dirt
that they actually build a massive containment
vessel called Jumbo. Yeah, Jumbo was a 214 -ton
steel cylinder. The initial idea was to place
the bomb inside it. If the conventional explosives
fired, but the nuclear core fizzled, the steel
would contain the explosion, allowing them to
essentially scrape the precious plutonium off
the inside walls and try again. Which is an insane
contingency plan. Totally insane. They ultimately
leave Jumbo empty on a tower nearby, and it actually
survives the blast, proving just how massively
over -engineered it was. But the test itself,
I mean, the 20 kiloton explosion melts the desert
sand into a radioactive green glass called trinitite.
It shattered. civilian windows 100 miles away.
The psychological shift among the scientists
at Trinity was profound. For years, they had
been consumed by the intricate engineering puzzle.
But standing in the desert, seeing a flash brighter
than the sun and feeling the wave of heat on
their faces from miles away, it violently shifted
their creation from an abstract theory to an
undeniable reality. That's when Oppenheimer famously
recalled that line from the Bhagavad Gita, right?
Now I am become death destroyer of worlds. Yes.
It really highlights the existential dread these
brilliant minds were constantly calculating.
I mean, there was a point before Trinity where
physicist Edward Teller raised a theoretical
fear that the massive heat of the bomb might
literally fuse the nitrogen nuclei in the Earth's
atmosphere. Right, sparking a runaway reaction
that would incinerate the entire planet. Exactly.
Hans Beth ran the calculations and proved it
was extremely unlikely, but the mathematical
chance wasn't technically zero. So what does
this all mean for the people pushing the button?
How does a group of human beings proceed with
a test knowing there is even a fractional chance
of ending the world? It speaks to the absolute
terror of the alternative. You have to place
yourself in the geopolitical context of 1942
through early 1945. The assumption driving everyone
from General Groves to the lowest lab technician
was that Nazi Germany was doing this exact same
math. The fear of the Nazis getting it first.
Yes. The existential fear of a fascist monopoly
on nuclear weapons overrode almost every other
dread. By the time Allied intelligence confirmed
Germany's nuclear program had stalled, the momentum
of this $2 billion machine was practically unstoppable.
And the transition from the desert test to deployment
is incredibly rapid. Logistics just shift into
overdrive. The core of the uranium bomb is loaded
onto the USS Indianapolis and rushed across the
Pacific. By August 1945, the uranium bomb Little
Boy is dropped on Hiroshima, destroying 4 .7
square miles and killing up to 140 ,000 people.
Three days later, the plutonium bomb Fat Man
is dropped on Nagasaki through a last -minute
break in the clouds. The sheer suddenness of
the devastation shocked the globe. But the internal
sources reveal it also shocked American leadership.
The military had plans to continue dropping bombs
as they rolled off the assembly line. Wait, they
were just going to keep going? Yes. But on August
10th, the day after Nagasaki, President Truman
was informed that a third bomb would be ready
to drop in a matter of days. Truman immediately
halted further bombings, requiring his express
presidential authority for any future use. According
to his cabinet members, Truman stated he couldn't
stand the thought of wiping out another 100 ,000
people, specifically mentioning the horror of
killing all those kids. The war abruptly ends
shortly after that, but the nuclear box has been
opened. The world is permanently changed. Looking
back at the massive stack of sources on the secret
empire, what was the final bill? The total cost
was roughly $2 billion in 1945. Adjusted for
inflation today, that is about $28 billion. Which
sounds like an astronomical amount of money for
a secret project. But frame this for you listening
right now. That $2 billion was actually equivalent
to less than nine days of total U .S. wartime
spending. Less than nine days. Nine days to build
the atomic age. In the context of the total war
economy, it was a fraction. And 84 % of that
cost was purely infrastructure building the massive
plants at Oak Ridge and Hanford to produce the
fissile material. When you divide up the final
numbers, the ultimate cost came out to about
$500 million per bomb used. And the military
managed to fund this vast enterprise entirely
without alerting the public or congressional
oversight. They hid the money in black budgets
under the most aggressively boring bureaucratic
names imaginable, like expediting production.
And that intense secrecy and unlimited funding
shaped the project's lasting legacy. Manhattan
Project birthed what we now call Big Science.
Meaning what? Well, before 1942, scientific research
was mostly conducted by small teams of professors
in university basements on shoestring budgets.
Afterward, it transformed into the modern, massively
-funded network of national laboratories, places
like Argonne, Oak Ridge, and Los Alamos. It led
to the creation of the Atomic Energy Commission
and the dawn of nuclear medicine, utilizing radioisotopes
for cancer diagnosis and treatment. But there's
a downside, too. A major one. It left a dark
legacy of severe environmental contamination,
most notably the millions of gallons of highly
radioactive waste still sitting in aging underground
storage tanks at Hanford today. It's a fascinating
complex paradox. The exact same military black
budget, the exact same extreme secrecy that created
the most destructive weapon in human history,
simultaneously fast -tracked civilian supercomputing
and life -saving medical therapies. How did this
framework permanently alter how modern scientific
research is conducted? It proved unequivocally
that if a government throws enough money, industrial
resources and brilliant minds at an impossible
problem, it can be solved in record time. But
it also fundamentally severed the link between
scientific discovery and public consent. Interesting.
The physicists at Los Alamos proved that humanity
could harness the fundamental power of the universe.
But the military framework proved that the scientists
themselves would not get to dictate how that
power was deployed. It permanently altered the
power dynamic between the scientific community
and the state. To quickly recap this incredible
journey for you listening, we started with a
theoretical physics letter warning the president,
which triggered a frantic secret race. That race
spawned a two billion dollar hidden empire, birthed
massive secret cities, employed a hundred and
thirty thousand unwitting workers who were kept
completely in the dark and forever altered the
geopolitical and scientific landscape of the
world. It's a monumental achievement of engineering
that leaves us with profound lingering questions
about responsibility and control. And I want
to leave you with one final provocative thought
to mull over regarding that exact point. We discussed
the unstoppable momentum of the project. Well,
in the final weeks before the bombs were dropped
on Japan, a group of scientists put together
what became known as the Franck Report, alongside
the Szilard petition. Dozens of the very same
physicists and chemists who had dedicated years
of their lives to building these weapons drafted
urgent petitions to the president. Desperate
petitions. Yeah. They were warning the government
about the moral responsibility of using the bomb.
They were pleading for a non -lethal demonstration
on a barren island to frighten Japan into surrendering
rather than launching a surprise attack on a
populated city. Think about the weight of that.
The greatest minds of a generation worked around
the clock for years to solve the impossible physics
of this weapon. But when they suddenly realized
the terrifying political reality of their creation,
they found they were completely powerless to
hit the brakes. What happens when the creators
of a technology realize they no longer control
how it is used? It's like we talked about at
the very beginning. They managed to assemble
the airplane mid -flight while blindfolded. But
once the blindfolds came off, they realized they
weren't the ones in the cockpit. profoundly sobering
realization and one that remains incredibly relevant
as we navigate the rapid advancement of emerging
technologies today. Thank you for joining us
on this deep dive. Take care.