[ominous music]
NARRATOR: Some scientists believe that 440 million years
ago, Earth was hit by a Gamma Ray Burst,
or GRB, a deadly beam of radiation
that devastated life on the planet.
Could you survive if we were struck by a gamma ray burst
again?
In the first minutes after the disaster, billions of people
are already dead or dying in the impact
zone, an area including Africa, Europe, and the Middle East.
Essentially, life on the side of the impact
has been extinguished.
NARRATOR: In Northern England, the lone survivors
are a group of miners who weathered the blast under 4,000
feet of earth and rock.
Now they travel the countryside, living
off canned and other preserved goods.
But they don't realize that the gamma ray burst
has poisoned their food supply.
MARCELO VAZQUEZ: So a gamma ray burst at this intensity
can produce radioactive or activated
isotopes from the food that can be very dangerous.
NARRATOR: The miner's lifeline is thin,
and it's only a matter of time.
[eerie music]
In the Americas, on the side of Earth opposite the impact zone,
the situation is desperate.
[buzzing]
After the gamma ray burst's electromagnetic pulse
zapped electronics, a global power
blackout went into effect.
MICHIO KAKU: The effect of it would
cascade to give you a collapse of telecommunications.
We would see a massive short-circuiting
of all major electrical systems on the planet Earth.
[alarm sounds]
NARRATOR: For people in Atlanta, Seattle, Rio de Janeiro,
and every large North and South American
city in the non-impact zone, power grids are down,
and commerce is frozen.
MICHIO KAKU: You are literally left in the dark without heat,
without light, without food.
NARRATOR: Grocery stores are mobbed,
and desperation sets in as people fight
over a shrinking food supply.
Ventilators, dialysis machines, and backup systems
fail, all but ensuring the deaths of thousands
of hospital patients.
MICHIO KAKU: We live in a bubble.
This bubble is energized by electricity.
But what happens if something pops that bubble?
Without backups, without heat, without food, then you
begin to realize that civilization itself will begin
to degenerate as a consequence.
[ominous music]
NARRATOR: The usual crowds of summer beachgoers
are nowhere to be seen, from San Diego
to Galveston to Daytona Beach.
The few people moving around in the 100-degree heat
are covered from head to toe.
When the gamma ray burst slammed into Earth's atmosphere,
it ripped apart the ozone layer, exposing the survivors
to a new radiation threat.
The ozone layer in our atmosphere
is one of the most beneficial things on the planet.
We have this star in the sky, the sun,
that dumps ultraviolet radiation at us all the time.
It keeps us alive.
But without the ozone, it would cook us and kill us.
ALEX FILIPPENKO: The side of Earth facing it gets
completely depleted of ozone.
All the ozone gets destroyed, essentially zero left.
Now, you've still got 100% on the other side of Earth.
But as the atmosphere mixes together in the ensuing days
and weeks, effectively, what you'll
have is 50% of the normal ozone throughout the world.
TREVOR VALLE: If you go out in the weeks
after this event with any kind of unprotected skin,
you're getting doses of UV radiation
that would take you normally hours in minutes.
You're talking a serious sunburn in 10, 15, 20 minutes,
life-threatening if you're exposed for hours.
This is a get inside or perish situation.
ALEX FILIPPENKO: The long-term effects
are that UV is coming through and interacting
with living cells.
KEVIN GRAZIER: That much larger dose of ultraviolet radiation
will change DNA and can create cancers.
Skin cancers will rise dramatically.
NARRATOR: The only form of protection is to avoid the sun.
MICHIO KAKU: They're going to have to put
on extra heavy-duty clothing.
They're going to have to put on sunglasses.
They're going to have to cover every inch of their body,
realizing that the sun that gives us life and nourishment
is now bathing us in an ultraviolet radiation
that can eventually kill us.
TREVOR VALLE: Lifestyles will change because you
have to in order to survive.
Think of living the entirety of the remainder of your life
inside or underground.
This is what we will have to do to survive.
NARRATOR: As the ultraviolet radiation threatens mankind,
Earth's ecosystems begin to collapse.
Ultraviolet radiation will, over time,
sterilize the upper meters of the Earth's oceans.
TREVOR VALLE: If we were to suddenly remove the top 30
feet of life-giving food in the ocean,
everything else will begin to suffer.
It's what we call a trophic collapse.
The food chain itself collapses, taking
everything else out with it.
BRIAN THOMAS: The phytoplankton in the ocean
are basically little green plants, single-celled plants.
And they produce about half the world's
oxygen, which means they're the base
of the food chain in the ocean.
Larger things eat them and so on up the food chain.
Fishermen accustomed to harvesting
large bounties of fish from the ocean
would see something very different.
They would see a massive die-off.
[ominous music]
NARRATOR: Without adequate food and water or electrical power,
North and South American cities in the non-impact zone
are now in peril.
Food supply-- average city community has,
at most, about two weeks worth of food on hand.
You go without any significant caloric intake
after about two weeks, then you start
becoming more susceptible to disease and dying.
MICHIO KAKU: We are children when
it comes to understanding gamma ray bursts, their history.
Maybe, just maybe, it's happened many times in our history.
We don't know.
We didn't think that there could be rocks from heaven coming
down, killing the dinosaurs.
But now we know better.
How many more gamma ray bursters are just waiting to fire?