On these African plains some 60,000 years ago our ancestors began migrating north.

A trek that would ultimately give rise to modern day civilization. And it's nothing short of

a miracle that we've progressed as far as we have, especially in such a short amount

of time. It's really not that difficult to see why intelligent life may be extremely

sparse across the universe given how absurdly fortunate we've been. So many things could've

gone wrong along the way and so many times it almost did.

On the morning of the 12th of August, 1883, Mexican astronomer, José Bonilla, was observing

the Sun when numerous UFOs began to sweep across the solar disk. The objects were surrounded

by a coronal haze and left behind a trailing mist. The phenomenon continued for two consecutive

days and Bonilla counted 447 objects in total. As the event could not be explained the UFOs

were simply dismissed as birds, insects, or dust passing in front of the telescope.

But based upon Bonilla's description of the event coupled with an improved understanding of various

astronomical phenomena, an article published in 2011 hypothesized that the objects where

fragments of a comet nearly colliding with the Earth. The only bodies in the solar system

that leave trails and are surrounded by a bright haze are comets. And much like this

comet observed in 2006, we now know that fragmentation is a frequent occurrence. It is estimated

that the comet broke into more than 3,200 fragments ranging in size between 50-1000

meters in diameter and sailed past the earth at a distance of no more than a few thousand

kilometers. Had only one of these fragments struck the planet, it could have resulted

in millions of casualties. Had all or at least a significant portion of the fragments impacted

the Earth, we're looking at an extinction level event.

It's the middle of the Siberian taiga, around 7:00 AM, when a powerful explosion would lit

up the sky. An eyewitness 65 kilometers away from the blast accounts that:

"...the sky split in two and fire appeared high and wide over the forest. At that moment I became so

hot that I couldn't bear it, as if my shirt was on fire... I wanted to tear off my shirt

and throw it down but then the sky shut closed. A strong thump sounded and I was thrown a few meters."

Two decades later in 1927, the first expedition to the blast site would capture this footage.

Some 2000 km² of forest, some 80 million trees in total, had been completely

fattened by the event. The broad consensus is that an asteroid or comet, less than 200 meters wide,

exploded a few kilometers above ground and produced a fireball as demonstrated in this simulation.

Transposed over New York City its destructive power becomes a lot more apparent.

[Edward Lu] This one is a little bit harder to say. The one that..

Over Tunguska, the one that was slightly larger. Had that happened over a city.

Let's say New York City, we would have 7 million casualties.

At least, whatever the population of New York City is, they would be gone.

[Bill Nelson] Really?

While the two bombs dropped on Japan marked a dramatic end to the war, they also marked the beginning

of an entirely new kind of fear. A fear of annihilation by incompetence. Humans are fallible.

We make mistakes. And knowing this, coupled with the realization that one mistake could

result in apocalyptic levels of destruction, the likes of which had so far been reserved

by nature, this new kind of fear was undeniably justified.

In early October of 1960 a new early warning system on Greenland had just become operational.

In the event that the Soviet Union should launch an attack against the United States,

a level 5 warning would be sent to the command center located in Colorado. On October the 5th,

the number on the display suddenly changed from 0 to 1. Indicating that a low-risk unidentified

object had been detected. A bit strange but no immediate cause for alarm. But then the

number continued to climb until a level 5 warning was issued, meaning that long-range

missiles would strike the United States in less than 20 minutes. The alert quickly worked

its way up the chain of command and a slight panic ensued. But it was quickly eased by

the realization that Nikita Khrushchev, leader of the Soviet Union at the time, was currently

visiting the United States. Not exactly where you'd expect him to be in the event of a nuclear attack.

20 minutes passed and the value of bottle caps remained the same. A subsequent

investigation revealed that the base on Greenland had mistaken the rising Moon for an incoming Soviet attack.

In the early morning of January the 24th, 1961, an American B-52 bomber carrying two

hydrogen bombs crashed into an empty field in the state of North Carolina. Officials

quickly issued a report stating that there was no cause for alarm and that there was

no danger of a nuclear explosion or radiation. However, declassified documents released in

2013, reveal that one of the two bombs actually came extremely close to a full scale detonation.

Three out of four safety switches erroneously activated upon impact with the ground and

the slight separation of two wires was the only thing standing in the way of a nuclear

explosion. Had this 3.8 Mt bomb detonated, and had the wind condition been just right,

the radioactive fallout could've reached Washington, Philadelphia, and even New York.

In the early 1960s, tensions between the US and the Soviet Union is strained to the breaking

point and culminated in a situation known as the Cuban Missile Crisis. It is perhaps

the closest we've ever come to committing omnicide. The short version is that the US

installed nuclear missiles near the Soviet union, specifically in Turkey, so in response,

the Soviet Union installed nuclear missiles near the United States, specifically in Cuba.

The US would have none of that. "Hey, you can't do that! Only we are allowed to do that!"

said the United States. "I don't know what you're talking about?" the Soviet Union replied.

I'm paraphrasing of course as these where classified communications.

While the impasse in and of itself came extremely close to disaster,

one specific event stands out. After the US imposed a blockade to prevent the Soviet Union

from exporting even more missiles to Cuba, a Soviet submarine was detected near Cuban

shores. In an attempt to force the submarine to surface so that they could have a friendly

chat, multiple US naval destroyers dropped low intensity explosives to signal the submarine

to surface. However, the captain of the submarine misinterpreted this as an attack and ordered

his men to retaliate against one of the US destroyers by launching a nuclear-armed torpedo.

Fortunately, one of the two senior officers aboard disagreed with the captain's decision

and eventually managed to convince him that they should surface and await orders form

Moscow. And that's exactly what they did and thus the apocalypse had to reschedule.

On May the 23rd, 1967, all of the early warning systems across the United States ceased to function.

In fact, all manner of military communications and radar technology malfunction

simultaneously and it was interpreted as intentional jamming by the Soviets. Bomber planes immediately

scrambled and prepared to launch an attack. But as luck would have it just a few years prior, a branch of the US

military had begun observing solar activity and its effects on the Earth. And on this

day in 1967, the Sun had ejected a powerful solar storm that had stuck the planet and

knocked out military defenses and other equipment. Had a project for something as unrelated as

studying the Sun been delayed for just a few years, no one could've explained this nationwide

interference in time to prevent World War III.

In the mid 1980s squadrons of US aircrafts would often fly straight towards Soviet airspace,

thus triggering their early warning systems, only to turn around at the very last moment.

A form of psychological warfare that kept the Soviets on edge for an attack. In the

early hours of September the 26th, 1983, the command center just outside Moscow was awoken

by the sound of an alarm.

An intercontinental ballistic missile had just been launched by

the US and was now heading towards the Soviet Union. In the event of a nuclear attack by

the Americans it was standard procedure to launch an immediate counter-attack. It was

now up to the man in charge, Stanislav Petrov, to contact his superiors and to inform them

that a nuclear attack was imminent. A few minutes passed when four additional missiles

were detected. However, Petrov decided to go against his training and did nothing.

He reasoned that if the United States were to strike, the attack would likely involve hundreds

of missiles, not just a few. In other words, he suspected that this was a false-alarm.

But as he had no way of confirming his suspicions, he could only wait and hope for the best.

Fortunately, Petrov was correct in his assumption as evident by the fact that you are currently

breathing and a subsequent investigation revealed that sunlight, reflecting of off high altitude

clouds, was responsible for the anomaly.

On March the 31st, 1989, two American astronomers discovered that a week prior, on March the 22nd,

a 300 meters wide asteroid had come fairly close to the Earth. It had not come

close enough to pose any risk of impact and was even further away than the Moon but it's

still worth a mention as it passed through the exact position that the Earth had occupied

a mere six hours prior. Which is in and of itself extraordinarily close on the comic scale.

An impact with an asteroid of this size would obliterate almost everything within

a radius of 60-75 kilometers. Superimposed over Tokyo, one of the largest cities on Earth,

it looks like it would've been a rough day.

Some of you may remember that a few years ago there was a lot of eschatological prophecies

that the world would end in 2012. While the world is still spinning, as evident by the

rotation of this globe, we did narrowly escape a catastrophic event in July of 2012. On the

23rd of July the Sun expelled something known as a coronal mass ejection or CME for short.

A CME is a release of large quantities of magnetized plasma and if it strikes the Earth

it can cause some serious damage to any and all electronic devices.

This was also one of the most powerful CMEs in recorded history.

And it blasted straight through the Earth's orbit.

Luckily for us, the Earth was on the other side when that eruption occurred but

due to the rotation of the Sun, had this eruption occurred just 9 days prior, we would've been

engulfed by that storm. If that had happened, and there's a 12% chance that it will happen in the

next 10 years, it could've taken us as much as a decade to fully recover. It's difficult

to overstate the ramifications of a CME on this scale. Worldwide power outages would

take weeks, months, or even years to resolve. Many satellites would have to be replaced.

Electronic equipment of all kinds would cease to function seemingly over night.

Medical, transportational, financial, military, national security, and other critical systems would

all be compromised or destroyed. Society would grind to a halt...

...and be literally plunged into darkness for years to come.

Given how dependent we've become on electricity and various technologies

like the internet, it's difficult to image anything but global panic and chaos. It would

not have been the end of the world but it would no doubt have felt like it.

Declassified documents reveal that the US military has had over a thousand close calls

with nuclear weapons since the 1950s. Over a thousand times when cataclysmic devastation

was just narrowly avoided. And who knows how many near accidents the Russian military have

experienced or any of the other nuclear weapon states. Coupled with the destructive power

of natural events, it is truly a miracle that we've come as far as we have.