You've seen it in the movies.
Contact with aliens
often ends badly for humans.
So why do we keep
trying to get in touch with them?
We don't even know if aliens really exist.
But if aliens do exist,
and if they're advanced enough
to detect our existence,
chances are they're doing one of two things.
Either they're avoiding us,
or they're on their way.
But the most important question is,
Will they come in peace?
Whether you like it or not,
the search for alien life began a long time ago.
In 1960, astronomer Frank Drake
used interstellar radio waves to scan
distant planetary systems for signs of life.
The scans came back empty.
In 1977, we launched probes that contained
audio recordings of Earth,
diagrams of the human body,
and the location of our Solar System.
The probes reached interstellar space in 2012.
But we still haven't heard
from any aliens yet.
And then, betting on the fact that
they're closer than we think,
Doritos made history in 2008
by broadcasting
the first ever video advertisement
intended for potential extraterrestrial life.
As usual, radio silence from the other end.
Are aliens just not interested in us?
Or are they coming for our snacks?
Are we going to regret
broadcasting our existence into space?
To calculate how many
alien civilizations might exist in our galaxy,
astronomers often use the Drake Equation.
Not that Drake.
The Drake Equation basically takes
every known star and planet in our galaxy,
and filters them through a list of criteria.
It determines whether or not
they could host and sustain
a functioning civilization.
Of course, there's too much uncertainty
to come up with an accurate figure.
Another problem is that our galaxy
has a diameter of about
150,000 to 200,000 light-years.
Communicating within a galaxy of this size
becomes a challenge when you realize
any message we send
might be ages old
by the time it's received!
If we sent a message to a star system
that was 100 light-years away,
a whole century would pass on Earth
by the time our alien neighbors
got the message.
So whatever we decided to broadcast,
we'd have to make sure it represented
the unified intentions of the world,
and that it could stand the test of time.
But now we have to consider
the possible responses.
First of all,
for any alien species to be able to
receive and respond to our messages,
they'd have to be at least as smart as we are.
They would also have to be
technologically capable of receiving
a radio or laser transmission.
But what if aliens received our messages
and simply chose not to answer?
Some civilizations may protect themselves
by living in secrecy to avoid being detected,
and potentially destroyed, by rival civilizations.
This is known as the Dark Forest theory,
in which any contact with outsiders
is considered dangerous.
It's also possible that aliens
have received our messages
and are simply watching and waiting
for humans to self-destruct
before they come and colonize Earth.
In the absolute worst-case scenario,
aliens have received our messages,
and they're on their way to Earth now.
Forget what you saw
in the movie "Independence Day."
"Mankind, that word should have new meaning for all of us today."
"We can't be consumed by our petty differences anymore."
An alien invasion would not
be a good opportunity
for humanity to unite
against a common enemy.
There wouldn't be enough time!
If an alien species is advanced enough
to reach Earth from their home planet,
they're far more advanced than we are.
We don't yet have the technology
or the infrastructure
to defend against such an invasion,
and we probably won't for some time.
So if we were to get attacked by aliens,
humanity would easily be wiped out
before we could form a globally united front
against our invaders.
But why do we always assume
that aliens are going to be violent?
For all we know,
intelligent alien life might
receive our messages
and want to work with us.
Of course, we could come up with
a whole number of possibilities
of how making contact with aliens
might play out.
But keep in mind that we've been
broadcasting signals into outer space
since the sixties,
and we have yet to receive a reply.
For now, we just have to wait and see.
Are we alone in the Universe?
Should we be expecting
visitors anytime soon?
And just so you know,
aliens aren't the scariest thing
in the infinite void of space.
Do you know what would happen
if a magnetar entered our Solar System?
Well, that's a story for another WHAT IF.