- Good morning class, time to put on your tinfoil hats!
The question of whether or not we are alone in the universe
is something mankind has wondered for hundreds of years.
Is there life outside of Earth,
and what would even make that possible?
Well, the following theories explain
why aliens are most likely out there.
Here are 10 credible explanations
why aliens likely exist.
Number 10 is the number of planets.
If we think of life as a phenomenon
which requires a specific set of
environmental factors to occur,
then we can start to work out the probability
of alien life in the universe.
Temperature, material elements, chemistry, and stability,
all of these things play their part.
But the biggest number one factor
necessary for life as we know it
is to have a celestial body, like a planet.
You know, the perfect neighborhood for life to evolve.
Previously, we were not exactly sure
that planets around other stars,
known as exoplanets, actually existed.
But, with the development of the Kepler satellite,
which can detect minuscule changes
in a distant star's light when planets pass in front of it,
astronomers have detected nearly 4000 planets so far.
So, in other words, planets are probably abundant,
and that means that there are plenty of places
for extraterrestrial life to call home.
You know, now that I think about it,
an alien world would probably be perfect.
Why would they wanna come here
with all the farting cows?
It's a thing, Google it.
Number nine is the age of the universe.
In case you didn't know, the universe is about
13.8 billion years old.
Our planet Earth has been around
for about 4.5 billion years of that,
with the oldest evidence of life
being 3.9 billion years old.
It wasn't until about 7 million years ago
that the first hominoids evolved,
and then finally, you get us, the homo sapien,
just a few hundred thousand years ago.
But even within that time, recorded history
is only about 10,000 years old,
probably because we didn't develop writing
until about that time.
Well, you know, that or there were
numerous cataclysmic events
that kept resetting our civilization.
Mama, no!
The point is, even if it takes 4 billion years
to get civilization, the universe is way older than that.
An extraterrestrial species could've become
technologically advanced several times over
during that time, so who knows
how many alien cultures could be out there?
They're probably looking at us right now like,
"They're still using toilet paper?
"They don't know about the shells."
Number eight is the theory of panspermia.
A big challenge in science is to explore the conditions
which led inanimate matter to become self-replicating,
evolving through natural selection.
You know, that little thing called life.
Most theories involve the early Earth environment,
but one theory is a little different.
The theory of panspermia states that life
didn't start on Earth, but instead was brought here.
Now hold on, before you start to think that
ancient aliens did it,
panspermia actually refers to the transference of bacteria.
Microscopic critters were hitchhiking
on an asteroid or comet, which struck the Earth,
depositing life into the seas
billions of years ago.
Furthermore, we know that volcanic eruptions
or large impacts could feasibly throw out
rocky debris into space.
This then spreads life further from planet to planet.
So, it could very well be that we are the aliens ourselves,
and that countless worlds have been seeded, just like ours.
Oh, I just realized what panspermia means.
Get it, volcanoes just.
That's inappropriate.
Number seven are hydrothermal vents.
We know for a fact that life arose
at least once here on Earth,
and we can speculate about other planets
and say it's likely that alien life exists,
but we don't know that for a fact.
However, by studying life here on Earth,
we can increase our confidence.
Now, there are many planets that are nothing like Earth.
In fact, most of them are quite different.
Many of them are too far from their stars
to have temperatures needed for most life, like on Earth.
In fact, some are called orphan planets
and don't even orbit a star at all.
But even these cold worlds may have life.
You know, like ice people walking around.
That's not what that means?
Okay.
Deep at the bottom of our oceans,
there are hydrothermal vents,
which spew heated gas and liquid
from beneath the sea bed.
Around this heat source, a rich ecology of life has evolved
without any sunlight at all.
Astrobiologists hold out hope
that even the remotest planets
have such vents, and who knows what creeps around them?
It's like a little club where all the alien life
can get together and hang on the seabed.
It's a lovely thought.
Number six is the fertile solar system.
We may not need to look very far
to find extraterrestrial life
if our own backyard is anything to go by.
There are several candidates for environments
which could actually support life
around our own solar system, including Mars
and the moons of Jupiter and Saturn.
While so far, Mars seems barren,
there are telling signs that there may be life
under the surface living in water.
Around Jupiter and Saturn, moons such as Enceladus,
may have oceans of water underneath
a thick crust of ice, warmed by the tidal forces
of the huge gas giants they orbit.
Some people have even suggested
that there could be multicellular life,
such as fish-like creatures down there.
If life has evolved several times
across our own solar system,
then this would again support the hypothesis
that the universe should be teeming with life.
You know, if there are infinite
possibilities of civilizations,
then that means that there are infinite possibilities
of what they could look like.
Maybe they have hands growing out their foreheads
and something like that.
It's gonna be a nightmare.
Number five is the resilience of life.
The universe is a hazardous place,
filled with radiation and extremes of temperature
which would wipe out a person in a blink of an eye.
But, when you look at the simple tardigrade,
also known as a water bear,
you realize just how resilient life can actually be,
even when faced with the might of the universe.
These microscopic animals can survive in mud volcanoes,
and at the bottom of the ocean,
and can even withstand anything
between minus 272 and 150 degrees celsius.
It can even survive without food for 30 years,
tolerate 1000 times more radiation
than any other animal, and even survive in space.
30 years without food?
I go 30 minutes without food and I get hangry.
And there are other lifeforms called extremophiles,
which can thrive in even harsher environments.
If life can be this resilient,
then maybe there are all kinds of weird,
almost indestructible creatures
living out there in the vastness of space.
And humans are definitely not one of them,
because I just stub my toe and I cry like a baby.
Mm, fragile.
Number four are the building blocks of life.
Knowing the building blocks of life
can help us identify where it might arise.
For example, scientists theorize
that the molecule hydroxylamine
is a building block of life.
It's comprised of nitrogen, hydrogen, and oxygen,
elements which are common here on Earth.
And astronomers have detected it in abundance
around a star just 1000 light years from our solar system.
So, it's very possible that where we find
the building blocks of life,
hopefully we can find life itself.
But there are also scientific models
based on hypothetical biochemistry
that state that life on other planets
may use different building blocks.
We're carbon-based lifeforms
because there's a lot of carbon on Earth,
but perhaps on another planet,
something like silicon is the most abundant element,
and therefore life could evolve from that.
If that is the case, extraterrestrial life
could exist in many more locations
than we even imagine.
Number three is natural selection.
Evolution may mandate that there is
extraterrestrial life out there,
and not only that, but that there must be life
which has technology and uses it to travel through space.
Natural selection is the cornerstone
principle of evolution.
It's the idea of survival of the fittest,
the idea that organisms adapt to their environments
and eventually thrive because
only the genetic mutations which make survival possible
are actually passed on.
We see it throughout Earth.
Millions of organisms adapted
to their surrounding environments.
So, if we assume that some form of natural selection
leads to simple life elsewhere,
then that same process will, over billions of years,
lead to creatures like ourselves
who can change our environments.
I would love to find out that there are aliens
that survived on a volcanic planet.
Fire aliens!
Sounds badass.
Number two is technology is king.
Okay, we are now heading into some out-there ideas,
but be brave and come with me on this journey.
I won't ask for much.
Maybe your sanity, but that's about it.
We are constantly innovating
and creating new technologies,
and those technologies then lead to other breakthroughs.
There is a philosophical concept
that we are merely the reproductive organs of technology,
creating more of it until that technology
can replicate itself and head out on its own.
Yep, hand over your sanity please.
Arthur C. Clark explored this idea
that space is so vast that we wouldn't actually
ever meet aliens, but instead,
would encounter their technology.
If there are aliens out there,
they may be pieces of technology
which replicate and explore the universe.
In this way, one alien civilization
could give birth to millions of others.
And I'm fine with this, as long as
they aren't the Terminator or the Borg.
That would suck for us.
And number one is the strong anthropic principle.
The strong anthropic principle states
that the reason we exist in this universe
is because our universe makes life likely.
It's organized in such a way
that all the laws of physics
make sentient, intelligent, technology-building creatures
probable at some point.
The mathematician James England
has even developed a mathematical theory
which states that life has to happen,
that it's as miraculous as a rock
rolling down a hill.
It will happen because our universe
has all the right parameters to make it so.
If this is the case, then it's very likely
that we are not alone in the universe.
And now you know, you may take your tinfoil hats off, class.
So, that was 10 credible explanations
why aliens likely exist.
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Thank you guys for watching and I'll see you
on the other side.
Time to take off!