are we the only living things in the
entire universe the observable universe
is about 90 billion light-years in
diameter there are at least 100 billion
galaxies each with 100 to 1000 billion
stars recently we've learned that
planets are very common - and there are
probably trillions and trillions of
habitable planets in the universe which
means there should be lots of
opportunity for life to develop and
exist right but where is it
shouldn't the universe be teeming with
spaceships let's take a step back even
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if there are alien civilizations in
other galaxies there's no way we'll ever
know about them basically everything
outside of our direct galactic
neighborhood the so called local group
is pretty much out of our reach forever
because of the expansion of the universe
even if we had really fast spaceships it
would literally take billions of years
to reach these places traveling through
the emptiest areas in the universe so
let's focus on the Milky Way the Milky
Way is our home galaxy it consists of up
to 400 billion stars that's a lot of
stars roughly 10,000 for every grain of
sand on earth there are about 20 billion
sun-like stars in the Milky Way and
estimates suggest that 1/5 of them have
an earth-sized planet in its habitable
zone the area with conditions that
enable life to exist if only 0.1% of
those planets Harvard life there would
be 1 million planets with life in the
Milky Way but wait there's more the
Milky Way is about 13 billion years old
in the beginning it would not have been
a good place for life because things
exploded a lot but after one to two
billion years the first habitable
planets were born earth is only 4
billion years old so there have probably
been trillions of chances for life to
develop on other planets in the past if
only a single one of them had developed
into a space traveling super
civilization we would have noticed by
now
what would such a civilization look like
there are three categories a type one
civilization would be able to access the
whole energy available on its planet in
case you're wondering we're currently
around 0.73 on the scale and we should
reach type 1 sometime in the next couple
of hundred years type 2 would be a
civilization capable of harnessing all
of the energy of its home star this
would require some serious science
fiction but it is doable in principle
concepts like the Dyson Sphere a giant
complex surrounding the Sun would be
conceivable type 3 is a civilization
that basically controls its whole galaxy
and its energy an alien race that this
advanced would probably be godlike to us
but why should we be able to see such an
alien civilization in the first place if
we were to build generation spaceships
that could sustain a population for
around 1,000 years we could colonize the
whole galaxy in 2 million years sounds
like a long time but remember the Milky
Way is huge so if it takes a couple of
million years to colonize the entire
galaxy and there are possibly millions
if not billions of planets that sustain
life in the Milky Way and these other
life-forms have had considerably more
time than we've had then where are all
the aliens this is the Fermi paradox and
nobody has an answer to it but we do
have some ideas let's talk about filters
a filter in this context represents a
barrier that is really hard for life to
overcome they come in various degrees of
scary one there are great filters and we
have passed
maybe it is way harder for complex life
to develop than we think
the process allowing life to begin
hasn't yet been completely figured out
and the conditions required may be
really complicated maybe in the past the
universe was way more hostile and only
recently have things cooled down to make
complex life possible this would also
mean that we may be unique or at least
one of the first if not the first
civilization in the entire universe -
there are great filters and they are
ahead of us this one would be really
really bad maybe life on our level
exists everywhere in the universe but it
gets destroyed when it reaches a certain
point a point that lies ahead of us for
example awesome future technology exists
but when activated it destroys the
planet the last words of every advanced
civilization would be this new device
will solve all of our problems once I
push this button if this is true then we
are closer to the end than the beginning
of human existence or maybe there is an
ancient type 3 civilization that
monitors the universe and once a
civilization is advanced enough it gets
eliminated in an instant maybe there is
something out there that it would be
better not to discover there is no way
for us to know one final thought maybe
we're alone right now we have no
evidence that there's any life besides
us nothing the universe appears to be
empty and debt no one sending us
messages no one answering our calls we
may be completely alone trapped on a
tiny moist mud wall in an eternal
universe does that force scare you if it
does you're having the correct emotional
reaction if we left life on this planet
die perhaps there will be no life left
in the universe life will be gone maybe
forever if this is the case we just have
to venture to the Stars and become the
first type-3 civilization to keep the
delicate flame of life existing and to
spread it until the universe breathes
its final breath and vanishes into
oblivion
the universe is too beautiful not to be
experienced by someone this video was
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