Detectable Civilizations in our Galaxy 5

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Detectable Civilizations in our Galaxy 5 : More reasons why we haven't detected anything yet.

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In the last video on the Drake equation
we tried out some numbers
we just made some assumptions
that seemed reasonable at least to me
and we got that there should be 12.5
detectable civilizations in the Milky Way Galaxy
and I've talked about a bunch of reasons
about why we are not detecting them
but I left out one of the most obvious reasons
that we are not detecting them
and it was rightfully pointed out in the comments
bellow that video
and thats just the signal might be too weak
if theres 12.5
if there's on the order of 10, 11, 12 detectable
civilizations in our galaxy
they could be quite far from us
this isn't the Milky Way
but this is a galaxy that probably doesn't look
too different from our Milky Way
we could obviously never get this vantage point
of our galaxy
well at least not for a while
not unless we can travel quite far away from it
but lets say we are over here
you could imagine if the ten civilizations
or the twelve civilizations are
here, one, two, three, four
there's probably a lot more at the center actually
because that's where our density is higher
so let me put it here
so one, two, three, four, five, six, seven
eight, nine, ten, eleven, twelve
the closest of them might be
tens of thousands of light years away from us
and there might be a lot of stuff in between
all sorts of crazy things happening
stars exploding
all sorts of signals that we are receiving
and it might just be
that the signals from those civilizations
are too weak to reach us
or that there is too much interference
from all of the other craziness
that's happening around the galaxy
there's also these other reasons
that I've talked about in the last video
maybe they've gone beyond
using radio as a form of communication
and thats why..
or they never used it to begin with
and that's why we don't even see them
ever using it
or they used if for a very short period
a kind of transition period
and maybe in a hundred years we'll discover the next best thing
the other idea behind why we're probably
or maybe why we might not be able to detect civilizations
is that
well there might be a lot fewer than ten
when I did the Drake equation right over here
I just made a bunch of assumptions
none of these seemed crazy
but I assumed a reality
where you didn't have these kind of cataclysmic events
in the galaxy at regular intervals
but we know there are cataclysmic events
that happen in our galaxy
in other galaxies
the one we know the most about
although there are all sorts of things that we
don't know much about
are gamma ray bursts
and these are still kind of trying to be understood
GAMMA RAY BURSTS
and you can watch the video on quasars
those are essentially of highly energetic rays
being released when all this material
is being kind of absorbed into super massive black holes
at the centers of galaxies
that tend to be very very very often
billions of light years away
and gamma rays are one of the things that get emitted from those
but you can also have gamma ray bursts within galaxies
we believe maybe certain types of stars when they collapse
into black holes
you have this burst of gamma rays
there might be certain kinds of neutron stars
with the right properties that might every now and then
release gamma rays
and the view is
is that if there is a civilization
that is within a few thousand light years
near one of these gamma ray bursts
and its in wrong place
its kind of in the path of the burst
then its a good chance that those civilizations will
be completely wiped out
that those planets will become sterilized
because there is so much radiation
coming out from that gamma ray
there's even some theories
that some of the extinction events that have happened in Earth's history
we are not talking about the dinosaurs
we are talking about billions of years ago
maybe a billion years ago
or two billion years ago
that these might have been caused by
relatively local gamma ray bursts
the theory is that these might hit earth
on the order of once every billion years
and if you think about the galaxy as a whole
we're kind of in..
our solar system is orbiting the galaxy
its kind of a nice distance from the center of the galaxy
the closer you get into the center
the higher densities of stars you have
so you can imagine if earth gets hit with
one of these gamma rays bursts
every couple of billion years
you can imagine something closer the center of the galaxy
gets hit with these gamma ray bursts
much much much more frequently
just because there is more activity there
there are more stars that are closer by
more stars that are aging
more stars that might be collapsing into black holes
so the simple answer is we don't know
there could be a thousand civilizations out there
and we're not sophisticated enough to notice them just yet
or there might be very very few
because all of this craziness that happens
in the galaxy
or who knows there might be none
although I find that kind of...
that's not too exciting
so I try not to think about that one