Kind: captions
Language: en
[Applause]
do you think there is life beyond the
Earth um yes I do why is that
um scientifically been
proven are we alone or is there life
elsewhere in the universe this is a
question humans have wondered about for
Millennia and one that people still have
pretty strong opinions about even though
there isn't definitive evidence to
answer the question one way or the other
do you think that aliens have ever come
to
Earth um people say that there's like
there's been aliens and they they
implant I forget what it's called but
they've like made um these fields and
they've like produce something on Earth
I think Area 51 could be could be could
be possible could be real you know how
there's Area 51 and all that kind of
stuff I reckon they've got technology
that they not bring it out yet you know
like do you think it's technology that
came from Aliens possibly they could
they could be sharing information and
gaining technology from aliens on
YouTube there seems to be some pretty um
good evidence about it but I don't know
see some videos of aliens that look
convincing kind of yeah so the anunaki
Apparently were um beings that came down
from heaven um according to the old
Sumerian text with the wall paintings
and stuff and and um suaria suia I think
people believe that aliens have visited
us just because they're not aware of how
vast the universe really is I mean what
is an exoplanet how far is a lightyear
these are the things you need to
understand if you're to judge the
probability that alien life could come
and visit us what is a
Galaxy specifically I I wouldn't know is
a Galaxy something totally different
like another Universe maybe a Galaxy as
a sun and a moon doesn't
it so so a a galaxy is bigger than
that um
off galaxies hundreds of stars blah blah
blah in fact hundreds of billions of
stars billions of stars yeah hundreds of
billions yeah yeah what is a Galaxy it's
a collection of stars and gas that are
held together in a gravitationally bound
system every point of light that you see
here is a star when we say 200 billion
stars it's probably at least 200 billion
stars the galaxy is 100,000 light years
across so you know it's just the
distances are imag unimaginable one
light year don't forget is 10 trillion
kilm what's a light year you're an
engineer a light year is a th000 years
isn't it a light year is a th000 years
isn't it about 150 human years would be
a light year would be a light that's
what I believe it would be is a distance
is it a distance a light year have you
heard the term exoplanet no no never
exop Planet no like a planet that we're
not aware of well EXO should could be
short for something
extraterrestrial planet or
extraterrestrial life maybe something
outside our planet so an exoplanet is
simply a planet that orbits a star other
than the sun um EXO just means external
outside so outside our solar system so
it's just a planet um you know you can
how many have you found me personally uh
I've found six but overall we now know
of uh over 800 planets that have been
confirmed and another probably 2
thousand planets that are a waiting
confirmation but are pretty strong
candidates so we don't see the planet uh
directly we see its impact on the star
that orbits we do it from the ground
with the the Anglo Australian telescope
uh and we look for the wobble of the
Star as the planet orbits the planet
goes around and the star moves backwards
and forwards so if you can imagine
seeing that from uh sort of along the
line of sight a little bit more say like
in this in this cartoon here then you
would see the star moving towards you
and moving away from you and so what we
see here is uh the light from the Star
becoming ever so slightly Bluer as it
moves towards us and ever so slightly
redder as it moves away the big problem
is that the main kind of planet you end
up finding with this wobble technique
because it's really reliant on the mass
of the planet uh basically like Jupiter
Saturn and then we've started to get
down to Neptune and Urus to find smaller
planets NASA launched Kepler a 1 M
telescope with a 95 megapixel camera its
mission is to observe 130,000 stars in
our galaxy and look for dips and
brightness caused by planets passing in
front of them so Kepler 62 is a solar
system with five planets and the planets
are very similar in size to the
terrestrial planets the rocky planets in
our own solar system so you have the
star in the middle then you have three
inner planets there's a green band which
is this habitable zone The goldilock
Zone where you can expect liquid water
to exist uh on the surface of the planet
and in fact there are two planets inside
the habitable zone around Kepler 62 if
you're going to start looking for life
around nearby Stars this is probably the
best one to start with is there life
beyond the Earth well we don't know for
sure we can't say yes definitely but the
probability is very high there are at
least 200 billion stars in our galaxy we
now know that on average there is at
least one planet per star in our galaxy
alone and there are another 100 plus
billion galaxies in the universe we also
now thanks to the kep spacecraft that at
least one in six of those is earth size
and so that's 33 billion potential Earth
siiz planets not all of them are going
to be able to have life but the
probability is getting pretty high
already at this stage so there is no
definitive evidence that alien life
exists but the sheer size of the numbers
suggests that they must be out there
somewhere but with the vast distances
Across the Universe chances are it's
going to be a long time before we know
for certain that we are not alone
this video was created as part of a
collaboration addressing 10 unanswered
science questions so subscribe to
veritasium and then check out the other
nine questions by clicking the
link okay is there more than one Galaxy
out
there
uh yeah
probably how many would you
say ah I couldn't tell you it's probably
more than on my 10 in fingers I guess
it's more than 100 billion 100 billion
probably it's crazy yeah