hey Vsauce Michael here our atmosphere
is a thin veil of air held to Earth's
surface by gravity we live in it we
breathe it we walk through it every day
it contains all weather but yet it is
almost nothing in fact if the earth was
the size of an apple our atmosphere from
the ground all the way to outer space
would only be about as thick as the skin
of an apple and because our atmosphere
gets thinner exponentially as you go up
90% of our atmospheres mass at this
scale could fit within a space as thin
as just a third of an apples skin but
that shrimpy sliver of appeal would
still be thousands of times thicker than
you are tall we humans are itsy-bitsy
dots strolling around in a skinny sky
but that skinny sky does a lot think
about this what if I had a really
awesome big straw and I stuck one end in
the ocean and the other end out in space
would outer space be able to suck all
the water out we know that naked exposed
the near vacuum of space all non
concealed gases in your body would be
violently farted and burped out sucked
out but sucking is not attractive
instead sucking merely refers to a flow
from a region of higher pressure to a
region of lower pressure in other words
a vacuum cleaner in and of itself does
not attract matter to itself like I said
in my video with no title if you were to
turn on a vacuum cleaner at sea level a
region inside the cleaner becomes as
thin as air in Denver Colorado external
air which is at a greater pressure is
then literally pushed by its own greater
pressure into the machine bringing dust
and debris with it
the point is the strength of the force
pushing air into a vacuum cleaner can
only be as strong as the pressure of the
surrounding air here on earth using a
vacuum cleaner or even a space straw
that pressure is atmospheric pressure at
sea level about 15 pounds per square
inch or 65.4 Newtons that amount of
force can only push pure water up about
ten point three meters or 33.9 feet
because outer space is not ten meters up
it's more like 100,000 meters up a space
straw would be a terrible doomsday
device for a supervillain to use to get
rid of our oceans our atmosphere just
isn't heavy or strong enough to push
water into orbit because the weight of
air above pushing molecules below in all
directions is responsible for air
pressure air lower down exerts more
pressure the air at your feet pushes
with a slightly greater force than the
air at your head now across the human
body you can't tell the difference but
if an object is light enough it can be
affected by this difference which is why
a helium balloon floats the air down
here pushes a tiny bit more strongly
than the air up here and since the
balloon is lighter than the same volume
of air its literally pushed up by the
air more strongly than gravity pulls it
down this upward force caused by a
surrounding fluid or gas that
counteracts an object's weight is known
as buoyancy now here on the surface of
Earth the buoyancy of air isn't enough
to cause humans to float away or be
lifted but it exists in fact in a
perfect vacuum you would weigh about a
fifth of a pound more than you do right
now
thanks air back to our balloon friend
he's not going to float up forever in
outer space
escaping earth eventually as the
atmosphere thins out and the balloon
expands
it will pop and fall back down to earth
it's helium spreading throughout the
atmosphere
so besides rockets that we intentionally
launch off of Earth does our atmosphere
ever lose anything does Earth ever lose
anything does Earth ever gain anything I
mean I used to be smaller I used to be a
little kid but all of the atoms and
molecules in my body right now simply
came from things that I consumed things
that I ate or drank or breathed in when
new kids are born the earth doesn't get
heavier because a new baby is just a
rearrangement of atoms and molecules
that used to be inside its mother or
molecules that she ate drank or breathed
in all of which came from Earth
everything's recycled so is the earth
not gaining or losing mass well to begin
earth does lose some stuff for instance
hydrogen and helium are a bit too light
to stick around because of Earth's
gravity
they eventually fly out into space or
get picked off by solar wind at the edge
of our atmosphere which is why as I've
said before we are likely to one day run
out of helium pretty soon but the earth
gains mass in some ways as well for
instance every year it's been estimated
that 10 to 20 million kilograms of space
dust and meteorite fragments fall to
earth making it heavier now if you
factor in the energy that the earth
radiates away which is equivalent to
mass as well as the energy the earth
gets from the Sun and pulled Zahn to for
instance using its greenhouse gases in
total it has been calculated that every
year earth becomes 50 million kilograms
lighter that might sound like a lot but
it is only zero point zero zero zero
zero zero zero zero zero zero zero zero
zero zero zero one percent of Earth's
total mass which means that for all
intents and purposes the stuff that we
are made of the atoms and molecules in
our bodies the food that we eat the
water that we drink our best friends
has all been here since the early days
of Earth including the air that you are
breathing right now remember that six
trillion kilograms of oxygen that all
humans inhale every year well each and
every one of us individually contributes
by breathing about eight and a half
million times per year here's the thing
about a breath because molecules are so
frustratingly small a single little
breath contains about 10 sextillion
molecules in a poetic twist of symmetry
Earth's entire atmosphere contains a
volume of air equal to about 10
sextillion breaths the number of
molecules in one breath is equal to the
number of breaths our earth has to give
us that is assuming of course that we
never exhaled anything and it never got
renewed which it does and because our
atmosphere gets circulated so quickly
and because we breathe so often and
because molecules are so small
statistically speaking our atmosphere
our skinny little peel of air is crowded
with molecules that we have all had
inside our bodies and been breathing to
make this really mind-blowing let's
focus only on carbon dioxide we don't
just breathe it in and then right back
out again it's a waste product that
comes from all over our bodies and
carbon dioxide is useful to plants which
absorb it and then turn it into sugars
it doesn't just inertly float around our
atmosphere forever okay well it has been
estimated that it takes one breath about
one year to thoroughly mix throughout
the hemispheres of Earth and about 10
years to thoroughly mix within the
troposphere that we live in and a
stratosphere above now given that only
5% of what we exhale is carbon dioxide
and only 20% of that came from
metabolism within our brain
even if we assume that 99.99999 percent
of all the co2 you have ever exhaled has
been trapped in the oceans or absorbed
by plants and made into sugars it is
still mathematically certain even if you
were in a brand new place you've never
breathed in before that every breath you
take contains at least a few molecules
that were once inside your brain a few
of them may have been molecules that you
used five years ago to remember where
you left your keys a few of them may
have been inside your brain when you
first fell in love and a few of them
almost certainly were inside the brain
of your mother while she was giving
birth to you so take a deep breath
because our air is crowded with history
and keep reading because within the next
ten years it is certain that I will
breathe in a few carbon dioxide
molecules that are inside your brain
right now as you listen to me say that
as always thanks for watching
[Music]
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