look around you
where are you
where is this place you're occupying
somewhere in a room maybe in a city on a
continent on a planet orbiting a star in
a galaxy among billions
but where is all of that while this may
feel like a daft question it turns out
that the concept of an absolute position
is something humans made up
in a nutshell the universe is a big bag
of space that has things in it
if someone removed all these things the
stars and planets and black holes and
dust there would just be empty space
left
in empty space the concept of having a
position loses all meaning empty space
is uniform the same everywhere
the space we occupy is not like a stage
under our feet
we can't mark specific points or staple
something to space-time as an anchor
without things there is no position
we are really ever only at a position in
relation to something else
which also means that things we take for
granted like up and down are actually
relative to
okay let's fill the universe up with
things again and try to find out where
you are right now relative to everything
else
[Music]
let's start this video at a familiar
place and then get increasingly weird
from your perspective the world is
seemingly flat and you can move in three
dimensions it's what physicists call a
frame of reference the perspective you
have of the universe and how you see
things moving around you where your up
and down is
your frame of reference is correct for
you
but not for the rest of the universe
around five kilometers from you where
the horizon begins the ground noticeably
curves away from you
if you could see through the ground
you'd see people from below or sideways
but they don't fall down off the planet
because gravity doesn't actually pull
them down
down is an illusion of your reference
frame to earth's reference frame gravity
just pulls in
but for humans there is an up and down
because within our frame of reference
that just makes sense which is also why
we think that the planet itself has an
up and down north and south and we made
our maps accordingly
but an observer looking at the solar
system might disagree
our maps make sense to us because we're
used to them not because they are
correct
okay so this is step one your position
on what feels like a flat surface but is
actually a sphere
but this sphere is always moving never
staying in one position
earth is orbiting a star the sun at the
center of the solar system
while we usually imagine this is pretty
orderly someone looking at us from the
outside would see something pretty messy
to see this more clearly we'll
exaggerate all these movements this is
not to scale
first of all our orbit really is an
ellipse so we spend half the year
sinking a little bit closer to the sun
speeding up and half the year rising up
a bit and slowing down
and the ellipse itself changes its shape
every 100 000 years too
and in another cycle of 112 000 years
the ellipse itself is drifting which at
least creates a beautiful shape
in the end we get an orbital path that
looks like a wobbly circle with wavy
edges and it gets worse as the moon now
starts to mess things up too
as the moon is a pretty massive thing it
pulls on earth both objects orbit their
common center of gravity that lies
around 4 700 kilometers off to the side
of earth's core
in practice this means that as the moon
orbits earth it's jerking earth around a
bit enough to make it jiggle
okay so you're standing on the surface
of a rotating planet that is jiggling
around the sun in an elliptical orbit
that changes a bit every year but who's
to say the earth is right
from the perspective of the sun the
plane of the solar system is arbitrary
it's defined as the plane the earth
orbits in because that is convenient for
us
in reality the other planets are just a
little bit inclined with respect to our
plane from their point of view we're the
ones with a slightly bent orbit
but this isn't it far from it
the solar system as a whole is orbiting
the center of the milky way galaxy
if we look at the milky way we can
clearly make out a galactic plane in
which the solar system orbits the center
every 230 million years but of course
it's not that simple
first of all the plane of the solar
system is not aligned with the plane of
the galaxy nothing really is just like
the planets in the solar system orbit
the sun on their own planes so do all
the stars orbiting the galactic center
the solar system as a whole is tilted
about 60 degrees towards the galactic
plane speeding through space at almost a
million kilometers per hour
someone in the center of the galaxy
would see the orbits of the planets
moving through space in a helix shape
which you can imagine as a corkscrew
motion on the tilted plane of the solar
system relative to the plane of the
galaxy
this orientation in space means that
sometimes the planets are sort of in
front of the sun as it orbits around the
galactic core
let's just look at this for a moment
there is a strange and eerie beauty
about how our planets and the sun move
through space
do you feel a bit dizzy it gets worse
this is still not the whole story
because the mass of the galactic disk is
constantly pulling on the solar system
too
like a drunk dolphin we're diving down
and shooting up hundreds of light years
through the galactic plane ten times
every orbit along arcs thousands of
light years long
we haven't mapped this motion out
completely as it takes the solar system
tens of millions of years to go up and
back once and well humanity is not that
old
let's look at your relative position
again on a planet tilted towards the sun
jiggled around by the moon in a solar
system tilted towards the galactic plane
moving forward in a helical shape diving
up and down through the plane
but where is up in a galaxy
at this point the frame of reference
becomes a bit arbitrary and pointless
because of the nature of the universe at
this scale
the milky way is part of a galaxy group
that appears to be part of greater
structures like the laniakea
supercluster which itself is part of the
gigantic pisces cetus supercluster
complex and finally a galactic filament
that spans hundreds of millions of light
years in all directions and orientations
someone looking right at us from that
far away will only see the end of
greatness
all stuff appears homogeneous the same
everywhere just like with empty space
when everything looks the same who's to
say anyone's view is better than anyone
else's
we've reached the end of our little
exercise in cosmic humidity
let's make the journey backwards again
from the indescribably large to the
really large to our galactic home to our
galaxy to the solar system diving up and
down through the milky way to the jiggle
of existence and finally back to you
right now watching this video
if this is all a bit much don't feel bad
the scale of the universe is brain
crushing and trying to keep track of how
everything is oriented or decide where
the best up and down is is hard but it
doesn't really matter because it doesn't
change where you are you're already in
the best spot you possibly could be
right here right now
for all you care nothing can stop you
from being right at the center of your
own little universe
perspective really is everything
that's true for the universe we all
inhabit but even more so within your
personal universe
the way your life will unfold also
depends on what you consider possible
take us at kotsgart our passion is to
spark curiosity for science and make
videos for free
but this is not a great business model
so we began to create our own lines of
science posters calendars and fun kotsuk
merch pieces of quotes that you can take
home and touch
and we're doing this with shopify who
are also so kind as to sponsor this
video which delighted us because we've
been using their platform for years now
shopify is an e-commerce platform that
allows you to start and grow your
business and by starting a business we
really do mean from scratch if you want
to sell your handmade ceramic mugs out
of your bedroom today you can but not
just that if you want to scale your
one-man show to a sizeable team then
shopify has the tools to support you on
your journey
now you just have to get started go to
shopify.com
kotzkazak to get a free 14-day trial if
you think that this idea doesn't apply
to you and your ideas are too small we
want to encourage you to think again the
first video on this channel was a
university project and kotskazakt itself
was a creative outlet eventually we grow
into a business and the team that is
making videos for you today and all of
that just because we wanted to try out
something new
this is exactly the sort of thing that
shopify is determined to support and you
can build your own thing with it after
all whether your idea is still just a
dream or might turn into a plan today is
also just a matter of perspective
millions of businesses in over 175
countries are currently using shopify to
sell their products and we are one of
them
thanks to them for helping us get here
and thanks to all of you for making our
channel possible
[Music]
you