this video is made possible by simple
contacts get $20 off your contacts by
clicking the link in the description or
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checkout the limits of human vision is
an interesting thing if you're fortunate
enough to have 20/20 eyesight it means
that you can clearly read a small row of
text from 20 feet away but the best
recorded vision in humans is 2010
eyesight which means that these
extremely lucky people can see things
clearly at 20 feet away as if they were
only ten feet away for the normal person
everybody sees the world a little bit
differently than everybody else does and
I mean that literally
not only in terms of clarity or
blurriness but also in terms of just how
much can be viewed if we took you right
now and placed you in the middle of the
ocean on a clear day with nothing to
obstruct your view you'd probably be
able to see in every direction for
around five kilometres but that can
change depending on your height the
limit to your own personal visibility of
the world is determined by two things
the curvature of the Earth's surface and
how high up your eyes are that are doing
the viewing that's because the higher up
your eyes are the more of the earth's
surface you can see before it curves
away from you the average American male
is five feet nine and a half inches tall
which allows a visible range of about
three miles in every direction from sea
level the average American woman is five
feet four inches tall though which puts
a slight negative modifier on their
viewing range so it becomes about 2.8
miles that's not a huge variation but
radical height differences can cause
that at seven foot one Shaq has a higher
visible range of 3.3 miles and Verne
Taylor had only two feet 8 inches had a
visible range limited to only two miles
however Robert Pershing Wadlow the
tallest human to have ever existed at 8
feet 11 inches tall had a massive visual
range of 3.7 miles probably the farthest
of any human who has ever lived if all
of these people were standing on a flat
boat in the middle of the ocean Robert
would be able to see another boat
emerging from the horizon 1.7 miles
further out than Verne Taylor could
possibly see it but of course you can
actually see things further away than
just a few miles you only need to get
your eyes further up into the sky one of
the tallest observation decks anywhere
in the world is inside the Burj Khalifa
in Dubai at 555 metres up from all the
way up here
your line of sight extends out to 84
kilometers in addition into whatever you
can see based on your personal height
this is so high up that it becomes
possible to see the coast of Iran all
the way across the Persian Gulf under
optimal conditions it's also so high up
that it causes some other weird
situations up on the higher levels
becomes possible to see the Sun setting
several minutes after it's already set
on the surface once again because of the
Earth's curvature in your viewing
perception from so high up allows you to
see further around that curvature this
has led some local Islamic clerics in
Dubai to rule that those living above
the 80th floor in the building should
wait two additional minutes before
breaking their Ramadan fast and those
living above the 150th floor should wait
three additional minutes to give the Sun
more time to actually set for them in
fact being near the Burj Khalifa
actually allows you to witness the
sunset twice in the same day
I don't know what that means for Ramadan
so let me know in the comments but
essentially you could watch the sunset
happen on the surface and then take the
elevator up to the observation deck
which is fast enough that you could get
all the way up to the top and witness
the sunset happen all over again
similarly to buildings being high upon
mountains or Hills can also increase how
far away you can actually see something
on the Earth's surface in theory
standing atop the summit of Mount
Everest should give the largest field of
view anywhere in the world out up to 340
kilometers in every direction
if Mount Everest was in the middle of
Germany that would give you the ability
to see over roughly the entire country
but Everest is kind of surrounded by
other mountains which spoils the view
the longest line-of-sight that anybody
can achieve on earth is by standing atop
a summit of don Cova in kyrgyzstan and
gazing a ludicrous 538 kilometres away
to the hindu tog mountain pass in China
this is only possible to see under the
right weather circumstances but nowhere
else on the planet is it possible to see
something else with your naked eyes
that's over 500 kilometres away for
reference that would be like standing in
New York City and being able to see
Toronto we're standing in Los Angeles
and being able to see Sacramento or for
a European comparison standing in London
and being able to see either Edinburgh
or Cologne in Germany but so far we've
only been talking about how far away you
can see something on
surface your eyes can see things that
are much much further away when you turn
them upwards towards space most of the
stars in the night sky that you can see
are located within a few thousand
light-years away from you a Lightyear
meaning the distance that light travels
within one year
the furthest single object that your
naked eye can see while on earth is V
762 casts in the Cassiopeia
constellation at sixteen thousand three
hundred and eight light years away but
much further away than that is the
Andromeda galaxy a collection of objects
which represents the farthest possible
limit of your own naked eyesight into
the cosmos Andromeda is faintly visible
without the need for a telescope at a
massive distance of approximately 2.5
million light years away for most of
human history this served as the
furthest limit for our vision and
perception of the universe until the
advancement of telescopes now we can see
things that our ancestors never could
have liked the galaxy GN Z 11 at 32
billion light years away from us
somewhat confusingly you may remember
from previous videos that I've made that
the universe itself is only about 13.8
billion years old the reason that GN z
11 is 32 billion light years away is
that it probably doesn't exist anymore
it's so far away from us that we're
witnessing what it looked like thirteen
point four billion years ago because
that's how long it's taken the light to
reach us for us to observe it here on
earth but this galaxy probably isn't at
the edge of the universe it's just
impossible for us right now to see
anything that's probably beyond it the
universe is expanding quicker than the
speed of light can move to catch up with
it which means that the light of objects
more distant than GN z11 will never
reach us here on earth which means that
we'll never be able to see what lies
beyond this problem will become worse
and worse as time goes on though as the
universe continues to expand eventually
sometime between four and six billion
years from now the only objects in the
night sky that will remain visible on
earth if it's still exist by then will
be our own small local cluster of
galaxies the universe as we know it
today that's filled with trillions of
galaxies will be totally invisible and
unknowable to civilizations of the
future which means that they may
mistakenly think that the universe is
much smaller than it actually is but we
may think that ourselves a
billion years ago it was probably
possible to see even more galaxies than
we can currently see today since the
universe hadn't expanded quite as much
there is no telling what lies beyond the
limit of what we can see in the universe
and we'll probably never know it's a
serious and unsolvable problem that will
permanently affect humanity's collective
vision but back on earth your own
personal vision problems can actually be
solved and solved easily my normal
eyesight is naturally 2080 which means
that without any correction I see things
that are only 20 feet away as if they
were actually 80 feet away for a normal
person's eyesight and so I've been
wearing contacts since I was 12 years
old in order to see clearly if you wear
contact lenses to but you find yourself
dreading your annual appointment to
renew your prescription just like I
always have you should know that simple
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they have some of the best prices on
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best of all you can get $20 off your
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checkout it's important to mention
though that this isn't a replacement for
your periodic full eye health exam you
still need those but this is the most
convenient way that I've seen to renew a
prescription and reorder your contacts
if your vision hasn't changed so once
again help support real life law by
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watching