Austrian physicist Erwin Schrodinger is
one of the founders of quantum mechanics
but he's most famous for something he
never actually did a thought experiment
involving a cat he imagined
taking a cat and placing it in a sealed
box with a device that had a 50% chance
of killing the cat in the next hour at
the end of that hour he asked what is
the state of the cat common sense
suggests that the cat is either alive or
dead but Schrodinger pointed out that
according to quantum physics at the
instant before the box is opened the cat
is equal parts alive and dead at the
same time it's only when the box is
opened that we see a single definite
state until then the cat is a blur of
probability half one thing and half the
other this seems absurd which was
Schrodinger's point he found quantum
physics so philosophically disturbing
that he abandoned the theory he had
helped make and turned to writing about
biology as absurd as it may seem though
Schrodinger's cat is very real in fact
it's essential if it weren't possible
for quantum objects to be in two states
at once the computer you're using to
watch this couldn't exist the quantum
phenomenon of superposition is a
consequence of the dual particle and
wave nature of everything in order for
an object to have a wavelength it must
extend over some region of space which
means it occupies many positions at the
same time the wavelength of an object
limited to a small region of space can't
be perfectly defined though so it exists
in many different wavelengths at the
same time we don't see these wave
properties for everyday objects because
the wavelength decreases as the momentum
increases and a cat is relatively big
and heavy if we took a single atom and
blew it up to the size of the solar
system the wavelength of a cat running
from a physicist would be as small as an
atom within that solar system
that's far too small to detect so we'll
never see wave behavior from a cat a
tiny particle like an electron though
can show dramatic evidence of its dual
nature if we shoot electrons one at a
time at a set of two narrow slits cut in
a barrier
each electron on the far side is
detected at a single place at a specific
instant like a particle but if you
repeat this experiment many times
keeping track of all the individual
detections you'll see them trace out a
pattern that's characteristic of wave
behavior a set of stripes regions with
many electrons separated by regions
where there are none at all
block one of the slits and the stripes
go away this shows that the pattern is a
result of each electron going through
both slits at the same time a single
electron isn't choosing to go left or
right but left and right simultaneously
this superposition of states also leads
to modern technology an electron near
the nucleus of an atom exists in a
spread out wave-like orbit bring two
atoms close together and the electrons
don't need to choose just one atom but
are shared between them this is how some
chemical bonds form an electron in a
molecule isn't on just atom a or atom B
but a plus B as you add more atoms the
electrons spread out more shared between
vast numbers of atoms at the same time
the electrons in a solid aren't bound to
a particular atom but shared among all
of them extending over a large range of
space this gigantic superposition of
states determines the ways electrons
move through the material whether it's a
conductor or an insulator or a semi
conductor understanding how electrons
are shared among atoms allows us to
precisely control the properties of
semiconductor materials like silicon
combining different semiconductors in
the right way allows us to make
transistors on a tiny scale millions on
a single computer chip those chips and
they're spread out electrons power the
computer you're using to watch this
video an old joke says that the internet
exists to allow the sharing of cat
videos at a very deep level though the
internet owes its existence to an
Austrian physicist and his imaginary cat
you