Kind: captions
Language: en
there is this famous Google interview
question that everyone gets wrong you're
shrunk down to the size of a nickel and
put into a blender the blades will start
spinning in 60 seconds so what do you do
I would like to think I could duck down
and miss the blades break the thing at
the bottom maybe push
the ask nicely for the blender not to be
turned on time my clothes together and
then like use it as a rope I guess if I
was lighter I could maybe catch a draft
up except defeat I mean I'm the size of
a nickel what quality of life is that
okay resonance I'm going to run to one
wall push on it run to the other wall
push on it run to the other wall so I'm
going to tip the container over honestly
the thing I would think about is trying
to get to the very center of the blades
it's spinning around me but the actual
RPM is probably not that high if I'm
standing in the middle I tie my clothes
to one of the tips of the blades as it's
starting up yeah I get it to swing me
around and then
I but these answers don't cut
it now I first heard about this problem
in this book it describes how each year
Google received about 3 million
applications but they would only hire
7,000 people that's a 2% acceptance rate
so one way to screen out millions of
applicants was to use brain teasers and
the interviewers would make these up for
fun we didn't get a list at that time of
what what questions to ask we would
share questions among each other some of
them gain traction questions like how
many golf balls can fit in a
747 or how much should you charge to
wash all the windows in Seattle but the
blender question really stuck with me
and I'm not alone you just lay back
enjoy that
bre the best model in the world is only
going to run maybe 10 or 11 hours so
we're getting out and when we do we're
better off for it because whatever
doesn't kill you makes you stronger the
question has been hotly debated in
Reddit comment
sections there are so many different
answers but which one is the best try to
hide underneath the blades I guess Hide
Under the Blade probably great first
reaction but maybe that doesn't solve
your problem entirely now you're just
stuck inside of a spinning blender so
maybe you want to escape can I climb the
walls are there defects in the walls
that are sufficiently large for me to
grip onto do I have bander walls forces
that are strong enough to connect me to
the wall am I like essentially a tiny
gecko a gecko can stick to the wall of a
blender even though neither its foot nor
the glass are charged the gecko's foot
has to be pressed firmly against the
glass so its atoms are within a few
nanometers of the glass atoms then at
any moment one atom's electrons aren't
uniformly spread about the nucleus they
might be slightly more on one side than
the other this makes the atom
momentarily slightly positively charged
on one side and slightly negatively
charged on the other the glass atom next
to it experiences the pull of this
charge imbalance and so a similar charge
imbalance is induced on the glass atom
and therefore the electrons in the glass
atom are drawn to the nucleus of the
gecko atom and vice versa so there is a
very weak attractive force between
neutral atoms this is known as a Vander
walls force and it's what makes geckos
stick to walls it's the same force that
holds graphite together there's no
actual bonding between the layers of
graphine and a pencil it's like a stack
of paper the layers only stick because
of Vander wal's
forces now these forces are pretty weak
but since we're so small maybe they'd be
enough to help us climb out this I can
almost certainly say we wouldn't be
sticky at that scale and that's because
the Vander walls type interactions are
still small and I studi claing so that
these cockroach and gecko you know it
turns out that you have to get very
special to do that geckos have millions
of tiny branches on their feet that
increase their surface area and allow
them to mold to surfaces our hands
aren't like that but ants and
cockroaches don't rely on Vander wal's
forces and they can still climb up walls
so maybe a miniature human could too the
mechanism of a cockroach foot and I used
to know all about cockroach feet is
absolutely gorgeous same with a hand by
the way there's two little claws the
inaro claws those are things that slat
down on a surface and really do slap
when their climbing meters a second SWAT
engage despite having no adhesion have
very sophisticated frictional attachment
those claws can grip almost anything
even glass while glass feels smooth to
us it's actually covered in tiny surface
imperfections and at insect scale these
features are significant
ants basically have climbing gear yeah
they're like using little like axes
basically to to pick their way in we
don't have the attachment discs or
whatever that would be or like the the
special claws or the Vander wals forces
we have claws if you're that scale our
fingers are claws we only really got we
have two claws really and then our our
feet aren't great at climbing I don't
know well it again at scale though I
don't know right imagine putting a
little sharp Spike into your foot
sharpen your shoes or high Deal
shoes you'll be good to go so now I'm
climbing in heels but there's still a
problem I mean I'll have to be pretty
careful placing each hand and foot
slowly it's going to take longer than 60
seconds to get out and in that time the
blades will have started spinning one
mistake and I'm a
smoothie so Google was looking for a
different answer all right now we're
going to the physics building maybe they
know yeah I really got
nothing I'm sted this is so embarrassing
we're in like our last year of our
degree we should definitely know this I
feel like I could probably swing running
around the sides and yeting myself out
okay if we're just talking about the
entropy it should increase at some point
so some sort of chaos should be none of
the system will stay undisrupted take
that as a limit to infinity and I I'll
be chilling like using that logic if I
just like extrapolate right no that's
still too big for me to Quantum tunnel
or anything like that whoa whoa whoa
whoa I mean that is really overthinking
it it's actually not that complicated do
you want to hear the best answer I've
heard yet sure just jump just jump how
would that work just jump how how does
that work like that jump where out of
the out of the bu just go up so whoever
told you that is it's crazy right yeah
that makes sense to you no it doesn't
but do you want to hear do you want to
hear why that works yeah tell me how it
works jumping out of a blender seems
impossible because at nickel size theall
of a blender is 15 times your height it'
be like leaping over an 8-story building
but watch these
clips did you notice
it a horse a dog and a squirrel they all
jump to about the same
height this is exactly what Alfonso
burelli the father of biomechanics
looked at in the 17th century
as he put it in the same conditions
smaller and lighter animals make bigger
jumps relative to their body if the
other conditions are equal and indeed
the limbs and the other organs are in
the same proportion the dog will jump as
far as the horse now sure there is
variation a species whose survival
depends on jumping will be optimized for
It While others like turtles and
elephants they don't jump at all but
when you consider the huge variations in
size I mean a horse is500 times heavier
than a squirrel it's incredible that
they jump to around the same height and
it's not because squirrels are super
muscly or something horses and squirrels
have similar muscle to weight
percentages and insects have even less
muscle relative to their weight why do
you think an ant can lift 50 times its
own body
weight like is it any more muscular no
you guys hit the gym come on like you're
not you're more muscular than an ant so
how are small things so strong well if
you look closely at a muscle it's made
up of tiny units called sarir they act
like miniature Springs how far a muscle
compresses depends on how many of these
Springs are in series but the strength
of a muscle depends only on how many are
working in parallel so the thicker the
muscle the more Springs are in parallel
and the greater the strength therefore
strength depends on the cross-section
area of a muscle and as animals shrink
this cross-sectional area scales down
with the square of their height but an
animal's weight is proportional to its
volume so that scales with the cube of
their
height so as you scale down weight
decreases faster than strength and as a
result smaller animals have much higher
strength to weight ratios I mean you
could probably lift uh your own weight
like if you were to put your own body
weight on your back and and squat that
you could now left 100 100 times yeah
let's go and for us stuck in that
blender that extra strength relative to
our weight means we could jump right out
your surface area decreases with the
square mhm you'd be like a little
Superman I see okay that's really cool
so I could jump like literally out of a
blender you could jump out of a blender
but in movies and games where people are
shrunk they almost never show it like
that honey I shrink the kids was one of
my favorite movies when I was a kid
I love that tiny people struggle picking
up scissors they almost get crushed by
raindrops if it was scientifically
accurate they'd actually be overpowered
most people don't think of this when
they first hear the question the answer
almost seems too simple when you ask the
right questions you define the problem
there's some some really obvious
solutions that work and that's actually
true for a lot of problems in the real
world too now I'm all for obvious
Solutions but from the start the answer
of jumping out didn't sit right with me
even this idea of like I'm going to jump
out of the blender like that doesn't
make sense to me because jumping is not
just like okay how strong you are
relative to your weight it's also timing
and your kinetics and all that so like
how long can you be in touch with the
ground how much can you apply that force
in one burst like over a really short
period would it be fair to say you're
overthinking
things you got to suspend your disbelief
somewhere I think if you like factor in
all the potential challenges a human
would have just like if they're just all
of a sudden that size they don't have
like time to practice using their legs
and stuff in that new environment like I
don't give them very good chances of
jumping out sometimes there are people
who make everything more complex than it
needs to be and that that can be
problematic I would like to see like you
know realistic modeling of like we scale
me down 100 times like can I jump higher
like I want to see someone do those
physics equations like yeah you could
jump higher but you could jump 100 times
higher you know so that's why we got the
researchers at Georgia Tech biomechanics
Lab to investigate while they are
figuring that out let me tell you about
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docomo now let's see how that simulation
is coming along okay so we have our
simulated blender we are 2 cm tall and
we have to jump at least 30 cm to get
out I was like well what about me like
I'm pretty you know embarrassingly
nonathletic what if I do this and I did
it right here next to my desk my partner
sort of measure my jump height and I
know how much I weigh and all that stuff
so what would it look like for me if we
have a person that weighs 84 kg is
squatting 15
cm and has a jump height of 27 CM that
person if they were scaled down to 1% of
their original size they would jump 42
CM
High the simple simulation shows a jump
height of 42 CM so you would make it out
but we need to add in air resistance
since our cross-sectional area is now
100 times larger relative to our weight
drag should have a greater effect at
nickel size if it was 42 CM jump height
before for the jumper with drag
considering drag then it it's about 39
CM so we do decrease in Jump height a
little bit but that drag calculation is
assuming you jump perfectly vertically
but what if you're a bit uncoordinated
and you flip onto your side mid jump
well then you're exposing 10 times the
surface area and that increases the
amount of air resistance like if somehow
you flipped and and you were still
moving up like this like what is the air
resistance then so doing that that means
22 cm jump height oh so we don't we
don't uh oh darn if you start getting
overconfident and you wanted to do like
a backflip while you were at it then
you're going to mess it up yeah don't
backflip out of the blender is a good
good piece of don't try and show off
you're trying to not get chopped up just
like just go head first it's not so much
getting out of the blender it's what
happens next you've got two nickel-sized
men free in the world World think of the
possibilities the simulation came back
you can jump out of the freaking
blender all right okay I'm glad we went
through this uh this exercise do you
want me to do another month of research
on this no like you've done you've done
enough you've done enough I'm
convinced I feel like jumping is an
unsatisfactory answer it was
unsatisfactory When you mention it in
the first place and you went through and
you got the simulation you got the model
and you're like look you know our little
guy can jump 40 cm so are you convinced
now and I'm like I
guess but like my Spidey Sense was
tingling oh there something going on
you're telling me that I have to apply a
force in 1 1,000th of a second and I
have to undergo
G's I'm not going to survive that so
what I'm getting now is that like my
intuition was good I think everyone's
intuition who's like you can't jump out
of a blender I think they're right and
you may say well that's overthinking it
but that's the whole point of the brain
teaser is to overthink it is to get to
that point where you're thinking about
it in the detail of like what would
actually be feasible a whole lot of
things would go wrong our hearts have to
generate a certain amount of pressure to
get the blood you know going up to our
head and going all the way down if you
take the human heart and shrink it down
it's not going to be able to generate
the same kinds of forces I think there
would be a catastrophe uh at a smaller
size controlling air pressure inside
these countless sacks inside of of our
lungs there's an Exquisite balance there
now you you try to take that same design
and and squeeze it down I would be
skeptical that you'd be able to keep the
passageways open you wouldn't even be
able to think this through cuz you just
wouldn't have the brain structures that
we have you can't fit 86 billion neurons
in a nickel sized volume you can't scale
cells down either that's the thing like
cells are cells I mean jumping out would
be to me seems like your only option but
I don't think you're going to be able to
jump because you can't breathe and your
heart can't pump blood so you just kill
over and die before you can make your
jump okay so if you're a biologist you
think we'd die if you're a physicist you
can decide whether we'd little Superman
or as I believe incapable of fully
harnessing our extra strength what did
belli know he didn't even have
blenders he doesn't know the stress but
if you're an interviewer at Google you
might not even care what the answer is I
think one of the misconceptions that
candidates have is when I'm asked this
question it's because they want to see
if I can solve this problem that's
actually not quite right there are five
attributes people are looking for
there's addressing ambiguity there's
breaking down the problem being creative
being smart and then communication so I
guess like none of those five are
whether it's correct right we're the
idiots who went and tried to figure out
what's the best of those answers so um
yes Google realized that asking these
types of questions didn't make much
sense llo Bach the senior vice president
of people operations at Google said this
on the hiring side we found that brain
teasers are a complete waste of time how
many golf balls can you fit into an
airplane how many gas stations are in
Manhattan a complete waste of time they
don't predict anything they serve
primarily to make the interviewer feel
smart but I just feel like there's that
moment where you're like so are you
going to admit you're wrong and I'm like
yeah you know I think this is further to
like I'm not wrong this is crazy this
question is crazy and I think it goes to
your very Point your very point which is
that like brain teasers like this are
not good ways to assess whether people
know what they're talking about so
although brain teasers aren't useful to
assess job applicants they are useful
for something I mean every time we ask
this question to people on the street to
physics students and to scientists they
lit up they had to try to see the world
from A New Perspective and it's exactly
this way of thinking that has led to
some of the biggest scientific
discoveries Einstein used thought
experiments to come up with his theory
of relativity Oilers solution to the
bridges of Kingsburg puzzle is what
inspired graph Theory and when schinger
wanted to illustrate his problems with
quantum mechanics he imagined a cat in a
torture box the blender question is
admittedly silly but silly questions can
yield profound answers and show us new
things I think in order to learn
something new you have to be willing to
embrace the ridiculous and Just Go With
It
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