Kind: captions
Language: en
uh we are driving to a very strange
location somewhere I have never been and
it's because of the woman in the back
seat this is Diana physics
girl yeah uh we're we're going to go uh
get a consultation for something very
special right now it is look I'm not
going to keep you in suspense laser hair
removal we want to talk about the
science that makes laser hair removal
work I told him about this idea last
like probably a year ago and and then I
was going to do it in July or August and
I've been waiting for this moment Dar so
now I'm scared now you're scared here we
go oh
yes it stinks oh man it went directly
into your nose it's called laser plume
laser plume that's the smoke that comes
off the smoke yeah how was that shot
[Music]
the laser we're using has a wavelength
of 1,64 NM meaning it is infrared
radiation invisible to the naked
eye but without an infrared filter the
camera sensor picks up the laser pulses
which in my case were six at a Time Each
one lasting about 1 and 1/2 milliseconds
we dialed it up a little we dialed it up
just to nice ready the laser will now
deliver 25 Jew of energy per square cm
that was beautiful oh wow that might be
a really good shot now we're talking oh
my God all right so you're going to want
to watch this one wo oh my God that is
insane there's five bursts did you see
that yeah it looks like like a shootout
of the okay Corral that's what that
looks like it does all the hairs are
just getting like slaughtered that is
amazing that is an awesome shot W that's
sick that's really
[Music]
sick I have no idea that it was a
shootout at the okay crow that makes me
really it kind of reignites my
excitement about my job so that's
awesome I'm going to get even closer on
this next one that' be cool
[Music]
[Applause]
so what's actually going on here well
dark eyes skin and hair contain a
molecule called melanin and melanin
absorbs a wide range of wavelengths of
light especially in the ultraviolet part
of the spectrum and this makes it an
ideal Shield against the sun's harmful
rays which is why you get a tan when you
go out in the sun that's your body
producing and releasing more melanin in
the skin but the idea with laser hair
removal is to get the melanin in dark
hair is to absorb the laser light
without the skin around it absorbing
much of that energy so it actually works
best if you have really dark hairs and
light skin infrared lasers are commonly
used because melanin absorbs in this
part of the spectrum more than other
common molecules in the skin like water
and oxyhemoglobin red lasers at 755 nanm
are also often used for the same reason
as the melanin absorbs the laser energy
the hair heats up to well over 100°
celius causing it to burn and vaporizing
the water it contains and this Puffs the
hair up a little bit like a Cheeto it's
that expanding water vapor looking
closely at this shot you can actually
see the bubbles on the hair from the
vaporization of water
but the objective is not to destroy the
hair it's to actually use the hair to
destroy the germ cells in the follicle
that produce the hair in the first place
so it's kind of like using the hair to
kill the hair this image shows a
cross-section of three hair follicles
following a laser hair removal treatment
and the one in the middle contained
little melanin and therefore shows no
damage the other two show the hair shaft
has been destroyed rupturing the inner
root sheath and damaging the outer root
sheath cells suffer damage when their
temperature rises above 60° C this is
because at that temperature the bonds in
proteins and collagen molecules start
breaking apart and that's a process
known as denaturation so the hotter it
is and the longer that temperature is
maintained the more denaturation occurs
and the higher the likelihood that that
cell will die now if you cause enough
damage to the cells in the follicle that
make the hair the hair will never grow
back and that is the goal of laser hair
removal the sequence of ultra short
pulses is used to ensure that the heat
doesn't spread too far into the region
surrounding the hair so the idea is the
hair heats up damages The Germ cells
right next to it but then the laser
light turns off before that heat can
spread too much further and then you hit
the hair with another very short pulse
again if you were instead just to keep
heating the hair it would heat not only
the germ cells around it but also your
skin that you don't want to damage and
you would end up with Burns so that's
the reason for the series of pulses that
we saw but if you think about it this is
kind of a weird irony I mean melanin is
a molecule meant to protect us meant to
protect our skin from harsh rays of
sunlight and that's why it absorbs that
light before it can penetrate further
into your body and do damage but now
with laser hair removal we're using
melanin its unique absorption Powers
against it by overpowering it with lots
of laser energy we get it to heat up the
hair to such high temperatures that the
hair kills the neighboring cells The
Germ cells and the folc that produce the
hair so we are are using melanin's
powers against it normally before a
laser hair removal procedure the hair is
shaved and that serves a few purposes
for one thing not too much energy goes
into burning the external hair which
does you know good in the first place
and second it prevents the hot hair from
landing on the skin causing surface
Burns but we found that shave patches
were less interesting to watch because
you can't really see what's happening
under the skin after the creation of the
first working laser in 1960 its invent
theater Manan called it a solution
looking for a problem an unwanted hair
may just be that problem because laser
hair removal is the most requested
cosmetic
procedure hey I have a lot of people to
thank who made this video possible like
Diana physics girl whose idea this was
thanks to her I no longer have that
strange patch of hair on my shoulder so
you should really go check out her
Channel physics girl and I also want to
thank Darren without him at Beyond slow
motion we would never have been able to
do this he was simply amazing so you
should also check out Beyond slow motion
and of course I want to thank audible
the leading audiobook provider with
hundreds of thousands of titles in all
areas of literature including fiction
non-fiction and periodicals whenever I'm
out I'm on the go and I can't really
watch videos like when I'm driving then
I listen to Audible and I also listen to
audible when I'm on the plane and I'm
about to get on a plane right now and
fly to spard Norway which is nearly the
North Pole and that is going to be a
very long flight so I will definitely be
listening to uh my audio books in fact
the audio book I'm listening to at the
moment is called creativity Inc and I am
learning a lot from this book about how
to be a creative person and how to be
productive and it's a great book to
listen to because it's a story told by
Ed catmull and you kind of feel like
he's there with you telling you the
story of how Pixar was founded and how
they made creativity work so I'm loving
that book if you want to check it out
you can actually download it for free or
you get a 30-day trial by going to
audible.com/veritasium you know one of
the reasons audible keeps supporting
veritasium is because they know that the
people who watch this channel like
learning things and another way to learn
things besides YouTube is to listen to
audiobooks so I highly recommend you
give them a try for a 30-day free trial
if you want to do that go to
audible.com/veritasium thank you so much
for watching