hard skull manly here now I love the
Star Wars movies when I first saw Star
Wars as a full year-old it pretty much
framed my life and sent me off in my
spaceship obsessed course in life now
Star Wars movies are actually pretty
light in terms of physics and science
they're often misclassified as science
fiction when I prefer to call them
high-tech fantasy but there's one very
important question for which we can
invoke real-life physics just what kind
of power does it take to destroy a
planet I mean three of the seven movies
involve devices that are able to destroy
planets and I should mention that
there's a couple of minor spoilers here
and as it turns out it's pretty easy to
figure out how much energy it would
actually take to destroy a planet
indeed in 2001 a paper addressed this
issue by calculating the gravitational
binding energy of the spherical planet
you know physicists love approximating
things to spheres by the way at least
with planets that's closer to reality
anyway the gravitational binding energy
is a pretty simple concept for any
Kerbal space program player
we know that the escape velocity is the
critical speed above which an object
will escape to infinity and never fall
back now imagine that you grab a rock
from the surface of the planet and shoot
off at escape velocity it's an easy
equation to figure out how much energy
is required now repeat that bit by bit
rock by rock as you go on you're
actually going to need slightly less
energy because as you throw bits into
space there's less mass of the planet
left behind to hold them down but anyway
if you add them all up using calculus
you get a very simple equation the
energy is 3/5 times the gravitational
constant times the mass of the planet
squared and divided by the radius of
plant of the planet now for Earth that
number is about 2.2 5 times 10 to the 32
joules or in iliyan speak 225 million
trillion trillion joules however in the
same paper they went on to calculate the
for larger planets like Jupiter the
energy would be even higher something
like 2 times 10 to the 36 joules that's
at 2 trillion trillion trillion joules
the authors hypothesize that the death
star may in fact be able to
destroy this by shutting down some of
its non-critical systems like
life-support and it wouldn't put that
past the empire given our spotty record
on providing basic workplace safety
features like handrails now this paper
is actually under estimating the power
of this technological terror and by
extension the power of the force in Star
Wars we see the destruction of Alderaan
in but a few seconds the planet explodes
sending fragments away but assuming that
Alderaan is similar to the earth that
exploding ball of plasma is exploding at
many times the escape velocity look at
this demo in universe sandbox to show
just how slow escape velocity is when
you're comparing it to the size of the
earth it's not particularly dramatic
unless of course you're on the surface
of that planet this is of course done
because Star Wars is a movie and the
audience expects special effects to wear
them rather than bore them if we
re-examine the sequence in slow-mo we
can see that within a second the ball of
pulverized planet is about two to three
times the size of the original planet so
substantial part is moving at over
10,000 kilometers per second we're
dealing with velocities many times
higher than the escape velocity and the
gravitational binding energy is really a
small correction compared to the kinetic
energy required to accelerate a planets
worth of mass up to these speeds to be
fair this is an explosion and it's more
like a range of velocities but even if
we take say a baseline of 1,000
kilometers per second the energy
required to obliterate Alderaan in this
manner that will satisfy moviegoers is
about three times 10 to the 36 joules
are once again three trillion trillion
trillion joules now in the force awakens
we have a new generation of planet
busting super weapon that can project
its beam of destruction over
interstellar distances and destroy
entire solar systems but moreover it's
powered by a star which gives me another
opportunity to invoke real physics our
Sun emits roughly 3.8 5 times 10 to the
26 watts of power or again in iliyan
speak 385 trillion trillion joules per
second which means that for early
and estimate it would take about a week
of the sun's energy output to obliterate
Alderaan or 250 years if you look at my
higher estimate now I'm gonna ten
billion year lifespan of a star that
isn't so bad but I do have some
straight-up problems with this maybe I
missed it but it seems to me that they
weren't planning on moving Starkiller
base around after all the energy
required to move a planned it into
hyperspace is probably similar to the
energy required to destroy a planet by
moving its different pieces at several
kilometers per second in different
directions but if you had to consume the
entire star to do that then you would
need another star and if you can't move
where you're gonna get another star it
seems like bad planning I mean you don't
even need mathematics to figure this out
okay look scriptwriters Hollow
look there is a way to fix this there
are stars that have luminosities that
are something like a million times
higher than the Sun they're short-lived
but they can generate the energy
required for epic planet busting for
millions of years long enough for any
movie franchise star killer base could
soak up all the power at one to two from
the outer layers of these stars it could
they even make the star turn from blue
through red to black as the energy was
siphoned off giving those x-wing pilots
a way to gauge how long they had left in
a visually arresting style and then of
course after the siphoning stopped the
star would return to normal energy
output and be ready for firing again in
a few days time of course the script
writers never asked me regardless if you
really want to go into planetary
destruction to strike fear into the
hearts of your enemies the Empire and
the first orders are going way overboard
making millions of voices cry out in
terror just requires obliterating the
top put your point one percent of the
planet near the surface the other 99.9
percent of a planet is generally things
like magma that isn't particularly
hospitable to life
I'm Scott Manley fly safe
you