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hey crazies let me tell you light is
crazy fast it travels at 671 million
miles per hour that's a hundred and
eighty six thousand miles per second or
three hundred thousand kilometers per
second or thirty centimeters per
nanosecond whatever units you choose
that's crazy fast fast fast so fast it
might leave you wondering how fast is
that exactly let's do some comparisons
the fastest humans in history were the
Apollo 10 astronauts at point zero zero
six percent the speed of light the
fastest human-made object was the Juno
space probe at point zero two five
percent the speed of light Andromeda is
hurtling toward the Milky Way galaxy at
point zero four percent the speed of
light all of these are tiny fractions of
that 671 million miles per hour
physicists have really only gotten close
to the speed of light with subatomic
particles the record for a proton and
the Large Hadron Collider is 99.999999%
the speed of light now that's fast fast
I'm a mad scientist though we can do
better I have a specially designed
rocket just for this purpose this seems
dangerous I probably shouldn't do this
myself
we'll use Rocket clone alright
we lost him during the twins paradox
video guess I'll have to make another
one
[Music]
all right now we have a rocket clone
let's do this
say he gradually accelerates away from
my space station faster and faster and
faster
how will it take him to reach Lightspeed
well he won't see accelerating arrest
mass like a person or rocket requires
energy for example a rocket transforms
energy from its fuel into kinetic energy
it will continue to accelerate as long
as it burns fuel even if he somehow
managed to turn all of the energy in the
observable universe into kinetic energy
for himself he'd still only be going
99.999 that's a hundred nines after the
decimal place which is still not
honoured percent it would literally take
an infinite amount of energy over an
infinite amount of time to accelerate up
to exactly the speed of light it's
impossible that being said there are
things in this universe that go at
exactly the speed of light namely light
and that's any light from the spectrum
not just visible light but also
gravitational waves and anything else
without rest mass gluons any way that
speed does exist but the fact that it's
impossible for massive objects to reach
it has a weird side effect no matter how
fast you go light will always be faster
671 million miles per hour faster light
is so fast that it breaks our
understanding of how speed works how can
it always be going the same speed faster
than you because space-time
we're gonna need a spacetime diagram if
you're not familiar with those you
should go check out this video first all
right let's bring Rocket clone back for
another experiment if instead of
accelerating he travels at a steady
speed his space-time path will look like
this let's consider the part between my
space station and I don't know Wolf 359
there are about 8 light-years apart and
the trip takes about 14 and a half years
we know speed is space divided by time
so eight light-years divided by 14 and a
half years is 0.55 light or 55% to speed
light we can draw those measurements as
a triangle which makes the speed the
tangent of an angle but not the tangent
you know and love
most people don't love trigonometry
really yes really weird anyway this
isn't a regular tangent it's a
hyperbolic tangent or tange for short
switching from my point of view to raka
clones requires a hyperbolic rotation
don't ever forget relativity rule number
three huh let me just show you these are
my coordinates
these are rocket clones me rocket clone
me rocket clone the space and time axes
rotate in opposite directions to line up
with the observer taking the
measurements that's called a hyperbolic
rotation because the coordinates on each
axis move along hyperbolas the more his
path is tipped from mine
the faster he's moving according to me
so let's look at a bunch of different
speeds and see what happens this is
stationary this is 10% the speed of
light here's 25% 50% 75% 90 99 99.9999
seeing a pattern here they're
approaching this diagonal path even the
accelerated rocket from earlier
approaches it that diagonal is the path
that light would take in space-time at
least if it was traveling the same
direction both this rocket and this
light are traveling to the right if we
sent another set to the left it would
look like this the angles in here are
weird though these two angles give us
55% the speed of light but this angle
only gives us 84 and a half percent not
a hundred and ten percent these two
angles give us exactly the speed of
light and this angle also gives us
exactly the speed of light any angle
measured from those diagonal paths will
give you exactly the speed of light
every single one of these angles gives
us exactly the speed of light that is
some crazy distortion the point is that
a hyperbolic rotation keeps the speed of
light constant the speed of light is
measured to be exactly the same by
everyone no matter what so here's what
we've learned the speed of light is the
up
limit for speed in any direction it's
671 million miles per hour which is
unimaginably fast so fast that no matter
how fast you go light will always be
faster 671 million miles per hour faster
in just in case that hasn't completely
sunk into your brains yet even if you're
going 670 million miles per hour light
is still going 671 million miles per
hour faster than you that's crazy
so how crazy do you think light is let
us know in the comments thanks for
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out to patreon patrons like Ilya Yashin
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show possible
and until next time remember it's okay
to be a little crazy for those of you
saying you think the acceleration still
matters for the twins paradox well yeah
sure it matters just not in the way
people usually say that it does the
acceleration doesn't suddenly explain
time differences between observers it
just makes it possible for them to
compare notes anyway thanks for watching