- If you could run as fast as the Flash,
in my estimation, you'd be the most powerful superhero.
You could think at light speed, you could time travel,
and you could make your punches infinitely more massive.
But would you be fast enough
to take a truly hands-free selfie?
Important questions.
(upbeat music)
Now I don't mean a hands-free photo with a selfie stick
or remote, no, I mean is the Flash fast enough
to hold up a camera, press the button,
and then before the shutter closes,
run to get himself in front of the camera
such that his picture will be taken?
This has already been established in the CW's version
of the Flash so let's put it to the test.
First we have to select a camera shutter speed,
I'm going to choose 1/8000 of a second,
or 125 microseconds because this is what your iPhone
or handheld device usually defaults to
and we wanna minimize blur, so can the Flash,
in this amount of time, run, stop, and provide enough time
afterwards for any photons that hit his body
to impact and then impact the camera sensor?
For that, we need to know the distance traveled.
From how far away is the typical selfie, no filters,
there's actually a lot of filters in this,
well a rough estimate would be that from the tip
of your finger to the center of your chest
is around half your height, so I will say just in general,
one meter, and we don't have to worry about the camera
falling in the travel time either because
in just 125 microseconds, the camera would experience
less free fall than the diameter of a small molecule.
Using one of the equations of motion,
we know that the Flash has to achieve a final speed
such that he can cross one meter of distance
in less than 125 microseconds of time,
we can say 124 because it only takes light 3.3 nanoseconds
to cross this distance, since it's kinda negligible
so it's the same thing, let's try it.
Three, two, one.
To take a truly hands-free selfie,
the Flash would have to be able to achieve a speed
of 16 kilometers per second.
That's a crazy fast speed but canonically,
I think the Flash could do it.
See? Possible.
Sure, the Flash would have to pull 13 million Gs
to pull this off, but that's what the speed force is for.
What if we chose a faster camera?
Using lasers, mirrors, and computer algorithms,
researchers at MIT were able to create a camera
with an effective shutter speed of one trillionth
of a second.
At this frame right, you can see light move.
This camera would make the Flash look slow.
(garbled speaking)
Let's try a selfie with this camera.
Three, two, one.
At this exposure time, light only moves
less than a millimeter so unless the Flash can run
many thousands of times the speed of light,
which we've always used as a limit on this show,
there would be no photo.
In fact, no matter how fast the Flash is,
at one meter away, any photos bouncing off of the Flash
that need to make it back to the camera would not have
enough time to do so before the shutter closes.
The only way that MIT video is possible
is because they are sampling many different exposures,
giving photons time to travel to the camera.
That doesn't really work
but we can calculate something else.
Using a normal camera, what is the maximum distance
the Flash could take a selfie at?
Alright, back to our original situation.
Assume that we have a camera with a megazoom lens on it
with an exposure time of 125 microseconds.
In this amount of time, light can travel over 37 kilometers.
Light is fast.
Okay, I know you're gonna disagree with me here
but I'm also gonna limit the Flash's speed to light speed.
We do this even though the comics say otherwise
because beyond light speed is an unknown quantity
and we wouldn't have anything to work with.
So if we limit him to light speed,
he has to run at light speed, but then leave enough time
for any photons bouncing off of his body
to make it back to the camera, and if you do that,
that limits how far he can go to exactly
half of this distance, 18.6 kilometers.
So if the flash had a mega zooming camera,
he could hold it up, hit the button, run off,
stop about 18 kilometers away, pause for a photo, nice,
and then travel with any photons that hit his body
all the way back to the camera and grab the camera
before it hits the ground.
It should have his photo on it.
It would be the most epic selfie ever.
Ew I don't look good, delete it.
So could the Flash take a truly hands-free photo of himself?
Yes, he's faster than most decent cameras' shutter speeds,
making super selfies possible and he's so fast
that he can take the extreme distance selfie to a max,
taking photos of himself from many many kilometers away.
If you're the Flash,
selfie sticks are even more pointless-er.
Because science.
(upbeat music)
Thank you so much for watching, Kristen.
Not you, the other Kristen.
If you want more weird science stuff,
you can check out the S.P.A.A.C.E. Program
on ProjectAlpha.com where I travel to distant worlds
and try to explain them, and if you want even more
silliness, check out my show with my colleague Dan Casey
called Muskwatch, where we get very silly
about a very serious man.
Thanks.
I thought I had something else, but I don't.
Bye.
I'm gonna take a selfie right now
and I'm gonna post it to my Gram-Gram.
And you will know that I did it for you
if you're still watching, oh that's not good,
gonna delete it.
Ooh.
Okay, we can't keep, oh.
Stop rolling.
Gotta take a good one now.
Oh god, I hate it, stop rolling!
It makes me feel bad.
I'm gonna get out of frame, how bout that?
Ha-ha.
No, don't change the frame!
Go away.
Okay bye, I'm done.