One of the most thrilling part in Nolan's movie "Interstellar"
is black hole Gargantua and its accretion disk.
Its weird shape has attracted lots of attention.
After watching the movie, we might wonder,
how a black hole actually looks like?
I believe you have all seen many pictures of black holes.
Something like this...
And a trendy photo released a few months back.
Anyway, there are numerous pictures of black holes on google.
But unfortunately, most of them are...
FAKE NEWS!
Except for this photo which has only around ten effective pixels,
this one,
and images of black hole in "Interstellar",
The rest are entirely unreal.
Furthermore, what these three images described
are completely different,
so if someone tells you that the images in "Interstellar"
are similar to the photo shot by scientists, that is FAKE NEWS as well.
But in fact, even images in "Interstellar" has
been drastically edited for artistic purposes,
and ignored a lot of physical effects.
So now I am going to present you
A physically correct accretion disk 
as observed by the naked eye.
Are you ready? three...two...one...
It is okay if you did not see it clearly, let's see it again...
three...two...one...
What? You still did not see it?
That's right, because this should be your state right now.
In fact, what is happening in accretion disks around black holes
are the most dramatic reactions in the universe. In the procedure,
one-tenth or even more of mass will be converted into energy
and emit as gamma rays.
In comparison, the efficiency of nuclear bombs cannot reach 10% of this.
So, naturally, if you actually look at a black hole's accretion disk,
you would be blind instantly.
Nobody would be satisfied with this result,
So I asked the materials in the accretion disk to...
well... cool down a bit.
Then we see the following video.
This video illustrates what you would see if you are 
stationary at 6 times the Schwarzschild radius.
On the left,
because materials are moving towards you,
so due to the Doppler effect, the frequency of light increases,
and the color will be brighter and more blue-ish. And for the same reason, it is darker and more red-ish on the right.
There are three observable 'rings'. The part near you in the outmost ring seems ordinary enough,
but the part further away is tilting upwards.
Ah, this is because black hole bent the light beam.
For light beam that is closer to the black hole,
the effect of bending is more significant
and might even let the light circle around the black hole for more than one round.
This is the source of the inner two rings.
But obviously, this kind of severely twisted light is not the majority,
So the inner rings are dimmer.
In fact, there are even the fourth, or the fifth,
or even more rings, but they are too dark
and all cramming together, so It would be hard for you to see them.
Furthermore, It would be more realistic if you are rotating around the black hole.
So can we simulate that?
The answer is yes! This is what you would see if you are 
orbiting the black hole.(movement of the accretion disk has been accelerated)
As you can see, this is still far away from what is in "Interstellar"
(And less beautiful...)
You would see a more twisted figure because 
Your movement would cause light to shift and aggregate towards the movement direction,
that is right, so the left part would seem more spacious, 
while the right part would seem more cramming.
At the same time, the movement of you would cancel out part of 
The redshift and blueshift we have talked about.
So the left part would be less bight and blue, while the right part less dim and red.
That is exciting, are there any more of this?
If you want to know about the physics behind this video, please check the second video~ (NO EQUATIONS!)
