
Kip Thorne: The science of Interstellar - tonteldoos
http://blogs.scientificamerican.com/observations/2014/11/28/parsing-the-science-of-interstellar-with-physicist-kip-thorne/
======
chton
Surely Kip Thorne himself has to realize that he's grasping at straws. A lot
of the things he mentions are of the type "in this precise, extremely rare
situation it is possible, if we ignore all the other side effects". For
example, I'm sure his calculations will be correct regarding the planet
orbiting a black hole close enough for relativistic effects. What it also
means is that the planet would pass through the extremely hot accretion disk
twice every orbit, killing everything and evaporating all the water. And
considering the speed that a stable orbit would require, that would be a very
common occurrence.

The point is: don't claim that you're scientifically accurate. Usually, a good
sci-fi movie will set up rules for itself, and follow those rules
appropriately. If you make your ruleset "real world physics", you have to be
extremely accurate if you still want to make it believable. The rules set up
expectations, and breaking your own rules is an instant turn-off for science
fiction fans.

The movie shows other cases where it doesn't follow its own rules: they have
spaceplanes that can get to orbit from a planet with 1.8 times earth gravity,
but not from earth without huge boosters?

For the record: I like Interstellar a lot. It was a great film, and I'll
definitely be buying it when it comes out on DVD. I just have my gripes with
the lofty claims of accuracy that Hollywood films so love to make.

~~~
vacri
I liked Intersteller a lot as well, but its plot was horribly contrived in
places and the science isn't as good as it was purported to be - even moreso
if you include the behaviour of the scientists involved :). The science was
certainly better than most other serious sci-fi films though. The real problem
with the film is the needlessly long hour of character establishment.

(SPOILER) Rather interestingly, I've seen very little discussion about the
christ story in the film - the 33-year-old man, who is also the 'father', who
is also the 'ghost'; who disappears presumed dead, only to return; who has the
only information that can save humanity (the 'quantum data') and also
sacrificed himself to save humanity; and who was helped along by 12 others -
one being the questionable [Dr] Man[n] who is weak of spirit. There's a few
more other parallels, but the gist is there.

~~~
lobster_johnson
Not to mention the use of organ music — easily reminiscent of Christian hymns
— in Hans Zimmer's soundtrack:
[https://www.youtube.com/watch?v=jo5m5GXF9Ec](https://www.youtube.com/watch?v=jo5m5GXF9Ec).

The parallels between "quantum data" and the Logos of Gnostic Christianity are
also apparent.

------
ThePhysicist
Accuracy aside, from a scientific point of view Interstellar was one of the
most interesting movies in a long time, and it really made me think about
Physics a lot again.

It's really cool to see how much you can actually learn about the universe of
Interstellar by making use of some Physics knowledge and the information given
to you in the movie.

An example: The first planet they visit orbits Gargantua (the supermassive
black hole mentioned in the movie -
[https://en.wikipedia.org/wiki/Supermassive_black_hole](https://en.wikipedia.org/wiki/Supermassive_black_hole))
at a distance very close to its Schwarzschild radius (or event horizon). In
the movie, they say that the time dilation there is such that one hour passed
at the surface of the planet corresponds to 7 years (!) on Earth.
Interestingly, with that information alone we are already able to calculate
how close the planet is to the Schwarzschild radius of the black hole by using
a really simple formula:
[https://en.wikipedia.org/wiki/Schwarzschild_radius](https://en.wikipedia.org/wiki/Schwarzschild_radius)
(here we have to assume that the black hole is not rotating very fast).

Making some assumptions about the mass of the black hole then allows us to see
how large the actual Schwarzschild radius is in fact, and if the time dilation
shown in the movie is possible (it is). Similarly, if we use the information
they give us about the gravity constant on the planet (about 1.3 times Earth
gravity if I remember correctly) as well as an estimate of the height of the
tidal waves they find there (maybe 200 meters?), we could even estimate the
rotation period of the planet.

There are many more examples of clues like this in the movie, which offer
great 'Fermi problems'
([https://en.wikipedia.org/wiki/Fermi_problem](https://en.wikipedia.org/wiki/Fermi_problem))
and allow us to learn many things about the universe presented to us in
Interstellar.

Of course I also have to mention the absolutely stunning rendering of the
black hole, which incorporated the gravitational lensing effects
([https://en.wikipedia.org/wiki/Gravitational_lens](https://en.wikipedia.org/wiki/Gravitational_lens))
that make the accretion disk of the black hole appear like a halo surrounding
it. Also, the rendering of the wormhole as a four-dimensional "hole" embedded
in three-dimensional space was absolutely gorgeous.

Amazing movie, amazing science, amazing universe.

~~~
lqdc13
Wait what? What about sending "quantum data" back from the black hole? The
point is that no information can leave.

Also, from what I learned in high school physics, the body of a human would
completely fall apart if it's falling to the black hole, because of the
difference in gravity between proximal and distal parts.

These are just the 2 things I noticed and I'm far from a physicist. Basically,
it got a couple of things right and a bunch of things wrong. There was a clear
preference of emotion over science. It just seemed like "The Core" Version
2.0, but here love and reading books conquers all and is beyond the forces of
nature.

I liked Europa Report a lot more even though they didn't invest nearly as much
into special effects.

~~~
ThePhysicist
That's an interesting point! The fact that our current theories suggest that
no information can ever leave a black hole entails a paradox which is known as
the "Black hole information paradox"
([https://en.wikipedia.org/wiki/Black_hole_information_paradox](https://en.wikipedia.org/wiki/Black_hole_information_paradox)).
In the movie they resolve this by resorting to gravitational waves, which can
"permeate" through space and time by a mechanism not explained in the film. In
real physics, there is actually an ongoing debate in the community about
whether information can escape from black holes or not, which resulted in a
famous bet between Stephen Hawking and Kip Thorne on one side and John
Preskill on the other. The fact that Thorne suggests that information can be
sent out from a black hole might therefore be a small stab at John Preskill ;)

Concerning the second point, there is actually a pretty fascinating
explanation: For a small black hole, the "tidal force" when entering the black
hole (i.e. the force difference between your feet and your head) would be so
enormous that you'd probably get ripped apart (so-called "Spaghettification"
\-
[https://en.wikipedia.org/wiki/Spaghettification](https://en.wikipedia.org/wiki/Spaghettification)).
However, the Schwarzschild radius (or event horizon) increases linearly with
the mass of a black hole, whereas the gravitational force declines with the
square of the radius. Hence, for a supermassive black hole with 10 million
solar masses, the tidal force is not bigger than the one you experience here
on Earth
([https://en.wikipedia.org/wiki/Supermassive_black_hole](https://en.wikipedia.org/wiki/Supermassive_black_hole)),
and you would probably not even notice when you cross the event horizon.
Fascinating stuff.

~~~
rufb
They glossed over the tidal force in the movie and I assumed it was a deus ex
of sorts (in fact, I assumed the whole final act of the movie was more
concerned with resolution of the story than with proper Physics). Thank you
for this explanation, this is fascinating stuff.

~~~
magicalist
It's still a gloss over, but one of the characters does mention it early on,
which I took as indication that it was going to end up being important.

I remember having a similar thought process to all of the above, but they even
explicitly call it out as "gentle" with maybe a single really simple sentence
on why it was. I don't remember if they made the direct connection to it being
supermassive (like they did with its rotation), but it was in the same bit of
dialog.

------
arikrak
It sounds like he's just discussing certain aspects of the film, while
ignoring much more glaring issues. It's not ice clouds that are the issue,
it's the entire story.

[Spoiler alert] Here's the whole plot of the movie, does any aspect of it make
sense?

Earth is dusty so the simplest solution is to transport all of humanity
through a wormhole to another planet. The main characters go through a
wormhole and walk around on a planet where 1 hour = 7 years of Earth. Later,
to help the mission succeed, the main character detaches from their main
spaceship into a blackhole and he ends up in a multi-dimensional space where
he sends Morse code messages to his daughter in the past by moving her books
and watch. How does he do that? Because love. And gravity. She understands the
message which contains gravity data from the blackhole that lets them get
everyone off earth. The main character then pops out of the blackhole thing
near Saturn and is re-united with his daughter just before she dies.

~~~
timdiggerm
>he ends up in a multi-dimensional space where he sends Morse code messages to
his daughter in the past by moving her books and watch. How does he do that?

Because the multi-dimensional space was set up by higher-dimensional
creatures, who also created the wormhole, specifically so he could accomplish
all this (right down to preventing him from going on the earlier missions by
causing his craft to crash with a gravitational anomaly at the beginning of
the film).

~~~
debacle
That seems like a rather roundabout way to save the human race, no? A love-
powered hyper-dimensional gateway used to transmit Morse code sounds like
something straight out of h2g2.

~~~
magicalist
(spoilers, obviously) It's a predestination paradox -- so, as with all
predestination paradoxes in fiction, the story is a little too in love with
the use of it -- but the movie sets the ground rule that the only way to
communicate backwards is to manipulate gravity, therefore that's how they're
going to have to accomplish it.

As for the love-powered part, everyone's a little too hung up on that set of
dialog. There's nothing in the plot that relies on it. Sufficiently advanced
magic gravity technology is more than enough. Is any advancement of the plot
motivated by more than the fact that he wants to see his daughter again? Sure,
if they had listened to Brand's feelings they wouldn't have ended up with
crazy guy and would have ended up on a (seemingly) habitable planet, but the
human race also would have died on earth and lived on entirely from the test
tube embryos.

The whole tesseract section doesn't entirely fit with the tone of the rest of
the movie but it's not powered by love.

~~~
debacle
Why not prevent the whole mess by just sending a clear message in Morse to
almost anyone at NASA from the future using gravitational waves?

------
tambourine_man
_spoilers_

I liked the film, and it bothers me a bit that they can launch from a planet
with stronger gravity using tiny rockets, or that we would consider a planet
orbiting the event horizon of a huge black hole as good candidate for our new
home.

But my biggest gripe is with the premisse of the film. We have a catastrophic
ecological disaster, which is unconvincingly explained in a single sentence by
Michael Caine, and our solution is to take the entire species on an
intergalactic travel through a worm hole. Instead of, you know, digging a big
hole right here and creating an artificial biosphere underground. Or maybe
check out Mars or Europa, which are right around the corner.

~~~
patrickk
Or the idea of abandoning Earth because it's too hostile to grow crops with
some dust storms, yet the idea of colonising a distant, extremely harsh-for-
human-life planet is a more realistic idea. Surely building massive "vertical
farms" or other artificial environments here on Earth would be more cost
effective and realistic.

Overall I think we may be thinking too deeply about the plot ;-)

------
nsxwolf
Why was the Ranger launched from Earth on a giant rocket, but was single stage
to orbit on all the other Earth-like worlds?

The only thing I've been able to think of was that they used some kind of
exotic propulsion, like antimatter, therefore there was no sense wasting such
a precious commodity to leave Earth if you had a rocket available.

But nothing in the movie seemed to explain it.

~~~
magicalist
There is the one-off about this being the last of its kind space vehicle, and
the booster pack in orbit had been there for quite some time. You can somewhat
fanwank that into meaning they had to use older, simpler technology to get the
capsule itself into orbit, but then could take advantage of the pre-Blight
technology already in orbit for the rest of the movie. That's about the same
as your explanation, though.

Pretty weak, so it would be nice if they had at least given us a throwaway
sentence or two to wave it away like they did with spaghettification, as the
rocket orbital mechanics, at least, were distracting. I imagine the real
reason was Nolan wanted to invoke a parallel to the Apollo missions in the
liftoff from earth, but didn't want to waste time with the very hard problem
of getting off other worlds once you get there.

------
Morgawr
One thing I cannot understand is... Sure, this movie was very "accurate", all
these explanations can make sense, the calculations fit but.. why is nobody
talking about the major obviously impossible/inconsistent problems in the
plot?

INTERSTELLAR SPOILER BELOW

For example, how did he survive inside a black hole, how did he pass through
the Schwarzschild radius with his simple spaceship, why was there no time
dilation as he approached the black hole, why did his spaceship break down
inside the black hole but he was able to eject with his simple spacesuit and
survive, how did he realistically survive out in cold space (at the end, yes
okay I know this is technically possible but still..)?

When I watched this movie, I saw a lot of problems that made me think "has a
physicist ACTUALLY worked on this and said 'yes, this is accurate'?". And
those certainly weren't the minor details like the time dilation on the
planet, the structure of the black hole and the icy clouds on that one other
planet.

Disclaimer: I enjoyed Interstellar a lot, it was a pretty good movie, although
I felt that at times the director was pretty much screaming in my face: "SEE?
WE ARE SO REALISTIC! LOOK THERE IS NO SOUND IN SPACE, AREN'T WE REALISTIC?"
(sorry for caps lock but it's to provide emphasis)

~~~
gonvaled
SPOILER ALERT

The science was basically non-existing: controlling a distant device with
gravitational waves? Which can only be controlled whenever it is in a specific
room? Which stores the information transmitted and repeats it endlessly
(otherwise, how is the daughter able to gather all information transmitted)?
How long does he spend inside the black hole transmitting what must be like
lots of information in morse code, by slowly pulling gravitational waves?
Looks to me like several hours / days? What is the time dilation of getting
into a black hole if getting into a planet gives you a 1 hour to 7 years
ratio? Getting inside / outside a black hole, unharmed? What part of this is
current physics domain?

More strange facts: the device in the black hole was supposedly man-made ("we
are they"), by the men of the future. But the men of the future can only exist
if this particular crisis is overcome. And this crisis can only be overcome if
this device is in the black-hole. Granted that the man of the future controls
the five dimensions, and thus time, but we currently do not, so we can not in
any way survive this crisis. Which means the men of the future will never be,
so they can not build the device to survive the crisis.

Just the very simple facts are maybe according to the current scientific
knowledge (time dilation, gravity effects, I can even accept a worm-hole), but
most of the movie is just an exercise on futility with a very high dose of
emotions. Boring, slow and not enjoyable at all. The fact that they are
pretending that this is a science-based movie makes it insulting. If you want
to do a Hobbit, do it and I'll have a good time, but do not pretend it is
based on any established science.

Gravity was orders of magnitude better.

~~~
EpicEng
> Gravity was orders of magnitude better.

Gravity was a completely different sort of movie, so the comparison makes
little sense. Gravity was about the here and now, things we understand and can
convey rather easily. This movie explores some of the most strange edges of
our current understanding in order to tell a _story_.

Also, did you miss all of the criticism of the physics in Gravity?

------
drivingmenuts
It's not a science movie. It's fiction. Science is a passenger, not the
vehicle. You want science - go watch a Neil DeGrasse Tyson or Carl Sagan (and
don't get too wound up about how they gloss things over - the kind of science
they're doing is too complicated for an hour long show).

The science used in sci-fi movies is not about the science - it's about the
myth of science; the things we wish science could do or lead us to do. But
more than that, it's about telling a story. We are not relating facts here,
we're off into Joseph Campbell territory.

Even the most scientifically accurate movie is going to do some jazz hands
once in a while just to keep things interesting/heroic/funny/whatever because:
failure is not an option - the movie has to make money.

~~~
JoeAltmaier
All that I could swallow, if only. If only it made any attempt to even fake it
well. If only it didn't ignore plot holes the size of a truck. If I could only
figure out what the plot was, or who the characters were (from moment to
moment), or what they meant by the words that came out of their mouths. If
only it was a real movie, and not just a bunch of images on a screen to give
teenagers the impression they're watching a movie.

~~~
drivingmenuts
All of the problems you mention are problems created by the writer, director,
producers, etc., and have nothing to do with bad science. They can, and
frequently do, show up in every genre of film. One of my favorite films is Big
Trouble in Little China (as an example) and I'm sure there are all kinds of
issues about the film itself, but I still love the film. Ditto Blade Runner,
Brazil, Contact, etc.

Disclaimer: I'm not a scientist by profession.

~~~
JoeAltmaier
Its an interesting question: who failed this movie? The director is easy to
blame - why are characters changing without motivation? Who is connected to
whom, emotionally? What is that grandfather doing there anyhow? How can a
father care deeply about his daughter, but ignore his son (and grandson)? If
there're reasons, let us know!

As for science: its more than technical details. Its why they are so dumb. Why
can a 12-year-old out-guess the plans made by the scientists? (We're in a
terrible hurry; lets set down on a time-dilated planet for a few hours and let
the masses on Earth rot for a decade or two).

Once decided, why park your interstellar ship outside the time-dilation zone,
so you can take your shuttle to the surface? Makes no difference to Earth -
they wait either way. But the ship burns half their fuel, just station-keeping
for 20 years. If it had been time-dilated too, that wouldn't have happened!
Not even to mention the poor sap on the ship, stuck waiting for half his life.

Oh I can go on (have, for hours, to my family's dismay)

------
stillsut
What was the deal with "the blight"?

At one point, they mentioned it had to do with the ability to fix nitrogen?

Also, wouldn't any pestilence as widespread as that be transported on the
cargo ships with the people and their plants to the new planet?

~~~
mcguire
In hard science fiction, "science" is physics. Maybe chemistry, maybe. But
biology is all squishy and such and doesn't carry the mathematical gravitas
needed to be taken seriously.

------
Tycho
Does he explain the glaring paradox of the time travel storyline?

Someone said it is permissible as a 'closed timelike curve' but smells like BS
to me.

~~~
eyevinx
There is no paradox:
[http://www.reddit.com/r/interstellar/comments/2mmh71/spoiler...](http://www.reddit.com/r/interstellar/comments/2mmh71/spoilers_no_alternate_realities_no_paradox/)

~~~
Tycho
maybe I missed something but I don't see how that resolved the paradox

just because you introduce more dimensions, doesn't mean you resolve a paradox
within the existing dimensions

