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View Full Version : Interstellar science- bit of a spoiler...



starcanuck64
2015-Sep-23, 11:21 PM
I finally got around to seeing Interstellar on Netflix and was a little disappointed - which is fairly common for me these days with a lot of movies.

I know they got kudos for getting the visual effects of a black hole right but some other things in the movie bugged me, I was wondering if I was getting it wrong. The first planet they landed on was basically a smooth ball with a few feet of water apparently covering everything. What looked like mountains in the distance turned out to be a massive tidal wave constantly circling the planet I'm guessing due to the gravitational affect of Gargantua.

The problem I had with that is a wave has.... well a wave form. Long before the wave got anywhere near the ship the water would have receded in the same way the water recedes before a very large wave hits the shore here on Earth. But in the movie the water stays the same depth until the huge wave arrives.

Another thing was the second planet they landed on where Mann was. Were those floating ice clouds they had to avoid coming down then landed on? Ice weighs far more than a gas and if gravity there was normal enough for them to walk around on the huge blocks of ice floating in the sky then they probably wouldn't do that.

There was also the effort to land on the water planet in such a way as to avoid losing too much time due to how close it was to the black hole- I think one hour on that planet was equal to seven years on Earth. They approached in an orbit around the black hole that left them outside the planet in the gravity well. Also they were doing all these trips in a single stage rocket that had needed multiple stages to get into orbit around the Earth. If you throw in not just climbing out of a planets gravity but also out of the intense gravity around a black hole, where were they getting the necessary velocity to do all that.

It wasn't a bad show, I just hoped for something a little more imaginative and a bit more precise in regards to actual science.

DaveC426913
2015-Sep-24, 01:13 AM
The problem I had with that is a wave has.... well a wave form. Long before the wave got anywhere near the ship the water would have receded in the same way the water recedes before a very large wave hits the shore here on Earth. But in the movie the water stays the same depth until the huge wave arrives.

Waves in shallow water do not behave the same as waves in our oceans. The bottom slows down their base, letting the crest catch up.
Think about a wave near a beach, on the verge of breaking.



Another thing was the second planet they landed on where Mann was. Were those floating ice clouds they had to avoid coming down then landed on? Ice weighs far more than a gas and if gravity there was normal enough for them to walk around on the huge blocks of ice floating in the sky then they probably wouldn't do that.
Well, we don't know what the gravity is, it could be quite low.
And we don't know what kind of frozen vapor that is. It's probably not dense. Could be 99% empty crystaline.



There was also the effort to land on the water planet in such a way as to avoid losing too much time due to how close it was to the black hole- I think one hour on that planet was equal to seven years on Earth. They approached in an orbit around the black hole that left them outside the planet in the gravity well. Also they were doing all these trips in a single stage rocket that had needed multiple stages to get into orbit around the Earth. If you throw in not just climbing out of a planets gravity but also out of the intense gravity around a black hole, where were they getting the necessary velocity to do all that.

Yup. This has been widely criticized.


It wasn't a bad show, I just hoped for something a little more imaginative and a bit more precise in regards to actual science.
More imaginative??? Did you find this story too much like so many other stories?

They had to balance between trying to faithfully represent some really exotic physics with being able to actually have a story. It's almost impossible to do both. I think they made a pretty good compromise, but a lot of people feel the same way you do.

starcanuck64
2015-Sep-24, 03:12 AM
Waves in shallow water do not behave the same as waves in our oceans. The bottom slows down their base, letting the crest catch up.
Think about a wave near a beach, on the verge of breaking.

Okay, in that case it was very cool.


Well, we don't know what the gravity is, it could be quite low.
And we don't know what kind of frozen vapor that is. It's probably not dense. Could be 99% empty crystaline.

It appeared to be near Earth gravity and the ice was also supporting the different mission landers. I'll watch it again to get a better idea of what was going on.


More imaginative??? Did you find this story too much like so many other stories?

No...and yes. I can't even really put my finger on it, there just seems to be an element missing that I needed to take the movie over the top. But maybe after a half century my tastes are getting a bit jaded.


They had to balance between trying to faithfully represent some really exotic physics with being able to actually have a story. It's almost impossible to do both. I think they made a pretty good compromise, but a lot of people feel the same way you do.

It was definitely much better than Gravity in this regard. I was just a little disappointed but a lot less than I am with a lot of what's been coming out in recent years where action seems to take a much more dominant position over story. The story was good here and very interesting in some regards, the whole fifth dimensional beings using a black hole to send messages back in time was very imaginative.

Noclevername
2015-Sep-24, 03:52 AM
Added: SPOILERS

The reason the landers could SSTO from three planets was that they were actually given a gravity boost by the future beings who turned out to be Cooper and his robot inside a black hole where time is a linear movement and the gravity of a finger moved the books that convinced Murphy that there was a ghost and then the tesseract collapsed and Cooper went only a little into the future then went back into the wormhole and oh my, I've gone cross-eyed.

starcanuck64
2015-Sep-24, 04:01 AM
Added: SPOILERS

The reason the landers could SSTO from three planets was that they were actually given a gravity boost by the future beings who turned out to be Cooper and his robot inside a black hole where time is a linear movement and the gravity of a finger moved the books that convinced Murphy that there was a ghost and then the tesseract collapsed and Cooper went only a little into the future then went back into the wormhole and oh my, I've gone cross-eyed.

:D

grant hutchison
2015-Sep-24, 04:16 PM
According to Kip Thorne, the ridiculously energy-intensive flight of the lander was assisted by slingshots around another black hole that isn't mentioned in the movie at all.

And they water wave on Miller is essentially impossible without more undisclosed plot elements. In this case Miller's rotation has to be constantly driven to stop it becoming tidally locked - indeed, the tidal spindown time for the parameters of the Miller-Gargantua system is on a social rather than an geological time scale. And then the planet would need to be actively cooled in some way to stop the ocean boiling from the continuous tidal dissipation.

Grant Hutchison

DaveC426913
2015-Sep-26, 09:17 PM
Added: SPOILERS

The reason the landers could SSTO from three planets was that they were actually given a gravity boost by the future beings...

This is the first time I am hearing of such an explanation. Did you read this somewhere, or are you speculating? Or are you just kidding?

Noclevername
2015-Sep-26, 10:33 PM
This is the first time I am hearing of such an explanation. Did you read this somewhere, or are you speculating? Or are you just kidding?

Kidding.

grant hutchison
2015-Sep-29, 12:42 PM
Actually, I got it wrong. There are four intermediate-mass black holes required for all the manoeuvring between planets (requiring delta-vs that are a large fraction of the speed of light), none of which gets mentioned in the movie. There's an out-of-the-blue mention of a neutron star slingshot at one point, but that wouldn't work, according to Kip Thorne. Christopher Nolan refused to have mention of additional black holes because he thought it would be confusing.

Grant Hutchison

CJSF
2015-Sep-29, 01:14 PM
... because he thought it would be confusing.

Grant Hutchison
Somewhat ironic.

I could forgive most of the compromised science (and do, for many science fiction endeavors), but there was just too much nonsense going on in that film - not to mention the purposefully overbearing "musical" score and Love as a force of nature... I really wanted to like the movie, I really did. The more I think about it the less I like it, though.

CJSF

Noclevername
2015-Sep-29, 02:42 PM
Before I saw the film, I remember all the hype about how they had a real science guy helping with making the wormhole physics realistic. Then I saw it, and the bits about "ghosts" and gravity messages came on, and it stopped being science for me. And then when Cooper fell in the hole, it really stopped being science and became pure fantasy.

starcanuck64
2015-Sep-29, 06:19 PM
Before I saw the film, I remember all the hype about how they had a real science guy helping with making the wormhole physics realistic. Then I saw it, and the bits about "ghosts" and gravity messages came on, and it stopped being science for me. And then when Cooper fell in the hole, it really stopped being science and became pure fantasy.


Thanks, you put the finger on why I couldn't really get into this movie.

grant hutchison
2015-Sep-29, 06:23 PM
The count keeps going up.
Every delta-v manoeuvre in the Gargantua environment needs a black hole slingshot, with the exception of the separation from Endurance at the critical orbit, when Coop and TARS fall into Gargantua and Brand is launched towards Edmunds' Planet in Endurance.
In The Science Of Interstellar, Thorne specifically mentions five such manoeuvres, but more are implied.

Two for the descent from Endurance's parking orbit to Miller's Planet (Thorne stipulates these).
Two for the return to Endurance from Miller's Planet (Thorne doesn't mention these, but there seems to be no other way to reverse the journey).
Two to move Endurance from parking orbit to Mann's Planet (Thorne stipulates these).
It's not clear if one is required to get Endurance into the inner critical orbit after leaving Mann's Planet (Thorne stipulates that Mann's Planet has looped close to Gargantua at this time, but there would seem to be a need for significant delta-v to circularize Endurance's orbit into the critical orbit.
A small boost at the critical orbit sends Coop and TARS into Gargantua, and Brand on her way to Edmunds' Planet - no slingshot required.
According to Thorne, Coop needs another slingshot to adjust his velocity before he falls into Gargantua, so that he can survive long enough to reach the tesseract.
It seems likely that Brand is going to need a final slingshot to match velocities with Edmunds' Planet.

So eight or nine close passes of intermediate-mass black holes are invoked for all the travelling in the movie, although never mentioned. And they all have to be in the right place at the right time.

Grant Hutchison

starcanuck64
2015-Sep-29, 06:37 PM
Does he explain how you'd get the formation of multiple intermediate sized black holes around a very large one. Or if they would be in stable orbits, wouldn't they all eventually end up inside Gargantua?

Noclevername
2015-Sep-29, 06:54 PM
Or if they would be in stable orbits, wouldn't they all eventually end up inside Gargantua?

Would the planets, too?

grant hutchison
2015-Sep-29, 06:55 PM
IMBHs are thought to form at the cores of globular clusters, "... and some of these are likely to find their way into the nuclei of galaxies, where gigantic black holes reside."
IMBHs passing through the core region are then braked into orbit around the central supermassive black hole by a process called dynamical friction - they gravitationally interact with the high density of normal stars in the vicinity.
So Thorne is imagining Gargantua to be surrounded by a cloud of IMBHs, from which Coop can pick suitable candidates for his multiple slingshots. They'd be in stable orbits as far in as Miller's Planet (which is in the last stable orbit above the event horizon) so they're available for all the interplanetary manoeuvres. I guess Coop would need to happen upon one falling into Gargantua alongside him for that final tweak to his velocity to give him a survivable trajectory beneath the event horizon.

As Thorne writes: "The probability of finding IMBH's at the needed locations and times is small ..."

Grant Hutchison

grant hutchison
2015-Sep-29, 06:58 PM
Would the planets, too?No, there are stable orbits around black holes in just the way there are around ordinary stars. Things only get unstable when close to the event horizon. But Thorne needed to set Gargantua rotating unfeasibly fast in order to place a stable orbit close enough to give Miller's Planet its extremely high gravitational time dilation.

Grant Hutchison

Noclevername
2015-Sep-29, 07:05 PM
So Thorne worked out a whole constellation of black holes in the Gargantua system, and none of that made it to the screen? Even a one-line mention of them would have been good enough, without adding much for the audience to keep in their heads.

starcanuck64
2015-Sep-29, 07:12 PM
I didn't realize that Gargantua was the core black hole of a galaxy, I guess the story assumes the core is in a dormant state. A galactic nucleus is a deadly place to be in the active stage when the massive black hole is consuming its accretion disk. That's what my avatar is btw...

CJSF
2015-Sep-29, 07:44 PM
Since the future "us" managed to generate a wormhole and the future Coop played harp with gravity strings, I don't think manipulating a black hole system would be out of the question, would it?

CJSF

grant hutchison
2015-Sep-29, 08:14 PM
So Thorne worked out a whole constellation of black holes in the Gargantua system, and none of that made it to the screen? Even a one-line mention of them would have been good enough, without adding much for the audience to keep in their heads.It's pretty obvious from the book that Thorne just ran around trying to find mechanisms for whatever Christopher Nolan put on screen. At one point Nolan stipulates the time dilation he wants for Miller's World, Thorne says that it's extraordinarily unlikely, and Nolan says, "This is not negotiable."
Often Thorne writes something like "my scientific interpretation is ..." which seems to imply that he's doing a bit of post hoc fixer-uppery.

It's just the usual role of the "scientific adviser" on a movie, in other words. I'd guess Thorne was contractually obliged to produce the book, which must have been a slightly disheartening project, for all the enthusiasm he puts down on the page.

Grant Hutchison

grant hutchison
2015-Sep-29, 08:20 PM
I didn't realize that Gargantua was the core black hole of a galaxy, I guess the story assumes the core is in a dormant state. A galactic nucleus is a deadly place to be in the active stage when the massive black hole is consuming its accretion disk. That's what my avatar is btw...Gargantua needs to be supermassive to get the time dilation on Miller's World that Nolan wanted, without tidal forces that would disrupt the planet.
And, yes, the accretion disc is intended to be "cool" and relatively inactive. It should still have been making life dramatically uncomfortable in the vicinity of Miller's World, but then, that's only one of many implausible things about Miller's World.

Grant Hutchison

Noclevername
2015-Sep-29, 08:49 PM
There had to be a hot enough accretion disc to keep the planets lit and relatively defrosted, I think. No stars in the vicinity.

As the whole system seemed (to me, in retrospect) to be basically an artifact of the future-not-aliens, they might possibly be assumed to keep the disk under control as well. Certainly they made the inside of Gargantua hospitable to man and bot, why wouldn't they do the same for the outside?

starcanuck64
2015-Sep-29, 10:21 PM
Since the future "us" managed to generate a wormhole and the future Coop played harp with gravity strings, I don't think manipulating a black hole system would be out of the question, would it?

CJSF

Probably not, who knows what kind of abilities operating with an extra dimension would give them. Opening and maintaining a wormhole takes an incredible amount of energy for instance. I have no idea how you'd get around the barrier posed by the event horizon, I don't think well in five dimensions I guess.

grant hutchison
2015-Sep-30, 11:14 AM
With reference to Miller's Planet and the giant wave, Thorne is evidently playing catch-up again, retrospectively trying to justify something Nolan put in to the screenplay. He writes that he has two "scientific interpretations" of the giant wave - either a tidal bore or a tsunami.
In both cases he ascribes the formation of the wave to an oscillation in Miller's Planet, rather than rotation. The planet is in mean synchronous rotation, but oscillating a little back and forth. That induces a slosh in the oceans and a flex in the crust. He has presumably gone for that interpretation because rotation is pretty much out of the question for this world, given Gargantua's tidal effects. (Plugging an Earth-like world into Miller's orbit, I get a tidal spindown period of two days under Newtonian gravity!)
Interestingly, although Thorne calculates the oscillation period for Miller's (on the order of an hour), he suggests that the reader might like to calculate how long the oscillation could persist without decaying to strict synchrony. He says Newtonian calculations are acceptable approximations. Given the tidal spindown time, I doubt if the oscillation could last much longer than a few days. So Miller's Planet is being kept rocking by some external influence.
Again, that fits with the idea that the entire Gargantua system is a put-up job by the Pan Dimensional Hyperbeings. I don't know what their motive would be for setting up Miller's as trap for the unwary, however.

Grant Hutchison

Swift
2015-Sep-30, 12:54 PM
I could forgive most of the compromised science (and do, for many science fiction endeavors), but there was just too much nonsense going on in that film - not to mention the purposefully overbearing "musical" score and Love as a force of nature... I really wanted to like the movie, I really did. The more I think about it the less I like it, though.

CJSF
I hadn't thought about it exactly that way, but reading your post and thinking about it now... yep, that kind of sums it up for me. I liked it when I first saw it (though I didn't think it was great), but the more I think about it, the less I like it.

Noclevername
2015-Sep-30, 02:29 PM
Again, that fits with the idea that the entire Gargantua system is a put-up job by the Pan Dimensional Hyperbeings. I don't know what their motive would be for setting up Miller's as trap for the unwary, however.


Maybe it's not meant to be visited, that's just where they plan to keep all their tropical fish. :) Or it (and Mann's world) serves some other unknown non-habitability-related purpose and liquid water is a side effect.

starcanuck64
2015-Sep-30, 05:00 PM
Maybe it's not meant to be visited, that's just where they plan to keep all their tropical fish. :) Or it (and Mann's world) serves some other unknown non-habitability-related purpose and liquid water is a side effect.

Or visited for short periods by surfers...

starcanuck64
2015-Sep-30, 06:56 PM
Also if the hyper-dimensional beings are able to manipulate time and space to the degree they'd need to to create and maintain a wormhole and an artificial environment based around a super-massive black hole...then why not fix the relatively simple problems back on Earth.

CJSF
2015-Sep-30, 07:03 PM
Also if the hyper-dimensional beings are able to manipulate time and space to the degree they'd need to to create and maintain a wormhole and an artificial environment based around a super-massive black hole...then why not fix the relatively simple problems back on Earth.
Because if they fixed the problems, they might alter events that lead to their existence, therefore there would be no one to have gone back to fix things.... ;)

CJSF

Noclevername
2015-Sep-30, 07:11 PM
Also if the hyper-dimensional beings are able to manipulate time and space to the degree they'd need to to create and maintain a wormhole and an artificial environment based around a super-massive black hole...then why not fix the relatively simple problems back on Earth.

Maybe they wanted to give us the chance to do it ourselves? Who knows, maybe Earth did get fixed behind the scenes.

Alternately, the future beings are actually the evolved descendants of the crop blight! They want Earth for their own ancestors. But they aren't cruel, they did save some human colonies to grow (being bacterial they have no sense of individual death or survival).

starcanuck64
2015-Sep-30, 08:11 PM
Maybe they wanted to give us the chance to do it ourselves? Who knows, maybe Earth did get fixed behind the scenes.

Alternately, the future beings are actually the evolved descendants of the crop blight! They want Earth for their own ancestors. But they aren't cruel, they did save some human colonies to grow (being bacterial they have no sense of individual death or survival).

The mighty blighty.:)