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Kip Thorne: The science of Interstellar

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Re: Kip Thorne: The science of Interstellar

#31

Post by 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)

Re: Kip Thorne: The science of Interstellar

#32

Post by lqdc13 »

ThePhysicist wrote: post #17

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 supermass…

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.

Re: Kip Thorne: The science of Interstellar

#33

Post by sangnoir »

gglon wrote: post #15
chton wrote: post #13

Earlier quoted context omitted.

Yes, they knew about the relativistic effects. And they could obviously send some data. But somehow they can't figure out that they've been getting a repeat of the same ping for the last 10 years? And even if they couldn't figure that out, how could the person on the planet possibly send a ping every year, if she only spent an hour and half on it according to her frame of reference?

I don't remember how many pings they received in the movie. I've understood that they had received just one ping from that planet.

If I remember correctly, one of the characters hand-waved it as (paraphrasing) "multiple echoes of the same signal". Meaning there were no meaningful timestamps

Re: Kip Thorne: The science of Interstellar

#34

Post by m_mueller »

Morgawr wrote: post #31

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…

from my layman physics knowledge

* how did he survive inside a black hole

possible for supermassive black holes up to a certain distance from the singularity. To my knowledge there's still the possibility of ring shaped singularities that could be passed through and we don't really know yet what would happen there. Unified quantum gravity theory needed first, so remains in the artistic freedom of the director.

* how did he pass through the Schwarzschild radius with his simple spaceship

Again the only question is whether the tidal forces would be too strong and a supermassive black hole does not have extremely strong forces at its event horizon.

* why was there no time dilation as he approached the black hole

I think there was. After returning from the closely orbiting planet they had a few decades such that he now was a bit younger than his daughter, after coming out of the black hole another 50-60 years have passed for the outside world. Granted though, as far as I understand GRT, actually entering a black hole takes literally forever from the point of view of the outside world (i.e. time breaks down completely), but again, we don't know what would happen with quantum gravity, so maybe the infinity would cancel out somehow if our theories were better.

* why did his spaceship break down inside the black hole but he was able to eject with his simple spacesuit and survive

Tidal forces act the stronger the more vertical distance from the gravitational center an object has in itself (i.e. the height of the object from the singularity's point of view). A spaceship is much larger than a human, so it will break down earlier.

* how did he realistically survive out in cold space (at the end, yes okay I know this is technically possible but still..)

You do have a few minutes in space - the coldness isn't actually a problem since nothing can transport heat in a vacuum. It's rather the pressure difference that will give you trouble, but there are some measures such as emptying your lungs that will give you more time.

Re: Kip Thorne: The science of Interstellar

#35

Post by IndianAstronaut »

chton wrote: post #2

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 ex…

I am actually just happy that they are making movies involving space exploration. We really need to bring back space exploration into the minds of the public so we can get support for awesome missions in the future.

Re: Kip Thorne: The science of Interstellar

#36

Post by m_mueller »

TorKlingberg wrote: post #27
ThePhysicist wrote: post #17

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 supermass…

I also love the movie, but there one thing with the time dilation I suspect does not add up. If the first planet is so deep into Gargantua's gravity well that it has such time dilation, would the energy required to get a spaceship out of the gravity well not be ridiculously huge? Given that they had limited energy, did it make sense to visit that planet first?

The thing about their energy budget was not well done. Why did they need rockets back on earth when they can mount the gravity well of a black hole and multiple planets afterwards? About your point with the order of visits though: I could see them using Gargantua for a slinghot maneuver after the first planet, which should work given the right constellation. It wasn't shown this way though.

Re: Kip Thorne: The science of Interstellar

#37

Post by gonvaled »

Morgawr wrote: post #31

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…

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.

Re: Kip Thorne: The science of Interstellar

#38

Post by drjesusphd »

chton wrote: post #24
martinko wrote: post #21

Earlier quoted context omitted.

> here we have to assume that the black hole is not rotating very fast From the article: "The black hole needs to be spinning very fast"

Calculations about time dilation become enormously more complicated in a system where the black hole is spinning, because you get effects like frame dragging that influence the orbits and time. For the purposes of the parent poster, a ball-park number of distance is enough, they don't need the whole shebang.

> For the purposes of the parent poster, a ball-park number of distance is enough

Citation needed.

It's been said repeatedly that considering the strong rotation of the black hole is critical for the situation in the movie to be possible. "It's hard" is not an excuse to ignore a strong effect.

Re: Kip Thorne: The science of Interstellar

#39

Post by ThePhysicist »

lqdc13 wrote: post #32
ThePhysicist wrote: post #17

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 supermass…

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 th…

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). 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). 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), and you would probably not even notice when you cross the event horizon. Fascinating stuff.

Re: Kip Thorne: The science of Interstellar

#40

Post by chton »

lqdc13 wrote: post #32
ThePhysicist wrote: post #17

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 supermass…

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 th…

I don't know why you're being downvoted, so I'm going to give you a proper reply instead.

Actually, the 2 things you noticed are not that hard to resolve:

- The quantum data was most likely never going to get out of the black hole. They executed the plan on the off chance that TARS was able to figure out how to do it if he had the quantum data. It's not impossible that there is a way to do it, we just don't know it yet.

- Your concern about spaghettification is valid, but the risk of that happening also decreases with the size and mass of the black hole. A stellar mass black hole would rip you apart instantly, but around a supermassive black hole the gravity gradient is a lot gentler. It wouldn't be comfortable per sé, but definitely survivable. You would get ripped apart inside the event horizon, but you could cross it pretty safely.

There is actually a much bigger problem than the spaghettification: every black hole has a shell of light orbiting it at the event horizon. It's light that came in tangentially, and doesn't have enough speed to escape, but is fast enough to keep orbiting. In a black hole of considerable age (like the one in Interstellar), that shell would be very very energetic. I don't know if the ships they were in would be able to survive a blast of radiation that intense, let alone the human and robot inside.

I don't think it's fair to say that they went for emotion over science. They tried to do both, and wanted at least an inclination of accuracy from the start. That's laudable in itself, in a time where most wouldn't bother with that.

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