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Kip Thorne: The science of Interstellar

blogs.scientificamerican.com

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Re: Kip Thorne: The science of Interstellar

#41

Post by ThePhysicist »

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?

Yeah this is indeed true, but sadly most movie plots treat distances badly for practicality reasons. The fact that they were able to leave the gravitational field of the planet they visited just using their "space shuttle" was also highly unrealistic, since that planet had about the same mass as Earth, whose gravity well they had to leave using a conventional rocket earlier in the movie. So this part definitely does not add up.

Re: Kip Thorne: The science of Interstellar

#42

Post by vdaniuk »

harshreality wrote: post #10
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 couldn't agree more. I don't understand why Kip Thorne is so desperate to declare that the movie doesn't violate known physics, when it clearly does, just not in the areas he's most concerned with. Planetary dynamics, propulsion systems... but as long as there aren't Na'vi or dragons on the planets, I suppose they consider it realistic enough. On second thought, Na'vi or dragons might be more realistic than some of…

>I don't understand why Kip Thorne is so desperate to declare that the movie doesn't violate known physics

I do. At least I think I do. Kip Thorne has published a book named "The Science of Interstellar".

I am sure that book is quite scientific and reasonable. However, the most hyped up attribute of art-science relationship in Interstellar is its "real" physics. If Kip Thorne declares that movie does violate known physics in a direct and unambiguous manner the hype instantly decreases. Lots of sci-fi got science very wrong and Interstellar is considered different in that regard by general public. Less hype -> less sales.

Though, this "interstellar science is real" meme may be a trojan horse and it is ripped apart in the book. I know nothing of that as I haven't read the book.

I am not sure if Interstellar is net benefit to the rational and scientific worldview of an average viewer or not. In the end, magic tesseract creatures and love of the protagonists saves the day, not scientific method.

Re: Kip Thorne: The science of Interstellar

#43

Post by ThePhysicist »

NetMonkey wrote: post #25
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…

The time dilation was really quite fascinating. However, I assume that the entire planet would not behave as if it had the same time dilation all the time? Considering the massive dilation (1 hour -> 7 years, a factor of 1 : 61320), wouldn't even relatively small distances on the planet surface create different dilation effects depending on an objects/individuals distance to the black hole? I'm just wondering if ther…

Fascinating question, I'll have to look into this! I was considering writing a blog post about the movie physics already since there are so many fascinating things to be discovered, but I'll maybe check out Kip Thorne's book about the movie first ;)

Re: Kip Thorne: The science of Interstellar

#44

Post by ThePhysicist »

harshreality wrote: post #29
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…

It's a supermassive black hole, spinning at close to the maximum permitted (apparently there's a maximum, beyond which photons at either the photon sphere or an event horizon get dragged faster than the speed of light, and Gargantua's spin is ridiculously close to the maximum for the math on the orbit and time dilation to work out, but it does) If you can find a copy of Thorne's book (it's already leaked to the web)…

A relativistically spinning supermassive black hole might not be very unrealistic indeed, since it will have ingested the angular momentum of a whole galaxy during its growth and concentrated it in a very small region of space.

Re: Kip Thorne: The science of Interstellar

#45

Post by chton »

drjesusphd wrote: post #38
chton wrote: post #24

Earlier quoted context omitted.

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.

ThePhysicist talks about using the bits of information provided in the movie to learn about the basics of some of the physics behind it. That's why he points to the formula for calculating a Scharzschild radius and not the complicated solutions of Einstein's field equation for Kerr (rotating) black holes. As a learning experience, you don't want to dive into the hardest stuff right away. As a you learn, you'll also figure out what was a ball-park number and what wasn't.

Also, the effect is strong, but in all of the formulas you're already guessing factors such as mass of the black hole, which have a far bigger influence on the end result.

Re: Kip Thorne: The science of Interstellar

#46

Post by ThePhysicist »

Osmium wrote: post #23
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…

> here we have to assume that the black hole is not rotating very fast I read that, for Interstellar, it's actually very important to include rotation of the black hole: http://www.slate.com/blogs/bad_astronomy/2014/11/09/interste... > which offer great 'Fermi problems' An aside, but I'm curious. I see this mentioned a lot more often lately, and I know Randall Monroe talks about them a lot in his 'What if?' series, s…

Fermi problems are discussed a lot in Physics, and as a working physicist you always need to be able to quickly estimate the order of magnitude of something when developing ideas for experiments, since calculating everything in detail is usually too time-consuming. So I'd say that this is not a hype but rather a pretty useful skill for any scientist.

Re: Kip Thorne: The science of Interstellar

#47

Post by chton »

Tycho wrote: post #30

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.

I'll just link you to https://en.wikipedia.org/wiki/Novikov_self-consistency_princ...

It's by far my favorite way to explain time travel system like the one we see in Interstellar, and it's rooted in real science rather than Paradox Philosophy.

Re: Kip Thorne: The science of Interstellar

#48

Post by 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.

Re: Kip Thorne: The science of Interstellar

#49

Post by lqdc13 »

ThePhysicist wrote: post #41
TorKlingberg wrote: post #27

Earlier quoted context omitted.

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?

Yeah this is indeed true, but sadly most movie plots treat distances badly for practicality reasons. The fact that they were able to leave the gravitational field of the planet they visited just using their "space shuttle" was also highly unrealistic, since that planet had about the same mass as Earth, whose gravity well they had to leave using a conventional rocket earlier in the movie. So this part definitely does…

I attributed it to the fact that the black hole is very close, so it had a "helping hand". I'm not sure if it adds up though.

Re: Kip Thorne: The science of Interstellar

#50

Post by ceejayoz »

Tycho wrote: post #30

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.

http://en.wikipedia.org/wiki/Closed_timelike_curve

> in a CTC, causality breaks down, because an event can be "simultaneous" with its cause—in some sense an event may be able to cause itself.

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