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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

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.

TorKlingberg 12y ago
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?
- m_mueller 12y ago
  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.
  - koepked 12y ago
    Even with a ship capable of overcoming the gravity wells present in the movie, it would likely still make sense to launch from Earth with boosters/staging to increase the amount of fuel/energy available to the ship for the rest of the journey.
    - m_mueller 12y ago
      Yes, that's a valid argument I think. On the other hand, I'd imagine if our technological level is such that we have SSTO ships (with SSTO even for more massive gravity wells than Earth's), we'd probably not use rockets but have another SSTO tanker fueling up the ship in orbit. You could maybe argue that ressource constraints in their dire situation have forged a situation where they put everything they had into those ships and the rockets were just what they had still lying around from an older age, so they made use of it. It certainly was another artistic choice in order to give it a more familiar feel and I can respect that.
      - mcguire 12y ago
        A rocket-scientist (ok, aerospace engineer by training) friend was recently surprised that he hadn't realized this: "If the radius of our planet were larger, there could be a point at which an Earth escaping rocket could not be built. Let us assume that building a rocket at 96% propellant (4% rocket), currently the limit for just the Shuttle External Tank, is the practical limit for launch vehicle engineering. Let us also choose hydrogen-oxygen, the most energetic chemical propellant known and currently capable of use in a human rated rocket engine. By plugging these numbers into the rocket equation, we can transform the calculated escape velocity into its equivalent planetary radius. That radius would be about 9680 kilometers (Earth is 6670 km). If our planet was 50% larger in diameter, we would not be able to venture into space, at least using rockets for transport."[1] [1] http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html http://www.nasa.gov/mission_pages/station/expeditions/expedi...
dr_zoidberg 12y ago
I haven't checked the numbers in any way, but is it safe to assume that the black hole is not rotating "very fast"? In the news covering the render software and papers that will be/have been published, it was mentioned that they were surprised to see the effect the rotation of the black hole has on the accretion disk -- that it bends and twists space and light, so insted of a flat, Saturn-ring-lik disk, you end up with the thing you see in screen.
martinko 12y ago
> 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"
- chton 12y ago
  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.
  - drjesusphd 12y ago
    > 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.
    - chton 12y ago
      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.
Osmium 12y ago
> 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/interstellar_followup_movie_science_mistake_was_mine.html 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, so I'm not sure if it's because of that popularising the term, or if it's just the Baader-Meinhof phenomenon on my part. A Google Trends search suggests increased interest, but it could just be coincidental.
- ThePhysicist 12y ago
  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.
NetMonkey 12y ago
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 there would not only be noticable effects from a distance (orbit -> planet), but also within visible distance on the surface itself. If the dilation could act on scales such as the 200 meter wave, I'm having trouble imagining how it would look / behave, if for example the top of the wave was moving "slower" compared to the bottom of the wave.
- ThePhysicist 12y ago
  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 ;)
snowballsteve 12y ago
The wormhole was perfect, except the travel bit bugged me. They use the 2d analog with paper. The second you pass through the hole in one location you emerge from the hole in the other location. In the third dimension, as they touch the sphere near Saturn they would be leaving the surface of the sphere on the other side. From their point of view they should be about to hit the 'ball' then all of a suddenly then are travelling away from the surface of another ball. Instead they had this tunnel thingy.
- ceejayoz 12y ago
  http://en.wikipedia.org/wiki/Wormhole http://en.wikipedia.org/wiki/Wormhole would seem to indicate that there's a non-zero travel time through one. > However, in 1962 John A. Wheeler and Robert W. Fuller published a paper showing that this type of wormhole is unstable if it connects two parts of the same universe, and that it will pinch off too quickly for light (or any particle moving slower than light) that falls in from one exterior region to make it to the other exterior region.
- seanflyon 12y ago
  Imagine in the 2D analog, if there was a small gap of air between the 2 points on the paper.
  - snowballsteve 12y ago
    Yea I was thinking about that, say a straw. A cylinder to us in the 3d world but in the 2d world one would just see themselves stuck in a circle for awhile. So to up a dimension a 4d whole in a 3d world would I guess appear to us to be a stuck in a sphere? Maybe that is what the movie tried to show, but it still looked like they were travelling in a tube.
sriku 12y ago
Gargantua is a spinning "Kerr" blackhole in the movie. The nearly maximally spinning blackhole is central to the movie plot as it is the reason Miller's planet can be in the orbit it is claimed to be, tidally locked to the spin direction of the blackhole. And the "accretion disc" is not really accreting into the blackhole but is just in orbit around the blackhole, cooling off. The accretion discs and the polar ejections we know from astronomy are energetic medusas that'll fry anything that so much as glances in its direction.
harshreality 12y ago
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) and skim the appropriate sections, it'll clear up some things.
- ThePhysicist 12y ago
  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.
  - harshreality 12y ago
    He addresses that in the book > I found that Chris’s huge slowing of time requires Gargantua to spin almost as fast as the maximum: less than the maximum by about one part in 100 trillion. In most of my science interpretations of Interstellar, I assume this spin. > In 1975, I discovered a mechanism by which Nature protects black holes from spinning faster than the maximum: When it gets close to the maximum spin, a black hole has difficulty capturing objects that orbit in the same direction as the hole rotates and that therefore, when captured, increase the hole’s spin. But the hole easily captures things that orbit opposite to its spin and that, when captured, slow the hole’s spin. Therefore, the spin is easily slowed, when it gets close to the maximum. > Ultimately, when the hole’s spin reaches 0.998 of the maximum, an equilibrium is reached, with spin-down by the captured photons precisely counteracting spin-up by the accreting gas. This equilibrium appears to be somewhat robust. In essence, the necessary spin (for an object to stably orbit at a distance for the time dilation needed for the plot), while possible, is not sustainable, based on what we know about physics. But it's allowable as real physics, because there could be some exotic physics involved in keeping Gargantua spinning that fast, possibly intervention by the civilization that created the tesseract.
lqdc13 12y ago
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.
- nilkn 12y ago
  I'm not going to comment on the "cosmic censorship" hypothesis of black holes since that's actually an incredibly difficult topic, but regarding the tidal forces that would rip you apart, there are certainly large enough black holes that would allow you to comfortably enter the event horizon without being ripped apart. But just to give you a taste of how counter-intuitive this subject can be, consider that despite the fact that light cannot escape a black hole it is conjectured (by Hawking no less) that black holes can emit radiation! (The mystifying mechanism of this involves, very roughly, quantum fluctuations at the event horizon spontaneously giving rise to particle/anti-particle pairs, with one particle of negative mass falling into the horizon and the other of positive mass going out.) The event horizon is only the "point of no return" insofar as it's the imaginary boundary inside of which even the forward light cones are oriented towards the center of the sphere (so that light cannot escape no matter what direction it's emitted in). It's not the point at which the tidal forces are so strong that matter is ripped apart (or even just your macroscopic body).
- ThePhysicist 12y ago
  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.
max55 12y ago
Remember a black hole will crush a galaxy, but not a dude in a space suit.
- bestpcinfos 12y ago
  Don't forget to put the tarp over the ham basin before departing for olfactory shoes.

TorKlingberg 12y ago

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?

m_mueller 12y ago
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.
- koepked 12y ago
  Even with a ship capable of overcoming the gravity wells present in the movie, it would likely still make sense to launch from Earth with boosters/staging to increase the amount of fuel/energy available to the ship for the rest of the journey.
  - m_mueller 12y ago
    Yes, that's a valid argument I think. On the other hand, I'd imagine if our technological level is such that we have SSTO ships (with SSTO even for more massive gravity wells than Earth's), we'd probably not use rockets but have another SSTO tanker fueling up the ship in orbit. You could maybe argue that ressource constraints in their dire situation have forged a situation where they put everything they had into those ships and the rockets were just what they had still lying around from an older age, so they made use of it. It certainly was another artistic choice in order to give it a more familiar feel and I can respect that.
    - mcguire 12y ago
      A rocket-scientist (ok, aerospace engineer by training) friend was recently surprised that he hadn't realized this: "If the radius of our planet were larger, there could be a point at which an Earth escaping rocket could not be built. Let us assume that building a rocket at 96% propellant (4% rocket), currently the limit for just the Shuttle External Tank, is the practical limit for launch vehicle engineering. Let us also choose hydrogen-oxygen, the most energetic chemical propellant known and currently capable of use in a human rated rocket engine. By plugging these numbers into the rocket equation, we can transform the calculated escape velocity into its equivalent planetary radius. That radius would be about 9680 kilometers (Earth is 6670 km). If our planet was 50% larger in diameter, we would not be able to venture into space, at least using rockets for transport."[1] [1] http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html http://www.nasa.gov/mission_pages/station/expeditions/expedi...

dr_zoidberg 12y ago

I haven't checked the numbers in any way, but is it safe to assume that the black hole is not rotating "very fast"? In the news covering the render software and papers that will be/have been published, it was mentioned that they were surprised to see the effect the rotation of the black hole has on the accretion disk -- that it bends and twists space and light, so insted of a flat, Saturn-ring-lik disk, you end up with the thing you see in screen.

martinko 12y ago

> 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"

chton 12y ago
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.
- drjesusphd 12y ago
  > 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.
  - chton 12y ago
    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.

Osmium 12y ago

> 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/interstellar_followup_movie_science_mistake_was_mine.html 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, so I'm not sure if it's because of that popularising the term, or if it's just the Baader-Meinhof phenomenon on my part. A Google Trends search suggests increased interest, but it could just be coincidental.

ThePhysicist 12y ago
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.

NetMonkey 12y ago

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 there would not only be noticable effects from a distance (orbit -> planet), but also within visible distance on the surface itself. If the dilation could act on scales such as the 200 meter wave, I'm having trouble imagining how it would look / behave, if for example the top of the wave was moving "slower" compared to the bottom of the wave.

ThePhysicist 12y ago
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 ;)

snowballsteve 12y ago

The wormhole was perfect, except the travel bit bugged me. They use the 2d analog with paper. The second you pass through the hole in one location you emerge from the hole in the other location. In the third dimension, as they touch the sphere near Saturn they would be leaving the surface of the sphere on the other side. From their point of view they should be about to hit the 'ball' then all of a suddenly then are travelling away from the surface of another ball. Instead they had this tunnel thingy.

ceejayoz 12y ago
http://en.wikipedia.org/wiki/Wormhole http://en.wikipedia.org/wiki/Wormhole would seem to indicate that there's a non-zero travel time through one. > However, in 1962 John A. Wheeler and Robert W. Fuller published a paper showing that this type of wormhole is unstable if it connects two parts of the same universe, and that it will pinch off too quickly for light (or any particle moving slower than light) that falls in from one exterior region to make it to the other exterior region.
seanflyon 12y ago
Imagine in the 2D analog, if there was a small gap of air between the 2 points on the paper.
- snowballsteve 12y ago
  Yea I was thinking about that, say a straw. A cylinder to us in the 3d world but in the 2d world one would just see themselves stuck in a circle for awhile. So to up a dimension a 4d whole in a 3d world would I guess appear to us to be a stuck in a sphere? Maybe that is what the movie tried to show, but it still looked like they were travelling in a tube.

sriku 12y ago

Gargantua is a spinning "Kerr" blackhole in the movie. The nearly maximally spinning blackhole is central to the movie plot as it is the reason Miller's planet can be in the orbit it is claimed to be, tidally locked to the spin direction of the blackhole. And the "accretion disc" is not really accreting into the blackhole but is just in orbit around the blackhole, cooling off. The accretion discs and the polar ejections we know from astronomy are energetic medusas that'll fry anything that so much as glances in its direction.

harshreality 12y ago

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) and skim the appropriate sections, it'll clear up some things.

ThePhysicist 12y ago
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.
- harshreality 12y ago
  He addresses that in the book > I found that Chris’s huge slowing of time requires Gargantua to spin almost as fast as the maximum: less than the maximum by about one part in 100 trillion. In most of my science interpretations of Interstellar, I assume this spin. > In 1975, I discovered a mechanism by which Nature protects black holes from spinning faster than the maximum: When it gets close to the maximum spin, a black hole has difficulty capturing objects that orbit in the same direction as the hole rotates and that therefore, when captured, increase the hole’s spin. But the hole easily captures things that orbit opposite to its spin and that, when captured, slow the hole’s spin. Therefore, the spin is easily slowed, when it gets close to the maximum. > Ultimately, when the hole’s spin reaches 0.998 of the maximum, an equilibrium is reached, with spin-down by the captured photons precisely counteracting spin-up by the accreting gas. This equilibrium appears to be somewhat robust. In essence, the necessary spin (for an object to stably orbit at a distance for the time dilation needed for the plot), while possible, is not sustainable, based on what we know about physics. But it's allowable as real physics, because there could be some exotic physics involved in keeping Gargantua spinning that fast, possibly intervention by the civilization that created the tesseract.

lqdc13 12y ago

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.

nilkn 12y ago
I'm not going to comment on the "cosmic censorship" hypothesis of black holes since that's actually an incredibly difficult topic, but regarding the tidal forces that would rip you apart, there are certainly large enough black holes that would allow you to comfortably enter the event horizon without being ripped apart. But just to give you a taste of how counter-intuitive this subject can be, consider that despite the fact that light cannot escape a black hole it is conjectured (by Hawking no less) that black holes can emit radiation! (The mystifying mechanism of this involves, very roughly, quantum fluctuations at the event horizon spontaneously giving rise to particle/anti-particle pairs, with one particle of negative mass falling into the horizon and the other of positive mass going out.) The event horizon is only the "point of no return" insofar as it's the imaginary boundary inside of which even the forward light cones are oriented towards the center of the sphere (so that light cannot escape no matter what direction it's emitted in). It's not the point at which the tidal forces are so strong that matter is ripped apart (or even just your macroscopic body).
ThePhysicist 12y ago
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.

max55 12y ago

Remember a black hole will crush a galaxy, but not a dude in a space suit.

bestpcinfos 12y ago
Don't forget to put the tarp over the ham basin before departing for olfactory shoes.