Interstellar: A Visual Masterpiece with Disappointing Writing and Physics

[Fredrik]

You are right, we are just following a slightly different track.
It's as DaveC426913 said: it's easier to grasp it if we calculate with speed (change) instead of gravity potential. But both view is 'right'. Yours might be a bit more accurate (and also harder to discuss as in this case it's about a really special case of general relativity).

Mine is an oversimplification, since I'm ignoring that the black hole is rotating and that the mothership and planet are both in orbit around the black hole. It might be close enough to the actual answer, but this is far from certain. The velocity argument is completely missing the detail that's the reason for the age difference in the oversimplified picture, so it's very likely to be completely wrong.

The only way to settle this is to calculate the proper times of the relevant world lines in a Kerr spacetime.

 

[OmCheeto]

Agreed. I noticed that when I started thinking about just how far apart the two orbits must be (in distance, but more importantly in orbital delta v!) to get a factor 60,000 time dilation between them.

So, we;re not just talking about a climb out of a gravity well, we're also talking about an orbital speed-matching.I am beginning to see that this one plot point is a far more egregious scientific error than all the rest put together.

KT really should have made the dilation factor much, MUCH smaller - say 3,000 times smaller - and found some reason to strand them on the planet for months or a year. Then that 20 years could have passed with a slightly less outrageous science blunder.

First off, I'd just like to say the science is now way over my head.
Secondly, I think the 60,000 factor may have some relevance for the sequel.
Do you remember the guy they left for dead? When Cooper flies back through the wormhole, he's going to get a scratchy message; "Hey! I'm still alive. Can you come pick me up, PLEASE..."

I'm basing this idea purely Hollywood physics, of course.

 

[QuantumPion]

First off, I'd just like to say the science is now way over my head.
Secondly, I think the 60,000 factor may have some relevance for the sequel.
Do you remember the guy they left for dead? When Cooper flies back through the wormhole, he's going to get a scratchy message; "Hey! I'm still alive. Can you come pick me up, PLEASE..."

I'm basing this idea purely Hollywood physics, of course.

Time dilation wouldn't make a message delayed and then suddenly appear decades later. It would make the message redshifted and slowed down. Even with a factor of 60,000, you could still receive about 1.4 seconds of message per day.

 

[dragoneyes001]

"I'm alive and now the interstellar record holder for biggest wave surfer in history! Aloha!"

 

[Matterwave]

The whole planet was in a high grav potential.

In a nutshell, getting to the planet required them to get nearer the BH.

They had a quick diagram showing this.

View attachment 75767

But how in the world do you fine tune the black hole's potential to give you high potential something like 100km away from low potential? It doesn't seem like it would work unless the black hole itself was ~a few 10's of km in size... and at that point I would be very doubtful that the planet can get so close and still have an orbit...

 

[DaveC426913]

But how in the world do you fine tune the black hole's potential to give you high potential something like 100km away from low potential?

Where did 100km come from? We have no idea how far the Endurance's orbit was above the planet's orbit.

It doesn't seem like it would work unless the black hole itself was ~a few 10's of km in size... and at that point I would be very doubtful that the planet can get so close and still have an orbit...

I've been thinking that myself.

Unfortunately, this plot point is getting squeezed between a rock and a hard place, because to have such a high gradient also means there is a high gradient across the planet's diameter. i.e. colossal tidal forces will rip the planet to rubble. Gotta be well within the Roche Limit.

 

[Matterwave]

Where did 100km come from? We have no idea how far the Endurance's orbit was above the planet's orbit.

I guess it sort of looked that way to me when I was watching the movie. I didn't see Endurance being a huge distance away from the planet.

 

[hankaaron]

Unfortunately, this plot point is getting squeezed between a rock and a hard place, because to have such a high gradient also means there is a high gradient across the planet's diameter. i.e. colossal tidal forces will rip the planet to rubble.

But the gradient shouldn't be greater than the inverse square law, right?

 

[DaveC426913]

But the gradient shouldn't be greater than the inverse square law, right?

The point is that they had to traverse a grav potential where the time dilation was 60,000.
If the grav pot across the planet is bigger than, like, a fraction of 1, then it would be torn apart.
Which means that they would have had to traverse a distance that is 60,000 x some inverse of that fraction x the diameter of the planet.

So, say, a planet falls apart when gravitational potential across the planet's diameter is big enough to cause a time dilation of, say 0.001 from one side to the other. (That's huge, it's probably orders of magnitude smaller).

So, now they must have passed 60,000 x 1000 x the diameter of the planet (let's call it 10,000 miles), for a total distance from Endurance to planet of 600 billion miles. these are just hypothetical numbers, but it's a real problem.

 

[Matterwave]

The point is that they had to traverse a grav potential where the time dilation was 60,000.
If the grav pot across the planet is bigger than, like, a fraction of 1, then it would be torn apart.
Which means that they would have had to traverse a distance that is 60,000 x some inverse of that fraction x the diameter of the planet.

So, say, a planet falls apart when gravitational potential across the planet's diameter is big enough to cause a time dilation of, say 0.001 from one side to the other. (That's huge, it's probably orders of magnitude smaller).

So, now they must have passed 60,000 x 1000 x the diameter of the planet (let's call it 10,000 miles), for a total distance from Endurance to planet of 600 billion miles. these are just hypothetical numbers, but it's a real problem.

Lol, 600 billion miles is well outside of our solar system (I think Neptune is ~1-2 billion miles away from the Sun?)...in what way is that called an "orbit" on the planet? In addition it took Endurance 2 years to reach Saturn, if Endurance was 600 billion miles from the planet, either the shuttle is orders of magnitude faster (then, why not just use the shuttle?) or it would have taken them ~300 years to get to the planet from Endurance, and then 300 years to get back (not counting all of that gravitational potential and time dilation they have to go through).

 

[OmCheeto]

Time dilation wouldn't make a message delayed and then suddenly appear decades later. It would make the message redshifted and slowed down. Even with a factor of 60,000, you could still receive about 1.4 seconds of message per day.

Yes, if anyone were listening for such a dilated message. But didn't Cooper wake up way in the future? My apologies for not being an autistic savant, and not being able to remember every detail in the movie. (I think this was a Hollywood plot also. Us nerds are going to go see it several times, until we figure this out.)

24 hours on the planet equates to 164 Earth years. Now the questions are, how long does that guy's life support hold out, how much time transpired while Cooper was gone, and when does the sequel come out?

 

[DaveC426913]

Lol, 600 billion miles is well outside of our solar system (I think Neptune is ~1-2 billion miles away from the Sun?)...in what way is that called an "orbit" on the planet? In addition it took Endurance 2 years to reach Saturn, if Endurance was 600 billion miles from the planet, either the shuttle is orders of magnitude faster (then, why not just use the shuttle?) or it would have taken them ~300 years to get to the planet from Endurance, and then 300 years to get back (not counting all of that gravitational potential and time dilation they have to go through).

Exactly. This is one "cheat" that can't be handwaved away.

 

[stevebd1]

Parts of 'The Science of Interstellar' are available on Google books. Properties regarding the black hole and Millers planet start about half way down.

 

[hankaaron]

I read a little bit that was made available on Google Books. I'm probably wrong in my assessment but it sounds like Thorne is suggesting that the supermassive swirling black hole is the result of 5th dimensional beings, or constructs, passing through our 3 dimensional universe; and that Prof Brandt realizes it. If not, that would have been a very interesting premise.

 

[dragoneyes001]

has anyone been able to figure out how Cooper learned the trick to overcome gravity while spending his entire time trying to message in the 5th dimension to the third? having all the time he wants doesn't miraculously educate him in new theories.

the other issue is if he can actually manipulate things from the third dimension just how much destruction would the ship he was in cause to it when he let it go off on its own?

 

[DaveC426913]

has anyone been able to figure out how Cooper learned the trick to overcome gravity while spending his entire time trying to message in the 5th dimension to the third? having all the time he wants doesn't miraculously educate him in new theories.

He didn't. TARS did. He had TARS transmit the information to him in binary (presumably, an equation fragment that reconciles relativity with QM).

the other issue is if he can actually manipulate things from the third dimension just how much destruction would the ship he was in cause to it when he let it go off on its own?

There are a thousand ways bad things could have happened on this mission. Lucky they didn't.

 

[dragoneyes001]

[SPOILER ALERT}
it was cooper sending binary to his daughter which if i was following the movie correctly (making the second hand move) which then solved the issue of gravity. prior to the watch she was just as stuck on the equation as the professor

 

[DaveC426913]

[SPOILER ALERT}
it was cooper sending binary to his daughter which if i was following the movie correctly (making the second hand move) which then solved the issue of gravity. prior to the watch she was just as stuck on the equation as the professor

Yes. What is your point?

The question you asked is 'how did Coop learn this?'
The answer is: Coop didn't. TARS did. And sent it to Coop "in binary", as Coop explicitly asked him to.

(My contribution was to presume that the critical information was quite small and relatively simple, possibly an equation fragment.)

 

[dragoneyes001]

I must have missed something along the way.

 

[DaveC426913]

I must have missed something along the way.

A lot of the film's plot happened in very brief moments - like 1 line of dialogue. Very easy to miss. This is part of the film's problem with a lot of its detractors.

 

[dragoneyes001]

yet i still keep thinking the ship careening through the 5th dimension space would do far worse than knock a few books out of line in infinite timelines.

 

[DaveC426913]

yet i still keep thinking the ship careening through the 5th dimension space would do far worse than knock a few books out of line in infinite timelines.

Why do you think that's what happened?

You do recall that the 5 dimensional tesseract was a construct, put there by our future selves. So, not just random events happening there.

Frankly, I don't recall how he actually exited the ship. Did it just go careening off?

 

[DaveC426913]

Cool.

 

[dragoneyes001]

Why do you think that's what happened?

You do recall that the 5 dimensional tesseract was a construct, put there by our future selves. So, not just random events happening there.

Frankly, I don't recall how he actually exited the ship. Did it just go careening off?

he ejected out of it like a jet fighter.

 

[Matterwave]

I just had a thought...the gravitational time dilation of a Schwarzschild black hole (I know Gargantua was a Kerr black hole, but it was said to be rotating very slowly, so I'll use the Schwarzschild approximation) is ##t_o=t_f\sqrt{1-r_s/r}## where ##t_o## is the time as ticked by clocks at radius ##r## from the black hole (i.e. Cooper and Brandt), and ##t_f## is the time as ticked by clocks far away (e.g. Earth), so if you want ##t_f/t_o\approx 60,000## you better have ##r \approx r_s##. Actually, doing the calculation gives ##r\approx 1.00000000028 r_s##. However, there are no orbits there as the photon orbit (the last place a freely falling object, a photon, can still orbit the black hole) is at a radius ##r_p=\frac{3}{2}r_s##.

To get a time dilation factor of 60,000, you have to be well within the photon sphere, where there are no more orbits available...

 

[OmCheeto]

Parts of 'The Science of Interstellar' are available on Google books. Properties regarding the black hole and Millers planet start about half way down.

Yay!

I'm buying that book tomorrow morning.
Some . Only one bad one. (Neb. I checked out his other reviews. I think someone chronically "messes" with his Cheerios.)

I've been reading a lot of reviews of the movie since I've seen it.
One person said the entire thing was a rehash of 2001.
One of the Amazon reviewers said it was a rehash of Contact, and would have been better if it had been more like 2001.

Apparently, we've all witnessed a car crash of a movie. :D

 

[OmCheeto]

Cool.

[monster picture deleted]

Well that was helpful. So Doyle was killed 81 years before Cooper went looking for Amelia. Which by my calculations, means Doyle's body has only been in the water for 12 hours.

Ha!

Back to the real world.
According to wiki; "The longest EVA as of 2007, was 8 hours and 56 minutes, performed by Susan J. Helms and James S. Voss on March 11, 2001."

Let's see. The major complaint about the sequel will be; "Totally predictable."

 

[Rive]

... it was said to be rotating very slowly...

As I recall, it was said to rotate very fast - fast enough to a stable orbit could be so close to the event horizon. Or, at least Phil Plait had to correct his view because of the difference between Schwarzschild/Kerr BHs.

Actually, I think the 'big things' in the movie would be according to the code (general relativity, two body model). Kip Thorne might be a bit carried away with his five-dimension whatever, but even so he is a talented scientist. We can trust him that he did his best with those calculations.

I think we can only hope to catch the movie when it's not a two body model anymore (for example I'm not sure that any stable orbit can exist if there is an accreation disk - the presence of the disk would cause some perturbation, along with some assymetrical radiation pressure: not to mention the radiation itself) or when they had to skip some details in order to go on with the plot (the Δv budget of the shuttle vs. the 60k time dilation factor, discussed previously).

 

[DaveC426913]

he ejected out of it like a jet fighter.

Ah. I see your point.

 

[Matterwave]

As I recall, it was said to rotate very fast - fast enough to a stable orbit could be so close to the event horizon. Or, at least Phil Plait had to correct his view because of the difference between Schwarzschild/Kerr BHs.

Actually, I think the 'big things' in the movie would be according to the code (general relativity, two body model). Kip Thorne might be a bit carried away with his five-dimension whatever, but even so he is a talented scientist. We can trust him that he did his best with those calculations.

I think we can only hope to catch the movie when it's not a two body model anymore (for example I'm not sure that any stable orbit can exist if there is an accreation disk - the presence of the disk would cause some perturbation, along with some assymetrical radiation pressure: not to mention the radiation itself) or when they had to skip some details in order to go on with the plot (the Δv budget of the shuttle vs. the 60k time dilation factor, discussed previously).

If the massive black hole was rotating very fast, then you would have an ergosphere to go along with the event horizon right...wouldn't the planet be inside the ergosphere at that point?

Also, how would a very rapidly rotating supermassive black hole be a "gentle giant" as they say? It seems the frame dragging effects alone would preclude any "gentleness" to this scenario...

 

[dragoneyes001]

Artistic License >/= Gargantuan's Physical time dilation on the surf planet+(plot line)/(editing)= pages of discussion*9

 

[DaveC426913]

A colleague just asked me a couple of questions I couldn't answer:

1] Murph received coordinates by way of the BookShelf-o-Phone, directing them to the NASA launch site. Who sent them? If it was Coop, when did he send them, and where did he get them from?

2] How did he get from the Tesseract in the BH to outside Jupiter? Presumably, OurFutureSelves arranged this - perhaps as some automatic feature of the Tesseract? Is the BH connected to the Jupiter end of the wormhole? Or was he transported directly to an orbit around Jupiter?

2b] I don't trust my memory. I recall something about
- 'OurFutureSelves' can't precisely target a specific spot in spacetime because of their 5D-ness (true),
- which is why Coop was found floating around Jupiter some months or years after the mission completed (true??).
- And it was just lucky they came across him at all, since he might have appeared almost anywhere and anywhen (true??).
Did those last two points occur in the movie, or am I confusing it with comments in post-mortem discussions?

 

[Fredrik]

1. He asked the robot to give him the coordinates, so that he could send them.

2. Yes, "they" did it. I don't think there's any connection between the black hole and the wormhole (because that should have observable effects in and near the wormhole)...but "they" seem to be able to do anything, so they could probably create a connection of they wanted to.

2b. I think he was returned almost immediately after he fell into the black hole. "They" probably just pulled him out of the black hole and then flew him through the wormhole, even though that was never confirmed and he didn't remember anything like that. They (McConaughey and Hathaway) had spent time on the planet, and then more time flying close to the horizon, so many years had passed on Earth even though it didn't seem that way to either of them.

 

[DaveC426913]

A very common theme I am discovering in this film is that, being almost 3 hours long, many plot points are ‘left as an exercise for the student’. :D

 

[Evo]

I hope this hasn't already been posted, seems to be a good review of how bad the movie is.

http://omnifeed.com/article/news.di...tellar-a-missed-opportunity-review-141108.htm