Gravity

[Khev]

Just saw this last night. By FAR the best movie I've seen this year. Hell it may be one of the best of the last decade.

 

[GasparZizou]

I agree with your assessment, and I can't wait to see it a third (and forth) time. But this is not a Sci-Fi movie. At all.

Mhmm I don't know, I think it is sci fi, the mere fact that there's a debris cloud orbiting earth makes it sci fi.

I want to see it again, this time in 3D.

From the reading I have done, it seems that the only justification for him being pulled away is centripetal force caused by them traveling in a large arc with the spot where the straps were caught being a pivot point. However, even after watching it a second time it really just looks like he is being pulled by magic. The "arc" is not at all obvious, if it even exists at all.


To be clear, I think Kowalski needed to die for the plot to come home, I just think that scene should have made what was happening more clear.

The centripetal force should have made Matt do the whole arc back to the Russian station, the centripetal force pulls you inside not outside of the arc, centrifugal force is the one that pulls you out, but it's a fictitious force, it's really just tangential inertia, and since by catching him, Ryan instantly cancelled the centrifugal force (inertia), then there was nothing pulling him away, there's really no explanation for that, it's straight up an error, I agree, Matt should have died, it's just that they missed that spot in the "how".

My way of fixing that would be:

When Ryan catches Matt, both realise that there's a big chunk of the Russian station tangled to Matt's maneuvering unit by a wire or something, slowly moving away from both, so if Matt doesn't let go, the wire is going to tense up, pulling both away.... .

 

[GasparZizou]

Just saw this last night. By FAR the best movie I've seen this year. Hell it may be one of the best of the last decade.

I agree completely, you know that thing they call "book hangover"? Well I'm still drunk of this movie and it has lasted 2 hours now...

 

[tylerdurden]

My way of fixing that would be:

When Ryan catches Matt, both realise that there's a big chunk of the Russian station tangled to Matt's maneuvering unit by a wire or something, slowly moving away from both, so if Matt doesn't let go, the wire is going to tense up, pulling both away.... .

that's a pretty solid explanation. i had something similar in mind --- kowalski's hit by some debris, which creates the outward force away from dr. stone. and since the debris damages his spacesuit, he knows he's screwed anyway, so he asks stone to let him go...

btw, here's a pretty good review on the film:
https://electroshadow.com/?p=24467

 

[Maglor]

Mhmm I don't know, I think it is sci fi, the mere fact that there's a debris cloud orbiting earth makes it sci fi.

That makes it fiction.

I'll be crucified if I carry on with this argument. People got sick of it already.

If you want to know my thoughts, I have several lengthy posts in this thread about it.

The centripetal force should have made Matt do the whole arc back to the Russian station, the centripetal force pulls you inside not outside of the arc, centrifugal force is the one that pulls you out, but it's a fictitious force, it's really just tangential inertia, and since by catching him, Ryan instantly cancelled the centrifugal force (inertia), then there was nothing pulling him away, there's really no explanation for that, it's straight up an error, I agree, Matt should have died, it's just that they missed that spot in the "how".

Dang it! I thought I had fixed the post to say centrifugal force!

That's what I meant. (Fixed the post.)

If they were both traveling in a huge arc then there would indeed be outward inertia. If you tied a rock to a rope and swung it around, there would be outward inertia. Or think of a tether ball swinging around a pole.

My way of fixing that would be:

When Ryan catches Matt, both realise that there's a big chunk of the Russian station tangled to Matt's maneuvering unit by a wire or something, slowly moving away from both, so if Matt doesn't let go, the wire is going to tense up, pulling both away.... .

I don't get it. But the arc thing works anyway. And some say that the arc is indeed present on screen. As Matt disconnects, you can supposedly see the stars moving behind him implying the arc.

Also, you keep talking about a Russian station. Wasn't it the ISS? Is the ISS a Russian station? I just remember them referring to it as the ISS.

 

[GasparZizou]

That makes it fiction.

I'll be crucified if I carry on with this argument. People got sick of it already.

If you want to know my thoughts, I have several lengthy posts in this thread about it.

I'm convinced it's sci-fi, there are many elements of this movie that make it sci-fi, even the maneuvering unit that Matt gave compliments to engineering for, it has the fuel capacity for Matt to rescue Ryan and make a trip to the Soyuz, the real maneuvering units wouldn't even have the fuel capacity to be able to make the trip to save Ryan when she was drifting.

Dang it! I thought I had fixed the post to say centrifugal force!

That's what I meant. (Fixed the post.)

If they were both traveling in a huge arc then there would indeed be outward inertia. If you tied a rock to a rope and swung it around, there would be outward inertia. Or think of a tether ball swinging around a pole.

I don't get it. But the arc thing works anyway. And some say that the arc is indeed present on screen. As Matt disconnects, you can supposedly see the stars moving behind him implying the arc.

Now that I think about it, I don't think there was ever such arc, but it's irrelevant, yes, there WAS tangential inertia, but Ryan stopped it instantly by catching Matt, she reduced his speed to zero, there's no acceleration in space, only earths gravitational pull, and Matt didn't go downstairs, he stayed on orbit, so, no other forces acting on him, so, when you have a certain speed, it will remain constant, as well as when you have an object in a state of repose, Matt passed from having a speed to not having any speed and that's the way he should have remained, there was nothing pulling him away.

I could post all sorts of diagrams but I won't, because it's lame

Maybe a the ghost from Paranormal Activity was pulling his feet? :

Also, you keep talking about a Russian station. Wasn't it the ISS? Is the ISS a Russian station? I just remember them referring to it as the ISS.

Well, it was called Soyuz, the keyboard was Russian, and there was vodka! what else do you want?

What does ISS stand for? International Space Station? Then I guess it was international, but still, Russian keyboard and vodka?

 

[Maglor]

I'm convinced it's sci-fi, there are many elements of this movie that make it sci-fi, even the maneuvering unit that Matt gave compliments to engineering for, it has the fuel capacity for Matt to rescue Ryan and make a trip to the Soyuz, the real maneuvering units wouldn't even have the fuel capacity to be able to make the trip to save Ryan when she was drifting.

All generes break the rules a bit. Especially if they're action movies.

What about a movie with cowboys shooting more than 6 times without needing to reload? Does that automatically become Sci-Fi because it's not 100% realistic? No, it's supposed to be believable, and you're just not supposed to notice that detail. You suspend disbelief in order to allow the story to progress.

Science Fiction is a totally different animal. It uses clearly speculative/fictional science as a vehicle. Things like time travel, aliens, artificial intelligence, and deep space travel. All things that may some day be possible (unlike Fantasy), but currently are not.


Part of what makes this film so special is that it is the first fictional, yet reality based, Space movie that we have ever seen.

I say this as a fan of Science Fiction: To call Gravity Science Fiction (or even worse, "Sci-Fi") marginalizes it, and is misleading to potential viewers.

Now that I think about it, I don't think there was ever such arc, but it's irrelevant, yes, there WAS tangential inertia, but Ryan stopped it instantly by catching Matt, she reduced his speed to zero, there's no acceleration in space, only earths gravitational pull, and Matt didn't go downstairs, he stayed on orbit, so, no other forces acting on him, so, when you have a certain speed, it will remain constant, as well as when you have an object in a state of repose, Matt passed from having a speed to not having any speed and that's the way he should have remained, there was nothing pulling him away.

I could post all sorts of diagrams but I won't, because it's lame

Maybe a the ghost from Paranormal Activity was pulling his feet?

It really does look like that.

Here's a post about it from IMDB. [This guy is kind of a ******, but he's very outspoken in favor of this scene]:

you have three things.

1) An Anchor point (where the shroud lines are attached to the station)
2) A line of a fixed length (In this case the shroud lines she gets tangled in)
3) A weight on the end of the line (in this case the astronaut)

If you were to throw the weight directly out from the anchor point, when the weight reaches the limit of the line's length, the line snaps tight and exerts centripetal force directly back to the anchor point. The weight will stop and any elasticity in the line will cause the weight to spring directly back towards the anchor point.
That is because the inertia of the weight is directly opposed by the centripetal force of the line.
You see this later in the film as she is trying to back the Soyuz capsule directly away from the station.

But that's not what happens with her earlier.

Now take your weight and rather than throwing it out directly away from the anchor point, stand to one side and throw the weight past the anchor point. What happens now?

The weight moves past the anchor point and continues in a straight line until it once again reaches the end of the line. Once again centripetal force is applied to the object in a vector DIRECTLY BACK TOWARDS THE ANCHOR. But the weight's inertia IS NOT DIRECTLY AWAY FROM THE ANCHOR.

So Centripetal force is not acting in direct opposition to the weight's inertia but at an ANGLE to it. This imparts angular momentum to the weight and starts the astronaut swinging in an arc about the station. Like a Tetherball in it's string about the pole.

A Ground based example:
Tie a rope in a tree on a branch and from a point directly at the rope, drop a weight tied to the rope. The weight falls til the rope reaches it's length and stops the weight. Nothing more happens. The weight stops where it is.
(in reality, minor forces will act upon it such as the give of the branch and elasticity of the rope to cause the weight to bounce, minor variations in dropping the weight will cause it to jerk slightly to one side or the other, but for all practical purposes, the weight stops where it is)

Now climb over to another branch off to one side of the anchoring branch and again drop the weight. This time as the weight reaches the end of the rope it starts swinging. the direction of swing will be directly towards the the point underneath the anchoring branch.

Now do you understand?

by - CGSailor

Thread link: https://www.imdb.com/title/tt1454468/board/thread/220668860?p=1

I really want him to be right. It's the only flaw I see in an otherwise perfect movie.

Well, it was called Soyuz, the keyboard was Russian, and there was vodka! what else do you want?

What does ISS stand for? International Space Station? Then I guess it was international, but still, Russian keyboard and vodka?

Yep, "International Space Station". I guess I'm being pedantic, but I don't recall it being referred to as a "Russian station".

Might be my ignorance though. Perhaps it's common knowledge that it's "international" in name only, and really is a Russian station.

 

[GasparZizou]

All generes break the rules a bit. Especially if they're action movies.

What about a movie with cowboys shooting more than 6 times without needing to reload? Does that automatically become Sci-Fi because it's not 100% realistic? No, it's supposed to be believable, and you're just not supposed to notice that detail. You suspend disbelief in order to allow the story to progress.

Science Fiction is a totally different animal. It uses clearly speculative/fictional science as a vehicle. Things like time travel, aliens, artificial intelligence, and deep space travel. All things that may some day be possible (unlike Fantasy), but currently are not.

Part of what makes this film so special is that it is the first fictional, yet reality based, Space movie that we have ever seen.

I say this as a fan of Science Fiction: To call Gravity Science Fiction (or even worse, "Sci-Fi") marginalizes it, and is misleading to potential viewers.

They're not breaking any rules as long as they address the issue which they do, it doesn't need time travel nor cloning or robots to be sci-fi, it's not star wars sci-fi, but it is indeed sci-fi, in fact this is the definition of sci-fi, when most movies stretch a lot into sci-fantasy.

It really does look like that.

Here's a post about it from IMDB. [This guy is kind of a ******, but he's very outspoken in favor of this scene]:Thread link: https://www.imdb.com/title/tt1454468/board/thread/220668860?p=1

I really want him to be right. It's the only flaw I see in an otherwise perfect movie.

Yeah I just checked the IMDB boards and they're awful! Lots of movie snobs that just jaded and apparently hate movies.

He's wrong though, there's no weight on that equation, weight is given by a gravitational pull, otherwise is just mass, hence why you cannot use any "ground" examples because the gravitational pull will continue to generate an acceleration, hence why if you hang something from a rope (anchor) the acceleration (gravity) will pull it down, generating a weight which will tense up the rope.

But in space there's no acceleration nor gravity, ergo, no weight, once you stop something that's in movement it remains still, all forces change from dynamic equilibrium to static equilibrium because there aren't any more forces, speeds, masses and definitely not a single acceleration, it's just an error, it's not really a discussion if you stick to Newton's laws, it's pretty clear to me.

Classics are no 100% perfect, but it doesn't detract from the movie, while this is an error in the movie, it doesn't detract from the overall experience, it's an easy fix really, but an error nonetheless.

We should be happy that this is the only real problem with the movie when most movies are just plagued by inconsistencies, even more, recent movies.

In fact, this movie should win the oscar for "Less times the laws of physics have been broken in a movie EVER" with a total count of 2, even TV shows break those laws left and right

Yep, "International Space Station". I guess I'm being pedantic, but I don't recall it being referred to as a "Russian station".

Might be my ignorance though. Perhaps it's common knowledge that it's "international" in name only, and really is a Russian station.

Nah, it's ok, I just said it was Russian cause it was easy for me to remember, American, Russian, Chinese I don't really know the nomenclature for Space ships.

 

[Maglor]

They're not breaking any rules as long as they address the issue which they do...

Who does? Westerns? We never get an explanation for why they don't need to unload their 6 shooters. And we don't want one. Rules of science and physics get broken in every Bond movie, every Mission Impossible movie, with no explanation. It's just something that we overlook when being entertained.

...it doesn't need time travel nor cloning or robots to be sci-fi, it's not star wars sci-fi, but it is indeed sci-fi, in fact this is the definition of sci-fi, when most movies stretch a lot into sci-fantasy.

Star Wars is Science Fantasy. I would almost go so far as to say, straight up Fantasy.

iRobot is Science Fiction.

Gravity is a Survival Film set in space.

Apollo 13 is a Survival Film set in space.

The only difference between Apollo 13 and Gravity is that Gravity is fiction and Apollo 13 is historical fiction.


The qualifications for science fiction aren't 'fiction with science in it'. If that were true, Breaking Bad would be Science Fiction.

Without overtly fictional science, it's not science fiction.

Yeah I just checked the IMDB boards and they're awful! Lots of movie snobs that just jaded and apparently hate movies.

Yeah, IMDB is pretty awful.

He's wrong though, there's no weight on that equation, weight is given by a gravitational pull, otherwise is just mass, hence why you cannot use any "ground" examples because the gravitational pull will continue to generate an acceleration, hence why if you hang something from a rope (anchor) the acceleration (gravity) will pull it down, generating a weight which will tense up the rope.

But in space there's no acceleration nor gravity, ergo, no weight, once you stop something that's in movement it remains still, all forces change from dynamic equilibrium to static equilibrium because there aren't any more forces, speeds, masses and definitely not a single acceleration, it's just an error, it's not really a discussion if you stick to Newton's laws, it's pretty clear to me.

So you're saying that if you tied a brick to the end of a rope in space, and then swung it around that the brick wouldn't pull the rope taught and swing around? What, it would just flop about randomly?

There is no gravity in space, but things still have weight. And the laws of physics are the same.

 

[GasparZizou]

Who does? Westerns? We never get an explanation for why they don't need to unload their 6 shooters. And we don't want one. Rules of science and physics get broken in every Bond movie, every Mission Impossible movie, with no explanation. It's just something that we overlook when being entertained.

No, I meant gravity, gravity explains the reason why they can travel so long distances with the maneuvering units, because they're improved, scientific improvements like those that don't exist yet make this movie sci-fi, this isn't just a movie with science foundations, it definitely qualifies as sci-fi.

So you're saying that if you tied a brick to the end of a rope in space, and then swung it around that the brick wouldn't pull the rope taught and swing around? What, it would just flop about randomly?

There is no gravity in space, but things still have weight. And the laws of physics are the same.

No, I'm saying that if you tied a brick to a rope and throw in space, the brick would indeed pull the rope momentarily , as soon as the rope tenses, depending of the speed of the brick, it either stops right there, or comes back, but it will not keep pulling.

Now if you mean thrown in an "arc" it would still be pulling but completing the circle, not continue to pull outside, that scene had no arc, otherwise when the cable was completely tense, Matt would had continue to travel in a circular trajectory around Ryan, back to the Soyuz, and he didn't, he was "pulling away", it was minuscule and the pull from Ryan would have either stopped Matt or bring him closer, not keep pulling him away.

Things have no weight in space, you're confusing weight with mass, weight is the product of the mass times gravity (or any acceleration), since there's no gravity nor acceleration, there's no weight.

 

[Maglor]

No, I meant gravity, gravity explains the reason why they can travel so long distances with the maneuvering units, because they're improved, scientific improvements like those that don't exist yet make this movie sci-fi, this isn't just a movie with science foundations, it definitely qualifies as sci-fi.

This is the first plausible argument I have seen for the movie being Science Fiction.

That said, I have seen it twice and did not get the impression that the audience was meant to recognize anything in the movie as fictional science. If anything the science is dated. The shuttle program is no more, and my understanding is that the jet pack is old tech.

I don't remember much about the explanation you are referring to, but I will pay closer attention on future viewings.

In the end, even if they stretched the abilities of the jet pack, I still don't see that one detail as being enough to justify calling it Sci-Fi. Everyone who sees it assumes the technology presented exists. That is the film makers intent, and only you and a few others would know otherwise.

No, I'm saying that if you tied a brick to a rope and throw in space, the brick would indeed pull the rope momentarily , as soon as the rope tenses, depending of the speed of the brick, it either stops right there, or comes back, but it will not keep pulling.

This is obvious. I have said nothing to contradict this. This is the whole reason why the scene looks weird. The post I quoted from IMDB said that if she were propelled straight out from the anchor point, she would simply bounce back when the ropes became taught. I'm confused as to why you would even bother to mention this.

Now if you mean thrown in an "arc"...

Yes, I mean thrown in an arc. I've said it repeatedly. It's the whole point of the post I quoted from IMDB. And it's the only possible explanation for what was on screen.

Now if you mean thrown in an "arc" it would still be pulling but completing the circle, not continue to pull outside...

Yes it would eventually complete a circle, like a tether ball around a pole. But the theory is a that it's a very large arc, and Matt disconnects before she can begin wrapping around the ISS.

...that scene had no arc, otherwise when the cable was completely tense, Matt would had continue to travel in a circular trajectory around Ryan, back to the Soyuz, and he didn't, he was "pulling away", it was minuscule and the pull from Ryan would have either stopped Matt or bring him closer, not keep pulling him away.

I have no idea where you get that. He wasn't raveling in an arc around her, they were traveling together in the arc. Being farthest from the pivot point Matt would be traveling the fastest and would be "pulled" away from her when detaching - as in fact happens on screen.

The only question is: were they really traveling in an arc? As I have mentioned, supposedly you can see the stars moving behind Matt as he detaches, which would certainly support the theory.

I have a hard time believing that the film makers didn't think this through, and that they would really intend for it to be magic pulling him away. They must have intended to convey an arc, as it's the only thing that justifies what we see on screen. They just executed it poorly.

Shame, because it kind of spoils the emotional impact of the scene.

 

[Maglor]

The biggest problem I have with the "arc theory" is that after Matt disconnects, the straps wrapped attached to Ryan's foot suddenly go slack. The outward momentum wouldn't have just been eliminated instantly like that.

 

[GasparZizou]

When she grabbed a hold of the ISS, she became the pivotal point, hence why Matt would travel around her, if there was even the slightest arc.

Yeah, from my still fresh memory, there's no noticeable arc, if it was an arc he wouldn't be pulling away while they're both clearly still, nor Matt's trajectory when he detaches indicates that there was an arc.

I didn't notice that, you're right, he wouldn't have been able to even detach from Ryan since the wire was all tense

Maybe they can call Lucas so he can fix that scene with a little something? Maybe throw a "nooooo" into the mix?

 

[Maglor]

When she grabbed a hold of the ISS, she became the pivotal point, hence why Matt would travel around her, if there was even the slightest arc.

I'm still not following what you're saying about Matt traveling in his own arc. Ryan was not the pivot point, the ISS was - and they were arcing around it together. Again, that's the only possible explanation for what we see on screen.

The thread I linked goes into great detail about this. There is nothing to imply that Ryan is the pivot point. She couldn't be unless she was at a fixed point, which she was not.


What I'm thinking is that she was traveling in an arc around the station, then Matt was added to the same arc which increased the momentum. He needed to detach because that added momentum was too much for the strap around her ankle. But that still doesn't explain why her momentum completely dissipated when he detached...

Yeah, from my still fresh memory, there's no noticeable arc, if it was an arc he wouldn't be pulling away while they're both clearly still, nor Matt's trajectory when he detaches indicates that there was an arc.

It does give that impression, but how do you account for the stars moving behind Matt?

 

[GasparZizou]

Yeah, the ISS is the pivotal point, sorry, I forgot her foot was tangled and she wasn't grabbing anything but Matt's wire, still, they clearly were not moving on an arc.

Again, there's no acceleration, it's space, since there's no acceleration, when she got tangled with the ISS she's gonna stop, which she did, then when Matt is added, he should've stopped as well, I can't make it any more clear.

The momentum is changed instantly, not gradually, if they were going to be pulled away, they should have been pulled away from the moment she reached up and caught Matt, but once she catches Matt the "momentum" disappears and the inertia changes from dynamic, to static, there's not a single force acting on them, arc or no arc, there was no reason for Matt to let go.

 

[Maglor]

Not sure where the disconnect is here.

I'm trying to figure out what you're saying about the difference between earth and space, and the way physics work in each environment...


Let's say you have a tether ball on earth. You give it a throw and it spins around the pivot point. But it also slows down and is pulled downward towards the earth.

Now do the same thing in space. You give it a throw and now you don't have gravity. The ball doesn't slow down in the same way and it won't be pulled downward. But it still spins around the pivot point, right?

Now add length of rope to the end of the tether ball and attach a second tether ball (representing Kowalski). The first tether ball closer to the pole might still be traveling at the same speed it was before the second ball was added, but the second ball will be traveling faster (relative to the first ball) because it has a wider "orbit", so to speak.


If you watch the trailer you can see Ryan moving very fast at an angle to the ISS that could easily start the tether ball arc when the straps become taught. Depending on Matt's trajectory, it seems plausible to me that he could have become the second tether ball in my example. He wouldn't necessarily stop her short.

You keep saying 'they clearly were not moving in an arc', but why do you say this? Do you think the film makers would agree? I can't think of any justification they might use for Matt being pulled away other than the outward momentum of such a motion.

What are your thoughts on why the stars are spinning behind Kowalski, if they are clearly not moving in an arc?


To be clear, I'm sort of playing devils advocate here because I want the arc theory to be true so badly as it would take away the one flaw I see in the film. But I have to admit the wide shot of Ryan and Matt all stretched out at the end of their tethers sure gives the impression that they are just hanging there in space. Maybe, just maybe though, that was a case of artistic license to get a stunning shot, while the actual event portrayed was them moving in a relatively slow, but fast enough arc to justify Kowalski's death...

 

[GasparZizou]

I completely understand your point, I see you want to believe it's not an error we've all been there, but even if this remains unexplained or catalogued as an error, it's still the instant classic I think it is.

The tetherball example doesn't work here, because, again there's no acceleration, let's say they are in fact moving in an arc, the arc is going to go all the way back to the ISS, but since there's no more acceleration, there isn't any extra tension provided, hence why there's no reason to detach.

I'm basing on 2 things mainly, to say they're not traveling in an arc:

1) The camera is moving all the time which makes it seem that they are the ones moving and not the camera, I might be wrong on this one.

2) And this is the litmus test IMO, if they were traveling in an arc, when Matt detached, his trajectory would be tangential to the arc, and it clearly isn't, it just goes away....

Here's a diagram to show this: https://www.ux1.eiu.edu/~cfadd/1150/03Vct2D/Images/tang1.gif

If they were travelling in an arc, Matt's trajectory would be comparable to the red arrows, but he seems to have the same trajectory as the blue arrows.

 

[Maglor]

Thanks for the diagram. It gives us a point of reference.

I agree with you that if they were traveling in an arc, he would travel on the red arrows. The thing is, we see him detach from Ryan's point of view. She would still be in motion, so the perception from the camera would be that he is moving away in a straight line.

Again, what do you say to the moving stars behind Matt?

 

[Maglor]

The tetherball example doesn't work here, because, again there's no acceleration, let's say they are in fact moving in an arc, the arc is going to go all the way back to the ISS, but since there's no more acceleration, there isn't any extra tension provided, hence why there's no reason to detach.

Perhaps acceleration is the wrong word.

All I know is that if I swing a rope in a circle with two bricks tied to the end, I'm more likely to loose my grip than I would with only one brick tied to the end.

 

[GasparZizou]

Thanks for the diagram. It gives us a point of reference.

I agree with you that if they were traveling in an arc, he would travel on the red arrows. The thing is, we see him detach from Ryan's point of view. She would still be in motion, so the perception from the camera would be that he is moving away in a straight line.

Again, what do you say to the moving stars behind Matt?

No problem.

Actually, when Matt let go, from her point of view, the tangential trajectory would still be noticeable and he would go out of her field of vision.

The moving stars behind Matt I'd say it's because the camera, but I can't find the trailer, well, I'm gonna watch it again tomorrow anyway

Those debris rain sequences are so freaking unsettling, I love them!