GRAVITY -- directed by Alfonso Cuaron

[j1clark@ucsd.edu]

Cuaron had this to say about the untethering scene in an interview with Huffington Post: "What happens is she's grabbing the tethers and he comes with momentum. His momentum pulls her. They're moving together. There's a wide shot that shows they keep moving and you can see the background keeps on moving. What happens is, if he lets go, his force stops and the force of the tether takes over. And, look, by saying that, this is not a documentary. We took certain liberties"
http://m.huffpost.com/us/entry/4018865

Neil deGrasse Tyson was unconvinced though: http://m.huffpost.com/us/entry/40572...=entertainment

In the Tyson tweet he indicates a 'single tug would bring them together'... he seems to ignore the fact that they would 'come together by both moving', and that tug would release Sandra from her tenuous tether to the space craft. So, yeah, they would be together... but just out of reach of the tether to the craft.

[Michael Anthony Horrigan]

In the Tyson tweet he indicates a 'single tug would bring them together'... he seems to ignore the fact that they would 'come together by both moving', and that tug would release Sandra from her tenuous tether to the space craft. So, yeah, they would be together... but just out of reach of the tether to the craft.

How would they "both" come together? She is secured by the strap around her foot, he's just floating in zero G. She wouldn't move.

Anyway, I'm taking his word for it. He's no slouch.

[j1clark@ucsd.edu]

How would they "both" come together? She is secured by the strap around her foot, he's just floating in zero G. She wouldn't move.

Anyway, I'm taking his word for it. He's no slouch.

That's the point. Her attachment to the 'massive' space station is not 'secure', in fact, appears to be just enough to support her own efforts to 'climb back' towards the station.

As Clooney induces a 'force' of tension on his end of the tether, that force will be exerted on the insecure lines on Sandra's boot, causing them to loose their hold, and Sandra will move towards Clooney.

Try it in two boats, one attached to the dock by means of a flimsy line, and another boat further out. As the person on the far boat applies force on a line connecting to the near-dock boat, both boats will move, and tension will be applied to the line connecting to the dock. (There is of course drag of the water on the boat hull, which does not exist in 'space'... but that is negligible in this gedankenexperiment'...)

Even in space 'mass' exists, and 'Force = mass * acceleration'. (On earth Weight = mass * accerlation-of-gravity... 'weightlessness' of course hinges on 'g =~ 0'. But that does not make 'mass' disappear as well...

In the case of the space craft relative to the astronaut, the effect of the force of the astronaut pulling on a tether, that is the F = ma, will have little impact on the mass of the space craft. Which of course is why one can exit the craft, move around, etc. and return by means of the tether. But between two astronauts there will be an effect proportionate to their masses.

[Michael Anthony Horrigan]

I never got the feeling it would happen the way you described. Nor did Tyson, the astrophysicist.
Had Clooney untethered before his force took place on the strap around her foot, I'm right there with you.

But the way it was done in the film, after the fact, meh. It doesn't work.
I'm obviously not the only person who feels this way. The scientific community is all over it.

There are many areas in GRAVITY that throw realism right out the window. But it's just a movie.
I just felt the self sacrifice was unwarranted given their current situation.

Pulled me right out. But only momentarily.

[Michael Anthony Horrigan]

Try it in two boats, one attached to the dock by means of a flimsy line, and another boat further out. As the person on the far boat applies force on a line connecting to the near-dock boat, both boats will move, and tension will be applied to the line connecting to the dock. (There is of course drag of the water on the boat hull, which does not exist in 'space'... but that is negligible in this gedankenexperiment'...)

BTW, this is where I clearly disagree with your hypothesis. The drag of the water when compared to zero gravity is not negligible. Not even close. Just my 2 cents.

There's no real right or wrong when it comes to what happened in the movie. If it worked for you, cool. It just didn't work for me.

Cheers.

[Scott F]

Whew! I finally saw it w/o stumbling upon any spoilers in my day-to-day.

Either way, that scene just doesn't "work" in the movie. Everyone I saw it with had issues with it and it seems like some people here do as well.
It just doesn't work. Took me out of the movie.

And the fact that Cuarón is trying to explain it away isn't a good sign either.

Your quibbling about the whole 'tether' thing seems pretty minor compared to Wesley Bryan's other logistics complaints.

Also, in real life, Hubble and ISS are in completely different orbits. Hubble is much higher up than ISS by hundreds of miles and moving at a different speed along a different path. There would be no way for two astronauts with nothing but a jet pack to make the necessary course corrections to rendezvous with the ISS from Hubble's position. Even under ideal conditions, getting two orbiting spacecraft together is tricky. It's a bit like trying to intercept a bullet with another bullet, and have them gently touch in mid-air. Of course, the only realistic conclusion to the scenario presented in the movie is Bullock and Clooney slowly dying of asphyxiation after the initial accident, which would admittidly make for an unsatisfying movie.

Same problem presents itself with Bullock getting to the Chinese station. It's not quite as much of a stretch there. At least she has a damaged Soyuz, but even a fully functioning Soyuz probably wouldn't be able to make it.

The only way that the premise of this movie could possibly work is if at some point before the movie takes place, for some reason, NASA decided to spend billions of dollars moving the Hubble into an orbit where it rendezvous with the ISS, an orbit in which it not intended to go. On top of that, the Chinese decide to go to similar great effort to position their station within spitting distance of the ISS.

The movie is f-ing rad. See it!

[Michael Anthony Horrigan]

Whew! I finally saw it w/o stumbling upon any spoilers in my day-to-day.
Your quibbling about the whole 'tether' thing seems pretty minor compared to Wesley Bryan's other logistics complaints.

The other logistics didn't take me out of the movie.

[Michael Anthony Horrigan]

The movie is f-ing rad. See it!

Agreed! I plan on seeing it again this week.

[Scott F]

I gotta go back for 3d on round 2.

[capitalP]

Saw it last night in IMAX 3D, like others above, I hate 3D, but this movie worked so well that it did not feel like a 3D movie even though it was if that makes sense. And wow the visuals, amazing, just seeing earth and space like that. I am so curious how they shot this but part of me want it to remain a mystery, if I find out how they shot it, it would somehow ruin the magic for me.

But it was a great movie visually and a good movie dramatically. 3/4 stars.