Why do people move in slo-mo in space?

Thread Starter

strantor

Joined Oct 3, 2010
5,632
In movies, and in the videos of astronauts in the space station and other space videos, the people always move like they're immersed in water. Everything they do is at sloth speed. Imagine something like shaking a sugar packet... I've never seen a video of an astronaut shaking a sugar packet and I'm not sure it's something that would even need doing in space (do they even have sugar packets? Probably not) but regardless, I can see the action in my head, exaggerated slow movements back and forth, the sugar packet sailing gracefully to and fro as if the video were shot at 120fps.

I understand that without gravity acting against them, prudence would dictate that when relocating their bodies within the vessel, they should move slowly so as to avoid propelling themselves uncontrolled into a sharp corner or something. But it seems every movement, even minor hand gestures, is done as if through a vat of molasses. Why?
 

MrSalts

Joined Apr 2, 2020
523
In movies, and in the videos of astronauts in the space station and other space videos, the people always move like they're immersed in water. Everything they do is at sloth speed. Imagine something like shaking a sugar packet... I've never seen a video of an astronaut shaking a sugar packet and I'm not sure it's something that would even need doing in space (do they even have sugar packets? Probably not) but regardless, I can see the action in my head, exaggerated slow movements back and forth, the sugar packet sailing gracefully to and fro as if the video were shot at 120fps.

I understand that without gravity acting against them, prudence would dictate that when relocating their bodies within the vessel, they should move slowly so as to avoid propelling themselves uncontrolled into a sharp corner or something. But it seems every movement, even minor hand gestures, is done as if through a vat of molasses. Why?
First, sugar doesn’t settle in zero gravity and humidity is well-controlled so there is no need to de-clump he sugar in the packet before opening.

Next, for every action there is an equal and opposite reaction - and - some of those reactive forces are complex torque movements on your body when you move hands or arms quickly. Those torque movements are not expected/learned on earth so your brain cannot quite compensate in real time. instead, of learning how to do that, the brain decides it is easier to minimize the weird/“unpredictable”/“less predictable” torque forces by moving slowly.

Even slow movements can cause your torso to twist away from your task so stabilizing your back to a wall (gently) or feet/thighs to a lab bench helps
 

Thread Starter

strantor

Joined Oct 3, 2010
5,632
First, sugar doesn’t settle in zero gravity and humidity is well-controlled so there is no need to de-clump he sugar in the packet before opening.

Next, for every action there is an equal and opposite reaction - and - some of those reactive forces are complex torque movements on your body when you move hands or arms quickly. Those torque movements are not expected/learned on earth so your brain cannot quite compensate in real time. instead, of learning how to do that, the brain decides it is easier to minimize the weird/“unpredictable”/“less predictable” torque forces by moving slowly.

Even slow movements can cause your torso to twist away from your task so stabilizing your back to a wall (gently) or feet/thighs to a lab bench helps
I suppose the physics make sense; a quick jerk of the arm would effect the whole body, but gravity is so much stronger than those forces that we don't really have to think about it down here, so it's just a little abstract to me. I hadn't considered how disorienting it must be. Now I want to see a child raised in space and see if they move around more like I would expect to see someone move in zero gravity.
 

Delta Prime

Joined Nov 15, 2019
1,147
prudence would dictate that when relocating their bodies within the vessel,
Dear, Prudence. When you're out there in the ether you experience time at a different rate, you age slower as well. You being The observer are experiencing a space-time dilation. Either that or they're just really practicing and overabundance of caution. ;)
 

djsfantasi

Joined Apr 11, 2010
7,825
You mention that you perceive their motions as if they’re moving through water. Perhaps it’s related to the fact that they train in large tanks of water?
 

killivolt

Joined Jan 10, 2010
800
You mention that you perceive their motions as if they’re moving through water. Perhaps it’s related to the fact that they train in large tanks of water?
I really think it’s if move wrong in a small space that is the only thing between you and instant death, compromising your containment vessel might make you move slower. However, in an unlimited non-compromising space would not limit you. Not sure?

kv
 

nsaspook

Joined Aug 27, 2009
8,653
I really think it’s if move wrong in a small space that is the only thing between you and instant death, compromising your containment vessel might make you move slower. However, in an unlimited non-compromising space would not limit you. Not sure?

kv
We normally see 'work' being done in space. The first rule is don't lose your tools so usually people are very deliberate and slow with everything they do. When they're not:

 

MrSalts

Joined Apr 2, 2020
523
I really think it’s if move wrong in a small space that is the only thing between you and instant death, compromising your containment vessel might make you move slower. However, in an unlimited non-compromising space would not limit you. Not sure?

kv
In space, even “unlimited non-compromising spaces” have an end. How would you get traction to slow yourself or divert yourself before hitting the end?
 

killivolt

Joined Jan 10, 2010
800
In space, even “unlimited non-compromising spaces” have an end. How would you get traction to slow yourself or divert yourself before hitting the end?
Not sure how this applies to the Thread, unlimited might have triggered it. But to say bodily movement directly is what I meant to imply. The space to move your limbs around, unlimited space and moving the body through it, different all together. Not sure it’s what the TS meant, I’ll leave it there.

kv
 

MrSalts

Joined Apr 2, 2020
523
The best example is to watch synchronized swimmers - they raise one arm to rotate their torso. The big difference is that, in space, their body wouldn’t stop rotating until a counter motion is made. Or in bumping into something (which would get tiresome).

Note: I’m sure the friction of water is different that the pure kinematic reactions in space but those swimmers can make some really surprising rotations with minimal movements
 
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