# Would a self-winding watch work in space without gravity?

Could a watch that winds itself with a pendulum work in space with no gravity? Could a pendulum or the self winding part be modified to work off the movements of the wrist in a microgravity environment?

To further this question could a set of various size pendulums be set at different angles to work as mechanical inertia dampeners even to absorb vibrations or microgravity?

https://www.rolex.com/watches/rolex-watchmaking/movements.html

• I think the question's a bit ambiguous... I believe the OP's asking about 'automatic' or self winding watches (judging by the picture. Indeed, these sorts of watches will not wind in a zero gravity environment... – BobT Nov 16 '18 at 23:52
• For those who can see this link: space.stackexchange.com/q/30763/12102 for everyone else, 1, 2 Scott Kelly may know the answer. – uhoh Nov 17 '18 at 1:37
• I think you should change your title to be more direct: "Do self-winding watches wind themselves in space?" – uhoh Nov 17 '18 at 1:40
• @Muze Hey man, you're totally moving in on my turf: worldbuilding.stackexchange.com/questions/129395/… – kingledion Nov 17 '18 at 2:41
• They work in Australia, too. – user3528438 May 10 at 3:49

As long as the wearer moves about, the rotor has no choice but to react to the forces imparted to it. So, yes it would.

• A linear movement of the wearer does not neccessarily turn the rotor of the watch. If the rotor is balanced, a linear movement will never turn it. But starting or stoping a rotation of the wearer in a plane parallel to the rotors plane will turn the rotor. – Uwe May 10 at 10:04

The escapement (the part that actually measures time) uses a spring and balance wheel so it will operate the same way no matter the presence or absence of linear acceleration in any direction. There is no pendulum or other form of eccentric mass involved in this part of the watch.

However, the self-winder is driven by an eccentric mass. It depends on the wearer's movement to turn it. A self-winder I had seemed to wind most efficiently in response to the natural back-and-forth movement of the wearer's arm while walking. It would also wind if held face-up and swung from side-to-side. What can be inferred from this is that the presence of gravity does nothing to help the self-winding action, and may inhibit it from working in some situations.

So, yes, any self-winding watch should work just fine in zero gravity, as long as it experiences some back-and forth movement.