Okay, so I was browsing some watch forums the other day, and this question popped up: “Do mechanical watches have time dilation?” It kinda blew my mind a little. I mean, I know a bit about Einstein’s theory of relativity, but I’d never really thought about it applying to my trusty old Seiko!

So, I decided to do a little digging. And, let me tell you, it got a bit nerdy, but it was also super interesting.
My Little Experiment
First, I grabbed two of my mechanical watches. One is an automatic, you know, the kind that winds itself with the movement of your wrist. The other is a manual wind, the old-fashioned type you have to wind up yourself.
I synchronized both watches to the atomic clock online. Yeah, I know, pretty precise, right? Then, I strapped the automatic to my wrist and just went about my day. The manual wind one, I just left it on my desk.
- Step 1: Get two mechanical watches (one automatic, one manual).
- Step 2: Sync them up with an atomic clock.
- Step 3: Wear the automatic, leave the manual one stationary.
I wore the automatic for about 24 hours. I figured that would be enough time for, you know, science to happen. I mean, I wasn’t exactly running around at the speed of light, but still, movement is movement, right?
After 24 hours, I took the automatic off and compared it to the manual wind one, and then back to the atomic clock online.

The “Results” (Kinda)
Honestly? Both watches were pretty much still in sync. Maybe a second or two off from each other, and from the atomic clock, but that’s normal for mechanical watches. They aren’t perfect timekeepers, they gain or lose a few seconds per day anyway.
So, did I prove anything about time dilation? Not really. My little experiment was way too crude. To actually see any noticeable time dilation from movement, I’d need to be moving much faster, like, close to the speed of light. That’s not happening anytime soon!
I think, yeah my conclusion is, the effect on a wristwatch is too small to notice. But it’s still pretty cool to think about!