I looked at some of the other smartwatch threads, and being that they were older, they don't cover the following two cases:

  • Hybrid Smartwatches
  • Sports watches

First the assumptions / definitions

  • I assume that you are in agreement that a regular, battery powered watch, with an always on screen is okay to wear on shabbat

  • For this discussion - a "Hybrid Smartwatch" is a regular date/time watch, but has a sensor within it that tracks your steps - this sensor doesn't have a display, and the information is only available to you, if you sync your phone with the watch.

  • A sports watch (for purposes of this discussion) is a watch that has the following features: a) The screen is always on, b) it may have GPS and/or Heart rate measurement - but this only operates when you press a button to go into 'workout' mode, and c)It tracks steps, but doesn't display them on your screen

So now my questions: - Can either of these watches be used on Shabbat? What modifications would need to be made? (or is the fact that they're tracking steps make them prohibited off the cuff)?

-In the case of the Hybrid Smartwatch, would it make a difference if you never sync your phone with it?

  1. Causing changes in electricity is generally prohibited.

  2. So, causing all kinds of electrical activities in the watch purposefully and actively, like waving a hand for changing steps count or pressing buttons or changing screens is prohibited. So any use of watch that intentionally results in minor changes in watch's circuits is bad :(.

  3. Some accept that unintentional and unwanted changes (called לא ניחא ליה) are allowed. For example, taking a solar-powered watch from inside a building to outside is not a problem as long as one is not interested in charging it. Or wearing a step-counting watch for one that's not aware of that function is also allowed under this approach.

  4. Also, any activity that's automatic and autonomic and not user triggered, such as pulse sampling every 5 mins is not a problem just like a regular quartz watch moving its hands.

Another example to clarify the difference - use of GPS tracking (only for the purpose of differentiating the two):

  • if one activates GPS in advance and the watch samples GPS coordinates every second as long as it is autonomous it would not be a problem as the watch works on its own,

  • but if the user enters a building and GPS freaks out - that's is user-generated and is prohibited.

  • 2
    Interesting but without sources, and doesn't answer the key question. Can one wear a watch that captures data the user is interested in (e.g., steps) without intervention, knowing the data will be used after Shabbat. I asked rabbanim and the answer is no but it would be nice to cover it and source it where you can. Also your point 4 might be wrong (in the case where you want and use the data after Shabbat) unless you can source it. – mbloch Nov 9 at 4:51
  • @mbloch You misunderstanding stems from the origin of the data, not the data itself, as I mentioned (maybe not so clear). If the data comes from an activity that's user-generated actively, like waving a hand to activate the motion sensor it is prohibited, but if it is not triggered by the user, even if it monitors him, it is allowed (like periodic HR sampling). Is that more clear now? – Al Berko Nov 9 at 8:10
  • Your opinion is clearer but I am afraid it is wrong. Do you have any sources that passively triggering electric signals to achieve a desirable outcome is permitted ? – mbloch Nov 9 at 9:35
  • @mbloch what do you mean by passively? I only spoke of either actively or autonomously. What example of mine you're referring to. – Al Berko Nov 9 at 10:14
  • I guess your autonomous is my passive. Passively for me means wearing a watch that captures data without interacting with it. Most watches these days count heartbeats and steps without interactions but use the information after Shabbat – mbloch Nov 9 at 10:16

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