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Let's say there's a supermarket selling a hundred different products. Before it opens for the day, the staff arrange all the products into their appropriate shelves. This should be a low entropy state, since the products are highly ordered.

After the supermarket opens, a shopper with a trolley goes in. They select some number of products and put them into the trolley. From the shopper's point of view, it also sounds like this is a low-entropy state - under the definition "stuff I want to buy", all the stuff they want to buy is in that trolley and all the stuff they don't want is outside of it. But from the supermarket's point of view, it should be a higher entropy state; if the shopper leaves, they have to take all the stuff out of the trolley and put them back in the appropriate shelves. Who is correct here?

It seems to me that the problem is that "order" can be defined differently, but that would suggest that entropy itself is not well-defined, and that seems implausible.

Allure
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    It is, or it should be, well-known that the connection between order and entropy is somewhat less simple than in popsci descriptions because there are many possible definitions of order, but not only. A very preliminary question is, Which entropy are we speaking about? ( see for example my answer here: https://physics.stackexchange.com/questions/606722/how-do-different-definitions-of-entropy-connect-with-each-other/606774#606774 ) – GiorgioP-DoomsdayClockIsAt-90 Mar 01 '24 at 05:47
  • This can be analogised with life in universe. Life as we see is highly ordered from our perspective but looking from universe perspective, to maintain the orderness, its casuing even more disorderness in surroundings such that its looks more of disorder than order. – Kshitij Kumar Mar 01 '24 at 06:28
  • If you can keep track of everything that happens there is no entropy change. If information is lost about where the products ended up then entropy increased. – Quillo Mar 01 '24 at 09:01
  • If the supermarket shelves is the system and the supermarket staff the surroundings, one must consider whether or not the work done by the surroundings is reversible to determine the total entropy change of the system plus the surroundings. – Bob D Mar 05 '24 at 15:13

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