On earth the rule is that תתאה גבר, if kosher and not kosher mix in a hot application, it depends which is “תתאה” bottom. If the hot is bottom it’s all forbidden, if the top is hot than it’s only forbidden through the “peel”. How does the rule of תתאה גבר apply in deep space where there effectively 0 gravity. If I had a hot piece of meat floating stationary in space and shook a pot of cold milk at it. Is the meat considered תתאה and so it’s totally forbidden or is the milk and so you would only have to remove a “peel”? Or is there some third option? sefaria link to rule of תתאה גבר
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How do you define top and bottom in space?– robevCommented Dec 23, 2020 at 13:01
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Might be relevant is the Issur VeHeter I believe says תתאי גבר works by the top one weighing down on the bottom, which probably doesn't happen in space– robevCommented Dec 23, 2020 at 13:02
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The basic defnintion of "top and bottom" in earth orbit would be bottom is toward the earth, top is away from the earth. But once you leave earth orbit, that definition will change. When on the moon, you would have the effects of moon's gravity and bottom would be toward the moon, top away from the moon. Keep in mind, even in earth orbit where gravity appears to be zero, you are still in the earth's gravitational field. Also, keep in mind you can simulate the effects of earth's gravity in space by use of a centrifuge. Just saying, it is not that simple a question.– DennisCommented Dec 23, 2020 at 16:13
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@Dennis 1) what about if you had a centrifugal cooker which you had meat spinning g around in. And then at an exact moment where the meat was pointed up towards the sky you squirted milk at it?– mrollCommented Dec 23, 2020 at 19:31
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1@Dennis I specifically said deep space in my question to avoid the whole relative gravity issue.– mrollCommented Dec 23, 2020 at 19:32
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1 Answer
From my understanding, תתאה גבר is not necessarily the one that is on the bottom, even though that's what the words literally mean. It is more the vessel that was poured FROM to the vessel it is poured INTO.
According to Tosfot in Shabbos 145, it says that the whole point of a Kli Sheini (Kli Sheini is relevant because the Rashbam learns that עירוי כלי ראשון is considered Kli Sheini from the Gemara in Pesachim that talks about תתאה גבר.) is that it reaches the walls of the cooler vessel and cools off the liquid. (Only a liquid as opposed to a solid - דבר גוש because a solid does not fill the shape of the Kli Sheini vessel in order to touch the walls and cool down. (ש״ך/ביאור הגר״א quoting the ים של שלמה)
As for in space, I don't know how it would work. Would the liquid even fill the entire vessel and touch the walls at all? It probably wouldn't even leave the first vessel unless you pushed it somehow into the second vessel. Would heat dissipate the same way in space as it does on earth?
All valid questions. It's very interesting to think of.
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There are cases which aren't covered by the above: תתאה גבר is applied to melicha according to some, see Aruch Hashulchan 70:27 & Siftei Daat 70:22, which gives a case that says if a treif piece and a kosher piece are salted while touching, and one of them is fatty, the kosher piece is assur until 60 (as opposed to assur kdei klipa) only if it tafel and is on the top, not side by side or on the bottom. Seems like for this case at least, we need a well defined bottom, and that doesn't exist in space Commented Mar 5 at 23:11