Eruvin 43 – How high is the techum?

The private area extends above until heaven and below as far as it can go; if one transfers from a public area to it – he is liable. However, public area goes only as high as ten hand-breadths, and higher than this its limitations do not apply. Of course, if one sits on a high pole in a street, he is nevertheless considered to be in the public area, since the pole rests on the ground. However, if one flies in the air, using one of the mystical names of God, do the limitations of techum apply to him? Can he fly beyond two thousand steps? The same question would apply for a ship that is flowing more than ten hand-breadths above the sea floor.

Can we derive the answer from the story of the ship in the sea, where the limitations of techum seemed to apply? – No, because perhaps that ship was in shallow waters. Another story: once seven rulings about terefah were told to Rav Chisda on Shabbat morning in the city of Sura, and on Shabbat afternoon to Rava in the city of Pumbedita. The distance between those two cities is certainly more than two thousand steps, and who could have recited the ruling but Elijah the Prophet, who travels with the help of the names of God!? It must be then that the techum does not extend above ten hand-breadths from the ground! – No, the ruling could have been brought by the well-known demon by the name of Yosef, who does not observe the Shabbat laws anyway, so we cannot learn anything from his behavior.

Art: Viktor Vasnetsov - Flying Carpet