Does One Who Flies on Saturday Night Need to Keep Shabbat Again?
How should an observant Jew from Israel who flies to New York on Saturday night, where it's still Shabbat, conduct themselves? And why isn't Shabbat observed simultaneously worldwide? A fascinating halakhic exploration from the Talmud.
Due to the spherical shape of our world, the sun does not illuminate the entire Earth at the same time. Therefore, when the sun is blazing in the Land of Israel, complete darkness prevails in other places, and vice versa. This fact raises a question that many scholars have grappled with, as attested by the Radbaz: Since resting on the seventh day commemorates the Creation—Hashem's rest from creating the world—shouldn't the entire world observe Shabbat simultaneously? For example, shouldn't the whole world observe Shabbat according to the sunset and sunrise times at Marah, where the Children of Israel were first commanded about Shabbat?
Shabbat is unique for each Jew: The Radbaz (Responsa Vol. 1, Ch. 76) explains that this question assumes Shabbat is a general day of rest for the entire world. However, the truth is that Shabbat is unique for each Jew according to their location, as Shabbat is "a sign between Me and you." Therefore, every Jew must observe, in their current location, the sign and symbol that Hashem commanded. In other words, Shabbat is the seventh day following six days of work. In each place, people count six workdays according to the count of the six days of Creation and rest on the seventh day.
Why is a gentile who observes Shabbat on Monday liable for death? The Radbaz finds support for his explanation in our Talmudic passage, which states that a gentile who observes Shabbat is liable for death even if he rests on Monday. What does Shabbat have to do with Monday? The answer is that Shabbat is the seventh day after six workdays, to the extent that if a gentile works for six consecutive days and rests on the seventh, he is considered to have observed Shabbat and is liable for death, even if it's Monday! The Radbaz finds further support in the Talmud (Shabbat 69b), which states that someone lost in the desert who loses track of days "counts six days and sanctifies the seventh." Again, this proves that Shabbat was given to each Jew individually, wherever they are, and is not a universal day of rest that descended upon the entire world [In our study hall, it was noted that Rashi and Ran explain that this rule of counting six days and sanctifying the seventh is rabbinic, a commemoration of Shabbat. According to this, it's not relevant to our discussion, which concerns the fundamental law].
"And on the seventh day He rested" - but not simultaneously everywhere: The Maharit ("Tzafnat Paneach") addresses this issue differently. According to him, the process of Creation did not occur simultaneously everywhere. When Hashem said, "Let the earth bring forth grass," the earth began to sprout grass from a certain place, and the process continued throughout the world over twenty-four continuous hours until grass grew worldwide. In other words, Creation itself did not happen in an instant but in each place according to its own time. The Chatam Sofer wrote similarly, adding that Hashem's rest on the seventh day was not simultaneous everywhere; rather, in each place, creation ceased when the sixth day ended. Therefore, just as Hashem rested on the seventh day in each place according to its time, so too the commandment of Shabbat was given for each place according to its time (cited in Responsa "Mishpetei Uziel" Orach Chaim 29).
If we were to briefly summarize the difference between the Radbaz's explanation and those of the Maharit and Chatam Sofer, we could formulate it as follows: Everyone agrees that every Jew is commanded to observe Shabbat on the seventh day that occurs in their location. The question is from where this obligation to rest derives. According to the Radbaz, the obligation exists because every Jew is commanded to rest, and the time of this commandment is determined by their location. According to the Maharit and Chatam Sofer, the obligation to rest stems from the fact that the seventh day is occurring in their location. In other words, their location compels them, and is not merely a means of defining the times of the commandment.
A Jew from Israel who flies to New York after Havdalah while it's still Shabbat there: In recent generations, an interesting question has arisen: How should a Jew from Israel who performs Havdalah at the end of Shabbat, boards a Concorde aircraft, and lands in New York on Shabbat afternoon conduct themselves? On one hand, they have already fulfilled the mitzvah of Shabbat this week. On the other hand, in their current location, the seventh day requiring rest from work is in effect. Later authorities have discussed this dilemma, and in its aspects, we also find the difference between the explanations of the Radbaz and those of the Maharit and Chatam Sofer mentioned above. According to the Maharit and Chatam Sofer, a Jew's obligation to observe Shabbat stems from the fact that the seventh day—when Hashem rested from all work—is occurring in their location. Therefore, in any place where the seventh day occurs, Jews are obligated to rest, even if they previously observed Shabbat elsewhere. Conversely, according to the Radbaz, Shabbat was given to each Jew individually, and a divine command instructs the Jew to rest one day each week. Therefore, a Jew who has already observed Shabbat this week and fulfilled this mitzvah does not need to—and will not fulfill a commandment if they do—observe it again. It should be noted that this discussion concerns biblical law only, but according to rabbinic law, all opinions agree that one should act stringently according to the place where they currently are (The Gerrer Rebbe, author of "Imrei Emet" in Piskei Teshuva Vol. 3, Ch. 252, holds that since one has already completely fulfilled their obligation, they are not obligated again—see there for his discussion regarding Yom Kippur and Passover. In contrast, Responsa "Betzel Hachochma" Vol. 4, Ch. 83 suggests that since one is now in a place where the sanctity of Shabbat exists, they are biblically obligated in this. See also Responsa "Torah Sheleima" Genesis note 430, and Responsa "Or Letzion" Ch. 14).
