abeles@mhuxm.UUCP (abeles) (02/09/85)
> > I never knew that time was variable, except maybe according to > Einstein. The fact that an Israeli keeps seven days is not a good analogy. > He does not keep it according to Israel time, but rather, local time. So > too in space. > > Eliyahu Teitz. If a person were to keep local time in space, a day (where the term day means the period of time from one sunrise or sunset to another) could be shorter than 3 minutes. This would arise because in a low orbit where the pull of gravity is strong a manned satellite would have to go at a speed of about 200 meters/sec to counteract the pull of gravity. (The acceleration of gravity is about 10 meters/sec/sec at the earth's surface. Centrifugal acceleration is the square of the velocity [200 * 200 = 40000 meters^2/sec^2] divided by the radius which is about the radius of the earth [4000 meters], or again about 10 meters/sec/sec. This 10 meters/sec/sec balances the pull of gravity and allows the orbit to exist.) If this spaceship goes at a speed of about 200 meters/sec, it would take only about 125 seconds (or under three minutes) to go around the world. This must be adjusted slightly to allow the orbit to take place above most of the atmosphere, but it will still be only a few minutes at such heights. The point is that in such a situation, Eliyahu Teitz would have an orthodox Jew daven shachris, mincha, and maariv in well under 5 minutes. What happens to kavannah (intention to pray; i.e., concentration) under these circumstances? Seriously, the result of this is that a Jewish human being would have to avoid such orbits since it would result in obligating him to pray continuously! No sleep! No eating! No going to the bathroom! Nothing but prayer! By taking off in a north-south orbit (which passes the north and south poles instead of circling the equator) such as is possible from Vandenburg Air Force Base in California (but not possible from Kennedy Space Flight Center in Florida), the observant Jew would be able to avoid these problems. So it would appear that we have discovered a new ramification of halacha! Or maybe halacha (only according to the Teitz point of view, of course) actually forbids space travel for Jews altogether! It already virtually restricts any travel to most places in the world--since kosher food isn't widely available in Borneo, Upper Volta, Czechoslovakia, Nigeria, Brazil, Japan, etc., etc., etc. So maybe it also restricts travel to any place outside the world. Eliyahu, we're waiting for your reply. A Good Shabbos to all, --J. Abeles
wkp@lanl.ARPA (02/10/85)
In article <310@mhuxm.UUCP> J. Abeles writes: > If a person were to keep local time in space, a day (where the term day > means the period of time from one sunrise or sunset to another) could > be shorter than 3 minutes. > > The point is that in such a situation, Eliyahu Teitz would have an orthodox > Jew daven shachris, mincha, and maariv in well under 5 minutes. What happens > to kavannah (intention to pray;i.e., concentration) under these circumstances? > > Or maybe halacha (only according to the Teitz point of view, of course) > actually forbids space travel for Jews altogether! There is an even more ludicrous scenario if the spaceship is moving with a velocity of 0.999993 the speed of light. In that case, in the reference frame of the spaceship, clocks in Israel are moving very fast: in fact, fast enough such that a day aboard the spaceship would see Israel celebrate an entire year of Jewish holidays. Since one is obligated to celebrate the Haggim according to the time in Israel, not only would our busy Yeshiva bocher astronaut be davening like mad because sunrise-to-sunset is only three minutes, but he would have to keep track of moosaf, ya'aleh v'yavoh, hallel, moreed ha'tal, etc., etc., on a daily basis! In other words, every day aboard the spaceship, our astronaut would be celebrating Rosh Hashanah and Yom Kipppur! What's worse is that every day he would have to search for Chametz, and change tableware, and throw all his bread out the vacuum chute! Imagine lighting eight different sets of Cahnukah candles in a time span of half-an-hour! Now imagine the even crazier situation in which the spaceship moves even faster! In this way, we would have solved the problem of conversion (at least in space) since no one would want to be Jewish anyway. --- bill peter {ihnp4,seismo}!cmcl2!lanl!wkp "Ben Azzai said, 'Do not be scornful of any person and do not be disdainful of anything, for there is no person without his hour and no thing without its place.'" ---
arnold@ucsfcgl.UUCP (Ken Arnold%CGL) (02/11/85)
In article <310@mhuxm.UUCP> abeles@mhuxm.UUCP (abeles) writes: >If a person were to keep local time in space, a day (where the term day >means the period of time from one sunrise or sunset to another) could >be shorter than 3 minutes. Previously, space flights operated on Houston time. I don't think this has changed on shuttle missions, but even if it has, it has changed to operate on someone else's 24 hour day (maybe the local time of the launch or landing site?). This makes issues of calendar easy to resolve. -- Ken Arnold ================================================================= Of COURSE we can implement your algorithm. We've got this Turing machine emulator...
teitz@aecom.UUCP (Eliyahu Teitz) (02/13/85)
long quote at end. As far as I can remember, I lit Channuka candles when the sun set in my home town of Elizabeth, N.J. and not when it set in Israel. Also, on Yom Kippur I ate until sunset at home and not in Israel and broke my fast the following night after nightfall here and not there. So why do you say that the holidays are dependent on Israel time? The holidays are dependent on local time. Therefore, when one goes where there is very little daylight on theoretically runs into a problem as to the time for prayer. There are many responsa on the issue, but the safest solution is to try and avoid those areas as much as possible ( if one really cares ). One final point on the issue. I detected a condescending tone in the article I am responding to. Not only are yeshiva students required to daven, but every Jew ( man and woman alike ) are obligated to pray in some manner daily. Of course, I might just have read too much into the article, but these sideswipes at the religious are really uncalled for. Eliyahu Teitz. > In article <310@mhuxm.UUCP> J. Abeles writes: > > > If a person were to keep local time in space, a day (where the term day > > means the period of time from one sunrise or sunset to another) could > > be shorter than 3 minutes. > > > > The point is that in such a situation, Eliyahu Teitz would have an orthodox > > Jew daven shachris, mincha, and maariv in well under 5 minutes. What happens > > to kavannah (intention to pray;i.e., concentration) under these circumstances? > > > > Or maybe halacha (only according to the Teitz point of view, of course) > > actually forbids space travel for Jews altogether! > > > There is an even more ludicrous scenario if the spaceship is moving with a > velocity of 0.999993 the speed of light. In that case, in the reference > frame of the spaceship, clocks in Israel are moving very fast: in fact, > fast enough such that a day aboard the spaceship would see Israel > celebrate an entire year of Jewish holidays. > > Since one is obligated to celebrate the Haggim according to the > time in Israel, not only would our busy Yeshiva bocher astronaut be > davening like mad because sunrise-to-sunset is only three minutes, > but he would have to keep track of moosaf, ya'aleh v'yavoh, hallel, > moreed ha'tal, etc., etc., on a daily basis! > > In other words, every day aboard the spaceship, our astronaut > would be celebrating Rosh Hashanah and Yom Kipppur! What's worse > is that every day he would have to search for Chametz, and change > tableware, and throw all his bread out the vacuum chute! Imagine > lighting eight different sets of Cahnukah candles in a time span > of half-an-hour! > > Now imagine the even crazier situation in which the spaceship moves even > faster! In this way, we would have solved the problem of conversion (at > least in space) since no one would want to be Jewish anyway. > > --- > > bill peter {ihnp4,seismo}!cmcl2!lanl!wkp > > "Ben Azzai said, 'Do not be scornful of any person and do not be > disdainful of anything, for there is no person without his hour > and no thing without its place.'" > --- *** REPLACE THIS LINE WITH YOUR MESSAGE ***