Volume 11 Number 66
                       Produced: Sun Feb  6 20:59:47 1994

Subjects Discussed In This Issue: 

Genesis and the Big Bang (2)
         [Steve Wildstrom, Robert Israel]
Jospehus (and Mormon Software)
         [Zvi Basser]
         [Aryeh Blaut]
Misrepresentation of Halakha as Safeguard
         [Aryeh Frimer]
SHabbat for One or Both?
         [Gedalyah Berger]
Talking during davening
         [Alan Mizrahi]
         [Isaac Balbin]
Yarmulke: minimal acerage
         [Mechy Frankel]
YU seforim sale
         [Ari Z. Zivotofsky]


From: Steve Wildstrom <wild@...>
Date: Thu, 3 Feb 94 23:01:07 -0500
Subject: re: Genesis and the Big Bang

In MJ 11/56, Robert J. Tasnnenbaum asks how to calculate a situation in 
which one observer would see the passage of 15 billion years while 
another saw just six days.

I'm hardly a physiscist, but I think I know enough to answer this. The 
special theory of relativity holds that time a stationary observer sees 
time pass more quickly than a moving observer within the same frame of 
reference. Specifically, time is dilated, or slowed down, by a factor of
where v is the velocity of the moving observer and c is the speed of 
light, 300,000,000 meters per second. If v is very small relative to c, 
as it is for all normal human activities, the term v^2/c^2 is very close 
to zero and can be ignored.
  But to get from six days to 15 billion years requires a time-dilation 
factor on the order of 10^12. Working through the algebra, this requires 
a velocity considerably in excess of 99.9% of the speed of light.

Without beginning to grapple with any theological implications, what 
this means is that if the two observer were next to each other 15 billion 
years ago, they would now be something like something like 10^23 
kilometers (that's 1 followed by 23 zeros) apart.

Steve Wildstrom   Business Week Washington Bureau  <wild@...> 

From: Robert Israel <israel@...>
Date: Thu, 3 Feb 94 23:26:52 -0500
Subject: Re: Genesis and the Big Bang

In vol. 11 #57, Ezra Bob Tanenbaum asks about Gerald Schroeder's book 

"Genesis and the Big Bang":

> My question: Does anyone out there know of any theoretical reference
> point from which we could calculate a difference in the experience of
> time which would make 6 days equivalent to 15 billion years of time
> as we experience it? He doesn't provide such calculations - and I believe
> it would make his thesis more believable if he did.

At last a question I know a bit about!  Unfortunately, I think doing
the calculations makes it less believable rather than more.

There are two ways to make time "slow down" in relativity: 

(1) move at a speed close to the speed of light, or
(2) be in a place where the gravitational potential is low.

To make 15 billion years into 6 days requires slowing down by a factor
of about 10^12.  In method (1), if your speed is v (in units where the
speed of light is 1), the factor is (1 - v^2)^(-1/2), so v would have to
be approximately 1 - 5 * 10^(-25), i.e. 99.99999999999999999999995
percent of the speed of light.  This is so fantastically close to the
speed of light that if an object travelling at that speed in a straight
line emitted a light signal 15 billion years ago, the light signal would
arrive only about 0.2 microseconds (about one clock cycle on an old IBM
PC) before the object did.

Actually, there are complications here: the "frame of reference" can't
be an inertial frame (moving at constant speed in a straight line in a
flat space-time) because an observer moving in an inertial frame would
also consider _us_ as slowed down.  From the point of view of such a
moving observer, the creation would have taken place at different times
in different places, and from the start of _our_ creation (i.e. creation
at the place where the matter that was to become Earth) to the end (at
the Earth) would actually have taken much _longer_ than 15 billion
years.  On the other hand, an observer moving in a curved path, starting
and ending at the appropriate events on Earth, could measure a duration
of 6 days between those events.

In method (2), if you are stationary at a distance r from the centre of
a spherically symmetric gravitating body with mass M (in appropriate
units), time is slowed down by a factor (1 - 2M/r)^(-1/2).  Therefore we
need r to be approximately (1 + 10^(-24)) 2M.  Well, the "body" will
have to be a black hole, and 2M is the location of the event horizon:
anything inside the event horizon can never escape or send a signal to
the outside.  For a black hole of the mass of the sun, M is about 1500
metres, so r - 2M would be about 3 * 10^(-21) metres.  It's difficult to
convey how fantastically small this distance is: about a millionth of
the radius of an electron.

I venture no opinions on why the Torah would be written from the point of 
view of an observer moving in circles at 99.99999999999999999999995 percent 
of the speed of light, or hovering extremely close to the event horizon of
a black hole.

Robert Israel                            <israel@...>
Department of Mathematics             
University of British Columbia
Vancouver, BC, Canada V6T 1Y4


From: <fishbane@...> (Zvi Basser)
Date: Sun, 6 Feb 94 19:07:49 -0500
Subject: Re: Jospehus (and Mormon Software)

re Jospehus:
I have never heard of any rishon who knew Josephus. They refer to
Sefer Yossipon. That's another story. AS for mormon software, as far
as I know it is permissable to buy milk from dairies run by monasteries.
it may be that on their holy days we do not do this.

zvi basser


From: Aryeh Blaut <ny000592@...>
Date: Fri, 4 Feb 94 12:05:23 -0500
Subject: Re:  Kippot

>From: Zev Farkas <farkas@...>
>is there any halachic basis for a yarmulka having to be of a certain size,
>color, shape, thickness, texture, opacity, or number of layers?

I have not looked into this topic for many years now, but in looking 
over my notes from a class:

1)  Kidushin 31a: "...not to walk 4 amos (about 8 feet) w/out head covering.

2)  Shabbos 118 & 156 makes a statement about head covering & reward for
	 doing so.

3)  Rav Avadya Yosef: Today, not to have on a kippa is a maris eyen (bad look)
	that one doesn't accept the "Heavenly Kingdom".

4) Beis Yosef --> Kol Bo: Having one is only a Midas Hasidus (religious

5)  Maharshal & the Gra say that it is a minhag k'halacha (custom like law).

6)  Type & Size: There is no meaning to the type of kippa.  Rav Moshe 
ZT"L brings down R' Shlomo Kluger -- full head cover (based on Rov (most)).
Rav Moshe disagrees & my Rosh Kollel taught as follows:  If strict, 
follow R' Kluger (no obligation because he's only 1 opinion).  R' Avadya 
Yosef rejects R' Kluger.  He says that it is okay for small, but it 
needs to be seen from the sides.  He says that it only needs to be large 
for blessing after meals, prayer.

Aryeh Blaut


From: Aryeh Frimer <F66235@...>
Date: Sun, 6 Feb 94 03:53:58 -0500
Subject: Misrepresentation of Halakha as Safeguard

    As some of you know, I am "still" working on an article regarding
Women's services and have come across an intersting question in which I
would like some input and thought. Nagid (let's say) that a Rabbi or
group of Rabbis is convinced that a particular innovative practice (for
argument's sake Women's Services) is per se' Halakhically permitted.
However, they are equally convinced that it is fraught with danger for
Klal Yisrael; i.e., it's bad public policy for whatever reason. Are they
allowed to rule that it is "Halakhically" forbidden - perhaps even give
very weak halakhic arguments to sort of "cover up" -  for the sole
reason that by doing so their prohibition will carry greater weight?
Clearly a Rabbi has the right to prohibit something for his community on
the grounds that he thinks it is "bad for the Jews" - and his community/
congregants who have accepted him as their halakhic authority are
obligated to follow him. But here we are talking about misrepresenting
Halakha by forbidding the permitted - for the purpose of Migdar Milta
(prevention of future halakhic problems).  Do the ends justify the
means.    Sources appreciated.


From: Gedalyah Berger <gberger@...>
Date: Thu, 3 Feb 94 23:00:33 -0500
Subject: SHabbat for One or Both?

In #55, Joel Goldberg wrote about "Chol Jews" doing melachah (work 
forbidden on Shabbat) for "Shabbat Jews":

> Jan David Meisler <jm8o+@andrew.cmu.edu>
>  Asked about:
> > what about if a person followed Rabbeinu Tam's opinion on when Shabbos
> > ended, and the rest of the community followed by the Gra (which is
> > earlier), could the person who followed by Rabbeinu Tam time travel in
> > a car while he still held it was Shabbos, but the other person did not?
> This situation came up for my wife once, in her childhood in Kew Gardens
> Hills. She is confined to a wheelchair, and as usual had gone to the early
> (in summer) erev shabbat minyan with her father. At davening, it was announced
> that the eruv was down. Pushing a wheelchair is the same as pushing a baby
> carriage, so there was a problem. The rav paskened that a person who had not
> yet accepted shabbat could drive her home. Of course, the circumstances
> are not the usual ones.

The case here is not comparable to that which Jane asked about.  Here, 
both people involved (i.e., the person who needs the melachah done and 
the person who does it) agree that for one of them it is Shabbat already 
and for one of them it isn't; one of them was mekabel Shabbat early, and 
the other was not.  The question was about a case of differing 
piskei halachah, not differing circumstance; in that case, the one who 
paskens like the Gr"a really believes that it is already Shabbat 
mide'oraita and that no Jew, including one who may pasken like Rabbeinu 
Tam, may now do melachah. In other words, according to his understanding 
of the halachah, the other person is simply wrong that it is not yet 
Shabbat.  In that case, I would be very surprised if any posek would 
permit asking the other person to do melachah for you.

Gedalyah Berger
Yeshiva College / RIETS


From: <amizrahi@...> (Alan Mizrahi)
Date: Sun, 06 Feb 94 19:01:20 EST
Subject: Talking during davening

I have always been curious about something:  in almost all siddurim, it
states at various points that one is not allowed to talk at certain times.
Usually it is from the beginning of p'sukei d'zimrah until after chazarat 
haShatz, (or from Borchu at Ma'ariv).  Does this imply that one is allowed
to talk during other parts of davening?

-Alan Mizrahi


From: Isaac Balbin <isaac@...>
Date: Fri, 4 Feb 94 11:30:47 -0500
Subject: Re: Yarmulka

  | From: <barbery@...> (Yacov Barber)

  | coresponding to two levels of intellect. R' Yohoshua of Belz once said that
  | Yarmulka has the same letters of Yira Elokim, and the 2 coverings
  | correspond to the 2 levels of fear of Hashem. The Lubavitcher Rebbe Shlita
  | {may he have a speedily and complete recovery} writes in Igrois Kodesh
  | {vol. 10 p. 394} that one can bring a source to the custom of wearing 2
  | head coverings {Chulin 138.} from the fact that the Cohen Gadol would wear
  | a woollen Yarmulka under the Priestly hat.

Well, this article arrived here on Erev Shabbos, 23 Shvat. That happens to be
the Yortzeit of R' Yehoshua of Belz. I am not a Belzer [I just happen
to daven in a minyan that won't say Tachnun when a Chassidic master
passed away] An interesting bit of trivia.

Anyway, does a yarmulka with lining count for two head coverings?


From: Mechy Frankel <frankel@...>
Date: Fri, 4 Feb 1994 12:56:32 EST
Subject: Yarmulke: minimal acerage

In response to the inquiry by Z. Farkas re halachic requirements for yarmulke
geometry and material properties,  I am reminded of a response I heard many
years ago in yeshiva (attributed by the teller to R. J. Weiss) ." It only has
to be big enough to cover your brain."

Mechy Frankel


From: <azz@...> (Ari Z. Zivotofsky)
Date: Fri, 4 Feb 94 12:33:32 -0500
Subject: YU seforim sale

	I believe that the annual YU seforim sale is set to start next
week and I was wondering if anyone knows if the book list (which I'm
sure is prepared on computer) is available by FTP, and if not if someone
at YU can suggestion that they make it available. It would be especially
helpful for those of us who do not live in the NY area.


End of Volume 11 Issue 66