[Avodah] size of a kezayit

[Zev Sero]

Eli Turkel wrote:
> The kaf hachaim says to use weight and not volume.
> 
> See
> http://www.vbm-torah.org/pesach/pes62-yr.htm 
> for all the glory details of how much to eat and all the shitot


There is no opinion, anywhere, that shiurim are determined by weight.
The web page cited creates a machlokes out of thin air.  The most practical
way to determine the volume of a solid is to weigh it and multiply by its
known density.  That's all.

Now we do seem to have a dispute about the density of matzah, since
all the older sources assume it to have approximately the same density
as water, and the well-attested minhag in EY was to weigh 9 dirhams of
matzah for a kezayit, explicitly on this assumption that it has the
same density as water.  If more recent experimental data shows this
assumption to have been incorrect, then the weight required must be
adjusted accordingly.

One issue may be how to determine the density; how big a hole can be
ignored?  We know that "sponge bread" is measured as it is, but what
exactly does that mean?  AFAIK the accepted explanation is that only
microscopic holes can be ignored, but any hole that can be seen must
be deducted from the volume.  The only practical way to do this is
to squash the bread before measuring its volume.

-- 
Zev Sero               Something has gone seriously awry with this Court's
zev at sero.name          interpretation of the Constitution.
                       	                          - Clarence Thomas