number - Tzitzit tying: the real way

1)There are two authentic ways to tie the Sisit (Tzitzis) that have sources. Maran writes to make 7-9-11-13. First question: why does he write this is he then says Gimtarya Hashem is One, when in fact it is not- Hashem is One in Hebrew is 39 and Maran wrote 40 which is not Hashem is One?

2) Why don't at least the Ashkenazim follow the Mehaber's minhag of 7-9-11-13?

3) There is a custom that stems back from Rav Shelomo Molecho who used to make Sisit 10-5-6-5 by individual wraps and the Hida brings that down as Halacha (and see Yalkut Yosef, Sheerit Yosef vol. 1, siman 11) to make it 10-5-6-5. However, for some reason some people took that way and mixed it with the way of the Arizal (see Shaar HaKawanot vol. 1, Tzitzit Derush 6 if I remember correctly) to make 3 Huliot and make 7-8-11-13, as brought down by Kaf HaHaim (siman 11) and the Shulhan Aruch HaRav (see Halacha Berura 11). My question is, some people took the way of the Ari and mixed it with the way of Hida. The Ari clearly states to make 7-8-11-13 with Huliot of 3, and when the Hachamim were talking about the Hida's method it means one by one in the 10-5-6-5 method. However, the popular Sephardic custom to me seems to be made up, and not have any source. Can someone give a source for this method of the 7-8-11-13 with the knots through them without the Huliot of 3?

Answer

This seems like multiple questions and I will suffice with addressing the first two:

1) The mechaber clearly states (OC 11:14) that 40 wraps is for 39+1, 39 being the gematria of Hashem Echad and 1 for the name itself. This (adding 1 for the entire object) is not at all an uncommon technique to use in gematria.

2) Since when have Ashkenazim been bound by the Mechaber's minhagim? The Mishna Berurah (sk 70) says that the "Achronim" argue on the Mechaber and rule 7-8-11-13 and that is what most Ashkenazim do.

everyday chemistry - Sugar solutions have a neutral pH in themselves, but it makes your body acidic. Why?

I'm not an expert, but as far as I understood a sugar solution is completely neutral since sugar can't take hydrogen ions out of the water or donate them in. Sugar is a non ionic compound, so it does not release H and OH ions in the water so it will not make the solution acidic or alkaline.

I keep on reading and seeing charts of how sugars make your body acidic, like this one:

What process makes a neutral pH solution into an acidic one? I'm not into chemistry at all and therefore the simpler the answer the better.

Answer

It is not proven that "sugar makes your body acidic"!

Your body's pH is very tightly regulated by the body's internal systems; it is also different in different parts of the body - the stomach is acidic (1.0-2.5), the intestine are mildly basic (jejunem 7-9) terminal ileum 7.5 reference here. Blood pH is 7.35, and any deviation from this is indicative of serious illness.

physical chemistry - Why does Le Chatelier's principle not apply to pure solids and liquids?

If we had a homogeneous reaction of pure liquids only, would Le Chatelier's principle still apply ?

Also, wouldn't increasing the amount of solid in a heterogeneous reaction mixture at equillibrium result in more product, therefore indicating a shift in equilibrium?

tetzaveh - Moshe's name is missing

Why is Moshe name not mentioned in parshas Tetzaveh?

Answer

Me'or Einayim points out that Tetzaveh is (nearly) always read immediately before or after the seventh of Adar, which is Moshe's (birthday and) yahrtzeit. So his name is missing from this parshah specifically, in mourning for our loss.

On a more positive note, there is a long talk by the Lubavitcher Rebbe zt"l (Likkutei Sichos, vol. 21, pp. 173ff; adapted into English at Chabad.org) in which he points out that in a sense Moshe is present even more in this parshah than usual. Its very first word, ואתה, "and you," expresses his existence even more strongly than the use of his name.

He then goes on to explain what Moshe was trying to accomplish with his "threat." He was demanding that G-d be willing to re-establish His relationship with the Jewish People on an essential level that transcends Torah, and that if He wouldn't be willing to do so, then Moshe was prepared to forfeit his place in the Torah in favor of retaining his connection with his people. Thus,

Tetzaveh stands as an eternal tribute to Moses. It is the Torah’s own testimony to Moses’ greatness in relinquishing everything—including his bond with Torah—in order to preserve his bond with his people and restore them to their G-d.

Is the equilibrium constant calculation only applicable to homogeneous reactions?

In my text book, it states the general formula for the equilibrium constant is:

Then it states that "The equilibrium constant expressions described here apply to homogeneous reactions."

Does this mean that it only applies to homogeneous reactions or that it can also be applied to homogeneous reactions among other types?

Answer

If you introduce the chemical activity $a$ in thermodynamics you can write the general equation.

$$ \frac{a_C a_D}{ a_A a_B} = K$$

which is correct for any case. Under ideal assumptions we have a linear relationship between the activity and concentration in solution. So with an arbitrary normalizing reference concentration $c_0$ (e.g. 1 mol/l) the equation becomes roughly:

$$ \frac{c_C / c_0 c_D / c_0}{ c_A / c_0 c_B / c_0} = K$$

As you see the $c_0$ cancel each other out and you end up with the textbook equation that consists only of concentrations.

So the equation applies if you can scale your activities linearly with concentrations. This is usually possible for homogeneous reactions and sometimes possible for heterogenous reactions (As can be seen from the other answer).

PS: Activities hence equilibrium constants are dimensionless. You always have a factor 1 (mol/l)$^n$ to cancel out the units of the concentrations, if you derive it correctly.

conversion to judaism - How should a modern non-Jew interpret commandments in the Torah that they perceive to command individual violence?

If a non-Jew is interested in Judaism, how should they approach commands in the Torah like Exodus 21:17, Exodus 31:14, Leviticus 20:13? Should these passages be seen not just as command not to do the prohibited things but also a command to carry out the punishment of death? After all, these commands are not "do not do this" but "if a person does this, he must be put to death." How can a non-Jew who is considering conversion justify committing themselves to a law that they consider themselves breaking if they don't, for example, stone an adulterer and adulteress?

sources mekorot - Origin of the Escalator analogy

What is the origin of the escalator analogy of always striving for growth? I'm referring to the analogy that, in life, like a person climbing a downward escalator, if one is not constantly striving higher and moving forward, one is by definition moving backward and downward, not merely at rest.

I've heard this as inspiration and Divrei Hizzuk inserted into Divrei Torah, but there is obviously no Midrash that would have used this exact analogy. I assume that, if it has Jewish origins, it would have to be a 20th Century rabbi or Jewish theologian (the first working escalator was installed in 1896 - Wikipedia). Who coined it, and when?