Tuesday, October 2, 2018

halacha - Rockets from Gaza while praying


I live in Beer Sheva, Israel where there are presently ongoing rockets fired at us from Gaza. We are warned of an impending rocket by a loud siren that gives us less than a minute to run to a bomb shelter. Now that's it time for the Maariv, I'm feeling quite apprehensive about approaching prayer in general and realized a few questions.


I am not seeking practical halachic advice for which I can ask my Rav. I'm interested to know the sources on the basis of which my Rav would decide.



  • If I'm in the middle of the Amida and a siren goes off I will of course run to a shelter to save my life. Until I can return to my home and continue praying again (maybe 10 minutes later), is it forbidden for me to speak?

  • Would I have to start over again from the beginning of the Amidah?


  • If a person is stricken with fear of an impending siren, are they released from the obligation to pray? As this situation might last for several days, I don't think one could hope for a tashlumin.


Obviously, I never before considered the context of such halakhot, but they are quite pressing and real. I would be grateful if someone could help me out, as well as ask everyone here to have us in your tefillot.



Answer



Point 1:


See Mishnah Brurah 104:25 that says it is forbidden to speak unless one is an Oines.


Point 2:


See Mechabar 104:5 that says if the hefsek took as long as it takes to finish the Tefilla then one must start over, otherwise one starts again from the Bracha that he was in the middle of. For more complicated details look at the Mishnah Brurah there.


Point 3:


The Mechaber in simon 98:2 says ideally one should not pray in a time when one has not got presence of mind (see Mishnah Brurah for a examples of pain, anger [and I suppose one could add fear as well]) however nowadays since we anyway do not have that much concentration we should daven even in such a time. See the Mishnah Brurah there that says one should still try and put ones thoughts out of the mind first.



Anomalous electronic configuration of platinum


Why is the electronic configuration of platinum $$\mathrm{[Xe] 4f^{14} 5d^9 6s^1}$$


and not $\mathrm{[Xe] 4f^{14} 5d^{10} 6s^0}$ or $\mathrm{[Xe] 4f^{14} 5d^8 6s^2}$?




Monday, October 1, 2018

history - How does orthodox Judaism view the Dead Sea Scrolls?


I'm trying to understand how orthodox Jews view the dead sea scrolls. Are they considered authentic representations of Judaism? If there are textual variants between our current tanach texts and the scrolls are the scrolls seen as more accurate? Do any contemporary poskim discuss the place of the scrolls, how they should be viewed etc?




grammar - Are な and だ both copula verbs?


What is the grammatical relationship between these two words?


Are they just different words expressing the same concept, is one the derivation of the other or is a third option true?




orbitals - Why do no known atoms have electrons in the g or h subshells?


I'm learning about orbital quantum numbers. While checking several elements on the periodic table I noticed that there aren't any atoms that have electrons in the g or h subshells. Why is this?




organic chemistry - Why is Diels–Alder adduct exo when we leave it for a while?


Recently we did an experiment of Diels–Alder reaction and we left the adduct overnight. I've read a paper of Woodward that says the adduct of Diels–Alder thought to be endo, whereas in our experiment it turned out to be exo.




words - Genesis 2:7 vs 2:19


Genesis 2:7 And the Lord G-d formed man of the dust of the ground vs. :19 And out of the ground the Lord G-d formed every beast of the field


I just want to know the difference between "the dust of the ground" and "the ground" in Hebrew, and if is two different words that are used and what they are.




periodic trends - Comparing radii in lithium, beryllium, magnesium, aluminium and sodium ions

Apparently the of last four, $\ce{Mg^2+}$ is closest in radius to $\ce{Li+}$. Is this true, and if so, why would a whole larger shell ($\ce{...