science

Shabbat siren

Shabbat siren is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Shabbat siren rather than just read about it. In short: In some Jewish communities, a Shabbat siren is sounded announcing the imminent onset of Shabbat and the required cessation of melacha at that time. Overview According to halakha, there are certain activities prohibited on Shabbat.

Key takeaways

Shabbat siren belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Shabbat siren to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Shabbat siren from memory before moving on to harder problems.

Reference excerpt

In some Jewish communities, a Shabbat siren is sounded announcing the imminent onset of Shabbat and the required cessation of melacha at that time.

Overview According to halakha, there are certain activities prohibited on Shabbat. Some Jewish communities sound a converted civil defense siren on Friday afternoon to announce that Shabbat will begin in order to warn and remind the local Jewish residents to stop doing such activities. In Jerusalem, the siren goes off 40 minutes before Shabbat. In other areas, including Brooklyn, the siren is sounded twice, once 15 minutes before Shabbat and a second time immediately before the start of shabbos.

History The Talmud (Shabbat 35b) relates that on the eve of Shabbat, six shofar blasts (two series of Teki’a-Teru’a-Teki’a blows) were sounded to announce that Shabbat was approaching. Each blast represented a different act done to prepare for shabbos. The first blast told the workers in the fields to cease working and to return to the city. The second blast told shops and inns in the city to close their stores. The third shofar blow told the people of the city that it was time to light the shabbos candles. The last shofar blows told the people that it was the instant before shabbos. After the onset of shabbos the blower ceased blowing and released the shofar because it was forbidden to blow shofar on shabbos or even hold the shofar (mukzah). Rabbi Yaakov Chaim Sofer writes that this custom should be continued in a place where the Jewish populace is in control and unafraid of gentile repercussions. If an actual shofar cannot be used, a siren or bell can be used in its place. Excavations of the kotel wall after the Six-Day War revealed a stone platform on the top of the southwest corner of the outer section of the wall. This platform was the place where the shofar blower would stand in temple times as shown from an inscription on the rock that says "the place of the trumpeter".

Criticism

Many residents of Brooklyn neighborhoods that have such a siren have complained that the noise produced by the siren is too loud. One siren atop a synagogue in Bedford–Stuyvesant, Brooklyn has been said to reach 106 decibels. In response to complaints from local residents, the New York City Department of Environmental Protection issued five noise code violation summonses to Yeshiva Toras Emes, a yeshiva located in Brooklyn that has such a siren. The Jewish residents protest this opposition, countering with the seeming acceptance of mosque's call to prayers which take place at sunrise, and which reach similar levels of noise.

Worked examples

Example 1 — a first encounter with Shabbat siren

Start with the simplest possible case. Write down what Shabbat siren claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Shabbat siren before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Shabbat siren ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Shabbat siren

In research: Shabbat siren appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Shabbat siren in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Shabbat siren is common in secondary-school and first-year university syllabi. It links to neighbouring topics Jews and Judaism in Brooklyn, Jews and Judaism in Jerusalem, Judaism-related controversies, so understanding it makes those chapters shorter.
In everyday life: Look for Shabbat siren outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Shabbat siren in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Shabbat siren means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Shabbat siren out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Shabbat siren in simple terms?

In some Jewish communities, a Shabbat siren is sounded announcing the imminent onset of Shabbat and the required cessation of melacha at that time. Overview According to halakha, there are certain activities prohibited on Shabbat.

Why does Shabbat siren matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Shabbat siren?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Shabbat siren.