science

Siebs's law

Siebs's law 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 Siebs's law rather than just read about it. In short: Siebs's law ( ZEEPS) is a Proto-Indo-European (PIE) phonological rule named after the German linguist Theodor Siebs. According to this law, if an s-mobile is added to a root that starts with a voiced or aspirated stop, that stop is allophonically devoiced.

Key takeaways

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

Reference excerpt

Siebs's law ( ZEEPS) is a Proto-Indo-European (PIE) phonological rule named after the German linguist Theodor Siebs. According to this law, if an s-mobile is added to a root that starts with a voiced or aspirated stop, that stop is allophonically devoiced. Compare:

PIE *bʰr̥Hg- > Latin fragor, but *s-bʰr̥Hg- > PIE *spʰr̥Hg- > Sanskrit sphūrjati.

Discussion Siebs proposed this law in the Zeitschrift für vergleichende Sprachforschung auf dem Gebiete der indogermanischen Sprachen ('Journal for Comparative Linguistic Research in the Field of Indo-European Languages'), as Anlautstudien ('Initial Sound Studies'). Oswald Szemerényi rejected this rule, explaining that it is untenable and cites the contradiction present in Avestan zdī from PIE *s-dʰi "be!" as counterproof. However, the PIE form is more accurately reconstructed as *h₁s-dʰí from *h₁es- (so not an s-mobile) and thus Siebs' law appears to demand that the sibilant and aspirated stop are both adjacent and tautosyllabic, something which is known to only occur in word-initial position in Proto-Indo-European anyway.

See also Glossary of sound laws in the Indo-European languages

References

Sources Collinge, N. E. (1985). The Laws of Indo-European. John Benjamins Publishing Co. ISBN 978-0-915027-75-0. Szemerényi, Oswald (1999). Introduction to Indo-European Linguistics. Oxford University Press. ISBN 978-0-19-823870-6. Siebs, Theodore (1904). Zeitschrift für vergleichende Sprachforschung auf dem Gebiete der indogermanischen Sprachen.

Worked examples

Example 1 — a first encounter with Siebs's law

Start with the simplest possible case. Write down what Siebs's law 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 Siebs's law 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 Siebs's law 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 Siebs's law

In research: Siebs's law 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 Siebs's law 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: Siebs's law is common in secondary-school and first-year university syllabi. It links to neighbouring topics Indo-European language stubs, Indo-European sound laws, Phonology stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Siebs's law 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 Siebs's law in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Siebs's law 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 Siebs's law out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Siebs's law in simple terms?

Why does Siebs's law 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 Siebs's law?

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 Siebs's law.