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Questions tagged [notation]

This tag is for questions on the meaning, history, and usage of various symbols and notation that are used to denote different quantities in physics. Don't forget to mention the reference, where you encountered those notations.

In Physics, various symbols or notations are used to denote different quantities. The denotations make the representation of the quantities easier. It is interesting to note that some physics symbols are very relatable (like “d” for distance) while some are unrelatable (like “c” for the speed of light). To get better response, please remember to mention where (book, paper, webpage, etc.) from where you encountered those.

For some known notations see The Physics Hypertextbook; List of common physics notations; etc.

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Should zero be followed by units?

Today at a teachers' seminar, one of the teachers asked for fun whether zero should be followed by units (e.g. 0 metres/second or 0 metre or 0 moles). This question became a hot topic, and some teachers were saying that, yes, it should be while…
Vidyanshu Mishra
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Difference between $\Delta$, $d$ and $\delta$

I have read the thread regarding 'the difference between the operators $\delta$ and $d$', but it does not answer my question. I am confused about the notation for change in Physics. In Mathematics, $\delta$ and $\Delta$ essentially refer to the same…
Yuruk
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Mathematically-oriented Treatment of General Relativity

Can someone suggest a textbook that treats general relativity from a rigorous mathematical perspective? Ideally, such a book would Prove all theorems used. Use modern "mathematical notation" as opposed to "physics notation", especially with respect…
3Sphere
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Is it foolish to distinguish between covariant and contravariant vectors?

A vector space is a set whose elements satisfy certain axioms. Now there are physical entities that satisfy these properties, which may not be arrows. A co-ordinate transformation is linear map from a vector to itself with a change of basis. Now the…
Isomorphic
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Why ket and bra notation?

So, I've been trying to teach myself about quantum computing, and I found a great YouTube series called Quantum Computing for the Determined. However. Why do we use ket/bra notation? Normal vector notation is much clearer (okay, clearer because I've…
auden
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Partial derivative notation in thermodynamics

Most thermodynamics textbooks introduce a notation for partial derivatives that seems redundant to students who have already studied multivariable calculus. Moreover, the authors do not dwell on the explanation of the notation, which leads to a poor…
1__
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Square bracket notation for dimensions and units: usage and conventions

One of the most useful tools in dimensional analysis is the use of square brackets around some physical quantity $q$ to denote its dimension as $$[q].$$ However, the precise meaning of this symbol varies from source to source; there are a few…
Emilio Pisanty
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What does an integral symbol with a circle mean?

I have frequently seen this symbol used in advanced books in physics: $$\oint$$ What does the circle over the integral symbol mean? What kind of integral does it denote?
user11543
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8 answers

Is there a symbol for "unitless"?

I'm making a table where columns are labelled with the property and the units it's measured in: Length (m) |||| Force (N) |||| Safety Factor (unitless) ||| etc... I'd like not to write "unitless" on several columns...and I'm quite surprised I…
Ben
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Can units be plural?

I was in a conversation with my senior engineer where he kept on insisting that we can use plural when we write down any unit. I argued that it is not the 'common' practice or even throughout my whole academic career (unfortunately) I haven't found…
Ahmed
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Symbols of derivatives

What is the exact use of the symbols $\partial$, $\delta$ and $\mathrm{d}$ in derivatives in physics? How are they different and when are they used? It would be nice to get that settled once and for all. $$\frac{\partial y}{\partial x}, \frac{\delta…
Steeven
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What does the notation $8.9875517923(14)$ mean?

The number $8.9875517923(14)$ appears in Coulomb's constant. I have read that it has something to do with the uncertainty of the accuracy of the number but answers have been unclear. Can somebody define the meaning of such notation?
James Adrian
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How to "decipher" the symbol for the recently announced doubly-charmed baryon?

The name of the particle (resonance?) in the recent announcement Observation of the doubly charmed baryon $\Xi^{++}_{cc}$ is complicated. I'm sure it's standard notation but I don't know how to "decode" it. Is it possible to explain the Xi and the…
uhoh
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Derivative with respect to a vector is a gradient?

I've encountered in some books (and even completed an exercise from the Goldstein by using it), a strange notation that seems to work exactly like a gradient, I have tried to look for an explanation but found none yet and I think I can reduce the…
Mark A. Ruiz
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Why is the candela a base unit of the SI?

The candela is defined as The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency $540\cdot10^{12}$ hertz and that has a radiant intensity in that direction of $1/683$ watt per…
Gerard
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