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Don't tamper with SI-unit consistency

Nature volume 549, page 160 (2017) Cite this article

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I disagree with your suggestion to promote the radian to the International System of Units (SI units) to address the confusion over dimensionless numbers (Nature 548, 135; 2017). On the contrary, this could perpetrate the mistaken view that everything in the physical world has dimensions.

The humble planar angle is an example. As the ratio of the length of a swept arc to the radius of that arc, it is dimensionless. Typically, however, people append the radian label directly to the resulting number, or attach other tags — such as degrees, gradians or minutes of arc — having used other conversion factors.

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  1. Washington University, St Louis, Missouri, USA

    Michael C. Wendl

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  1. Michael C. Wendl
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Correspondence to Michael C. Wendl.

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Wendl, M. Don't tamper with SI-unit consistency. Nature 549, 160 (2017). https://doi.org/10.1038/549160d

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