Âé¶¹´«Ã½

This week’s new questions

Why can squirrels run straight down a tree, and could my cat do the same thing if it had to? Also, why are at least four faces required to make a flat-faced solid in 3D?

16 July 2025

MKC0KM white cat climbing on a tree

Sylvia Born/Alamy

Last Word is Âé¶¹´«Ã½â€™s long-running series in which readers give scientific answers to each other’s questions, ranging from the minutiae of everyday life to absurd astronomical hypotheticals. To answer a question or ask a new one, email lastword@newscientist.com

Why can squirrels run straight down trees? And could my cat do the same thing if it had to?

Robert Morley

London, UK

Origami tetrahedrons background. Futuristic polygonal composition with copy space on the left side.; Shutterstock ID 384802414; purchase_order: -; job: -; client: -; other: -

Ju.Hrozian/Shutterstock

Why are at least four faces required to make a flat-surfaced solid in 3D? And does a similar lower limit apply in higher dimensions?

John Corey

Melrose, New York, US

To answer this question – or ask a new one – email lastword@newscientist.com.

Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.

Âé¶¹´«Ã½ retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.

Terms and conditions apply.

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox. We'll also keep you up to date with Âé¶¹´«Ã½ events and special offers.

Sign up
Piano Exit Overlay Banner Mobile Piano Exit Overlay Banner Desktop