Quantcast
issue
Read articles, including Science News stories written for ages 9-14, on the SNK website.
A different kind of knot

Objects are considered topologically identical if they can be transformed from one into another without cutting or pasting; the classic example is a doughnut and a coffee mug. In contrast, a loop and a trefoil knot (right) are topologically distinct. Credit: Diane39/Istockphoto

Follow Us
blogs & columns
multimedia
Not to miss
bookshelf