Along the way, however, they were fooled again and again. Sometimes two knots looked different, but were really the same. Other times, something that looked like a knot was really an unknot. To keep from getting fooled, mathematicians looked for formulas that would serve as shortcuts for telling a knot from an unknot and one knot from another. They're still looking for a single formular that covers all possible knots.
Most mathematicians study knots just because they enjoy it.
But figuring out knots can help others understand more about how the world works. Biologists, for example, study knots so tiny you need an electron microscope to see them. Heaps of DNA strands sit like microscopic spaghetti inside plant and animal cells. DNA carries the code that tells each cell what to do. When scientists started to sort out the DNA strands found in cells, they discovered some unexpected loops and knots.