To figure out how much we should spend fighting climate change, economists have some questions for you: How much would you be willing to spend now to make your child $100 richer in the future? What about your grandchild in the farther future, or your great-great-great-great-great-grandchild in the very distant future? The health of the planet may hinge on the answers. Most economic analyses of climate change have concluded that we should be spending only small amounts to combat climate change now, ramping up slowly over time. This conclusion mystifies most climate scientists, who argue that i...

The reclusive mathematician who proved the Poincaré conjecture may or may not claim his prize.

Mathematicians find new answers to the still puzzling theorem that four colors suffice to color any map.