The atmosphere, a thin veil of molecules enveloping Earth, reaches about 20 miles (32 kilometers) above the planet's surface.

That bleak future may never arrive, however, if the expansion slows. In fact, in one scenario, the universe could even re-collapse. There’s a name for that: the “Big Crunch.” Astronomers ...

The expansion of the universe is, in some ways, similar. But this analogy gets one thing wrong – while the dough expands into the baking pan, the universe doesn’t have anything to expand into.

What is the universe expanding into if it’s already infinite? – Mael, age 10, Missoula, Montana When you bake a loaf of bread or a batch of muffins, you put the dough into a pan. As the dough bakes in ...