When you take a look at the Universe in great detail, a few facts jump out at you that might be surprising. All the stars, galaxies, gas, and plasma out there are made of matter and not antimatter, even though the laws of nature appear symmetric between the two. In order to form the structures we see on the largest scales, we require a huge amount of dark matter: about five times as much as all the normal matter we possess. And to explain how the expansion rate has changed over time, we need a mysterious form of energy inherent to space itself that's twice as important (as far as energy is concerned) as all the other forms combined: dark energy. These three puzzles may be the greatest cosmological problems for the 21st century, and yet the one particle that goes beyond the standard model — the neutrino — just might explain them all.

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