Alessandro Melchiorri

The Universe has been singing its majestic symphony of expansion for almost 14 billion years. Astronomers, like orchestra tuners, catch its harmonics — the redshift of distant galaxies, following the discovery of Edwin Hubble and the theoretical insight of Georges…

Think of a merry-go-round: the farther you sit from the center, the faster you're carried around. For a long time, astronomers assumed galaxies work the same way — stars at the edges should orbit more slowly than those near the center. But back in the 1970s, it turned out that in many spiral galaxies, the speed of stars barely drops with distance from the center.