From decades of astronomical observations, scientists know that most galaxies contain massive black holes at their centers.

F OR SOLDIERS at the front, electromagnetic defences are as vital as air: invisible when present, and disastrous when not. In ...

A second reason is that high frequency trading is embroiled in an arms race. And arms races are negative sum games. The arms in this case are not tanks and jets, but computer chips and throughput.

For interstellar communication, a particular range of radio frequencies, “microwaves” from 1 GHz to 10 GHz, are particularly good choices. At lower frequencies our galaxy emits prodigious amounts of ...