Is the solar system full of interstellar vagrants, passing unseen? For decades, it was all conjecture, interrupted only by the brief glimpses of objects such as 1I/’Oumuamua and 2I/Borisov. But with ...

In the quest for advanced civilizations, the universe is not often very forthcoming with its answers. But the recent suggestion by Harvard astrophysicist Avi Loeb has set astrophysics and SETI ...