A pulsar is a dead star that spins and emits radio pulses like a lighthouse. If a pulsar has a companion, they whirl around a common center of gravity. When the orbit is tight, the orbital period is less than a day, and the pulsar's signal starts to "wobble": because of the motion, the star alternately approaches and recedes from us, and the pulse frequency shifts like the siren of a passing car. Standard searches for such systems are like trying to hear a whisper in a noisy hall — the signal simply gets lost.
The new method works like a smart interpreter who breaks rapid speech into short phrases and tracks how they change. It divides the signal into equal-length chunks, then uses a special algorithm (called a hidden Markov model) to build the most likely chain of frequency changes. This resembles a game of "guess the next word," except the words are radio pulse frequencies. The method proved fast: the computer processes data in seconds, not hours.
Why does this matter? Tight binaries with pulsars are natural laboratories for testing the laws of gravity. In such systems, we can observe how spacetime curves, and even find a pulsar–black hole pair, which has yet to be caught. The new tool will speed up the search and may lead to the discovery of rare objects we can only guess about.
The fastest known pulsar spins 716 times per second — faster than a kitchen blender.
In the movie Interstellar, heroes travel to a planet near a black hole where time runs slower; tight binaries with pulsars are a real way to test such effects.