Most accurate cosmic clocks show unexpected instability

In all the cosmos, pulsars are the most precise long-term way to measure time.

Each time these magnetized neutron stars complete a rotation, a pulse of radiation emerges.

When pulses intersect your line-of-sight, you’ll observe rapid, periodic bursts.

The fastest-spinning ones, millisecond pulsars, are the most accurate and stable pulsars for timekeeping purposes.

The first pulsar was found in 1967, with the first millisecond pulsar discovered in 1982.

Only with subsequent advances did laboratory-based atomic clocks surpass pulsars in timekeeping precision.

For millisecond pulsars, the average time between pulses can be known to ~15 significant figures.

With 100+ pulses-per-second, that translates to microsecond-level precision over multi-decade timescales.

However, on rare occasions, pulsars “glitch” in abrupt fashion.

When glitching, their rotational speed suddenly accelerates.

Were glitches neutron star-quakes?

If denser material migrated towards the rotation axis, the rotational period would shorten.

Recently observed glitches, once thought rare, contradict this model.

The closest millisecond pulsar, PSR J0437-4715, is just 510 light-years away.

It possesses a white dwarf companion.

Two consecutive glitching events were recently discovered: in 2017 and 2022.

Combined with PSR 1713+0747’s similar glitch, polarization-based analyses favor magnetospheric, not seismic, origins.

Perhaps millisecond pulsars aren’t as stable, long-term, as once believed.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.

This article is featured on Big Think.