Y. Guo

In a courtroom, there isn't always a video recording of the crime. Sometimes the verdict is based on witness testimony: what happened before, what happened after. That's exactly how physicists treated the signal GW250114, detected on January 14, 2025.

The Sun regularly produces explosions that hurl huge clouds of charged particles into space. Such a cloud travels toward Earth and can knock out satellites, disrupt radio communications, and even leave cities without electricity.

A thermos of liquid xenon cooled to minus 100 degrees Celsius. Inside are sensitive sensors that catch rare signals from dark matter particles. To bring these signals out, copper cables are usually used. But over the long haul, the signal weakens, and adjacent cables start 'cross-talking' — that's called crosstalk.

The Sun sometimes produces giant clouds of plasma that try to escape into space. But often they fail: an invisible magnetic cage keeps them near the surface. Such failed eruptions are called "trapped." Scientists built a computer model to understand exactly how this cage works.

After a supernova explosion, a neutron star neutron star remains: a city-sized ball of unimaginably dense matter, spinning hundreds of times per second. Any tiny bump on its surface would make it wobble like an off-balance spinning top, humming faintly through the fabric of space.

LIGO, Virgo, and KAGRA detectors act like giant microphones, listening in on gravitational waves — vibrations of space itself. The new GWTC-5.0 catalog recorded 161 black hole mergers, bringing the total count to 390 events.

Imagine a giant inflatable balloon with galaxies painted on it. As it inflates, the pattern stretches and neighboring dots move apart. The rate of that stretching is the Hubble constant. Astronomers usually catch light from distant stars and see how much it has reddened due to the stretching of space.

A huge bowl of water. Drop a stone into it — ripples spread across the surface. The fabric of spacetime works much the same way: when two massive stars merge, they create ripples — gravitational waves. These waves travel to Earth and are picked up by giant detectors like LIGO and Virgo.