One of the weird things about being a senior scientist is seeing all the things you thought would never happen actually happen. It was twenty years ago this summer that I took the last of the data for my Ph.D. Back then, if you’d asked me if we’d ever be able to study the universe’s first 400,000 years or map the universe in anything other than light, I would have raised a skeptical eyebrow and said, “No. Physics doesn’t work like that.”

The thing is, physics does work like that. Light doesn’t, but what we can’t do with light, we can do with gravity. 

Back then, as we all watched LIGO fail to hit deadline after deadline, we just didn’t have a complete appreciation for the fact that we can view the universe in gravity as well as in light, and humans can actually – given enough decades and dollars – build equipment that can detect gravitational waves.

We are not quite a decade into this new era of gravitational wave detection, and already folks are pushing this new area of physics in crazy new directions.

Case in point: Today, I learned the new term “GRADAR”. It’s like radar, but instead of using radio light to see our surroundings, it uses gravity.

A new paper coming out in Physical Review Letters by Craig Copi and Glenn Starkman defines how gravitational waves can be used to map the insides of stars… maybe. After doing a lot of maths that Copi describes as “a very hard calculation”, they were able to determine that the glints of gravitational waves are larger than expected and might be detectable someday in the future. Astronomer Maya Fishback provides this perspective, saying: The whole story of gravitational wave detection has been like that. It was a struggle to do all the math needed to understand their measurements, but now the field is taking off. This is the time to really be creative with gravitational waves.

And I am enjoying watching other folks do the maths I am so grateful I didn’t have to do for homework assignments in grad school. It is amazing how science changes.

As a reminder – there are Ph.D. astronomers out there who pre-date the discovery of galaxies.

More Information

Gravitational wave ‘radar’ could help map the invisible universe (Science News)

“Gravitational Glint: Detectable Gravitational Wave Tails from Stars and Compact Objects,” Craig Copi and Glenn D. Starkman, 2022 June 22, Physical Review Letters