Chanced upon this rather interesting application of gravitational waves to determine Hubble constant. Thats definitely one uses I would never have thought of lmao. Measuring intervening density ( underdense, overdense) I have thought of a few times but not Hubble constant.

https://arxiv.org/pdf/2503.01997

It is nice to see that this also applies the evolutionary density to Hubble constant via

E(z)=\sqrt{\Omega_r(1+z)^4+\Omega_m(1+z)^3+\Omega_k(1+z^2)+\Omega_\Lambda}

which is used in a wide range of measurement related equations for far field measurements. (Beyond Hubble horizon ). Note use of E here is not energy, it is expansion rate at a given Z instead of using H_z and avoiding confusion with H_o) Hubble constant today on latter with prior as Hubble constant as function of redshift.

For late times such as universe in Lambda dominant era and curvature term k=0 the above expression simplifies to

E_z=\sqrt{\Omega_m(1+z)^3+\Omega_\Lambda}

Edited 9 hours ago9 hr by Mordred

4 hours ago, Mordred said:

gravity waves

You mean gravitational waves ;)

1 hour ago, Markus Hanke said:

You mean gravitational waves ;)

thanks was worried on title length at the time forgot to edit it after initial post. Corrected above

1 minute ago, Mordred said:

thanks was worried on title length at the time forgot to edit it after initial post. Corrected above

It's not only in the title...

6 hours ago, Mordred said:

Chanced upon this rather interesting application of gravity waves

Lmao thanks

16 minutes ago, Genady said:

It's not only in the title...

Must have been half asleep lmao