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marcus

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**In 1998 "Hubble volume" meant a cube 12 billion LY on a side**

Majin asked what is hubble volume.

I did a google search and found that in 1998 there was

a computer simulation study at one of the Max Planck institutes

which simulated a cube

12 billion LY on a side (comoving distance)

other sites indicated the simulation cube was 3/0.71 billion parsecs on a side

which is slightly different---about 13.8 billion LY on a side

they use the symbol h = H

_{0}/(100 km/s per Mpc)

which has now been determined to be 0.71

and they make the cube 3/h billion pc on a side

Back in 1998 and before there was wide uncertainty about the hubble parameter like 50-100 km/sec per megaparsec

corresponding to widely varying ideas of the Hubble length.

Now the estimate for the Hubble length is reasonably stable

at around 13.7 or 13.8 billion LY

According to today's notion of the Hubble length, the volume should be a cube 13.7 billion LY on a side.

They indicated that this cube was NOT the volume of the observable universe but, instead, was "a significant fraction" of it.

In fact the present volume of the observable universe is several times the Hubble volume and the two should not be confused.

(But it appears that the two are being confused in a recent

scientific american article!)

There is a lot of google stuff on hubble volume but it mostly

involves this simulation project.

I found a journal article---very technical---with hubble volume in a technical sense of L^3, where L is the hubble length. But that

was kind of drowned out by links to the simulation projects

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