Comments on: New burst vaporizes cosmic distance record

By: BA Review: Star Trek

BA Review: Star Trek — Sun, 17 May 2009 18:39:59 +0000

[...] had Abrams called me, I would’ve told him to use a gamma-ray burst, not a supernova. GRBs are like super-supernovae, where instead of the explosion moving outward in [...]

By: BA Review: Star Trek | Bad Astronomy | Discover Magazine

BA Review: Star Trek | Bad Astronomy | Discover Magazine — Sat, 09 May 2009 05:32:50 +0000

[...] had Abrams called me, I would’ve told him to use a gamma-ray burst, not a supernova. GRBs are like super-supernovae, where instead of the explosion moving outward in [...]

By: DrFlimmer

DrFlimmer — Thu, 30 Apr 2009 18:00:00 +0000

I was wondering why you had not been making any comments there. I registered on day #1 and I had no problem.

An honour being missed, too bad that it does not help. The next problem is that I cannot try again with the same nick and the same address, because it is already used (of course). Dammit.

By: Tom Marking

Tom Marking — Thu, 30 Apr 2009 17:01:53 +0000

@scibuff “For redshifts greater than 0.8, the relationship between redshift and distance is more complex, as account has to be made of many other factors. This is the distance formula”

Oooo, that’s a very nasty integration. The reciprocal of a square root of a cube plus a square. I guess that’s what computers are for. Thanks for the calculator.

Playing around with some of the numbers in the calculator I get:

H0 = 71
Omega-M = 0.27
Omega-Vac = 0.73
Z = 8.2
Current age of universe = 13.666 Gyr
Initial age of universe when photon started = 0.63 Gyr
light travel time = 13.035 Gyr
Comoving radial distance = 30.017 Gly
Comoving volume within redshift Z = 3265.010 cubic Gpc
Luminosity distance = 276.142 Gly

The path length of the photon is 13.035 billion light-years in this case. Changing the parameters I find it very hard to come up with a photon path length of more than ~30 billion light-years and if I do the age of the universe is longer than ~13 billion years. So it doesn’t seem that 46.5 billion light-years is a credible number. Maybe that is the comoving distance, not the path length of the photon.

By: EJ

EJ — Wed, 29 Apr 2009 17:38:07 +0000

@Tom Marking – thanks a lot, that was a good explanation. I’d assumed 46.5 billion ly was predicated on assuming some specific cosmological model, but I couldn’t figure out which one.

By: IVAN3MAN

IVAN3MAN — Wed, 29 Apr 2009 17:22:09 +0000

@ DrFlimmer,

I was wondering why you had not been making any comments there. I registered on day #1 and I had no problem.

By: DrFlimmer

DrFlimmer — Wed, 29 Apr 2009 17:08:20 +0000

@ Tom Marking:

Is your life so boring or how long did you need to make all these calculations?
Nontheless, they are very interesting, thanks a lot!

Btw: I hate it that I cannot register on Universe Today for some reasons (I don’t receive the confirmation mail and I tried two different addresses).