Comments on: Across the Universe

By: Rob Frost

Rob Frost — Tue, 26 May 2015 18:04:45 +0000

Thanks very much for the reply, I appreciate your time. Sorry I did’t spell out the paradox very clearly. The paradox is that the light emitted at the big bang was right next to us when it was emitted. Now it arrives, 13.7 billion years later, having been emitted right next to us all that time ago. A reformulation of Hubble’s law would be stronger under Occam’s razor than inflation.

By: Brian Koberlein

Brian Koberlein — Sun, 24 May 2015 20:21:00 +0000

Most likely. Popular press usually infers distance by age.

By: Wolfgang

Wolfgang — Sun, 24 May 2015 20:05:46 +0000

In some news in the internet I’ve found the message regarding the brightest galaxy ever seen – WISE J224607.57-052635.0. All news says that the galaxy is 12.5 billion light years away. Is this the same situation as you have described in the text above? That means the light needs 12.5 billion years to reach the earth and the current distance is much larger?

By: Brian Koberlein

Brian Koberlein — Tue, 19 May 2015 12:48:20 +0000

It’s not that things accelerate with the space their in, but rather that the space between objects expands over time, giving the relative motion. It might seem odd, but keep in mind in general relativity space is not a fixed absolute, but can be warped and stretched.

By: Rob Frost

Rob Frost — Tue, 19 May 2015 09:15:50 +0000

If, as big bang theory states, at the moment of the big bang, we were right next to the contents of EGS-zs8-1, and now, 13.7 billion years later, we are 26 billion light years away, then RELATIVE TO US, the galaxy has receded 26 billion light years in 13.7 billion years, thereby receding from us at twice the speed of light. This means that current theory considers things to accelerate with the space in which they are located. Is this correct? If not, are you able to resolve the paradox?

By: Emmet Ford

Emmet Ford — Sat, 16 May 2015 02:58:52 +0000

That was a good read.

By: cassiopeiancustardcream

cassiopeiancustardcream — Fri, 15 May 2015 23:47:13 +0000

Hi Ramiro, this quote is quite apt in that everything does depend on the color of this distant galaxy. Astronomers can often deduce a galaxy’s distance from Earth by very carefully measuring its color in visible and infrared light.
Astronomers were able to identify the galaxy EGS-zs8-1 as a high redshift candidate in survey images taken by the Hubble and Spitzer space telescopes. Considering color alone it appeared to be one of the brightest and most massive objects found by astronomers in the early universe. However, sometimes color can be deceptive. Perhaps EGS-zs8-1 is really a peculiar red galaxy with a much lower redshift.
To confirm the high redshift and take the current distance record, the galaxy needs to have its redshift measured by spectroscopy. This is why some of the very distant galaxies seen in Hubble’s Frontier Fields survey (thanks to gravitational lensing) do not hold the record even though their redshift may be z~8-1z~10. No one has yet been able to confirm the redshift estimate that was obtained by studying images from HST.
Spectroscopy of the early Universe is no easy task. Both Hubble and Spitzer are equipped to carry out spectroscopic measurements but their instruments are not sensitive enough to target extremely distant faint galaxies seen at very early cosmic times. This is why astronomers are patiently waiting for the new James Webb Space Telescope, which will have the capabilities to carry out these very challenging measurements.
However, in this particular case the astronomers were able to successfully confirm the high (record-breaking) redshift of EGS-zs8-1 , by using a relatively new, powerful spectrometer called MOSFIRE (Multi-Object Spectrograph for Infrared Exploration) on the Keck 10 meter Telescope in Hawaii. MOSFIRE has a sensitive state-of-the-art detector and electronics system, which allowed the astronomers carrying out this research to make observations of this distant galaxy and make the z~7.7 measurement.
I think the complete quatrain Ramiro quotes says:
“In this treacherous world, nothing is truth or lie, everything depends on the color of the glass through which you look “.
I’d like to amend this text if we’re applying it to the Universe:
“In this treacherous Universe, nothing is truth or lie, everything depends on the sensitivity of the spectrometer that is attached to the telescope through which you look”.

By: ramiro escobar nurnberg

ramiro escobar nurnberg — Fri, 15 May 2015 19:02:43 +0000

All that’s said above makes me think that Ruben Dario was not too far off when he said : “nada es verdad o mentira, todo depende del cristal con que se mira…”

By: Brian Koberlein

Brian Koberlein — Fri, 15 May 2015 12:54:50 +0000

That it is. Corrected. Thanks.

By: Jean Tate

Jean Tate — Fri, 15 May 2015 12:07:28 +0000

Um, a z of 0 is ‘local’, or here. Redshift is defined as the ratio of observed wavelength over (divided by) ‘restframe’ wavelength minus 1.

@ Amir: Ned Wright’s CosmoCalc is perhaps the best (google it); in the geometry of the universe – which is based on General Relativity – ‘distance’ is no longer simple, there are several different ‘distances’, for the same galaxy!

By: Amir

Amir — Fri, 15 May 2015 11:24:58 +0000

Can you post a graph or a table that converts between z factor and the distances (comoving, coangular and current)?

Also, is this influenced by the distribution of dark matter and dark energy, so depends on the direction of the object?

Thanks for your great work on this blog.