14 replies to this topic

[Otto Piechowski]

An article published today in the magazine salon states that the Hubble telescope has discovered this galaxy which is 13.4 billion light years distant and has an age of 70 million years. I am confused. I thought the distance of 13,400,000,000 ly meant that that light has traveled for 13.4 billion years. Please help me understand what I am obviously misunderstanding. Thank you. Otto

 

The article can be found through this link   https://www.salon.co...verses-history/

Edited by Otto Piechowski, 27 December 2020 - 10:29 AM.

[jupiter122]

The Salon article is clearly wrong about the of age 70 million years and even the 13.4 billions light years figure is misleading (more on that below).  Generally, you have to be wary of science articles published in non-science magazines; the authors are often just reporting on science issues about which they lack even a basic understanding. I even saw one publication refer to the recent Jupiter-Saturn conjunction as the "north star."

 

As for reported light distances, bear in mind that the Universe is expanding. That means that an object, e.g., GN-z11, whose light has taken 13.4 billion years to reach us, will be considerably more distant than 13.4 billion light years, in fact, 32 billion years in the case of GN-z11.

 

Hope this helps.

 

Tim

[Otto Piechowski]

Yes Tim, your response helps. Otto

[Redbetter]

I assume that the age they are referring to would be an estimate of its age at the time the light was emitted.   This is the equivalent of someone sending a photograph of someone as a toddler, being lost in the mail, and to only reach someone many decades later when the original subject was elderly.

[bcgilbert]

Dear Otto

 

I’m also puzzled by the fact that Hubble can see anything at all at that distance.  There a two reasons for my saying this:     Firstly the Hubble Redshift with distance relationship should shift the narrow optical band down into the low infra red bands or even the top end of the RF bands.  The SKA low frequency array is intended to detect the 1420 MHz hydrogen lines red-shifted to approximately 100 MHz, applying that ratio to the optical regime results in the Hubble scope trying to detect 7 micron infra red, where have I gone wrong?  Could be electrons scatter RF more than light?

Secondly the attenuation in the IGM is always ignored.    I expect about 200 dB (10^20) of attenuation in the optical spectrum due to scattering off electrons, protons, carbon and iron particles, often referred to as dust.   The effective capture area of coulomb charges (electrons, protons) are enormously greater than their physical area, admittedly they mainly have a large area at RF much less so at optical.  All my statements are qualitative because the hard knowledge base on attenuation in the IGM has never been studied up until very recently.  Those who have studied it have been ridiculed, “the tired light group”, Zwicky, Reber, Hoyle, Arp, Alfen, Lerner, to name a few crackpots.  Dust in the IGM is a strong contender for dark matter in this crackpots opinion.

 

Barry.

[UT4Life]

I’m also puzzled by the fact that Hubble can see anything at all at that distance.  There a two reasons for my saying this:     Firstly the Hubble Redshift with distance relationship should shift the narrow optical band down into the low infra red bands or even the top end of the RF bands.  The SKA low frequency array is intended to detect the 1420 MHz hydrogen lines red-shifted to approximately 100 MHz, applying that ratio to the optical regime results in the Hubble scope trying to detect 7 micron infra red, where have I gone wrong?  Could be electrons scatter RF more than light?

 

HST is detecting the ultraviolet continuum of the galaxy, which has been redshifted into the near infrared. The redshifts of galaxies like this are measured with the Lyman alpha break, which is caused by strong absorption from the IGM at shorter wavelengths. Lyman alpha is at 121.6 nanometers, which is redshifted to ~1.5 microns, which is within the range of HST's infrared camera (WFC3/IR). It's not measuring H-alpha (which would be at 8ish microns as you say) or any emission lines.

 

Secondly the attenuation in the IGM is always ignored.    I expect about 200 dB (10^20) of attenuation in the optical spectrum due to scattering off electrons, protons, carbon and iron particles, often referred to as dust.   The effective capture area of coulomb charges (electrons, protons) are enormously greater than their physical area, admittedly they mainly have a large area at RF much less so at optical.  All my statements are qualitative because the hard knowledge base on attenuation in the IGM has never been studied up until very recently.  Those who have studied it have been ridiculed, “the tired light group”, Zwicky, Reber, Hoyle, Arp, Alfen, Lerner, to name a few crackpots.  Dust in the IGM is a strong contender for dark matter in this crackpots opinion.

If the extinction was that large in the optical then there is absolutely no way it would be visible in the ultraviolet. Dust is much stronger at shorter wavelengths. The galaxy is also detected by Spitzer at longer wavelengths, which measure the rest-frame optical. There is no reason to claim there is such large obsucration, and there's no way it's that large.

 

The study of the intergalactic medium is a big field in astronomy, certainly for the last 30 years with the Lyman alpha forest and 8-10 meter telescopes. Dust in the IGM cannot be dark matter. Firstly it can be measured with extinction in background objects. Secondly dark matter needs to be inside galaxies and galaxy clusters, it's not useful in the defuse IGM. Dust inside galaxies and clusters is heated by starlight, and so it is not dark. In standard cosmology baryonic dark matter (such as dust) is ruled out by limits imposed by primordial nucleosynthesis and the statistics of the cosmic microwave background.

[bcgilbert]

HST is detecting the ultraviolet continuum of the galaxy, which has been redshifted into the near infrared. The redshifts of galaxies like this are measured with the Lyman alpha break, which is caused by strong absorption from the IGM at shorter wavelengths. Lyman alpha is at 121.6 nanometers, which is redshifted to ~1.5 microns, which is within the range of HST's infrared camera (WFC3/IR). It's not measuring H-alpha (which would be at 8ish microns as you say) or any emission lines.

 

If the extinction was that large in the optical then there is absolutely no way it would be visible in the ultraviolet. Dust is much stronger at shorter wavelengths. The galaxy is also detected by Spitzer at longer wavelengths, which measure the rest-frame optical. There is no reason to claim there is such large obsucration, and there's no way it's that large.

 

The study of the intergalactic medium is a big field in astronomy, certainly for the last 30 years with the Lyman alpha forest and 8-10 meter telescopes. Dust in the IGM cannot be dark matter. Firstly it can be measured with extinction in background objects. Secondly dark matter needs to be inside galaxies and galaxy clusters, it's not useful in the defuse IGM. Dust inside galaxies and clusters is heated by starlight, and so it is not dark. In standard cosmology baryonic dark matter (such as dust) is ruled out by limits imposed by primordial nucleosynthesis and the statistics of the cosmic microwave background.

https://academic.oup.../2/1532/2417052

 

The CMB is the dust re-radiating thermalized starlight.

Dark energy is simply the dimming of the supernovae used as "standard candles"

 

Firstly it can be measured with extinction in background objects.

That is the equivalent of the attenuation of which I refer, just in other words?

 

https://arxiv.org/pd...-ph/0603833.pdf

 

Barry

Edited by bcgilbert, 06 January 2021 - 11:25 AM.

[UT4Life]

https://academic.oup.../2/1532/2417052

 

The CMB is the dust re-radiating thermalized starlight.

Dark energy is simply the dimming of the supernovae used as "standard candles"

That paper is not talking about the CMB, it's talking about the EBL. The EBL is the optical and infrared extragalactic backgrounds, neither of which are related to the CMB. If you look at figure 3 in that paper you will see the long wavelength component of the EBL peaks at 150 microns. The CMB however peaks at around 1 mm wavelength (1000 microns). Clearly these aren't the same backgrounds. See figure 1 of this paper showing the difference:

 

https://ui.adsabs.ha.....005F/abstract

 

Claiming the CMB is dust raises a huge number of questions. For example the angular powerspectra show rich structure, the form of these features were actually predicted by standard theory. Without a model that can describe these anisotropies any alternative explanation for the CMB just isn't competitive in explaining observations.

 

https://ned.ipac.cal...ott/Scott4.html

 

Dark energy is simply the dimming of the supernovae used as "standard candles"

That is the equivalent of the attenuation of which I refer, just in other words?

 

https://arxiv.org/pd...-ph/0603833.pdf
 

 

And no dark energy is not just found in supernovae data. There has been evidence from multiple probes for several years, both in baryon acoustic osculations and things like the ISW effect.

 

https://ui.adsabs.ha...00487L/abstract

 

Also the amounts of dust they are talking about in the paper you posted are tiny, less than a tenth of a mag. Nothing like "10^20".

[bcgilbert]

That paper is not talking about the CMB, it's talking about the EBL. The EBL is the optical and infrared extragalactic backgrounds, neither of which are related to the CMB. If you look at figure 3 in that paper you will see the long wavelength component of the EBL peaks at 150 microns. The CMB however peaks at around 1 mm wavelength (1000 microns). Clearly these aren't the same backgrounds. See figure 1 of this paper showing the difference:

 

https://ui.adsabs.ha.....005F/abstract

 

Claiming the CMB is dust raises a huge number of questions. For example the angular powerspectra show rich structure, the form of these features were actually predicted by standard theory. Without a model that can describe these anisotropies any alternative explanation for the CMB just isn't competitive in explaining observations.

 

https://ned.ipac.cal...ott/Scott4.html

 

 

And no dark energy is not just found in supernovae data. There has been evidence from multiple probes for several years, both in baryon acoustic osculations and things like the ISW effect.

 

https://ui.adsabs.ha...00487L/abstract

 

 

 

Also the amounts of dust they are talking about in the paper you posted are tiny, less than a tenth of a mag. Nothing like "10^20".

More on "dust"

 

https://arxiv.org/pd...-ph/0603833.pdf

 

 

Barry

Edited by bcgilbert, 13 January 2021 - 10:17 PM.

[UT4Life]

More on "dust"

 

https://arxiv.org/pd...-ph/0603833.pdf

 

That's the same paper you already posted. See my previous reply.

[bcgilbert]

That's the same paper you already posted. See my previous reply.

Try this one

 

https://dash.harvard....pdf?sequence=1

 

Barry

[bcgilbert]

My take on dust

 

The biggest problem for all "tired light theories", was and still is, the “the photon”,  no one can find a method, or mechanism for the photon to loose a small amount of energy, in other words the photon cannot be split or subdivided.  This is obviously true for "photons".      However if you temporarily suspend your belief in the photon, and think of light as a Maxwellian wave packet then there is no problem in light loosing a small, or any arbitrary amount of energy to a dust particle.    The particle can translate or move due to radiation pressure, while simultaneously absorbing energy into its structure and agitating the molecules in the dust, also some energy can be reflected or scattered off the particle.   The particle will now be able to radiate some of this newly acquired energy as heat in the infra red region.   The spectrum  could have two components of observed temperature:  firstly the temp. due to translation, secondly a form of black-body radiation due to vibrating molecules in the particle. The wave front of the wave packet will have lost some energy locally and will now be at a slightly lower frequency (frequency is proportional to energy).     In other words the forward wavefront will be “reddened” and slightly reduced in amplitude, or“attenuated”.   This form of reddening is not to be confused with Rayleigh scattering or reddening, but they can coexist for particles less than a half wavelength of the light of interest.    The reddening of the sun and moon due to bush fire smoke is of the fore mentioned type and not Rayleigh reddening.

 

Barry

 

 

[BillP]

A Wikipedia snippet on this galaxy...

 

GN-z11 is a high-redshift galaxy found in the constellation Ursa Major. The discovery was published in a paper headed by P.A. Oesch and Gabriel Brammer (Cosmic Dawn Center). GN-z11 is currently the oldest and most distant known galaxy in the observable universe. GN-z11 has a spectroscopic redshift of z = 11.09, which corresponds to a proper distance of approximately 32 billion light-years (9.8 billion parsecs). The object's name is derived from its location in the GOODS-North field of galaxies and its high cosmological redshift number (GN + z11). GN-z11 is observed as it existed 13.4 billion years ago, just 400 million years after the Big Bang; as a result, GN-z11's distance is sometimes inappropriately reported as 13.4 billion light-years, its light-travel distance measurement.

 

A 1/4/2021 paper nailing the red shift - https://astrobites.o...04/gn-z11-spec/

Edited by BillP, 25 January 2021 - 06:11 PM.

[UT4Life]

Try this one

 

https://dash.harvard....pdf?sequence=1

 

Barry

That paper is also not claiming the CMB is produced by dust. In fact the constrain the contribution from intergalactic dust to be very small indeed.

 

My take on dust

 

The biggest problem for all "tired light theories", was and still is, the “the photon”,  no one can find a method, or mechanism for the photon to loose a small amount of energy, in other words the photon cannot be split or subdivided.  This is obviously true for "photons".      However if you temporarily suspend your belief in the photon, and think of light as a Maxwellian wave packet then there is no problem in light loosing a small, or any arbitrary amount of energy to a dust particle.    The particle can translate or move due to radiation pressure, while simultaneously absorbing energy into its structure and agitating the molecules in the dust, also some energy can be reflected or scattered off the particle.   The particle will now be able to radiate some of this newly acquired energy as heat in the infra red region.   The spectrum  could have two components of observed temperature:  firstly the temp. due to translation, secondly a form of black-body radiation due to vibrating molecules in the particle. The wave front of the wave packet will have lost some energy locally and will now be at a slightly lower frequency (frequency is proportional to energy).     In other words the forward wavefront will be “reddened” and slightly reduced in amplitude, or“attenuated”.   This form of reddening is not to be confused with Rayleigh scattering or reddening, but they can coexist for particles less than a half wavelength of the light of interest.    The reddening of the sun and moon due to bush fire smoke is of the fore mentioned type and not Rayleigh reddening.

 

Barry

But reddeing is not redshift. Redding just preferentially removes blue light, redshift is the features in the spectrum moving to longer wavelengths. Having dust absorb the light and the reimit it would a) destroy the original spectrum and b) scatter the light in angle. That means distant objects like quasars would be blurred, and their spectra would be replaced by the blackbody emission from the dust. This is not what is observed.

[bitnick]

UT4Life: Before replying to bcgilbert again, take a look at some of his earlier discussions on this forum: Here's one example, and here's another one. In short: don't waste your time.