<p>The current redshift record is set by the <a href="https://en.wikipedia.org/wiki/JADES-GS-z13-0" rel="nofollow noreferrer">JADES galaxies</a>. The highest-redshift one at <span class="math-container">$z = 13.20$</span> isn't too convincing tbh, but there's one at 12.6 that looks better, and the one at <span class="math-container">$z = 11.6$</span> should be good enough. But if we go with z ~ 13, then according to the answer you link to, the volume of the &quot;observed&quot; Universe is <span class="math-container">$\simeq150\,000\,\mathrm{Glyr}^3$</span>.</p>
<p>In that answer, I equated that to 10% more than in the pre-JWST era. However, this was based on the prior redshift record of <a href="https://en.wikipedia.org/wiki/GN-z11" rel="nofollow noreferrer">GN-z11</a>, which had been measured to <span class="math-container">$z\simeq11.1$</span> (<a href="https://ui.adsabs.harvard.edu/abs/2016ApJ...819..129O/abstract" rel="nofollow noreferrer">Oesch et al. 2016</a>). But that redshift was, as is the case with the JADES galaxies, measured in a somewhat imprecise way, namely by the spectral <em>break</em> at the Lyman α line. That is, there wasn't any spectral <em>lines</em>, but just the break that comes from the intergalactic medium absorbing any radiation bluer than Lyman α, and the exact wavelength of this break depends on many obscure factors.</p>
<p>With JWST, it is now possible to observe such lines from GN-z11, and its redshift has been established at <span class="math-container">$z=10.60$</span> (<a href="https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..88B/abstract" rel="nofollow noreferrer">Bunker et al. 2023</a>). This actually means that the observed Universe was a little smaller before than we thought. It seems a little like cheating, but this in turn means than the fractional increase is a little larger, so 13% instead of 10%.</p>
<p>Gravitational lensing does indeed help observing more distant galaxies, and for this reason JWST has targeted several massive galaxy clusters, to look for distant background galaxies. These galaxies were unlensed though.</p>
<p>The plot below shows the probed volume as a function of the redshift of the most distant known galaxy. Since the very first galaxies are thought to form at <span class="math-container">$z\simeq20\text{–}30$</span>, an increase of more than <span class="math-container">$\sim50\%$</span> is unlikely. But stay tuned; I'll update this plot along the way :)</p>
<p><a href="https://i.sstatic.net/FCelt.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/FCelt.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2024-01-28T16:00:44.480Z
Is redshift value directly propotional to distance from earth?
Vaelus
CC BY-SA 4.0
2024-01-28T20:30:32.593Z
@Vaelus I guess this is a separate question, but no, unfortunately not. The redshift reflects the relative increase of the size of the Universe. Because the fractional increase is larger when the Universe increases from, say, 5% to 10% than when it increases from 95% to 100%, photons redshifted more in the past. Moreover, the expansion hasn't been constant throughout the history of the Universe: in the beginning it decelerated, but later it started accelerating. So the exact relation requires a model of the expansion history, i.e. (numerical integration of) the Friedmann equation.
pela
CC BY-SA 4.0
2024-01-29T11:27:57.280Z
I guess this is all clear to physicists, but... is z scaled such that "z=11.6" corresponds "11.6 billion (light)years"? If not, what is the radius of the observable universe atm?
AnoE
CC BY-SA 4.0
2024-01-29T13:28:28.733Z
@AnoE No, it's unfortunately far from linear. The radius of the (theoretically) observable Universe — which would correspond to z = infinity — is just over 46 billion lightyears. Hoping that some self-promotion will be judged mildly, let me direct you to Fig. 1 of [Laursen (2013)](https://arxiv.org/abs/2309.02486) which shows the relation (as well as some other relations that scale with z) up to z = 18.
pela
CC BY-SA 4.0
2024-01-29T13:51:26.240Z
Thanks @pela! I think nobody will judge you for self-promotion if it helps the answer. The chart in the top left corner of pg3 of that paper would fit into your answer very well, assuming you have the copyright for it and want to add it. ;)
AnoE
CC BY-SA 4.0
2024-01-30T14:32:23.933Z
@AnoE Thanks! To be honest, I don't really know if I have the rights to the diagram. Although I produced it myself, I may have handed over the rights to Springer (the publishing company), along with my left kidney and my firstborn. But I suppose I'm allowed to make a new one, so I'll do that :)
pela
CC BY-SA 4.0
2024-01-30T23:50:23.160Z
@pela thanks!  My mind spins when I think of how small we thought the universe was prior to coming to understand that Andromeda was a galaxy and so far away (for that time)... and comparing that to what we now know and are coming to understand.
BradV
CC BY-SA 4.0
2024-01-30T23:53:59.500Z
@BradV You're welcome :) Yes, space is ridiculously, unnecessarily big…
pela
CC BY-SA 4.0
2024-01-27T22:22:14.707Z
2024-01-30T22:44:50.777Z
2024-01-30T22:44:50.777Z
pela
<p>On April 2 2022 I asked for estimates of expected results. <a href="https://astronomy.stackexchange.com/questions/48985/how-much-larger-will-the-observable-by-us-universe-be-when-jwst-becomes-operat">How much larger will the &quot;observable by us&quot; universe be when JWST becomes operational?</a>.</p>
<p>As of Jan 27 2024 with JWST operational for about 18 months how much larger (percent) is the observable sphere? I would not consider CMB to be the prior limit.</p>
<p>Would gravitational lensing be suitable for inclusion in this?</p>

CC BY-SA 4.0
2024-01-27T17:16:45.330Z
Can you perhaps use the values and estimates in the question, with the data "before z="10.6" after z="13.2"  and so at the "conservative" end of the scale, and a volume increase of about 10%
James K
CC BY-SA 4.0
2024-01-28T15:20:46.243Z
@JamesK Thanks, but I do not feel I have solid enough grasp of this subject to provide limits. I thought I'd leave it to the SMEs here (Subject Matter Experts) to provide currently accepted values for "before" and "after" and argue for or against positions.
BradV
CC BY-SA 4.0
2024-01-29T11:09:14.417Z
@BradV I realize my answer below pretty much is the same as [the comment](https://astronomy.stackexchange.com/questions/48985/how-much-larger-will-the-observable-by-us-universe-be-when-jwst-becomes-operat#comment119150_48987) I gave below my previous answer. Nevertheless, that's the current state of affairs. But I'm quite positive that the distance record will be broken once again :)
pela
CC BY-SA 4.0
2024-01-30T22:45:43.963Z
@BradV I added a figure that show you how the volume increases with observed redshift.
pela
<observable-universe><james-webb-space-telescope>
As of now how much larger is our practically observable universe compared to just prior to JWST becoming operational
BradV
# As of now how much larger is our practically observable universe compared to just prior to JWST becoming operational

(Asked by: username_0 on 2024-01-27)

On April 2 2022 I asked for estimates of expected results. [How much larger will the "observable by us" universe be when JWST becomes operational?](https://astronomy.stackexchange.com/questions/48985/how-much-larger-will-the-observable-by-us-universe-be-when-jwst-becomes-operat).

As of Jan 27 2024 with JWST operational for about 18 months how much larger (percent) is the observable sphere? I would not consider CMB to be the prior limit.

Would gravitational lensing be suitable for inclusion in this?

**Tags:** observable-universe, james-webb-space-telescope
> **Comments:**
> **username_1**: Can you perhaps use the values and estimates in the question, with the data "before z="10.6" after z="13.2"  and so at the "conservative" end of the scale, and a volume increase of about 10%  
> **username_0**: @JamesK Thanks, but I do not feel I have solid enough grasp of this subject to provide limits. I thought I'd leave it to the SMEs here (Subject Matter Experts) to provide currently accepted values for "before" and "after" and argue for or against positions.  
> **username_2**: @BradV I realize my answer below pretty much is the same as [the comment](https://astronomy.stackexchange.com/questions/48985/how-much-larger-will-the-observable-by-us-universe-be-when-jwst-becomes-operat#comment119150_48987) I gave below my previous answer. Nevertheless, that's the current state of affairs. But I'm quite positive that the distance record will be broken once again :)  
> **username_2**: @BradV I added a figure that show you how the volume increases with observed redshift.  

---

## 1 answers

### Answer by username_2 on 2024-01-27. Score: 19 | Accepted answer

The current redshift record is set by the [JADES galaxies](https://en.wikipedia.org/wiki/JADES-GS-z13-0). The highest-redshift one at $z = 13.20$ isn't too convincing tbh, but there's one at 12.6 that looks better, and the one at $z = 11.6$ should be good enough. But if we go with z ~ 13, then according to the answer you link to, the volume of the "observed" Universe is $\simeq150\,000\,\mathrm{Glyr}^3$.

In that answer, I equated that to 10% more than in the pre-JWST era. However, this was based on the prior redshift record of [GN-z11](https://en.wikipedia.org/wiki/GN-z11), which had been measured to $z\simeq11.1$ ([Oesch et al. 2016](https://ui.adsabs.harvard.edu/abs/2016ApJ...819..129O/abstract)). But that redshift was, as is the case with the JADES galaxies, measured in a somewhat imprecise way, namely by the spectral *break* at the Lyman α line. That is, there wasn't any spectral *lines*, but just the break that comes from the intergalactic medium absorbing any radiation bluer than Lyman α, and the exact wavelength of this break depends on many obscure factors.

With JWST, it is now possible to observe such lines from GN-z11, and its redshift has been established at $z=10.60$ ([Bunker et al. 2023](https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..88B/abstract)). This actually means that the observed Universe was a little smaller before than we thought. It seems a little like cheating, but this in turn means than the fractional increase is a little larger, so 13% instead of 10%.

Gravitational lensing does indeed help observing more distant galaxies, and for this reason JWST has targeted several massive galaxy clusters, to look for distant background galaxies. These galaxies were unlensed though.

The plot below shows the probed volume as a function of the redshift of the most distant known galaxy. Since the very first galaxies are thought to form at $z\simeq20\text{–}30$, an increase of more than $\sim50\%$ is unlikely. But stay tuned; I'll update this plot along the way :)

[![enter image description here](https://i.sstatic.net/FCelt.png)](https://i.sstatic.net/FCelt.png)

> **Comments:**
> **username_3**: Is redshift value directly propotional to distance from earth?  
> **username_2**: @Vaelus I guess this is a separate question, but no, unfortunately not. The redshift reflects the relative increase of the size of the Universe. Because the fractional increase is larger when the Universe increases from, say, 5% to 10% than when it increases from 95% to 100%, photons redshifted more in the past. Moreover, the expansion hasn't been constant throughout the history of the Universe: in the beginning it decelerated, but later it started accelerating. So the exact relation requires a model of the expansion history, i.e. (numerical integration of) the Friedmann equation.  
> **username_4**: I guess this is all clear to physicists, but... is z scaled such that "z=11.6" corresponds "11.6 billion (light)years"? If not, what is the radius of the observable universe atm?  
> **username_2**: @AnoE No, it's unfortunately far from linear. The radius of the (theoretically) observable Universe — which would correspond to z = infinity — is just over 46 billion lightyears. Hoping that some self-promotion will be judged mildly, let me direct you to Fig. 1 of [Laursen (2013)](https://arxiv.org/abs/2309.02486) which shows the relation (as well as some other relations that scale with z) up to z = 18.  
> **username_4**: Thanks @pela! I think nobody will judge you for self-promotion if it helps the answer. The chart in the top left corner of pg3 of that paper would fit into your answer very well, assuming you have the copyright for it and want to add it. ;)  
> **username_2**: @AnoE Thanks! To be honest, I don't really know if I have the rights to the diagram. Although I produced it myself, I may have handed over the rights to Springer (the publishing company), along with my left kidney and my firstborn. But I suppose I'm allowed to make a new one, so I'll do that :)  
> **username_0**: @pela thanks!  My mind spins when I think of how small we thought the universe was prior to coming to understand that Andromeda was a galaxy and so far away (for that time)... and comparing that to what we now know and are coming to understand.  
> **username_2**: @BradV You're welcome :) Yes, space is ridiculously, unnecessarily big…  

---

