James Webb Space Telecope image

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 AllanMac 12 Jul 2022

The first near-infrared image from the James Webb Telescope shows galaxy clusters as they were 13bn years ago. It’s an amazing image, but there’s something I don’t understand and hope someone on UKC has an answer!: The longest dimension of the galaxies seem to loosely follow a concentric smeared ‘grain’ around a bright central point, almost like an optical aberration. The Hubble image of the same cluster, though more distant and not as detailed, shows similar patterning in the smaller galaxies.

It can’t be long exposure movement, because some point sources have remained as points of light and are not smeared at all.

If this is not an imaging aberration, what else could be the explanation? Gravitational lensing or something?


 ThunderCat 12 Jul 2022
In reply to AllanMac:

I can't answer you question. But a comment on radio 4 this morning about this caught my attention. Hold a grain of sand up to the sky at arms length. The area of sky it covers is roughly the area of space the telescope was looking at to produce that image.

It bends my head. Its exactly this type of jaw dropping scale and grandeur that the word "awesome" was designed for. 

Post edited at 11:45
 Lhod 12 Jul 2022
In reply to AllanMac:

With the disclaimer that I'm no expert - I understand that it's gravitational lensing. I.e. The red warped galaxies are very far away / long ago and the light from them is bending around the large galaxy cluster in the relative foreground. Happy to be corrected. 

 felt 12 Jul 2022
In reply to AllanMac:

Probably just a fingerprint smudge on the lens. I'll pop along later with a cloth if I've got time before school pickup.

 graeme jackson 12 Jul 2022
In reply to ThunderCat:

> I can't answer you question. But a comment on radio 4 this morning about this caught my attention. Hold a grain of sand up to the sky at arms length. The area of sky it covers is roughly the area of space the telescope was looking at to produce that image.

Radio 4 have nicked that quote from the original Hubble Deep field image...

"Hubble's first deep field image was unveiled on Jan. 15, 1996, at a meeting of the American Astronomical Society. Hubble was aimed at an empty region of space in the northern constellation Ursa Major, imaging an area about the size of a grain of rice held at arm's length. The Wide Field and Planetary Camera 2 snapped 342 exposures over 10 days between Dec. 18 and 28, 1995."

OOPS - also from NASA..

"Webb’s image covers a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground – and reveals thousands of galaxies in a tiny sliver of vast universe"

Maybe someone in NASA has been holding a grain of rice at arms length for 26 years. 

Post edited at 15:07
 graeme jackson 12 Jul 2022
In reply to Lhod:

> With the disclaimer that I'm no expert - I understand that it's gravitational lensing. I.e. The red warped galaxies are very far away / long ago and the light from them is bending around the large galaxy cluster in the relative foreground. Happy to be corrected. 

Yep. That's essentially what NASA have said.  The foreground cluster is 'only' 4.6BN years old whereas due to gravitational lensing the red swooshy ones are much much older. (why do I hear the voice of Father Ted right now?)

https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepes...

 Tringa 12 Jul 2022
In reply to AllanMac:

Just a fantastic image and nearly everything in the shot is a galaxy!!

Dave

 Smelly Fox 12 Jul 2022
In reply to AllanMac:

Yes, it’s gravitational lensing from the huge gravitational well of the galaxy cluster in the centre frame that causes the distorted and multiple refractions of the same galaxy, one that is a huge amount further from us than the galaxies in the foreground.

A truly mind blowing image. Can wait to see the rest now!

 Lhod 12 Jul 2022
In reply to Smelly Fox:

> Yes, it’s gravitational lensing from the huge gravitational well of the galaxy cluster in the centre frame that causes the distorted and multiple refractions of the same galaxy, one that is a huge amount further from us than the galaxies in the foreground.

Oh interesting, so the red warped bits are multiple distorted images of the same single galaxy? I hadn't realised that. 

 Tony Buckley 12 Jul 2022
In reply to AllanMac:

To quote from 2001, "My god!  It's full of stars".

Except in this case, the bright points of light are galaxies which in its way, is even more staggering than the science fiction of Arthur C Clarke dared suggest.  

We humans can do a bit when we put our minds to it.

T.

Post edited at 17:42
 Smelly Fox 12 Jul 2022
In reply to Lhod:

> Oh interesting, so the red warped bits are multiple distorted images of the same single galaxy? I hadn't realised that. 

I’m not certain they are all the same one, but there probably will be multiple images of the same galaxy.

 mountainbagger 12 Jul 2022
In reply to Tony Buckley:  

> We humans can do a bit when we put our minds to it.

Yeah but I think the final boss will be hard to beat and I'm kind of hoping that's the case because I don't want the game to end.

 Lhod 13 Jul 2022
In reply to AllanMac:

More info here - https://apod.nasa.gov/apod/ap220713.html

Post edited at 07:56
 Martin Hore 13 Jul 2022
In reply to AllanMac:

I've been pondering something for a while. One of the questions that I believe exercises astro-physicists is whether the universe is expanding in an ever accelerating fashion, or whether the expansion is slowing down and will eventually reverse leading to a "big crunch".  The former hypothesis currently seems to have more supporters.  My question is how can we know? The James Webb images might answer this question in relation to what was happening billions of years ago. But how can we know what's happening on a universe-wide scale today? The further reaches of the universe might already be contracting, but we couldn't possibly know as any light, or any information at all, will not reach us from those regions for billions of years. 

Genuine question this. I know we have some experts in this field on here.

Martin

 Dave Garnett 13 Jul 2022
In reply to Martin Hore:

> Genuine question this. I know we have some experts in this field on here.

Of which I am definitely not one, but yes, it does seem that the Big Crunch is now out of favour and we have the Heat Death of the Universe to look forward to.  I'm still boggled by the idea that the rate of expansion is accelerating and the implication that this is down to 'dark energy' (which isn't any kind of explanation and they might as well say it's due to black magic).

And now apparently the accepted model is that the universe is not closed, but infinite (someone mentioned this on R4 recently and was called back to confirm that this really was what she meant to say!).  Does this mean that the model I had in my head, where if you set off in any direction in what you thought was a straight line you would eventually end up back where you started (a pretty long round trip, admittedly) is now wrong? 

 elliot.baker 13 Jul 2022
In reply to Dave Garnett:

I've just finished reading Three Body trilogy (for a second time....) and the last book touches on this subject. Highly recommend!

 tlouth7 13 Jul 2022
In reply to AllanMac:

The smeared areas are indeed galaxies beyond the main cluster which are gravitationally distorted by that nearby cluster. The most distant (and so oldest) galaxies though appear as small dots (not actually point sources at the resolution of the instruments) as they are small enough in the field of view not to appear smeared.

 Robert Durran 13 Jul 2022
In reply to Dave Garnett:

> And now apparently the accepted model is that the universe is not closed, but infinite (someone mentioned this on R4 recently and was called back to confirm that this really was what she meant to say!). 

If it is infinite but of finite age starting with a big bang, presumably it has always been infinite (you can't get from finite size to infinite size in a finite time). In which case the big bang must have happened simultaneously everywhere in an infinite universe. But maybe I am missing something.

 Dave Garnett 13 Jul 2022
In reply to Robert Durran:

> If it is infinite but of finite age starting with a big bang, presumably it has always been infinite (you can't get from finite size to infinite size in a finite time). In which case the big bang must have happened simultaneously everywhere in an infinite universe. 

But I thought the whole idea of the Big Bang was that it emerged from a point, a bit like a black hole in reverse.  Although 'point' implies a specific location in space-time, which of course didn't yet exist... so, I guess it's just as accurate to say it happened everywhere at once!

 Jamie Wakeham 13 Jul 2022
In reply to Martin Hore:

I am most certainly not an expert, just an A level teacher who was a bit of a cosmologist 25 years ago... but I'll have a go.

Firstly, as lots of people have said, yes the curved parts of the images are caused by gravitational lensing.  You only get a complete Einstein ring if everything is lined up perfectly and symmetrically - it's much more common to see little sections of the ring, and that's what we're seeing here.

On the expansion: having come to the conclusion that there must have been a hot big bang (because that's by far the best explanation for redshift and the CMBR) you then ask what should happen next.  What we expected to see was a gradual slowing of expansion, as the universe does work against gravitational attraction. 

This lead to asking if the amount of attraction would ever be enough to reverse the expansion and lead to big crunch.  For a  while we got very interested in dark matter (which is absolutely nothing to do with dark energy) - this is non luminous matter which seems to hold galaxies together.  Without it they are spinning too quickly and shouldn't have been able to hold together this long.  And we wondered if the dark matter might be enough to provide the attraction needed to halt expansion and bring about big crunch.

But there seems almost no chance of this now because we're finding that the rate of expansion isn't slowing at all - as time goes by it's increasing.  Much of the evidence for this is buried in general relativity that's way beyond me these days, but there's one relatively straightforward piece of evidence.  There's a type of supernova (type 1a) which is caused by a white dwarf accreting material onto its surface and exploding when it gets to the point that the matter can undergo hydrogen fusion.  We've shown that this always happens at the same point, so all T1a supernovae are the same brightness.  That lets us use them as a standard candle - whenever we see one we can compare how bright it appears to us with how bright is really is, and figure out the distance.

But we can also measure the distance using redshift, and these two measures agree well if the supernova is relatively nearby.  At greater distances, though, the brightness comparison method tells us that they are actually further away than the redshift predicted, and that suggests the rate of expansion must be increasing.

We are not at all sure of why... dark energy has been shoehorned into the explanation to provide the push to accelerate things.

 Robert Durran 13 Jul 2022
In reply to Dave Garnett:

> But I thought the whole idea of the Big Bang was that it emerged from a point.

Yes, that is why I am puzzled by an infinite universe.

>  Although 'point' implies a specific location in space-time. 

Doesn't it just mean of zero size? Not a point within something of non-zero size.

​​​​​​

 GrahamD 13 Jul 2022
In reply to Martin Hore:

I think the idea of a "universe wide picture today" is an unhelpful concept.  Wherever you are, your "today" is unique to you.  Therefore the same time everywhere is unique to you.

 Martin Hore 13 Jul 2022
In reply to Jamie Wakeham:

Many thanks Jamie for explaining all of that. I'm still left wondering though how any of the observations you describe provide evidence for what is happening now, since we are only seeing what was happening quite a long time ago, in the case of the current Webb telescope images billions of years ago. 

Martin

 Robert Durran 13 Jul 2022
In reply to Martin Hore:

> Many thanks Jamie for explaining all of that. I'm still left wondering though how any of the observations you describe provide evidence for what is happening now, since we are only seeing what was happening quite a long time ago, in the case of the current Webb telescope images billions of years ago. 

I think it is because, although the light left the supernovae a long time ago, the redshift is due to the stretching of space since then, and therefore tells us something about what has been happening in the meantime.

 Jamie Wakeham 13 Jul 2022
In reply to Robert Durran:

As I understand things, that's right.  This is the great frustration of cosmology, of course - we can't carry out any experiments, as such, and sure as hell don't get any control group.  All we can do is look and see what's already happened, and the only way to look further back in time is to look further away... although this does allow us to compare things across billions of years just by looking at different distances.

We compare the brightness of a T1a supernova to how bright we know it must have been, and that tells us how far the light must have travelled.  But when we use redshift to work out how far away it is, the answer we get is closer.

If we try this on a relatively nearby supernova, the discrepancy is small.  If we do it on a distant one then the discrepancy is larger.  The longer ago the supernova occurred, the more the two methods don't match up.  So whilst the light has been on its way, the degree of redshift has altered.

The number of confounding problems is utterly enormous, of course.  Dust can obscure brightness so our distance measurements are quite uncertain.  T1a supernovae aren't that common, so we're not terribly confident that they are all identical (in fact we know they aren't).  It's fair to say our error bars are quite significant!

OP AllanMac 13 Jul 2022
In reply to AllanMac:

Thanks all for your replies. I knew I'd find cosmological food for thought on a rock climbing forum

I thought gravitational lensing could only be seen surrounding powerful point sources like black holes and not necessarily whole galaxies..?

If that central smudge of light in the photo is a collection of several galaxies (I'm no expert but don't think it is - it looks more like a point of light to me), could the cumulative amount of lensing be so far reaching as to distort the other reddish coloured galaxies surrounding it? Is their redness due to distance, the lensing itself, red shift, or colouration artefacts in the infra red photo separations?

Could the central smudge be a black hole or quasar more massive than we have ever seen before, hence the far reaching lensing effects into the periphery of the photo?

So many questions. My brain is frying itself.

 Jamie Wakeham 13 Jul 2022
In reply to AllanMac:

We most commonly see lensing around entire galaxies, or even galactic clusters.  The scale here is absolutely huge.  The lens in this photo is a small cluster - the white objects near the centre.

We do see lensing around individual objects like stars or black holes within the Milky Way too.

> Is their redness due to distance, the lensing itself, red shift, or colouration artefacts in the infra red photo separations?

Won't be due to artefacts - the whole thing is false colour anyway.  It was taken in the IR.  I suspect they've decided to colour further objects red.

> Could the central smudge be a black hole or quasar more massive than we have ever seen before, hence the far reaching lensing effects into the periphery of the photo?

Not a particularly big cluster, even.  The astonishing thing here is how clearly it has imaged incredibly distant objects - even from Hubble they'd just be vague blurs.

edit: decent description of what you're seeing here https://webbtelescope.org/contents/media/images/2022/035/01G7DCWB7137MYJ05C...

Post edited at 21:56
 Root1 16 Jul 2022
In reply to Robert Durran:

> Yes, that is why I am puzzled by an infinite universe.

> >  Although 'point' implies a specific location in space-time. 

> Doesn't it just mean of zero size? Not a point within something of non-zero size.

> ​​​​​​

It was infinite at the beginning. Not an easy concept to get your head around.

Clauso 16 Jul 2022
 Michael Hood 16 Jul 2022
In reply to Clauso:

Would be a slight waste of a lot of dosh if Webb wasn't significantly better than Hubble.

Clauso 16 Jul 2022
In reply to Michael Hood:

> Would be a slight waste of a lot of dosh if Webb wasn't significantly better than Hubble.

Yep... But, not my money.

 Michael Hood 17 Jul 2022
In reply to Clauso:

Think you might find your NI & taxes have already gone to ESA (pre brexit and maybe also since then) who are one of the major contributors to the Webb scope.

Clauso 17 Jul 2022
In reply to Michael Hood:

Okay, Starman... 


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