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The James Webb Space Telescope is finding too many early galaxies

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Re: The James Webb Space Telescope is finding too many early galaxies

#171

Post by pmichaud »

mikepurvis wrote: post #106
Enginerrrd wrote: post #84

Earlier quoted context omitted.

I'd say not a chance. GPT3 can regurgitate, and, in my opinion, even use knowledge, but I don't think it can synthesize knowledge.

I think it's a bit more subtle than whether it can synthesize , because clearly it can produce seemingly new work. But what it definitely cannot do is seek new abstractions . It can't be curious about an inconsistency and probe its own knowledge for possible resolutions, or design an experiment that might shed further light in an unknown area. It can't even play a board game after ingesting the rules to it, much less…

I kind of feel like _all it can do_ is seek new abstractions. It’s clustering the data into what you might think of as “concepts,” even though we haven’t made all that much progress on interrogating those concepts directly. I just think clustering concepts by their latent relationships is sort of what abstraction is.

Re: The James Webb Space Telescope is finding too many early galaxies

#172

Post by eigenket »

chrisweekly wrote: post #119
teraflop wrote: post #19

Earlier quoted context omitted.

No, we have no evidence that the universe has any kind of "edge" that is topologically different from its interior. There is a boundary to what we can see. As the early universe cooled, it changed from an opaque plasma to transparent gas. So as we look farther away, and also backward in time, we see the last point at which it was opaque; this is the cosmic microwave background. But this isn't a "real" boundary that s…

also (citation needed, this is from memory from university cosmology classes over 20y ago, maybe misremembering or info out of date) the shape of the universe may be less like a sphere and more like a toroid, or a multidimensional moebius strip. so (hand-wavy, impossible IRL but maybe illustrative / fun to think about) if you could freeze time and look far enough in one direction, you'd see the back of your own head.

There are some reasons why cosmologists don't like the idea of a universe that loops back on itself, one is that such a universe can't be both isotropic (the same in every direction) and homogeneous (the same at every point) [edit: while also being flat, as observations seem to indicate it is].

To get a rough idea of why, imagine taking a 1km by 1km square and identifying the opposite sides, you now have a homogeneous space (every point is equivalent to every other point), but it isn't isotropic because some directions are special. If you put a rock on the ground and walk due east, you'll have to walk 1km to reach the rock again (assuming you start in what used to be the center of the square it takes 500m to where the edge used to be, and another 500m from the edge back to your starting point). On the other hand if you walk south east you have to walk sqrt(2) km to get back to your rock (sqrt(2)/2 km to get to what used to be the south east corner, and another sqrt(2)/2 km to get back to where you started).

So although the torus space is homogeneous there are traces of the fact that it used to be a square, embedded in the fact that some directions are special (the 4 cardinal directions have the shortest distance to get back to where you started and the 4 intercardinal directions have the longest). Cosmologists think this lack of isotropy is essentially ugly, and don't like the idea of living in a universe where some directions are special.

Aside from just not liking the idea (which isn't very scientific) its also relevant that the universe looks pretty isotropic when do observations, we emphatically don't see traces of the sort of anisotropy you'd see in a toroidal universe anywhere.

Re: The James Webb Space Telescope is finding too many early galaxies

#173

Post by seanw444 »

KMag wrote: post #111
seanw444 wrote: post #29

Earlier quoted context omitted.

So if we can see CMB in all directions, why do we really even say "the observable universe" as though there could be more matter and more galaxies beyond what we can see? If the maximum of what we can see is implied to be before all galaxies, then shouldn't it be implied that all galaxies that exist can be seen?

Due to accelerating cosmic inflation, some galaxies are receding from us at faster than the speed of light, so their light will never reach us. The majority of galaxies (everything outside of our local cluster, IIRC) will eventually be receding faster than the speed of light and be beyond our vision forever. Yes, this means most galaxies will appear to actually pass through/into the cosmic background, from our point…

Ah, I had never thought of it that way for some reason. Duh. Thanks.

Re: The James Webb Space Telescope is finding too many early galaxies

#174

Post by dougmwne »

seanw444 wrote: post #29
Tuna-Fish wrote: post #22

Earlier quoted context omitted.

We can't see down to 0 seconds, because very soon after the big bang, the universe was filled with dense, extremely hot, opaque plasma. The closest we can get is the "recombination epoch" [0], which is roughly 370 000 years after the big bang, when, because of universal expansion, the plasma got cold enough for neutral hydrogen to start forming, at which point the universe became transparent. As protons gain electron…

So if we can see CMB in all directions, why do we really even say "the observable universe" as though there could be more matter and more galaxies beyond what we can see? If the maximum of what we can see is implied to be before all galaxies, then shouldn't it be implied that all galaxies that exist can be seen?

Here’s the important point I think you are missing. You are looking in TIME, not in space. When you look very far away, you are looking back to the beginning of time, back to a singularity where all matter and energy existed at a single point. In every “direction” you end up looking back to the same time and the same place, the beginning of everything. There’s nothing “beyond” that, it is the beginning.

If you ask, what exists today, beyond 13.7 billion light years from earth, the plausible answer is “mature galaxies like ours” but there is no possibility of collecting data or evidence of what is there, since the evidence would take more than 13.7 billion years to reach us, and in fact would never reach us because the expansion of the universe means that distances are getting larger between 2 points all the time.

Re: The James Webb Space Telescope is finding too many early galaxies

#177

Post by TeMPOraL »

moffkalast wrote: post #160
jpttsn wrote: post #126

Earlier quoted context omitted.

At that point why not call it “witchcraft;” a sciencey word for something is not an explanation.

Clearly you've never recalibrated the thermal interferometery scanner so you can reverse the polarity of the neutron flow in the isoneutronic pulse wave carrier.

That's technobabble - a pejorative term for a technical word salad that usually is an explanation, just not a very good one.

Re: The James Webb Space Telescope is finding too many early galaxies

#178

Post by pndy »

starik36 wrote: post #42

Does this mean that big bang either didn't happen or happened in a different way that we think of it? Or happened far earlier than we think it did? Complete layman here.

I'm not an expert but from what I understand, scientists observed the very distant galaxies which shouldn't be visible according to most popular model of the universe evolution. And if these observations will be confirmed then we might get more accurate model which totally differs of the most popular one the scientists agrees upon.

Far distant young galaxies should be seen as "red", but these aren't and that's the issue here - JWST captured these very bright. It's possible that the universe evolves in a different way and Hubble's law doesn't applies

https://en.wikipedia.org/wiki/Hubble%27s_law

Re: The James Webb Space Telescope is finding too many early galaxies

#179

Post by CuriouslyC »

cwkoss wrote: post #14

Is it possible that the 'edge' of universe reflects light? Have scientists been able to conclusively rule that out somehow? Does the universe even have an edge? What is our current understanding of what the boundaries of the universe might be like?

Talking about the edge of the universe implies space is a thing. Physics works just fine if you imagine the x, y and z of particles describes an arbitrary set of coupled attributes on the particle itself. It is more likely that space is an emergent property of the entanglement between information, and in that case the idea of a boundary is nonsensical. Under that model, "spacetime" would behave like a foam - if one bit of it pulled far enough away from the rest it'd shoot off as a bubble.
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