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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

#111

Post by KMag »

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?

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 of view.

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

#112

Post by chrisweekly »

micromacrofoot wrote: post #49
oblio wrote: post #26

Earlier quoted context omitted.

I was thinking about something weird right now. We don't (can't?) even know if there weren't multiple Big Bangs, right? I.e we're just in a specific "universe" we can observe, but maybe several of these are just side by side, not necessarily parallel as in parallel realities.

assuming light from a big bang travels in all directions, then another big bang's light could be heading in our direction and potentially observable — the reason we can't observe the entirety of our universe is that spacetime is expanding in a way where light at the beginning isn't traveling fast enough to outpace expansion

wait, no, a big bang doesn't happen IN spacetime, it IS spacetime per se. that's part of what makes it so confusing.

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

#113

Post by Eduard »

sebzim4500 wrote: post #98
college_physics wrote: post #59

I don't know if this instance qualifies as one, but I think its fair to say that cosmology is the one domain of "fundamental" physics where "discrepancies" or question marks keep piling up and not really resolving. It the pattern of previous science revolutions repeats, there could come a point where reinterpreting the large existing body of knowledge using a different paradigm would explain an number of "oddities" i…

I think this says less about cosmology and more about the incredibly effectiveness of the standard model in the regime we can test directly on earth. If we compare ΛCDM to most other scientific theories it doesn't look so bad in terms of discrepancies. Certainly there are many unexplained effects in solid state physics, there isn't even an accepted explanation for why rubbing a balloon on your head makes it stick to…

> there isn't even an accepted explanation for why rubbing a balloon on your head makes it stick to a wall

But the accepted explanation is "static electricity", no?

Or do you mean we don't "really" know when asking a couple of follow-up "why?" questions further?

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

#114

Post by dave333 »

Beltalowda wrote: post #48
dave333 wrote: post #7

[flagged]

That entire site reads like "what if Elizabeth Holmes set up a power generation company?" Reading up on the company on Wikipedia, it seems to be pretty much exactly that. https://en.wikipedia.org/wiki/Brilliant_Light_Power

Read the talk page too - there's been a lot of dispute about that page

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

#115

Post by downrightmike »

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.

We have lots of theories, but we'll never be certain as we will never see back to the BB. Everything was hot plasma for 370k years after the BB. We can get maybe that close, but no further. We are still exploding anyways.

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

#116

Post by lostmsu »

ben_w wrote: post #21
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?

The far limit of the visible universe is the cosmic microwave background, which is the heavily red-shifted view of when all of space was filled with an opaque plasma of similar temperature to the surface of a star[0]. The galaxies we're seeing are in front of that. [0] 3000 K, https://en.wikipedia.org/wiki/Recombination_(cosmology)

This is hard to internalize. Why do we continue seeing CMB? My understanding is that the early galaxies still produced light after recombination.

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

#118

Post by teawrecks »

jackmott42 wrote: post #105
college_physics wrote: post #59

I don't know if this instance qualifies as one, but I think its fair to say that cosmology is the one domain of "fundamental" physics where "discrepancies" or question marks keep piling up and not really resolving. It the pattern of previous science revolutions repeats, there could come a point where reinterpreting the large existing body of knowledge using a different paradigm would explain an number of "oddities" i…

I don't think it is fair to characterize cosmology as not making progress no. Stuff is far away and occluded and hard to measure and see. Each improvement in observation causes a need to refine previous ideas, as expected. There are of course the two big mysteries that have lingered for a long time: Dark Matter and Dark Energy, but other areas of physics have lingering mysteries as well.

I almost had the same reaction, but technically they didn't say anything about cosmology not making progress. It's entirely reasonable to assume a scientifically minded person describing a field as "piling up question marks" means they think it's making a LOT of progress. Imagine a field that answers questions more often than it finds new ones; that'd be a pretty stagnant field to be in.

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

#119

Post by chrisweekly »

teraflop wrote: post #19
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?

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.

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

#120

Post by dinkumthinkum »

RosanaAnaDana wrote: post #97
purpleblue wrote: post #87

Earlier quoted context omitted.

If you give GPT3 code with a bug in it, and ask it to find the bug, it can't really do that. I'm pretty sure giving it all the data and asking it why things aren't working the way it should, it wouldn't have actual knowledge. There's a depth to explaining things that GPT still can't do. It's still astonishing, and has completely changed my idea on what AI can do, like write plays with very incredible context (better…

>If you give GPT3 code with a bug in it, and ask it to find the bug, it can't really do that. The hell are you talking about? I've been doing this literally any time I need something fixed and it does just fine.

It doesn’t solve non-trivial bugs. It can bugs that match patterns that have been asked a lot if Stackoverflow or something like that.
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