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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

#191

Post by Jeff_Brown »

lp4vn wrote: post #185
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…

What I'm going to ask you is completely dumb, but keep in mind I don't know much of physics. If my understanding is correct, when mass gets dense enough inside, a star you have a black hole, that would be like a hole in the fabric of space time. Ok, we have black holes in the contemporary universe. So how was the primordial universe a ball of dense, extremely hot, opaque plasma without becoming a huge black hole?

+1! Infinite density => way blacker than a black hole, no?

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

#192

Post by suetoniusp91 »

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…

The simulation gets less cohesive the farther from earth you look.

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

#193

Post by bee_rider »

reptation wrote: post #110
Maursault wrote: post #76

Earlier quoted context omitted.

> The universe is 13.7b yo, but due to acceleration of expansion, if you could "teleport", it's actually currently 93b ly across. So we're already in a bubble within a greater universe that we'll never be able to escape This number, the age of the universe, has changed a few times since I learned to read 45 some years ago. What are the chances that this isn't really "the" universe, but what we know as the observable…

It's worth pointing out that there is a minority of physicists who don't accept the Big Bang as proven beyond doubt. An alternative theory would be a 'steady-state' universe which, as you suggest, would be much older than the ~14 BYO age. If the medium of space itself dispersed light for instance, red shifts might be observed that explain the astronomical data.

Just for any future historians: all us normal people are aware that the idea of the Big Bang seems a little fantastical, but relativity or whatever is, like, way complicated. Most of us just have to trust the physicists. Of course now that you have the Theory of Everything, notation and thought-experiments developed to make it obvious, and relativity is just a special case, we look pretty dumb. But if you look at the operators that your undergrads pull out to solve Theory of Everything equations and try to somehow derive them with ancient 21’st century math, they are actually really complicated!

Actually, having a bit of sympathy now for the folks who believed in the Luminiferous aether.

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

#194

Post by Jeff_Brown »

dougmwne wrote: post #174
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?

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, w…

Is it true that space had no volume at the Big Bang? I understand that density rises without (known?) bound as we approach the Big Bang, but even if you compress infinite space by an infinite factor you might still have infinite space -- infinity divided by infinity is undefined.

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

#195

Post by marricks »

TheOtherHobbes wrote: post #151

I'm going to be very amused if the Steady State Model - an unpopular relic from the 1940s - turns out to be correct. https://en.wikipedia.org/wiki/Steady-state_model

There’s also more spiral galaxies than expected!

If steady state gained favor that would be super fun, but this quote from the article seems to throw a little cold water on that.

> At the same time, she notes that yesterday’s disks are different than modern ones. “They’re not today's Milky Way,” she notes. “They're turbulent, they're messy, and we need to study them more.”

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

#196

Post by foxyv »

gwd wrote: post #143
foxyv wrote: post #128

Earlier quoted context omitted.

> there isn't even an accepted explanation for why rubbing a balloon on your head makes it stick to a wall You mean dielectric moments and static electricity? Electromagnetism is the one thing we know the most about. It's that spooky gravity junk that makes us scratch our heads. It never seems to behave quite right and doesn't mesh with all the other forces.

> You mean dielectric moments and static electricity? You're confusing what with why . My understanding is that everyone knows it has something to do with electrons collecting on the balloon; but nobody quite knows why rubbing rubber against hair causes the electrons to do that.

I think I got confused because I was thinking about why it stuck to the wall, rather than why it accumulated charge. I know why electrically charged objects stick to things. The why of how they got like that is a bit different as you mentioned. Triboelectric effect is spooky, but there are some theories. It's one of those non-linear messy quantum things that's a pain in the neck to solve.

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

#197

Post by Jeff_Brown »

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…

I thought the logic of inflation had no limit, and eventually, everywhere, even atoms themselves would come apart.

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

#198

Post by vl »

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…

>Certainly there are many unexplained effects in solid state physics

Wait for it… Why ice is slippery?

Usual explanation is completely incorrect. Actual semi-conclusive research just recently happened.

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

#199

Post by vaidhy »

jpttsn wrote: post #126
Eduard wrote: post #113

Earlier quoted context omitted.

> 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?

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

We do not call it witchcraft, because that is the end of the discussion and the answer. We call it unknown because it is knowable and is the beginning of the experiments.

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

#200

Post by colordrops »

eganist wrote: post #15
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?

> Is it possible that the 'edge' of universe reflects light? Have scientists been able to conclusively rule that out somehow? It's not an edge the way you think. It's the edge of what we can see based on the known age of the universe and how much light has reached us. I.e no real boundaries as best as we can tell. The best way you can look at this is that early galaxies are being found earlier than expected based on…

How does this work with the big bang happening at a specific point in the past?
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