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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

#31

Post by varjag »

JetSetWilly wrote: post #6
throwawaymaths wrote: post #5

Worth noting: For a very long time MOND has been predicting earlier galaxies than LCDM.

This is not unusual. There's many predictions made by MOND ahead of the fact that are borne out by reality. But don't worry - dark matter will be "retrofitted" so that it fits the facts and everybody will suffer collective memory loss again. Edit: see for example table 1 on page 12 here: https://arxiv.org/pdf/2110.06936.pdf from a review of prior expectations by both MOND and dark matter vs how they turned out agains…

But MOND itself is a "retrofit" to make it agree with the data, isn't it? It's in the name.

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

#32

Post by rcme »

varjag wrote: post #31
JetSetWilly wrote: post #6

Earlier quoted context omitted.

This is not unusual. There's many predictions made by MOND ahead of the fact that are borne out by reality. But don't worry - dark matter will be "retrofitted" so that it fits the facts and everybody will suffer collective memory loss again. Edit: see for example table 1 on page 12 here: https://arxiv.org/pdf/2110.06936.pdf from a review of prior expectations by both MOND and dark matter vs how they turned out agains…

But MOND itself is a "retrofit" to make it agree with the data, isn't it? It's in the name.

Every theory is a retrofit. A useful theory is also predictive.

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

#33

Post by [deleted] »

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…

[deleted]

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

#34

Post by make3 »

pwatsonwailes wrote: post #18
eganist wrote: post #15

Earlier quoted context omitted.

> 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…

Without getting into lots of detail, this is basically correct. It's why we talk about the observable universe. There's lots of stuff we can't see because the light from it won't reach us.

how can that work if nothing is faster than light in the referential of the objects being compared? is it that space expands faster than light moves?

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

#35

Post by [deleted] »

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?

[deleted]

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

#36

Post by boppo1 »

SkyMarshal wrote: post #30
pwatsonwailes wrote: post #18

Earlier quoted context omitted.

Without getting into lots of detail, this is basically correct. It's why we talk about the observable universe. There's lots of stuff we can't see because the light from it won't reach us.

> because the light from it won't reach us. This is one of the most interesting aspects to the universe. It's not, "because the light from it hasn't reached us yet but is on the way and will get here eventually." Rather it's that the rate of expansion of the universe is accelerating, so that we're moving away from parts of it faster than its light can cover the distance to us. It will never reach us. That's mindboggl…

What do I have to study to understand all this in mathematical terms? Is an undergrad text good enough?

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

#37

Post by sebzim4500 »

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?

No, because galaxies almost certainly exist which are further than the CMB. It's just that the light travelling from them has not been able to reach us in the time since it was emitted.

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

#38

Post by seanw444 »

make3 wrote: post #34
pwatsonwailes wrote: post #18

Earlier quoted context omitted.

Without getting into lots of detail, this is basically correct. It's why we talk about the observable universe. There's lots of stuff we can't see because the light from it won't reach us.

how can that work if nothing is faster than light in the referential of the objects being compared? is it that space expands faster than light moves?

Correct, as I understand it. No matter can travel at the speed of light, and no light can travel faster than the speed of light. But the rule doesn't extend to the rate of expansion of the "field" on which those things exist.

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

#40

Post by dwaltrip »

sebzim4500 wrote: post #37
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?

No, because galaxies almost certainly exist which are further than the CMB. It's just that the light travelling from them has not been able to reach us in the time since it was emitted.

And never will reach us, as the space in between us and that distant light is expanding to quickly.
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