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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

#391

Post by deadbeeves »

Balgair wrote: post #367
deadbeeves wrote: post #345

Earlier quoted context omitted.

Because the primordial universe was in a state of extremely fast expansion, while black holes today exist in space-time that is almost exactly flat. In fact, if the universe really started from a singularity, the expansion was infinitely fast for an instant.

To hedge the next question then: Why was the universe expanding so quickly? It seems that the expansion must have been so fast that it was going faster than light speed, right? Otherwise the very dense universe must have gone black-hole.

The expansion of space itself is not comparable to the speed of light, but yes, I would say it's probable that it would have caused particles (or whatever there was at that time) to spread out faster than light, thus disconnecting them causally and preventing gravitational interaction. As for the why, answering that would involve answering why the Big Bang happened, which given our current understanding would veer into metaphysics. As far as we can tell, it's just what the universe does.

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

#392

Post by craftsman »

eru wrote: post #384
craftsman wrote: post #380

Earlier quoted context omitted.

I understood their point to be that that based on our understanding of basic physics and chemistry, the energy balance is such that the Earth system is gaining energy, and that this will lead to increased temperatures among other things. Certainly there are all kinds of complexities about how that energy will be distributed and what the effects will be, but just in terms of a simple energy balance model based on well…

> Certainly there are all kinds of complexities about how that energy will be distributed and what the effects will be, but just in terms of a simple energy balance model based on well understood physics, it would be difficult to make the case that warming won't happen. There are lots more effects. When lots of volcanoes erupt, we also see more CO2, but we see the climate cool down. That's because the effect of the C…

Not in the long run. If CO2 levels are increasing and the energy balance into the Earth system is positive, then the basic physics that the original poster referred to will result in warming. The net energy increase of the system will result in a higher equilibrium temperature.

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

#393

Post by SkyMarshal »

Rury wrote: post #387
SkyMarshal wrote: post #30

Earlier quoted context omitted.

> 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…

I'm still not convinced that the expansion of the universe is accelerating based on current evidence. That argument largely comes from supernovae appearing dimmer than we think they should, and more distant things appear more red and it looks that way in any direction we look. But the thing is, we sometimes calculate how distant things are based on redness, so it's kind of circular reasoning. Sure we have other thing…

Considering the two methods for measuring the rate of the universe’s expansion differ by about 10%, the question seems unsettled at best. You’re not wrong to question it.

https://youtu.be/hps-HfpL1vc

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

#394

Post by bpye »

Taniwha wrote: post #291
AstixAndBelix wrote: post #250

Earlier quoted context omitted.

Computer Science doesn’t get the pass, unfortunately. First of all because it’s a branch of maths, so in reality it doesn’t have any instruments to worry about. Secondly, applied CS relies on an incredibly simple instrument: binary logic gates. The computers we have today are just a mesh of stuff that flips on and off with no intermediate states. That’s pretty primitive as a means of expression and computation compar…

Oh, let me introduce you to metastability ....

Is that computer science or is that physics though?

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

#395

Post by NavinF »

TillE wrote: post #306
sebzim4500 wrote: post #98

Earlier quoted context omitted.

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…

My favorite poorly understood phenomenon in basic physics is the Mpemba effect, where hot water can freeze faster than cold water under certain circumstances. It's just phase changes of water in a simple experiment you can do at home, and I think there's still no widely accepted explanation.

That's because nobody's replicated that effect in a real lab. People who claimed to observe effect didn't even bother to bypass the freezer thermostat and force the compressor to stay on, nor did they measure power consumption. It's just shoddy science.

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

#396

Post by mansoon »

WXLCKNO wrote: post #286
Spkeat wrote: post #278

This can further reinforce the idea that the unobservable universe was always there and that the big bang is only a pattern of movement of the cluster of galaxies and it is only the information that has managed to arrive from our position.I want to see how big bang theory falls into an optical illusion.

I don't know which idea is harder for me to conceptualize. That something has always existed or that it came to exist out of nowhere-ish.

Once you factor time out of your pre-universal reality, these are compatible.

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

#397

Post by jadbox »

satvikpendem wrote: post #323
dark-star wrote: post #208

Earlier quoted context omitted.

My favorite theory is that the universe is finite, some sort of (hyper)sphere or -torus. If we could just look far enough out there we would see our own galaxy What would be even cooler is if it was warped like a moebius strip in a higher dimension, so that when we look out there, everything is mirrored from "our" reality :-D

You should read the short story The Tower of Babylon by Ted Chiang who also wrote Stories of Your Life , the inspiration for the movie Arrival .

That was one of my favorite stories and certainly relevant to the theories here.

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

#398

Post by bpye »

soiler wrote: post #13
cevn wrote: post #4

Can someone explain to me what would be behind the galaxies if we could see it, to the point of 0 seconds after the big bang? Black, white, is it even possible?

We can actually already see that time period, in its present form. It's called the Cosmic Microwave Background. It is the (now extremely cold) energy which permeated the entire universe in that very early time period. The entire universe was opaque and extremely hot... then as it expanded, it began to cool enough for particles and then atoms to form. Only then were stars possible, and later galaxies. How/why can we s…

> and it came down very early in time.

Is this just because we’ve used it to define the start?

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

#399

Post by cdogl »

jquery wrote: post #377
idlewords wrote: post #325

This was predicted by astronomer Stacy McGaugh on his super interesting blog as a natural consequence of modified Newtonian dynamics ( https://tritonstation.com/2022/01/03/what-jwst-will-see/ ). McGaugh came to support MOND over dark matter reluctantly for just such reasons—MOND routinely predicts things in advance that dark matter struggles to justify ex post facto, usually by adding additional moving parts to the m…

It seems to me, as a layperson, if MOND was hypothesized first, it would be the dominant theory. It’s so elegant and simple with so much explanatory power. However, because it was hypothesized much later, the fact it matches past predictions is given no weight, despite its simplicity. I think this is a bit of a mistake. I believe that simplicity itself is evidence. Dark matter theory is starting to feel like the epic…

I am too ignorant to weigh in on MOND vs dark matter, but this seems entirely possible.

In all domains - not only physics - there are many possible models that seem to match our observations. They’re continually adapted over time in order to meet to perceived needs and reality (see: the medieval European church).

Paradigm shifts can happen incremental or explosively. With the enormous sunk cost in our existing models - not least the millions of people educated in them - incremental change becomes harder. If MOND or any alternative theory is “true”, it faces a distinct challenge: there are decades of experiments and observations that have been fit to our existing model. To take over, it needs to answer _all_ of it - or provide so much utility that the incentives shift.

Success can be paralysing. In tech, a new idea can come along and shake everything up by showing results and solving a problem. The only way a new model of physics can do that is by generating a practical breakthrough. I hope I’m wrong!

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

#400

Post by throwawaymaths »

nickelpro wrote: post #383
jquery wrote: post #377

Earlier quoted context omitted.

It seems to me, as a layperson, if MOND was hypothesized first, it would be the dominant theory. It’s so elegant and simple with so much explanatory power. However, because it was hypothesized much later, the fact it matches past predictions is given no weight, despite its simplicity. I think this is a bit of a mistake. I believe that simplicity itself is evidence. Dark matter theory is starting to feel like the epic…

If MOND completely described observable phenomenon it would supplant dark matter, but it doesn't. MOND still requires dark matter, just less of it. Or, to quote Milgrom, "some standard matter in some form that has not been detected"[1]. Which, IMHO, is nearly isomorphic to DM as far as statements go. So until we figure out what the missing mass is, MOND is widely viewed as an unnecessary complication. There is missin…

The explanatory power of dark matter is so weak though. With the right clumping of LCDM you could probably also explain various reports of poltergeists around the world.

Then you could claim that reports of poltergeists are evidence of LCDM over MOND because it's another phenomenon that MOND can't explain.

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