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The James Webb Space Telescope is finding too many early galaxies

skyandtelescope.org

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

#411

Post by kgwgk »

paulrouget wrote: post #262
xenadu02 wrote: post #213

Earlier quoted context omitted.

The strong nuclear force, electromagnetic force, and even gravity are strong enough to overwhelm the expansion within individual galaxies and even local groups of galaxies. In other words the expansion of spacetime very very very slightly tries to shift the atoms of your body apart but we can't even detect it because ordinary forces like chemical (electromagnetic) bonds are exponentially stronger - enough to pull thi…

I don't think that's true. Expansion is not very weak around matter, it just doesn't exist. It sounds a little counter intuitive to think that expansion "shutdowns" as we get closer to galaxy. But that's because expansion and gravity are a little more complicated that just a force. We over simplify what expansion really is, which leads to this type of thinking. Expansion and gravity are results of the same equations.…

> Einstein equations are difficult to use, so we usually split the results in two models, FLRW (empty space) and Schwarzschild metrics (around matter). Computing the equations leads, respectively, to expansion and gravity. And it's not like there's one and the other, with gravity fighting expansion. It's "one or the other".

Arguably splitting a complex model of reality in two for convenience and saying that it’s “one or the other” is also an over simplification.

By the way, the same wikipedia entry also says things like “gravity binds matter together strongly enough that metric expansion cannot be observed on a smaller scale at this time.”

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

#413

Post by yipbub »

xyzal wrote: post #410

Articles like these make me want to stop doing everything and isolate in the basement for several months to study physics. Then I realize I have a family to feed and elderly parents to take care for. Sigh, so many beautiful mysteries in the world, and only one life. edit: A friend told me germans have the word "Sehnsucht" to describe such a feeling. So I guess it might be somewhat universal.

Same, but I imagine doing it in a country house with a table looking out into a lovely garden, and a mountain path nearby for long walks thinking about things.

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

#414

Post by ankit219 »

xyzal wrote: post #410

Articles like these make me want to stop doing everything and isolate in the basement for several months to study physics. Then I realize I have a family to feed and elderly parents to take care for. Sigh, so many beautiful mysteries in the world, and only one life. edit: A friend told me germans have the word "Sehnsucht" to describe such a feeling. So I guess it might be somewhat universal.

I have kind of done that for last few months. Chat GPT helped immensely with that. I recently even asked if it's worth it to go back to academia. Still exploring that.

A few things that I recently understood or read about.

- Fermi Paradox - with help of chatgpt https://imgur.com/a/LuVV6iK

- How the age of universe was calculated.

- Redshift

- How age of solar system was calculated. I previously thought just like the universe is expanding, so is solar system. Turns out that is not the case. The distances have been more or less fixed. (i thought sun would be losing some mass, weakening gravitation for that to happen, nothing like that).

- Exo-planets.

- a lot of nuclear physics.

- Parallel universe theory according to quantum mechanics.

- gravitational waves (how to measure ripples in spacetime https://www.wired.co.uk/article/catching-cosmic-rays-virgo-i...)

- Theories around nuclear fusion and how ML, High Temp super conductivity and more precise chips are making advances possible.

And so on.

Will add one special mention to this: https://www.quantamagazine.org/why-this-universe-new-calcula... (this universe exists because it has the highest entropy is a layman summary of the article)

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

#415

Post by [deleted] »

ankit219 wrote: post #414
xyzal wrote: post #410

Articles like these make me want to stop doing everything and isolate in the basement for several months to study physics. Then I realize I have a family to feed and elderly parents to take care for. Sigh, so many beautiful mysteries in the world, and only one life. edit: A friend told me germans have the word "Sehnsucht" to describe such a feeling. So I guess it might be somewhat universal.

I have kind of done that for last few months. Chat GPT helped immensely with that. I recently even asked if it's worth it to go back to academia. Still exploring that. A few things that I recently understood or read about. - Fermi Paradox - with help of chatgpt https://imgur.com/a/LuVV6iK - How the age of universe was calculated. - Redshift - How age of solar system was calculated. I previously thought just like the…

[deleted]

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

#416

Post by habibur »

ash wrote: post #409
cryptonector wrote: post #408

Earlier quoted context omitted.

> If there is another reason the light from distant galaxies turn to red, kind of a long-distance light fatigue, we couldn't really know. It's not just red shift that demands an explanation, but also that the sky (space) is dark. If space wasn't expanding then the skies would be bright white. Another thing is the second law of thermodynamics, which very strongly implies a lot of standard cosmology. Of course, standar…

Why would it be bright white?

Any straight line you draw from earth to any direction in the sky will then reach a star.

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

#417

Post by bombolo »

AstixAndBelix wrote: post #250
User23 wrote: post #155

Earlier quoted context omitted.

There's a joke that calling Computer Science Computer Science is like calling Astronomy Telescope Science, but part of what makes it funny is the ring of truth to it. Our instruments really do limit our observations. The advantage Computer Scientists have is that we can glimpse a world of Platonic Forms[1], where Functions, and Sets, and Information exist, or something close enough for government work, merely through…

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…

> The computers we have today are just a mesh of stuff that flips on and off with no intermediate states.

Only when things are working properly and there isn't too much cosmic radiation, interference, strange patterns accessing memory, someone turning on a light…

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

#419

Post by Cthulhu_ »

yipbub wrote: post #413
xyzal wrote: post #410

Articles like these make me want to stop doing everything and isolate in the basement for several months to study physics. Then I realize I have a family to feed and elderly parents to take care for. Sigh, so many beautiful mysteries in the world, and only one life. edit: A friend told me germans have the word "Sehnsucht" to describe such a feeling. So I guess it might be somewhat universal.

Same, but I imagine doing it in a country house with a table looking out into a lovely garden, and a mountain path nearby for long walks thinking about things.

I'm sure there's a catchy phrase for that kind of thing, intellectual cottagecore maybe?

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

#420

Post by Cthulhu_ »

TillE wrote: post #311
abtinf wrote: post #211

Earlier quoted context omitted.

If “it all keeps changing”, which thwarts their attempts to “model an insanely complex system”, then wouldn’t that mean any claim about “global warming” is actually a claim to possessing a priori knowledge?

We know very well how carbon dioxide interacts with infrared radiation (easily tested with an IR spectrometer), and we know human activity releases enormous quantities of carbon dioxide into the atmosphere, which does not magically disappear. Precise predictions are hard, but the general direction of travel cannot be seriously disputed without arguing against the above simple facts.

> Precise predictions are hard, but the general direction of travel cannot be seriously disputed without arguing against the above simple facts.

To add, the predictions re: global warming seem to have been too optimistic, and they were already gloom and doomsaying enough decades ago. I scoffed when I read a headline saying something about a specific glacier being gone in 100 years - I'm sure it'll be much sooner than that.

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