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Astrophysicists Puzzle over Webb’s New Universe

quantamagazine.org

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Re: Astrophysicists Puzzle over Webb’s New Universe

#11

Post by ben_w »

jdw64 wrote: post #2

As observations become too numerous, it seems like it can be summarized as there now being too many possible candidate explanations. As data increases and becomes clearer, more and more things don't fit the existing theories. What are the current theories explaining the early universe? What happened to the Big Bang? I only studied astronomy up to an undergraduate level, so I don't really know. I imagine that various…

With the caveat I'm summarising from what PBS Space Time and Dr Becky* say:

• Big Bang: we can only see back to surface of last scattering, i.e. the CMB, extrapolating backwards goes "???" at much the same point as it did a few decades back because we still have not unified quantum mechanics and general relativity

• CMB should only have isotope distribution of Big Bang nucleosynthesis, that hasn't changed in the last decades, dunno if that's what you meant by "various non-uniform gases were scattered around"?

• Variations in density of CMB do exist, key phrase is "Baryon acoustic oscillations", while they're very small magnitude they're also massive in distance scale, so they're how galactic clusters formed (that scale rather than stars directly): https://en.wikipedia.org/wiki/Baryon_acoustic_oscillations

https://www.youtube.com/watch?v=PPpUxoeooZk

https://www.youtube.com/watch?v=LRUTnoveZs8

• Re: "Perhaps the expansion of space wasn't uniform either": I heard about specifically "Timescape Cosmology", but a quick search says that's part of a broader category of inhomogeneous cosmologies: https://en.wikipedia.org/wiki/Inhomogeneous_cosmology#Timesc...

https://www.youtube.com/watch?v=SXg6YVcdOcA

https://www.youtube.com/watch?v=JlNVZz5D6WE

• Re: "and when space expands or contracts, energy is generated": no, general relativity does not in general conserve energy, and it is related to the curvature of spacetime. Simple example is that the photons in the CMB have much less energy to us than they did to the atoms they were emitted from**: https://www.youtube.com/watch?v=04ERSb06dOg

* I assuming I'm correctly judging the level and attention to detail they're providing, given the detail they put in and references to specific research publications. My degree is Software Engineering.

** There's also a Veritasium video about this, but to me Veritasium feels like a BBC 2 evening popular science show, so I'm not as confident about recommending it.

Re: Astrophysicists Puzzle over Webb’s New Universe

#14

Post by jdw64 »

ben_w wrote: post #11
jdw64 wrote: post #2

As observations become too numerous, it seems like it can be summarized as there now being too many possible candidate explanations. As data increases and becomes clearer, more and more things don't fit the existing theories. What are the current theories explaining the early universe? What happened to the Big Bang? I only studied astronomy up to an undergraduate level, so I don't really know. I imagine that various…

With the caveat I'm summarising from what PBS Space Time and Dr Becky* say: • Big Bang: we can only see back to surface of last scattering, i.e. the CMB, extrapolating backwards goes "???" at much the same point as it did a few decades back because we still have not unified quantum mechanics and general relativity • CMB should only have isotope distribution of Big Bang nucleosynthesis, that hasn't changed in the last…

thanks!!

Re: Astrophysicists Puzzle over Webb’s New Universe

#15

Post by 6thbit »

That’s a beautiful article showcasing our predicament in having access to more information about the universe. Now i have to be the one to ask the dumb defensive question:

what makes us so certain that we can trust what we see on James Webb? Can we definitely discard a measurement problem?

Re: Astrophysicists Puzzle over Webb’s New Universe

#16

Post by juanani »

sdoering wrote: post #9
qsera wrote: post #7

Earlier quoted context omitted.

[flagged]

WTF. We have such great medical advancement in cancer treatments, vaccines, reconstructive surgery h just to name a few. Not sure what you are referring to, but the only unjustifiable things in the (so called) medical field are snake oil sales men trying to make a quick buck by instilling a fear of science into people's minds. Like anti-vax idiots. Or homeopathic bullshit.

[dead]

Re: Astrophysicists Puzzle over Webb’s New Universe

#17

Post by tigerlily »

tigerlily wrote: post #10
jdw64 wrote: post #2

As observations become too numerous, it seems like it can be summarized as there now being too many possible candidate explanations. As data increases and becomes clearer, more and more things don't fit the existing theories. What are the current theories explaining the early universe? What happened to the Big Bang? I only studied astronomy up to an undergraduate level, so I don't really know. I imagine that various…

I took a good long look at the CMB picture, including the caption. It basically says the Universe was one big hot apparently uniform ball at one stage. I don't know what conditions were like before that stage, but like Eric Idle says, nothing can come from nothing. Dark energy is a horse shit name for a theory that was horse shit to begin with. The Universe is probably just inhomogeneous, like your intuition is sayin…

I will say that the current and future telescope lineup is amazing and is bound to reveal: even more fascinating insights and mysteries!

Re: Astrophysicists Puzzle over Webb’s New Universe

#18

Post by Tanath »

phyzix5761 wrote: post #8

> Faced with observations of early black holes and galaxies that weren’t expected to exist, scientists have come up with a wealth of new theories to explain them. Now they just need to figure out which ones are true. This subtitle really bothers me. Science isn't about finding out what is true. Science is about finding out what is false and building models to explain the rest. We can never confidently say we know som…

Hypotheses are made for a reason though. Science is still about finding what's true, and ruling out what's not is part of the process/method for doing so. Sometimes all the alternatives to the truth are ruled out and we know the truth. Scientific revolutions happen sometimes, but they still need to explain everything the old theories explained. The newer theories may still be wrong, but in different and hopefully fewer ways. It's important to keep the scope of what's been demonstrated/tested in mind to not be misled about what truths have been established. Newton's physics is still largely true within the scope of everyday experience, for example.

Re: Astrophysicists Puzzle over Webb’s New Universe

#20

Post by neffy »

6thbit wrote: post #15

That’s a beautiful article showcasing our predicament in having access to more information about the universe. Now i have to be the one to ask the dumb defensive question: what makes us so certain that we can trust what we see on James Webb? Can we definitely discard a measurement problem?

Some of the Hubble results were also raising questions. At the same time, I read one of the papers on the galaxy stuff, and what struck me was they were identifying galaxy shapes by counting the pixels each galaxy had, so there are definitely some question marks over how they do some of this.
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