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Webb and Hubble confirm Universe's expansion rate

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Re: Webb and Hubble confirm Universe's expansion rate

#191

Post by qup »

pishpash wrote: post #60
rf15 wrote: post #53

Earlier quoted context omitted.

This, together with the endless philosophising around dark energy, dark matter and whatnot paints a pretty strong arrow towards our models having some flaws when it comes to their large-scale application. I hope to live long enough to see where we made our mistake and get a better model.

Almost every model we build of more trivial things based on observation always turns out to be not really right. I cannot imagine why one of the universe that has had multiple version updates in the last 100 years to not also be grossly mistaken. I also don't expect the full model to be simple or beautiful. We may be thinking wishfully based on massive extrapolation and cutting corners to suit our narrow view into th…

It's probably spaghetti code

Re: Webb and Hubble confirm Universe's expansion rate

#192

Post by physicles »

rexer wrote: post #183
physicles wrote: post #169

The article mentions the cosmic distance ladder, which is one of my favorite things in all of science. How do we know how far away the really far stuff is? It's non-trivial and I find the history fascinating. It all started with knowing the distance from the earth to the sun. Nobody had a clue until Richer and Cassini got within 10% in 1672. Then we nailed it down in 1769 with James Cook's voyage to Tahiti, the prima…

Great comment! Maybe you can help me with a book recommendation? I was recently looking for a book which was basically your comment, but more in depth and covered the last couple thousand years. I wanted a to read about the history of astronomy - yknow, what was the state of the art in, say, 1350 or whatever. If you know of anything, I’d be super interested!

Unfortunately I don't have any books to recommend. I don't remember where I learned about Cepheid variables and type 1a supernovae (maybe science shows, maybe youtube, ...) but I learned about the transit of Venus stuff on a big Wikipedia rabbit hole one evening.

I think the pre-quantum mechanics era for physics and astronomy is super interesting. People figured out so much with such primitive tools, and it's all very accessible and easy to understand.

Re: Webb and Hubble confirm Universe's expansion rate

#193

Post by pigpang »

harywilke wrote: post #42

Dr.Becky goes over this in a video [0] from a year ago about the divergent results obtained by the two main ways we measure the rate of expansion. Cosmic Microwave Background Vs. Supernovae. As the accuracy of each method has improved, the end results have diverged. [0] 'theJWST just made the "Crisis in Cosmology" WORSE' https://www.youtube.com/watch?v=hps-HfpL1vc&t=858s

Unfortunatelly, title of article on HN contradicts content of article, so many HN readers skip article because of "confirmed" (in other words: nothing new).

IMHO, a Tired Light theory will better explain facts, but it will require paradigm shift, so there will be a lot of resistance before revolution.

Re: Webb and Hubble confirm Universe's expansion rate

#194

Post by orlp »

theoreticalmal wrote: post #141
throwawaymaths wrote: post #85

Earlier quoted context omitted.

There's a 'fringe' theory that the CMB is not the echo of the big bang but rather the redshifted black body radiation of intergalactic dust (apparently the numbers are about right). Although the primary proponent of this theory is trying to justify some sort of cyclic universe model with it, if my understanding is correct it would still be compatible with a 'standard' big bang that has the "longer" (aka galactic expa…

I can’t believe it. First they take Pluto from us, next they’re going to tell me the static on my tv set isn’t the remnants of the Big Bang, but just hot dust? My childhood is crumbling!

Your comment made me realize how some younger people have no idea of, or at least no first-hand experience of static on TV and radio since it is all digital nowadays.

Re: Webb and Hubble confirm Universe's expansion rate

#195

Post by ganzuul »

narag wrote: post #105
arcastroe wrote: post #46

I've asked this question before, but I don't think I received a good answer, so figured I'd try asking again. How do we know that galaxies are accelerating away from us and not moving at constant speed? People often point to the observation that the further away a galaxy is, the faster it appears to be moving away from us, implying acceleration. However, wouldn't we expect to see the same observation even without any…

How do we know that galaxies are accelerating away from us and not moving at constant speed? There's a more basic question: How do we know the galaxies are moving? It seems (I haven't seen any other response, like... ever) that we have one and only one way to measure the speed of galaxies: the red shift. It's impossible to triangulate those huge distances and the time scale would also be a barrier, so no way of confi…

> "we don't know any other reason for the light to red shift"

https://en.wikipedia.org/wiki/G%C3%B6del_metric

There are versions of this which do provide another reason for red shift.

Personally I keep this in mind as a means to free my thinking from a single narrative.

Re: Webb and Hubble confirm Universe's expansion rate

#197

Post by pigpang »

a_random_canuck wrote: post #145
westurner wrote: post #18

Hubble's law: https://en.wikipedia.org/wiki/Hubble%27s_law Expansion of the universe: https://en.wikipedia.org/wiki/Expansion_of_the_universe : > While objects cannot move faster than light, this limitation only applies with respect to local reference frames and does not limit the recession rates of cosmologically distant objects Given that v is velocity in the opposite direction, and c is the constant reference fram…

> do we account for velocity in determining whether light traveling at c towards earth will ever reach us? No, because the speed of light is constant for all observers. From our frame of reference on earth, light from distant receding galaxies is always moving towards us at exactly the speed of light, c. Those galaxies also observe the light moving away from them at exactly c. That seems contradictory and unintuitive…

> That seems contradictory and unintuitive, that two observers moving away from each other both measure light moving c relative to themselves, but that’s reality.

Light is a wave. Photon is a complex thing (Hopfion?), but it's a wave, so it waves something, a medium. Speed of wave propagation in a medium is constant. IMHO, it's intuitive.

Re: Webb and Hubble confirm Universe's expansion rate

#198

Post by jon_adler »

merek wrote: post #190

For those interested in the cosmic distance ladder, David Butler has an excellent youtube series "How far away is it?", detailing the methods used to estimate distance along the cosmic distance ladder, the history, and examples. I highly recommend. https://www.youtube.com/playlist?list=PLpH1IDQEoE8QWWTnWG5cK...

Thank you. This series of videos is extremely helpful for understanding the concepts referred to in the article.

Re: Webb and Hubble confirm Universe's expansion rate

#199

Post by [deleted] »

physicles wrote: post #169

The article mentions the cosmic distance ladder, which is one of my favorite things in all of science. How do we know how far away the really far stuff is? It's non-trivial and I find the history fascinating. It all started with knowing the distance from the earth to the sun. Nobody had a clue until Richer and Cassini got within 10% in 1672. Then we nailed it down in 1769 with James Cook's voyage to Tahiti, the prima…

[deleted]

Re: Webb and Hubble confirm Universe's expansion rate

#200

Post by LilBytes »

orlp wrote: post #194
theoreticalmal wrote: post #141

Earlier quoted context omitted.

I can’t believe it. First they take Pluto from us, next they’re going to tell me the static on my tv set isn’t the remnants of the Big Bang, but just hot dust? My childhood is crumbling!

Your comment made me realize how some younger people have no idea of, or at least no first-hand experience of static on TV and radio since it is all digital nowadays.

My great grandparents had a black and white TV when I was a toddler, and I'm 36!

The amount of change millennials and the generations before and after us have seen is boggling.

I was out in country Victoria, Australia a few months back and the internet was TERRIBLE. I'm talking, JPG's loading line by line terrible. And this was on 'alleged' 4G.

I felt pretty nostalgic for all of 2-3 minutes before I started pulling my hair out. I feel nostalgic about it again now.

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