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James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

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Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#81

Post by qqtt »

wutwutwat wrote: post #68

But what is it expanding into? If the universe is expanding like a balloon then there's some sort of "edge". What is that edge expanding into? Imagine we had a craft that could take us to the edge and you could stand on it, the way you place your finger on the outside of a balloon. If you could stand on the outside/edge of the expanding universe, what would you see, that we're expanding into? It can't be nothing. Som…

Like a lot of language we use when discussing things at the universe scale, the word “expanding” operates as a placeholder with analogs in day to day life but isn’t a perfect representation of what we mean.

The “universe” itself is space and time. When we say “expanding” we simple mean that galaxies are observed to be moving farther away from each other. That does not at all imply some kind of “expansion into another space” - space itself is exhibiting this property and we are observing it. That’s all.

The “balloon” analogy and the usage of the word “expand” in this context are both imperfect metaphors for physical phenomena we are observing.

It is a bit like trying to discuss what happened “before” the Big Bang - there is no “before” - time was created.

There are many phrases you can construct which may seem like they “make sense” but are actually combining a set of word concepts in ways that are self-contradictory.

“What is space expanding into?”

“What happened before time was created?”

Etc.

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#82

Post by foobarian »

epgui wrote: post #37
foobarian wrote: post #29

I get that the universe can be expanding, and that there might be different methods to calculate/measure this that have discrepancies. But that the rate of expansion is accelerating , how in the world is that possible?

What makes you think that should not be possible? It's a pretty well accepted fact.

I don't think it's not possible, I just find it surprising based on the layman understanding that gravity is a dominant force at long distances, leading me to believe that expansion should be slowing.

I also have the layman awareness of some kind of missing mass sometimes explained by "dark matter." But I did not see the additional explanation that this "dark matter" also acts as a repulsive force to accelerate the expansion. Maybe large scale structures manage to create propulsive forces that happen to point away from the center? Anyhow I would love to know what the mechanism is there.

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#83

Post by wutwutwat »

Night_Thastus wrote: post #77
wutwutwat wrote: post #68

But what is it expanding into? If the universe is expanding like a balloon then there's some sort of "edge". What is that edge expanding into? Imagine we had a craft that could take us to the edge and you could stand on it, the way you place your finger on the outside of a balloon. If you could stand on the outside/edge of the expanding universe, what would you see, that we're expanding into? It can't be nothing. Som…

I don't agree. You're assuming that the universe is a distinct 'something' expanding into a distinct 'nothing'. I disagree, I think that the 'universe' is an arbitrary border we created. If we were somehow able to accelerate a particle out past the edge of the known universe, now the bubble includes that particle too and essentially we've 'expanded' the universe. In other words, the arbitrary bubble containing things…

> I think that the 'universe' is an arbitrary border

I don't think that the scientific definition of the universe matches this. It's a physical thing, not a construct we made up. It's not an imaginary line between two countries.

The universe is full of things which have mass. Those things are rapidly expanding outward. What are those masses expanding into as they "blow up the ballon" and push the boundaries of the universe outward? It can't be nothing, it's physically impossible.

EDIT: might as well quote people smarter than I

> The universe is all of space and time[a] and their contents.[10] It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of energy and matter, and the structures they form, from sub-atomic particles to entire galaxies. Space and time, according to the prevailing cosmological theory of the Big Bang, emerged together 13.787±0.020 billion years ago,[11] and the universe has been expanding ever since. Today the universe has expanded into an age and size that is physically only in parts observable as the observable universe, which is approximately 93 billion light-years in diameter at the present day, while the spatial size, if any, of the entire universe is unknown.

https://en.wikipedia.org/wiki/Universe

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#84

Post by digging »

mr_mitm wrote: post #74
JoeOfTexas wrote: post #70

Earlier quoted context omitted.

If expansion at the big bang started with a rate of X. Could the varying densities at different points cause their expansion to deviate from the original rate?

I'm not sure what exactly you mean, but the Hubble tension could also be explained if we live in a particularly large under dense region of the universe. Then the light we observe from the CMB basically has to climb out of a gravitational well which would influence our measurement. IIRC such a substantial under density is considered unlikely though and very hard if not impossible to measure. The spatial inhomogeneiti…

> I'm not sure what exactly you mean, but the Hubble tension could also be explained if we live in a particularly large under dense region of the universe.

That would be the proposed Local Hole.

[1]https://en.wikipedia.org/wiki/KBC_Void

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#85

Post by 16bytes »

wutwutwat wrote: post #68

But what is it expanding into? If the universe is expanding like a balloon then there's some sort of "edge". What is that edge expanding into? Imagine we had a craft that could take us to the edge and you could stand on it, the way you place your finger on the outside of a balloon. If you could stand on the outside/edge of the expanding universe, what would you see, that we're expanding into? It can't be nothing. Som…

The balloon analogy is a 2 dimensional example. If you are on the surface of the balloon, there is no "edge". You can go forever in any direction. If the balloon is inflated, it doesn't expand into something (remember we're in a 2D space, it's not a 3D balloon), it "expands into itself".

If you drew two dots on the surface of that balloon, those dots would get further apart as it inflated. What did those dots expand into? Well, nothing right? They just got further apart from each other on the balloon.

So, if you translate this into 3D space, that's what's going on. It's hard to visualize. It's not that the universe is expanding into something, it's that the space between every "point" in the universe is getting further apart.

https://bigthink.com/starts-with-a-bang/what-universe-expand...

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#86

Post by layer8 »

wutwutwat wrote: post #68

But what is it expanding into? If the universe is expanding like a balloon then there's some sort of "edge". What is that edge expanding into? Imagine we had a craft that could take us to the edge and you could stand on it, the way you place your finger on the outside of a balloon. If you could stand on the outside/edge of the expanding universe, what would you see, that we're expanding into? It can't be nothing. Som…

It doesn’t expand into anything. It has no edge. It expands within itself, like it’s distorting itself. Alternatively, you can picture it as groups of gravitationally bound objects (= galaxy clusters) moving away from each other everywhere in the universe. It’s a bit like raisins in a cake being carried away from each other by the dough expanding in the oven. Where the cake already fills all space infinitely in all directions, from the very start. Space is the cake dough. There is no “outer” space that space expands into. The geometry of space itself expands.

Still alternatively, imagine an infinitely extended graph paper whose grid size slowly and continuously increases, carrying with it the dots already drawn on it. Since the grid has infinite size from the start, it doesn’t expand into anything. It just expands.

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#87

Post by wutwutwat »

16bytes wrote: post #85
wutwutwat wrote: post #68

But what is it expanding into? If the universe is expanding like a balloon then there's some sort of "edge". What is that edge expanding into? Imagine we had a craft that could take us to the edge and you could stand on it, the way you place your finger on the outside of a balloon. If you could stand on the outside/edge of the expanding universe, what would you see, that we're expanding into? It can't be nothing. Som…

The balloon analogy is a 2 dimensional example. If you are on the surface of the balloon, there is no "edge". You can go forever in any direction. If the balloon is inflated, it doesn't expand into something (remember we're in a 2D space, it's not a 3D balloon), it "expands into itself". If you drew two dots on the surface of that balloon, those dots would get further apart as it inflated. What did those dots expand…

> The balloon analogy is a 2 dimensional example. If you are on the surface of the balloon, there is no "edge". You can go forever in any direction. If the balloon is inflated, it doesn't expand into something (remember we're in a 2D space, it's not a 3D balloon), it "expands into itself".

I'm talking about 3d that we live in. We're currently standing on a ball of dirt, if the earth started to swell up, the surface we're standing on would expand into space. The thing we're standing on that's pushing outward is what I mean by "edge".

What is the universe expanding into? If it's pushing outward in all directions, it's pushing into something, the same way a swelling earth would expand into space

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#88

Post by wutwutwat »

layer8 wrote: post #86
wutwutwat wrote: post #68

But what is it expanding into? If the universe is expanding like a balloon then there's some sort of "edge". What is that edge expanding into? Imagine we had a craft that could take us to the edge and you could stand on it, the way you place your finger on the outside of a balloon. If you could stand on the outside/edge of the expanding universe, what would you see, that we're expanding into? It can't be nothing. Som…

It doesn’t expand into anything. It has no edge. It expands within itself, like it’s distorting itself. Alternatively, you can picture it as groups of gravitationally bound objects (= galaxy clusters) moving away from each other everywhere in the universe. It’s a bit like raisins in a cake being carried away from each other by the dough expanding in the oven. Where the cake already fills all space infinitely in all d…

> It doesn’t expand into anything. It has no edge. It expands within itself, like it’s distorting itself

That's not an explanation, that's incoherent ramblings that make zero logical sense

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#89

Post by layer8 »

wutwutwat wrote: post #88
layer8 wrote: post #86

Earlier quoted context omitted.

It doesn’t expand into anything. It has no edge. It expands within itself, like it’s distorting itself. Alternatively, you can picture it as groups of gravitationally bound objects (= galaxy clusters) moving away from each other everywhere in the universe. It’s a bit like raisins in a cake being carried away from each other by the dough expanding in the oven. Where the cake already fills all space infinitely in all d…

> It doesn’t expand into anything. It has no edge. It expands within itself, like it’s distorting itself That's not an explanation, that's incoherent ramblings that make zero logical sense

The math from general relativity is crystal clear. It’s just difficult to translate into natural language, because it doesn’t match our intuitions, which are primed by local experiences of non-curved space. You have to question your intuitions, and if you’re serious about it, look into the actual math. It all follows from a few basic assumptions, and is consistent with actual observations to an unmatched degree.

Re: James Webb Telescope Confirms That the Universe Is Expanding at Different Speeds

#90

Post by rainbowzootsuit »

spenczar5 wrote: post #12
cl42 wrote: post #6

Can someone more familiar with the science help me out? - On the one hand, the universe can be expanding at different rates. - On the other hand, is it possible our approach to measuring the expansion (e.g., using Cepheid variable stars) might be the problem?

We don’t really know - you are right to ask this question. There are two methods and they disagree with each other. JWST is precise enough to rule out a simple reason like instrument imprecision. So remaining possibilities are new physics, a deep flaw in our assumptions/methods, or a universe which is not uniform (but in a peculiar way).

Perhaps the small anisotropy that is observed in cosmic microwave background observations imprints to the dark energy that accelerates expansion. I haven't kept up on the modern state of the art.
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