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Analysis indicates that the universe’s expansion is not accelerating

ras.ac.uk

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Re: Analysis indicates that the universe’s expansion is not accelerating

#41

Post by Sharlin »

xoa wrote: post #27
Sharlin wrote: post #16

Earlier quoted context omitted.

Edit: A big brain fart, ignore the retracted part below. Colonizing the universe is of course impossible in 100My, barring FTL. What the paper I referred to [1] says is that colonizing the Milky Way may take less than that, and if you can do that, spreading to the rest of the observable universe is fairly easy, very relatively speaking. According to some calculations, it should in principle be possible to colonize th…

> According to some calculations, it should in principle be possible to colonize the entire observable universe in less than a hundred million years ...what? That doesn't seem right, just from a really quick gut check it looks like the observable universe has a radius of 45.7 billion light years [0]. Even if the universe wasn't expanding nobody could get to everything any faster than that number of years right? Maybe…

Oops, yes, I don't know what I was thinking. A total brain fart. The paper I referred to is Sandberg and Armstrong's 2012 "Eternity in Six Hours", and of course they don't claim such a thing. Only that it's possible to start a colonization wave that has plenty of time to spread to everything visible now before they slip outside of our future light cone. The ~100M years refers to the colonization of the Milky Way. Sorry!

[1] https://www.sciencedirect.com/science/article/abs/pii/S00945...

Re: Analysis indicates that the universe’s expansion is not accelerating

#42

Post by pdonis »

jimbo808 wrote: post #15

Anyone know how credible this is? If true, then that means the big bounce is back on the menu, and the universe could actually be an infinitely oscillating system.

> Anyone know how credible this is?

AFAIK the previous models that all assumed that Type 1a supernovae were not affected by the age of the progenitor stars had no actual analysis to back that up; it was just the simplest assumption. This research is now actually doing the analysis.

Re: Analysis indicates that the universe’s expansion is not accelerating

#43

Post by mkl »

delta_p_delta_x wrote: post #25
Sharlin wrote: post #16

Earlier quoted context omitted.

Edit: A big brain fart, ignore the retracted part below. Colonizing the universe is of course impossible in 100My, barring FTL. What the paper I referred to [1] says is that colonizing the Milky Way may take less than that, and if you can do that, spreading to the rest of the observable universe is fairly easy, very relatively speaking. According to some calculations, it should in principle be possible to colonize th…

> The relative jump in difficulty from interstellar to intergalactic is much smaller than from interplanetary to interstellar. Interesting way to put it... This doesn't seem that accurate. With sufficiently advanced technology, many of which we already possess, we could expect to propel a minute spacecraft to a considerable fraction of the speed of light, and reach nearby stars possibly within the end of the century.…

If you can get to a star 100 light years away, you can get to Andromeda. It doesn't require going faster, just waiting longer.

Re: Analysis indicates that the universe’s expansion is not accelerating

#45

Post by mrbluecoat »

I have a great deal of respect for the sciences but sometimes astronomy just feels like one giant guessing game: age of the universe, big bang starting as a joke and all the "first minute" timelines thereafter, dark energy and dark matter (code for we have no idea what it is) vastly outnumbering everything else, and now questioning the Nobel Prize-awarded universe expansion. Meanwhile, asteroids the size of buses+ keep whizzing by closer than the moon with little or no warning. Sigh.

Re: Analysis indicates that the universe’s expansion is not accelerating

#46

Post by Sharlin »

hn_acc1 wrote: post #24
Sharlin wrote: post #16

Earlier quoted context omitted.

Edit: A big brain fart, ignore the retracted part below. Colonizing the universe is of course impossible in 100My, barring FTL. What the paper I referred to [1] says is that colonizing the Milky Way may take less than that, and if you can do that, spreading to the rest of the observable universe is fairly easy, very relatively speaking. According to some calculations, it should in principle be possible to colonize th…

I found someone saying colonize the Milky Way Galaxy in ~90m years? Is that what you meant? The observable universe is ~93B LY - unless you're assuming FTL (and MUCH faster than light), I don't see how that's possible?

Yes, my brain totally froze. Added a correction.

Re: Analysis indicates that the universe’s expansion is not accelerating

#47

Post by CamperBob2 »

khimaros wrote: post #31
jimbo808 wrote: post #15

Anyone know how credible this is? If true, then that means the big bounce is back on the menu, and the universe could actually be an infinitely oscillating system.

time to re-read "The Last Question"

"Sorry, but as a large language model, I cannot provide advice on how to reverse entropy."

Re: Analysis indicates that the universe’s expansion is not accelerating

#48

Post by CamperBob2 »

mrbluecoat wrote: post #45

I have a great deal of respect for the sciences but sometimes astronomy just feels like one giant guessing game: age of the universe, big bang starting as a joke and all the "first minute" timelines thereafter, dark energy and dark matter (code for we have no idea what it is) vastly outnumbering everything else, and now questioning the Nobel Prize-awarded universe expansion. Meanwhile, asteroids the size of buses+ ke…

That's a feature! If you want to be certain, you need religion, not science.

And of course, the people concerned with tracking near-earth asteroids are not connected in any way with cosmology.

Re: Analysis indicates that the universe’s expansion is not accelerating

#49

Post by skissane »

delta_p_delta_x wrote: post #25
Sharlin wrote: post #16

Earlier quoted context omitted.

Edit: A big brain fart, ignore the retracted part below. Colonizing the universe is of course impossible in 100My, barring FTL. What the paper I referred to [1] says is that colonizing the Milky Way may take less than that, and if you can do that, spreading to the rest of the observable universe is fairly easy, very relatively speaking. According to some calculations, it should in principle be possible to colonize th…

> The relative jump in difficulty from interstellar to intergalactic is much smaller than from interplanetary to interstellar. Interesting way to put it... This doesn't seem that accurate. With sufficiently advanced technology, many of which we already possess, we could expect to propel a minute spacecraft to a considerable fraction of the speed of light, and reach nearby stars possibly within the end of the century.…

I guess the question is… we know what our current propulsion technology is capable of… given a million years of further technological development, where will our technology be?

The idea that, given a million years of further technological development, intergalactic travel might actually be feasible, isn’t really that implausible. Far from certain, but far from implausible either.

And that’s the thing-a million years is a technological eternity, a rounding error in estimates of time to colonise the galaxy/the local group/the observable universe.

Re: Analysis indicates that the universe’s expansion is not accelerating

#50

Post by bombdailer »

aatd86 wrote: post #29

I would not be surprised if the universe was somewhat elastic, expands and then contracts and then expands ad infinitam. After all, existence in itself is irrefutable and cannot not exist by definition. If we subscribe to a theory of the multiverse, set theory, likelihood, and interaction driven evolution based on gradient type of fundamental laws. Locally changing. Obviously everything sharing a fundamental quality…

Eventually we will find that the heat death of the universe and the big bang are the same thing, since the totality of the universe is always a oneness, then from the universal perspective the infinitely small and infinitely large are the same thing (one), then they by nature bleed into (and define) each other like yin and yang.
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