How Big Is The Universe?

 
Rick Robson
 
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Rick Robson
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27 June 2021 21:01
 

Is the Universe infinite? Or does it somehow fold in on itself? And if so, in what shape?
Regardless of its shape, according to the most recent scientific researches, odds are that the Universe would expand forever. Furthermore, new fact checked evidences strongly reinforced again the not so new hints toward the paradoxal reality of an infinite Universe. Since forming some 13.7 billion years ago in the Big Bang, it has been expanding and may be infinite in its scope.

https://youtu.be/pn3euL8Tbfw

That’s a fantastic YT video about the thread’s subject, Prof. David Kipping closed it in such a sheer beautiful and creative way, hardly ever seen concerning general approach to science subjects. No doubt there’s clearly some inexorable philosophical facet to it, but then could the physicists, astronomers and cosmologists today indeed manage to be completely devoid from any kind of philosophical perspective given the overwhelming paradoxes being increasingly pointed out by the theoretical developments in special relativity, quantum mechanics, quantum field theories and so forth, more and more of them experimentally verified? Let alone the increasing capabilities of today’s telescopes that have been paving the way for revolutionary changes in our comprehension of the Universe and the way we see it.
Your thoughts please?

[ Edited: 27 June 2021 21:19 by Rick Robson]
 
MrRon
 
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MrRon
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28 June 2021 06:02
 

I think human brains are simply incapable of grasping a concept like “infinity”, in much the same way that your dog’s brain will never understand the Pythagorean Theorem. There may be a “simple” answer to the size and nature of the Universe, but truly understanding it would require an upgrade to our brain power. 

As far as physicists, astronomers and cosmologists of today, I don’t think they are devoid of any kind of philosophical perspective. In fact, I think having a philosophical perspective is unavoidable in those lines of inquiry. And it may be the very thing driving them to explore in the first place.

 

 
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EN
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28 June 2021 06:39
 

One thing that really interests me about the size of the universe is the idea that even though the speed of light is a theoretical limit on how fast something can go within this dimension, the universe itself is expanding, and at a rate greater than the speed of light.  You don’t really call that expansion a speed, but it does account for the universe being larger than the speed of light and the age of the universe would suggest.

 
Rick Robson
 
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Rick Robson
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28 June 2021 08:26
 
MrRon - 28 June 2021 06:02 AM

I think human brains are simply incapable of grasping a concept like “infinity”, in much the same way that your dog’s brain will never understand the Pythagorean Theorem. There may be a “simple” answer to the size and nature of the Universe, but truly understanding it would require an upgrade to our brain power.

I think you’re right, “infinity” is too abstract a concept for us to make up a good idea of it, let alone fully grasp it. Furthermore, its concept defies the fundamental “laws” of physics as it inexorably creates challenging paradoxes, the absolute limit for the speed of light being one of those physical rules.

MrRon - 28 June 2021 06:02 AM

As far as physicists, astronomers and cosmologists of today, I don’t think they are devoid of any kind of philosophical perspective. In fact, I think having a philosophical perspective is unavoidable in those lines of inquiry. And it may be the very thing driving them to explore in the first place.

That’s exactly my thoughts on this subject matter, it’s a proof to me that nobody can ever be completely devoid of some philosophical bias at all, it’s an inherent part of human rational thinking.

 

[ Edited: 28 June 2021 08:51 by Rick Robson]
 
Rick Robson
 
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28 June 2021 08:46
 
EN - 28 June 2021 06:39 AM

One thing that really interests me about the size of the universe is the idea that even though the speed of light is a theoretical limit on how fast something can go within this dimension, the universe itself is expanding, and at a rate greater than the speed of light.  You don’t really call that expansion a speed, but it does account for the universe being larger than the speed of light and the age of the universe would suggest.

The theoretical limit of the speed of light has been experimentally verified, Quantum Physics has been showing how chaotic our Universe would end up if anything was capable of surpassing the speed limit of ight. Experiments with atomic clocks proved how time itself lower its pace the faster the clock moves throughout the space dimension, fact checking what Einstein had already predicted with the spacetime concept of General Relativity, debunking Classical Physics fundamental rule that time is an autonomous and absolute entity. Quantum mechanics convincingly and coherently explains how time rather functions as a fourth dimension added to our 3D Universe. And today, physicists developed detailed studies on how paradoxal everything would become in our Universe—even our own individual lives—if an object of any dimensional size had the capability of travelling faster than the speed of light.

There’s a couple of YT videos by Arvin Ash that lucidly and in more detail explains what I’m saying, I sugget you check them out, they effectively analyse how the maximum speed limit is not a limit with which things can move, but is a limit on the speed of causality. He also further explains how instantaneous communication violates causality.

How Faster than Light Speed Breaks CAUSALITY and creates Paradoxes
https://youtu.be/mTf4eqdQXpA

4D Spacetime and Relativity explained simply and visually
https://youtu.be/ZfR1Jc6Zglo

[ Edited: 28 June 2021 09:20 by Rick Robson]
 
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28 June 2021 09:57
 

Yes, I’m not contesting the fact that the speed of light is what you say it is. But the radius of the universe is about 46.5 billion light years. But the universe has only been in existence about 13.7 billion years. So, light traveling in all directions for 13.7 billion years would render a universe with a radius for 13.7 billion light years in a non-expanding universe. Since it is a lot bigger than that, that shows you how it has expanded well beyond what light could travel in the same time. Since space-time itself it expanding, the speed of light remains constant. But the expansion is not bound by that speed.  Or, this is my understanding, which, of course, is not infallible.

 
Rick Robson
 
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28 June 2021 11:17
 

What if the next generation of telescopes find stars even older than the supposedly currently oldest one that David Kipping showed in his YT video aforementioned in the OP? That’s a plausible possibility also admitted by David as well, hinting towards an Universe even older than what’s currently known, concerning its age.

As for the speed of the Universe’s expansion, it’s actually been a hard issue for the scientific community to accurately solve. Among the methods astronomers have found to measure the expansion rate of our Universe (the Hubble constant), surface brightness fluctuations (SBF) is potentially one of the most precise, yet the new estimate based on these measurements highlights the mismatch with estimates from the early Universe, mind you. In fact, the ultimate recollected data confirm it’s expanding in an accelerated rate, seemingly caused by the permeating presence of what they call as “dark energy”.

[ Edited: 28 June 2021 11:21 by Rick Robson]
 
weird buffalo
 
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28 June 2021 11:20
 

You’re correct, the expansion of spacetime is happening at speeds much greater than the speed of light.  One of the interesting things on that, depending on how you measure the expansion rate the apparent rate is different.  Using the CMB, the current value of expansion is about 67 km/s per megaparsec of distance.  The previous method (that’s also constantly being improved) is the ladder method.  Measure the distance to something we can fairly reliably verify, and then using that to establish distances to things farther away.  Using this method, it’s recently been refined to 74 km/s per megaparsec.  Why these are different?  We don’t know.  But you’re right, in that a galaxy that is about 13-15 billion LY away, the space between it and us will be expanding faster than the speed of light, and the light from it right now will never reach Earth (or where Earth was, since the Sun will long ago have swallowed it by that point).

 
icehorse
 
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icehorse
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30 June 2021 11:08
 

Rick,

Fantastic video, thanks.

Questions about how the universe works on the large scale are fascinating. But I always feel like any absolute claims are extremely premature. I also add a parenthetical disclaimer whenever such claims are made, something like: we think X must be true of the expansion of the universe (based on the teeny, tiny bit we know).

 
 
Rick Robson
 
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30 June 2021 15:33
 
icehorse - 30 June 2021 11:08 AM

Rick,

Fantastic video, thanks.

Questions about how the universe works on the large scale are fascinating. But I always feel like any absolute claims are extremely premature. I also add a parenthetical disclaimer whenever such claims are made, something like: we think X must be true of the expansion of the universe (based on the teeny, tiny bit we know).

You are welcome icehorse. Sure, the faster that science gathers knowledge the faster it also gets more questions than answers…

 
Skipshot
 
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03 July 2021 00:58
 

Into what is the universe expanding?  Does it mean matter is expanding into nothingness?

 
Rick Robson
 
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03 July 2021 06:36
 
Skipshot - 03 July 2021 12:58 AM

Into what is the universe expanding?  Does it mean matter is expanding into nothingness?

But that’s precisely the major mystery—what in the Universe is actually the absolute nothingness? Both the observational and experimental evidences point to energy fluctuations inside what we conventionally define as total emptiness or nothingness. And even more puzzling is that it makes up approximately 70% of our entire Universe, and its effect is not diluted as the universe expands. The scientific community call it “dark energy”—https://youtu.be/8aHbLMUOwLc 
https://youtu.be/4TkyxLENS5Q

[ Edited: 03 July 2021 07:51 by Rick Robson]
 
weird buffalo
 
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03 July 2021 10:26
 
Skipshot - 03 July 2021 12:58 AM

Into what is the universe expanding?  Does it mean matter is expanding into nothingness?

Matter is not expanding.  Space is expanding.  While the exact volume of the universe might be influenced by forces acting upon it that are not contained within our universe, I think it’s safer to consider the volume as an independent characteristic of our universe.  It doesn’t need anything to expand it, as there’s no valid concept of “outside” that utilizes the three dimensions that we are used to.  If there’s an “outside”, it would by necessity not follow the current rules of our universe.  It could also have characteristics that describe the concept of volume within its rules, but likely they’d appear different to us.

 
weird buffalo
 
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03 July 2021 11:04
 

Spacetime youtube channel.

15-20 minute explainer videos on physics concepts.  I’ve only just gotten into this channel, and he moves pretty fast sometimes.  The production value is pretty good though, and he doesn’t get deep into the math, but does touch on it occasionally.