Both papers are about dividing up the experience of living into a measurement/location map. Should measurement be given ontological status? This is the heart of Zeno's paradoxes. Are there infinite points or only one indivisible space. Are there infinite moments or one one indivisible duration. The answer is profound.

When I am driving, and observe out of my windshield, I see a two dimension space that is changing with duration. It is like a moving picture. This experience is much different than one when I try to map my coordinates using measurements where I used coordinate axis as you describe. Describing an experience is not the experience itself, which is why I continue to believe that mathematics does not provide an ontological view of the nature of nature's. It gives the opposing views. This is fundamental because living and experiencing is beyond the reach of measurements.

Now, scientists are beginning to look at the universe differently. As a hologram with one less dimension than conventionally understood space. A bit closer to the actual experience but ultimately whatever science comes up with will necessarily rely on mathematics and thus will be far from experience. Mathematics is only about partitioning and measurement. It cannot capture living experience. The only way to understand the living nature is via direct observation coupled with intuition

I think you should remember that we are talking about science, and not experience. The discussion which of the two is closer to reality sounds like a metaphysical conundrum. Don't make it a competition between knowledge and intuition like Bergson much too easily did. As far as I am concerned, they feed on each other. Knowledge is as primitive as intuition, and to be able to gauge distances is a condition for survival.

Science provides some practical tools that can be developed based upon creative insights, but these tools acting on the the experience are not the experience itself. We have become so infatuated with the tools (e.g. computers, drugs) that we have lost all sight and insight into the experience of life itself, replacing life with the tool.

The basic tools of science always begin with a new creative insight and it's a continuum, but the tools are not a prerequisite for understanding, they are only tools to play with.

The Daoists, who were great observers, developed a tremendous understanding of the nature of life. What they couldn't do is kill millions of people with a single gadget. That took a better understanding of chemistry (which begins with direct observation and intuition, e.g. alchemy). Unfortunately, much ancient knowledge which is quite superior is being lost. The good news is that it can be recovered by direct observation and creative intuition.

The Daoists, who were great observers, developed a tremendous understanding of the nature of life. What they couldn't do is kill millions of people with a single gadget. That took a better understanding of chemistry (which begins with direct observation and intuition, e.g. alchemy). Unfortunately, much ancient knowledge which is quite superior is being lost. The good news is that it can be recovered by direct observation and creative intuition. — Rich

I am afraid I do not share such a romantic view of ancient knowledge.

Different life experiences. I am much more interested in life than in gadgets. I have discovered that there is much, much more good health and joy in dance, singing, and the arts than can be found in gadgets. Quality trumps quantity, and life trumps science.

I am much more interested in life than in gadgets. I have discovered that there is much, much more good health and joy in dance, singing, and the arts than can be found in gadgets. Quality trumps quantity, and life trumps science. — Rich

nothing wrong with that.

Please read the previous posts. You barge in and expect us to start all over again. That is not reasonable. — Hachem

How can Apokrisis be barging in? Back on Page 1, I asked him to participate:

As I said before, we'll have to wait for someone who knows more than I to carry this on further. — T Clark

One explanation is that it is moving away from you very fast, or another explanation is that you are moving away from it very fast. Directionality is the key here. — MikeL

No, directionality doesn't really matter in that sense, since everything is moving away from everything, as the evidence suggests.

They could also all be contracting toward their centre, in which case they are also all moving away from each other. — MikeL

No, I don't think that that's right. In that case, they would not all be moving away from each other. The movement can be visualised if you imagine a cone, with the tip of the cone being the centre to which the points are all travelling. Or if you imagine the rings on a tree trunk. The closer to the tip, or to the centre, the closer together the points would be, eventually.

Expansion, further apart; contraction, closer together. Although it's not as simplistic as that because of the differing speeds, collectively, that's how it would be.

Imagine space as a matrix full of dots or circles. The dots are contracting away from each other, the centre most parts contracting fastest.

But say you could establish a contraction scenario that is exactly symmetric to the expansion scenario, what have you achieved but another way of saying the same thing? It wouldn't advance the science if it hasn't changed the science.

Under general relativity, the universe could be expanding or contracting. GR equations famously have symmetry in that precise regard. They don't specify a direction, so both directions make sense.

However the two directions make different predictions once we add in a conservation of energy constraint. Now one direction will cool radiation by stretching it, or redshifting it. The other will heat radiation by contracting it, or blue-shifting it.

So we looked up in the sky and saw unambiguously which it was. The Universe is redshifting evenly in every direction. At most, this would mean the earth just happens to be standing still as it sits right in the centre of the universe and everything else is for some reason moving away with ever greater speed according to it distance. So everything else is not just moving with some constant velocity but is carefully arranged so that velocity is faster the further away the object happens to be.

This kind of Copernican special arrangement doesn't generally make good science. It is simpler to believe that space expands the same for everyone everywhere at the same local rate. There is no centre to the expansion, and so no need to locate the earth in exactly that one spot.

Then again, even if the earth is in this special Copernican situation, we are not seeing the blueshift a generalised contraction ought to predict. The stars are not carefully arranged so that the most distant look to be rushing towards us the fastest.

Imagine space as a matrix full of dots or circles. The dots are contracting away from each other, the centre most parts contracting fastest. — MikeL

No, the dots would not be contracting away from each other, except in the very limited sense, which I acknowledged, that some dots would be moving away from some others, because they'd be travelling at different speeds.

Collectively, however, they'd all be drawn towards a single point, the centre, and thus they'd ultimately be getting closer together, as they would in a reverse Big Bang. They'd all be headed towards the same destination, not away from it; and they wouldn't all be moving away from each other, as illustrated in the balloon demonstration. Or, to go back to the tree trunk, each of the rings on the tree trunk would shrink inwards towards the centre.

When you talk about contraction, I think of a Big Crunch scenario. What other scenario could it be?

But say you could establish a contraction scenario that is exactly symmetric to the expansion scenario, what have you achieved but another way of saying the same thing? It wouldn't advance the science if it hasn't changed the science.

However the two directions make different predictions once we add in a conservation of energy constraint. Now one direction will cool radiation by stretching it, or redshifting it. The other will heat radiation by contracting it, or blue-shifting it. — apokrisis

If it's perfectly symmetric there is no blue shifting. The opposite of space itself expanding is space itself contracting. Because everything in that space is also contracting, there is no heating. The galaxy will not pull away from us, anymore than it is drifting towards us now under an inflationary model. The contraction doesn't have to be directional toward a centre point.

If it can be agreed that it can happen, then I can suggest one way it will change our understanding of science.

In a contracting model, the ratio of distances only grows larger, just as in expansion --> no heating

Sorry, you are wrong. Wiki has spoken....

In a hypothetical universe undergoing a runaway big crunch contraction, a cosmological blueshift would be observed, with galaxies further away being increasingly blueshifted; the exact opposite of the actually observed cosmological redshift in the present expanding universe.

https://en.m.wikipedia.org/wiki/Blueshift

You're missing the concept. This is all the parts of space rushing towards a single centre with those on the outer edges rushing in the fastest. That is not what I am saying at all.

In my model the centre is shrinking the fastest, but there is no single centre as all of space is contracting. So throw the 1980s checkerboard cloth over space and then contract all of the checkers. The ones in the centre smallest, the ones on the outer fringe the largest. The checkerboards don't overlap, there is no compression as all of the space inside the checkerboard is contracting too.

Wait a second I rushed that answer back. I forgot I'm using the no single centre model.
In the checkerboard table cloth each checker would be pulling away from its checkerboard border and contracting.

Actually, never mind, it's not important. I just realised it is an energetic boundary I am wrestling with, not a spatial one.

Yes, click the link where it says "expanding universe" and you will find Wiki understands this too....

The metric expansion of space is the increase of the distance between two distant parts of the universe with time.[1] It is an intrinsic expansion whereby the scale of space itself changes. It means that the early universe did not expand "into" anything and does not require space to exist "outside" the universe - instead space itself changed, carrying the early universe with it as it grew. This is a completely different kind of expansion than expansions and explosions we see in daily life. It also seems to be a property of the entire universe as a whole rather than a phenomenon that applies just to one part of the universe or can be observed from "outside" it.

https://en.m.wikipedia.org/wiki/Metric_expansion_of_space

Got it. Thanks for your help.

Hey, you're welcome.

The contraction doesn't have to be directional toward a centre point. — MikeL

No, I suppose not, but that'd make more sense, wouldn't it? I'll go with what makes more sense. Anyone can come up with ideas like that or like your petrol can, but if they don't really add anything, or, worse, if they actually detract from what we have, and create more problems than resolutions, then that doesn't go in their favour. Raising possibilities is one thing, solving problems is another.

In a contracting model, the ratio of distances only grows larger, just as in expansion — MikeL

I still don't understand how you're reaching that conclusion.

Take a look at the The Universe as a Gas Can - Part One: Entopy OP Sapientia.

Maybe I will, but this discussion is about the contraction of the universe, and I still have queries about what you've said in that regard.

In a contracting model, the ratio of distances only grows larger, just as in expansion
— MikeL
I still don't understand how you're reaching that conclusion. — Sapientia

It apparent growth in the ratio would be a summative effect over distance. Apokrisis has steered me right though on this point. You are welcome to check out the previous comments.

Anyone can come up with ideas like that or like your petrol can, but if they don't really add anything, or, worse, if they actually detract from what we have, and create more problems than resolutions, then that doesn't go in their favour. Raising possibilities is one thing, solving problems is another. — Sapientia

Go on, check it out, and then tell me that I was full of shit.

It apparent growth in the ratio would be a summative effect over distance. — MikeL

That's the conclusion. I'm asking you how you got there, but instead you're just repeating it, which wastes both of our time. You made the claim, and I've challenged it. The burden is on you. Are you incapable or unwilling?

I could look further into it on my own, but if you said it, then it's charitable to give you the benefit of the doubt that you know what you're talking about and can answer my question.

Apokrisis has steered me right though on this point. You are welcome to check out the previous comments. — MikeL

I have. He said that you were wrong.

I looked up the article about blue shift, and I understand what that means:

A blueshift is any decrease in wavelength, with a corresponding increase in frequency, of an electromagnetic wave; the opposite effect is referred to as redshift. In visible light, this shifts the color from the red end of the spectrum to the blue end.

The other article he linked to was about expansion, but my query is about what you've said in relation to contraction.

Are you incapable or unwilling? — Sapientia

Honestly Sapientia, I'm unwilling. I could explain to you what I mean in more detail, I usually enjoy doing that a lot, but I do not think you have come here and are asking these questions in good faith, which is disappointing. Initially I did think you were interested which is why I included you in my responses.

I thought you were trying to be objective and were interested in the subject, but now I think you're just fishing about for something that makes you right and me wrong. I don't like that attitude in people - it's about as closed minded as you can get. The forum is about the exchange of ideas, Sapientia.

Regarding the comments you made about my other OP in this thread, I found them unnecessary and aggressive, and I have directed you to the reposted OP to ask if you stand by the claims you made earlier of not having enough knowledge or qualifications to broach the subject and whether you think it is still bizarre arm chair science. You've not answered, and I suspect that any answer you give will try and support your position - perhaps in a sentence I didn't dot an 'i' somewhere. You just can't admit you might have been wrong about me. I have no respect for that.

Suit yourself. In response, I will simply note the irony in insinuating that I am close-minded right after openly admitting to closing your mind to the possibility that I'm pursuing this inquiry in good faith.

Never mind. I will look further into it myself.

The whole of space can expand and contract. Furthermore, Einstein’s equation shows that space cannot stand still; it must be expanding. In 1930 the expansion of the universe was actually observed. The same equation predicts that the expansion ought to have been triggered by the explosion of a young, extremely small and extremely hot universe: by what we now know as the ‘Big Bang’. Once again, no one believed this at first, but the proof mounted up until cosmic background radiation – the diffuse glare that remains from the heat generated by the original explosion – was actually observed in the sky. The prediction arising from Einstein’s equation turned out to be correct. — Carlo Rovelli, Seven Brief Lessons On Physics

So, there we have it. Einstein's equation shows that the universe must be expanding, and this expansion has been observed.

The more we learn about Einstein's equation, the better our understanding of why it is that the universe must be expanding.

Or, perhaps this recognised theoretical physicist has got it wrong.

All of this is the result of an elementary intuition: that space and gravitational field are the same thing. And of a simple equation which I cannot resist giving here, even though you will almost certainly not be able to decipher it. Perhaps anyone reading this will still be able to appreciate its wonderful simplicity:

R ab − ½ R g ab = T ab

That’s it.

You would, of course, need to study and digest Riemann’s mathematics in order to master the technique to read and use this equation. It takes a little commitment and effort. But less than is necessary to come to appreciate the rarefied beauty of a late Beethoven string quartet. In both cases the reward is sheer beauty, and new eyes with which to see the world. — Carlo Rovelli, Seven Brief Lessons On Physics

Did you maybe wonder whether the universe is changing at all?

I am not saying it is not. I have no way of knowing that.

It is just that the whole argumentation, just like the whole of cosmology, depends on whether light is like the theory says it is.

All my threads attempt to show that this is far from obvious and beyond doubt.

So, there we have it. Einstein's equation shows that the universe must be expanding, and this expansion has been observed. — Sapientia

That's an over-simplification by Rovelli.

As he does state in his first sentence, general relativity's field equations don't define a direction. The Universe could be expanding or contracting.

And Einstein's first thought was that - because of the Universe's gravitational content - it would naturally be contracting. Einstein believed the Universe ought to be eternal and standing still, so he added an extra term to his GR equation - the cosmological constant - as an extra mystery force required to exactly counteract that gravitational collapse and so allow the Universe to be static.

It was an embarrassing kluge factor. It couldn't even work as this static solution was so unstable that the universe would have to tip over into gravitational collapse with the slightest inhomogeneities in the spread of gravitating matter.

But then it turned out from observation - red-shifted stars - that the Universe was in fact expanding. So that wasn't predicted by anything in Einstein's equations. Although it was certainly allowed. And the Big Bang theory was born, where now there had to be a fantastically accurate balance between the outward force, the kinetic energy, of "an explosion", and the contracting force of any gravitational contents - the total mass of the Universe.

Roll forward and the Universe proved to have only about 30 per cent of the required mass at best. Then observation suggested the solution - dark energy, a repulsive force creating a faint acceleration at every point of space. And now this had to be incredibly balanced or fine-tuned ... due to some quantum explanation so far eluding physics.

So expansion is certainly a reasonable conclusion. It is what we see when we look at the stars and galaxies.

But gravity says basically things ought to be contracting. And then a static Universe - the most "obvious" presumption - is impossible. Eternal existence is ruled out as a maximum improbability.

And if there is the third option of expansion - as there really must be just because it is both what we can see, and what is most probable given the Universe has been around long enough for us to be even wondering - then this expansion must be most remarkably fine-tuned. The expansion - or indeed now, the acceleration - is adjusted to be exactly the amount needed to make the Universe almost perfectly flat and future eternal.

The details are worth going into as this is a cosmic scale whodunnit. It shows how poor our metaphysical intuitions can be. It shows why proper science is actually needed. :)

So MikeL I would credit for at least having a go at being bothered by the basic claim - why is the Universe expanding rather than shrinking?

The actual physics has long moved on. The question now is why is it faintly accelerating by some precisely correct amount to make up for the 70 per cent of "missing mass". There is plenty of speculation about possible answers, but right now it is simply a really big and interesting gap in our scientific knowledge.