Important Video Source - don't miss it!

[Catastrophe]

I have just found a new (to me) source of videos with expert current researchers.
I am assuming that these videos are not generally known to the forum, else I am sure they would have been mentioned by now.

The one I have just been watching is from the World Science Festival (which is ongoing) and was made only just over a year ago, entitled: "Was the Big Bang the Beginning? Reimagining Time in a Cyclic Universe".

I was delighted to learn that some of my bête noire are being superceded - Big Bang and Inflation require a re-think - including difficulties such as entropy in cyclic models! These are available freely. This one about 90 minutes.

I shall be looking out for more, now I have found them. Here is the location of the one mentioned:

View: https://www.youtube.com/watch?v=MO3w2D3uDTw

New direct link.

You may have to C&P this to your prompt. You will have to SKIP onnly a couple of ads during the abt 90 minutes, and nothing is lost during these iinterruptions.

Cat

 

[Catastrophe]

I have just watched this video again, and an idea has struck me for an analogy which I find helpful.. But let me preface this immediately by saying that, whilst my thinking is entirely based on their brilliant work, the analogy is just what I thought to help me in my understanding. What I am making clear is that the theory is entirely theirs, but any inadequacy in the analogy is only my responsibility.

Going back to the flatlander analogy I have been discussing elsewhere, I found it helpful look at a lower dimensional appreciation of an observed universe (o/u) and see how it would appear to a being capable of appreciating a higher dimension. Now I am looking at a cyclic o/u in the same way. Say we have a flatlander living 'in' the surface of (what appears to us) as a sphere. We looked at this from a point of view of expansion, and saw that the surface of the sphere could expand, and the flatlander would know this from his/her observation that points on the surface of his/her sphere would move apart.

The flatlander could ask "Into what is my (observed) universe expanding? If a "universe" is all there is, But what is it expanding into? The observer, with more dimensional acuity, would say that the flatlander's o/u is very limited, and there are many FL o/u's forming a tiny part of my o/u. I can see what his o/u is expanding into, but I cannot see what my o/u is expanding into.

Now let us extend the question into "Can my universe be cyclic?" Now we see the flatlander's (observable) universe as a sphere. For the FL, it is as if (s)he lived on the surface of the Earth, but there was no "up or down" from that surface. But hold on to that for a moment. Say the FL's o/u is a spherical surface, but that surface is not perfectly smooth - like the Earth, it has hills and valleys. Those hills and valleys still have surfaces, and, in his/her o/u, the FL would still live in that surface - which (to us) is now a bumpy surface.

Now we can easily see how the FL's o/u can be cyclic. His/her surface (= observable universe) can now become more or less larger or smaller because it conforms to the bumps - although the F/L does not see them as bumps - just as variable surface area. Now we can easily see a F/L o/u based on the original smooth spherical surface, which we see as having the same radius, but which we see as cyclic expansions and contractions. To the F/L, these expanding and contracting bumps constitute expanding and contracting surface area, and thus his expanding and contracting "universe" (o/u). My understanding is that this is what the authors intend as contracting without collapsing.

Cat

 

[Catastrophe]

For those thinking twice about whether to watch this video, one of the professor guests has authored dozens of articles supporting cosmic inflation, and is here appearing in a program supporting the contrary.

I believe you will find it interesting, even if you hold a different opinion. It is well worth the time just for the interesting ideas and discussion generated.

View: https://www.youtube.com/watch?v=MO3w2D3uDTw

Cat

 

[Helio]

It looks like, in the past few months, that computer simulations have allowed the introduction of a model that addresses a key challenge in cosmogony -- homogeneity, or the smoothness we observe in the universe. This became crystal clear with the discovery of the CMBR, which varies by only 1 part in 100,000.

Their model, currently, works with contraction, hence this is more of a cyclical model, thus forgoing the requirement of a beginning, if that's possible.

It's argued that Inflation theory is, in Steinhardt's opinion, in serious trouble. He's convinced inflation would not smooth things, but make things worse.

However, Inflation theory is at a time far beyond modern physics. This would have happened at around 1E-35 sec, and the best CERN can address scientifically is at a time no sooner than 1E-12 sec. GUT (Grand Unified Theory) and TOE (Theory of Everything) "models" have attempted to unify all the forces of nature, but have yet to do so. What is really happening in this gray zone of time has not be remotely established and, worse, my prove to be untestable.

Nevertheless, in their efforts to work backwards, they believe they have a surprisingly robust model that smooths the universe as it contracts by taking on that which is in our horizon. They argue that the chaos can then be assigned, if I understand their reasoning, to regions in the other portions of our universe. This seems ad hoc. Why would our region be favored?

What they seem to show in the nice graphics is how contraction would produce the goal of having a smoother and smoother universe during slow contraction. They suggest that their initial conditions -- critical in any model -- are flexible enough to yield this smoothness.

It was mentioned that when scientists ask for their equations, the response is that equations are not needed; computer simulations are superior. Ug. Computers only produce results using equations, but they do this today at incredible speeds. [Thus, if the equations are inaccurate or incomplete, you can get a false result much, much quicker, and one can also far more easily produce the result one is chasing.]

It's noted, however, that they were surprised to see their smooth result. So it's likely they weren't trying to get to smoothness, but it found them. This helps support their view, IMO.

At the end there were some summaries. They admitted that the polarization found in the CMBR is evidence against their current model. This is a problem.

Also, when asked how a universe that is accelerating in its expansion could become a contracting universe, the answer was that we don't even know the expansion rate today since astronomers study SN that are billions of lightyears away, thus they only give the rate billions of years ago. This isn't correct. Astronomers (e.g. Slipher) first noted redshifts that strongly hinted as an expansion rate for galaxies beginning in 1912. Hubble used techniques that allowed astronomers to obtain far more accurate distances to define the expansion rate. Cepheids (per Leavitt), galactic magnitudes and sizes, blue star magnitudes, etc. were tools used to get the expansion rate of our more current universe. The use of SN did not change this but tweaked it.

But, when asked how the universe might start to contract, the answer was that, per the view above, that we may be slowing now and perhaps in only a few hundred million years we will begin our contraction. IMO, this isn't going to go well with astronomers. It's yet another example, as with Einstein initially, where theorists are a bit out of touch with astronomers.

 

[Catastrophe]

Helio, thank you for that contribution.

There is only one point in this video that really interests me, and that is that inflation seems to have been discredited. Most cogent of all is the fact that one highly reputable scientist, who has spent, I believe, decades in promoting inflation, has completely changed his opinion.

He said that, having worked in favour of inflation for a number of years (Google his name and 'inflation') he now thought it was unfixable. The problems with inflation (he said) have grown more and more, both in number and in severity. He sees it in very serious trouble and doesn't see it being fixed. He half said, just before this, "I personally don't think it can survi . . ." , and then changed it to the above.

That is more than enough for me to agree with what he stated.

Cat

 

[Helio]

Helio, thank you for that contribution.

There is only one point in this video that really interests me, and that is that inflation seems to have been discredited. Most cogent of all is the fact that one highly reputable scientist, who has spent, I believe, decades in promoting inflation, has completely changed his opinion.

That's an important point, but I suspect he has found a new shiny object to play with in the form of flexibility and elegance. The computer simulation seems to produce notable elegance that is not found in the current Inflation theory, apparently, contrary to others like Guth, I think.

Still, in a cyclical universe, this same elegance needs to be found for inflation (perhaps not The Inflation), which they seem to think they have in order to cycle back and forth for the universe, even if it's just our observable universe only, which adds to the ad hocness, IMO. [Is that a word?]

He said that, having worked in favour of inflation for a number of years (Google his name and 'inflation') he now thought it was unfixable. The problems with inflation (he said) have grown more and more, both in number and in severity. He sees it in very serious trouble and doesn't see it being fixed. He half said, just before this, "I personally don't think it can survi . . ." , and then changed it to the above.

Well, he does have incentive, along with some authority, to say it. But there are many variations to almost every early universe model. Winning these cosmologists over will take a lot of effort.

One problem that is perhaps the elephant in the room, and was barely addressed, is DE. What do they know about DE? Nothing is likely the answer, because no one knows much of anything about it, only that it's the label we assign to the force that is expanding the universe. Thus, if they want to claim the universe will slow and contract, and do it in a way that seems counter to the 2nd law, then they really need to explain DE. They didn't because, no doubt, they can't.

 

[Catastrophe]

Guess what? I just found another thread with a reply.

Ad hoc has no noun equivalent that I am aware of.
Maybe 'to the point' is a starting place (not a noun) but the point (of the conversation).
Not that close. Relevance is about my closest at the moment. Eric.

 

[Catastrophe]

Just checked my GCSE Latin. The noun (sometimes pronoun) of ad hoc is . . . . . . hoc.

In "English", perhaps gist. Some spontaneity is suggested. E.

 

[Helio]

Just checked my GCSE Latin. The noun (sometimes pronoun) of ad hoc is . . . . . . hoc.

In "English", perhaps gist. Some spontaneity is suggested. E.

The use of "ad hoc" is a term very common in science. The Merriam-Webster definition is, "for the particular end or case at hand without consideration of wider application."

My attempt to use "ad hocness" is to suggest a broader philosophy of its use, and more in a pejorative sense since "ad hoc" is a pejorative term. Those that have a habit of making ad hoc claims fall carelessly into using "ad hocness" in making claims.

I'm not pleased with it that much. I think most will understand its intended use, which is all words are good for, right? [This is no time to end with a preposition. ] Hopefully, you can offer something more appropriate. Remember, brevity is important.