Our ever expanding universe?

  • #1

Main Question or Discussion Point

The other day I saw Michio Kaku saying scientists now think that the universe "may have" started from being puked out by a blackhole from another universe. If this is correct could the answer to the question " why is the universe still expanding" be " It is still expanding because the said black-hole "is still spewing", into our universe, undetectable dark matter "that is still being devoured" in the universe in which it was born. If this correct it now begs for more answers to even more questions. For example: Could multiple black-holes be spewing into our universe at this very moment? :Could some black-holes in our universe be "giving birth" to new universes? : Are all black-holes the beginning of a new universe? The questions go on and on and on.... and these are just the questions coming from a dummy like me, lol, but you get the point!! I know I am not supposed to speculate but my curiosity has gotten the better of once again, lol,. I'm sorry if I am doing/done something wrong!!! Thank you!!!! Peace Brothers and Sisters!!!!!
 
Last edited:

Answers and Replies

  • #2
Drakkith
Staff Emeritus
Science Advisor
20,742
4,449
There is absolutely no way to know what goes on inside a black hole or whether we are in one ourselves or not. At least not currently as far as my limited knowledge on the subject goes. So the answer to your question is that we simply don't know.
 
  • #3
phinds
Science Advisor
Insights Author
Gold Member
2019 Award
15,907
5,585
Be aware that Michio Kaku is one of the very worst of the science popularizers. He loves throwing out far out theories that have little or no support in mainstream physics and presenting them as if they ARE accepted models. He also talks about some far out applications as though they were just around the corner.

He used to be a very serious and well respected scientists, but his activities over the last several years have seen him trashed pretty roundly on this forum.
 
  • #4
Be aware that Michio Kaku is one of the very worst of the science popularizers. He loves throwing out far out theories that have little or no support in mainstream physics and presenting them as if they ARE accepted models. He also talks about some far out applications as though they were just around the corner.

He used to be a very serious and well respected scientists, but his activities over the last several years have seen him trashed pretty roundly on this forum.
I became quite aware of this sites disdain for Mr.Kaku when I first joined in march of 2011. I must say it dumbfounds me how much the point really comes across in the forums. Still, we must not forget he is the father of string theory, which at first was scoffed at and then later accepted as being plausible. Thats just my take on things! What have the debunkers done that warrants them smarter than him. I don't see their names in the news or on tv. I mean, the guy has a big brain. It's obvious. He is open to conjecture and is not scared to speculate, which is what one must do when science cannot answer that which is being asked. As you can see he said scientists, which is plural, which means he is not alone in this speculation. He didn't say "I" or "me". I refuse to believe a man like him (he is a top physicist after all) is being marginalized and "shunned" when more should take his lead. Not everything is hard science. I'm sure he must have some, however little, to base these speculations on. I remember, when I was here back in march and april, touching on the possibility that our universe may have started this way. My how things change and make you go hmmm!!! Thank you!!!! Peace Brothers and Sisters!!!!!
 
  • #5
phinds
Science Advisor
Insights Author
Gold Member
2019 Award
15,907
5,585
Your faith in him is touching, but unfounded I think.

Speculation is one thing, and not a bad thing. Presenting speculation as solid science IS a bad thing and that's what he does. He does his science discussions at Star Trek conventions.
 
  • #6
Your faith in him is touching, but unfounded I think.

Speculation is one thing, and not a bad thing. Presenting speculation as solid science IS a bad thing and that's what he does. He does his science discussions at Star Trek conventions.
Hahaha, I know what you mean!! I have seen him on televisions "sci-fi science" where he offers "wild speculations" to "people dressed in funny space attire" lol. Regardless, what you or I anyone thinks it still doesn't make him a blithering idiot. If he doesn't have the solid evidence to prove his theories then someone must be able to solidly disprove them, right?. Don't get me wrong, I concur, on the television show he hosts, some of the theories do seem crazy and outlandish, but so did radio. I like Michio because his mind is always in the same state it was in on the day he told his mom he was building an atom smasher( or some such thing) in their garage. In my honest opinion, the only problem is it is not yet possible to attain the energy, power, electricity or pressures required for him to find out if his theories are correct or not. There!! That's all the bad I can say about him,lol. I mean, hasn't the guy earned degree upon degree? Like, ya' gotta' respect that, hey?? Peace!!!!! P.S. Let's get this back on topic thanks!!
 
  • #7
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
Well your posts make me think that you have intelligence and independent spirit. And your profile says cabbie with educational background none. And you are interested in what are called "bounce" scenarios.

I think you need exposure to other sources of information about bounce cosmology besides what you get on television.

I am going to suggest that you get a popular book from the library (but don't buy it) which is about the kind of bounces you are talking about (black hole collapse rebound to big bang). BUT I am first suggesting something much more challenging.

I suggest you learn how to use the InSpire search tool to access the professional research literature and don't try to understand every detail, just look over the titles and summaries to get an idea. Here is a sample search:

http://inspirehep.net/search?ln=en&ln=en&p=d+2010+and+k+quantum+cosmology+and+loop+space&action_search=Search&sf=&so=d&rm=citation&rg=100&sc=0&of=hb

d means "date" and k means "keyword"
quantum cosmology is the general area your question gets into and loop space narrows it down to a type of cosmic models that bounces.
Here is another sample search, more or less the same. I'm not sure about what the quote signs do.

http://inspirehep.net/search?ln=en&ln=en&p="quantum+cosmology:+loop+space"++and+d+2010&action_search=Search&sf=&so=d&rm=citation&rg=25&sc=0&of=hb

All these papers first appeared or were published in 2010. They all involve a bounce cosmology model----collapse causing rebound to big bang.

However in this case the collapse is of a whole prior universe, not merely a single black hole.
So you could call these papers "big bounce" papers. That's just an illustrative example of what InSpire can get you. You can change the date from 2010 to some other year. You can change the keyword in quotes---I'll tell you other keywords later.

You could call the black hole rebound scenario a "little bounce" because a black hole is very little compared with a whole universe. Even the ones in the center of some galaxies called "supermassive black holes" are very tiny and take in very little matter compared with a whole universe. So we could say there are two ideas here: big bounce and little bounce.
This doesn't mean one is right and the other wrong---they are just two different bounce ideas that come up in the professional research literature.

The popular book to get from the library is called "The Life of the Cosmos" by Lee Smolin.
It is about the little bounce idea-----universes resulting from a black hole collapse.
Here is the amazon page about the book:
https://www.amazon.com/dp/0195126645/?tag=pfamazon01-20
If the public library does not have it, tell them about it and see if they will order it to add to their science collection. It is written for general audience.
 
Last edited:
  • #8
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
  • #9
As a further illustration of how InSpire works, if you want to scan titles/summaries of BOTH quantum gravity and quantum cosmology, still within the loop approach, this search works:

http://inspirehep.net/search?ln=en&ln=en&p=d+2010+and+k+(quantum+gravity+or+quantum+cosmology)+and+loop+space&action_search=Search&sf=&so=d&rm=citation&rg=100&sc=0&of=hb

Again k means keyword but the search is broadened to k (quantum gravity or quantum cosmology) and loop space, so you get more hits.
Thank you for taking the time with the links, but, now I must humble myself in all viewer's eyes and admit the only link I might comprehend clearly enough to harvest any knowledge will be the one to amazon and the book written in layman's term " The Life of the Cosmos". The reason this may be the only link is I am under-educated and only posses a "Jethro Clampet" education, which means I only have half of my grade twelve, which, when calculated, translates to a real world grade 6,lol,lol. I have to be honest and say that when I post, anything I say or ask is born of pure curiosity that is fueled by "uneducated guesswork". For instance, I credit black-holes for maybe being the answer to the multiple universe concept and the "bubble" or "foam" description I have read and heard about. The reason I think this may be the answer is that it is the only one that make sense to me because black-holes spewing into universes which also have black-holes spewing into universes sounds a lot like bubbles or foam to me. There you have it . My "method of madness" and if I am wrong then it must already be proven wrong and therefore I am as stupid as I believe myself to be. What do I call my trek to the questions I ask and the answers I give myself? Fantasy? Madness? Stupidity? I have often wondered and am afraid of the answer. Peace Brothers and Sisters!!!!!
 
Last edited:
  • #10
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
...only posses a Jethro Clampet education, which means I only have half of my grade twelve, which, when calculated, translates to a real world grade 6,lol,lol...
Well you seem to me sensible, well-spoken, and of independent mind. I don't know how you strike others but that's my impression. Maybe we can come up with more stuff for you to look at that suits your requirements.

I wouldn't advise buying "The Life of the Cosmos" because it is a 1999 book that sold widely some years back. It should be in the library. And being over 10 years old it would be a bit out of date.

My personal view is that it is very important for someone like yourself to have alternative sources of information---something to look at and think about besides what you already get from television.

I wish some other people would come up with some ideas. I can't think what to suggest.
=======================

Maybe for the time being we can simply talk about Smolin's black hole bounce idea, that he develops in that 1999 book. It's rather interesting (although like any other new idea it might be wrong).

The starting point for all cosmology discussions is the 1915 theory of "GR" which describes how the shape of space (surveyed from within, not viewed from outside) interacts with matter and changes. A bunch of equations describing how geometry interacts with matter.

GR is known to be very close to right. But it can't be absolutely right because it suffers from singularities. (A technical word for failures in a manmade mathematical description.) In extreme situations its equations fail and don't give meaningful numbers.

So there is work in progress to modernize the GR equations so they will not fail.
(The "einstein-online" link in my signature might help you understand this.)

One of the approaches to modernizing GR is called "Loop quantum gravity" or "Loop gravity" for short, but specifics don't matter. there are actually a half dozen of various different approaches to modernizing GR.

When you modernize GR and, say, use the modernized theory to make a computer model of a collapse, it doesn't necessarily develop a failure and end there. It may bounce!

We don't know what Nature would actually do, but at least in some new theories (hoping to replace the old 1915 version of how geometry interacts with matter) collapse is not necessarily a dead end.

So Smolin took this idea and ran with it. He imagined that a universe could have "children" by its black holes. New universes which we do not see, budding off from black holes in our universe and expanding at breakneck speed. And he imagined that the children could by accident be slightly different from the parent.

the constants in physical laws might be jolted slightly during the bounce, so that physics (and therefore chemistry based on atomic physics) might be slightly different in the daughter from what it was in the mother.

And he reasons on from there. How a kind of evolution might occur based on selection for "reproductive success". How many black holes a universe makes depends in interesting ways on how well adjusted the physical constants are. You need some key physical mechanisms to produce, for starters, clouds of gas which then are able to condense to form stars. And certain chemical elements and molecules help radiate heat away allowing more condensation. And constants of particle physics can be either conducive or not conducive to eventually the star collapsing to a black hole (or getting stuck halfway and just making a neutron star).

So he reasons on and on, about a kind of "natural selection" favoring universes which are able to have a lot of children and live a long time over universes with less fortunate physics. As I recall it gets to be a rather interesting story.

It is primarily just conjecture except that one can ask whether the constants of physics (and chemistry) in our universe are actually adjusted so as to promote making a lot of black holes. So there is actually a testable hypothesis here. So it is, in a sense, science, not merely fantasy.

But it could well be wrong. Some people think that it has already been shown that the physics constants in our universe are NOT ideal for making a lot of black holes, which would suggest that this kind of natural selection evolution has NOT been at work amongst our ancestor universes. I think this is still undecided, and it remains an interesting idea.

The fact remains that the bulk of research on bounce cosmologies does not involve black holes. At the present time they are mostly studying models where a whole universe collapses to produce a bounce and an expansion (like what we see.) That is actually simpler to study, and simpler to simulate in the computer.

Maybe when they have studied whole universe bounce ("big bounce") for a while they will again return to the idea of black hole bounce. Smolin's idea might be revived. But it's hard to foresee where research will go.
 
Last edited:
  • #11
Might I liken the "less fortunate physics universe" to these universes being "deformed" or having "deformities"?? Peace!!!!
 
Last edited:
  • #12
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
Korben, it sounds to me like you are ADAPTING Smolin's story of natural selection to fit your own imagination. That's fine. But I can't guide you in choice of words or images.

It's actually a rich fantastic story (baby universes budding off and growing up and some of them out-performing their parents etc etc---the laws of physics themselves evolving because of the very slow gradual change of the constants, a tiny fraction of a percent each generation either in a good direction or a bad).

But basically I am a *follower of current research* and a watcher of the current action from the sideline. I am not an *imagination feaster*. I want to focus what brains I've got on the current research action. Not so much is happening in black-hole bounce, right now. Much more is happening in the BIG bounce department. All that stuff that the InSpire search turns up, that I showed you.

That is easier to study and eventually to TEST BY OBSERVATION. It is the straight "crunch-bang" picture. the equations work. It would have noticeable effects on the ancient light (microwave) background, assuming some refinements in the instruments are made to pick it up. You can program the equations into the computer and simulate the bounce process and study it. So the situation is all ready to do regular science with.

Smolin's "fertile universe" picture is not so well disposed to do science with. No "multiverse" scenario really is. His is easier to check than most other of those scenarios, but still not science-ready enough.

Some people call it the "fecund" universe. fecund is just another word for fertile. smolin calls it "cosmic natural selection"

You can try google with keywords like cosmic natural selection, and fecund universe.
If you are interested try it and see what you can get online. But also be sure you put a hold on the book at the public library. If your local does not have it, you can probably get it through INTERLIBRARY LOAN. Libraries are connected in a network.
 
  • #13
Marcus, you are very helpful and encouraging!! All the info is more than enough.This gives me something to look forward to. Perhaps I will learn!!! Thank you kindly!!!! Peace!!!!!
 
Last edited:
  • #14
472
9
Hi Marcus , I have a couple of questions about CNS.

As I recall there was a claim that CNS impllied a certain mass limit for neutorn stars and this was observed to be breached hence CNS was falsified.

However I cant help but be suspicisous of the idea that an evolutionary theory can make such predictions. Biological evoluiton can only predict what we find in the past comapred to the present, i.e simpler preceeds more complex, not what the world chould look like given an evolutionary process. So why Should CNS be different?
Does Smolin still push CNS or did I remember the neutron star predictions wrong?

As I understand the early universe, you run the evolution of the unvierse backwards and in standrard GR you get a singualrity , but in LQC you get a bounce as the density cant be increased for ever. But is the idea that we bounced form a previous universe rather than the black hole bounce as Smolin suggested just an assumption or is there a more pressing reason to chose between the two?
 
Last edited:
  • #15
222
11
Not so much is happening in black-hole bounce, right now. Much more is happening in the BIG bounce department.
I have trouble comprehending the big bounce because of the difference in geometry between the idea of the Big Bang happening everywhere, with no centre, and a BH having geometric position.
 
  • #16
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
I have trouble comprehending the big bounce because of the difference in geometry between the idea of the Big Bang happening everywhere, with no centre, and a BH having geometric position.
Narrator, I don't understand your comment. What are normally called big bounce scenarios do not involve BH in any essential way.

There are two broad types of bounce cosmologies. In the one Smolin has written some interesting stuff about you have a BH collapse. Google "fecund universe". You wouldn't call that big bounce, you might call it "black hole bounce"

In the other type, which is what most of the work focuses on nowadays, a whole universe collapses. They sometimes call that the "big bounce".
=================================

Let me know if you are focusing your attention on the "black hole bounce" thing rather than big bounce. In that case I would tend to agree if you find it difficult to understand topologically. Indeed the idea could turn out to be invalid. That may be one reason it is not being researched nowadays.
Researcher's attention is much more on the other alternative---the one called big bounce. There the topology is straightforward.
 
  • #17
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
...Does Smolin still push CNS or did I remember the neutron star predictions wrong?
...
I don't want to sound like an authority on this when I'm just saying how I size it up. I think CNS is dead. I don't hear Smolin still talking about it.
(except every now and then recapping very quietly, and not saying anything new).
His research focus has been completely on other stuff for the past three or four years.

That would, I guess, be for three reasons.

1. A prime motive for CNS after around 2004-2008 was to counter the non-empirical multiverse fad (pushed by string theorists in particular, like Susskind).
CNS is unique among Multiverse pictures in that it is directly FALSIFIABLE by observation. Theories ought to be that. So he was showing up the string landscape multiverse promoters for being into self-indulgent fantasy. His multiverse was testable. It continued in the Baconian empirical tradition. Theirs was not and did not.

But in 2008 the organizers of Strings 2008 excluded all landscape/multiverse talks from the conference. The community showed it could be self-correcting and didn't need to be showed up. Rome 2009 just had a token multiverse representation (really a post mortem talk). Texas 2010 nothing significant either. Uppsala 2011 kept it outside the doors, as a PUBLIC LECTURE by Brian Greene. No conference talks about it, at least that I recall.

I think the string landscape/multiverse/multibubbleinflation story is unempirical mind-candy and the Strings 2008-2011 conference organizers ran a tight ship in that regard. This is to their credit. The proper use of stuff like that is TV series and selling popular books/lectures like by Greene and Hawking.

So after 2008 Smolin had no serious motive to promote CNS. In-house the nonempirical multiverse fad was over and it was persisting only outside in the commercial realm and public mind.

2. Also CNS was at least nominally falsified by the too-big neutron star mass. You are right. But if there had been a strong motivation somebody might have found a work-around to that. One falsification should not always be decisive.

3. Also I have trouble imagining this topologically. The standard spatial-finite universe is an expanding S3----like the balloon but of one higher dimension with no inside or outside, all existence all space and matter is concentrated in that 3D continuum, no surroundings. Expansion just means that distances within the continuum increase

How do you picture a black hole bounce producing an expanding S3?
====================

Maybe it's possible to imagine after all. Think in one lower dimension. The familiar 2D balloon surface again, expanding S2.

The balloon might bud off a little balloon. At first a bump, which enlarges and forms a neck, which then pinches off. The new little balloon separates and expands on its own. They have no surroundings that they expand "into" so there is no problem of colliding with the parent.

OK maybe 3. is not a good objection. Maybe it is imaginable. But 1. and 2. are enough to stall the idea, at least put it on hold for a while.
 
Last edited:
  • #18
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
...
As I understand the early universe, you run the evolution of the unvierse backwards and in standrard GR you get a singularity , but in LQC you get a bounce as the density cant be increased for ever. But is the idea that we bounced from a previous universe rather than the black hole bounce as Smolin suggested just an assumption or is there a more pressing reason to chose between the two?
As I see it the Smolin idea is dead or at least on long-term hold. So it is confusing to have it in the above paragraph. To make a clear question that I can try to think about, I will edit it out and get something to concentrate on without unnecessary distraction:

==simplified quote==
As I understand the early universe, you run the evolution of the unvierse backwards and in standrard GR you get a singularity , but in LQC you get a bounce as the density cant be increased for ever. But is the idea that we bounced from a previous universe...just an assumption?
==endquote==

The LQC bounce is a testable scientific hypothesis because you can model it either in computer or with equations and it leaves an imprint on the early universe that one can hope to observe in the ancient light.

The thing to focus on is a set of equations describing the beginning of expansion (that don't break down and suffer a singularity).

It happens that this set of equations give you a prior contracting universe. What is more important though, scientifically speaking, is that they tell you about a footprint in the ancient light that you can look for either in the ESA-Planck mission data or in some successor mission's data.

This footprint business is extremely interesting and has attracted the attention of researchers.

What they are doing now is studying all the variants of the LQC bounce they can think of, including ones that are non-isotropic. In effect "oblong" rather than "round". So to speak asymmetric collapse---crunching in some directions faster than others. One of the variants they are studying is called "Mixmaster" another is "Kasner" and others are just called "Bianchi" with various numbers like Bianchi I, II, IX.

I would say that the prior collapsing universe is just a kind of side-effect of the equations and that what the guys need to do and are doing is to consider all the possible solutions of the equations and all the ways the LQC bounce could have occurred---all the different "Bianchi's" and "Mixmasters". And they need to derive footprints to look for in the ancient light to look for. As they have already to some extent done.

And then people have to launch CMB instruments like WMAP and Planck, but better. And then they will have a better idea if that set of equations is right or not.
Maybe they will NOT find the indicated footprint, and that will DISPROVE the LQC bounce picture.

In all this the prior collapsing universe is not an assumption it is a consequence that you derive from the set of equations that people are studying and will be testing with future space missions (I expect.)

It's a question of what you concentrate on. I concentrate on the footprint, which is gradually being worked out by the researchers, and dismiss the prior contracting universe as an unimportant side-effect of the model to be tested.

You can take a different attitude and say but what about all those poor aliens screaming as their planets plunge into a fiery collapse! But I would say that is jumping the gun. It is not yet time to worry about that feature of the model. One has to test the bounce first. Did a LQC-type bounce occur? Does that set of equations fit the data? Only after we see a fit (which we might not, we might see a misfit) would it be time to worry about the screaming aliens in their doomed prior world.
 
  • #19
222
11
Narrator, I don't understand your comment. What are normally called big bounce scenarios do not involve BH in any essential way.

There are two broad types of bounce cosmologies. In the one Smolin has written some interesting stuff about you have a BH collapse. Google "fecund universe". You wouldn't call that big bounce, you might call it "black hole bounce"

In the other type, which is what most of the work focuses on nowadays, a whole universe collapses. They sometimes call that the "big bounce".
=================================

Let me know if you are focusing your attention on the "black hole bounce" thing rather than big bounce. In that case I would tend to agree if you find it difficult to understand topologically. Indeed the idea could turn out to be invalid. That may be one reason it is not being researched nowadays.
Researcher's attention is much more on the other alternative---the one called big bounce. There the topology is straightforward.
This is where my ignorance shows up ;)

In a big bounce scenario, I've always pictured it as being like black hole creation, but had that topographical difficulty. I guess in some respects it would be similar - with matter compression etc, but I guess it would be very different, owing to the addition of DM, DE and entropy. And I imagine a BH is finite where a universe is not (given the more accepted model), leading to space-time issues that a BH may not be so affected by.

Not being a scientist leaves me dealing with concepts, with my mind broadening slowly as I learn things here.
 
  • #20
472
9
"I think the string landscape/multiverse/multibubbleinflation story is unempirical mind-candy and the Strings 2008-2011 conference organizers ran a tight ship in that regard. This is to their credit. The proper use of stuff like that is TV series and selling popular books/lectures like by Greene and Hawking."

However at the recent PI symposium on the early universe there were several talk on this topic:
http://www.perimeterinstitute.ca/Events/Challenges_for_Early_Universe_Cosmology/Abstracts/ [Broken]

Have you see any more reaction or care to comment on this paper?
http://arxiv.org/abs/1012.1995

It proposes a possible way to get an emeprical verification of the multiverse.
 
Last edited by a moderator:
  • #21
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
Phil, this is something having to do with POV that we don't have to argue about. We just have to wait and see how the professional consensus and conference real-politik sorts the issue out.
Science (as you well understand1) is partly a social thing based on a self-selecting self-defining community and ultimately rests not purely on logic but on arguments dogfights and judgement calls.

I can tell you my POV, but I should say that it ultimately matters only to me. I think that as a rule the theory being tested is the one at risk namely the one that could be falsified by the experiment.

If you look and do not see evidence of bubbles having bumped that does not falsify bubbles. The bubble-man can just say that all it means is they are farther apart and bumping rarely happens. The theory of bubbles has an infinite amount of "give".

So from my POV (science is empirical, scientific theories are testable) it doesn't qualify as a scientific theory.

=======================

I would say that what those 1012.1995 people were testing were much older and more important hypotheses. The cosmological principle (the uniformity idea---the singleness and sameness of the U).
Milne stated this, I think around 1930s, and attributed it to Einstein. It's the basis of the usual cosmic models. The idea is that there is no boundary. When you model the U you don't have to include the extra complication of a boundaries and discontinuities which would be an awful headache. It's all one, or behaves as if it is all one----on average uniform at large scales. If you could go out to edge of what we can see and look around it would look about the same.

What those people were actually testing was the venerable assumption of singleness and sameness. If they had found bruises from bumps it would have nullified that. That was what was AT RISK, so that was what was being tested.

It has been tested many times. People are always looking for signs of non-uniformity. A recent example was the buzz about the "dark flow", which somebody thought for a while that he was seeing. Another was the "great void" that somebody thought was improbable. It turned out that voids can happen as stuff falls together into strands, and the observed void was not so great after all and the buzz died. There were other voids it it was not so improbable after all.
 
  • #22
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
As I see it the admirable thing about Smolin's idea was that it was AT RISK, because it had the selection-for-reproductive-success feature.

It envisaged a reproductive mechanism (BH) which made it overwhelmingly likely that our physics constants are better (than their immediate neighbors) for producing BHs.
The moment you see that is not the case, that our constants are not finetuned for BH abundance, Smolin's idea is out the window.

It made an actual prediction. The telescope people could check it. So I consider Smolin's idea to be to his everlasting credit---it was a beautiful and honorable scientific theory.

Bubbles (which might bump if they happen to be close enough together) I do not so regard.

Basically this is just our personal POVs. The real thing is how it plays out in the community.
The most interesting thing at the PI conference, I thought, was what Elena Magliaro said to Neil Turok, from the audience, right after his talk. I love her. She is a smart gutsy woman.
 
  • #23
472
9
I am very sympthateic to the idea of falsifiability as the benchmark for science . But now I have some doubts that may you can redress. I think it was Poppers idea that theories are never proven , they are only failed to be falsified.
However take the idea that there is life elsewhere in the universe. As far I can see ,this for all practical purposes is unfalsifiable. How could we do a test that would falsify such an idea?
Yet if we find one clear example of life on another planetary body the idea will be confirmed annd hence we should accept it.
Hence falsifiability whilst being a very desirable property of a theory is not the only way to gain confidence in it. We can actaully verify it.
What do you think?
Im tentative on these thoughts and very much value your opinions so would love to hear you feedback.
 
  • #24
472
9
Basically this is just our personal POVs. The real thing is how it plays out in the community.
The most interesting thing at the PI conference, I thought, was what Elena Magliaro said to Neil Turok, from the audience, right after his talk. I love her. She is a smart gutsy woman.[/QUOTE]


I remember someone challenging him (Turok) with Ashketars/Sloans result that showed inflation was not so imporbable in LQC and he said their reuslts just had to be wrong. Very dismissive of him I thought. If he thinks they are wrong he should show it, not just state it. Was that her? Is that what you are referring to?
 
  • #25
marcus
Science Advisor
Gold Member
Dearly Missed
24,738
785
Basically this is just our personal POVs. The real thing is how it plays out in the community.
The most interesting thing at the PI conference, I thought, was what Elena Magliaro said to Neil Turok, from the audience, right after his talk. I love her. She is a smart gutsy woman.
==endquote==

I remember someone challenging him (Turok) with Ashketars/Sloans result that showed inflation was not so imporbable in LQC and he said their reuslts just had to be wrong. Very dismissive of him I thought. If he thinks they are wrong he should show it, not just state it. Was that her? Is that what you are referring to?
Definitely. Neil Turok should be ashamed of his inadequate response to her comment.

Elena Magliaro gave a talk at PI about that time. The video is on PIRSA. Her husband is Claudio Perini, who occasionally visits PF and reads our threads. The two of them have co-authored some pretty good QG papers.

I didn't realize until several days later that it was Magliaro who made the comment. I thought it was calm, cogent, and much-called-for. I was wondering and later asked a friend who it was that spoke up.

I thought that PI conference was debased currency---a desperate ploy on Turok's part to keep attention on his pet brane-clash idea.

His selling-point, actually a rather involved argument, is undercut by anything that makes inflation robust (as it is in Ashtekar's picture).

He argues that since adequate inflation is highly improbable and requires finely adjusted parameters (i.e. not robust) we are obliged to consider some rather elaborate curious alternatives like clashing branes. (Interest in which has faded considerably.)
So his position is rather vulnerable and will not survive scrutiny. He must steadfastly ignore any active cosmology program where inflation is robust.

Human nature :biggrin: Brilliant politically adroit people are just like the rest of us (in a good many ways.)
 

Related Threads on Our ever expanding universe?

  • Last Post
Replies
1
Views
2K
Replies
4
Views
3K
Replies
18
Views
950
Replies
76
Views
11K
Replies
51
Views
3K
Replies
6
Views
752
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
13
Views
4K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
6
Views
2K
Top