What is the Cosmological Natural Selection theory?

In summary, Cosmological Natural Selection is a testable idea for explaining why the constants in physics and cosmology----the parameters of the standard models used in the two fields----have the numerical values they do.
  • #1
marcus
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Cosmological Natural Selection is a testable idea for explaining why the constants in physics and cosmology----the parameters of the standard models used in the two fields----have the numerical values they do.

I expect it's important enough so that it deserves a more transparent thread heading than "Cns" which is the title of the thread Chronos already started.

CNS has been proposed as a scientific alternative to "Anthropic" views, according to which the values of the constants do not require a mechanism to explain them because if several of the key numbers were substantially larger or smaller we would not be here to observe it!

Contrary to "Anthropic" (non?)explanations, the CNS idea offers an evolutionary mechanism by which the constants may have converged on their observed values, in a fashion which has nothing to do with life or consciousness. Nothing to do, that is, except having incidentally provided the conditions needed for life as we know it as kind of side effect, or byproduct.

And the idea may be wrong, which, curiously enough, is a virtue. CNS seems able to generate predictions ruling out certain observations or experimental outcomes in the future, which, if they WERE seen, would refute CNS. this "falsifiability" is the hallmark of a scientific theory---it is predictive in the sense that there are some outcomes of future experiments which it cannot accommodate. If a theory is mushy enough to accommodate any conceivable outcome of future experiments intended to test it, then it has no predictive value. (Try to imagine performing an experiment and obtaining a result that is incompatible with the existence of conscious life! :smile:) By contrast, CNS seems to to be predictive, hence part of empirical science instead of, say, philosophy or religion.

I'm intending this to be an informational thread about CNS, so for starters here is a short reading list borrowed from the LQG link-basket
https://www.physicsforums.com/showthread.php?p=527991#post527991

1.these two papers, and the references therein, discuss the removal of the classical BB ex-singularity in a range of cases that has gradually extended the generality of Bojowald's initial 2001 result.

http://arxiv.org/abs/gr-qc/0402053
Loop Quantum Cosmology: Recent Progress
Martin Bojowald
17 pages, 2 figures, Plenary talk at ICGC 2004

"Aspects of the full theory of loop quantum gravity can be studied in a simpler context by reducing to symmetric models like cosmological ones. This leads to several applications where loop effects play a significant role when one is sensitive to the quantum regime. As a consequence, the structure of and the approach to classical singularities are very different from general relativity: The quantum theory is free of singularities, and there are new phenomenological scenarios for the evolution of the very early universe including inflation. We give an overview of the main effects, focussing on recent results obtained by several different groups."

http://arxiv.org/abs/gr-qc/0503020
The Early Universe in Loop Quantum Cosmology
Martin Bojowald
10 pages, 3 figures, plenary talk at VI Mexican School on Gravitation and Mathematical Physics, Nov 21-27, 2004

"Loop quantum cosmology applies techniques derived for a background independent quantization of general relativity to cosmological situations and draws conclusions for the very early universe. Direct implications for the singularity problem as well as phenomenology in the context of inflation or bouncing universes result, which will be reviewed here. The discussion focuses on recent new results for structure formation and generalizations of the methods."

2. these papers, and references therein, go towards understanding the BH ex-singularity and showing that it evolves into the BB ex-singularity:

http://arxiv.org/abs/gr-qc/0503041
A black hole mass threshold from non-singular quantum gravitational collapse
Martin Bojowald, Rituparno Goswami, Roy Maartens, Parampreet Singh
4 pages, 3 figures

"Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a simple toy model of a collapsing homogeneous scalar field. We show that non-perturbative semi-classical effects of Loop Quantum Gravity cause a bounce and remove the classical black hole singularity. Furthermore, we find a critical threshold scale, below which no horizon forms -- quantum gravity may exclude very small astrophysical black holes."

http://arxiv.org/abs/gr-qc/0504043
Quantum Gravitational Collapse
Leonardo Modesto
13 pages

"We apply the recent results in Loop Quantum Cosmology and in the resolution of Black Hole singularity to the gravitational collapse of a star. We study the dynamic of the space time in the interior of the Schwarzschild radius. In particular in our simple model we obtain the evolution of the matter inside the star and of the gravity outside the region where the matter is present. The boundary condition identify an unique time inside and outside the region where the matter is present. We consider a star during the collapse in the particular case in which inside the collapsing star we take null pressure, homogeneity and isotropy. The space-time outside the matter is homogeneous and anisotropic. We show that the space time is singularity free and that we can extend dynamically the space-time beyond the classical singularity."

3. if the models of BH collapse and BB expansion can be joined in theory then one can take seriously the CNS (cosm. nat. selection) hypothesis as a way of understanding why the basic constants in the Standard Models are what they are. The CNS theory can be tested empirically by observation and experiment. This paper discusses CNS:

http://arxiv.org/abs/hep-th/0407213
Scientific alternatives to the anthropic principle
Lee Smolin
for "Universe or Multiverse", ed. by Bernard Carr et. al., to be published by Cambridge University Press.

"It is explained in detail why the Anthropic Principle (AP) cannot yield any falsifiable predictions, and therefore cannot be a part of science. Cases which have been claimed as successful predictions from the AP are shown to be not that. Either they are uncontroversial applications of selection principles in one universe (as in Dicke's argument), or the predictions made do not actually logically depend on any assumption about life or intelligence, but instead depend only on arguments from observed facts (as in the case of arguments by Hoyle and Weinberg). The Principle of Mediocrity is also examined and shown to be unreliable, as arguments for factually true conclusions can easily be modified to lead to false conclusions by reasonable changes in the specification of the ensemble in which we are assumed to be typical.
We show however that it is still possible to make falsifiable predictions from theories of multiverses, if the ensemble predicted has certain properties specified here. An example of such a falsifiable multiverse theory is cosmological natural selection. It is reviewed here and it is argued that the theory remains unfalsified. But it is very vulnerable to falsification by current observations, which shows that it is a scientific theory.
The consequences for recent discussions of the AP in the context of string theory are discussed."
 
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  • #2
A few points.

1. Publishing an article in an Intelligent Design showpiece book, even if it says that CNS is better than AP, is a pretty counterproductive activity.

2. Smolin's article claims to be based on a conjecture by J.A. Wheeler that all the fundamental constants change when black holes happen. Where does that come from and what does he have to back it up?

3. Falsifiabilty does not a scientific theory make. A valid scientific theory needs to be an empirically motivated explanation for observed phenomena which explains the data without unnecessary elaboration or extrapolation from known facts.

I can hypothesize that fairies create stars in nebula by following a formula combining various proportions of atomic gases, that the fairies are not themselves luminous and contribute immaterially to the total mass of the nebula making them hard to detect by gravity, that they are corporal and as easy to observe as a ferret, and that they move a speeds less than 1% of the speed of light in a vaccum. I can further hypothesize that fairies particularly like galactic clusters and that their presence accounts for the exceptionally high dark matter content of such structures. I can further show, that the fairie theory makes cosmological inflation unnecessary because eternally existent fairies could have through intentional action achieved events that blind graviational forces would not. I could then recast all of stellar evolution as a theory of fairie behavior.

We haven't gotten close enough to any nebula to falisfy that theory. But, certainly it could be falisfied, in principle anyway, by going to a nebula and looking for them where they are ubiquitous. But, I think you'd agree that this is still not a scientific theory.

Scientists have never observed fairies, no experiement has ever predicted the existence of a fairie. Likewise, science has never observed a change in a physical constant and no experiment has ever indicated a change in a physical constant. Maybe a few French scientists who've had too much abisinthe have thought about the fairie idea (this is called Green Fairie Theory) and even played it out for a while without finding any obvious objections, but certainly no one is rushing to show how fairie theory is falisfiable, while AP is not, in an Intelligent Design anthology.

4. Arguing from the credibility of the author doesn't count for much either.

Newton is one of the most renounced scientists for hundreds of years either side of his birthdate. His theories are still taught in college physics and the foundations of his ideas are still visible even in modern physics elaborations of those ideas. But, he also spent huge amounts of time working on heretical theology and alchemy. Even the best scientists get bad ideas from time to time.
 
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  • #3
Another point.
marcus said:
Contrary to "Anthropic" (non?)explanations, the CNS idea offers an evolutionary mechanism by which the constants may have converged on their observed values, in a fashion which has nothing to do with life or consciousness. Nothing to do, that is, except having incidentally provided the conditions needed for life as we know it as kind of side effect, or byproduct.
CNS is not contrary to anthropic explanations, it is a possible anthropic explanation! If we ask the question: "Why have physical constants the values they have?" CNS suggests the answer: "Because those constants maximise the production of black holes in any given universe after a sufficient number of 'cosmic' iterations. "

The AP evokes a set of possible and alternative explanations:
1. It is a brute fact, a 'fluke'.
2. It is a selection effect. There is a multiverse and we are in this universe because we can be in no other.
3.There is an unspecified mechanism that determines the constants to be so.
4. Observers today collapse the wave function of the entire universe so that it allows the existence of observers today; this may be one possible mechanism required by 3.
5. It is the product of design.

CNS is also one of the possible mechanisms required by response 3.

Finally, is not the fact that this set of values "incidentally provided the conditions needed for life" rather a coincidence, indeed an anthropic coincidence?

Garth
 
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  • #4
I agree with Garth. CNS is a subtle version of an AP argument.
 
  • #5
ohwilleke said:
I agree with Garth. CNS is a subtle version of an AP argument.

I don't agree, Ohwilleke, and do not see CNS as a version of AP. However since Garth says CNS belongs to his AP version #3, let us look at it.
 
  • #6
Garth said:
Another point.

CNS is not contrary to anthropic explanations, it is a possible anthropic explanation! If we ask the question: "Why have physical constants the values they have?" ...

The AP evokes a set of possible and alternative explanations:
...
3.There is an unspecified mechanism that determines the constants to be so.
...

CNS is also one of the possible mechanisms required by response 3.
...

Garth alternative #3 is not the AP as commonly understood.

for centuries the goal of physics theory has been to find mechanisms determining the features of the world (the distances and periods of planets, the wavelengths of the hydrogen spectrum) and to reduce the number of constants

a longstanding goal of string theory was to reduce the parameters down to one, to derive the other constants from the string constant.

theorists have traditionally asked "why have the constant proportions of nature the values they do?" and have traditionally searched for
"unspecified mechanisms that determine" the proportions of nature to be as they are.

this goes back a long time and has nothing to do with the "anthropic" (lack of) principles, which distract people from seeking mechanisms determining the constants by offering a phony explanation (that the constants have to be what they are because of something to do with conscious life)

so Garth #3 doesn't cut the mustard and I remain skeptical of his effort to include
CNS under the AP tent.
 
  • #7
Garth said:
Finally, is not the fact that this set of values "incidentally provided the conditions needed for life" rather a coincidence, indeed an anthropic coincidence?

Dear Garth, if you want to take it as a proof that God loves us because the constants of nature, as optimized for black hole production, accidentally allow carbon-chemistry and life, that is FINE and I will applaud you as a man of reverence and devout spirituality.

what I care about is that people should seek mechanistic explanations for why the laws of nature and the proportions built into them (the dimensionless parameters) are as they are

I shall hope that people will always be dissatisfied with the phony explanation that the values of the constants somehow reflect our existence

and I will be happy with whatever theological spin anyone wants to put on the models being tested.
 
  • #8
I think selection effects is a very powerful argument. All that really says is, at some level, there is a deeper reason why things [like fundamental concepts] are what they are. To claim otherwise is to say 'chit happens'. And that's not very satisfying, much less scientific. The more important question [to a scientist] becomes what is the deeper reason? The anthropic principle is a pretty weak candidate compared to CNS. The universe was around long before us, or any other probable spectators. It reminds me of the coach joke

Reporter: "Folks, I'm here with coach [insert favorite] on tonite's show. Coach, what would you say is the most amazing thing you've seen in your illustrious career?"

Coach: "the thermos bottle"

Reporter: "What do you mean?"

Coach: "Put something hot in it, it stays hot. Put something cold in it, it stays cold."

Reporter: "What is so amazing about that?"

Coach: "How do it know?"
 
  • #9
Marcus, I have told you about my ferrethropic model and my extreme adversion to the logical extension to the earmitethropic model. I did this in jest, but I am very serious. The idea that anyone can point to the existence of ANY object or ANY lifeform and say "the existence of X is proof that all the cosmological parameters must be as they are" is pretty silly. Actually it's worse than silly, but I'm trying to be nice.

Let's get pretty basic. If the existence of X and Y arises out of conditions of the Universe A, we might posit that the conditions of Universe A are necessary for the existence of X and Y. If someone tries to claim that the observation of the present-day existence of X and Y places prior constraints on the conditions of Universe A, I've got to ask "what are you thinking?" Humans have existed in this universe for less than an eyeblink in time, and for someone to postulate that the Universe is fine-tuned to produce us is the height of stupidity. If you look at Lee's paper, I think he's got an admirable tongue-in-cheek attitude that challenges Lenny to come up with a viable explanation for the anthropic principle that shows how the Universe must be fine-tuned to produce weak short-lived bags of mobile protein instead of black holes.

I think Lee is spending just a bit of his scientific "capital" to set the field for the much more important discussion regarding the logical (or not!) extensions that the AP people are making regarding the relationships between basic constants and the "coincidence" that we are here.

This speaks to a really basic problem of the AP and of intelligent design: "We are here and we see our universe. We think that X, Y, and Z are true, based on what we see. If X, Y, and Z were not true, the universe would be different, and therefore we would not exist. Therefore, we exist because some underlying design made sure that X, Y, and Z were in place, which allows us to exist here and now." I just love it when the entire cosmos conspires to make me exist! It smells like victory!
 
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  • #10
turbo-1 said:
This speaks to a really basic problem of the AP and of intelligent design: "We are here and we see our universe. We think that X, Y, and Z are true, based on what we see. If X, Y, and Z were not true, the universe would be different, and therefore we would not exist. Therefore, we exist because some underlying design made sure that X, Y, and Z were in place, which allows us to exist here and now." I just love it when the entire cosmos conspires to make me exist! It smells like victory!
Maybe it clarifies things to think in terms of entropy. Obviously, people represent a highly improbable construction since it is more likely that things dissipate. Perhaps the universe that must be chosen from the landscape is the one that allows for such complexities to arise. It may not be human, per se, that are required but constructions that represent a reduction in entropy to balance otherwise too much dissipation. If the physical constants were changed slightly, could complex structure even arise in such a universe? Perhaps the constants are chosen to at least allow for maximum decreases in entropy if the need should arise?
 
  • #11
Mike2 said:
Maybe it clarifies things to think in terms of entropy. ...

you have put your finger on a significant issue for the CNS picture of how the universe evolves

right after the big bang (to the extent that one can see a thermodynamic state where entropy is defineable and makes sense) the entropy would seem to be very low

at least from our point of view looking back at it in our past

but prior the big bang, if there was a black hole collapse (as per CNS picture) then it would seem to have very high entropy, at least from the perspective of people outside the hole looking at the event horizon. We normally think of black holes in our universe as having very high entropy.


if you can picture a timeline or worldline running from those observers (one of them jumps in) down thru the hole and the big bang and thence to us (which I cant. I don't think that is a valid timeline) but if you can picture keeping track of the entropy along that line (which I see problems with) then you find yourself going from seeing a high entropy state (looking at the BH) to a very low entropy state (looking at the fresh universe right after BB). that is supposed not to happen, entropy is only supposed to increase.

I think the best way to handle this is to clarify in each case who the observer is. Like Crosson indicated, entropy is defined relative to an observer (the log of the number of different states that look the same TO THAT OBSERVER according to what variables that observer can measure, be it pressure volume temperature or whatever.

the Crosson post I mean is this one:
https://www.physicsforums.com/showthread.php?p=540380#post540380
it was in response to a question you raised about entropy in a thread you started, Mike
 
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  • #12
Good point, marcus. Could the bounce in a gravitational collapse result in a frame dependent measure of entropy? An observer outside the event horizon would measure a huge amount of entropy, while an observer inside the event horizon would measure almost zero entropy. It would make sense as an extension of the equivalency principle.
 
  • #13
Chronos said:
... It would make sense as an extension of the equivalency principle.

I am not quite clear on relating entropy and general relativity (maybe that is an understatement, maybe i am grossly unclear about it:smile:) but I does seem interesting.

oh yes, the OBSERVER. entropy seems to be rather much in the eyes of the beholder doesn't it?---what level of detail he sees, what he coarse-grains or doesnt.
 
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  • #14
marcus said:
Garth alternative #3 is not the AP as commonly understood.

for centuries the goal of physics theory has been to find mechanisms determining the features of the world (the distances and periods of planets, the wavelengths of the hydrogen spectrum) and to reduce the number of constants

a longstanding goal of string theory was to reduce the parameters down to one, to derive the other constants from the string constant.

theorists have traditionally asked "why have the constant proportions of nature the values they do?" and have traditionally searched for
"unspecified mechanisms that determine" the proportions of nature to be as they are.

this goes back a long time and has nothing to do with the "anthropic" (lack of) principles, which distract people from seeking mechanisms determining the constants by offering a phony explanation (that the constants have to be what they are because of something to do with conscious life)

so Garth #3 doesn't cut the mustard and I remain skeptical of his effort to include
CNS under the AP tent.

I'm sorry I disagree. My option 3."There is an unspecified mechanism that determines the constants to be so." is the Strong Anthropic Principle. "The Universe must have those properties that allow life to develop within it at some stage of its history." (Barrow & Tipler - The Anthropic Cosmological Principle)

Another way of seeing this is to say that if there were a multiverse then every universe would be propitious for life, at some stage, out of logical necessity.

The task would be then to discover what that logical necessity is, i.e. what is the mechanism, in the venerable tradition: "for centuries the goal of physics theory has been to find mechanisms determining the features of the world".

Such a search and discovery would have no bearing on the question of belief in a 'Creator' or 'Design', which would be an interpretation on the facts, just as is non-belief in the same.
"I want to know how God created this world. I am not interested in this or that phenomenon, in the spectrum of this or that element. I want to know His thoughts; the rest are details." (A.E.)

A theist belief would simply be saying that mechanism is "God's way of doing it."

Garth
 
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  • #15
You seem to me to have made a logical error, Garth. Your post which I quoted was:

Garth said:
Another point.

CNS is not contrary to anthropic explanations, it is a possible anthropic explanation! If we ask the question: "Why have physical constants the values they have?" CNS suggests the answer: "Because those constants maximise the production of black holes in any given universe after a sufficient number of 'cosmic' iterations. "

The AP evokes a set of possible and alternative explanations:
1. It is a brute fact, a 'fluke'.
2. It is a selection effect. There is a multiverse and we are in this universe because we can be in no other.
3.There is an unspecified mechanism that determines the constants to be so.
4. Observers today collapse the wave function of the entire universe so that it allows the existence of observers today; this may be one possible mechanism required by 3.
5. It is the product of design.

CNS is also one of the possible mechanisms required by response 3.
...

Since you said CNS comes under heading 3, I extracted out

..."Why have physical constants the values they have?" ...

The AP evokes a set of possible and alternative explanations:
...
3.There is an unspecified mechanism that determines the constants to be so.
...
CNS is also one of the possible mechanisms required by response 3.
So far the argumentation does not involve life. CNS is a possible mechanism that determines the values of the constants---OK, so far you haven't dragged life in, CNS is determining some numerical values.

Now you surprise us all and pretend that your alternative 3. (which you stated without reference to life) was meant to be the Anthropic Principle all along.

---quote---
My option 3."There is an unspecified mechanism that determines the constants to be so." is the Strong Anthropic Principle.
---end quote---

Well it simply is not. "To be so" in your earlier post is a shorthand for "to have the values they have".

So it seems to me you are weaseling, or "zig-zagging". You say something, and then you pretend (or mistakenly act as if) you said something different.
Zig-zagging can make for a tedious conversation.

Also I am not sure what you mean by "unspecified", if you want CNS to be included. Granted that the details of the hypothesized connection between BH and BB remain to be worked out (and may indeed fail to work and be rejected!) is a specific mechanism that works in a specified way to determine some numbers. Since it is neither fully specified nor fully unspecified, I suggest that it may be tendentious to include the word "unspecified". So I would put your #3 this way:

"There is a mechanism that determines the constants to have the values they have."

This is NOT the Strong Anthropic Principle. CNS treats life as an epiphenomenon (essentially irrelevant side effect, byproduct) and offers to explain the values of the constants by some mechanism without reference to life. Only by zig-zagging can one blur the distinction between CNS and SAP.

I think I will see how it looks to spell "zig-zag" with a smilie :

:zzz:ig- :zzz:ag

hey cool :cool: :-p it works, not a bad way to spell it!
 
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  • #16
Just to be clear, CNS, of course, doesn't flow from the existence of life. But, I think it is fair to call it an AP like theory, because the type of reasoning is similar. Instead of arguing that the universe has the constants it does because conditions life exist, it argues that the universe has the constants it does because things like the frequently distribution of things like black holes are they way that they are.

Both approaches reverse the plausible order of cause and effect without a very strong motivation for doing so. Both engage in a poorly motivated attempt to create a distribution of possible universes and explain why we are in a particular place in that distribution.

String theory is doing something far more plausible. It is looking at 26 constants and guessing that there are really hidden relationships among them that allow you to derive most of them from a far smaller number of constants, if you just find the right unifying theory that explains hidden structure beneath the particles and forces which we observe.

Of course, string theory still leaves you with a handful of constants, but, to the extent that say 23 out of 26 constants are derived from the other three, the room to "fine tune" the universe through "cosmic natural selection" to look like what we see now, is greatly diminished.
 
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  • #17
String theory is doing something far more plausible. It is looking at 26 constants and guessing that there are really hidden relationships among them that allow you to derive most of them from a far smaller number of constants, if you just find the right unifying theory that explains hidden structure beneath the particles and forces which we observe.

that is a worthy goal, but as far as I know string fails. there is no accepted value of the string constant, there is no derivation of the constants of the standard model. there are no predictions concerning the results of future experiments.

indeed the tendency (since the KKLT paper of 2003) of string theorists to give up and appeal to the Anthropic Principle is a sign of desparation, dimming hopes of ever achieving that goal, worthy as it is.

I hope some completely new approaches are tried and some are more successful! It would be great to reduce the number of constants down to a handful from which all the rest could be calculated!

the room to "fine tune" the universe through "cosmic natural selection" to look like what we see now, [would be] greatly diminished

that would be great from a CNS viewpoint, one would have fewer undetermined parameters that one has to explain by an evolutionary mechanism :smile:

Just to be clear, CNS, of course, doesn't flow from the existence of life. But, I think it is fair to call it an AP like theory, because the type of reasoning is similar.

I agree, CNS and AP are different. It is also fair to point out the similarities, IF one is also clear about the differences!

IT IS POSSIBLE TO SHOOT DOWN THE PROPOSITION THAT THE UNIVERSE IS ADAPTED TO BLACK HOLE PRODUCTION. Indeed I would be delighted to hear that some highly reliable observation had ruled out CNS or made it highly unlikely. It is not something that one believes in, it is something that (I hope) will be tested. If it is ruled out (which would be progress according to conventional ideas of science where one proceeds by ruling out successive theories) then other mechanisms for determining the parameters of the prevailing models will, I hope, be proposed and tested in their turn.

By contrast, it is not possible to shoot down the proposition that the universe is suitable for life, or if you think it is, how do you want to go about it?
 
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  • #18
Ohwilleke it seems to me that CNS makes a strong assertion that the universe is optimized for black hole production. If that were shown not to be the case, i would be inclined to discard it. It would not hold much interest for me, although one could always add some assumptions to "patch up" and salvage the concept.

SAP, as i take it, only says that the universe permits life, it does not even say it is optimized for life. The existence of life is very difficult to count (except here on earth). The whole thing is a can of worms.

CNS is dealing with something we can observe all over the place, and count, and where we can hope to calculate how changing a parameter would affect BH abundance.

We can see lots of black holes. We can judge whether the parameters are optimal to make them abundant. If not, chuck the idea out. If they are optimal, then go figure (make up some explanation, the least bizarre that you can).

You seem to think that I am "reversing the normal order of cause and effect", or that somehow CNS does this. I am not and it is not. Nor am I trying to persuade you of anything implausible. I don't care whether or not you believe that BH can connect to BB. what I care about is knowing if the Standard Model parameters are optimized for BH production.

If they are then I would consider that a very remarkable fact requiring explanation.

I can't imagine you would not agree with the reasonableness of this.

Just find me one parameter which is not optimized for BH production. In principle it should not be all that hard.
 
  • #19
Before one goes about ruling out theories, one has to make a strong enough case that it should even be considered in the first place. [Time warp here. Your post above wasn't there when I posted this one and I will respond to your post above].
 
  • #20
Do you need a theory that predicts BH production? is not true that any
dynamic system must have a beginning and an end, cosmology is the only
science that seems to allow the possibility for perpetual motion, i hope
this is true in one shape or form.
But given an attractive force and a limited density area, i guess BHs are
inevitable.
 
  • #21
ohwilleke said:
Before one goes about ruling out theories, one has to make a strong enough case that it should even be considered in the first place...

So do you want me to make a bibliography of scientific papers that have considered CNS or of scientists (besides Smolin) whose current work bears on it? or a list of journals where their work has been published?

How do you want "a strong enough case" to be presented?

I don't have to persuade people to work on it. the papers go back to the 1990s, well before it came up on my radar :smile:

You seem skeptical that the idea has attracted interest, do you want a list of authors (besides Smolin) who have picked up on it, and a list of scholarly journals that have published what they'v had to say?
 
  • #22
The notion that there is an optimization for black hole production at all sounds quite weak for me. First off, it is not at all obvious to me, at least, that there is a strong connection between most of the standard model constants and black hole production.

A black hole happens when a sufficiently large star collpases. Thus, the frequency of sufficiently large stars is a major source of black hole frequency. The frequency of large stars are largely a function of how matter is distributed. A locally diffuse distribution of matter ought to discourage the formation of large stars, a locally compact distribution of matter ought to encourage the formation of large stars.

A very large proportion of all stars in our universe are not large stars. Our universe is littered with medium sized stars like Sol and with the remnants of stars that didn't end up as black holes because they were too small. Moreover, Hubble's constant and the accellerating expansion of the universe are making the universe ever more dense, hence discouraging black hole formation. A steady state or collapsing universe would be more likely to bring matter together to form black holes. (Optimizing black hole production is an amibiguous driver as it isn't clear if it refers to number of black holes, for which a steady state makes sense or aggregate black hole mass, for which a collapsing universe makes sense, but an expanding universe does not tend to maximize either, also that time at which black hole optimization is measures is unclear -- our universe spent heaps of time being radiation dominated with no black holes at all, clearly the current parameters didn't optimize black hole production during that era).

One can also look at the rate of fusion reactions, which flows to some extent from fundamental QM constants. If fusion reactions happened faster, large stars would produce black holes faster, resulting in more black holes at any given proper time from a big bang.

Second, while we in the process of tinkering with things we have no evidence can vary to create black holes, why not tinker with the law of gravity itself. Certainly, the law of gravity is not optimized for black hole production. If we want more black holes, first off, it should be stronger relative to, for example, the electromagentic force. And, wouldn't a formula in which the strength of gravity is related exponentially to mass say F=GM^2/R^2 in the classical limit, but much better at producing black holes?

And, why should the binding energy curve be what it is? If binding energy trough was say, Boron, instead of Iron, we'd have fewer heavy elements, and I haven't seen any strong arguments that heavy elements make black holes more common.
 
  • #23
wolram said:
Do you need a theory that predicts BH production?

Wolram, I will try to say something about the role of Quantum Gravity theory in this.

the core idea of CNS is that the parameters of physics MAY be fine-tuned for BH abundance. (if they turn out not to be, well and good, if they turn out to be then there is clearly something to explain)

After 10 years, since 1994, no one has reliably and conclusively shown that the parameters are not optimal for BH abundance----this is beginning to look suggestively like empirical evidence. a bunch of scientists have written about this.

where does theory fit in? Well starting this year we have been getting QG papers delving into the BH singularity and the math is still very rudimentary and inconclusive but it looks somewhat like the math that they found when they delved into the BB singularity.
This one could say is the barest whiff of theoretical support for one possible explanation of how the parameters could be fine-tuned, if indeed they are.

And they might not be! A parameter might be discovered to be totally out of line with making BHs abundant. But that hasnt happened so far. And then even if they are fine-tuned for making plentiful BHs one has the theoretical problem of explaining this and nothing is certain about that so far except that it is going to be really interesting.
 
  • #24
ohwilleke said:
The notion that there is an optimization for black hole production at all sounds quite weak for me. First off, it is not at all obvious to me, at least, that there is a strong connection between most of the standard model constants and black hole production.
...

Have you read http://arxiv.org/gr-qc/9404011
It is very detailed in how it connects various constants to black hole production.
it might help you to critique the main idea of CNS if you read that article
and challenged the connection on a point-by-point basis
 
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  • #25
So i guess this all comes about by how QG couples to mass?
 
  • #26
marcus said:
So do you want me to make a bibliography of scientific papers that have considered CNS or of scientists (besides Smolin) whose current work bears on it? or a list of journals where their work has been published?

How do you want "a strong enough case" to be presented?

I don't have to persuade people to work on it. the papers go back to the 1990s, well before it came up on my radar :smile:

You seem skeptical that the idea has attracted interest, do you want a list of authors (besides Smolin) who have picked up on it, and a list of scholarly journals that have published what they'v had to say?

First of all, popularity is certainly no sign pro or con of correctness. I similarly lament, as quite a few other physicists do, the lemming-like race towards string theory we've seen in the 1990s, and more generally, an undue tilt in the field from phenomenology to theory. Too many physicists make beauty their primary guide, rather than anamolous experiments. Too some extent, I think CNS is a product of the theory disease.

As far as a strong enough case goes, I mean in terms of physics. What is the current theory not explaining? Why can't black hole frequency simply be a product of our current set of constants -- independent of how those constants were "chosen"? After all, isn't a premise of CNS that black hole frequency is influenced by CNS through fundamental constant values? What does CNS add to an analysis based on analysis that uses the constants alone? Does CNS propose to provide insight into the value of some as yet undetermined fundamental constant?

One certainly can't directly observe CNS in action. The rest of the "multiverse" is on the other ends of the Big Bang and Black Hole event horizons, and while LQG may hypothesize that these aren't true singularities, it also doesn't offer any means of seeing to "the other side" of these phenomena. You have one data point and are trying to deduct what the distribution of other possible data points are without seeing any of them or knowing how they are distributed.

CNS also, by induction, appears to argue for the existence of some original ancestor universe. Yet, how can we know how far along we are generationally from the "first" universe, and are we any better off proposing some unknown force creating the original universe within a multiverse, than stopping our inquiry at the Big Bang, which we can observe indirectly, at least.

What does CNS have to recommend it over the "Big Bang was a random quantum fluxuation in the ZPE" within a larger but unitary universe theory? This, at least, has a connection to some phenomea that we know a lot more about, quantum fluctuations in ZPEs.
 
  • #27
ohwilleke said:
As far as a strong enough case goes, I mean in terms of physics.

Good, I was wondering. In that case i repeat my previous question:

marcus said:
Have you read http://arxiv.org/gr-qc/9404011 ?
It is very detailed in how it connects various constants to black hole production.
it might help you to critique the main idea of CNS if you read that article
and challenged the connection on a point-by-point basis
 
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  • #28
marcus said:
Have you read http://arxiv.org/gr-qc/9404011
It is very detailed in how it connects various constants to black hole production.
it might help you to critique the main idea of CNS if you read that article
and challenged the connection on a point-by-point basis

Selective issues with this paper:

Page 3, notes 1-2 -- the notion that there is more volume in a black hole measured from the inside than there is measured from the outside is dubious. More importantly, the mass inside a black hole is finite, and to propose that a black hole can generate a new universe is going to leave you with a pretty small universe in terms of aggregate mass-energy unless the conservation of matter and energy is not maintained -- yet, there is no evidence of any violation of matter-energy conservation. How is one modest sized black hole from a supernova collapse to generate enough mass to create a whole bunch of new black holes which can in turn create their own universes?

Moreover, if we are just one black hole in a prior universe and conservation of mass-energy is maintained, then the prior universe's physical constants can't be just slightly different, they must be radically different, in order to permit a black hole containing enough mass-energy to produce hundreds of billions of stars to be created from it to arise. Nothing even approaching our existing cosmology permits this.

Page 3, note 3 -- black holes do evaporate, albeit slowly. This means that the created universe will not only have finite and small aggregate mass-energy, but that this amount will decrease over time and that universes themselves decompose and evaporate through an originating black hole event horizon. If this were a process which happened only once and the original black hole were huge, this might not be a problem, but as the process of iteration starts every time a black hole is formed in a new universe, this creates a 10^54 Hubble Times limit on the age of the multiverse and also fails to explain why we don't detect symptoms of the evaporation of all the iterations of black holes that came before our own.

Page 4, Note 4 -- This is the ultimate bootstrap argument. We created a theory, string theory, to describe the universe, and because our theory is underconstrained and could produce multiple universes, we will conclude that there are multiple universes. This is an indictment of string theory, not an argument for a multiverse.

Page 4 -- this attempts to generate a probability distribution based on a single data point and mere speculation. It is thus, not well motivated.

Page 4, Note 5 -- The argument that an open universe is unlikely to produce an infinite number of black holes simply doesn't follow. Also, the very notion of "likely" in this context is exceedingly ill defined. In an theory so far outside the realm of what we have experienced, relying on mere intutition for a key parameter without rigorous analysis is questionable.

Page 4 -- as noted in my prior post, there is no convincing reason to limit ourself to varying parameters only if we are going to say that the laws of nature change when you pass through a black hole.

More specifically, why should be limit ourselves only to dimensionless parameters? After all, if we do not alter dimensional parameters, are we not concluding that we are not altering the question that says that the volume inside boundary is the same whether you measure it from the inside or the outside? (As it must be, if the dimensional parameter of the speed of light is the same in both cases.) And, if we do that, we have baby universes that are not only low in mass-energy, but also dreadfully small.

Page 5, Note 6 -- why shouldn't life be able to evolve in a universe without galaxies and stars? Clearly, such life would be different from life as we know it on Earth, but this seems more like a failure of imagination, rather than any meaningfully established conclusion.

Page 5 -- what good is a theory that applies to "nearly every universe" when we have only one to look at?

Page 6 -- the limitation of 20 parameters is both overbroad and underbroad. It is overbroad in the sense that almost no post-SM theory believes that there are really that many parameters, and underbroad because it doesn't consider other possible changes as discussed above. If many of these parameters are derivied from other parameters, than their relationship does not flow from CNS. It flows from the structure of the part of your quantum theory which is invariant from universe to universe within the multiverse, and thus you still have the question of "why is that so" and hence have gained nothing.

-------------------------------------------------------------------------

No more time right now, but this is a start.
 
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  • #29
ohwilleke said:
What is the current theory not explaining? ...

current theory is not explaining why the parameters of the standard model are the numbers they are

CNS is the only standing offer of an explanation for those numbers, at least that I know of.

(it does not explain the values of those numbers to say "they just happened randomly" by some vaguely conceived "fluctuation", one should seek out and test falsifiable theories which propose circumstances that force the numbers to be exactly, or nearly exactly, what they are)

ohwilleke said:
The notion that there is an optimization for black hole production at all sounds quite weak for me. First off, it is not at all obvious to me, at least, that there is a strong connection between most of the standard model constants and black hole production.

In that case, if it is not obvious to you, then you should read pages 6 thru 18 of Smolin's 1994 paper that I've given the link for several times. It goes into the physical connection between physical and astronomical parameters and black hole production
http://arxiv.org/gr-qc/9404011

you will not find "most" of the parameters connected to BH because there are a lot, but you will see examples of how some parameters are connected. Should we go thru these cases together in this thread? Have a look and see if you would like to do that. I am up for it. :smile:
 
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  • #30
Oh great! I just saw your post #28, which indicates that you are reading the Smolin 1994 paper. In fact although business calls you away, you were just getting up to page 6!

Page 6 is where the relevant part begins (connecting StdMdl params with BH). I shall welcome your comment on this section---pages 6 - 18 --- at your convenience. Thanks in advance. :smile:
 
  • #31
marcus
Garth alternative #3 is not the AP as commonly understood.

I think the problem lies in our different definitions of the Anthropic Principle.
I understand it to simply recognise the propitious nature of physical constants and attributes that could be otherwise.

In the CNS, after a sufficient number of iterations, I understand that every, or almost every, universe would have those 'constants' that maximise the occurence of Black Holes. These happen to be also those that are propitious for life, therefore every, or nearly every, universe will be propitious for life. This is the Strong Anthropic Principle by another name.

Garth
 
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  • #32
Garth said:
marcus
In the CNS, after a sufficient number of iterations, I understand that every, or almost every, universe would have those 'constants' that maximise the occurence of Black Holes. These happen to be also those that are propitious for life, therefore every, or nearly every, universe will be propitious for life. This is the Strong Anthropic Principle by another name.

Garth
Could you explain a little more how the propensity for black holes relates to the propensity for life?

Thanks.
 
  • #33
Mike2 said:
Could you explain a little more how the propensity for black holes relates to the propensity for life?

Thanks.

there are many ways it does, so the best would be if you would
look at
http://arxiv.org/gr-qc/9404011

you will not find it too difficult. it is not all formulas, and the equations are relatively simple and well-explained by words.

to summarize in a sketchy way:
for a universe to produce abundant black holes

1. it can't collapse immediately

2. it can't expand too rapidly or galaxies will never be able to form and stars to condense---it will just become a huge dilute gas

3. gravitating clouds of gas must be able to radiate away heat as they contract (in the real world molecules like CO play a facilitating role in this process)

4. to get plenty of stellar-mass BH you need lots of massive stars and they have to be able to eventually collapse. In the real world supernovae explosions catalyze star-formation by their shockwaves----there are chain reactions of supernovae on astronomical time and distance scales. This process accelerates star formation and therefore eventually BH formation.

5. it also enriches the interstellar medium with heavier elements like C and O, which facilitate the condensation of gas clouds to form stars, as I mentioned.

Basically, Mike, (well you should read about this not depend on my off-the-cuff summary which is quite sketchy and incomplete) the message is that when you look at the actual process by which galaxies collect and stars form and eventually make black holes------if you examine that process, you see things like the periodic table of elements playing a role, and the cosmological parameters that govern expansion playing a role.
So in a rough way one can say that what is good for making black holes is incidentally good for you and me either by accident, as a byproduct, or because we evolved to take advantage of the opportunities generated by black hole evolution, or for whatever reason.

In any case it appears (although it needs to be studied more and tested) that WHAT IS GOOD FOR THEM IS coincidentally GOOD FOR US.
 
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  • #34
Mike2 said:
Could you explain a little more how the propensity for black holes relates to the propensity for life?
Smolin's CNS initially does not bring life into the picture. The theory claims, contentiously, that the physical constants and attributes of the universe maximise the occurrence of black holes, which in turn then give 'birth' to other universes.

The theory nevertheless does give a thought out scheme by which these constants are determined. It makes no mention of life in their determination. However you cannot escape the fact that one property of a universe, which is highly sensitive to the exact values of some of these constants, is that it is also propitious for life. In not explicitly making that connection the anthropic coincidence (the correlation between the set of values for these constants and life) is implicitly hidden within the theory. As I have said above the result of CNS is that nearly every universe would be propitious for life and as such it provides one possible mechanism for the Strong Anthropic Principle.

Garth
 
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  • #35
Garth said:
...The theory claims, contentiously, that the physical constants and attributes of the universe maximise the occurrence of black holes, which in turn then give 'birth' to other universes.

The theory nevertheless does give a thought out scheme by which these constants are determined. It makes no mention of life in their determination. However you cannot escape the fact ...

To recapitulate what I said, for a universe to make a lot of black holes it has for example TO LIVE A LONG TIME and not collapse in a big crunch only a billion years or so into its existence. But a long lifetime like our universe is already over 13 billion years and no sign of ending, a long lifetime can also be taken advantage of by chemical molecules to start their biochemistry and their biological evolution---which needs time for random accidents to get it started. So that long lifetime of the universe is also, as a byproduct, a life-enabling feature.

and that is just one example. you can go down the line of what Smolin says it takes to produce lots of black holes. You can compare lists of what is desirable from one standpoint or the other.

forming black holes from stars requires you have stars (but carbonbase life can also take the opportunity presented by the star as an energy source)
so there is this overlap.

here is the list i made earlier of things. you can deduce the relevance
like having carbon and oxygen is good for this and also for that...

for a universe to produce abundant black holes

1. it can't collapse immediately

2. it can't expand too rapidly or galaxies will never be able to form and stars to condense---it will just become a huge dilute gas

3. gravitating clouds of gas must be able to radiate away heat as they contract (in the real world molecules like CO play a facilitating role in this process)

4. to get plenty of stellar-mass BH you need lots of massive stars and they have to be able to eventually collapse. In the real world supernovae explosions catalyze star-formation by their shockwaves----there are chain reactions of supernovae on astronomical time and distance scales. This process accelerates star formation and therefore eventually BH formation.

5. it also enriches the interstellar medium with heavier elements like C and O, which facilitate the condensation of gas clouds to form stars, as I mentioned.

... rough way one can say that what is good for making black holes is incidentally good for you and me either by accident, as a byproduct, or because we evolved to take advantage of the opportunities generated by black hole evolution, or for whatever reason.
 

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