Cosmic Darwinism featured in new view of the universe

[oldman]

Reminds me of the Greek Mystics philosophy -- most of 'mainstream' cosmology does.

Or maybe a more modern version of: How many angels on the head of a pin?

Modern cosmology is a lot more difficult than the old Greek stuff. A huge number of facts provided by both old and modern astronomical instruments have to be reconciled with speculation, which as you correctly suggest is a favourite and usually futile human occupation. This difficulty is compounded by the impossibility of contolled experimentation with cosmology. But all the plethora of stuff around us is so complicated, and keeps on turning out to be so surprisingly vaster and stranger than we had supposed, that informed speculation is a more helpful tool than in other more down-to-earth sciences.

The question Marcus poses:

... the parameters are adapted so as to make a lot of black holes. Adapted so well that no small change could produce an improvement---that is, and increase in the number of black holes

The question is, is this true or not?

is (to my way of thinking) a sensible one, given Lee Smolin's speculations, which are indeed pretty wild. But it is properly formulated and deserves an answer - yes or no - which could be scene-changing.

Be good if Clever Folk gave it a whirl.

 

[Rymer]

Reviewing the Thirty -- while they are reported as unitless numbers I don't really agree with that generalization. They ALL have implied units from the relations they are used in. Which means that they all only have meaning in those relations.

Also all the values are dependent on how well their related theory determined relations actually work -- and how complete or contradictory they are.

And that doesn't even include the assumptions about 'black holes'. (Which I still do not believe exist as described.)

 

[Dmitry67]

Reviewing the Thirty -- while they are reported as unitless numbers I don't really agree with that generalization. They ALL have implied units from the relations they are used in. Which means that they all only have meaning in those relations.

Lets take mass spectrum
Masses are reported in GeV,
but when the are normalized by say M(e) they become unit-less

 

[Rymer]

Lets take mass spectrum
Masses are reported in GeV,
but when the are normalized by say M(e) they become unit-less

Yes, but they are still 'masses' and are identified as such in the relations used. Converting to 'unit-less' doesn't give them any new significance. Use and comparison of such values can only be done using the relations for which they have meaning.

I'm not sure what 'property' or 'importance' is attached to such parameters by making them unit-less. Sometimes it does simplify the relations -- and some times not. But it should never change the meaning of the relations.

 

[Dmitry67]

Yes, but they are still 'masses' and are identified as such in the relations used. Converting to 'unit-less' doesn't give them any new significance. Use and comparison of such values can only be done using the relations for which they have meaning.

I'm not sure what 'property' or 'importance' is attached to such parameters by making them unit-less. Sometimes it does simplify the relations -- and some times not. But it should never change the meaning of the relations.

Haha!
So how do you measure the mass?
In GeV?
By definition, you make some unit-less comparison with the electron properties :)

 

[Rymer]

Haha!
So how do you measure the mass?
In GeV?
By definition, you make some unit-less comparison with the electron properties :)

And whatever the result is its still 'mass' -- and it has no other 'properties' added.

My point in questioning this is that by restricting ourselves to 'unit-less' parameters we may be ignoring important other relationships between the various parameters -- where relations don't meet this 'unit-less' concept.

(note there is a problem with 'mass' specifically -- whether its inertial or gravitational -- and whether G is involved, etc.)

 

[Dmitry67]

Dont you agree that Planks Units are the most natural system?

 

[marcus]

My point in questioning this is that by restricting ourselves to 'unit-less' parameters we may be ignoring important other relationships between the various parameters -- where relations don't meet this 'unit-less' concept.
...

OK, at first sight that seems possible. But this is the conjecture----optimality of 30-some unitless parameters. It can be checked. In scientific pursuits you have to do one thing at a time. You can formulate a different conjecture if you want, involving some other quantities.

A priori it seems fruitless to argue about what is the "correct" conjecture to propose. You propose something, you test it, you move on from there.

You might be interested in the rationale for why people consider the unitless parameters to be the decisive inputs. When Nobelist Wilczek wants to list the parameters describing the universe and particle physics he specifically focuses on unitless (it says so in the title: "dimensionless"). When John Baez wants to add a page about the standard model parameters to his FAQ he focuses on the unitless numbers. Why would these people automatically do this? The practice probably goes back more than 50 years---I don't know. Anyway it is traditional, conventional in physics. Why?

I think it is because of a thought experiment. First you obviously only need to add 3 quantities to the 30 numbers. Because G, hbar, c automatically give units of mass, force, density etc. Temperature is basically an alternate energy scale, and not relevant at the individual particle level anyway.

Dmitry already pointed out the Planck quantities to you. Simply having G, hbar, c automatically gives you all the reference quantities you need----so all you need after that is pure numbers.

So your quibble with the CD conjecture comes down to saying "shouldn't it also contain G, hbar, c too?"

Well this could be more of a philosophical issue, but a certain thought experiment comes in. Suppose you could communicate with someone in a completely alternate universe totally isolated from ours and make measurements and communicate dimensionless numbers.
You describe the role of G, hbar, c in your physics formulas, and he says he has the corresponding formulas with corresponding quantities. So you can express masses as pure numbers which are ratios to the natural unit, the Planck mass, in each universe, and you compare and you discover that you both have the same unitless numbers describing your universe!

The only thing you can't compare are actual physical (non-numerical) quantities, like a quantity of inertia. Because you can't pass physical things back and forth.
Now does it make any sense to say that your universes have different physics?
In what sense would it be meaningful to say that the electron has different masses in the two places? Would it be meaningful to say light travels a different speed?
Are atoms a different size?

I believe if you think carefully about it, you will come to the same conclusion I do:
in describing two universes all that matters are the proportions---the pure numbers.
If all the proportions are the same then the two look the same, in their basic physics.
It makes no sense to ask if c is the same speed in the two places.

If there is no physical contact, no overlap, how would you tell? Try to think of an experiment that would tell (which does not depend on other quantities already measured in terms of c, and the other two G and hbar.

In other words, if the Thirty unitless numbers are the same, then "changing" G, or hbar, or c would have no effect on anything. You could not experience it. Not only would the number of stars be the same, and then number of black holes, but stars would work exactly the same, and the average sizes and composition of molecular clouds, and planets for that matter, would be the same.

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

btw you made a point about the difference between inertia and gravitational attractiveness. I think the attractiveness is measured in terms of L³/T². and inertia is measured in terms of M, whatever the mass unit is. And G gives you the conversion between them. How many units of L³/T² for each unit of M. Once you have G, hbar, c you automatically have quantities of length, time, and mass to compare stuff to, and that takes care of both gravitation and inertia. So I would say the point you raise there is not a problem. Let me know if I am missing something.