QUESTION: Would it be possible that a collapsing star directly become a neutron star without lightening up if the forces of nature were slightly different? For instance if the electrostatic force were a bit stronger the fusion of the protons would not happen. Same if the strong nuclear force were a bit weaker.
Also, isn't it weird that the speed of light is just exactly right to create stellar black holes from neutron stars ( when the neutron star mass is ~2 solar masses )? Aren't the chances of that happening by chance very slim?
Alas, if the changes noted by you were in effect, it would be doubtful there'd be any stars at all. No fusion process, say if the Coulomb repulsion barrier is too high to permit quantum tunnelling and even the most basic (H1 + H1-> D2) reaction. So no stars, or very few. And hence no collapsars at all. Bear in mind collapsars occur when the weight of the (mainly interior - metal rich) stellar layers far exceeds the outward radiation pressure as a result of fusion.
Of course, if the gravitational constant G were a bit greater, it is possible to imagine a preponderance of more collapsars since gravity would then almost always win the early battle v. radiation pressure.
In respect to the latter question(s), I am not quite sure what you mean, perhaps you could elaborate. What do you mean the "speed of light is exactly right to create black holes from neutron stars"?
Btw, the '2 solar mass limit' (threshold) to which you refer is not engraved in stone. I have seen recent estimates upward of 3 solar masses before a bona fide hole is formed.
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QUESTION: What I am wondering in all of this is : aren't the forces of nature and some of the constants not exact to produce stars and in particular stellar black holes? Could the stars and stellar black holes form with slightly different constants and forces?
Regarding my question about the speed of light, a priori the speed of light could be anything, it could be 10 times higher, 10 times lower or whatever.
Also the mass of a neutron star could a priori be anything, it could be like 10, 100, 1000 times lighter or heavier. A priori, the nuclear fusion process could produce a lot more or a lot less energy.
What are the chances that the speed of light needed for a neutron star to turn into a black hole be almost exactly in concordance with c. I know it is not exactly c, but it is in the same order of magnitude. Isn't that weird?
Ultimately hat I am wondering is if the universe in fact was not a huge machine to create those stellar black holes, for a reason that I don't know.
Sorry if what I say doesn't make sense. I have been thinking about that for quite some time now and I would greatly appreciate an educated opinion.
The trouble with most appeals to some kind of "fine tuning" of the constants of nature is: 1) most examples are cherry-picked or rest on selection effects, and 2) a goodly set of them are based on misunderstandings of physics.
In truth, the constants themselves as you note *could* be anything. Change this starting condition a tad, that a bit...and voila! a new c. A new neutron mass, whatever.
In one system at least, the value of c = 1, if you can believe it! What does it prove? Just that the physical constants are wholly arbitrary and ultimately depend for their value on the system of units being used.
The above applied to actual dimensional examples - say like the mass of neutrons (to alter to achieve some other outcome of the cosmos) discloses how sterile these sort of games are.
Thus, let's say one did conspire to "play God" and endeavor to create all neutrons to be a factor ten more massive than at present. What then? Well, the outcome would be there would be ten times fewer of them- hence the gravitational effect would be unchanged. In other words the *dimensionless* constant, F(G)/ F(E) remains unaffected. All you have done by altering the neutron mass in other words is diminish the number of neutrons in the cosmos.
Here's an example that further extends this: the force F(E) = 39 F(G). But what if instead we had, F(E) = 15F(G)? Well, in this case, as the force strengths are more in synch, stars would have collapsed long before any sentient life evolved to examine them!
Thus, the point is, when you fiddle with the constants of nature that matter (the dimensionless ones) you can get outcomes radically unexpected from merely altering one or two dimensional constants.
Now, since the speed of light, c is in itself arbitrary in this context, as is the neutron mass, then it follows that whatever product is hypothesized from their theoretical changes, alterations is purely artificial in terms of the time for it to form, or even to exist. Thus, asking when or how a neutron star "turns into a black hole" under these conditions is the wrong question. It doesn't- it stops at a neutron star, because you haven't altered α, F(G)/ F(E) or any dimensionless quantities that matter.
Thus, the universe is neither a "machine" to create neutron stars, black holes, quasars...terrestrial planets with life..or anything else. All of what it *can* create or *may* create (by playing with whatever constants) exists purely in the mind of the beholder. I call it a "mental artifact" or fabrication, to distinguish it from an empirical construct.
To fix ideas here: consider E = mc^2, which Einstein equation constitutes a specific formalism for a very particular operational definition linking energy and mass. We say it is a closed formalism, embodying closed symbols and operational definitions.
Scientific epistemology allows us to regard E, m and c as constructs, connected via operational definition to what we call P- (perceptual) facts. That is, these facts are based on experimental measurements confirmed numerous times (even though as I noted, technically c is an arbitrary constant contingent on unit selection.)
Thus, we expect a correlation like:
C <-> P
between the construct "mass-energy" and the perceptual fact (which may be seen as the fission of an atomic nucleus and a particular resonance pattern that arises)
re-affirming closure, significance and NO meta-linkage.
But as Philosopher of Science, Henry Margenau has noted, in the absence of P-facts and defined C-constructs, any syllogism or argument(or inference) will have too many meta-statements, and break down to mere circularity.
Alas, this is the problem with those (not necessarily you!) who play with things like the anthropic principle in the hope of finding meaning to the cosmos via some fine tuning. Then are amazed when they come out at a dead end. They've extended science beyond what it can deliver.
Hope this makes some sense, don't know if it does!
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QUESTION: I understand what you mean. Indeed the anthropic principle is a problem.
I imagine that our universe is the best possible for life, because if another type of universe were better, according to probabilities we would live in this type of universe.
So basically maybe most of what we see in our universe may be "finetuned" for life. So it's difficult to generalize any of its characteristics.
In fact I was wondering about all that because I was thinking that maybe universes could evolve. Leonard Susskind compares the universe to a creature with a sort of DNA and each universe would have its own "DNA".
I was thinking that if there is a very high number of universes, perhaps sooner or later an evolutionary process would begin. That would produce an enormous number of possibilities, and lead eventually to our universe.
My idea was that the stellar black holes were like the seeds of our universe. Universes would grow from those black holes through a big bang process pretty much like a tree grows from a seed through germination.
The universe would have become fine-tuned to produce those black holes by evolution.
If this process is not the right one - and I know it probably isn't.. - perhaps there is another sort of reproduction phenomenon that would lead to all sorts of universes.
Very farfetched idea but our universe is very farfetched to begin with..
Thanks a lot for taking the time to answer my questions.
Your speculations are quite interesting (as are Susskind's) - but in general I tend to be leery (extremely so) of anything that remotely smacks of "animism" or teleology. In my purview, which I admit is not absolute but only based on the evidence at hand, I see only a physical ensemble unfolding according to pre-defined natural laws and wholly purposeless, as well as lifeless - in the sense that inanimate matter is "dead" and exhibits no consciousness.
As for "evolution"- since we understand it to be based on natural selection, I don't see it in any way applicable outside the biological sphere. Certainly not to black holes, etc.
I am also leery of the multiverse theory, such as put forth by David Deutsch ('The Fabric of the Universe') and others. While Deutsch does provide a few clues of how an interphase between adjacent universes might be detected (via interference patterns) I am still not convinced there is enough there to treat the concept as anything other than an artifact - perhaps analogous to the old Ptolemaic "epicycles" - needed to contrive an explanation for planetary motion.
So, I guess from that angle, you might call me a killjoy!
Anyway, it's good to see a questioner able to think at a deep level - if a tad on the fantastic side!