Fine-Tuning Problem in Cosmology

[Fudbucker]

One possible explanation: the "real" universe (the one running the simulation) may be a cyclical universe.

1 Wouldn't it be easier to apply that solution to this universe? Why add a layer?

Or the values of their physical constants might not even appear fine-tuned.

2 Or they may be able to see that just because the "appear" fine-tuned does not actually make them fine tuned?

Or they have a natural explanation for why the universe is the way it is.

3 Something like: If it wasn't we wouldn't be here to observe it?

Lots of reasons why there might not be a fine-tuning problem in the "real" universe.

All seem to apply equally well to this universe.

1. Our universe doesn't appear the cyclical. The expansion rate is too high to end in a Big Crunch. That doesn't mean it eventually won't, but it's not looking too likely.

So a cyclical universe simulating a universe like ours wouldn't apply to our universe that well. There's too many observations that don't support the cyclical model.

2. If something appears surprising, it needs to be explained. You're implying that the universe that's simulating ours has the same fine-tuning problem but they have chosen to ignore it (or not give it any significance, or chalk it up to coincidence). That's not very likely, unless their scientists aren't very bright.

3. No, a "natural" explanation means a set of natural laws from which the values of the physical constants could be derived from. Example: if you were unaware of evolutionary theory, you might conclude that lifeforms were designed and put here on Earth. However, as you learn the natural theory of evolution and see the supporting fossil evidence, you would ditch the design theory, because there would be a set of natural laws that explain what, at first glance, appear to be intricately designed life forms.

The universe that's simulating ours may have discovered those kinds of natural laws. We, so far, haven't, and it's looking more likely that we won't- that the way our universe happens to be was an accident.

 

[Toontown]

And where is a citation about my question?

Where are the ranges and constrains of the constants, and any other support for the totally speculative and moot FTA?

What constraints?

You have it backwards.

You need to tell me what the constraints are, if you want to take issue with my default assumption that the "constants" are variable in an inflationary multiverse. Which, of course, you cannot do, because, after decades of intensive investigation, no one has found the first clue that any such constraints exist.

It is your assumed constraints which are "totally speculative".

 

[Toontown]

And where is a citation about my question?

Where are the ranges and constrains of the constants, and any other support for the totally speculative and moot FTA?

It has now occurred to me that this may be the object of your vaguely worded desire - life-allowing ranges and constraints of constants.

http://en.wikipedia.org/wiki/Fine-tuned_Universe

Although that also seems unlikely to be what you want to look at, since you declared the FTA moot in the same sentence you asked for the nonspecific "ranges and constraints". It seems unlikely that you'd want to look at something you've declared moot in the same sentence you asked for it.

 

[Kevin_Lowe]

What constraints?

You have it backwards.

You need to tell me what the constraints are, if you want to take issue with my default assumption that the "constants" are variable in an inflationary multiverse. Which, of course, you cannot do, because, after decades of intensive investigation, no one has found the first clue that any such constraints exist.

It is your assumed constraints which are "totally speculative".

Hang on, when did an inflationary multiverse with variable laws of physics become the default? I must have missed that bit.

 

[Dancing David]

What constraints?

You have it backwards.

You need to tell me what the constraints are, if you want to take issue with my default assumption that the "constants" are variable in an inflationary multiverse. Which, of course, you cannot do, because, after decades of intensive investigation, no one has found the first clue that any such constraints exist.

It is your assumed constraints which are "totally speculative".

Or that they are variable, sheesh?

There is no default position, it is all speculative.

Is that something you would agree to?

 

[Dancing David]

It has now occurred to me that this may be the object of your vaguely worded desire - life-allowing ranges and constraints of constants.

http://en.wikipedia.org/wiki/Fine-tuned_Universe

Although that also seems unlikely to be what you want to look at, since you declared the FTA moot in the same sentence you asked for the nonspecific "ranges and constraints". It seems unlikely that you'd want to look at something you've declared moot in the same sentence you asked for it.

You are assuming that the constants could be variable, which is a speculative stance.

 

[Toontown]

Hang on, when did an inflationary multiverse with variable laws of physics become the default? I must have missed that bit.

I said it was my default assumption. Earlier I asked why it shouldn't be the default assumption.

 

[Toontown]

Or that they are variable, sheesh?

There is no default position, it is all speculative.

Is that something you would agree to?

Yes, a default assumption is speculative. All hypotheses are speculative, otherwise they would be classified as theories.

 

[Fizil]

There are many problems with fine-tuning arguments, but I want to highlight one:

Fine tuning arguments always look at how a single parameter varying effects the evolution of the universe. For instance, the formation of galaxies requires that the cosmological constant be "fine tuned" near the value it is at. Right? No. Let's say we let the density fluctuations of the early universe also vary in magnitude. Now the "fine tuned" value needed for the formation of galaxies varies with the size of the density fluctuations. (eta: full disclosure, I think I got this argument from Lee Smolin, a scientist who actually agrees there is a fine tuning problem that needs to be explained).

The point is that changing something like the fine structure constant by some amount might make OUR universe uninhabitable, leaving everything else constant. But there could be many possible values all the other constants could take that could result in complex life producing universes even if the fine structure constant was significantly different than it is in our universe.

A related point is that many "fine tuned" constants are only fine tuned because of faulty reasoning. For instance in the above case of galaxy formation the argument typically begins something like "Galaxies are needed for life". Galaxies might make life more probable, but life is surely compatible with universes with more diffuse structure, or even more compact structure (there don't need to be so many galaxies, one is certainly enough to produce at least 1 life sustaining planet). Therefore the initial assumption that life requires the galaxy formation seen in our universe is invalid, all you have shown is that our universe is "fine tuned" for the sort of galaxy formation we observe.

eta: As I mentioned above, I believe I got that argument from Lee Smolin, who has a lot of interesting ideas, even if I don't necessarily agree with many of them. His idea of cosmological natural selection in particular is an attempt to explain the initial conditions of the universe without resorting to an infinite multiverse + anthropics, or creationism. Basically the idea is that universes form from black holes in a parent universe, and at the formation event the fundamental constants are somehow randomized. This is where the 'natural selection' part comes in, within the population of universes, those that maximize black hole creation will dominate. Thus we should expect the constants of nature to be near those values that would maximize the number of black holes. An interesting idea, but I disagree with him that it is really falsifiable. It is always possible we are in an atypical universe, meaning any prediction based on what we should see in a typical universe may prove to be wrong, even if the theory was in fact correct.

 

[Perpetual Student]

Fine-tuning does not seem to me to be a "problem" as much as it is a stimulus for a number of speculative questions.
Those questions are as follows:
Is it an inherent property of the universe that makes all the fundamental constants inevitably the values we measure?
At the time of the big bang (or before) could any of the constants have been something other than they are now?
Could there be other universes with different fundamental constants?
There was a time when men marveled at the fact that the earth was in such a perfect location for the creation and sustenance of life.
We now know that the vastness and complexity of the universe is such that planets can take on a virtually infinite number of orbits around a virtually infinite number of stars, making the earths particular circumstance a matter of chance.
Could there be an analogous situation with our particular universe being one of a possible infinite number of universities in a vast megaverse?
While there may be no scientific way in which to confirm or reject any of these speculations, it seems to me these speculations have a scientific basis and are quite fascinating.

 

[Kevin_Lowe]

I said it was my default assumption. Earlier I asked why it shouldn't be the default assumption.

Well, because that would be shifting the burden of proof.

You can assume whatever you like, it's a free message board, but it's not up to other people to prove that your assumptions are wrong. If you want anyone else to assume the same things you do, it's your job to advance a positive argument as to why they should do that.

 

[Dancing David]

Yes, a default assumption is speculative. All hypotheses are speculative, otherwise they would be classified as theories.

That is an interesting perspective, so you agree that the FTA is based upon speculation?

 

[Dancing David]

I said it was my default assumption. Earlier I asked why it shouldn't be the default assumption.

Nope burden of proof is on the claimant. I would say that all possibilities are likely in speculation, constrained, partly constrained and free to vary.

So the null hypothesis would be all possibilities.

 

[Pup]

So let's say this conversation is taking place before life evolved anywhere in the universe. (Paradox, I know; just bear with me.) Would there still be a fine-tuning problem? Did the universe look equally special before we knew life would evolve in it?

 

[Perpetual Student]

So let's say this conversation is taking place before life evolved anywhere in the universe. (Paradox, I know; just bear with me.) Would there still be a fine-tuning problem? Did the universe look equally special before we knew life would evolve in it?

Yes.

 

[Fudbucker]

So let's say this conversation is taking place before life evolved anywhere in the universe. (Paradox, I know; just bear with me.) Would there still be a fine-tuning problem? Did the universe look equally special before we knew life would evolve in it?

Yes. If the values of the constants are random, universes with complex structures (galaxies, stars, varieties of atoms, molecules, planets) would be very rare.

"Steven Weinberg[12] gave an anthropic explanation for this fact: he noted that the cosmological constant has a remarkably low value, some 120 orders of magnitude smaller than the value particle physics predicts (this has been described as the "worst prediction in physics").[13] However, if the cosmological constant were only one order of magnitude larger than its observed value, the universe would suffer catastrophic inflation, which would preclude the formation of stars, and hence life.

The observed values of the dimensionless physical constants (such as the fine-structure constant) governing the four fundamental interactions are balanced as if fine-tuned to permit the formation of commonly found matter and subsequently the emergence of life.[14] A slight increase in the strong interaction would bind the dineutron and the diproton, and nuclear fusion would have converted all hydrogen in the early universe to helium. Water, as well as sufficiently long-lived stable stars, both essential for the emergence of life as we know it, would not exist. More generally, small changes in the relative strengths of the four fundamental interactions can greatly affect the universe's age, structure, and capacity for life."
http://en.wikipedia.org/wiki/Anthropic_principle#Anthropic_coincidences

 

[Kevin_Lowe]

So let's say this conversation is taking place before life evolved anywhere in the universe. (Paradox, I know; just bear with me.) Would there still be a fine-tuning problem? Did the universe look equally special before we knew life would evolve in it?

I'm open to persuasion but I think this question is incoherent, because we have to ask "did the universe look special to who?", and there is no "who" in play.

Fudbucker's answer, for example, assumes a viewer who likes hydrogen but not helium, likes planets and not gas clouds and so on.

 

[Strawman]

We've had a bit of a heated discussion in the R&P section about whether fine-tuning is a problem in cosmology. So I thought I would take a poll.

This is the best summary of the fine-tuning problem that I could find:

"... if these fundamental parameters had been different from the time of the Big Bang onward ..."
pbs dot org

The fine tuning is extremely interesting and interdependent, but beyond that, I and many others question the presumption of a big bang.

 

[Pup]

I'm open to persuasion but I think this question is incoherent, because we have to ask "did the universe look special to who?", and there is no "who" in play.

Fudbucker's answer, for example, assumes a viewer who likes hydrogen but not helium, likes planets and not gas clouds and so on.

I guess that's part of what I'm curious about. If we think the universe is special because it's fine-tuned for life, well, it was the same universe before life evolved, but would it have been considered fine-tuned then? If not, then there's nothing special or fine-tuned about our universe as a universe.

 

[turingtest]

So let's say this conversation is taking place before life evolved anywhere in the universe. (Paradox, I know; just bear with me.) Would there still be a fine-tuning problem? Did the universe look equally special before we knew life would evolve in it?

I think it's a valid question, because it touches on a point that was raised here earlier- it's not really paradoxical if you rephrase the last question as "does the universe look equally special, as in 'fine-tuned for life,' before we even know how much life is in it?" The whole thing revolves around whether life is the point of the universe, or simply an outcome of its processes; and without more information than we have at present- so far as we know now, the only life in the universe is here on earth- there's no way to to turn what is an interesting question into a valid conclusion.* I don't think anyone questions that life is a result of the way the universe works; but, while a result may also be an aim from "fine-tuned" design, it takes more than an inference (by the putatively designed) to make it so. Design requires agency; to prove the agency, you need something independent of the perception of design, or all you're doing is reasoning in circles (or indulging in tautologies).

*And even with more information about how common life may (or may not) be in the universe, there may still be no determinate answer. After all, a theory ("fine-tuning") that can accommodate any evidence ("life is common" or "life is uncommon") isn't a theory at all, it's a faith.