The universe appears to be fine-tuned for life. For example, seemingly infinitesimal adjustments to the dark-energy density or gravitational constant would render most conceivable forms of life impossible. Adjusting the dark energy, for example, would result in either no planets or a collapsed universe.[1] Clearly, cosmic fine-tuning is necessary (although not sufficient) for evolution to occur.
Fine-Tuning Arguments
How do you explain it? As a Christian theist, I don’t find fine-tuning surprising. “God presumably would want there to be life, and indeed intelligent life with which (whom) to communicate and share love … and if he wanted to create human life in a universe at all like ours, he would have been obliged to fine-tune the constants.”[2]
Conversely, I suspect that fine-tuning ought to be surprising to the atheist. Accordingly, fine-tuning arguments (FTAs) tend to go something like this: “given theism, fine-tuning is not at all improbable; given atheism, it is; therefore theism is to be preferred to atheism.”[3] Presentations of and objections to FTAs can be quite complex. I’ll merely examine a couple interesting objections and one resolution proposed by Robin Collins.
Observer Selection
Often the skeptic will initially suggest that “were the universe not fine-tuned, we wouldn’t be here to talk about it.” Call this the observer-selection principle.[4] How exactly does this undermine FTAs?
All by itself, it doesn’t. Fine-tuning is like a firing squad. Suppose one is condemned to death. A platoon of expert marksmen aim their weapons and fire. Yet—miracle of miracles—one is not shot! What a wonderful surprise! But wait. The skeptic reminds us that if one had been shot, one would be dead and therefore not surprised. Surely this fact alone does not undermine one’s surprise to be alive against the odds.[5] The same applies to fine-tuning.
Enter the Multiverse
Therefore, in order to reduce the surprise of fine-tuning (without God) the skeptic must adjust the odds. This is where the multiverse hypothesis may prove helpful. The multiverse hypothesis “posits regions of spacetime outside our observable horizon, in which [physical] conditions are very different.”[6] These many regions are the product of cosmic inflation; the variation of physical parameters is a result of superstring theory.[7]
The multiverse hypothesis alone poses no problem to FTAs. “The fact, if it is a fact, that there are enormously many universes has no bearing on the probability (on atheism) that this universe is fine-tuned for life; that remains very low.”[8] What is needed—in order to put the multiverse to work against FTAs—is the observer-selection principle described above.
The multiverse hypothesis tells us that some universe amongst many others will support life. The observer-selection principle tells us that “we will inevitably find ourselves” in one such universe.[9] Working together, the multiverse hypothesis and the observer-selection principle appear to remove the surprise of fine-tuning without God.[10]
Mere Observers versus Privileged Observers
In order to defend FTAs, one must respond to either the multiverse hypothesis or the observer selection principle. Robin Collins does both. On the one hand, he argues that the multiverse hypothesis simply pushes “the problem of fine-tuning up one level to the laws required to generate the multiverse.”[11] On the other hand, he argues that the observer selection principle fails upon closer consideration. I’ll discuss this second approach.
Collins suggests that FTAs should not claim that the universe is fine-tuned for mere observers. Rather, our universe is fine-tuned for embodied conscious agents “who can interact with each other for good or for ill.”[12] Additional fine-tuning ensures “that those observers can develop scientific technology and discover the universe.”[13] So not only is our universe fine-tuned for mere observers, it is fine-tuned for privileged observers.
Suppose that the multiverse exists. Collins points out that most of the observers in the multiverse are not scientifically privileged like us. For example, “consider a universe with a dark-energy density a million times the value in our universe.”[14] In that universe, the increased cosmic expansion rate would reduce the Hubble volume so that nothing beyond the galaxy would be visible. This would seriously limit their ability to do cosmology. Even greater expansion renders evolution impossible.
Alternatively, if the strength of gravity were slightly increased, “any kind of technology would become more difficult, for example, building a structure to live in or perform scientific experiments would become more difficult.”[15] At a certain point, conscious life could only evolve underwater since “a life form with a brain large enough to qualify as an [embodied conscious agent] would be crushed.”[16]
Living underwater would “not allow them to develop scientific technology since they could not forge metals.”[17] Further increases in gravity would rule out underwater life completely. Just like with dark-matter, as gravity increases life first becomes less privileged scientifically and then becomes impossible.
However, some observers exist entirely independent of cosmic fine-tuning—Boltzmann brains. Such observers come into being via random local quantum or thermal fluctuations. They persist for a period long enough to make an observation and presumably vanish. Given a sufficiently large individual universe, these fluctuating observers will likely exist, without cosmic fine-tuning.[18]
Conclusion
The point is that very small changes in the cosmic fine-tuning parameters (dark energy and gravity) will rule out observers capable of science. Further changes will rule out embodied life all together. However, Boltzmann brains will still exist independently of cosmic-fine tuning.
All of this undercuts the observer selection principle. It is simply not true, on the multiverse hypothesis, that we are likely to find ourselves in a world such as our own. Indeed, “it is vastly more likely for a generic observer to find itself in the smallest and least structured community required for it to be an observer than in a larger highly structured community of observers, such as the human race.”[19]
So the question remains, why do we find ourselves in a universe fine-tuned for scientific civilization? Why are we not instead unscientific life-forms or Boltzmann brains? It would seem that the element of surprise remains, even given the multiverse. FTAs remain on the table.
[1] Furthermore, the laws of physics and the initial conditions of the universe are “set just right for life to occur.” Robin Collins, “The Fine-Tuning of the Cosmos: A Fresh Look at Its Implications,” in The Blackwell Companion to Science and Christianity, ed. J. B. Stump and Alan G. Padgett (Malden, MA: Wiley-Blackwell, 2012), 207, 210.
[2] Alvin Plantinga, Where the Conflict Really Lies: Science, Religion, and Naturalism (New York, NY: Oxford University Press, 2011), 199.
[3] Ibid.
[4] Collins, “The Fine-Tuning of the Cosmos: A Fresh Look at Its Implications,” 208.
[5] Plantinga, Where the Conflict Really Lies, 203.
[6] Sean Carroll, “Does the Universe Need God?,” in The Blackwell Companion to Science and Christianity, ed. J. B. Stump and Alan G. Padgett (Malden, MA: Wiley-Blackwell, 2012), 191.
[7] Ibid.
[8] Plantinga, Where the Conflict Really Lies, 214.
[9] Carroll, “Does the Universe Need God?,” 191.
[10] Collins, “The Fine-Tuning of the Cosmos: A Fresh Look at Its Implications,” 208.
[11] Ibid.; cf. Robin Collins, “The Teleological Argument: An Exploration of the Fine-tuning of the Universe,” in The Blackwell Companion to Natural Theology, ed. William Lane Craig and J. P. Moreland (Oxford: Wiley-Blackwell, 2009), 262–269.
[12] Collins, “The Fine-Tuning of the Cosmos: A Fresh Look at Its Implications,” 208.
[13] Ibid., 208–209.
[14] Ibid., 210.
[15] Ibid.
[16] Ibid.
[17] Ibid.
[18] Ibid.
[19] Ibid., 212.
Originally posted on Cognitive Resonance
So, John, it sounds like you want to say that the laws of physics and the values of the fundamental constants (which currently appear as underived values in those laws, and must be determined by experiment/observations – given that there are no ab initio means of calculating said values) are just unexplained (and possibly unexplainable) facts. Or, are you thinking in terms of a more fundamental physical theory that has no free parameters, one that unifies GR + QFT, and inevitably yields the values of the constants used by those theoretical models?
I absolutely agree with Ben’s statement that Fine Tuning is not surprising in Biblical Christian Theism’s view of the Creation. Whatever the underlying physics really is, I’m sure that God has already solved that problem, and it remains for us to discover His solution.
Fine Tuning does not imply necessarily that for our observable universe the fundamental physics(mathematical formalism and constants) could be different – you are right in the sense that they are what they are. The argument as I have come to understand it is more about how our observable universe would be different if the parameters are varied, and just how sensitive the universe is to those variations.
It’s the multiverse model that postulates universes with different physical laws (form and/or values of the fundamental constants) in order to account for the apparent fine-tuning of our particular universe.
For interested readers to follow up:
Here’s a nice summary I found over at the ASA website:
http://www.asa3.org/ASA/education/origins/anthropic-cr.htm, and for a more technical presentation:
http://arxiv.org/pdf/1112.4647v2.pdf
Yes, I think we don’t know a good explanation for why the physical constants are what they are. Maybe God did it, or maybe it’s just cosmically impossible for things to ever be different in any universe. We don’t even know if other universes exist at all.
Scientists say the probability of a universe having these properties (fine tuned to be “just right for life”) is extremely low. But how did the scientists calculate that probability? Did they see a number of different universes and note the rarity of universes with life? No. In fact, we have a sample size of just one, because we only know about our actual universe. So there’s no basis for saying the probability is low. As far as we know, judging from our test sample, the probability is 100%.
“You are alive, reading this web-page, because all dials are properly tuned.” But what if the dials are stuck and it’s just impossible to turn them?
@disqus_o63Z0grPLj:disqus
I asked the question of you to get to know you and your background a bit better. I realize now that it came off as high-handed. Please accept my apologies for giving offense, where none was actually intended. I’d just like to know if I’m interacting with someone who is a fellow professional scientist or not.
The second part of my comment was not specifically directed at you – I was expanding a bit on the OP.
In Riemannian geometry, the sum of the interior angles of a triangle only adds up to 180 (Pi) if the local curvature is 0 (Flat spacetime, or Euclidean geometry). For a triangle inscribed on the surface of a sphere, the angles add up to more than 180 (curvature > 0 ), for example. Thus, you are incorrect, the scenario is not impossible, in a more fundamental and comprehensive theory of geometry.
Before we go on to discuss modern theoretical physics, John, let me ask you what your professional scientific training is – do you understand General Relativity and Quantum Field Theory well enough to actually do the math? Do you know what the fundamental physical constants are? How are they all related? Show us the physics (I have a PhD in Physics, so I can handle the math if you can present it 🙂 )
There is even a more fundamental level to consider in fine tuning arguments – not only the specific values of the fundamental constants, but the very form of the fundamental principles of physics – why is the generalization of the principle of least action over an appropriate Lagrangian (or Hamiltonian) such a fruitful principle for understanding and describing the dynamics of a system? Why should a system’s dynamical symmetries lead to conservation of the corresponding dynamical variables? Why quantization and Lorentz covariance?
Space-time and particles/fields (or whatever is more fundamental than those) have inherent properties and dynamics that are describable by a scale-dependent set of unifying principles – so classical (Newtonian) dynamics is a good approximation for a regime that is not too big, not too small, and not too fast, and just how precisely one can observe and measure the system’s dynamical variables. Newton and his successors paved the way for developing the (simpler) fundamental mathematical principles that were needed for the more complex mathematics used by QM, GR and QFT and whatever is coming (String theory? Loop Quantum Gravity?, or something else) – this is possible only because of this scale hierarchy.
Wow, you’re really piling on the sciency buzzwords! One would almost think you were trying to intimidate me into silence. Hey, if you’re so smart, show me your theory of quantum gravity. I can read the math. Just copy and paste right into this little comment box here.
But seriously now, you didn’t answer my original question: Why does anyone suppose anything in nature could possibly be different? If the universe is Riemannian, then it’s Riemannian. Who says it could ever have been different?
Why does anyone suppose that the constants of nature could ever possibly be different? I think all the physical constants are related to each other, and they just are what they are. It’s like, why do the angles of a triangle add up to precisely 180 degrees? If the angles were off by even a tiny bit, there couldn’t be a triangle! So what? It’s an impossible scenario.