God is the best explanation for the fine-tuning of the universe for life
“The more I examine the universe, and the details of its architecture, the more evidence I find that the Universe in some sense must have known we were coming.“ – Physicist Freeman Dyson
“A commonsense interpretation of the facts suggests that a super-intellect has monkeyed with physics, as well as with chemistry and biology.” – Astronomer Fred Hoyle
As modern scientists discover more and more about the universe, they have also discovered how remarkable and improbable it is that the universe is the way it is. Not only does the universe exist — which is incredible enough — but the laws and constants of nature are set up in such a way that allows living creatures to emerge, flourish, and discover the universe they live in.
That might not seem remarkable. After all, we’re here, right? If we weren’t here, we wouldn’t be asking why the universe is the way it is in the first place. Yet the universe did not have to be that way. The more knowledge we have about the behaviors and patterns of everything in the universe, the more it’s become clear that they depend on extremely precise laws and values — so precise that it boggles the human mind. Scientists, atheistic and theistic alike, have found that the initial conditions of the universe had to be so incomprehensibly precise to allow for the emergence of not just life, but any coherent structures whatsoever, that they call it the “fine-tuning” of the universe.
What is “fine-tuning”?
Imagine that you have somehow acquired access to a room that contains a series of old-fashioned radio dials. If you owned a car before the 1980s, these look very familiar to you. It shows all the possible ranges of radio frequencies, on one display, and turning a dial will allow you to move a needle between one station and another. (If that still doesn’t make sense to you, Google “car radio dial” and come back.) But these dials don’t play music — they represent all the constants and quantities that govern the material universe.
They are neatly and clearly labeled. Some of them you (and I) may not understand, unless you have a degree in astrophysics. But others seem pretty clear, representing things like gravity, the speed of light, and the number of dimensions in spacetime.
Any reasonable and sane person would never touch anything in this room, for fear of what might happen. But of course, you are no reasonable or sane person on this day. After all, you’ve somehow managed to gain the ability to change the values of the constants and quantities that govern the entire universe. Not many reasonable or sane people manage to do such things.
So you approach one that looks familiar. This dial represents the strength of the gravitational constant, which controls the force of gravity. It’s right next to dials that represent the strength of the electromagnetic force, the weak force, and the strong force — the four fundamental forces of the universe. You notice that gravity is set much lower than the other three. There are an enormous number of increments on these dials — if you could count them, there would be a gap of 10^40 (10,000,000,000,000,000,000,000,000,000,000,000,000,000) increments between gravity and the strong force. This is because gravity is 10^40 times weaker than the strong force.
Although it’s impossible for you to see all 10^40 increments on this radio dial (if each of these increments were just an atom’s width apart, the dial would be several times the size of the Milky Way), you are somehow able to nudge that dial up by the smallest measurable distance in the universe.
Upon doing so, the universe instantly implodes upon itself.
You are safe, because of course the ability to change the fundamental constants and quantities in the universe can’t come from within the universe; you have a safe vantage point from outside. Silly me, you think. Of course I can’t just change the force of gravity now. Every structure in the universe is built based on the current strength of gravity. Of course they would all collapse if that changed. But what if it was that way from the beginning? What if that dial was an atom’s width closer to the others since the Big Bang? Then all structures would form based on that. How would the universe look different today? What if you just changed the initial conditions of the universe? (After all, if we are talking about design in the universe, we want to go back to the time it was designed.)
Luckily, you find that there is also a dial of time in this room. So you turn back the dial of time 13.8 billion years, all the way back to the Big Bang, change the setting of gravity by that tiny increment once again, and return to the present time, to see how different the universe looks.
Well, good news! You didn’t destroy the universe. It still exists. But it looks very different. For example, there is no sun. It died out long ago, because in this high-gravity world, stars could never last five billion years like the sun has (cosmologist Martin Rees puts the upper limit on the lifetime of a star at 10,000 years in such a universe.) Actually, according to philosopher Robin Collins, who has studied the fine-tuning of the universe extensively, even a 3,000-fold increase in gravity would be enough to prevent stars like the sun from existing. Your tiny movement of the dial — equivalent to the width of a single atom if the dial were as long as the observable universe — was still a billion-fold increase in gravity.
The Earth does survive, but as a tightly compressed little ball, not much larger than a basketball court. If a living creature could exist in this universe, according to Rees, it could not be much larger than a very thick-legged insect. Any creature near human-size would be crushed.
So that was a bad idea. You reset to the time of the Big Bang and start over. What if you lowered gravity instead? Well, you can’t do that very much either; if you have too little gravity, planets will have a harder time holding on to an atmosphere, and eventually they will have a hard time coalescing together into large bodies at all.
Enjoy your universe of pebbles.How about going to the other end of the scale, to the strong force? It would seem like that one, being 10^40 times stronger than gravity, has some room to spare. The strong force is what keeps protons and neutrons bound together in the nuclei of atoms. It has to be strong enough to overcome the electromagnetic force, which would normally repel protons (positively-charged subatomic particles), and indeed it is — 137 times stronger at a distance of 1 femtometer.
Martin Rees has something to say about this, too. In his book Just Six Numbers, he notes that the strong force helps determine a value that scientists call ε (epsilon), a measure of the nuclear efficiency of the fusion of hydrogen to helium in stars. This value, mathematically, is 0.007. What if you moved the dial just a little, so that the value was 0.006?
You do so, and you return to the present to find…nothing. There’s space there, yes. The universe exists. Spectrometry readings would tell you there is a lot of hydrogen present. But there’s nothing else. You’ve made the strong force too weak to help facilitate hydrogen fusing into helium, and in turn to heavier elements like carbon and oxygen, which are rather important.
You reset. Maybe moving the dial up a notch will make something interesting. Now the value is at 0.008. You take it to the present day, and…
You see a universe that at a very brief glance looks familiar, with stars shining brightly, but not a whole lot else going for it. That’s because now you’ve gotten rid of all the hydrogen. The fusion process was so sufficient that all the hydrogen has fused to helium! That’s bad news for somewhat important chemical compounds like water (H2O), and therefore living creatures.
You sigh. This clearly isn’t working. Is there any way to create some kind of interesting alternate universe? You move to a different category. There’s one dial that represents something called the “cosmological constant.” The cosmological constant, you later find out, is what governs the rate of the universe’s expansion. It should be a fairly high number, according to physicists’ calculations. But to everyone’s bafflement, the cosmological constant is extremely low: 10^-122. That’s a decimal with 122 zeroes and then a 1.
So what if you turned that number back up to where it “should” be? You’ve already destroyed the universe several times. How much worse can it get? You give it the slightest nudge upward, and return to the present. To your disappointment, you return to the present to find nothing but blackness as far as the eye can see. Turns out you made the universe expand so fast that matter didn’t have time to gather together into clumps to form structures like stars, planets, or anything, really. When you reset and try to move it the other direction, the universe can’t expand and collapses in on itself.
Okay. This was not as much fun as you thought it would be. As you keep trying to alter different laws and constants, you find that it seems like no matter what you try, if you mess with anything by the slightest amount, you get a life-prohibiting universe. Mess with the mass of the neutron by more than 1/700, and you find a universe with no stars, because nuclear fusion is impossible. Mess very much with the electromagnetic or weak forces, and you make essential chemistry impossible.
Almost every time, you return to the present to find a black void of nothingness — if you even get space at all.
You decide to try one more thing. You find a dial labeled “entropy.” This one represents the amount of entropy present in the early universe. Entropy is the degree of “thermodynamic order” in the universe; entropy is gradually increasing, and at maximum entropy, the universe would be one completely cold, uniform space. Low entropy, therefore, is important for the existence of any structures like planets and galaxies and living creatures. British physicist Roger Penrose has calculated that the odds of the entropy in the early universe being so low are 1 in 10^10^123. That’s 10 with 10^123 zeros after it — a number so large that if you wrote a zero on every atomic particle in the universe, you still would not have enough space to write it.
It turns out the universe exists in a balance of laws and constants so delicate that the slightest alteration would render the universe lifeless, if it survived at all.
You can do nothing but stare in amazement. How did it all get to be this way? All these dials at all their unbelievably exact settings? If these dials had been set at random when you entered the room, you could try for millions, billions, trillions, quadrillions, quintillions, etc. of years on end and never get the settings right. If you can’t do it, how could they possibly have gotten to be that way on their own?
Physical necessity, chance, or design?
The fine-tuning of the universe for life is not very controversial among scientists. What is controversial is the explanation. Consensus is that there are three possible explanations:
One is physical necessity. Maybe there is some yet-unknown law or Theory of Everything that explains why all these laws and constants have to exist in such precise relations with each other. But so far nothing of the sort has been forthcoming. Even if it were, it wouldn’t eliminate the need for an explanation of fine-tuning. Any sort of law, value, or mechanism sophisticated enough to hold all these values in a life-permitting range would itself cry out for an explanation. You would simply be kicking the problem up a level. Physical necessity is an implausible explanation.
Another is chance. Now, no one would seriously propose that a single life-permitting universe just exists by chance. We’ve seen how precise all these constants have to be to allow for life in a universe. But some suggest that our universe is just one of many universes emerging from a higher-dimensional multiverse (called the Many Worlds or World Ensemble Hypothesis). Some have illustrated the multiverse as being like an ocean, with bubble universes that arise out of the sea from time to time. Some scientific theories, like superstring theory, predict this, but since the prediction can’t be tested — science is only capable of investigating this material universe — it remains only speculation. It has no more scientific merit than any spiritual belief. That doesn’t mean it is definitely false, but the multiverse is definitely a philosophical belief, not a scientific one.
And even if the multiverse does exist, this doesn’t provide a full explanation, either. Any multiverse capable of generating universes with life-permitting laws and constants would itself have to be very finely tuned. Collins compares it to a breadmaker. A breadmaker is capable of making all kinds of bread, but it needs the right kind of ingredients inserted, in the right proportions, before it can make anything. So even if a multiverse explains why the universe is so finely-tuned, you then have to explain why the multiverse is so finely-tuned.
The best explanation: Design
So we turn to the third explanation, and the one that seems to me clearly superior: Design. A timeless, spaceless, immaterial being wanted to create a universe, and he wanted to create living creatures to inhabit it. Plenty of people disagree with this assessment, though. So before we conclude design is the best explanation, we need to address a few last objections.
Do we have it backwards?
Douglas Adams has compared the design hypothesis to a sentient puddle. The puddle believes that because it fits so neatly in its hole, the hole must have been made for it, when in fact the puddle formed to fit the hole. Maybe it’s not that the universe was designed for us, but we have adapted to the universe.
But this completely misses the point of the above illustration. When we speak of fine-tuning, we are not talking about alternate universes where creatures grow to be 50 feet tall or everyone lives underground. Nearly every possible universe is incapable of possessing coherent structures of any kind, much less living creatures. The very fact that we are living in a universe living creatures can adapt to is incomprehensibly improbable.
Then why so much wasted space?
Some have pointed out that the universe as a whole isn’t really that suitable for life. After all, life is only able to survive on a few isolated rocks scattered around the vast lifeless void. Wouldn’t a Designer have either made much more of the universe habitable, or made a much smaller universe?
This point makes sense if the Designer is like a dispassionate engineer, making a machine that runs as efficiently as possible. But some, like the writers of Scripture, portray God as a God who loves to create and put his glory on display through his creation (Psalm 19:1). If, instead of thinking of God as a machine-builder, we recognize God as an artist who loves to create, it is no surprise that we see such an incomprehensibly vast universe.
Why should we care about any of this?
Some have said that it doesn’t matter how fine-tuned the universe is — after all, if it weren’t, we wouldn’t be here to wonder about it! Not every improbable event needs an explanation. For example, as it stands now, the odds of a particular barn in rural New Hampshire being struck by lightning on September 15 at 6:00 pm are very low, probably on the order of 1 in trillions. But if it happens, no one would conclude that God had divinely directed the lightning.
But this is just escapist reasoning. John Leslie uses an illustration similar to this: Imagine you were in a foreign country and were arrested on some trumped-up drug charges, and brought before a firing squad of fifty expert marksmen at point-blank range. At the executioner’s command, they all fire. Once the deafening shots stop, you look up to find that you are still standing there, unscathed. Would you be satisfied with the explanation that all fifty of these expert sharpshooters just happened to miss from a few feet away? Or would you conclude there was some design behind it — that they had missed on purpose as part of some grander scheme?
Back to design as the best explanation
As you take one look back at the control room, with all of its settings and dials you don’t understand, it should be clear that this universe is no mere accident. The best explanation is that it was designed by a spaceless, timeless, incredibly powerful being, who wanted to create a universe where sentient creatures could live. That being would be God.
Questions for readers
Have you ever read a sci-fi story that postulated a scenario where one or more of the fundamental laws and constants of nature was altered? How was it portrayed in relation to the science described here?
Do you think the fine-tuning of the universe makes a convincing argument for design? What do you think are the strengths and weaknesses of this argument? Does it bolster your faith personally?
If you believe the universe was designed by God, and he intentionally created these laws and constants to such a precise manner, what does that say about how he works in each of our lives?
