11 Responses to Fine-Tuning, from cosmologist Luke Barnes

This is a brief summary of the interview with cosmologist Luke Barnes, from  commonsenseatheism.com

1. Could the fine-tuning just be a coincidence?

It would be an amazing coincidence; maybe when all scientific knowledge is finished, we may want to consider that as a possibility.

2. We only have one universe to observe, so the chances of a finely tuned one is 1:1

Probabilities are about finding out what's probable from among what's possible. If Dawkins sees stars above his house written by God, and then says "Well there is only one universe, so the probability of those stars being arranged like that is 1:1.” Clearly, this is not a good answer.

3. Life can adapt to many different environments

If the fine tuning were off by just a bit, matter would collapsed into black holes, or the only stable element would be hydrogen, or the universe may have not expanded at all. There wouldn’t be molecules or even elements at all in the first place for life to be built from.

4. There could be other forms of life, based on silicon for example

Imagine a vast sheet of paper with a few pencil dots on it.The pencil dots represent life-permitting universes. If silicon can be stable enough to form life, then carbon can as well. And so having life based on other elements would be like putting a tiny pimple attached to some of the pencil dots.

5. Of course the universe is fine tuned, otherwise we wouldn't be here.

This is the anthropic principle. What if you asked why quasars are so bright, and someone answered “Well if they weren't so bright you would not be able to see them.” It explains why we don't see non-life-permitting universes, but doesn't explain why we do observe life-permitting ones. It's not the sort of explanation we are after; we need a causal explanation.

6. It's not possible for the universe to be any other way. Physical  necessity.

Other universes are logically possible. If the fine tuning is built into the theory of everything, then this just makes the problem worse because now the fine tuning is built into the very fabric of reality itself.

7. Perhaps there is a large number of universes

The multiverse is a good naturalistic option. But it’s not completely unproblematic. For one thing, the multiverse would have to be fined tuned as well; if you have a bad toaster, it will still spit out nothing but bad toast. Also, the probability of a finely-tuned universe even on the multiverse view is so great that we are more likely to be a Boltzmann Brain than a real universe.

8. Someone in the next universe up created this one

Then that universe would have to be fine tuned. It just moves the problem up a step.

9. Someone has to have a poker hand. Each is just as unlikely as any other.

Whenever I deal, I get a royal flush. Ten times in a row. Any set of ten poker hands is unlikely. Much of probability is about asking the right questions. "If this universe was chosen at random, then what is the probability of it supporting life?" is the wrong question.

The right question is "This universe is right for life; what is the probability that it was chosen at random?" So this objection fails.

10. The universe was not designed for life, but rather for vaccum or black holes

PZ myers asks why the entire universe couldn't just be lakefront property, but if it were, then it would collapse in on itself from gravity. The universe has to be big and sparse so that it expands and lasts a long time; any deviation from that and the universe would not exist at all.  This objection also misses the point.

Analogy: lets say we asked about all the possible ways that you could assemble two tons of metal and plastic. Of all the possible ways of arranging that metal and plastic, the set of functioning cars is very small. Could you refute that claim by saying "But your car doesn't go very fast!" Obviously not. It's a wrong-headed objection.

11. God

Isn't 100%, but it could be seen as making theism more palatable than naturalism.

What about God of the gaps?

God of the gaps applies to stuff in the universe, but fine tuning is about the stopping point. If naturalism is true, then this is just the way it is and you have to just take it as brute fact.

The designer is mysterious, so how does it explain anything?

Think of the cheating poker player. You would have to have some estimation of the prior probability that I would cheat. Even if we don't know you, we would still have to conclude that you ARE in fact cheating. Because even if you don't know me, it is up against the incontrovertible evidence that I am cheating.

Fine Tuning

Preliminary: The universe has several physical constants that are arbitrary and must be set exactly like they are in order to permit the development of intelligent life. The speed of expansion, the gravitational constant, the amount of entropy, etc. If a single one of them were even slightly different (or, alternatively, the range is very, very narrow), life in any form, not just as we know it, could not exist. They are unrelated to the laws of nature, which would always hold no matter what the constants were.

1. The fine-tuning of the universe is due to either physical necessity, chance, or design

Support: Seems to exhaust all the possible alternatives.

2. It is not due to physical necessity

Support: On the face of it, there is no reason why the expansion of the universe could not have been a little faster or a little slower, or the amount of entropy couldn't have been a little more or a little less. The best candidate for a Theory of Everything is string or M theory. But it does not predict the existence of our universe. It allows the existence of a large number of universes, but nothing about it uniquely predicts our universe and its constants. Hawking agrees.

3. It is not due to chance

Support: The chances are inconceivable that our universe should be life supporting.

Objection: Any particular universe is equally improbable. If it didn't happen, then we would not be around to see it. Response is to imagine a billion billion billion black balls (the number of non-life-permitting universes) and adding one white ball to it (the life permitting universe). Now pick out one ball, and it's the white ball. The chances against that happening are so high that it's almost impossible.

Objection: We could be living in a Multiverse (as proposed by Vilenkin), with a large number of universes parallel and so the chances are greatly increased. Response is that on the Multiverse model the universe is in a state of complete entropy already, and we are just a random fluctuation of energy within the entropy. But in that case we should be in a much smaller universe, or more likely a single brain (Boltzmann brain) and hence, solipsism is true.

Objection: The anthropic principle says that if observers evolve in a universe, then it is highly probable that they will witness a universe that is fine-tuned just for them. Response is that the anthropic principle says that it is highly probable observers will witness a universe fine-tuned for them, but it doesn't address that it is highly improbable that such a universe should exist at all.

4. Therefore, the fine-tuning of the universe is due to design

Support: From 1, 2, and 3.