How come our Universe was fine-tuned to enable the miracle of Life?
Consider Omega. Commonly known as the density parameter, it tells us how important gravity is in the expanding universe.
Two opposing forces are at play: the “expansion energy” blowing the Universe apart, making it fly away from itself at a tremendous speed ever since the Big Bang; and gravity, holding everything together to stop it separating so fast.
How powerful are these forces? The ratio between them is what’s called “omega”, and it’s approximately…1. That’s right: the two opposing forces, gravity and expansion energy, are almost equally powerful.
Why is this important? Well, it’s what keeps our Universe stable. If gravity were too strong, compared with dark energy and the initial metric expansion at the Big Bang, then the universe would have collapsed before life even had a chance.
You’d never be here.
I’d never be here.
And we wouldn’t even be able to feel sad about it.
On the other hand, if gravity were too weak, then its pulling force would be useless. No stars, including our sun, could have coalesced from swirling dust and gas clouds. Without anything to pull it into lumps, the universe would just be an almost empty space filled with wisps of dust-clouds.
Omega is one of twenty or so initial conditions and physical constants whose values are just right for life to have evolved. If any of them had been even marginally different, the birth of stars and planets would not have been possible. Life could never have gotten started — on Earth, or anywhere else.
Another example is the Hoyle State, the third lowest energy-state of a carbon-12 nucleus. It has an energy of 7.656 MeV (million electron volts) above the ground state level. According to one calculation, if the State’s energy level were just a tiny bit different — say marginally lower than 7.3 or a hint greater than 7.9 MeV — then carbon wouldn’t have formed in the quantities it has.
There could be no life, because there wouldn’t be enough carbon from which to make it.
One more example relates to the speed of light. Even a slight variation in the speed of light would alter the other constants, which are dependent on it. For example, Einstein’s formula, E=MC², for the conversion of mass to energy includes the speed of light, C. This relationship is important as it determines the amount of energy output from the sun, which in turn determines whether life-supporting conditions can exist on Earth.
Closer to home, the existence of large planets in the solar system also shows us the cosmic fine-tuning which supports life on Earth. If Jupiter were not in its current orbit, Earth would be bombarded with space material such as meteors and comets, rendering it uninhabitable. Jupiter’s strong gravitational field acts as a “cosmic vacuum cleaner” to attract space debris away from Earth.
The question is: how did this cosmic fine tuning come about? How is it that each of the values for the physical constants is so precisely tuned to the unique point, among countless possibilities, that allows us to exist?
A number of possible explanations have been put forward, some going back to biblical times. Here are are the five main contenders:
- It was just a coincidence that the Big Bang produced a universe with those values and initial conditions.
- God designed it that way.
- It was meant to be. The universe has a purpose: to enable life.
- In a multitude of universes, we were the one that ended up that way.
- It is an illusion. The universe we see is not real: we are in someone’s (God’s or an ET’s) computer simulation.
Which explanation is correct? We may never know. However, we can predict which explanation is most likely to be correct, if we only dig a little deeper.
Let’s start with the first theory, which contends that he Big Bang was a unique, random, chaotic event, with all the parameters free to be set to random values. And, purely through chance, we ended up having a universe with precise values that allow us to exist — rather than any of the countless other possible values available.
The problem with this theory is that, if the Big Bang were indeed such a unique random event, then the probability that the universe could have been blessed with a suite of those exact values, is vanishingly small.
Thus, we are required to accept that we exist due to an extremely unlikely coincidence. But since we are here, then that unlikely coincidence must have in fact occurred. This circular argument is somewhat unsatisfactory for those of you with a statistical bent; not to mention those of you who think that there must be a purpose to existence.
The second possible explanation is really about intelligent design: that God created a universe to enable life. This is an article of faith in many religions. It requires a belief in an invisible God whose existence is authenticated by scripture.
Even those not so religious, however, have a similar explanation to draw upon. Aristotle’s idea, which predated Christianity, was that everything has a purpose. For the universe, that purpose could have been to enable life; and its fine tuning was required in order for it to do so.
There are two problems with this approach. In the first place, it is somewhat anthropocentric. Surely our existence on this tiny speck of a planet could hardly be the focus of any purpose this vast universe might have? That is, unless we are not alone; that life is ubiquitous, but we cannot detect it because of the tyranny of intergalactic distance.
Secondly, to embrace this idea of a purposeful universe would mean accepting the teleological principle of final causes: that physical events are determined by the ends rather than the means. This dubious logic is like saying gravity exists because the apple needs to fall, rather than the other way around.
Rather, science is rooted in the principle of prior causes: it requires that a causal chain can be traced all the way back to the Big Bang, governed by the laws of physics, but still subject to the laws of probability.
You will have to decide for yourself whether to accept this teleology from a philosopher who lived 2,400 years ago. He just might have been one of the brightest people to have ever lived, though he was working in a scientific dark-age; sometimes he got things right and sometimes he got them wrong.
That we are just one universe in a multitude of universes is an explanation favoured by some cosmologists. This is because it provides a way, consistent with the laws of probability, for our universe to have ended up with values for its initial conditions and physical constants that it did.
There might have been an infinite, or near infinite, number of Big Bangs, producing the same number of separate universes, each in its own bubble which we cannot see. In such case, the chances of one such universe — ours — ending up with the right key values is much higher than if our Big Bang were the only throw of the dice, so to speak.
This explanation suffers from its reliance on the existence of a multiverse that is invisible, and which we cannot detect with our instruments — which may well be true, but then again, it may not.
The fifth hypothesis as to why our universe seems so fine tuned for life is that it is an illusion: that we are not in a real universe, but in someone’s computer simulation; and that the fine tuning could have been fabricated.
This explanation could only have arisen after the beginning of the computer age. It is based on the assumption that a technologically advanced civilization has developed computers so powerful that they are able to simulate the workings of your brain, senses and emotions, which is no mean feat on its own. In addition, they are also supposed to be able to simulate the complex historical, political, social, economic, artistic, scientific and technological achievements of humanity. This is not to mention the representation of all the other supposedly living things on the planet and the night sky which we see (or think we see) with our own eyes.
Because we are in a simulation, so the argument goes, we would not know it, and would not be able to see who or what was controlling it.
This advanced civilization that is supposed to be simulating our world on its supercomputer could have preceded us on earth (if such a planet really exists) or be in another planetary system somewhere else in the universe, or beyond. It may have even enabled a machine with artificial intelligence (AI) to operate the computer simulation and to control us humans. This would certainly be putting the shoe on the other foot.
That fanciful explanation for our fine-tuned universe should belong more in the realm of science fiction than in any serious inquiry. However, it owes its existence to the presence of boundless optimism among our AI community about the expected rate of progress in creating human intelligence and consciousness in a machine — “if we can do it, then so can they!”
This is partly due to the widespread belief in Moore’s Law, which until quite recently has accurately predicted that computer speed and capacity will double every two years.
This hypothesis requires you to believe that your life is unreal; that you live in a virtual world. Such an idea is likely to be at odds with what you feel in every bone of your body: that you exist in a real world and have control over your own life. In addition, to accept this hypothesis you would have to embrace the optimism of the AI researchers. It is not just science in which you have to believe, but also a vision of the future on the planet, which if realized by us, would support the contention that extraterrestrials could have beaten us to it.
A variation of this hypothesis, reminiscent of some religious beliefs, is that the person at the controls of the simulation is none other than…God himself!
In summary, a leap of faith is required to explain how our universe was fine tuned to enable life. We must either accept that our existence is some kind of fluke (the first explanation) or that it relies on a God whom we cannot see, or a purpose we cannot justify, or a multiverse we are unable to detect, or a technology we can only imagine. I leave it to you, the reader, to choose the explanation you prefer, or none of the above.
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