Date: December 18, 2010

Title: Is There Cosmological Evidence for God?


Podcaster: Dr Stuart Clark


Description: Is the Universe finely tuned for human life? If so, is this cosmological evidence for God?

Bio: Dr Stuart Clark is an award-winning astronomy author and journalist. His books include The Sun Kings, and the highly illustrated Deep Space, and Galaxy. His next book is Big Questions: Universe, from which this podcast is adapted. Stuart is a Fellow of the Royal Astronomical Society, a Visiting Fellow of the University of Hertfordshire, UK, and senior editor for space science at the European Space Agency. He is also a frequent contributor to newspapers, magazines, radio and television programmes. His website is and his Twitter account is @DrStuClark.

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Hello I’m Dr Stuart Clark, astronomy author and journalist. Today I’d like to explore the question: Is there cosmological evidence for God?

In the course of his troubles with the Vatican, Galileo Galilei made a flippant comment that nevertheless carried weight. He said that the Bible tells us how to go to heaven, not how heaven goes. He meant that the Vatican theologians should not attempt to determine the workings of the cosmos by interpreting passages of the Bible. Only astronomy and rational thinking could reveal the way the universe ran, said Galileo, but that did not detract from the Bible’s role in leading humankind to the salvation of their fragile souls.

Since Galileo’s time, astronomy has frequently clashed with religion over whether God exists. Isaac Newton and Albert Einstein both had their parts to play in this debate. When Newton published his theory of gravity in 1687, he was attacked for promoting atheism because his theory explained just about all motion on Earth and in the universe, so where was there room for God? A religious man himself, Newton stated that his theory did not explain gravity, merely what it did and that perhaps God was to be found in the explanation of gravity’s nature.

Centuries later Einstein crowned this idea by saying that he could not believe in an interventionist god: one that is manipulating reality to create miracles, but he could believe that the laws of physics were an embodiment of God. At the time, many other scientists were busy trying to explain that the universe did not need a god at all; that everything could be understood in rational terms. Later in is life, Einstein seemed to join their ranks. He wrote in 1954, “The word God is for me nothing more than the expression and product of human weaknesses.”

These days there is a resurgence of discussion about whether the universe has been designed specifically for human life, implying a divine creator. Astronomers call it the ‘fine tuning problem’ because, as they have developed a greater understanding of the physical laws, so they have been able to investigate what the universe might have been like if the constants of nature had been a little different. To their surprise, they have found that the vast majority of possible universes do not seem hospitable to life.

Take for example the rate at which the universe is expanding. If the expansion rate had been faster than it is today, then matter would have been spread too thinly and the galaxies could not have assembled themselves in time. At the other end of the scale, if the expansion rate had been too slow then the universe would have collapsed back on itself already, before stars, planets and we had time to develop.

So, fine-tuning refers to the apparently slim range of physical constants that can give rise to life. This leads scientists to wonder why a universe with human life exists at all, given that it all so highly improbable?

The short answer is that no one knows. Some believe the question to be nonsensical because if the universe had not been like it is we would not be here to ask the question, so we might as well just accept it. Others believe that there must be a more profound reason: God made it this way. This latter view has resonance with the mindset of early nineteenth century naturalists.

By the early 1800s, human investigation had revealed the most amazing fit between the various life forms and their environments. It was thought to be clear proof that God had designed the world to be perfectly suited for the life it contained. Then in 1859, Darwin turned this thinking on its head by presenting his observations that life forms can change with each successive generation to adapt to their surroundings. Most of us now think that the planet and its environment are largely accidental and that life forms evolve by random trial and error.

Could the same be true of the universe at large – that the fine-tuning we see around us is some form of cosmic evolution? This is where the multiverse and M-theory comes in. If M-theory is correct, then every possible universe is tried out and so inevitably there will ones where human life is possible. Even if humans need a particularly narrow range of properties, all the highly improbably fine-tuning is inevitable because there are an infinite number of universes, all with different properties and laws.

In this view, there is nothing special about our universe and so no need for God, we just happen to exist in the universe best suited to us. But there is a caveat to keep in mind when discussing fine-tuning and its possible implications. Do we perceive that the universe is fine-tuned because we lack the imagination to envisage other possibilities?

The universe constantly takes us by surprise, presenting us with wonders that we have neither the wit nor the experience to anticipate. An excellent case in point is the detection of planets around other stars. We had assumed that the distribution of planets would follow the familiar one of our solar system: rocky planets close to the Sun and gas giants further out.

One team of astronomers was even busily collecting data but not analysing it because they were certain that they would need a decade of observations in order to see Jupiter-like planets in their long orbits. In fact, the first detected planets were indeed Jupiter-sized, but orbiting closer to their star than any planet orbits the Sun in our solar system. The information took us completely by surprise, showing us something we had thought was impossible.

Will the same be true for life? Could it be that other routes to life – though not necessarily human life – would be available with other constants of nature? Until we can define what life is and therefore have a concrete rule for what is and isn’t alive, the discussion of whether we live in a finely tuned universe is perhaps premature.

There seems to me enough wonder in the universe that we should be able to content ourselves with that for the time being. So much that we can see and study remains unexplained, and the closer we look at the universe, the more mysteries and the more wonder we uncover. Perhaps this is the pattern of physics forever; there will never be a theory of everything, just an infinite succession of finer and finer details. Or perhaps, the final all-embracing theory is just around the corner.

Either way, we should be interested in cosmology for the journey of discovery that it represents, and not for the ultimate answers that it may or may not deliver.

End of podcast:

365 Days of Astronomy
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