Astronomer considers our cosmic habitat

Master of Trinity College and Emeritus Professor of Cosmology and Astrophysics at Cambridge University, former President of the Royal Society, peer of the realm and Astronomer Royal, Martin Rees enjoys stratospheric success. Earlier this year he received the Templeton Prize for his contribution to ‘enhancing life’s spiritual dimension’. He talks to Nigel Bovey.

Professor Rees, how did you become interested in science?

At school I was bad at languages so that made me move towards science and maths. Although I read maths at Cambridge University, I decided I didn’t want to be a mathematician.

I got a place to study for a PhD in science and was fortunate to have a supervisor who got me enthusiastic about astronomy, cosmology and space. It was the late 1960s and the subject was opening up rapidly. The good thing was that the subject was new to everyone so I didn’t need to be cleverer than the old guys.

In 1995 you became the Astronomer Royal. How did that happen and what are your duties?

The Astronomer Royal used to be the person who ran the Greenwich Observatory, which was established in the 1670s. Today it is an honorary title given to a senior academic in the subject. There are no duties. I don’t, for example, give the Queen her horoscope. The fact, though, that the title exists and there is no Physicist Royal or Chemist Royal indicates that astronomy was the first subject to become professionalised apart from medicine.

Astronomy goes back to the Babylonians and the need to have a calendar. I like to think of it as the first science to do more good than harm.

In your early work, when the big bang theory was less understood than it is now, you investigated phenomena such as red shift and quasars. How reliable is the big bang as an explanation as to how the Universe was formed?

Back to one second after the beginning of the Universe, I would say it is very reliable. When we look at distant objects we are looking back a long time and seeing the Universe when it was much younger. We see evidence that there was a time when the Universe was all squeezed so that everything was hotter than the centre of the Sun – which is ten billion degrees.

There are many ideas about what happened in the first fractions of a second but the conditions can’t be simulated and tested in the lab.

Did your work play a part in forwarding the big bang theory?

It has helped a bit but the main evidence against the alternative, the steady state theory, was found by radio astronomers at Cambridge. They discovered that when you looked far away and back in time, galaxies looked different and behaved differently. (In the steady state theory the population of galaxies would look the same everywhere and would not change.)

The most importance evidence for big bang was the discovery of cosmic microwave background radiation in 1965. This is the residual radiation from the beginning of the Universe and was the most direct evidence that in its very early stages the Universe was very dense.

In your book Our Cosmic Habitat you ask: ‘Could God have made the world any differently?’ Could he have?

I was quoting what Einstein said about God not playing dice with the Universe. What I had in mind was that one of the biggest issues in science is whether the laws of nature, which seem to pertain here, and indeed in all the parts of the observable Universe, are really the deepest level of existence.

An idea which has been taken more seriously in the past ten years is that the Universe may be a tiny fraction of physical reality. If there are other universes, would they all be governed by the same laws of gravity, electromagnetism and so on? Or are what we call the laws of nature just by-laws that apply only to our Universe?

What evidence is there that other universes exist?

There is no firm evidence. There will only ever be indirect evidence. In order to take a theory seriously you have to be able to test a lot of its consequences (but not every consequence). If we had a theory which applied to the first 10-36 seconds of big bang – the farthest back in time that scientists are postulating – and that theory applied to very high densities and energies and had quantities we could test in the lab, it might explain various mysteries in physics. We might then be able to apply it to cosmology and test whether there were a number of big bangs that formed a number of universes.

That’s a lot of ifs.

Absolutely. We are a long way from knowing. But if you ask physicists how they expect things will pan out, I think a high proportion would say ‘multiverse’.

In your book Just Six Numbers you describe how the Universe is shaped by just six mathematical relationships. If the numbers were even slightly larger or smaller, the cosmos would be very different and life on Earth impossible. Some people see such fine-tuning as evidence of God’s purposed Creation. Multiverse theory suggests that our Universe isn’t special, because it is one of a number that just happens to have got the maths right to sustain life. To what extent is the quest for a multiverse a way of finding an alternative explanation of origins to God?

I think the motive for people to think about the multiverse is simply to see if it is right or not and to understand the fundamental laws of nature. We are discovering new planets in our own Universe all the time, some of which may well turn out to be Earth-like.

To what extent would life on any of these Earth-like planets mean that life on Earth is less special, less purposed and less designed?

That would depend on what life were to be found. It may be that many of these planets have a biosphere like ours. It could also be that what has happened on Earth is unique.

There are two big uncertainties – how life gets started and how likely it is that evolution on another planet will lead to something as complex as life on Earth.

The astronomy is the easy bit – within the next 10 to 20 years we will know how many Earth-like planets there are. It will take a lot longer to answer the other questions.

How did life start on Earth?

We don’t know. One idea is that microbes arrived on a meteorite. Darwin talked about a warm little pond. Others talked about volcanic vents. Evolution can describe how life developed, but it doesn’t tell us how life came about.

Do you regard fine-tuning as a happenstance or is it evidence of design – the handiwork of a Designer?

We don’t know, but were I to put money on it, I’d bet on the multiverse idea.

With so many ifs, isn’t that a big punt?

There are lots of uncertainties, but that doesn’t mean that the multiverse idea is not a possibility.

Cosmologists and theologians, echoing Genesis chapter one, talk about the Universe coming ‘out of nothing’. Did it?

We don’t know. Before the first second, the science is incomplete. A physicist’s ‘nothing’, though, is not the same as a philosopher’s ‘nothing’. A physicist’s ‘nothing’ includes the laws of nature.

Are there questions that science isn’t designed to answer?

Science has made huge advances which add to our understanding of the world. I hope one day we will understand the origin of life and whether there is a multiverse. But there are many areas of life that are not part of science. Ethical choices, for example, can’t be decided by science.

Historically there have been conflicts between faith and science. To what extent is that inevitable?

There doesn’t need to be a conflict between faith and science. There are many good scientists who adhere to conventional Christian beliefs. Even among those who don’t, I think the majority would share the view that there need be no incompatibility.

Some atheistic scientists want to claim the theory of evolution as evidence that God wasn’t necessary for creation and therefore doesn’t exist – that evolution is effectively atheistic. Is that an accurate conclusion?

No, I think you can accept evolution and still adhere to a religion.

To what extent can science disprove God?

All science can do is to tell us what the world is like. Some things which were once considered mysteries and attributed to God are now understood.

Cosmology tells us that humankind is made of stardust. Could you explain the process, please?

Stars are like giant nuclear reactors, making chemical elements such as carbon and iron. In the very early Universe, stars were made of just hydrogen. Then, through nuclear fusion, hydrogen atoms fused to make helium, helium became carbon and so on. It is in the stars that the elements of the periodic table were made. At the end of their lives, stars exploded and the chemical elements made in stars went back into interstellar gas as nuclear waste.

New stars then formed from gas containing elements from the first generation, and heavier elements were formed. When those stars subsequently died, the process repeated.

There is very strong evidence that this process accounts for the proportion of all the elements in the Sun and our solar system – why gold and uranium are rare, and why oxygen and carbon are common.

When a star forms, it contracts from an interstellar cloud and it spins out. As it forms, there is the star and a spinning disc. What is thought to have happened is that when our solar system formed four and a half billion years ago, there was the Sun and a dusty spinning disc. As it spun, the dust particles stuck together to make rocks. They then built up to make the planets. The four terrestrial inner planets – Mercury, Venus, Earth and Mars – are the rocky ones. The outer ones were cold enough that they kept their hydrogen and helium and remained as balls of gas.

We know that the Earth has the same chemical elements as the Sun, just in different proportions. We know that the elements in the human body are the same elements as in the Sun.

All the atoms in our bodies were made in a supernova explosion that happened before the solar system was formed. All atoms are recycled within the Earth. They are not transmuted, so a carbon atom in my body was a carbon atom before the world was formed.

Science doesn’t know how the chemicals on a life-potential planet became the chemicals in our bodies, but there is a huge recycling process going on – dust to dust, ashes to ashes.

The concepts of dust to dust and humankind being made of dust appear in Genesis. To what extent does the idea of humankind being made of stardust show that faith and science are complementary?

Dust to dust is a biblical concept but it is also a sort of universal view. The idea of coming from and returning to nature is common to most people whatever their faith. A universal human predicament is that we are not on this earth for long.

What are the big challenges facing science?

The biggest challenge in science is not the cosmos or the micro world of the big bang but the complexity of the everyday world. The simplest animal is harder to understand than an atom or a star. Although I have evidence about the first second of the Universe or a distant galaxy, when it comes to issues such as diet, childcare or the environment the challenges facing the experts are far more difficult.

Science can explain the mechanisms of climate change – and the consequences of certain actions – but if you want to decide what we should do about it, either individually or as a society, you can’t make those decisions just on the basis of science. You need values and ethics that come from somewhere else.

Photo: Nigel Bovey

This article first appeared in The War Cry and is reprinted with permission