In recent days I have been asked on three separate occasions whether I think physicists are going to destroy the world the moment they switch on the Large Hadron Collider - the huge underground particle accelerator in Geneva - later this year. They ask if, as has been reported, the energies it will produce when beams of near light-speed subatomic particles are smashed together will create mini black holes that will swallow up the whole planet.

Add to this the more rational worries many people have about the global catastrophe of climate change if we don't act fast enough to curb our reliance on fossil fuels, or about GM crops producing Frankenstein food, hybrid embryo research producing Frankenstein babies, and nuclear power leaving future generations a legacy of toxic radioactive waste, and one is left with the impression that the average person is pretty scared about the rate of current scientific advances.

Of the above doom-laden list, the only issue I am unable to provide any sort of reassurance on is climate change, where I am just as worried as everyone else. The rest, I would argue, are based on unfounded fears arising from a misunderstanding of the science involved.

It is of course quite right that the implications - ethical or otherwise - of all manner of scientific research are high on the agenda of government decision-making and research funding. Science ethics is even being taught as part of new science curriculums in UK schools. While the issue of ethics in medical research has always been around, it can only be healthy that we are beginning to apply the same standards to other areas of science, not just so that scientists themselves think more responsibly, but to encourage them to explain what they do to the rest of society, particularly if they work in academia and are funded by public money.

For many, concerns with some scientific research are linked with the unease about living in a nanny state that they feel often passes through legislation and enacts policies without real consensual debate. So I would like to share with you what was, for me, a quite surprising example of the ultimate nanny state making some remarkably sensible decisions.

On a recent visit to Iran, I was allowed unrestricted access to the Royan Institute in Tehran where, by all accounts, world-class work in genetics, infertility treatment, stem cell research and animal cloning is carried out in an atmosphere of openness quite dramatically at odds with my expectations. Much of the work at the Royan is therapeutic and centred on infertility treatment. But their basic research in genetics was remarkably advanced, despite the restrictions on many of the researchers' travel to international meetings and the difficulties in publishing their work in the leading international journals.

What struck me most was the way the authorities overseeing the research seem to have dealt with the ethical minefields of parts of the work, in stark contrast with the howls of protest from some quarters in the UK in the run-up to the human embryo research bill that went through parliament recently.

At the Royan I spoke to one of the imams who sits on their ethics committee. He explained that every research project proposed must be justified to his committee to ensure that it does not conflict with Islamic teaching. Thus, while issues such as abortion are still restricted (it is allowed only when the mother's life is in danger), research on human embryos is allowed.

In this country the Catholic church has branded research on human embryonic stem cells immoral and says tinkering with life in this way is tantamount to playing God. So I was taken aback by the Iranian imam who pointed out, quite rightly, that all that is produced in this research is just a clump of cells and not a foetus, and so what was all the fuss about?

It is these stem cells that then differentiate into the specialist cells that are used to grow healthy tissue to replace that either damaged by trauma, or compromised by disease. Among the conditions that scientists believe may eventually be treated by stem cell therapy are Parkinson's disease, Alzheimer's disease, heart disease, strokes, arthritis, diabetes, burns and spinal cord damage.

The fundamental question is whether the original single zygote (the fertilised egg) is defined as a human being. If so, then it can be argued that it is morally wrong to destroy the embryo, as is done of course once the stem cells are harvested. Many in the Catholic church do indeed believe that the moment of fertilisation is also the beginning of human life - a notion not shared in Islam.

The embryo-is-a-human argument is based on the idea that the fertilised egg contains everything that is needed to replicate and that this is sufficient. But is this "potential" of becoming a human being really enough? I mean why stop there? Surely the unfertilised egg also has the potential of becoming a human, as indeed does each and every sperm cell (a notion immortalised in Monty Python's The Meaning of Life).

But I would argue that this is more than just a metaphysical issue. An embryo just a few days old is no more than a bundle of homogeneous cells in the same membrane, which do not form a human organism because they do not function in a coordinated way to regulate and preserve a single life. So while each individual cell is "alive", it only becomes part of a human organism when there is substantial cell differentiation and coordination, which occurs around two weeks after fertilisation. Until that time, for instance, there is still the chance that the embryo can split into two, to form identical twins. If each embryo develops into an individual person, how can the undivided embryo be said to have a separate existence?

Asensible definition of the beginning of human life is that it takes place sometime during the foetus's development. For many, both religious and non-religious, this is defined as when consciousness switches on. This crucial stage lies long after that of the embryonic stem cells with their "potential", rather it is when that potential is fulfilled. But too strong a link with consciousness can lead to the absurd situation of questioning the rights to life of a newborn baby if one subscribes to the view, held by some neuroscientists, that it is not really conscious.

According to Islamic teaching, I discovered, the foetus becomes a full human being only when it is "ensouled" at 120 days from the moment of conception, and so the research at Royan on human embryonic stem cells is not seen as playing God, as it takes place at a much earlier stage. Thus, while there is much that the west finds unpalatable about life under Islamic rule, when it comes to genetics they are not held back by their religious doctrine.

Like a number of other developing Islamic countries, such as Malaysia, Iran's scientific research is moving forward in leaps and bounds. I had hoped to visit one of its nuclear research facilities, but given the current political climate and Israel's threats of military action, it was no big surprise that my film crew and I were denied access at the last minute. Nevertheless, whatever criticisms we may have of the regime in Iran, I was left in no doubt that its researchers can hold their heads high. And we in the UK might learn a lesson or two from them before we complain too quickly about our own nanny state.

· Jim Al-Khalili is a professor of physics at the University of Surrey

j.al-khalili@surrey.ac.uk