PAUL DAVIES

The birth of science as we know it arguably began with Isaac Newton's formulation of the laws of gravitation and motion. It is no exaggeration to say that physics was reborn in the early 20th-century with the twin revolutions of quantum mechanics and the theory of relativity.

The way life manages information involves a logical structure that differs fundamentally from mere complex chemistry. Therefore chemistry alone will not explain life's origin, any more than a study of silicon, copper and plastic will explain how a computer can execute a program.

Astonishingly, in spite of decades of research, there is no agreed theory of cancer, no explanation for why, inside almost all healthy cells, there lurks a highly efficient cancer subroutine that can be activated by a variety of agents - radiation, chemicals, inflammation and infection.

Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that NASA's budget is too small for the job.

An argument often given for why Earth couldn't host another form of life is that once the life we know became established, it would have eliminated any competition through natural selection. But if another form of life were confined to its own niche, there would be little direct competition with regular life.

Although the elusive 'cure' may be a distant dream, understanding the true nature of cancer will enable it to be better controlled and less menacing.

Perhaps the best motivation for going to Mars is political. It is obvious that no single nation currently has either the will or the resources to do it alone, but a consortium of nations and space agencies could achieve it within 20 years.

No planet is more earth-like than Earth itself, so if life really does pop up readily in earth-like conditions, then surely it should have arisen many times right here on our home planet? And how do we know it didn't? The truth is, nobody has looked.

Searching for alternative life on Earth might seem misconceived, because there is excellent evidence that every kind of life so far studied evolved from a common ancestor that lived billions of years ago. Yet most of the life that exists on Earth has never been properly classified.

A universe that came from nothing in the big bang will disappear into nothing at the big crunch. Its glorious few zillion years of existence not even a memory.

Imagine a civilisation that's way in advance of us wants to communicate with us, and assist us in our development. The information we provide to them must reflect our highest aspirations and ideals, and not just be some crazy person's bizarre politics or religion.

My feeling is that scientific method has the power to account for and interlink all phenomena in the universe, including its origin, using the laws of nature. But that still leaves the laws unexplained.

For me, science is already fantastical enough. Unlocking the secrets of nature with fundamental physics or cosmology or astrobiology leads you into a wonderland compared with which beliefs in things like alien abductions pale into insignificance.

It will be in the convergence of evolutionary biology, developmental biology and cancer biology that the answer to cancer will lie. Nor will this confluence be a one-way street.

Clearly, some creative thinking is badly needed if humans are to have a future beyond Earth. Returning to the Moon may be worthy and attainable, but it fails to capture the public's imagination. What does get people excited is the prospect of a mission to Mars.

Traditionally, scientists have treated the laws of physics as simply 'given,' elegant mathematical relationships that were somehow imprinted on the universe at its birth, and fixed thereafter. Inquiry into the origin and nature of the laws was not regarded as a proper part of science.

Should we find a second form of life right here on our doorstep, we could be confident that life is a truly cosmic phenomenon. If so, there may well be sentient beings somewhere in the galaxy wondering, as do we, if they are not alone in the universe.

Science, we are repeatedly told, is the most reliable form of knowledge about the world because it is based on testable hypotheses. Religion, by contrast, is based on faith. The term 'doubting Thomas' well illustrates the difference.

In the frantic search for an elusive 'cure,' few researchers stand back and ask a very basic question: why does cancer exist? What is its place in the grand story of life?

Scientists are slowly waking up to an inconvenient truth - the universe looks suspiciously like a fix. The issue concerns the very laws of nature themselves.

In science, a healthy skepticism is a professional necessity, whereas in religion, having belief without evidence is regarded as a virtue.

Man-made computers are limited in their performance by finite processing speed and memory. So, too, the cosmic computer is limited in power by its age and the finite speed of light.

Things changed with the discovery of neutron stars and black holes - objects with gravitational fields so intense that dramatic space and time-warping effects occur.

Cancer cells come pre-programmed to execute a well-defined cascade of changes, seemingly designed to facilitate both their enhanced survival and their dissemination through the bloodstream. There is even an air of conspiracy in the way that tumours use chemical signals to create cancer-friendly niches in remote organs.

When I was a student, the laws of physics were regarded as completely off limits. The job of the scientist, we were told, is to discover the laws and apply them, not inquire into their provenance.