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.
The development of artificial intelligence may well imply that man will relinquish his intellectual supremacy in favor of thinking machines. With oceans of time available for future innovation, there seems to be no reason why machines cannot achieve and surpass anything of which the human brain is capable.
People take it for granted that the physical world is both ordered and intelligible. The underlying order in nature - the laws of physics - are simply accepted as given, as brute facts. Nobody asks where they came from; at least not in polite company. However, even the most atheistic scientist accepts as an act of faith that the universe is not absurd, that there is a rational basis to physical existence manifested as law-like order in nature that is at least partly comprehensible to us. So science can proceed only if the scientist adopts an essentially theological worldview.
No attempt to explain the world, either scientifically or theologically, can be considered successful until it accounts for the paradoxical conjunction of the temporal and the atemporal, of being and becoming. And no subject conforms this paradoical conjuction more starkly than the origin of the universe.
If we're thinking about old civilizations, those that formed a long time ago and there were stars and planets around long before Earth even existed, then these are going to be towards the center of the galaxy. That is the place to look if you think there are ancient civilizations that have made beacons or some other way of attracting our attention.
We know that within the solar system is very unlikely there will be anything more advanced than microbial life, but if we think outside the solar system and then, the distances are, of course, immense, then there could be Earth-like planets with more advanced form of life.
Cancer is not something confined to human beings. It's found in all multi cellular organisms where the adult cells proliferate, so it's widespread in the biosphere. It's a phenomenon that is deeply related to the history of life itself, so by studying cancer I think we can illuminate the history of life itself and vice versa.
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 gravity is by far the weakest force of nature, its insidious and cumulative action serves to determine the ultimate fate not only of individual astronomical objects but of the entire cosmos. The same remorseless attraction that crushes a star operates on a much grander scale on the universe as a whole.
Until now, physical theories have been regarded as merely models with approximately describe the reality of nature. As the models improve, so the fit between theory and reality gets closer. Some physicists are now claiming that supergravity is the reality, that the model and the real world are in mathematically perfect accord.
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.
If you get a drill and drill down 5km beneath the ground, it's teeming with life - millions of tiny living fossils. They resemble the earliest life forms and suggest that life started under the Ground. The bible talks of Eden as a sunny parkland with white fluffy clouds, but it probably ascended from the region that we now associate with Hell.
No intelligent supervisor, no mystic force, no conscious controlling agency swings the molecules into place at the right time, chooses the appropriate players, closes the links, uncouples the partners, moves them on. The dance of life is spontaneous, self-sustaining, and self-creating.
The problem here is that a civilization that is 1,000 light years away doesn't know we exist. They don't know that we have radio telescopes here on Earth because they see Earth as it was 1,000 years ago. Nothing can travel faster than light, so however good their instruments they can't see in affect the future. So there is no particular reason they should be sending us messages at this time.
The temptation to believe that the Universe is the product of some sort of design, a manifestation of subtle aesthetic and mathematical judgment, is overwhelming. The belief that there is "something behind it all" is one that I personally share with, I suspect, a majority of physicists.
I should say we know that there are many, many other Earths out there. We're almost certain that there will be upwards of a billion Earth-like planets in our galaxy alone, so there is no lack of real estate where life might happen, but what we don't know is how likely it is given the real estate, given a wonderful pristine planet like Earth how likely is it that life will pop up inhabited? We don't know the answer to that.
We could tell them [alien civilization] things that we have discovered in the realm of mathematical physics, but there is stuff that I would like to know. There are some famous problems like how to bring gravitation and quantum physics together, the long-sought-after theory of quantum gravity. But it may be hard to understand the answer that comes back.
A permanent base on Mars would have a number of advantages beyond being a bonanza for planetary science and geology. If, as some evidence suggests, exotic micro-organisms have arisen independently of terrestrial life, studying them could revolutionise biology, medicine and biotechnology.
In spite of the fact that religion looks backward to revealed truth while science looks forward to new vistas and discoveries, both activities produce a sense of awe and a curious mixture of humility and arrogance in their practitioners. All great scientists are inspired by the subtlety and beauty of the natural world that they are seeking to understand. Each new subatomic particle, every unexpected object, produces delight and wonderment. In constructing their theories, physicists are frequently guided by arcane concepts of elegance in the belief that the universe is intrinsically beautiful.
The burgeoning field of computer science has shifted our view of the physical world from that of a collection of interacting material particles to one of a seething network of information. In this way of looking at nature, the laws of physics are a form of software, or algorithm, while the material world-the hardware-plays the role of a gigantic computer.
Supposing we knew that up there is some alien civilization and it's sending radio signals our way we should not tell the public where that is. We could say that we've picked up a signal, but we should not tell them where for the simple reason that anybody could commandeer a radio telescope, set themselves up as some self appointed spokesperson of mankind and start beaming all sorts of crazy messages back to the aliens.
Most research into life's murky origin has been carried out by chemists. They've tried a variety of approaches in their attempts to recreate the first steps on the road to life, but little progress has been made. Perhaps that is no surprise, given life's stupendous complexity.
In 1911 the little town of Nakhla in Egypt was the scene of one of the most remarkable events in historym when a chunk of rock fell from the sky and killed a dog. This is the only known canine fatality caused by a cosmic object. Improbably though this encounter was already, its truly extraordinary nature was revealed only decades later when scientists found that the culprit was not a common-or-garden meteorite, but a piece of the planet Mars.