We have a basis for understanding the synthesis of elementary proteins. This is but the first rung on the ladder towards the evolution of life as we know it. As we climb this ladder, the system adapts itself more strongly to the terrestrial environment and so it is from here on that the divergences between […]
We have seen that the primitive atmosphere of the Earth would have contained, at a very early stage, organic compounds of varying degrees of complexity. Indeed, the picture described so far is likely to be a fairly common one wherever planetary systems have formed; no extraordinary events have been postulated. The next step must be […]
Given that other stars have planetary systems, what is the likelihood that the planetary system resembles our Solar System ? If we can answer that, we may be able to decide whether the evolution of life on Earth has any relevance to life elsewhere in the Universe. The only planetary system we have any knowledge […]
How likely is it that systems similar to the Solar System exist elsewhere in the Galaxy ? This, like many of the questions raised when discussing extraterrestrial life, is a highly controversial issue. It should be remembered that we have no direct evidence for the existence of any planetary system other than the Solar System. […]
Life is the most complex state of organization of matter known in the Universe. Living systems achieve this state of organization by using energy that they extract from their environment. Many physical systems do this, but a living system is distinguished in that it uses the energy to convert the material taken from its surroundings […]
A typical galaxy contains some hundred billion stars, most of which are not unlike our own Sun. The largest telescopes can photograph some billions of galaxies. The observable Universe therefore contains some 1020 stars! How likely is it that the Sun is the only one among these which is orbited by a life-bearing planet? This […]
In the past, MACH’S PRINCIPLE has been considered a central cosmological issue .Mach’s principle is an ill-defined concept but broadly speaking asserts that our local physical laws are influenced by the large scale distribution of matter. An often-quoted example that illustrates this is that of the Foucault Pendulum. If a pendulum is set up by […]
During these past fifty or so years, we have discovered our Universe and set it within the framework of the laws of physics. A concrete and coherent picture has emerged. This picture is indeed compel¬ling: there are few (if any) viable alternatives, and the theory has satisfied every test demanded of it. But is our […]
The picture described above provides one explanation of why the Universe may have become lumpy. We are, however, a long way m. from being able to verify such a theory by observation: galaxies ay bear few birthmarks that might provide rather indirect clues to their origins. It is not surprising, therefore, that cosmologists have been […]
Consider a small region of the Universe where the density of matter is slightly higher than elsewhere. The gravitational force holding this region together will be slightly greater than for comparable volumes elsewhere. Therefore, if gravity is the only force acting, the expansion of the overdense region will lag behind the expansion of the Universe […]