Eyes to the sky for holy thought

There is within our nature an association between awe or respect and what is above. As children, we "look up" to our mother and father. To be seen better by a throng of people, a teacher, leader or hero must be at some height above our heads, so we put a priest in a pulpit, a politician on a stage and a hero on a pedestal. In church, the image of God or His symbol stands on a raised altar.

It is not surprising, then, that we feel that God, the ultimate being to be respected, is somehow associated with the astronomical universe that passes overhead. Cosmologists are widely felt to read (and sometimes themselves feel that they are reading) the mind of God.

Albert Einstein used such language to express his perceptions of space, time and the universe. "Tricky is God, but malicious he is not." "I shall never believe that God plays dice with the world." "I want to know God's thoughts."

Einstein's religious aphorisms seem to have arisen from a deep religious feeling, although he rejected conventional religions.

"God's equation," claims Amir Aczel, continuing Einstein's trend of thought, is the so-called Field Equation that Einstein crafted to describe the structure of the universe. Aczel describes how Einstein interacted with predecessors, colleagues and rivals to build up the Field Equation from general principles. For example, Einstein described the universe in the Field Equation only in terms of its radial structure, assuming that the universe looks the same in every direction but changes with distance.

The Field Equation at first contained the same problem that Newton discovered, that the effect of matter in the universe is to make the universe tend to collapse in on itself because of the attractive force of gravity. Einstein introduced a conjecture into the Field Equation that has the effect of a repulsive force. This term, which incorporates the so-called cosmological constant, stopped the universe from collapsing.

When Edwin Hubble discovered the expansion of the universe, the cosmological constant was no longer needed: the outward expansion is overcoming self-attraction, and the universe will not collapse for some time, if at all. Aczel describes how in 1998, astronomers discovered evidence implying that the repulsive effect of the cosmological constant really exists. "There is some funny energy in the universe," which is gradually released and accelerates the galaxies as they expand into space after the big bang.

Aczel's book is a clear description of how Einstein, by assembling a set of assumptions about the universe into mathematical form, discovered one of the most remarkable properties of space - that space is not "nothing". The vacuum is a physical state that releases energy. Aczel handles the story by moving easily between the general mathematical properties of the equations, their development and stories about mathematicians. Whether what resulted is mathematics, science or religion is less important than what was discovered. If it is confirmed, the discovery of the large-scale effects of vacuum energy will be one of the most important of the closing years of the 20th century.

Paul Murdin is head of astronomy, Particle Physics and Astronomy Research Council.