Search

To a physicist, life seems little short of miraculous–all those stupid atoms getting together to perform such clever tricks! For centuries, living organisms were regarded as some sort of magic matter. Today, we know that no special "life force" is at work in biology; there is just ordinary matter doing extraordinary things, all the while obeying the familiar laws of physics. What, then, is the secret of life's remarkable properties?

If you are an academic in a physics department, you are probably used to receiving letters from people who claim to have rewritten the laws of physics. Editors of science magazines are also familiar with such individuals, many of whom take gravity for their victim. Although we should not automatically dismiss these ideas – after all, Einstein was an unknown patent clerk when he rocked the world of physics in 1905 – most fall down because their proponents fail to put them in context with existing knowledge.

In A classic understatement, Paul Dirac once remarked to the Royal Society that "the underlying physical laws necessary for the mathematical theory of...physics and the whole of chemistry are thus completely known, and the difficulty is only that...these laws lead to equations much too complicated to be soluble".

Physical laws such as the Schrodinger equation or Newton's laws explain many simple phenomena, from the quantized energy levels in a hydrogen atom to the motion of planets around the Sun. More complicated systems, such as a gas of atoms, can be studied by treating them as a collection of weakly interacting parts which are themselves simple This is reductionism.

Those reading this magazine will pay absolute homage to the so-called "laws of physics". There may be interesting divisions over the exact interpretation of quantum paradoxes, but "classical physics" would find us mostly united. There is, however, one area of human endeavour in which the laws of physics come under routine and flagrant violation. I refer to sport, and in particular the football field.

You could be a battle-hardened space marine or a medieval adventurer cutting swathes through dark hordes. But one thing is certain: you are going to have to obey the laws of physics, because even the best heroes feel the force of gravity on a planet's surface. As computer games get ever-more sophisticated, it is therefore no surprise that implementing the laws of physics realistically is becoming increasingly important for a high-quality "gaming experience". This is certainly good news for physicists who fancy trying their hand at games development.

In his review of Alex Rosenberg's book The Atheist's Guide to Reality (May pp42–43) Vlatko Vedral asks "What possible evidence can we have for other universes with other laws of physics?".

If you think science is a smooth progression towards objective truth then a dispute in the normally cordial world of optics research might make you think again. The disagreement concerns one of the most fundamental and best-known phenomena in optics – refraction. One set of researchers believes that a certain class of materials can refract light rays "negatively" and that these materials could be used to make "perfect lenses". But others think that negative refraction defies fundamental physical laws. Although it is unclear which view is correct, one thing is certain: neither side is going to give in without a fight.

The momentous complexity of modern physics is often seen as a stumbling block whenever one is asked to explain to the wider public – or to new students – how beautiful all of it is, and how unique and compelling are the logical deductions that have led to our present understanding. Many theoretical physicists have tried to do exactly this: to convey to the public not only what their findings are, but also why they think these findings are startling, and how these appear to reveal some deep underlying unity in the laws of physics.

Video-game enthusiasts who are usually disappointed by unrealistic physical effects should be delighted with a new game that claims to take into account the actual mass and density of buildings for the first time.

For centuries the solar system has been a source of inspiration for ideas relating to the physics of gravity and inertia. It has also provided an important test bed for new concepts and theories. Kepler's descriptive laws of planetary motion, for instance, led to Newton's discovery of the physical laws governing such massive objects, and the anomalous precession of Mercury's orbit was the First successful test of Einstein's theory of general relativity. As our astronomical horizons have expanded, however, we have looked beyond our solar system, and today it is the realm of galaxies and cosmology that provides the main testing ground for new ideas. And the first evidence for the existence of gravitational radiation was provided by studies of a binary pulsar.

The relationship between science and religion is a subject that many scientists have strong views on. Some believe there is simply no such thing as God. Others think that religion is legitimate because it answers different types of question to science. For physicist Frank Tipler, however, science and religion have much in common - in fact he believes that the laws of physics can prove the central tenets of Christianity.

Everyday experience tells us that it is impossible to travel backwards in time, no matter what science-fiction writers and movie directors tell us. However, this seemingly natural impossibility is actually one of the greatest mysteries in physics. Currently most physicists associate the irreversibility of time with the production of entropy in the warm macroscopic world. One consequence of this irreversibility – often called the "arrow of time" in thermodynamics is the ageing process. In plain terms, one grows old because of the irreversible physical processes that occur during one's life. However, the fundamental classical laws of physics discovered by Galileo, Newton and Einstein do not distinguish between the future and the past. In other words, they appear to be symmetric in time.

The universe, it is widely agreed, started with a Big Bang approximately 15 billion years ago. Much of what happened between then and now is pretty well understood: the universe expanded in a manner dictated by the laws of physics and a handful of cosmological parameters to create objects as dazzling and diverse as supernovae and supermodels. Today, quantum mechanics provides an extremely accurate description of what happens on the microscopic scale, while general relativity explains how the world behaves over much larger distances.

The physicist and popular-science writer Paul Davies has been appointed director of a new multidisciplinary research institute that will tackle a range of fundamental questions in physics. The institute, which he dubs a "cosmic think tank", is based at Arizona State University (ASU) in the US. It will examine questions such as the origin of the universe, the nature of the laws of physics, and the possibility that there exist other forms of life.

Newton's laws of motion are symmetric when time is reversed. The introduction of relativity and quantum mechanics does not change the situation. Yet in the world we observe, which we like to think is governed by the basic laws of physics, the asymmetry in time is very evident.

Jan-Henrik Andersen, a designer from the University of Michigan in the US, has The superhero Mighty Thor has an unusual way of getting airborne. He twirls his Uru hammer at tremendous speed, throws it aloft, and then grabs hold of it again?a manoeuvre that lifts both him and the hammer up. That series of actions may work in a comic, but surely it violates the conservation of momentum? Not necessarily, according to James Kakalios, a solid-state physicist at the University of Minnesota and author of a new book The Physics of Superheroes (2005 Gotham Books).

Every physics teacher recognizes the look of astonishment that appears on a student's face when they are taught special relativity. The first tenet on which the theory is built goes along with common sense: the laws of physics are the same in all inertial or non-accelerating frames. Billiards, for example, can be played on a steady cruise ship just as well as it can be played on solid land.

Every 18 months the number of transistors that can be packed onto a typical computer chip doubles. This is Moore's law – an empirical demonstration of our ingenuity to develop faster computers. Moore's law has held for the last 50 years, and if it holds for another 10 to 20 years then we will have created transistors that are the size of atoms. At this scale the classical laws of physics break down and are replaced by quantum mechanics.

"There are always explanations as to why the world has three dimensions. Well, there is only one world, and it is hard to tell if any particular explanation is right or not...". Richard Feynman in The Character of the Physical Law (1965) took the example of the world's physical dimensions to show what a theory should not attempt to address. Yet this is precisely the subject of this book by string theorist Michio Kaku, now at the City College of the City University of New York. But let's start at the beginning.

The Solar System has always been the paradigm of regularity and predictability. The foundations of dynamical astronomy are based on our attempts to understand the motion of the Sun, planets and satellites against the background of fixed stars. Newton's demonstration that Kepler's empirical laws of planetary motion arise from an inverse square law of force proved to be a cornerstone of mathematical physics. His work, and that of Laplace, helped to instill the belief that in order to understand and predict the behaviour of the world around us, all we had to do was discover the physical laws that governed the Universe. Since the motion of Solar System objects was ruled by deterministic laws, accurate measurements of the orbits of the bodies at a particular time would allow us, in principle, to calculate their positions at any arbitrary time in the future.

A few years ago, several groups of scientists around the US set out to establish interdisciplinary institutes that combine the expertise of physicists, chemists, biologists and computer scientists in hope of learning how the fundamental laws of physics guide living organisms. Now, the "science at the borders" programmes established at Princeton, Harvard, the University of Chicago, Stanford, the Howard Hughes Medical Institute (HHMI) and the University of California are starting to bear fruit in the form of new collaborations, curricula and buildings.

Turbulence, a problem of classical macroscopic physics, has received renewed attention of late as a subject whose understanding can shed light on the fundamental physical laws governing systems. Turbulent fluid motion exhibits such a higher degree of complexity and unpredictability that it has been considered essentially random. On the other hand, experimental evidence suggests that a remarkable degree of coherence is also present. It is precisely this subtle mixture of order and disorder that lies at heart of the difficulty in achieving a comprehensive theoretical description. While some analytical approaches have succeeded in describing the mean properties of the disorder, the lack of a characterization of key dynamic and static features of the coherence (structures) has prevented a deep understanding of physical processes involved in turbulence dynamics.

No-one who was lucky enough to have seen the Sun's corona during the recent eclipse could forget the prominences, tinged with red, that clung to the edge of the dark disc, or the streamers that extended outwards into space. These features are all caused by magnetic fields generated deep inside the Sun. However, the origin of these fields poses a major problem for classical astrophysics. Although the physical laws that describe the fields are known, the governing equations cannot be fully solved. A combination of new developments – both observational and theoretical – does, however, offer hope of rapid progress in the new millennium.

What lies behind the world we observe? Why are there laws of physics? Is there a need for a designer? Why does mathematics work? Why does physics work so well? How far can science go in deciphering the Universe? Will we, one day, know everything?

I have, out of curiosity, been trying to find out what long magnetic catapults are, but without success. Milton A Rothman, an ex-Princeton University plasma physics researcher, says with reference to "Methods of space propulsion" in The Laws of Physics (a Pelican Original, 1966): " ... take-off must be straight up (to get out of the air as quickly as possible), and it rules out acceleration by long magnetic catapults. (This last idea is not impossible for take-offs from the moon, where there is no atmosphere and where the escape velocity is only about 1.4 miles per second.)"

Few scientific puzzles have excited such enduring controversy as the problem of the 'arrow' of time. With a single minor and obscure exception, the laws of physics as we find them in the textbooks are time symmetric. The physical world, however, displays a pervasive unidirectionality in time. How can these two facts be reconciled?