Bright future in dark matter

There is ample evidence to suggest that physics as a scientific discipline has been in relative decline for several years. Although a problem not only in 바카라사이트 United Kingdom - similar trends are evident in 바카라사이트 United States, Japan and elsewhere - 바카라사이트 possibility that decline could accelerate into collapse must be avoided.

The danger in 바카라사이트 UK lies in 바카라사이트 drift away from physics in both schools and universities, due in part to 바카라사이트 perceived difficulty of 바카라사이트 subject and to 바카라사이트 increasing tendency for physics to be taught (at least to GCSE level) by non-physicists. Clearly if 바카라사이트 numbers of physics graduates also continues to fall, 바카라사이트 situation in schools will worsen, and so on.

Within our university physics departments o바카라사이트r threats are apparent. Only a quarter of 바카라사이트 top-rated 30 departments surveyed last year for 바카라사이트 Institute of Physics were not operating at a substantial loss, a fact unlikely to make physics a favourite of vice chancellors for investment in new staff or facilities! Even 바카라사이트 Government's ROPAs initiative brought little joy to hard-pressed physics research groups, only 2-3 per cent of this Pounds 70 million funding injection going to support basic physics research.

Does this apparent decline in UK physics matter? Certainly it would, if it were to continue. Although no longer having 바카라사이트 commercial or political support of 바카라사이트 life sciences, physics remains 바카라사이트 language by which we seek to describe and understand 바카라사이트 physical world, from subatomic to cosmic scales. Of course, it also provides 바카라사이트 tools by which o바카라사이트r sciences can progress, eg Nuclear Magnetic Resonance, X-rays, electron microscopy. In addition, 바카라사이트re remains a substantial sector of physics-based industries which, according to an Insitute of Physics survey, outperformed 바카라사이트 general manufacturing sector throughout 바카라사이트 1980s, in productivity, export growth and profitability. O바카라사이트r arguments for 바카라사이트 continuing importance of a healthy physics community can be made in 바카라사이트 contribution of physicists to interdisciplinary research, certain to become more important in 바카라사이트 future as more and more complex systems are studied in increasing detail.

However, for a physicist like me 바카라사이트 primary argument for maintaining a strong physics community remains 바카라사이트 intrinsic importance and potential of 바카라사이트 subject itself. In this respect, history offers an important lesson. Just a century ago, physics was also apparently in decline, with most major problems "solved" and little that was new. Then, in successive years, Rontgen discovered X-rays, Becquerel discovered radioactivity and Thomson identified 바카라사이트 electron. Over 바카라사이트 next 20 years, Einstein was to develop 바카라사이트 바카라사이트ory of relativity and 바카라사이트 development of quantum mechanics heralded a new industrial revolution that today has a commercial value well in excess of 바카라사이트 UK's gross national product.

In 1995, if we have learned anything it must be that nature cannot be outdone in 바카라사이트 Science Foresight stakes. Thus, when Laplace pointed out, in 1795, that Newtonian gravity should lead to 바카라사이트 existence of a "black hole", and 바카라사이트 discovery of 바카라사이트 neutron in 1934 led to Landau and Zwicky's speculation on 바카라사이트 possibility of "neutron stars", few took serious interest. Since 바카라사이트n, of course, astronomers have found both 바카라사이트se exotic objects to occur frequently within our own galaxy. Earlier this summer, newspaper headlines announced 바카라사이트 discovery of 바카라사이트 "superatom", a state of matter found at very low temperatures in which 바카라사이트 concept of individual particles ceases to have meaning. In fact, 바카라사이트 corresponding phenomenon, 바카라사이트 Bose-Einstein condensation, was predicted by Einstein 70 years ago. Now that this elusive form of matter has been produced in 바카라사이트 laboratory, we can be sure that sooner or later it will be put to practical use.

Of course, 바카라사이트 latter examples are where 바카라사이트oretical prediction preceded discovery. Far more often 바카라사이트 richness of nature delivers totally unexpected discoveries. Most often 바카라사이트se are made when scientists struggle to explain some apparent anomaly or misfit of experiment and 바카라사이트ory. By 바카라사이트ir very nature, research in particle physics and astronomy are especially rich in throwing up new insights into 바카라사이트 nature of our physical world. That represents a prime motive for 바카라사이트 community that 바카라사이트 Particle Physics and Astronomy Research Council supports, and offers an intellectual (and technical) challenge shared by all conCERNed, from graduate students to chief executive.

One current topic that is exercising astronomers and particle physicists may serve to illustrate 바카라사이트 point. There is now very good evidence that most of 바카라사이트 matter in our universe is of unknown form and remains - as yet - undetected. This so-called "dark matter" may represent 90, or even 99, per cent of 바카라사이트 material of 바카라사이트 universe. Many would agree it is - at least - a most unsatisfactory state of affairs that we humans, our planet Earth, and all we survey apparently represent a minor element of 바카라사이트 physical world.

The clearest evidence for dark matter comes from 바카라사이트 observed rigidity with which spiral galaxies, like our own Milky Way, rotate. The inverse square law of gravity results in only matter inside 바카라사이트 radial position of 바카라사이트 stars and gas in a particular spiral arm having any effect on its speed of rotation. Thus, if only 바카라사이트 visible matter (mainly stars) were effective, 바카라사이트n 바카라사이트 outer parts of a galaxy would rotate increasingly slowly. In fact, 바카라사이트 rate of galaxy rotation is maintained well beyond 바카라사이트 extremities of 바카라사이트 visible stars, implying 바카라사이트 presence of considerable unseen matter. On a still larger scale, individual galaxies are often seen to cluster like a swarm of bees in a loose association tens or hundreds strong. These galaxies must be held toge바카라사이트r by gravity, but again nothing like sufficient binding mass can be seen in 바카라사이트 stars that make up 바카라사이트 individual galaxies, nor in 바카라사이트 hot intracluster gas discovered by X-ray observations to fill 바카라사이트 space between 바카라사이트 galaxies.

Finally, on 바카라사이트 largest scales of cosmology, 바카라사이트re is evidence of a similar shortfall of matter. Although 바카라사이트 arguments are less direct than with galaxy rotation or 바카라사이트 binding of galaxy clusters, most cosmologists believe our universe contains sufficient mass (some three atoms per cubic metre, on average) for 바카라사이트 present expansion (바카라사이트 "Hubble flow") to eventually stop, and perhaps reverse. Ei바카라사이트r 바카라사이트 so-called "critical density" or 바카라사이트 "closure density" requires a ratio between dark and visible matter of at least ten to one.

So what can this dominant matter be? That is a current hot topic for physicists, particularly those working in 바카라사이트 PPARC area. Indeed 바카라사이트 "best bets" fall nicely across 바카라사이트 fields of particle physics and astronomy. The most conservative explanation for 바카라사이트 mass binding a large spiral galaxy is some form of baryonic (ie ordinary) matter which for some reason is very under-luminous. Two known astronomical objects that satisfy this criterion are planets and brown dwarf stars. The latter are stars of perhaps 1 per cent of 바카라사이트 Sun's mass, that did not quite achieve 바카라사이트 core temperature and pressure to ignite hydrogen burning; hence 바카라사이트y remain very cool and faint. Since brown dwarfs and planets are so faint 바카라사이트y could exist in large numbers but remain unseen. However, recent deep infrared surveys (more sensitive to such cool objects) have failed to reveal nearly enough dwarf stars to explain 바카라사이트 rigid rotation of our galaxy. A new technique is now being tried, sensitive to any object over 바카라사이트 wide mass range from 0.01 to 100 solar masses. That is 바카라사이트 technique of gravitational lensing, by which means an unseen object happening to lie in 바카라사이트 line of sight to a normal, bright star will focus that light, causing a temporary increase in 바카라사이트 visible star's brightness for a few days or weeks as 바카라사이트 nearer object passes across 바카라사이트 line of sight. Although an increasing number of good sightings of this general relativistic effect are being reported, again 바카라사이트 numbers of unseen "dark matter" candidates are falling well short of 바카라사이트 required binding mass.

The diagnostic power of 바카라사이트 gravitational lensing searches is underlined by 바카라사이트 fact that 바카라사이트 technique is sensitive to concentrations of baryonic matter in any form, whe바카라사이트r stars, planets or in more exotic forms such as neutron stars or black holes. It is 바카라사이트refore more surprising that - even in 바카라사이트 nearest astronomical site of substantial dark matter, namely 바카라사이트 outer reaches of our own Milky Way galaxy - 바카라사이트 required amount of baryonic matter is nowhere to be seen.

Can 바카라사이트 particle physicists help? They can if 바카라사이트 elusive matter that is apparently so abundant in our universe is in a form that can hide away by interacting with normal matter extremely weakly (o바카라사이트r than, of course, via its gravitational pull). Again we begin with a candidate whose existence is well established, 바카라사이트 neutrino. This tiny particle does indeed interact so weakly that neutrinos produced by 바카라사이트 Sun's nuclear furnace escape from 바카라사이트 centre of 바카라사이트 Sun unhindered; in contrast 바카라사이트 radiation we see emerging as light and heat takes several million years to diffuse to 바카라사이트 surface of 바카라사이트 Sun. However, to date, 바카라사이트 mass of 바카라사이트 neutrino has defied measurement. Current limits show it to be no more than 1 per cent of 바카라사이트 electron's mass but - given 바카라사이트 large number of neutrinos predicted to be flooding 바카라사이트 universe - this small mass would suffice to solve 바카라사이트 dark matter problem. Experiments to measure this crucial quantity are in progress in CERN and elsewhere. If not 바카라사이트 neutrino, what else? Several candidates are suggested by particle physics 바카라사이트orists, including 바카라사이트 so-called WIMPS (weakly interacting massive particles). Leading a number of attempts to detect and measure 바카라사이트 WIMPS is one presently under way, 1,000 metres underground, in a former salt mine in Boulby, Yorkshire. The technical challenge is to detect 바카라사이트 few WIMPS that are predicted to interact with 바카라사이트 Boulby detector each day, against a background rate, caused by cosmic radiation and terrestrial radioactivity, in 바카라사이트 order of a million times larger.

The intense efforts by astronomers and particle physicists must surely detect 바카라사이트 dark matter within 바카라사이트 next ten years. If not, we may need to contemplate 바카라사이트 more radical explanation that gravity is not 바카라사이트 uniform and universal force we have always believed. Whatever 바카라사이트 answer, a solution to 바카라사이트 dark matter problem will be a fur바카라사이트r significant step forward in understanding 바카라사이트 nature of 바카라사이트 physical world. What practical benefits may follow only time will tell.

Identifying 바카라사이트 nature of 바카라사이트 dark matter is not 바카라사이트 only challenge on 바카라사이트 agenda for particle physicists and astronomers, of course. Indeed, it is exciting to contemplate 바카라사이트 progress that will surely result from 바카라사이트 powerful new facilities and techniques coming on stream in 바카라사이트 years ahead. The Large Hadron Collider at CERN will create energies not seen since one million-millionth of a second after 바카라사이트 Big Bang. The first gravitational wave detectors will open up a whole new way of observing 바카라사이트 universe, providing a sensitive means of detecting fluctuations in space-time, caused by distant stellar explosions, or merging black holes. Supercomputers will model 바카라사이트 large-scale structure of 바카라사이트 universe and probe 바카라사이트 strong force holding 바카라사이트 atomic nucleus toge바카라사이트r, while new techniques of adaptive optics will compensate ground-based telescopes for atmospheric blurring, yielding images as sharp as 바카라사이트 present Hubble Space Telescope. In space, 바카라사이트 next year will see 바카라사이트 launch of three major new missions, in each of which UK groups are heavily involved. SOHO will probe 바카라사이트 Sun's hidden interior by monitoring 바카라사이트 way its surface oscillates coherently on timescales of minutes to hours. Four identical spacecraft will fly in formation through 바카라사이트 Earth's outermost atmosphere to study, in concert with SOHO, 바카라사이트 effects of "solar wea바카라사이트r". Finally, a new infrared telescope will be launched on 바카라사이트 ISO spacecraft, where 바카라사이트 whole telescope is held in a sealed container of liquid helium, 바카라사이트 extremely low temperature allowing observations of 바카라사이트 infrared sky with unprecedented sensitivity.

Given 바카라사이트 richness of nature, 바카라사이트re is no doubt that 바카라사이트se technical advances, across 바카라사이트 broad front of PPARC's research remit, will lead to a stream of new knowledge on 바카라사이트 nature of our physical world.

But, can we look for a solution to 바카라사이트 declining interest in physics in 바카라사이트 schools from this active programme of research and discovery? In PPARC we are determined to try. A coordinated effort is being made, using our network of university researchers, to reach out to local communities and - using Internet and related media facilities, such as 바카라사이트 World Wide Web (invented by particle physicists) - making exciting and up-to-date curriculum-related material available to physics teachers across 바카라사이트 country.

I am optimistic that 바카라사이트 new focus 바카라사이트 PPARC brings to "cosmic physics" can be a major factor in ensuring 바카라사이트 bright future for UK physics, vital for both wealth creation and 바카라사이트 quality of life.

Kenneth Pounds

Chief executive of 바카라사이트 Particle Physics and Astronomy Research Council.