Key to the Universe
|After years of confusion,scientists all over the world have reached a very exciting stage in their research into the basic ingredients of all matter. They say that the protons and neutrons at the heart of atoms are made up of elusive little things called quarks.In the diagrams on these pages Alec Nesbitt,the producer of Thursday's programme discusses quarks.Thirty - five year old Dr Stephen Hawking FRS,a scientist in the tradition of Einstein,is working to link these discoveries with his own research into "black holes" - despite grave physical handicaps.Overleaf he talks to John Hall.|
The Hunting of the quark
|Adding red,blue and green light makes white. There are believed to be three differently "coloured" quarks in the proton -so no colours are visible.|
|""When I use a word,"
said Lewis Carroll's
means just what I choose it to mean." Today's
high energy physicists have followed
Alice to a
land where familiar words like "colour", "strangeness" and "charm"
take on new meanings;and to a new looking glass-world
of opposites:"anti colours","anti strangeness" and "anti charm"
- in short,anti matter.
Early in the present century it was discovered that every atom had a nucleus of protons and neutrons with electrons buzzing around it.Then people began to ask : is the proton itself made up other particles? Gradually, a picture emerged of the proton as an assembly of much smaller objects, which were dubbed "quarks". Each proton, it seemed, was composed of three quarks, glued together in some way.
Bigger and bigger machines smashed protons to pieces and physicists searched among the flying debris for clues to the proton's composition.
|All sorts of unexplained
particles emerged,often to exist for less than a million-millionth
of a second before creating fantastic firework displays of more
familiar breakdown products. Eventually
many of these new particles were explained as combinations of quarks with
different properties, and these had to have names.
Two were called "up" and "down";and an ingredient of some of the more exotic particles became "strangeness".Many theories of how these fitted together were tried out.The most promising required a fourth quality - called "charm"*. The three-quark theory predicted that certain particles would break up in particular ways that simply did not happen. A fourth quark could explain these non-events. But the new theory also made a prediction - that charm (whatever it might be) would prove to exist.That set off the biggest hunt of recent years.
For a while, even as the "Key to the Universe" programme was being made, the search appeared in vain.
|Theorists began casting
around for alternative explanations.For a month or two of 1976
charm seemed about to meet the fate of Humpty Dumpty himself.But
then,within weeks,the whole picture changed dramatically,and already
Nobel Prizes have been handed out to the scientists who started the
chain of discovery.
The theorists needed the quarks in the proton to be different in other ways,too,and they chose colours.Colour one quark "red",the next "blue" and the third "green". Like a colour television,if you add red, blue and green light you get white, which is just as it should be, for the experimenters see no overall colour in the proton; yet it must be there, the theorists insisted, because some such quality is needed to provide the force that holds quarks together.
So how about the fourth quark - coloured lilac on our key? Physicists are split in their opinions about it. They're drawing up their lines for the next confrontation about that - again, it's the sort of fight that has Nobel Prizes for the victors.
|* It's perhaps worth noting that Hamilton required to add a fourth quantity to his number triples in order to get Quaternions to work.|
A few weeks ago members of the Relativity Group of the Department
of Applied Maths and Theoretical Physics at Cambridge sat down to commemorate
the 61st anniversary of the most important scientific finding of the century
- Einstein's general theory of relativity.They celebrated by upgrading the
cheese and pickle menu of their regular weekly meetings to include wine and
pate,they entertained guests from the Institute of Astronomy,and they whiled
away the luncheon hour by swapping thoughts on the agreed topic of "the
|At Fermilab,near Chicago,an international team led by Professor Burhop of University College London,set up a stack of photographic emulsion in the world's most powerful beam of neutrinos (shown here as a white line).From the heavy debris of a collision with nuclear matter a faint dotted track emerges.Nearly a hundredth of an inch long,it was made by a particle that survived for less than a million millionth of a second (shown here piercing the heart).From the manner of its creation and decay the scientists put strong odds on its containing a charmed quark.|
I think it is now generally accepted that this is, in fact
a black hole.
Hawking's most important early work was done in conjunction
with an Oxford theorist
Roger Penrose, was concerned with the nature
of the space-time singularities which occur at the centre of black holes.
These are points where the condensation of matter has reached such a degree
that an infinite density of material is contained in zero volume,and where
the known laws of physics break down.
Quantum mechanics and relativity theory. Quantum Theory
deals with the behaviour of matter at the sub-atomic level, while relativity
is concerned with space, time and the gravitational attraction between planets,
stars and galaxies.
He allows that his work may be an advance in the right
direction,but adds that he can't guarantee that it will be solved.
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