A hundred metres below ground, under the border between France
and Switzerland, scientists are travelling back in time to study
matter as it was in the first fractions of a second after the
beginning of the Universe. They are using the world's largest
scientific instrument to help reveal how this primordial matter
developed into the building blocks that form the great diversity
of the Universe today.
These scientists-many from the UK- are explorers, extending our horizons in time as well as space, in an attempt to answer one of the most fundamental of questions:
At CERN, the European laboratory for particle physics near Geneva,
the path of the world's largest particle collider beneath the border
between France and Switzerland.
The observations of astronomers imply that the Universe is
still expanding from an infinitely dense and energetic state,
after an initial 'hot big bang' some 15 billion years ago. But
how did the matter of the present-day Universe evolve from this
state? This is one of the major questions that modern research in
particle physics seeks to answer. High energy collisions of
subatomic particles can take us back in time to the forms of
matter that probably existed in the first fractions of a second
after the big bang. In this way studying matter at the smallest
of scales (subatomic particles) has become inextricably linked
with research at the largest of scales (the cosmos). The particle
physicists of today have joined forces with astronomers in
exploring the origins of the Universe-and in particular, the
origins of matter.
Each element consists of building blocks - atoms - unique to the element, but the different atoms can combine to form an enormous variety of compounds from simple water to complex proteins. Yet, as scientists first discovered towards the end of the 19th century, atoms are not the simplest building bricks ofmatter.
This picture of the atom stems largely from pioneering work at Cambridge and Manchester Universities. At Cambridge in the 1890s, two physicists began unwittingly to probe the world within the atom. One, Joseph ('J.J.') Thomson, discovered the first known subatomic particle, the electron, while one of his students, Ernest Rutherford, started to explore the new phenomenon of radioactivity, in which atoms change from one kind to another. This was to lead Rutherford eventually to the discovery of the atomic nucleus, in work with Hans Geiger (of Geiger counter fame) and Ernest Marsden at Manchester University in 1909-10. Later, Rutherford found that atoms contain positively-charged particles, identical to the nucleus of hydrogen. He called the particles protons. And at Cambridge in 1932, James Chadwick showed that the nucleus must also contain neutrons. By this time Rutherford and his colleagues had established much of the modern picture of the atom.
The first observation of a
positive Kaon by Clifford Butler and
More Information
These scientists-many from the UK- are explorers, extending our horizons in time as well as space, in an attempt to answer one of the most fundamental of questions:
Where do we come from?
At CERN, the European laboratory for particle physics near Geneva,
the path of the world's largest particle collider beneath the border
between France and Switzerland.
A Brief History of Particle Physics
During the past two centuries, scientists have made great progress in understanding what we and the world about us are made of. First came the realisation that matter consists of basic substances, or elements, with well defined physical and chemical properties. These elements range from hydrogen, the lightest, through to uranium and beyond.Each element consists of building blocks - atoms - unique to the element, but the different atoms can combine to form an enormous variety of compounds from simple water to complex proteins. Yet, as scientists first discovered towards the end of the 19th century, atoms are not the simplest building bricks ofmatter.
Discovering the Nucleus, Geiger and Rutherford at Manchester University.
We now know that most of the mass of an atom is concentrated in a small, dense, positively-charged nucleus. A cloud of tiny negatively-charged electrons envelopes the nucleus, but at a relatively large distance, so that much of the volume of an atom is empty space. In most atoms the nucleus contains two types of particle of almost equal mass: positively-charged protons and electrically neutral neutrons. To make the atom neutral overall, the number of protons exactly balances the number of electrons.This picture of the atom stems largely from pioneering work at Cambridge and Manchester Universities. At Cambridge in the 1890s, two physicists began unwittingly to probe the world within the atom. One, Joseph ('J.J.') Thomson, discovered the first known subatomic particle, the electron, while one of his students, Ernest Rutherford, started to explore the new phenomenon of radioactivity, in which atoms change from one kind to another. This was to lead Rutherford eventually to the discovery of the atomic nucleus, in work with Hans Geiger (of Geiger counter fame) and Ernest Marsden at Manchester University in 1909-10. Later, Rutherford found that atoms contain positively-charged particles, identical to the nucleus of hydrogen. He called the particles protons. And at Cambridge in 1932, James Chadwick showed that the nucleus must also contain neutrons. By this time Rutherford and his colleagues had established much of the modern picture of the atom.
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