Visions of the Cosmos

 

Cosmology

The Ultimate Reality

Particle Physics

When a Man or Woman Sings

It's Strange to Think They're

Made of Strings

When a Little Doggie Barks

I'm Charmed to Think

She's Made of Quarks

And When Birds on High do Fly

Electrons Speed Them through the Sky

The purpose of this page of the web-site is to describe the nature of the world of particles and forces so far discovered and later to discuss the deepest question of all

WHY IS THERE SOMETHING AND NOT NOTHING?

The Structure of Matter

Our ordinary everyday world of matter consists of atoms in which electrons form orbitals around atomic nuclei.   Atomic nuclei are composed of protons and neutrons   It must be clearly understood that to-days Universe consists almost entirely of the matter particles protons, neutrons and electrons  (collectively called FERMIONS) and the carriers of the forces (collectively called BOSONS) which bind the matter particles together. 

These forces are:-

the electromagnetic force mediated by PHOTONS of a very wide range of energies and wavelengths.  (Gamma rays, X-rays, Ultra-violet, visible, infrared, microwaves, radio waves)

the so-called WEAK FORCE found in radioactivity,

 the STRONG FORCE which is of importance in the nucleus and in the nuclear particles protons and neutrons

the least understood and most mysterious force of all GRAVITY.

The nucleus consists of a number of tightly bound particles called protons and neutrons.  The number of protons in the nucleus is equal to the number of electrons and the electronic structure determines the chemistry of the specific atom.  Atoms are the very basis of the science of Chemistry and also of Molecular Biology.  The reader is directed to the section entitled ISOTOPES in the web-site which deals with the periodic table and with the isotopic forms of the chemical elements.

Chemical reactions are the most important phenomena in the ‘cold’ parts of the Universe such as planets.  We may not think of our planet Earth as cold when we think of the absolute zero of temperature or even the conditions on the moons of the outer planets such as Titan.  However by comparison with the stars it is very cold indeed and it is only under these low temperature conditions that chemical reactions are of supreme importance.

In the outer regions of stars some of the electrons are detached from the nuclei of the atoms – that is to say the atoms are ionized.  In the inner regions complete ionization takes place.  Atoms as such do not exist in these inner regions and therefore the temperatures are too high for ordinary chemical reactions to take placeThe electrons are no longer bound to the nuclei – a sort of electron/nuclei soup called a PLASMA exists.

In the core of stars nuclei still exist BUT at the very high temperatures in the core a new sort of chemistry begins to emerge – the nuclei begin to react together. We usually refer to the reactions between nuclei as THERMONUCLEAR REACTIONS.  The reader’s attention is drawn to the sections of this web-site dealing with ‘Our Star the Sun’, ‘Superstars and Supernovae’ and in particular ‘The Magic Furnace’.   Even at the colossal temperatures found in stars and even in the higher temperatures in supernovae the protons and neutrons within in the nuclei still remain intact and it was this fact that made many people think that they were fundamental particles just as the electron appears to be.  It is now known however that both these particles are composed of even smaller particles called quarks and gluons.  At the present state of our knowledge quarks and gluons do appear to be fundamental.   

It is now known that at energies and temperatures that are so unbelievably gigantic as to make the center of a star seem like an ice box, higher energies and far more massive particles can exist    A new and fascinating branch of physics, particle physics, has emerged within the last sixty years or so that seeks to examine the states of matter that exist at these high energies.  Also the adventure of particle physics takes us back to the beginning of our Universe close to THE BIG BANG when the familiar world of protons, neutrons and electrons were first evolving from a stupendously hot mixture of hitherto unknown and very massive and energetic particles.  These particles are produced even to-day by high energy cosmic events as evidenced by the existence of cosmic rays or in artificially in high energy particle accelerators. In a way these particle accelerators are ‘time machines’ taking us back to the first few seconds after the Big Bang when our Universe came into being. 

During the early years of the 1950s, experiments with cosmic rays revealed the presence of a number of highly energetic particles which rapidly decayed to our familiar protons, neutrons and electrons. Some of these particles carried electrical charges of +1 or -1 and others carried no charge at all.  Among them were particles referred to as muons, pions, kaons and lambda particles.   The new science of particle physics was emerging.    Particle physics is the study of the fundamental constituents of matter and the forces of nature. The discovery of some of these particles in cosmic ray investigations led to a series of experiments using very expensive and sophisticated apparatus which are called particle accelerators.  The basic principle of these apparatus is, that by accelerating some commonly known particles such as electrons, positrons, protons and anti-protons to extremely high speeds and then causing them to collide together, it is possible to produce and to detect a very large number of short lived particles.  Besides those particles found in cosmic rays a whole bewildering number of other high energy, very short lived particles were found.  They really only made sense when a number of physicists in particular Murray Gell Mann and George Zweig proposed the quark/gluon model for the proton and neutron.   Springing largely from the concept of quarks the so called Standard Model of the Nature of Matter was proposed

The Standard Model of the Nature of Matter

Matter is built up from particles called FERMIONS.  They are of two types, LEPTONS and QUARKS.  The Fermions are held together by fundamental forces, which are mediated by particles known as gauge bosons.  The BOSONS are PHOTONS, GLUONS and W+, W- and neutral Z bosons.

Leptons

LEPTONS are elementary particles which interact through the electromagnetic, weak, and gravitational forces, but do not interact through the strong (nuclear) force. Leptons are very small, less than 10−18 m in size. The ELECTRON is the best known and by far the most important lepton.  In fact together with the atomic nucleus it is the only one dealt with in ordinary chemistry and most branches of physics.  It is less than one thousandth the size of a nucleus and less than a hundred millionth the size of an atom. Indeed, existing measurements are consistent with leptons being point particles.  The electron and other leptons appear to be elementary and indivisible.

Six leptons are known. There are three known charged leptons: the electron (e), the muon (μ), and the tau (τ). Associated with each charged lepton is the family of leptons named NEUTRINOS by Enrico Fermi.  The name is derived from the Italian meaning very tiny neutral particles.   

The properties of the lepton family of particles are to be contrasted with the properties of the quark family of particles. Quarks interact through the strong force as well as through the electromagnetic, weak, and gravitational forces and are never found in the free form but only ‘imprisoned in hadrons’.

 Table of Leptons

Name

Symbol

Mass in MeV

Lifetime

Electric Charge

Electron

e-

0.511

stable

-1

Muon

µ-

105.6

2X10-6

-1

Tau

t-

1,777.0

3X10-13

-1

Electron-neutrino

ne

0.000003

stable

0

Muon-neutrino

nm

0.17

stable

0

Tau-neutrino

n t

18.00

stable

0

Particle Physicists use Electron volts (eVs) as their unit of energy. 1 eV is defined to be the energy required to move an electron through a potential difference of 1 Volt.  Since this is a very small unit they usually use Mega electron Volts 106eV (a million electron Volts) or as we head to higher energy physics 109 electron Volts Va Giga electron Volts or 109eV ( a billion electron volts ).

QUARKS

The properties of the lepton family of particles are to be contrasted with the properties of the quark family of particles. Quarks interact through the strong force as well as through the electromagnetic, weak, and gravitational forces and are never found in the free form but only ‘imprisoned in hadrons’..It is now thought with clear experimentally verified evidence that protons and neutrons are themselves composed of smaller particles called QUARKS.  They are ‘imprisoned’ within the proton or neutron by the STRONG FORCE.  They contain two types of quark, known as up quarks and down quarks.   The up quarks carry an electric charge of +2/3 and have an approximate mass of 4-5 Mega electron volts/c2 .  The down quarks carry an electric charge of -1/3 and a mass of approximately 8-10 Mega electron volts/c2

The simplest description of the proton is that it consists of two up quarks and one down quark bound by the strong force which is carried by the so called colour charges.   These are three in number and are called red, green and blue.   In the proton each individual quark carries a different colour charge.  The colour charge on the whole proton is said to be ‘white’.

However the proton within itself is not a fixed entity but is in a constant state of change.  Apart from quarks the proton contains particles called GLUONS. They have no mass and no electric charge.  However they carry the colour charges and constantly interact with the quarks.  The 'busy little gluons' constantly rush round and exchange colours charges with the quarks.  As shown in the very simplified diagram below a gluon carrying a blue charge exchanges its blue colour charge for the red charge on the  quark shown on the upper left in the first triplet in the diagram which then carries a blue charge and so for all the other quarks.  

In this way each individual quark is subjected to a constant ‘change of colour charge’.  This process is believed to be extremely rapid within the proton or neutron.

 

 

 

 


 

Remember that in the proton the two up quarks carry 2 X 2/3  positive charges and one down quark carries one – 1/3 negative charge.   The overall electric charge is +1 which is exactly equal and opposite to the – 1 charge on the electron. The proton belongs to a group of complex particles called HADRONS. It is the ONLY stable Hadron.  Speculation as to its possible decay gives it a life of more than 1032 years.

The neutron is unstable and on its own has a half life period of a little under15 minutes.  However in combination with one or more protons it can form stable atomic nuclei – see the web-page on isotopes.  The neutron consists of one up quark carrying an electrical charge of +2/3 and two down quarks each carrying an electrical charge of -1/3.  Thus overall the neutron carries no electrical charge.

With the exception of the neutron all other hadrons decay extremely rapidly to protons, neutrons and electrons – often through several intermediate stages.   

Although there are only two types of quarks in protons and neutrons and therefore in ordinary atoms, there are altogether six quarks which were present in the immensely hot and energetic early Universe immediately following the Big Bang.  They also occur in particle accelerator experiments   and (some of them) in cosmic rays.  These are listed in the table below.

The Table of Quarks

Name

Symbol

Mass in MeV

Lifetime

Electric Charge

Up

u

5

stable

+2/3

Down

d

10

Stable or variable

-1/3

Strange

s

100

short

-1/3

Charm

c

1,500

Very short

+2/3

Bottom

b

4,700

Extremely short

-1/3

Top

t

170,000

Extremely short

+2/3

 

HADRONS

Before the discovery of quarks and gluons the particle physics appeared very complicated in that a whole plethora of particles were discovered.   Besides the protons, anti-protons, neutrons and anti-neutrons there were a whole host of particles discovered in particles accelerator experiments.   They were of two types collectively referred to as HADRONS.  The most massive were called BARYONS and the less massive were called MESONS.  It is now known that Baryons (and anti-baryons) are all composed of quarks (or anti-quarks) cemented together by gluons.   The table below lists a few of the best known baryons.

Baryons

Name

Quarks

Mass in MeV

Half-life in seconds

Electric Charge

Proton

uud

938

Stable

+1

Neutron

udd

940

Stable in nuclei

Free half-life 15 minutes

0

Lambda

uds

1,115

2.6 X 10-10 seconds

0

Sigma-plus

uus

1,189

0.8 X 10-10

+1

Xi minus

dss

1,321

1.6 X 10-10

-1

Omega minus

sss

1,672

0.8 X 10-10

-1

Charmed Lambda

udc

2,280

2.2 X 10-13

+1

Anti–matter equivalents of all the baryons in the table above have also been detected.    The extraordinary half lives of all the baryons except for the proton and neutron should be noted.   It should be realized that 10-10 of a second is only one tenth of a billionth of a second.   The equipment needed to detect these extremely short lived particles is utterly amazing.

The second type of hadron is referred to as a MESON.  Just as with the short lived baryons a fairly large number of particles were discovered.  They are now known to consist of one quark and one anti-quark bound together by gluons

MESONS

Name

Composition

Mass in MeV

Lifetime in seconds

Charge

 Pion      p0

Up Anti-up

135

0.8 X 10-16

0

Pion      p0

Down Anti-down

135

0.8 X 10-16

0

 Pion      p+

Up Anti-down

140

2.6 X 10-8

+1

 Pion      p-

Down Anti-up

140

2.6 X 10-8

-1

     Kaon    K0

Down Anti-strange

498

10-10 or 10-8

0

     Kaon    K+

Up Anti-strange

494

1.2 X 10-8

+1

     Kaon    K-

Strange Anti-up

494

1.2 X 10-8

-1

Once again we notice that the lifetimes of these particles are extremely short

Anti–matter equivalents of all the baryons in the table above have also been detected.    The extraordinary short half lives of all the baryons except for the proton and neutron should be noted.   It should be realized that 10-10 of a second is only one tenth of a billionth of a second.   The equipment needed to detect these extremely short lived particles is utterly amazing.

The second type of hadron is referred to as a MESON.  Just as with the short lived hadrons a fairly large number of particles were discovered.  They are now known to consist of one quark and one anti-quark bound together by gluons

MESONS

Name

Composition

Mass

Lifetime in seconds

Charge

 Pion      p0

Up Anti-up

135

0.8 X 10-16

0

Pion      p0

Down Anti-down

135

0.8 X 10-16

0

 Pion      p+

Up Anti-down

140

2.6 X 10-8

+1

 Pion      p-

Down Anti-up

140

2.6 X 10-8

-1

     Kaon    K0

Down Anti-strange

498

10-10 or 10-8

0

     Kaon    K+

Up Anti-strange

494

1.2 X 10-8

+1

     Kaon    K-

Strange Anti-up

494

1.2 X 10-8

-1

Once again we notice that the lifetimes of these particles are extremely short

BOSONS

The particles which transmit the forces between the matter particles are called BOSONS.

There are 4 types of Bosons

PHOTONS – ‘particles’ of electromagnetic radiation.  They encompass a whole range of energies. 

Radio waves, Microwaves, Infra-red, visible light, ultra-violet, X-Rays and gamma rays.  

They mediate all the electromagnetic forces.  They have no mass but do carry energy.  They travel at 300,000 kilometers a second in a perfect vacuum.  They are slower when travelling through media.  Charged leptons such as electrons and positrons AND quarks are all subject to the electromagnetic force.

GLUONS – there are eight types of gluon.  They carry the colour forces between the quarks and unlike photons are confined within the proton, neutron or other hadron.  Like photons they have no mass.

W Particles - These short lived particles are involved in the Weak Reactions.  They occur in radioactive changes.  There are two such particles.  They are W+ and its anti-particle W-.     Unlike photons and gluons they have a high mass of 80.4 Giga electron volts.  This is very high – 80 Giga electron volts is 80,000 MeV – electrons are only 0.511 MeVs and even protons are ‘only’ 938.3 MeVs.

Z particles are like W+ and W- in that they are involved in the weak force.  The Z particle is neutral and has a mss of 91.19 Giga electron volts

Antimatter

The history of antimatter began in 1928 with a young physicist named Paul Dirac. He predicted the possible existence of a universe like ours made out of antimatter. From 1930, the search for antiparticles began.

Antimatter particles are the same as matter particles but carry the opposite electric charge.  They also have a number of other anti properties.  Thus the anti-electron has the same mass as the electron but carries a positive charge.  It is usually called a POSITRON.    All the other leptons, even the neutral neutrinos have the corresponding anti-matter particles. 

Anti-protons have the same mass as a proton but carry a negative charge.  This is because it is made up of anti-quarks.  The anti-up quark has an electric charge of -2/3 and the anti-down quark has an electric charge of +1/3.   This explains that although an anti-neutron still carries no overall electric charge this is because it consists of one anti-up with a charge of -2/3 and two anti-downs with charges of +1/3

Proton and Anti-proton compared with one another

          Up Quark                 Down Quark           Up Quark                                            Anti-up Quark         Anti-Down Quark     Anti-up Quark

             +2/3                         -1/3                         +2/3                                                            -2/3                        +1/3                  -2/3                             

                          Proton   Overall charge +1                                                Anti- Proton   Overall charge -1            

The Mass of BOTH proton and antiproton is 938.3 MeV/ c2 (1.6726 × 10−27 kg), or about 1836 times the mass of an electron or positron

Note that in both cases the mass of the proton or anti-proton is many times the masses of the constituent quarks or anti-quarks.

Besides having the opposite electric charge anti-particles also have a number of other anti-properties.  The magnetic moment of the antiproton has been found to be equal and opposite to that of the proton.   The anti-strange quark not only has the opposite electric charge to a strange quark but also has anti-strangeness.

However it must emphasised that both the neutron and the anti-neutron carry no overall electric charge.   The neutron is made up of three quarks and the anti-neutron of three anti-quarks.  In both cases the electric charges add up to an overall zero electric charge.

Neutron and Anti-neutron compared with one another

        Down Quark                  Up Quark           Down Quark                                         Anti-up Quark         Anti-Down Quark     Anti-up Quark

         -1/3                                  +2/3                      -1/3                                                           +1/3                       -2/3               +1/3                                            

                      Neutron   Overall charge Zero                                               Anti-neutron   Overall charge Zero          

Major steps forward in the search for the basic structure of matter have been achieved using particle accelerators and a whole range of both matter and antimatter particles have been produced.  Thus anti-electrons, (positrons), anti-protons and anti-neutrons can be made.  Even anti-hydrogen atoms have been made at Fermilab and at CERN.   One of the outstanding properties of anti-matter is that when an anti-matter particle meets the corresponding matter particle the two annihilate each other with the production of gamma radiation.  Thus matter is totally converted to energy.

In the late 1950s, the amount of antimatter in our galaxy was calculated to be less then one part in a hundred million. If there was an isolated system of antimatter in the Universe, free from interaction with ordinary matter, no earthbound observation could distinguish its true content because the photons are their own antiparticles and the spectra given out by anti-star would be the same as that given out by a star!  So, since there was no visible difference, the possibility of extragalactic antimatter was wide open.

At first, motivated by basic symmetry principles, it was believed that the Universe must consist of both matter and antimatter in equal amounts.   Thus it was thought that there might be anti-matter galaxies consisting of anti-stars, anti-planets and even anti-people.  If this was so there should be gamma radiation of the energies expected when anti-protons and positrons from the ‘frontier’ in the intergalactic space between a galaxy and an anti-galaxy met protons and electrons.  No such radiation has been detected.  I t might also have been just possible that anti-carbon and anti-oxygen nuclei may just have crossed the intergalactic ‘frontier’ and evaded collisions with matter particles and reached our area of space.  However, all attempts to detect such particles by space craft have always been negative. In 1998, for instance, a high-energy particle detector called the Alpha Magnetic Spectrometer (AMS) was flown on the Space Shuttle Discovery for a ten-day mission.   The presence of anti-carbon or anti-oxygen would have indicated the presence of anti-stars somewhere in the Universe since such nuclei could only be made in the blazing interiors of anti-stars in a triple anti-alpha reaction!

However, it is nowadays strongly believed that our Universe is composed primarily of matter and one of the most mysterious questions in particle physics is why the early Universe ended up with a very small excess of matter over anti-matter shortly after the Big Bang.

The amount of radiation compared to the amount of matter is about a billion to one and the current view is that for every billion particles of antimatter there were a billion and one particles of matter and that it is from this tiny residue that our Universe of matter is made.

One of the main experiments using the Large Hadron Collider will be aimed at solving the puzzle of what happened to the anti-matter.  It is thought that matter and antimatter were created in equal amounts in the Big Bang and that somehow the antimatter disappeared.  This meant that the Universe and everything in it, including ourselves, were made from the small amount of matter left over.

A press release was given on 11 April 2007 regarding the investigation of the ‘anti-matter problem’ by a team of UK scientists.

Scientists from the Universities of Liverpool and Glasgow have completed work on the inner heart of an experiment which seeks to find out what has happened to all the antimatter created at the start of the Universe.

The final modules of the VELO (VErtex Locator), a precision silicon detector, have been delivered to CERN, the European Particle Physics Laboratory in Geneva. Once assembled VELO will be installed into the LHCb detector, one of four experiments, which make up the Large Hadron Collider (LHC) particle accelerator, which is due to be switched in the near future. LHCb is designed to investigate the subtle differences between matter and antimatter in particles containing b (beauty) quarks. The LHC, located in a 27km underground tunnel which straddles France and Switzerland, will help answer some of the fundamental questions about the origins of our Universe and is set to change the future path of particle physics research.

Within the LHC, two beams of protons will be accelerated close to the speed of light and then collided in one of the four experiments, which will each measure the outfall of particles.

Professor Themis Bowcock, lead scientist from the University of Liverpool LHCb team said, “The VELO allows us to isolate samples of b quarks for analysis.” 

Dr Tara Shears, LHCb scientist from the University of Liverpool explains, “When operational 40 million proton proton interactions will occur per second inside LHCb and it is no mean feat that measurements of these collisions will take place in real time.

(B quarks are also known as Bottom Quarks).

 

Particle Accelerators

Some of the information on the composition of the Universe is derived from astronomical sources such as the study of cosmic rays and gamma ray bursts.   However most of our understanding is derived from experiments using particle accelerators.

Just after the Big Bang, the Universe was a rapidly expanding ball of incredibly hot fundamental particles.  As the Universe expanded it cooled and the particles decayed and changed into other lower energy fundamental particles.  Finally the ordinary familiar matter we find to-day was formed namely protons, neutrons, electrons and neutrinos as well as gluons and photons.

In particle accelerators beams of fundamental particles are smashed together in head on collisions that are so energetic that they turn the clock back to fractions of a second after the Big Bang.  Thus the extremely high energy produces the fundamental particles that were present in the early universe.  By studying the behaviour of the particles scientists are trying to find out why the Universe is made the way it is.

The more energetic the collisions, the more likely we are to ‘resurrect’ fundamental particles.  For example the bottom and the top quark and the tau were discovered at the Fermilab.   One of the objects of the even more ambitious Large Hadron Collider is to try to reach high enough energies to form the Higgs Boson which many particle physicists believe to be the particle which gave the other particles such as the quarks and leptons the property we call MASS.  Once the fundamental particles have been produced their behaviour can be studied to try to find out why the Universe is constructed in the way that it is.

CERN

CERN is the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva.

It is the home of The Large Hadron Collider which is the largest Particle Accelerator in the world.

Geneva, 22 June 2007. Speaking at the 142nd session of the CERN1 Council today, the Organization’s Director General Robert Aymar announced that the Large Hadron Collider (LHC) will start up in May 2008, taking the first steps towards studying physics at a new high-energy frontier. A low-energy run originally scheduled for this year has been dropped as the result of a number of minor delays accumulated over the final months of LHC installation and commissioning, coupled with the failure in March of a pressure test in one of the machine’s components.

The LHC is a scientific instrument of unprecedented complexity, and at 27 kilometres in circumference, the world’s largest superconducting installation. Cooling the first sector of the machine to a temperature of 1.9 K (-271.3°C), colder than outer space, began earlier this year and has provided an important learning process. The first sector cool down has taken longer than scheduled, but has allowed the LHC’s operations team to iron out teething troubles and gain experience that will be applied to the machine’s seven remaining sectors. Now cold, tests on powering up the sector have begun and the cool down of a second sector will soon be underway.

Cooling is carried out using liquid helium

‘The Coolest Place in the Universe’ CERN

Illustration CERN 2007 Copywrite DSU - Communication Group

 

Scientists in the tunnel near the machine which will soon be used to study the highest energies yet produced on Earth.

Illustration Credit CERN Website

Particles are extremely tiny, and to be able to see and study them, scientists need very special tools.

They need accelerators, huge machines able to speed up particles to very high energies before smashing them into other particles.

Around the points where the "smashing" occurs, scientists build detectors to carry out experiments which allow them to observe and study the collisions. These are instruments, sometimes huge, made of several kinds of particle detectors.

By accelerating and smashing particles, physicists can identify their components or create new particles, revealing the nature of the interactions between them.

The Member States of CERN are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom.   India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

The Fermi Lab and the Tevatron

Fermi National Accelerator Laboratory advances the understanding of the fundamental nature of matter and energy by providing leadership and resources for qualified researchers to conduct basic research at the frontiers of high energy physics and related disciplines.  Until the Large Hadron Collider swings into operation in 2008 it will remain the largest accelerator in the world.

The Fermi National Accelerator Laboratory advances the understanding of the fundamental nature of matter and energy by providing leadership and resources for qualified researchers to conduct basic research at the frontiers of high energy physics and related disciplines.  Until the Large Hadron Collider swings into operation in 2008 it will remain the largest accelerator in the world.  Fermilab was originally named the National Accelerator Laboratory, was commissioned by the U.S. Atomic Energy Commission, under a bill signed by President Lyndon B. Johnson on November 21, 1967.On May 11, 1974, the laboratory was renamed in honor of 1938 Nobel Prize winner Enrico Fermi, one of the preeminent physicists of the atomic age. Fermi's widow, Laura Fermi, spoke at the dedication ceremonies.

Two major components of the Standard Model of Fundamental Particles and Forces were discovered at Fermilab: the bottom quark (May-June 1977) and the top quark (February 1995). In July 2000, Fermilab experimenters announced the first direct observation of the tau neutrino. One of the greatest triumphs of the tevatron at Fermilab were the discoveries of the TOP QUARK and the TAU NEUTRINO.  These discoveries completed the set of particles required by the Standard Model.  The Top Quark was detected after colliding protons and anti-protons with one another and enormously high velocities (giving huge energies on collision).

The Tevatron is to date the largest circular accelerator.  It is soon destined to be replaced as TOP DOG (Pun intended!) by the Large Hadron Collider at CERN.

Illustration Courtesy Fermilab Tevatron

A TeV is a unit of energy used in particle physics. 1 TeV is about the energy of motion of a flying mosquito. What makes the LHC so extraordinary is that it squeezes energy into a space about a million million times smaller than a mosquito.

Deutsches Elekronen Synchroton DESY

Another function of the particle accelerators is to probe the inner structure of the quarks.  One of the most productive results has been obtained at the research laboratories at DESY (Deutsches Elektronen-Synchrotron) near Hamburg, Germany

The HERA Experiments at DESY

In the large circular accelerator, electrons and protons collide in HERA (Hadron Electron Ring Accelerator).  In HERA, electrons were accelerated in a ring in one direction, the protons in another ring, in the opposite direction.  The two accelerator rings occupied the same tunnel which forms a circle 6.3km in circumference.  The rings intersected at four points around the tunnel, where the electrons and protons collided head on and where the results were detected and later studied.  Illustrations Courtesy DESY HERA

 

 

 The above image represents of the inner structure of a proton as "seen" at HERA.  The purple particles are quarks, the green particles are anti-quarks, and the black spirals are gluons.  There are three more quarks than anti-quarks.  These are the three quarks we would normally refer to when speaking of the proton (two up, one down).  The other pairs of quarks and anti-quarks exist only momentarily; formed from an energetic gluon, they will come back together and annihilate returning once again to a gluon.  As we probe to the smallest current "visibility" we can see up to 100 of these quark/anti-quark pairs at any instant.  It turns the simple picture we have of the proton as a kind of static collection of 3 quarks and 8 gluons  into object with quark-anti-quark pairs, gluons of 8 varieties, three colour forces and two positively charged (+2/3) quarks and one negatively charged (-1/3) quark all in a state of constant change.

The Facility at HERA was sadly closed in Spring 2007 after a very fruitful period of research.  DESY however is still carrying on its work particle physics and is deeply involved in the plans for new International Linear Collider ( see below)

The inference to be drawn from these discoveries at HERA is that the protons are constant states of change and that every individual proton although similar to all other protons is unique – every proton in the universe is not only different to every other proton in the Universe but has a different history in the past and will have a different future.

Here we have an example of where the particle physics is taking us.    It seems as if we are entering a world where some of the Buddhist and Taoist sayings would not be out of place.    Even the proton itself is constantly changing where ghostly particles seem to float into and then out of existence as the massless gluons transform into mass particles (quarks and anti-quarks) which fade back into gluons.   Bosons are transforming into quark and anti-quark pairs and back again.

The discoveries being made at the great particle accelerators combined with mind stunning observations of modern astronomy show a picture of a Universe of supremely elegant beauty.  Among them are the results of those experiments that are now probing the nature of the proton.  We now know that even the discovery that it is a complex particle made of quarks and gluons is a vast oversimplification of its true nature.  The experiments at HERA have lifted ever so slightly the veil that conceals wonders beyond belief  -  each single proton is a world of its own which like the clouds of water vapour in the sky are constantly changing as virtual quarks and anti-quarks flit in and out of existence.  Highly energetic gluons seem to form ‘meson-like ghosts’ within the proton which fade back again into gluons.   Even the ‘permanent’ up and down quarks are constantly being subjected to inconceivably rapid changes in the colour charges which hold the quarks within the tiny world of the proton.  Each proton is a world in itself - at every single pico-second we shall find that each proton has changed its internal structure.   All protons are in a constant state of change.  This means that just as every person and every blade of grass are different, every proton in the Universe may turn out to be a unique tiny world on its own containing different past histories and destined to have different futures to every other proton.   Each proton is changing at an inconceivably fast rate that staggers the imagination.   In yet in the midst of all this diversity the Universe is one.

It is a picture that confronts us with an inspiring and elegant picture of the beauty of the wonderful Universe of which we are all a part   It reminds us of the magnificent yet mysterious statements of Mahayana Buddhism such as those found in the Heart Sutra – form is not other than emptiness and emptiness not other than form.   Form is precisely emptiness and emptiness precisely form.   

Also, we are confronted with the koans of Zen – What is the sound of one hand clapping – Samsara is Nirvana.  

 Or the words of the Tao Te Ching.  The Tao gives birth to one.  One gives birth to two.  Two gives birth to three.  Three gives birth to all things

Questions of importance

Was there a time close to the Big Bang when the huge temperatures overcame the strong force and the quarks were not imprisoned within hadrons?   Just as in stars atoms do not exist instead there is a plasma of electrons and nuclei could there have been a quark-gluon plasma.

Why is there very little anti-matter?  Why do we live in an asymmetric Universe of Matter?

Why do leptons, quarks and W and Z bosons have mass?  What is the Origin of Mass?  It is postulated that there was a boson called after its originator the Higgs boson that gave the particles mass.  One of the aims of the Large Hadron Collider is to produce and detect Higgs Bosons.

Both photons and gluons appear to have no mass – why?

Are there other dimensions and can we detect one or more of them in the LHC?   String Theory and its elaboration in the M Theory suggests that there are 11 dimensions in all. 

There is a current theory that our Universe may be only one of a huge number of universes in a MULTVERSE.   The laws of nature may be different in each universe.

International Linear Collider

For more than twenty years now, the Tevatron at Fermilab, the world's most powerful particle accelerator, has opened a doorway to exploring the deepest mysteries of the universe. In 2008, an even more powerful accelerator, the Large Hadron Collider will begin operation at CERN in Geneva, Switzerland. An international consortium of particle physicists has made a proposal for the next step: the International Linear Collider.   This machine will be truly international bringing scientists from Asia, America and Europe together  in a truly world wide effort. Particle physicists around the world have reached the conclusion that a linear collider, which brings electrons and positrons into collisions at energies up to 1 TeV should be the next big particle physics facility in the world.

Unlike some of the most powerful accelerator the International Linear Collider will not be a circular collider like the Tevatron, HERA or the Large Hadron Collider at CERN it will be a linear collider.   Stretching approximately 35-kilometers in length, this electron-positron collider will allow researchers to discover the Terascale, an energy region that may answer some of the most fundamental questions of all time.

Scientists now believe that only 4-5% of the Universe consists of the type of matter we have so far studied - the remaining 95 percent consists of mysterious dark matter and dark energy, revealing a universe far stranger and more wonderful than they ever suspected. The global particle physics community agrees that a precision machine—the proposed International Linear Collider—will answer these questions about what the universe is made of and provide exciting new insights into how it works. Using unprecedented technology, discoveries are within reach that could stretch our imagination with new forms of matter, new forces of nature, new dimensions of space and time.

 

The International Linear Collider will give physicists a new cosmic doorway to explore energy regimes beyond the reach of today’s accelerators. A proposed electron-positron collider, the ILC will complement the Large Hadron Collider at the European Center for Nuclear Research (CERN) in Geneva, Switzerland, together unlocking some of the deepest mysteries in the universe. With LHC discoveries pointing the way, the ILC—a true precision machine—will provide the missing pieces of the puzzle.

Consisting of two linear accelerators that face each other, the ILC will hurl some 10 billion electrons and their anti-particles, positrons, toward each other at nearly the speed of light. Superconducting accelerator cavities operating at temperatures near absolute zero will give the particles more and more energy until they smash in a blazing crossfire at the centre of the machine. Stretching approximately 35 kilometres in length, the beams will collide 14,000 times every second at extremely high energies—500 billion-electron-volts (GeV). Each spectacular collision will create an array of new particles that could answer some of the most fundamental questions of all time. The current baseline design allows for an upgrade to a 50-kilometre, 1 trillion-electron-volt (TeV) machine during the second stage of the project.

The geolographical position of this amazing machine has not yet been decided.  The Tevatron is in North America, the Large Hadron Collider in Europe.  The Asian scientists are pressing for a position in Asia.  Each continent is represented by a top scientific leader under one central co-ordinator.   On Friday, March 18, the appointment of Professor Barry Barish was announced as Director of the Global Design Effort for the proposed International Linear Collider. Barish is Linde Professor of Physics at the California Institute of Technology and is currently director of the LIGO laboratory. (The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a facility dedicated to the detection of cosmic gravitational waves and the harnessing of these waves for scientific research.)

Dark Matter and Dark Energy

In the last few years scientists have discovered an amazing fact.  Just when we thought we had reached a a point when we had a fairly good picture of the Universe a new and weird discovery was made.  The world we know – the world of electrons, quarks, photons and gluons constitutes only 4-5 % of what exists.   First it was discovered that a huge amount of matter existed which did not react with ordinary matter.   In fact this mysterious ‘substance’ was subject to gravity but in all other ways appeared to be undetectable.  This material represented far more matter than our normal matter.  Astronomers have detected the gravitational effects of large amounts of matter that can’t be seen. It is called ‘Dark Matter’. One possible explanation of dark matter is that it consists of particles named supersymmetric particles.  It is hoped that the Large Hadron Collider may find these so far undetected particles and that this will help to explain one mystery of the Universe – missing or ‘dark’ matter.

Over the past five years, the mysterious tale of dark matter has been taken yet another bizarre twist. Just as cosmologists decided that the Universe is full of a strange invisible matter, they then realised that space was even weirder than they had thought. 
The new component seems even stranger than dark matter. Not only is it invisible just like dark matter, but it must have a repulsive force, otherwise it would get sucked into galaxies and affect their motion. So this mysterious stuff has been labelled 'dark energy' and is a kind of cosmic antigravity force that counteracts the attractive force of gravity. This means that instead of the expansion of the Universe slowing down, in fact, it is speeding up. Recent measurements of distant supernovae agreed with this conclusion, finding that the Universe was indeed expanding with increasing pace.

Recent experiments and observations have shown that 95% of the Universe's energy density seemingly lies in a Dark Sector comprising Dark Matter, a form of yet undiscovered matter, and Dark Energy, whose origin is unknown.

 

Deep and Profound Questions

Was there a time close to the Big Bang when the huge temperatures overcame the strong force and the quarks were not imprisoned within hadrons?   Just as in stars atoms do not exist instead there is a plasma of electrons and nuclei could there have been a quark-gluon plasma.

Why is there very little anti-matter?  Why do we live in an asymmetric Universe of Matter?

Why do leptons, quarks and W and Z bosons have mass?  What is the Origin of Mass?  It is postulated that there was a boson called after its originator the Higgs boson that gave the particles mass.  One of the aims of the Large Hadron Collider is to produce and detect Higgs Bosons.

Both photons and gluons appear to have no mass – why?

Are there other dimensions and can we detect one or more of them in the LHC?   String Theory and its elaboration in the M Theory suggests that there are 11 dimensions in all. 

STRING THEORIES

The theory that at a level many orders of magnitude smaller than the fundamental particles (leptons and quarks), matter was made up of tiny vibrating strings about 10-36 meters long was first postulated in the 1970s.  This is not to say that particles such as electrons and quarks do not exist anymore than the next order of matter atoms do not exist but that at a deeper level matter is made up of tiny strings.    The particles are really a manifestation of these tiny vibrating strings and that it is the mode of the vibration of the strings that determine the nature of the fundamental particle formed.   Certain weird results appear to be connected with string theories – the strangest of all is that the strings vibrate in at least 10 dimensions.  In the lofty realms of higher mathematics the ‘string mathematicians’ evolved not one ‘strain theory’ but 4 theories.  These pointed to one unifying theory which is called ‘M’ Theory and requires eleven dimensions.

A further elaboration of  string theory suggests not only the ‘ordinary tiny strings but another type called cosmic superstrings which involve one-dimensional strings billions of light years long of fantastically high density (about a million metric megatons per centimeter.  (A full discussion of the Cosmic String Theory is given in the October 2005 edition of the American ‘Astronomy’ magazine which comes out every month and is available at newsagents.)

The Multiverse

Making Multiverses article by Steve Nadia in Astronomy Magazine October 2005 special edition on cosmology.  Quote from Max Tegmark  "I fully expect the true nature of reality to be weird and counterintuitive, which is why I believe these crazy things."

There are now a growing number of theories among cosmologists that our universe is only one of many.  They are supported by the possibility of other dimensions as hinted at in 'M' Theory and other string theories and by the weakness of the gravitational force when compared to the other three forces - the electromagnetic, the weak force and the strong nuclear colour forces

The idea of parallel universes was admirably suggested by that great science fiction writer of the late nineteenth and early twentieth century H.G.Wells in his story entitled 'Men like Gods' he describes a utopian planet in a parallel universe.  In the first half of the twentieth century science fiction stories were often referred to as 'Wellsian fantasies'. Although the main theme of the book is to critisise the bad way we run things on Earth compared to the wonderful idyllic world of Utopia the book is remarkably prophetic in its treatment of the MULTIVERSE as we now call it.  The opening chapters of the book concern the adventures of Mr Barnstable and a number of other 'earthlings' who are riding along a road near Windsor and suddenly find themselves driving along another road in what turns out to be a parallel universe. The Earthlings are taken to a conference chamber in which they listen (by some form of telepathy) to a discourse by a man from Utopia called Serpentine.   Serpentine began "For most practical purposes the particular universe in which we find ourselves could be regarded as occurring in a space of three spatial dimensions moving through a dimension of time..  It was only by great efforts of sustained analysis that we were able to realise that this universe in which we lived not only extended  but was slightly bent and contorted into a number of other long unsuspected spatial dimensions.  It extended beyond its three chief spatial dimensions into these others just as a thin sheet of paper, not only by virtue of its thickness, but also by its crinkles and curvatures extends into a third dimension."  Serpentine proceeded "- just as it would be possible for any number of practically two dimensional universes to lie side by side like sheets of paper in a three dimensional space, so in a many dimensional space about which we are now beginning to acquire knowledge it is possible for innumerable three-dimensional universes to lie side by side (in a higher spatial dimension) and to undergo a roughly parallel movement through time.  The theoretical work of the mathematical cosmologists Lonestone and Cephalus had long since given us the soundest basis for the belief that there are a very great number of space and time universes, parallel to one another, resembling each other, nearly but not exactly, much as the leaves of a book might resemble one another.  The daring experiments of the man and woman who brought you into this world named Arden and Greenlake used the -------thrust of the atom to rotate a portion of the Utopian material universe in the F dimension in which it had long been known to extend and much as a gate is swung on its hinges brought you people from another world into ours .  Although our brother and sister were killed by a sudden release of force the door that they opened need never be close again..  We shall be able to go out from Utopia into a whole folio of hitherto unimagined worlds.."  Serpentine went on," this sister universe to ours is so far as we can judge a little retarded in time in relation to our own..  We can not suppose that they are exactly parallel to us since no two particles of matter are (exactly) alike.  In all the dimensions of being there has never been and never can be an exact repetition.  (See my remarks above about the uniqueness of every proton from every other proton. All protons are in a constant state of change.  This means that just as every person and every blade of grass are different, every proton in the Universe may turn out to be a unique tiny world on its own containing different past histories and destined to have different futures to every other proton.)

I feel you will agree that this was not a bad guess for a man who had never heard of quarks or gluons and moreover had never heard of  string theories with ten or eleven dimensions.  The book was published in 1923.   Incidentally, Wells also predicted universal television all over the world which he called the kinetotelephotograph.  This was in his book 'When the Sleeper Awakes' published in 1898.  In the same book he predicted aerial warfare and a sort of unbreakable glass.   In another book first published in 1914 he predicted the building of atomic power stations and a terrible war in which atomic bombs using a new synthetically produced chemical element called carolinium.  Although the mechanism by which carolinium was said to release awesome amounts of destructive energy was different, in many ways it can be said to resemble  plutonium in its destructive power.  Bearing in mind the time it was written, 1914, it was an amazingly prophetic book.  It also included reference to the synthetic production of gold.  True we do not regularly produce gold but we do synthesize a number of elements industrially such as technecium, americium and several isotopes of plutonium.

To-day there are many cosmologists who look to the possibility of extra-dimensions of space and of other universes  Some of them my be very like our universe as predicted by H.G.Wells in his book.  Other however may be utterly different.  In several of his books the Astronomer Royal Professor Lord Martin Rees puts forward the possibility that the actual laws of nature may vary in different universes.   In his book Just Six Numbers he points out that he reason our Universe is just right for life is that the forces are just right - a kind of 'Goldilocks Universe'  where everything 'is just right'.   He points out if the forces were different we would end up with quite different universes.  If gravity were too weak there would be no stars or planets - if it was too strong then the Big Bang would have gone back into a rapid Big Crunch.

Perhaps the masses of fundamental particles such as quarks and electrons may be different.  If the masses of the up and down quarks were reversed what would this mean. If the neutron were completely stable and the proton had a half-life of 15 minutes instead of the other way round what would this do for 'chemistry'.

Perhaps there are anti-universes where anti-matter won the great matter/anti-matter war at the dawn of time.  The possibilities are endless

Many thanks are due to Tara Shears from the University of Liverpool for answering some of my difficult questions and for her illuminating lecture on 21 June at the Royal Society on the Large Hadron Collider.

 

Hyperlinks

Isotopes New Page 2

STARS

Home