Contribution in Science.
Cosmology
(Courtesy of Wikipedia, Encyclopedia)
Cosmology (from the Greek κόσμος, kosmos "world" and -λογία, -logia "study of") is a branch of astronomy concerned with the studies of the origin and evolution of the universe, from the Big Bang to today and on into the future. It is the scientific study of the origin, evolution, and eventual fate of the universe. Physical cosmology is the scientific study of the universe's origin, its large-scale structures and dynamics, and its ultimate fate, as well as the laws of science that govern these areas.[2]
The Hubble extreme Deep Field (XDF) was completed in September 2012 and shows the farthest galaxies ever photographed. every speck of light in the photo is an individual galaxy, some of them
as old as 13.2 billion years; the observable universe is estimated to
contain more than 2 trillion galaxies.[1]
Religious or mythological cosmology is a body of beliefs based on mythological, religious, and esoteric literature and traditions of creation myths and eschatology.
Physical cosmology is studied by scientists, such as astronomers and physicists, as well as philosophers, such as metaphysicians, philosophers of physics, and philosophers of space and time.
Cosmology differs from astronomy in that the former is concerned with
the Universe as a whole while the latter deals with individual celestial objects. Modern physical cosmology is dominated by the Big Bang theory, which attempts to bring together observational astronomy and particle physics;[5][6] more specifically, a standard parameterization of the Big Bang with dark matter and dark energy, known as the Lambda-CDM model.
The Cosmic Microwave Background (CMB) is the cooled remnant of the first light that could ever travel freely throughout the Universe.
Scientists consider it as an echo or 'shockwave' of the Big Bang. Over time, this primeval light has cooled and weakened considerably; nowadays we detect it in the microwave domain.
The CMB radiation was discovered by chance in 1965. Penzias and Wilson, two radio astronomers in the United States, registered a signal in their radio telescope that could not be attributed to any precise source in the sky.
Cooler, clearer Universe
It took about 300 000 years for the Universe to cool down to a temperature at which atoms can form (about 3000°C). Matter then became neutral, and allowed the light to travel freely: the Universe became transparent. The relic of that 'first light' is the CMB.
Since the time when that radiation was released, the Universe has expanded, becoming at the same time cooler and cooler. The cosmic background has been affected by the same process: it has expanded and cooled down. Space has 'stretched' itself, and with it all length scales.
https://www.esa.int/Science_Exploration/Space_Science/Herschel/Cosmic_Microwave_Background_CMB_radiation
Big Bang
The Big Bang theory is the prevailing cosmological model for the universe[1] from the earliest known periodsthrough its subsequent large-scale evolution.[2][3][4] The model describes how the universe expanded from a very high-density and high-temperature state,[5][6] and offers a comprehensive explanation for a broad range of phenomena, including the abundance of light elements, the cosmic microwave background (CMB), large scale structure and Hubble's law.[7]
Detailed measurements of the expansion rate of the universe place the
Big Bang at around 13.8 billion years ago, which is thus considered the age of the universe.[8] After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms. Giant clouds of these primordial elements later coalesced through gravity in halos of dark matter, eventually forming the stars and galaxies visible today.
Since Georges Lemaître first
noted in 1927 that an expanding universe could be traced back in time
to an originating single point, scientists have built on his idea of
cosmic expansion. The scientific community was once divided between
supporters of two different theories, the Big Bang and the Steady State theory, but a wide range of empirical evidence has strongly favored the Big Bang which is now universally accepted.[9] In 1929, from analysis of galactic redshifts, Edwin Hubble concluded
that galaxies are drifting apart; this is important observational
evidence consistent with the hypothesis of an expanding universe. In
1964, the cosmic microwave background radiation was discovered, which was crucial evidence in favor of the Big Bang model,
Special Theory of Relativity
In physics, special relativity (also known as the special theory of relativity) is the generally accepted and experimentally confirmed physical theory regarding the relationship between space and time. In Albert Einstein's original pedagogical treatment, it is based on two postulates:
1. the laws of physics are invariant (i.e. identical) in all inertial frames of reference (i.e. non-accelerating frames of reference); and
2. the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source or observer.
Some of the work of Albert Einstein in special relativity is built on the earlier work by Hendrik Lorentz.
Special relativity was originally proposed by Albert Einstein in a paper published on 26 September 1905 titled "On the Electrodynamics of Moving Bodies".[p 1] The inconsistency of Newtonian mechanics with Maxwell's equations of electromagnetism and,
experimentally, the Michelson-Morley null result (and subsequent
similar experiments) demonstrated that the historically hypothesized luminiferous aether did
not exist. This led to Einstein's development of special relativity,
which corrects mechanics to handle situations involving all motions and
especially those at a speed close to that of light (known as relativistic velocities).
Today, special relativity is proven to be the most accurate model of
motion at any speed when gravitational effects are negligible. Even so,
the Newtonian model is still valid as a simple and accurate
approximation at low velocities (relative to the speed of light), for
example, the everyday motions on Earth.
Special relativity has a wide range of consequences. These have been experimentally verified,[1] and include length contraction, time dilation, relativistic mass, mass–energy equivalence, a universal speed limit, the speed of causality and relativity of simultaneity.
It has, for example, replaced the conventional notion of an absolute
universal time with the notion of a time that is dependent on reference
frame and spatial position. Rather than an invariant time interval between two events, there is an invariant spacetime interval. Combined with other laws of physics, the two postulates of special relativity predict the equivalence of mass and energy, as expressed in the mass–energy equivalence formula E = mc2 (c is the speed of light in a vacuum).[2][3]
A defining feature of special relativity is the replacement of the Galilean transformations of Newtonian mechanics with the Lorentz transformations.
Time and space cannot be defined separately from each other (as was
earlier thought to be the case). Rather, space and time are interwoven
into a single continuum known as "spacetime". Events that occur at the same time for one observer can occur at different times for another.
Until Einstein developed general relativity,
introducing a curved spacetime to incorporate gravity, the phrase
"special relativity" was not used. A translation sometimes used is
"restricted relativity"; "special" really means "special case".[p 2][p 3][p 4][note 1]
The theory is "special" in that it only applies in the special case where the space time is "flat", i.e., the curvature of spacetime, described by the energy-momentum tensor and causing gravity, is negligible.[4][note 2] In
order to correctly accommodate gravity, Einstein formulated general
relativity in 1915. Special relativity, contrary to some historical
descriptions, does accommodate accelerations as well as accelerating frames of reference.[5][6]
Higgs boson
Courtesy of Wikipedia, the Encyclopedia
Physicists explain the properties of forces between elementary particles in terms of the Standard Model – a widely accepted framework for understanding almost everything in physics in the known universe, other than gravity. (A separate theory, general relativity, is used for gravity.) In this model, the fundamental forces in nature arise from properties of our universe called gauge invariance and symmetries. The forces are transmitted by particles known as gauge bosons.[13][14]
In the Standard Model, the Higgs particle is a boson with spin zero, no electric charge and no colour charge. It is also very unstable, decaying into other particles almost immediately.
The Higgs field has a "Mexican hat-shaped" potential. In its ground state,
this causes the field to have a nonzero value everywhere and as a result, below a very high ek isospin symmetry of the electroweak interaction. 15
History
Particle physicists study matter made from fundamental particles whose interactions are mediated by exchange particles – gauge bosons – acting as force carriers.
At the beginning of the 1960s a number of these particles had been proposed, along with theories suggesting how they relate
to each other, some of which had already been reformulated as field theories in which the objects of study are not particles and forces, but quantum fields and their symmetries.[51]:
Paand mathematician Peter Woit summarised the state of research at the time.
The Higgs mechanism is a process by which vector bosons can acquire rest mass without explicitly breaking gauge invariance, as a byproduct of spontaneous symmetry breaking.[55][56] Initially, the mathematical theory behind spontaneous symmetry breaking was conceived and published within particle physics by Yoichiro Nambu in 1960,[57] and
the concept that such a mechanism could offer a possible solution for
the "mass problem" was originally suggested in 1962 by Philip Anderson
(who had previously written papers on broken symmetry and its outcomes
in superconductivity.[58] Anderson
concluded in his 1963 paper on the Yang-Mills theory, that "considering
the superconducting analog... [t]hese two types of bosons seem capable
of canceling each other out... leaving finite mass bosons"),[59][60] and in March 1964, Abraham Klein and Benjamin Lee showed
that Goldstone's theorem could be avoided this way in at least some
non-relativistic cases, and speculated it might be possible in truly
relativistic cases.[61]
Properties of the model were further considered by Guralnik in 1965,[67] by Higgs in 1966,[68] by Kibble in 1967,[69] and further by GHK in 1967.[70] The original three 1964 papers demonstrated that when a gauge theory is
combined with an additional field that spontaneously breaks the
symmetry, the gauge bosons may consistently acquire a finite mass.[55][56][71] In 1967, Steven Weinberg [72] and Abdus Salam[73]independently showed how a Higgs mechanism could be used to break the electroweak symmetry of Sheldon Glashow's unified model for the weak and electromagnetic interactions,[74] The resulting electroweak theory and Standard Model have accurately predicted (among other things) weak neutral currents, three bosons, the top and charm quarks, and with great precision, the mass and other properties of some of these.[d] Many of those involved eventually won Nobel Prizes or other renowned awards. A 1974 paper and comprehensive review in Reviews of Modern Physics commented
that "while no one doubted the [mathematical] correctness of these
arguments, no one quite believed that nature was diabolically clever
enough to take advantage of them",[80] adding
that the theory had so far produced accurate answers that accorded with
experiment, but it was unknown whether the theory was fundamentally
correct.[81] By
1986 and again in the 1990s it became possible to write that
understanding
Higgs
Field: An Energy House of Universe
According to the Standard Model, a field of the necessary kind (the Higgs field) exists throughout space and breaks certain symmetry laws of the electroweak interaction.[e] Via
the Higgs mechanism, this field causes the gauge bosons of the weak
force to be massive at all temperatures below an extreme high value.
When the weak force bosons acquire mass, this affects their range, which
becomes very small.[f] Furthermore,
it was later realised that the same field would also explain, in a
different way, why other fundamental constituents of matter (including electrons and quarks) have mass.
The Higgs field is scalar and has a non-zero constant value in vacuum.
The existence of the Higgs field became the last unverified part of the
Standard Model of particle physics, and for several decades was
considered "the central problem in particle physics".[18][19]
The presence of the field, now confirmed by experimental investigation, explains why some fundamental particles have mass, despite the symmetries controlling
their interactions implying that they should be massless. It also
resolves several other long-standing puzzles, such as the reason for the
extremely short range of the weak force.
The importance of this fundamental question led to a 40-year search, and the construction of one of the world's most expensive and complex experimental facilities to date, CERN's Large Hadron Collider,[20] in
an attempt to create Higgs bosons and other particles for observation
and study. On 4 July 2012, the discovery of a new particle with a mass
between 125 and 127 GeV/c2 was announced; physicists suspected that it was the Higgs boson.[21][22][23]
Higgs boson
The hypothesised Higgs mechanism made several accurate predictions,[d][26]:22 however to confirm its existence there was an extensive search for a matching particle associated with it – the "Higgs boson".[8][9] Detecting
Higgs bosons was difficult due to the energy required to produce them
and their very rare production even if the energy is sufficient. It was
therefore several decades before the first evidence of the Higgs boson
was found. Particle colliders, detectors, and computers capable of looking for Higgs bosons took more than 30 years (c. 1980–2010) to develop.
By
March 2013, the existence of the Higgs boson was confirmed, and
therefore, the concept of some type of Higgs field throughout space is
strongly supported.[21][23][6] The nature and properties of this field are now being investigated further, using more data collected at the LHC.[1]
Particle physics
The Higgs boson validates the Standard Model through the mechanism of mass generation.
As more precise measurements of its properties are made, more advanced
extensions may be suggested or excluded. As experimental means to
measure the field's behaviours and interactions are developed, this
fundamental field may be better understood. If the Higgs field had not
been discovered, the Standard Model would have needed to be modified or
superseded.
The Higgs discovery, as well as the many measured collisions occurring
at the LHC, provide physicists a sensitive tool to parse data for where
the Standard Model fails, and could provide considerable evidence
guiding researchers into future theoretical developments
Discovery of candidate boson at CERN
On 4 July 2012 both of the CERN experiments announced they had independently made the same discovery:[114] CMS of a previously unknown boson with mass 125.3 ± 0.6 GeV/c2[115][116] and ATLAS of a boson with mass 126.0 ± 0.6 GeV/c2.[117][118]
On
31 July 2012, the ATLAS collaboration presented additional data
analysis on the "observation of a new particle", including data from a
third channel, which improved the significance to 5.9 sigma (1 in 588
million chance of obtaining at least as strong evidence by random
background effects alone) and mass 126.0 ± 0.4 (stat) ± 0.4 (sys) GeV/c2,[118] and CMS improved the significance to 5-sigma and mass 125.3 ± 0.4 (stat) ± 0.5 (sys) GeV/c2.[115
Confirmation of existence and current status
On 14 March 2013 CERN confirmed that:
"CMS
and ATLAS have compared a number of options for the spin-parity of this
particle, and these all prefer no spin and even parity [two fundamental
criteria of a Higgs boson consistent with the Standard Model]. This,
coupled with the measured interactions of the new particle with other
particles, strongly indicates that it is a Higgs boson."[6]
CERN
(Courtesy of Wikipedia, Encyclopedia).
European Organization for Nuclear Research Organisation européenne pour la recherche nucléaire | |
Member states | |
Formation | |
Headquarters | |
Membership | |
Official languages | |
Council President | |
Website | |
The European Organization for Nuclear Research (French: Organisation européenne pour la recherche nucléaire), known as CERN (/sɜːrn/; French pronunciation: [sɛʁn]; derived from the name Conseil européen pour la recherche nucléaire), is a European research organization that operates the largest particle physics laboratory in the world. Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border, and has 22 member states.[3] Israel is the only non-European country granted full membership.[4] CERN is an official United Nations Observer.[5]
The
acronym CERN is also used to refer to the laboratory, which in 2016 had
2,500 scientific, technical, and administrative staff members, and
hosted about 12,000 users. In the same year, CERN generated 49 petabytes of data.[6]
CERN's main function is to provide the particle accelerators and
other infrastructure needed for high-energy physics research – as a
result, numerous experiments have been constructed at CERN through international collaborations. The main site at Meyrin hosts a large computing facility, which is primarily used to store and analyse data from experiments, as well as simulate events. Researchers need remote access to these facilities, so the lab has historically been a major wide area network hub. CERN is also the birthplace of the World Wide Web.[7][8]
Member states | |
Formation | |
Headquarters | |
Membership | 22 countries. |
Official languages | |
Council President | |
Website | |
The convention establishing CERN was ratified on 29 September 1954 by 12 countries in Western Europe.[1] The acronym CERN originally represented the French words for Conseil Européen pour la Recherche Nucléaire (European
Council for Nuclear Research), which was a provisional council for
building the laboratory, established by 12 European governments in 1952.
The acronym was retained for the new laboratory after the provisional
council was dissolved, even though the name changed to the current Organisation Européenne pour la Recherche Nucléaire (European Organization for Nuclear Research) in 1954.
CERN's first president was Sir Benjamin Lockspeiser. Edoardo Amaldi was
the general secretary of CERN at its early stages when operations were
still provisional, while the first Director-General (1954) was Felix Bloch.[10]
The laboratory was originally devoted to the study of atomic nuclei, but was soon applied to higher-energy physics, concerned mainly with the study of interactions between subatomic particles. Therefore, the laboratory operated by CERN is commonly referred to as the European laboratory for particle physics (Laboratoire européen pour la physique des particules), which better describes the research being performed there.
Scientific achievements
Several important achievements in particle physics have been made through experiments at CERN. They include:
· 1989: The determination of the number of light neutrino families at the Large Electron–Positron Collider (LEP) operating on the Z boson peak;
In September 2011, CERN attracted media attention when the OPERA Collaboration reported the detection of possibly faster-than-light neutrinos.[19] Further tests showed that the results were flawed due to an incorrectly connected GPS synchronization cable.[20]
The 1984 Nobel Prize for Physics was awarded to Carlo Rubbia and Simon van der Meer for
the developments that resulted in the discoveries of the W and Z
bosons. The 1992 Nobel Prize for Physics was awarded to CERN staff
researcher Georges Charpak "for his invention and development of particle detectors, in particular the multiwire proportional chamber". The 2013 Nobel Prize for physics was awarded to François Englert and Peter Higgs for the theoretical description of the Higgs mechanism in the year after the Higgs boson was found by CERN experiments.
Computer science
History of the World Wide Web (www.com)
A plaque at CERN commemorating the invention of the World Wide Web by Tim Berners-Lee andRobert Cailliau
The World Wide Web began as a CERN project namedENQUIRE, initiated by Tim Berners-Lee in 1989 and Robert Cailliau in 1990.[21] Berners-Lee and Cailliau were jointly honoured by the Association for Computing Machinery in 1995 for their contributions to the development of the World Wide Web.
Based on the concept of hypertext,
the project was intended to facilitate the sharing of information
between researchers. The first website was activated in 1991. On
30 April 1993, CERN announced that the World Wide Web would be free to
anyone. A copy[22] of the original first webpage, created by Berners-Lee, is still published on the World Wide Web Consortium's website as a historical document.
Prior to the Web's development, CERN had pioneered the introduction of Internet technology, beginning in the early 1980s.[23]
More recently, CERN has become a facility for the development of grid computing, hosting projects including the Enabling Grids for E-sciencE (EGEE) and LHC Computing Grid. It also hosts the CERN Internet Exchange Point (CIXP), one of the two main internet exchange points in Switzerland.
Particle accelerators
List of current particle accelerators at CERN | |
Accelerates protons or ions | |
Accelerates protons or ions | |
Accelerates protons or ions | |
CERN operates
a network of six accelerators and a decelerator. Each machine in the
chain increases the energy of particle beams before delivering them to
experiments or to the next more powerful accelerator. Currently active
machines are:
· Two linear accelerators generate low energy particles. LINAC 2 accelerates protons to 50 MeV for injection into the Proton Synchrotron Booster (PSB), and LINAC 3 provides heavy ions at 4.2 MeV/u for injection into the Low Energy Ion Ring (LEIR).[24]
· The Proton Synchrotron Booster increases
the energy of particles generated by the proton linear accelerator
before they are transferred to the other accelerators.
· The Low Energy Ion Ring (LEIR) accelerates the ions from the ion linear accelerator, before transferring them to the Proton Synchrotron(PS). This accelerator was commissioned in 2005, after having been reconfigured from the previous Low Energy Antiproton Ring(LEAR).
·
· The 28 GeV Proton Synchrotron (PS), built during 1954—1959 and still operating as a feeder to the more powerful SPS.
· The Super Proton Synchrotron (SPS),
a circular accelerator with a diameter of 2 kilometres built in a
tunnel, which started operation in 1976. It was designed to deliver an
energy of 300 GeV and was gradually upgraded to 450 GeV. As well as
having its own beamlines for fixed-target experiments (currently COMPASS and NA62), it has been operated as a proton–antiproton collider (the SppS collider), and for accelerating high energy electrons and positrons which were injected into the Large Electron–Positron Collider (LEP). Since 2008, it has been used to inject protons and heavy ions into the Large Hadron Collider (LHC).
· The On-Line Isotope Mass Separator (ISOLDE), which is used to study unstable nuclei.
The radioactive ions are produced by the impact of protons at an energy
of 1.0–1.4 GeV from the Proton Synchrotron Booster. It was first
commissioned in 1967 and was rebuilt with major upgrades in 1974 and
1992.
· The Antiproton Decelerator (AD), which reduces the velocity of antiprotons to about 10% of the speed of light for research of antimatter.
· The Compact Linear Collider Test Facility, which studies feasibility for the future normal conducting linear collider project.
Large Hadron Collider
Many activities at CERN currently involve operating the Large Hadron Collider (LHC) and the experiments for it. The LHC represents a large-scale, worldwide scientific cooperation project.
The LHC tunnel is located 100 metres underground, in the region between the Geneva International Airport and the nearby Jura mountains.
The majority of its length is on the French side of the border. It uses
the 27 km circumference circular tunnel previously occupied by the Large Electron–Positron Collider (LEP),
which was shut down in November 2000. CERN's existing PS/SPS
accelerator complexes are used to pre-accelerate protons and lead ions
which are then injected into the LHC.
Seven experiments (CMS, ATLAS, LHCb, MoEDAL,[25] TOTEM, LHC-forward and ALICE)
are located along the collider; each of them studies particle
collisions from a different aspect, and with different technologies.
Construction for these experiments required an extraordinary engineering
effort. For example, a special crane was
rented from Belgium to lower pieces of the CMS detector into its
underground cavern, since each piece weighed nearly 2,000 tons. The
first of the approximately 5,000 magnets necessary for construction was
lowered down a special shaft at 13:00 GMT on 7 March 2005.
The LHC has begun to generate vast quantities of data, which CERN streams to laboratories around the world for distributed processing (making use of a specialized grid infrastructure, the LHC Computing Grid). During April 2005, a trial successfully streamed 600 MB/s to seven different sites across the world.
The initial particle beams were injected into the LHC August 2008.[26] The first beam was circulated through the entire LHC on 10 September 2008,[27] but the system failed 10 days later because of a faulty magnet connection, and it was stopped for repairs on 19 September 2008.
The LHC resumed operation on 20 November 2009 by successfully circulating two beams, each with an energy of 3.5 teraelectronvolts (TeV).
The challenge for the engineers was then to try to line up the two
beams so that they smashed into each other. This is like "firing two
needles across the Atlantic and getting them to hit each other"
according to Steve Myers, director for accelerators and technology.
On
30 March 2010, the LHC successfully collided two proton beams with 3.5
TeV of energy per proton, resulting in a 7 TeV collision energy.
However, this was just the start of what was needed for the expected
discovery of the Higgs boson.
When the 7 TeV experimental period ended, the LHC revved to 8 TeV (4
TeV per proton) starting March 2012, and soon began particle collisions
at that energy. In July 2012, CERN scientists announced the discovery of
a new sub-atomic particle that was later confirmed to be the Higgs boson.[28] In
March 2013, CERN announced that the measurements performed on the newly
found particle allowed it to conclude that this is a Higgs boson.[29] In
early 2013, the LHC was deactivated for a two-year maintenance period,
to strengthen the electrical connections between magnets inside the
accelerator and for other upgrades.
On
5 April 2015, after two years of maintenance and consolidation, the LHC
restarted for a second run. The first ramp to the record-breaking
energy of 6.5 TeV was performed on 10 April 2015.[30][31] In 2016, the design collision rate was exceeded for the first time.[32] A second two-year period of shutdown is scheduled to begin at the end of 2018.
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