Alkahest (or alcahest) is a hypothetical universal solvent, having the power to dissolve every other substance, including gold. It was much sought after by alchemists for its invaluable medicinal qualities. The name is believed to have been invented by Paracelsus (1493–1541), who modelled it on similar words taken from Arabic, such as ‘alkali’. Paracelsus' own recipe was based on caustic lime, alcohol, and carbonate of potash. In fact a universal solvent does not, and cannot, exist. The closest is likely to be aqua regia — or, depending ...

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A short-lived radioactive tracer isotope which decays by emitting a positron, chemically incorporated into a metabolically active molecule, is injected into the living subject (usually into blood circulation). There is a waiting period while the metabolically active molecule (usually a sugar) becomes concentrated in tissues of interest, then the subject is placed in the imaging scanner. The short-lived isotope decays, emitting a positron. After travelling up to a few millimeters the positron annihilates with an electron, producing a pair of ...

See also:

Positron emission tomography, Positron emission tomography - Description, Positron emission tomography - Applications, Positron emission tomography - PET scans safety

Read more here: » Positron emission tomography: Encyclopedia II - Positron emission tomography - Description

CERN is the Organisation Européenne pour la Recherche Nucléaire (European Organization for Nuclear Research ), the world's largest particle physics laboratory, situated on the border between France and Switzerland, just west of Geneva. It is also known for being the birthplace of the World Wide Web. The convention establishing it was signed on September 29, 1954. From the original 12 signatories of the CERN convention, membership ...

Including:

• CERN - The acronym
• CERN - The accelerator complex
• CERN - Scientific Achievements
• CERN - The accelerator of the future: the LHC
• CERN - Decommissioned accelerators
• CERN - CERN sites
• CERN - Computer Science and CERN
• CERN - Member States
• CERN - Public exhibits
• CERN - In Fiction

Read more here: » CERN: Encyclopedia - CERN

In physics, and specifically particle physics, CP violation is a violation of the postulated CP symmetry of the laws of physics. It plays an important role in theories of cosmology that attempt to explain the dominance of matter over antimatter in the present Universe. The discovery of CP violation in 1964 in the decays of neutral kaons resulted in the Nobel Prize in Physics in 1980 for its discoverers James Cronin and Val Fitch. The study of CP violation remains a vibrant area of theoretical and exp ...

Including:

• CP-violation - What is CP?
• CP-violation - CP Violation
• CP-violation - CP Violation and the Existence of the Universe

Read more here: » CP-violation: Encyclopedia - CP-violation

This is an incomplete list of some of the unsolved problems in physics. Some of these problems are theoretical, meaning that existing theories seem incapable of explaining some observed phenomenon or experimental result. Others are experimental, meaning that there is a difficulty in creating an experiment to test a proposed theory or investigate a phenomenon in greater detail. Lastly, some even border on the pseudo-sciences, e.g. the fringes of science which are widely discredited by today's community, but may some day show promise or ...

Including:

• Unsolved problems in physics - Phenomena in search of an explanation
• Unsolved problems in physics - Theoretical ideas in search of experimental evidence
• Unsolved problems in physics - Engineering challenges
• Unsolved problems in physics - Problems solved recently

Read more here: » Unsolved problems in physics: Encyclopedia - Unsolved problems in physics

Robert Scott Lazar (born 26 January 1959) is a central (and highly controversial) figure in discussions about UFOs. Lazar claims to have worked at area S-4 of the Nevada Test Site (near Area 51) at the special request of Edward Teller. He further claims to have performed reverse engineering on crashed extraterrestrial spacecraft there. The publicity surrounding his revelations is one of the major factors in putting the previousl ...

Including:

• Bob Lazar - Claims
• Bob Lazar - Criticisms of Lazar
• Bob Lazar - Reference

Read more here: » Bob Lazar: Encyclopedia - Bob Lazar

CPT symmetry is a fundamental symmetry of physical laws under transformations that involve the inversions of charge, parity and time simultaneously. Efforts in the late 1950s revealed the violation of P-symmetry by some phenomena that involve weak nuclear force fields, and there are well known violations of C-symmetry and T-symmetry as well. For a short time, the CP-symmetry was believed to be preserved by all physical phenomena, but that was later found to be false too. There is a theorem that derives the preservation of CPT symmetry for all of physical ...

Read more here: » CPT symmetry: Encyclopedia - CPT symmetry

ATLAS (A Toroidal LHC ApparatuS) is one of the five particle detector experiments (ALICE, ATLAS, CMS, TOTEM, and LHCb) being constructed at the Large Hadron Collider, a new particle accelerator at CERN in Switzerland. It will be 45 metres long and 25 metres in diameter, and will weigh about 7,000 tonnes. The project involves roughly 2,000 scientists and engineers at 151 institutions in 34 countries. The construction is scheduled to be completed in 2007. The experiment is expecte ...

Including:

• ATLAS experiment - Background
• ATLAS experiment - Physics program
• ATLAS experiment - Components
• ATLAS experiment - Inner Detector
• ATLAS experiment - Calorimeters
• ATLAS experiment - Muon spectrometer
• ATLAS experiment - Magnet system
• ATLAS experiment - Data systems and analysis

Read more here: » ATLAS experiment: Encyclopedia - ATLAS experiment

In physical cosmology, the Big Bang is the scientific theory that the Universe emerged from an enormously dense and hot state about 13.7 billion years ago. The Big Bang is a consequence of the observed Hubble's law velocities of distant galaxies that when taken together with the cosmological principle imply that space is expanding according to the Friedmann-Lemaître model of general relativity. Extrapolated into the past, these observations show that the Universe has expanded from a primeval state, in which all the matter and energy ...

Including:

• Big Bang - History
• Big Bang - Overview
• Big Bang - Theoretical underpinnings
• Big Bang - Observational evidence
• Big Bang - Hubble's law expansion
• Big Bang - Cosmic microwave background radiation
• Big Bang - Abundance of primordial elements
• Big Bang - Galactic evolution and distribution
• Big Bang - Features issues and problems
• Big Bang - Horizon problem
• Big Bang - Flatness problem
• Big Bang - Magnetic monopoles
• Big Bang - Baryon asymmetry
• Big Bang - Globular cluster age
• Big Bang - Dark matter
• Big Bang - Dark energy
• Big Bang - The future according to the Big Bang theory
• Big Bang - Speculative physics beyond the Big Bang
• Big Bang - Philosophical and religious interpretations

Read more here: » Big Bang: Encyclopedia - Big Bang

An atom (Greek άτομον from ά: non and τομον: divisible) is a submicroscopic structure found in all ordinary matter. It is the smallest unit of an element to retain all the chemical properties of that element. The word atom originally meant a smallest possible particle of matter, not further divisible. Later, the objects that had been called atoms were found to be further divisible into smaller subatomic particles, but the word a ...

Including:

• Atom - Properties of the atom
• Atom - Subatomic particles
• Atom - Atomic forces
• Atom - Atom size and speed
• Atom - Elements isotopes and ions
• Atom - Valence and bonding
• Atom - Atomic spectrum
• Atom - Atoms and antimatter
• Atom - Atoms and the Big Bang
• Atom - History of atomic theory
• Atom - Study of atoms

Read more here: » Atom: Encyclopedia - Atom

The USS Enterprise (NCC-1701-D), in the Star Trek fictional universe, is the Galaxy class starship that is the principal setting of the television series Star Trek: The Next Generation (TNG). The series is set in the late 24th century, when humans have allied with other friendly alien species to form the United Federation of Planets; events in TNG take place more than seventy years after those of the original Star Trek television series and related movies. USS Enterprise NCC-1701 ...

Including:

• USS Enterprise NCC-1701-D - Fictional history
• USS Enterprise NCC-1701-D - Design notes
• USS Enterprise NCC-1701-D - External link

Read more here: » USS Enterprise NCC-1701-D: Encyclopedia - USS Enterprise NCC-1701-D

Angels and Demons (2000) is a mystery novel by Dan Brown, featuring the character Robert Langdon, who is also the principal character of his subsequent, better-known novel The Da Vinci Code. The story involves a conflict between an ancient group, the Illuminati, and the Catholic Church. It is credited with being the first novel to contain ambigrams. Angels and Demons - Main characters. Robert Langdon: Protagonist, symbologist, professor Vittoria Vetra: CERN physici ...

Including:

• Angels and Demons - Main characters
• Angels and Demons - Plot
• Angels and Demons - Similarities to Brown's other books
• Angels and Demons - Common to two books
• Angels and Demons - Elements that are common to all four of Brown's books
• Angels and Demons - Facts and mythology behind the book
• Angels and Demons - The Altars of Science
• Angels and Demons - Factual inaccuracies
• Angels and Demons - The All Seeing Eye

Read more here: » Angels and Demons: Encyclopedia - Angels and Demons

Antihydrogen is the antimatter counterpart of hydrogen. Whereas the common hydrogen atom is composed of an electron and proton, the antihydrogen atom is made up of a positron and antiproton. Its (proposed) chemical symbol is H, that is, H with an overbar (pronounced aytch-bar; IPA representation [eɪtʃ ba:ɹ]). According to the CPT theorem (CPT stands for charge conjugation, parity reversal, and time/motion reversal) of ...

Read more here: » Antihydrogen: Encyclopedia - Antihydrogen

Corresponding to each kind of particle, there is an associated antiparticle with the same mass and spin. Some particles, such as the photon, are identical to their antiparticle; such particles must have no electric charge, but not all charge-neutral particles are of this kind. The laws of nature were thought to be symmetric between particles and antiparticles until CP violation experiments found that time-reversal symmetry is violated in nature. The observed excess of baryons over anti-baryons in the universe is ...

Including:

• Antiparticle - History
• Antiparticle - Experiment
• Antiparticle - Hole theory
• Antiparticle - Particle-antiparticle annihilation
• Antiparticle - Properties of antiparticles
• Antiparticle - Quantum field theory
• Antiparticle - The Feynman-Stueckelberg interpretation

Read more here: » Antiparticle: Encyclopedia - Antiparticle

Any explosive material has the following characteristics: It is chemically or otherwise energetically unstable. The initiation produces a sudden expansion of the material accompanied by the production of heat and large changes in pressure (and typically also a flash or loud noise) which is called the explosion. Explosive material - Chemical explosives. Explosives are classified as low or high explosives according to their rates of decomposition. Low explosives burn rapidly (or d ...

Including:

• Explosive material - Chemical explosives
• Explosive material - Explosive compatibility groupings
• Explosive material - Low Explosives
• Explosive material - High Explosives
• Explosive material - Composition of the material
• Explosive material - Chemical explosive reaction
• Explosive material - Formation of gases
• Explosive material - Evolution of heat
• Explosive material - Rapidity of reaction
• Explosive material - Initiation of reaction
• Explosive material - Sensitiser
• Explosive material - Military explosives
• Explosive material - Availability and cost
• Explosive material - Sensitivity
• Explosive material - Stability
• Explosive material - Power
• Explosive material - Brisance
• Explosive material - Density
• Explosive material - Volatility
• Explosive material - Hygroscopicity
• Explosive material - Toxicity
• Explosive material - Measurement of chemical explosive reaction
• Explosive material - Oxygen balance OB%
• Explosive material - Heat of explosion
• Explosive material - Balancing chemical explosion equations
• Explosive material - Volume of products of explosion
• Explosive material - Explosive strength
• Explosive material - Example of thermochemical calculations

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PET scanning is invasive, in that radioactive material is injected into the subject. However the total dose of radiation is small, usually around 7 mSv. This can be compared to 2.2 mSv average annual background radiation in the UK, 0.02 mSv for a chest X-Ray, up to 8 mSv for a CT scan of the chest, 2-6 mSv per annum for aircrew, and 7.8 mSv per annum background exposure in Cornwall (Data from UK National Radiological Protection Board). Because the half-life of 18F is about two hours, the prepared doses decay significantly d ...

See also:

Positron emission tomography, Positron emission tomography - Description, Positron emission tomography - Applications, Positron emission tomography - PET scans safety

Read more here: » Positron emission tomography: Encyclopedia II - Positron emission tomography - PET scans safety

Nearly Spock's entire Starfleet career — he joined Starfleet against his father's wishes, as Sarek wanted his son to attend the Vulcan Science Academy — was spent serving onboard a single ship, the famous starship USS Enterprise. The non-canon young adult novel 'Crisis on Vulcan' depicts Spock's first experience with the ship. He accompanies his father on a diplomatic mission aboard the Enterprise, and while there meets his future captain, Christopher Pike, then serving as the first officer under Robert April, the first captain of ...

See also:

Mr. Spock, Mr. Spock - Personal life, Mr. Spock - Early years, Mr. Spock - Starfleet, Mr. Spock - Rebirth, Mr. Spock - Later life, Mr. Spock - Abilities, Mr. Spock - Vulcan Nerve Pinch, Mr. Spock - Mind meld, Mr. Spock - The Mirror Spock, Mr. Spock - Trivia

Read more here: » Mr. Spock: Encyclopedia II - Mr. Spock - Starfleet

E=mc² applies to all objects with mass, as it is a statement that mass is derived from energy, or energy from mass, and it is possible to convert between the two, the princips of nuclear energy. Usually, this equation applies to an object that is not moving as seen from a reference point. But this same object can be moving from the standpoint of an other frame of reference, so that, for this latter frame, the equation still stands but the total energy (or equivalantly, mass) differs in amount to the former frame. So unlike Newtonian mechanics, in Special ...

See also:

E=mc², E=mc² - Meanings of the formula, E=mc² - Implications, E=mc² - Background and consequences, E=mc² - Applicability of the equation, E=mc² - Using relativistic mass, E=mc² - Using rest mass, E=mc² - Low energy approximation, E=mc² - Einstein and his 1905 paper, E=mc² - Contributions of others, E=mc² - Television biography

Read more here: » E=mc²: Encyclopedia II - E=mc² - Applicability of the equation

Karl Pearson was born in Islington, London on March 27, 1857, the son of barrister William Pearson and Fanny, née Smith. He was educated privately at University College School, after which he went to King's College, Cambridge to study mathematics. He then spent part of 1879 and 1880 studying medieval and 16th century German literature at the universities of Berlin and Heidelberg – in fact, he became sufficiently knowledgeable in this field that he was offered a post in the ...

See also:

Karl Pearson, Karl Pearson - Biography, Karl Pearson - Awards from professional bodies, Karl Pearson - Contributions to statistics, Karl Pearson - Publications

Read more here: » Karl Pearson: Encyclopedia II - Karl Pearson - Biography

Of the several hundred quasars observed, all spectra have shown considerable redshifts, ranging from 0.06 to the recent maximum of 6.4. Therefore, all known quasars lie at great distances from us, the closest being 240 Mpc away and the farthest being 5500 Mpc away. Most quasars are known to lie above 1000 Mpc in distance; since light takes such a long time to cover these great distances, we are seeing quasars as they existed long a ...

See also:

Quasar, Quasar - Properties of quasars, Quasar - Quasar emission generation, Quasar - History of quasar observation

Read more here: » Quasar: Encyclopedia II - Quasar - Properties of quasars