How was the matter created?
Gamov discovered that nuclear reactions gave birth to the lightest elements.
He said that all the elements were produced by the intense heat of the big
bang (nucleosynthesis). Starting with hydrogen, all the other elements of
the Mendeleev periodic chart could be produced by adding more particles
to the hydrogen atoms. In other words, due to the high temperature at the
time of the big bang, the protons of the hydrogen atoms are brought closely
together to form helium. In the same way, successive collisions would produce
all the other elements. This was true for lithium and beryllium but he soon
found out that it did not work for elements of mass 5 and 8. However he
was right with helium. It has been measured that tars and galaxies contain
25%ofhelium and 75% of hydrogen as foreseen by Gamov. This is the first
proof of the Big bang theory.
Fred Hoyle showed that the heavier elements/ up to iron, were produced inside the stars' hot core. But to produce the elements heavier than iron, even higher temperature were required. Hoyle showed that they were produced during the explosion of massive stars, or Supernova, where temperatures of trillions of degrees are the norm. These heavy elements were then ejected into space.
- Atom (Greek meaning "the smallest indivisible particle of matter): In chemistry and physics, it is the smallest particle still characterizing a chemical element.
- Atomic nucleus of an atom is the very small dense region of an atom, in its centre consisting of nucleons (protons and neutrons). Almost all of the mass in an atom is made up from the protons and neutrons in the nucleus with a very small contribution from the orbiting electrons.
- Bose-Einstein condensate (BEC): It is a state of matter of bosons confined in an external potential and cooled to temperatures very near to absolute zero. Under such supercooled conditions, a large fraction of the atoms collapse into the lowest quantum state of the external potential, at which point quantum effects become apparent on a macroscopic scale. The first gaseous condensate was produced in 1995 at the University of Colorado at Boulder, using a gas of rubidium atoms cooled to 170 nanokelvin.
- Cold dark matter (or CDM): It is a refinement of the big bang theory that contains the additional assumption that most of the matter in the Universe consists of material that cannot be observed by its electromagnetic radiation and hence is dark while at the same time the particles making up this matter are slow and hence are cold.
- Dark matter: It is a hypothetical form of matter of unknown composition that does not emit or reflect enough electromagnetic radiation to be observed directly, but whose presence can be inferred from gravitational effects on visible matter. Dark matter accounts for the vast majority of mass in the observable universe. Dark matter plays a central role in structure formation and galaxy evolution. All the evidences suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than that which interacts with electromagnetic radiation: the remainder is called the "dark matter component". The composition of dark matter is unknown, but may include ordinary and heavy neutrinos, recently postulated elementary particles such as WIMPs and axions, astronomical bodies such as dwarf stars and planets (collectively called MACHOs), primordial black holes and clouds of nonluminous gas. Also, matter which might exist in another universe but might affect ours via gravity would be consistent with some theories of brane cosmology. Current evidence favours models in which the primary component of dark matter is new elementary particles, collectively called non-baryonic dark matter.
- Dark energy: It is the name given to the antigravitating influence that is accelerating the rate of expansion of the universe. It is known not to be composed of known particles like protons, neutrons or electrons, nor of the particles of dark matter, because these all gravitate.
- Degenerate matter: It is matter which has sufficiently high density that the dominant contribution to its pressure rises from the Pauli Exclusion Principle. The pressure maintained by a body of degenerate matter is called the degeneracy pressure, and arises because the Pauli principle forbids the constituent particles to occupy identical quantum states. Any attempt to force them close enough together that they are not clearly separated by position must place them in different energy levels. Therefore, reducing the volume requires forcing many of the particles into higher-energy quantum states. This requires additional compression force, and is manifest as a resisting pressure.
- Di-positronium, or dipositronium: It is a molecule consisting of two atoms of positronium. The researchers made the positronium molecules by firing intense bursts of positrons into a thin film of porous silica, which is the chemical name for the mineral quartz. Upon slowing down in silica, the positrons were captured by ordinary electrons to form positronium atoms.
- Exotic atom: It is an otherwise normal atom in which one or more sub-atomic particles have been replaced by other particles of the same charge. For example, electrons may be replaced by other negatively charged particles such as muons (muonic atoms) or pions (pionic atoms). Because these substitute particles are usually unstable, exotic atoms typically have short lifetimes.
- Exotic matter: It is a hypothetical concept of particle physics. It covers any material which violates one or more classical conditions or is not made of known baryonic particles. Such materials would possess qualities like negative mass or being repelled rather than attracted by gravity. It is used in certain speculative theories, such as on the construction of wormholes. It can also refer to material composed of some form of exotic atom.
- Hot dark matter: It is a hypothetical form of dark matter which consists of particles that travel with ultrarelativistic velocities. The best candidate for the identity of hot dark matter is the neutrino. Neutrinos have very small masses, and do not partake in two of the four fundamental forces, the electromagnetic interaction and the strong interaction. They interact by the weak interaction, and gravity, but due to the feeble strength of these forces, they are difficult to detect.
- Isotopes are any of the several different forms of an element each having different atomic mass (mass number). Isotopes of an element have nuclei with the same number of protons (the same atomic number) but different numbers of neutrons. Therefore, isotopes have different mass numbers.
- Molecule: In chemistry it is defined as a sufficiently stable electrically neutral group of at least two atoms in a definite arrangement held together by strong chemical bonds.
- Negative mass: In Newton theory of gravity, there have been at least three conceptually distinct quantities called mass: inertial mass, "active" gravitational mass (that is, the source of the gravitational field), and "passive" gravitational mass (that is, the amount of force produced in response to gravity). The Einstein equivalence principle postulates that inertial mass must equal passive gravitational mass; while the law of conservation of momentum requires that active and passive gravitational mass must be identical. In considering hypothetical particles with negative mass, it is important to consider which of these concepts of mass are negative. In 1957, Hermann Bondi that mass might be negative as well as positive. He pointed out that this does not entail a logical contradiction, as long as all three forms of mass are all negative.
- Positronium (Ps): It is a system consisting of an electron and its anti-particle,
a positron, bound together into an "exotic atom". The orbit of
the two particles and the set of energy levels are similar to that of the
hydrogen atom (electron and proton). However, because of the reduced mass,
the frequencies associated with the spectral lines are less than half of
those of the corresponding hydrogen lines.