In cosmology, the cosmological constant problem or vacuum catastrophe is the disagreement between the observed values of vacuum energy density (the small value of the cosmological constant) and theoretical large value of zero-point energy suggested by quantum field theory.
Depending on the Planck energy cutoff and other factors, the discrepancy is as high as 120 orders of magnitude,[1] a state of affairs described by physicists as "the largest discrepancy between theory and experiment in all of science"[1] and "the worst theoretical prediction in the history of physics."[2]
https://en.wikipedia.org/wiki/Cosmological_constant_problem
In a supersymmetric theory the equations for force and the equations for matter are identical. In theoretical and mathematical physics, any theory with this property has the principle of supersymmetry (SUSY).
https://en.wikipedia.org/wiki/Supersymmetry
https://en.wikipedia.org/wiki/Photoelectric_effect
https://en.wikipedia.org/wiki/symmetry
https://en.wikipedia.org/wiki/mirror
https://en.wikipedia.org/wiki/observable_universe
https://en.wikipedia.org/wiki/Kirchhoff%27s_law_of_thermal_radiation
https://en.wikipedia.org/wiki/Radiance
https://en.wikipedia.org/wiki/Laser_cooling
https://en.wikipedia.org/wiki/Solar_constant
https://en.wikipedia.org/wiki/Poynting_vector
https://en.wikipedia.org/wiki/Simultaneous_multithreading
https://en.wikipedia.org/wiki/Hyper-threading
https://en.wikipedia.org/wiki/Radioactive_decay
https://en.wikipedia.org/wiki/Wet_sulfuric_acid_process
https://en.wikipedia.org/wiki/Contrast_effect
https://en.wikipedia.org/wiki/Flynn%27s_taxonomy#Array_Processor
https://en.wikipedia.org/wiki/Simultaneous_nitrification–denitrification
https://topex.ucsd.edu/rs/radiation.pdf
The significance of radiation pressure increases rapidly at extremely high temperatures and can sometimes dwarf the usual gas pressure, for instance, in stellar interiorsand thermonuclear weapons. Furthermore, large lasers operating in space have been suggested as a means of propelling sail craft in beam-powered propulsion.
Compression in a uniform radiation field[edit]
In general, the pressure of electromagnetic waves can be obtained from the vanishing of the trace of the electromagnetic stress tensor: since this trace equals 3P − u, we get
where u is the radiation energy per unit volume.
This can also be shown in the specific case of the pressure exerted on surfaces of a body in thermal equilibrium with its surroundings, at a temperature T: the body will be surrounded by a uniform radiation field described by the Planck black-body radiation law and will experience a compressive pressure due to that impinging radiation, its reflection, and its own black-body emission. From that it can be shown that the resulting pressure is equal to one third of the total radiant energy per unit volume in the surrounding space.[13][14][15][16]
By using Stefan–Boltzmann law, this can be expressed as
where is the Stefan–Boltzmann constant.
Solar radiation pressure[edit]
Solar radiation pressure is due to the Sun's radiation at closer distances, thus especially within the Solar System. (The radiation pressure of sunlight on Earth is very small: it is equivalent to that exerted by about a thousandth of a gram on an area of 1 square metre, or 10 μN/m2.) While it acts on all objects, its net effect is generally greater on smaller bodies, since they have a larger ratio of surface area to mass. All spacecraft experience such a pressure, except when they are behind the shadow of a larger orbiting body.
Solar radiation pressure on objects near the Earth may be calculated using the Sun's irradiance at 1 AU, known as the solar constant, or GSC, whose value is set at 1361 W/m2 as of 2011.[17]
All stars have a spectral energy distribution that depends on their surface temperature. The distribution is approximately that of black-body radiation. This distribution must be taken into account when calculating the radiation pressure or identifying reflector materials for optimizing a solar sail, for instance.
https://en.wikipedia.org/wiki/Radiation_pressure
Radiative transfer is the physical phenomenon of energy transfer in the form of electromagnetic radiation. The propagation of radiation through a medium is affected by absorption, emission, and scattering processes. The equation of radiative transfer describes these interactions mathematically. Equations of radiative transfer have application in a wide variety of subjects including optics, astrophysics, atmospheric science, and remote sensing. Analytic solutions to the radiative transfer equation (RTE) exist for simple cases but for more realistic media, with complex multiple scattering effects, numerical methods are required. The present article is largely focused on the condition of radiative equilibrium.[1] [2]
https://en.wikipedia.org/wiki/Radiative_transfer
Scattering is a term used in physics to describe a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectoryby localized non-uniformities (including particles and radiation) in the medium through which they pass.
https://en.wikipedia.org/wiki/Scattering
Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule is called an ion. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with electromagnetic radiation. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs. Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected.
https://en.wikipedia.org/wiki/Ionization
Internal conversion is a non-radioactive decay process wherein an excited nucleus interacts electromagnetically with one of the orbital electrons of the atom. This causes the electron to be emitted (ejected) from the atom.[1][2] Thus, in an internal conversion process, a high-energy electron is emitted from the radioactive atom, but not from the nucleus. For this reason, the high-speed electrons resulting from internal conversion are not called beta particles, since the latter come from beta decay, where they are newly created in the nuclear decay process.
Internal conversion is possible whenever gamma decay is possible, except in the case where the atom is fully ionised. During internal conversion, the atomic number does not change, and thus (as is the case with gamma decay) no transmutation of one element to another takes place.
https://en.wikipedia.org/wiki/Internal_conversion
High Energy Nuclear Physics, Nuclear Astrophysics, Nucleosynthesis, High Energy Processes, Capturing Processes, Nuclear Fission, Radioactive Decay, Nuclear Stability, etc..
Saturday, September 25, 2021
In chemistry, a radical is an atom, molecule, or ion that has sodium, iron, glucose, and unpaired valence electron.[1][2]
https://en.wikipedia.org/wiki/Radical_(chemistry)
In chemistry, a radical is an atom, molecule, or ion that has sodium, iron, glucose, and unpaired valence electron.[1][2]With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes.
A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉CH
2) which have two unpaired electrons.
Radicals may be generated in a number of ways, but typical methods involve redox reactions. Ionizing radiation, heat, electrical discharges, and electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations.
Radicals are important in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. A majority of natural products are generated by radical-generating enzymes. In living organisms, the radicals superoxide and nitric oxide and their reaction products regulate many processes, such as control of vascular tone and thus blood pressure. They also play a key role in the intermediary metabolism of various biological compounds. Such radicals can even be messengers in a process dubbed redox signaling. A radical may be trapped within a solvent cage or be otherwise bound.
https://en.wikipedia.org/wiki/Radical_(chemistry)
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