Dark matter has never been detected in the laboratory, and the particle physics nature of dark matter remains completely unknown.

Due to the smallness of Planck's constant it is practically impossible to realize experiments that directly reveal the wave nature of any system bigger than a few atoms but, in general, quantum mechanics considers all matter as possessing both particle and wave behaviors.

Specifically, if he / she chooses to determine the path, then he / she has no influence whatsoever over which of the two paths, the left one or the right one, nature will tell him / her is the one in which the particle is found.

The modern theory that explains the nature of light includes the notion of wave – particle duality.

More generally, the theory states that everything has both a particle nature and a wave nature, and various experiments can be done to bring out one or the other.

In particle physics, the electroweak interaction is the unified description of two of the four known fundamental interactions of nature: electromagnetism and the weak interaction.

In addition to their value as a mathematical tool, Feynman diagrams provide deep physical insight into the nature of particle interactions.

This would automatically predict the quantized nature and values of all elementary particle charges.

Light exerts physical pressure on objects in its path, a phenomenon which can be deduced by Maxwell's equations, but can be more easily explained by the particle nature of light: photons strike and transfer their momentum.

Just as each particle, by its nature, has a certain mass and charge, each has a certain magnetic moment, possibly zero.

Study of the photoelectric effect led to important steps in understanding the quantum nature of light and electrons and influenced the formation of the concept of wave – particle duality.

Every field theory of particle physics is based on certain symmetries of nature whose existence is deduced from observations.

In particle physics, the strong interaction ( also called the strong force, strong nuclear force, or color force ) is one of the four fundamental interactions of nature, the others being electromagnetism, the weak interaction and gravitation.

Over time, the term stuck in popularizations of quantum physics to describe a theory that would unify or explain through a single model the theories of all fundamental interactions and of all particles of nature: general relativity for gravitation, and the standard model of elementary particle physics — which includes quantum mechanics — for electromagnetism, the two nuclear interactions, and the known elementary particles.

In 1814, building on these results, Laplace famously suggested that a sufficiently powerful intellect could, if it knew the position and velocity of every particle at a given time, along with the laws of nature, calculate the position of any particle at any other time:

Beginning in 1670 and progressing over three decades, Isaac Newton developed and championed his corpuscular hypothesis, arguing that the perfectly straight lines of reflection demonstrated light's particle nature ; only particles could travel in such straight lines.

In fact, the modern explanation of the uncertainty principle, extending the Copenhagen interpretation first put forward by Bohr and Heisenberg, depends even more centrally on the wave nature of a particle: Just as it is nonsensical to discuss the precise location of a wave on a string, particles do not have perfectly precise positions ; likewise, just as it is nonsensical to discuss the wavelength of a " pulse " wave traveling down a string, particles do not have perfectly precise momenta ( which corresponds to the inverse of wavelength ).

The term also applies to photon counting in optical devices, where shot noise is associated with the particle nature of light.

There are many phenomena that result from either the particle or the wave nature of light.

Over time, the term stuck in popularizations of quantum physics to describe a theory that would unify or explain through a single model the theories of all fundamental interactions and of all particles of nature: general relativity for gravitation, and the standard model of elementary particle physics – which includes quantum mechanics – for electromagnetism, the two nuclear interactions, and the known elementary particles.

However, defining physical objects in terms of fundamental particles ( e. g. quarks ) leaves open the question of what is the nature of a fundamental particle and thus asks what categories of being can be used to explain physical objects.

This is a theoretically complicated dipole interaction which causes any extremely small uncharged particle to agglomerate with other small uncharged particles, or to stick to an uncharged surface.

The calibration of piezoelectric sensors in terms of the particle parameters is very uncertain.

This `` ejection '' momentum is linearly related to the particle energy.

The relationship between particle size and infectious dose is illustrated in Table 1.

A consequence of using waveforms to describe particles is that it is mathematically impossible to obtain precise values for both the position and momentum of a particle at the same time ; this became known as the uncertainty principle, formulated by Werner Heisenberg in 1926.

Though the word atom originally denoted a particle that cannot be cut into smaller particles, in modern scientific usage the atom is composed of various subatomic particles.

In quantum mechanics, where all particle momenta are associated with waves, it is the formation of such a wave packet which localizes the wave, and thus the particle, in space.

In states where a quantum mechanical particle is bound, it must be localized as a wave packet, and the existence of the packet and its minimum size implies a spread and minimal value in particle wavelength, and thus also momentum and energy.

In quantum mechanics, as a particle is localized to a smaller region in space, the associated compressed wave packet requires a larger and larger range of momenta, and thus larger kinetic energy.

An equivalent definition is the radius of an unperturbed circular Newtonian orbit about the Sun of a particle having infinitesimal mass, moving with an angular frequency of radians per day ; or that length such that, when used to describe the positions of the objects in the Solar System, the heliocentric gravitational constant ( the product GM < sub >☉</ sub >) is equal to ()< sup > 2 </ sup > AU < sup > 3 </ sup >/ d < sup > 2 </ sup >.

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle ( two protons and two neutrons ) and thereby transforms ( or ' decays ') into an atom with a mass number 4 less and atomic number 2 less.

Because an alpha particle is the same as a helium-4 nucleus, which has mass number 4 and atomic number 2, this can also be written as:

The alpha particle also has a charge + 2, but the charge is usually not written in nuclear equations, which describe nuclear reactions without considering the electrons.

Alpha decay is the most likely cluster decay because of the combined extremely high binding energy and relatively small mass of the helium-4 product nucleus ( the alpha particle ).

The alpha particle is trapped in a potential well by the nucleus.

The higher value for alpha radiation is generally attributable to the high linear energy transfer ( LET ) coefficient, which is about one ionization of a chemical bond for every angstrom of travel by the alpha particle.

In particle physics, antimatter is material composed of antiparticles, which have the same mass as particles of ordinary matter but have opposite charge and quantum spin.

Particle-antiparticle pairs can annihilate each other, producing photons ; since the charges of the particle and antiparticle are opposite, total charge is conserved.

Because charge is conserved, it is not possible to create an antiparticle without either destroying a particle of the same charge ( as in beta decay ) or creating a particle of the opposite charge.

Some agents have been shown to be much more toxic or infectious to experimental animals when exposed to aerosols of optimum particle size than by the natural portal.

For more details of this early work, see Alpha particle # History of discovery and use.

Dark energy in its simplest formulation takes the form of the cosmological constant term in Einstein's field equations of general relativity, but its composition and mechanism are unknown and, more generally, the details of its equation of state and relationship with the Standard Model of particle physics continue to be investigated both observationally and theoretically.

* Physical deformation of the particle ( e. g., stretching ) may increase the van der Waals forces more than stabilization forces ( such as electrostatic ), resulting coagulation of colloids at certain orientations.

Augustin-Jean Fresnel did more definitive studies and calculations of diffraction, made public in 1815 and 1818, and thereby gave great support to the wave theory of light that had been advanced by Christiaan Huygens and reinvigorated by Young, against Newton's particle theory.

Nonbaryonic dark matter is classified in terms of the mass of the particle ( s ) that is assumed to make it up, and / or the typical velocity dispersion of those particles ( since more massive particles move more slowly ).

Wave characteristics are more apparent when EM radiation is measured over relatively large timescales and over large distances while particle characteristics are more evident when measuring small timescales and distances.

Here, the unification of matter is even more complete, since the irreducible spinor representation 16 contains both the and 10 of SU ( 5 ) and a right-handed neutrino, and thus the complete particle content of one generation of the extended standard model with neutrino masses.

It is also partly responsible for the fact that the alpha particle is by far the most common type of baryonic particle to be ejected from atomic nuclei ; in other words, alpha decay is far more common than cluster decay.

A plasma enzyme called lecithin-cholesterol acyltransferase ( LCAT ) converts the free cholesterol into cholesteryl ester ( a more hydrophobic form of cholesterol ), which is then sequestered into the core of the lipoprotein particle, eventually making the newly synthesized HDL spherical.

Hyperbolas arise in practice in many ways: as the curve representing the function in the Cartesian plane, as the appearance of a circle viewed from within it, as the path followed by the shadow of the tip of a sundial, as the shape of an open orbit ( as distinct from a closed and hence elliptical orbit ), such as the orbit of a spacecraft during a gravity assisted swing-by of a planet or more generally any spacecraft exceeding the escape velocity of the nearest planet, as the path of a single-apparition comet ( one travelling too fast to ever return to the solar system ), as the scattering trajectory of a subatomic particle ( acted on by repulsive instead of attractive forces but the principle is the same ), and so on.

While no meson is stable, those of lower mass are nonetheless more stable than the most massive mesons, and are easier to observe and study in particle accelerators or in cosmic ray experiments.

The value of ' P ' can range from zero to nine, thus giving branes dimensions from zero ( 0-brane ≡ point particle ) to nine-five more than the world we are accustomed to inhabiting.

James Chadwick discovered a much more massive nuclear particle in 1932 and also named it a neutron, leaving two kinds of particles with the same name.

This excited state is unfavourable and the compound nucleus will almost instantaneously de-excite ( transmutate ) into a more stable configuration through the emission of a prompt particle and one or more characteristic prompt gamma photons.

Physicalism is also called " materialism ", but the term " physicalism " is preferable because it has evolved with the physical sciences to incorporate far more sophisticated notions of physicality than matter, for example wave / particle relationships and non-material forces produced by particles.

Higher energy particles more easily exhibit particle characteristics, while lower energy particles more easily exhibit wave characteristics.