is the Science
Physical Properties, Physical Laws and Phenomena.
refers to theories of physics that predate modern,
more complete, or more widely applicable theories. If a currently accepted
theory is considered to be "modern," and its introduction represented a
major paradigm shift
, then the previous theories, or new theories based on
the older paradigm, will often be referred to as belonging to the realm of
theoretical statement "inferred from particular
, applicable to a
defined group or class of phenomena, and expressible by the statement that
a particular phenomenon always occurs if certain conditions be present."
Physical laws are typically conclusions based on
repeated scientific experiments
over many years and which have become
accepted universally within the scientific community. The production of a
summary description of our environment in the form of such laws is a
fundamental aim of science. These terms are not used the same way by all
is any thing which manifests itself. Phenomena are
often, but not always, understood as "things that appear" or "experiences"
for a sentient being, or in principle may be so. To show, shine, appear, to
be manifest or manifest itself, plural phenomena) .
is the branch of physics that studies the
nature of the particles that constitute matter (particles with mass) and
radiation (massless particles).
is the field of physics that studies atoms
isolated system of electrons and an atomic nucleus. It is primarily
concerned with the arrangement of electrons
the nucleus and the processes by which these arrangements change. This
comprises ions, neutral atoms and, unless otherwise stated, it can be
assumed that the term atom includes ions.
is the field of physics that studies atomic
nuclei and their constituents and interactions. The most commonly known
application of nuclear physics is nuclear power generation, but the
research has led to applications in many fields, including nuclear
medicine and magnetic resonance imaging,
, ion implantation in materials engineering, and
radiocarbon dating in geology and archaeology.
the Study of Motion
is a collection of theoretical perspectives
based on the premise that the universe is, at heart, describable by
information. Therefore, according to this theory, the universe can be
conceived of as either the output of a deterministic or probabilistic
computer program, a vast, digital computation device, or mathematically
isomorphic to such a device.
refers to development of
to problems in physics.
employs mathematical models and
abstractions of physical objects and systems to rationalize, explain and
predict natural phenomena. This is in contrast to experimental physics,
which uses experimental tools to probe these phenomena.
is the category of disciplines and sub-disciplines in the
field of physics that are concerned with the
of physical phenomena and experiments
. Methods vary from
discipline to discipline, from simple experiments and observations, such
as the Cavendish experiment, to more complicated ones, such as the
Large Hadron Collider
Plasma can be created by heating a gas or subjecting it to a strong
electromagnetic field, applied with a laser
or microwave generator at temperatures above 5000 °C. This decreases or
increases the number of electrons in the atoms or molecules, creating
positive or negative charged particles called ions, and is accompanied by
the dissociation of molecular bonds, if present. Plasma is the most
abundant form of ordinary matter in the universe.
is the branch of
that employs the principles
of physics and chemistry "to ascertain the nature of the heavenly bodies,
rather than their positions or motions in space.
is an interdisciplinary science that applies the
approaches and methods of physics to study
. Biophysics covers all scales of biological
organization, from molecular to organismic and populations. Biophysical
research shares significant overlap with biochemistry, physical chemistry,
nanotechnology, bioengineering, computational biology, biomechanics and
is the minimum
amount of any physical entity involved in an interaction. The fundamental
notion that a physical property may be "quantized" is referred to as "the
". This means that the magnitude of the physical property
can take on only certain discrete values.
is a fundamental branch of physics concerned with
processes involving, for example, atoms and photons. Systems such as these
which obey quantum mechanics can be in a quantum superposition of
different states, unlike in classical physics.
also known as quantum physics or quantum theory),
including quantum field theory, is a fundamental branch of physics
concerned with processes involving, for example, atoms and photons.
such as these which obey quantum mechanics can be in a quantum
superposition of different states, unlike in classical physics.
is the theoretical framework for constructing quantum
mechanical models of subatomic particles in particle physics and
quasiparticles in condensed matter physics. QFT treats particles as
excited states of the underlying physical field, so these are called field
is a collection of techniques in quantum
field theory, the statistical mechanics of fields, and the theory of
self-similar geometric structures
are used to treat infinities arising in calculated quantities by altering
values of quantities to compensate for effects of their self-interactions.
(youtube) - Quantum Gravity
refers to the quantum mechanical
phenomenon where a particle tunnels through a barrier that it classically
could not surmount.
is the loss of
refers to applications of quantum mechanics
and theoretical chemistry to biological objects and problems.
is the relativistic quantum field
theory of electrodynamics. In essence, it describes how light and matter
interact and is the first theory where full agreement between quantum
mechanics and special relativity is achieved. QED mathematically describes
all phenomena involving electrically charged particles interacting by
means of exchange of photons and represents the quantum counterpart of
classical electromagnetism giving a complete account of matter and light
special relativity (SR) and general relativity (GR). It provides a
non-quantum mechanical description of a system of particles, or of a
fluid, in cases where the velocities of moving objects are comparable to
the speed of light c. As a result, classical mechanics is extended
correctly to particles traveling at high velocities and energies, and
provides a consistent inclusion of
with the mechanics of particles
is one of the two major sub-fields of
mechanics, along with quantum mechanics. Classical mechanics is concerned
with the set of physical laws describing the motion of bodies under the
influence of a system of forces. The study of the motion of bodies is an
ancient one, making classical mechanics one of the oldest and largest
subjects in science, engineering and technology. It is also widely known
as Newtonian mechanics.
states that the behavior of systems
described by the theory of quantum mechanics (or by the old quantum
theory) reproduces classical physics in the limit of large quantum
numbers. In other words, it says that for large orbits and for large
energies, quantum calculations must agree with classical calculations.
is an expression of the meaning of quantum mechanics that was largely
devised in the years 1925 to 1927 by Niels Bohr and Werner Heisenberg. It
remains one of the most commonly taught interpretations of quantum
Weak interaction, or weak nuclear force, responsible for radioactive
decay, which plays an essential role in
Strong interaction is the mechanism responsible for the strong nuclear
force (also called the strong force, nuclear strong force). At the range
, it is the strongest force, being approximately 137 times
stronger than electromagnetism, a million times stronger than weak
interaction and 1038 times stronger than gravitation. The strong nuclear
force ensures the stability of ordinary matter, confining quarks into
hadron particles, such as the proton and neutron, and the further binding
of neutrons and protons into atomic nuclei. Most of the mass-energy of a
common proton or neutron is in the form of the strong force field energy;
the individual quarks provide only about 1% of the mass-energy of a
3: Electromagnetic Force
A type of physical interaction that occurs between
All things with energy
are brought toward (or
gravitate toward) one another, including stars
and even light
Descriptions are not Explanations
is a theory concerning the electromagnetic, weak, and
strong nuclear interactions, as well as classifying all the subatomic
are a class of Feynman diagrams which are important
for understanding CP violating processes in the standard model. They refer
to one-loop processes in which a quark temporarily changes flavor (via a W
or Z loop), and the flavor-changed quark engages in some tree interaction,
typically a strong one. For the interactions where some quark flavors
(e.g. very heavy ones) have much higher interaction amplitudes than
others, such as CP-violating or Higgs interactions, these penguin
processes may have amplitudes comparable to or even greater than those of
the direct tree processes. A similar diagram can be drawn for leptonic
was an assumption that the same
and processes that operate in the universe now have
always operated in the universe in the past and apply everywhere in the
4 Fundamental States of Matter
is one of the four fundamental states of matter (the others being
solid, liquid, and plasma). A pure gas may be made up of individual atoms
(e.g. a noble gas like neon), elemental molecules made from one type of
atom (e.g. oxygen), or compound molecules made from a variety of atoms
(e.g. carbon dioxide). A gas mixture would contain a variety of pure gases
much like the Air
distinguishes a gas from liquids and solids is the vast separation of the
individual gas particles. This separation usually makes a colorless gas
invisible to the human observer. The interaction of gas particles in the
presence of electric and gravitational fields are considered negligible as
indicated by the constant velocity vectors in the image. One type of
commonly known gas is steam.2:
is one of the four
fundamental states of matter (the others being liquid, gas, and plasma).
It is characterized by structural rigidity and resistance to changes of
shape or volume. Unlike a liquid, a solid object
does not flow to take on
the shape of its container, nor does it expand to fill the entire volume
available to it like a gas does. The atoms in a solid are tightly bound to each other, either in a regular geometric lattice (crystalline solids,
which include metals and ordinary ice) or irregularly (an amorphous solid
such as common window glass).3:
is a nearly
incompressible fluid that conforms to the shape of its container but
retains a (nearly) constant volume independent of pressure. As such, it is
one of the four fundamental states of matter (the others being solid, gas,
and plasma), and is the only state with a definite volume but no fixed
shape. A liquid is made up of tiny vibrating particles of matter, such as
atoms, held together by intermolecular bonds. Water
is, by far, the most
common liquid on Earth. Like a gas, a liquid is able to flow and take
the shape of a container. Most liquids resist compression, although others
can be compressed. Unlike a gas, a liquid does not disperse to fill every
space of a container, and maintains a fairly constant density. A
distinctive property of the liquid state is surface tension, leading to
is one of the four fundamental states of matter, the others being solid,
liquid, and gas. A plasma has properties unlike those of the other states.
A plasma can be created by heating a gas or subjecting it to a strong
, applied with a Laser
or microwave generator. This
decreases or increases the number of electrons, creating positive or
negative charged particles called ions, and is accompanied by the
dissociation of molecular bonds, if present.
Where does laser energy go after being fired into plasma?
State of Matter
is one of the distinct forms that matter takes on. Four states of matter
are observable in everyday life: solid, liquid, gas, and plasma. Pyramid of
is a region of space (a thermodynamic system),
throughout which all physical properties of a material are essentially
uniform. Examples of physical properties include density, index of
refraction, magnetization and chemical composition. A simple description
is that a phase is a region of material that is chemically uniform,
physically distinct, and (often) mechanically separable. In a system
consisting of ice and water in a glass jar, the ice cubes are one phase,
the water is a second phase, and the humid air over the water is a third
phase. The glass of the jar is another separate phase.
is something which has mass and occupies
) and anything made
up of these, but not other energy phenomena or waves such as light or
nearly all matter that may be encountered or
experienced in everyday life is baryonic matter, which includes atoms of
any sort, and provides those with the property of mass. Non-baryonic
matter, as implied by the name, is any sort of matter that is not composed
primarily of baryons. This might include neutrinos and free electrons,
dark matter, such as supersymmetric
particles, axions, and black holes.
is a composite subatomic particle made up of three
is any property that is measurable, whose value
describes a state of a physical system. The changes in the physical
properties of a system can be used to describe its
transformations or evolutions
between its momentary states. Physical properties are often referred to as
observables. They are not modal properties. Quantifiable physical property
is called physical quantity.
is matter which has the
ability to change
properties (shape, density, moduli, conductivity, optical properties,
etc.) in a programmable fashion, based upon user input or autonomous
sensing. Programmable matter is thus linked to the concept of a material
which inherently has the ability to perform information processing.
Does Matter Die
is a material composed of antiparticles, which have the same mass as
particles of ordinary matter, but opposite charges, lepton numbers, and
baryon numbers. Mass
property of a body that causes it to have weight in a gravitational field.
Join together into a mass or collect or form a mass.
property of a physical body. It is the measure of an object's resistance
(a change in its state of motion) when a net force is applied. It also
determines the strength of its mutual gravitational attraction to other
bodies. The basic SI unit of mass is the kilogram (kg). Mass is not the
same as weight, even though we often calculate an object's mass by
measuring its weight with a spring scale, rather than comparing it
directly with known masses. An object on the Moon would weigh less than it
does on Earth because of the lower gravity, but it would still have the
same mass. This is because weight is a force, while mass is the property
that (along with gravity) determines the strength of this
Mass Energy Equivalence
states that anything having mass has
an equivalent amount of energy and vice versa, with these fundamental
quantities directly relating to one another by Albert Einstein's famous
formula: E=mc2 -
are manifestations of the same thing?
, the mass of an object is often referred to as
its weight, though these are in fact different concepts and quantities. In
scientific contexts, mass refers loosely to the amount of "matter" in an
object (though "matter" may be difficult to define), whereas weight refers
to the force exerted on an object by gravity. In other words, an object
with a mass of 1.0 kilogram will weigh approximately 9.81 newtons on the
surface of the Earth (its mass multiplied by the gravitational field
strength). (The newton is a unit of force, while the kilogram is a unit of
is a characteristic of the total energy
object or a system of objects that is the same in all frames of reference
related by Lorentz transformations. If a center of momentum frame exists
for the system, then the invariant mass of a system is simply the total
energy divided by the speed of light squared
In other reference frames, the energy of the system increases, but system
momentum is subtracted from this, so that the invariant mass remains
is a hypothetical concept of matter whose mass is of
opposite sign to the mass of normal matter, e.g. −2 kg. Such matter would
violate one or more energy conditions and show some strange properties,
stemming from the ambiguity as to whether attraction should refer to force
or the oppositely oriented acceleration for negative mass. It is used in
certain speculative theories, such as on the construction of wormholes.
The closest known real representative of such exotic matter is a region of
pseudo-negative pressure density produced by the
, which are physical forces arising from a
, which is the process of transition from a classical
understanding of physical phenomena to a newer understanding known as
quantum mechanics. It is a procedure for constructing a quantum field
theory starting from a classical field theory.
‘Negative mass’ created at Washington State University
is a concept used in physics to explain the nature of
certain fields, including the gravitational
and a number of quantum field effects. In more speculative
theories, negative energy is involved in wormholes which allow time travel
and warp drives for faster-than-light space travel.
- Minerals Mind over Matter
Atoms - Matter - Tiny Particles
is the smallest
constituent unit of ordinary
that has the properties of a
. Every solid,
liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are
; typical sizes are around 100 pm (a ten-billionth of a meter,
in the short scale). However, atoms do not have well-defined boundaries,
and there are different ways to define their size that give different
but close values. All Atoms have at least one proton in their core, and
the number of protons determines which kind of
an atom is. All atoms have electrons
negatively charged particles
that move around in
the space surrounding the positively-charged nuclear core.
proton, one electron and no neutrons.
is a scientific theory of the nature of
matter, which states that matter is composed of discrete units called
is a natural
that developed in several ancient traditions. The atomists
theorized that nature consists of two fundamental principles: atom and
. Unlike their modern scientific namesake in atomic theory,
philosophical atoms come in an infinite variety of shapes and sizes, each
indestructible, immutable and surrounded by a void where they collide with
the others or hook together forming a cluster. Clusters of different
shapes, arrangements, and positions give rise to the various macroscopic
substances in the world.
Sound of an Atom
(youtube)How many Atoms
in a Single Drop of Water?
"Weighing" Atoms with Electrons
If a single atom were the size of
would be the size of your
, and the
circling the stadium would be invisible. An atom is 99.9% empty
The nucleus accounts for 99.9% of an
The atoms in your
body are 99.9% empty space and none of them are the ones that you were born
with. So why do I feel
? Elementary particles have mass and
the space between elementary particles is filled with the
that also has the properties of mass.
is the energy required to disassemble a whole system into
separate parts. A bound system typically has a lower potential energy than
the sum of its constituent parts; this is what keeps the system together.
Often this means that energy
is released upon
the creation of a bound state. This definition corresponds to a positive
Essentially everything that you see in the world, including
yourself, is made of just three particles of matter — protons, neutrons
and electrons — interacting through a handful of forces — gravity,
and the nuclear forces.
Atoms are so much smaller
than the wavelength of visible light that the two don’t really
Atoms are invisible to light itself. Even the most powerful
light-focusing microscopes can’t visualize single atoms.
is the random motion of particles suspended
in a fluid (a liquid or a gas) resulting from their collision with the
fast-moving atoms or molecules in the gas or liquid.
is the force between protons and neutrons, subatomic
particles that are collectively called nucleons. The nuclear force is
responsible for binding protons and neutrons into atomic nuclei. Neutrons
and protons are affected by the nuclear force almost identically. Since
protons have charge +1 e, they experience a strong electric field
repulsion (following Coulomb's law) that tends to push them apart, but at
short range the attractive nuclear force overcomes the repulsive
electromagnetic force. The mass of a nucleus is less than the sum total of
the individual masses of the protons and neutrons which form it. The
difference in mass between bound and unbound nucleons is known as the mass
defect. Energy is released when some large nuclei break apart, and it is
this energy that is used in nuclear power and nuclear weapons.
is a subatomic
particle, symbol p or p+, with a positive electric charge of +1e
elementary charge and mass slightly less than that of a neutron. Protons
and neutrons, each with masses of approximately one atomic mass unit, are
collectively referred to as "nucleons". One or more protons are present in
the nucleus of every atom. They are a necessary part of the nucleus. The
number of protons in the nucleus is the defining property of an element,
and is referred to as the atomic number (represented by the symbol Z).
is a subatomic particle, symbol n or n0, with no net electric
charge and a mass slightly larger than that of a proton. Protons and
neutrons, each with mass approximately one atomic mass unit, constitute
the nucleus of an atom, and they are collectively referred to as nucleons.
Their properties and interactions are described by nuclear physics.
subatomic particle, symbol e−orβ
−, with a negative elementary electric
charge. Electrons belong to the first generation of the lepton particle
family, and are generally thought to be elementary particles because they
have no known components or substructure. The electron has a mass that is
approximately 1/1836 that of the proton. Quantum mechanical properties of
the electron include an intrinsic angular momentum (spin) of a
half-integer value, expressed in units of the reduced Planck constant, ħ.
As it is a fermion, no two electrons can occupy the same quantum state, in
accordance with the Pauli exclusion principle. Like all matter, electrons
have properties of both particles and waves: they can collide with other
particles and can be diffracted like light. The wave properties of
electrons are easier to observe with experiments than those of other
particles like neutrons and protons because electrons have a lower mass
and hence a larger De Broglie wavelength for a given energy.
is the area that electrons orbit in around an atom's
can contain only a fixed number of electrons: The first
shell can hold up to two electrons, the second shell can hold up to eight
(2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so
on. The general formula is that the nth shell can in principle hold up to
2(n2) electrons. Since electrons are electrically attracted to the
nucleus, an atom's electrons will generally occupy outer shells only if
the more inner shells have already been completely filled by other
electrons. However, this is not a strict requirement: atoms may have two
or even three incomplete outer shells. The
is the outermost shell of an atom in its uncombined
state, which contains the electrons most likely to account for the nature
of any reactions involving the atom and of the bonding interactions it has
with other atoms. Care must be taken to note that the outermost shell of
an ion is not commonly termed valence shell. Electrons in the valence
shell are referred to as valence electrons.
is an electron that is associated with an atom, and
that can participate in the formation of a chemical bond; in a single
covalent bond, both atoms in the bond contribute one valence electron in
order to form a shared pair. The presence of valence electrons can
determine the element's chemical properties and whether it may bond with
other elements: For a main group element, a valence electron can exist
only in the outermost electron shell. In a transition metal, a valence
electron can also be in an inner shell.
is an element
whose atom has a partially filled d sub-shell, or which can give rise to
cations with an incomplete d sub-shell". Or any element in the d-block of
the periodic table, which includes groups 3 to 12 on the periodic table.
In actual practice, the f-block lanthanide and actinide series are also
considered transition metals and are called "inner transition metals".
is the distribution of electrons of an atom or
(or other physical
structure) in atomic or molecular orbitals
occurs when an electron relocates from an atom or
molecule) to another such chemical entity. ET is a mechanistic description
of a redox reaction, wherein the oxidation state of reactant and product
is a chemical entity that donates electrons to another
compound. It is a reducing agent that, by virtue of its donating
electrons, is itself oxidized in the process.
a complete and irreversible transfer of one or more
electrons, not completely transferred, but results in an electron
resonance between the donor and acceptor. The microbes aren’t eating naked
electrons. Electrons traverse the entire distance of the membrane
tells us that
electrons have both wave and particle-like properties.
is a quantum mechanical effect. A tunneling current occurs
when electrons move through a barrier that they classically shouldn't be
able to move through. In classical terms, if you don't have enough energy
to move "over" a barrier, you won't. However, in the quantum mechanical
world, electrons have wavelike properties. These waves don’t end abruptly
at a wall or barrier, but taper off quickly. If the barrier is thin
enough, the probability function may extend into the next region, through
the barrier! Because of the small probability of an electron being on the
other side of the barrier, given enough electrons, some will indeed move
through and appear on the other side. When an electron moves through the
barrier in this fashion, it is called tunneling.
is the antiparticle or the antimatter
is the antimatter counterpart of Hydrogen
. Whereas the common
is composed of an electron and proton, the antihydrogen atom is made
up of a positron and antiproton. Scientists hope studying antihydrogen may
shed light on the question of why there is more matter than antimatter in
the universe, known as the baryon asymmetry problem. Antihydrogen is
produced artificially in particle accelerators. In 1999, NASA gave a cost
estimate of $62.5 trillion per gram of antihydrogen (equivalent to $90
trillion today), making it the most expensive material to produce. This is
due to the extremely low yield per experiment, and high opportunity cost
of using a particle accelerator.
of a particular chemical element which differ in neutron number. All
isotopes of a given element have the same number of protons in each atom.
The number of protons within the atom's nucleus is called atomic number
and is equal to the number of electrons in the neutral (non-ionized
atom. Each atomic number identifies a specific element, but not the
isotope; an atom of a given element may have a wide range in its number of
neutrons. The number of nucleons (both protons and neutrons) in the
nucleus is the atom's mass number, and each isotope of a given element has
a different mass number. For example, carbon-12, carbon-13 and carbon-14
are three isotopes of the element carbon with mass numbers 12, 13 and 14
respectively. The atomic number of carbon is 6, which means that every
carbon atom has 6 protons, so that the neutron numbers of these isotopes
are 6, 7 and 8 respectively.
is an atom or a
molecule in which the total number of electrons is not equal to the total
number of protons, giving the atom or molecule a net positive or negative
electrical charge. Ions can be created, by either chemical or physical
means, via ionization.
positively charged ion.
is the process by which an atom or a molecule
acquires a negative or positive charge by gaining or losing electrons to
form ions, often in conjunction with other chemical changes. 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 light. 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.
is radiation that carries enough energy
to free electrons from atoms or molecules, thereby ionizing them. Ionizing
radiation is made up of energetic subatomic particles, ions or atoms
moving at high speeds (usually greater than 1% of the speed of light), and
high-energy end of the electromagnetic
a contraction of the name for a chemical reduction–oxidation reaction. Any
such reaction involves both a reduction process and a complementary
oxidation process. Redox reactions include all chemical reactions in which
atoms have their oxidation state changed; in general, redox reactions
involve the transfer of electrons between chemical species.
We have just worked out what atoms
are, and we’ve realized that they are marvelously complex
structures that can undergo amazing changes, many of which occur
naturally. And by studying atoms this way, we’ve been able to
improve our technologies, harness the energy of nuclear
reactions and better understand the natural world around us.
We’ve also been able to better protect ourselves from radiation
and discover how materials change when placed under extreme
is a minute fragment or quantity of matter. In the physical sciences, a
particle is a small localized object to which can be ascribed several
physical or chemical properties such as volume or mass. They vary greatly
in size, from subatomic particles like the electron, to microscopic
particles like atoms and molecules, to macroscopic particles like powders
and other granular materials. Particles can also be used to create
scientific models of even larger objects, such as humans moving in a crowd
or celestial bodies in motion.
List of Particles
Particles of the Standard Model
is a hypothetical scalar particle that couples to matter
more weakly than gravity, postulated as a dark energy candidate. Due to a
non-linear self-interaction, it has a variable effective mass which is an
increasing function of the ambient energy density—as a result, the range
of the force mediated by the particle is predicted to be very small in
regions of high density (for example on Earth, where it is less than 1mm)
but much larger in low-density intergalactic regions: out in the cosmos
chameleon models permit a range of up to several thousand parsecs. As a
result of this variable mass, the hypothetical fifth force mediated by the
chameleon is able to evade current constraints on equivalence principle
violation derived from terrestrial experiments even if it couples to
matter with a strength equal or greater than that of gravity. Although
this property would allow the chameleon to drive the currently observed
acceleration of the universe's expansion, it also makes it very difficult
to test for experimentally.
is a transient fluctuation that exhibits many of the characteristics of an
ordinary particle, but that exists for a limited time. The concept of
virtual particles arises in perturbation theory of quantum field theory
where interactions between ordinary particles are described in terms of
exchanges of virtual particles. Any process involving virtual particles
admits a schematic representation known as a Feynman diagram, in which
virtual particles are represented by internal lines.
is a speculative theory that conjectures a form of matter that cannot be
explained in terms of particles using the Standard Model of particle
physics, because its components are scale invariant.
are particles much smaller than atoms. There are two types of
subatomic particles: elementary particles, which according to current
theories are not made of other particles; and composite particles.
Particle physics and nuclear physics study these particles and how they
is a particle whose substructure is unknown; thus, it is
unknown whether it is composed of other particles. Known elementary
particles include the fundamental fermions (quarks, leptons, antiquarks,
and antileptons), which generally are "matter particles" and "antimatter
particles", as well as the fundamental bosons (gauge bosons and the Higgs
boson), which generally are "force particles" that mediate interactions
among fermions. A particle containing two or more elementary particles is
a composite particle. (Fundamental Particle).
is a composite subatomic particle made up of three quarks (a triquark, as
distinct from mesons, which are composed of one quark and one antiquark).
is an elementary particle and a fundamental
constituent of matter. Quarks combine to form composite particles called
hadrons, the most stable of which are protons and neutrons, the components
of atomic nuclei. Due to a phenomenon known as color confinement, quarks
are never directly observed or found in isolation; they can be found only
within hadrons, such as baryons (of which protons and neutrons are
examples) and mesons. For this reason, much of what is known about quarks
has been drawn from observations of the hadrons themselves.
is one of the particles that make up the atomic
nucleus. Each atomic nucleus consists of one or more nucleons, and each
atom in turn consists of a cluster of nucleons surrounded by one or more
electrons. There are two known kinds of nucleon: the neutron and the
proton. The mass number of a given atomic isotope is identical to its
number of nucleons. Thus the term nucleon number may be used in place of
the more common terms mass number or atomic mass number.
is a fermion
(an elementary particle with half-integer spin) that interacts only via
the weak subatomic force and gravity. The mass of the neutrino is much
smaller than that of the other known elementary particles.
is an electron antineutrino emitted in β−decay
of a radionuclide naturally occurring in the Earth. Neutrinos, the
lightest of the known subatomic particles, lack measurable electromagnetic
properties and interact only via the weak nuclear force when ignoring
particle characterized by Fermi–Dirac statistics.
is an elementary, half-integer spin (spin 1⁄2)
particle that does not undergo strong interactions. Two main classes of
leptons exist: charged leptons (also known as the electron-like leptons),
and neutral leptons (better known as neutrinos). Charged leptons can
combine with other particles to form various composite particles such as
atoms and positronium, while neutrinos rarely interact with anything, and
are consequently rarely observed. The best known of all leptons is the
is the hypothetical supersymmetric partner of a gluon. Should they exist,
gluinos are expected by supersymmetry theorists to be pair produced in
particle accelerators such as the Large Hadron Collider.
is a state of matter in quantum chromodynamics
(QCD) which exists at extremely high temperature and/or density. This
state is thought to consist of asymptotically free quarks and gluons,
which are several of the basic building blocks of matter. It is believed
that up to a few milliseconds after the Big Bang, known as the Quark
epoch, the Universe was in a quark–gluon plasma state. In June 2015, an
international team of physicists produced quark-gluon plasma at the Large
Hadron Collider by colliding protons with lead nuclei at high energy
inside the supercollider’s Compact Muon Solenoid detector. They also
discovered that this newly produced state of matter behaves like a fluid.
are elementary particles that act as the exchange particles (or gauge
bosons) for the strong force between quarks, analogous to the exchange of
photons in the electromagnetic force between two charged particles. In lay
terms, they "glue" quarks together, forming protons and neutrons.
is an elementary particle similar to the electron, with an electric charge
of −1 e and a spin of 1/2, but with a much greater mass. It is classified
as a lepton. As is the case with other leptons, the muon is not believed
to have any sub-structure—that is, it is not thought to be composed of any
are a large family of hypothetical particles, each
particle consisting of six quarks or antiquarks of any flavours. Six
constituent quarks in any of several combinations could yield a colour
charge of zero; for example a hexaquark might contain either six quarks,
resembling two baryons bound together (a dibaryon), or three quarks and
three antiquarks. Once formed, dibaryons are predicted to be fairly stable
by the standards of particle physics. In 1977 Robert Jaffe proposed that a
possibly stable H dibaryon with the quark composition udsuds could
notionally result from the combination of two uds hyperons.
refers to a species of an elementary particle. The
Standard Model counts six flavours of quarks and six flavours of leptons.
They are conventionally parameterized with flavour quantum numbers that
are assigned to all subatomic particles, including composite ones. For
hadrons, these quantum numbers depend on the numbers of constituent quarks
of each particular flavour.
is a hypothetical particle consisting of a bound
state of roughly equal numbers of up, down, and strange quarks. An
equivalent description is that a strangelet is a small fragment of strange
matter, small enough to be considered a particle. The size of an object
composed of strange matter could, theoretically, range from a few
femtometers across (with the mass of a light nucleus) to arbitrarily
large. Once the size becomes macroscopic (on the order of metres across),
such an object is usually called a strange star. The term "strangelet"
originates with Edward Farhi and R. L. Jaffe. Strangelets have been
suggested as a dark matter candidate.
is a hypothetical subatomic particle, the fermion WIMP superpartner of the
photon predicted by supersymmetry. It is an example of a gaugino. Even
though no photino has ever been observed so far, it is expected to be the
lightest stable particle in the universe. It is proposed that photinos are
produced by sources of ultra-high-energy cosmic rays.
is a theoretical framework in which the point-like
particles of particle physics are replaced by one-dimensional objects
called strings. It describes how these strings propagate through space and
interact with each other. On distance scales larger than the string scale,
a string looks just like an ordinary particle, with its mass, charge, and
other properties determined by the vibrational state of the string. In
string theory, one of the many vibrational states of the string
corresponds to the graviton, a quantum mechanical particle that carries
gravitational force. Thus string theory is a theory of quantum gravity.
is an attempt to explain all of the
particles and fundamental forces of nature in one theory by modelling them
as vibrations of tiny supersymmetric strings.
is a theory in physics that unifies all consistent versions of superstring
theory. The existence of such a theory was first conjectured by Edward
Witten at a string theory conference at the University of Southern
California in the spring of 1995. Witten's announcement initiated a flurry
of research activity known as the second superstring revolution.
Introduction to M-theory
presents an idea about the basic substance of the universe. So far no
experimental evidence exists showing that M-theory is a description of the
real world. Interest in this theory is mainly driven by mathematical
is the value of the energy density of
the vacuum of space.
Theory of Everything
is a hypothetical single, all-encompassing, coherent theoretical
framework of physics that fully explains and links together all physical
aspects of the universe. Finding a ToE is one of the major unsolved
problems in physics.
Alternatives to General Relativity
are physical theories that attempt to describe the phenomena of
gravitation in competition to Einstein's theory of general relativity.
a hypothetical elementary particle that mediates the force of gravitation
in the framework of quantum field theory.
Unified Field Theory
is a type of field theory that allows
all that is usually thought of as fundamental forces and elementary
particles to be written in terms of a single field.
is a partial differential equation which
determines the dynamics of a physical field, specifically the time
evolution and spatial distribution of the field. The solutions to the
equation are mathematical functions which correspond directly to the
field, as a functions of time and space. Since the field equation is a
partial differential equation, there are families of solutions which
represent a variety of physical possibilities. Usually, there is not just
a single equation, but a set of coupled equations which must be solved
simultaneously. Field equations are not ordinary differential equations
since a field depends on space and time, which requires at least two
Interference Wave Propagation
is a phenomenon in which two
waves superpose to form a resultant wave of greater, lower, or the same
amplitude. Interference usually refers to the interaction of waves that
are correlated or coherent with each other, either because they come from
the same source or because they have the same or nearly the same
frequency. Interference effects can be observed with all types of waves,
for example, light, radio, acoustic, surface water waves or matter waves.
two wave sources are perfectly coherent if they
have a constant phase difference and the same frequency. It is an ideal
property of waves that enables stationary (i.e. temporally and spatially
constant) interference. It contains several distinct concepts, which are
limiting cases that never quite occur in reality but allow an
understanding of the physics of waves, and has become a very important
concept in quantum physics. More generally, coherence describes all
properties of the correlation between physical quantities of a single
wave, or between several waves or wave packets.
is a relativistic wave equation derived by
British physicist Paul Dirac in 1928. In its free form, or including
electromagnetic interactions, it describes all spin-1/2 massive particles
such as electrons and quarks for which parity is a symmetry. It is
consistent with both the principles of quantum mechanics and the theory of
special relativity, and was the first theory to account fully for special
relativity in the context of quantum mechanics. It was validated by
accounting for the fine details of the hydrogen spectrum in a completely
is a concept used in physics to explain the nature of certain fields,
including the gravitational field and a number of quantum field effects.
In more speculative theories, negative energy is involved in wormholes
which allow time travel and warp drives for faster-than-light space
Outline of Energy
are high-energy radiation, mainly originating
outside the Solar System. Upon impact with the Earth's atmosphere, cosmic
rays can produce showers of secondary particles that sometimes reach the
surface. Composed primarily of high-energy protons and atomic nuclei, they
are of mysterious origin. Data from the Fermi space telescope (2013) have
been interpreted as evidence that a significant fraction of primary cosmic
rays originate from the supernovae explosions of stars. Active galactic
nuclei probably also produce cosmic rays.
Ultra-High-Energy Cosmic Ray
is a cosmic ray particle with a
kinetic energy greater than 1×1018 eV, far beyond both the rest mass and
energies typical of other cosmic ray particles. An extreme-energy cosmic
ray (EECR) is an UHECR with energy exceeding 5×1019 eV (about 8 joule),
the so-called Greisen–Zatsepin–Kuzmin limit (GZK limit). This limit should
be the maximum energy of cosmic ray particles that have traveled long
distances (about 160 million light years), since higher-energy ray
particles would have lost energy over that distance due to scattering from
photons in the cosmic microwave background. It follows that EECR could not
be survivors from the early universe but are cosmologically "young",
emitted somewhere in the Local Supercluster by some unknown physical
process. These particles are extremely rare; between 2004 and 2007, the
initial runs of the Pierre Auger Observatory detected 27 events with
estimated arrival energies above 5.7×1019 eV, i.e., about one such event
every four weeks in the 3000 km2 area surveyed by the observatory. There
is evidence that these highest-energy cosmic rays might be iron nuclei,
rather than the protons that make up most cosmic rays.
is a unit of energy equal to approximately 160
zeptojoules (10−21 joules, symbol zJ) or 1.6×10−19 joules (symbol J). By
definition, it is the amount of energy gained (or lost) by the charge of a
single electron moving across an electric potential difference of one
volt. Thus it is 1 volt (1 joule per coulomb, 1 J/C) multiplied by the
elementary charge (e, or 1.6021766208(98)×10−19 C). Therefore, one
electronvolt is equal to 1.6021766208(98)×10−19 J. Historically, the
electronvolt was devised as a standard unit of measure through its
usefulness in electrostatic particle accelerator sciences because a
particle with charge q has an energy E = qV after passing through the
potential V; if q is quoted in integer units of the elementary charge and
the terminal bias in volts, one gets an energy in eV.
arise from a fact that each atom within a
molecule occupies a certain amount of space. If atoms are brought too
close together, there is an associated cost in energy due to overlapping
electron clouds (Pauli or Exchange interaction, or Born repulsion), and
this may affect the molecule's preferred shape (conformation) and
is a unit of length, equal to
1.616229(38)×10−35 metres. It is a base unit in the system of Planck
units, developed by physicist Max Planck. The Planck length can be defined
from three fundamental physical constants: the speed of light in a vacuum,
the Planck constant, and the gravitational constant.
Letter to the President: Physics Education
Through the Wormhole
Introduction to Atomic Structure
khan Academy Electron Configurations
(youtube channel of science and engineering)
Science Videos and Films
Institute of Physics
Physics 4 Kids
Nordic Institute for
Publications in Physics
international collaboration based at CERN, and who is working with trapped
antihydrogen atoms, the antimatter counterpart of the simplest atom,
hydrogen. By precise comparisons of hydrogen and antihydrogen, the
experiment hopes to study fundamental symmetries between matter and
Large Hadron Collider
is the world's largest and most powerful
particle collider, most complex experimental facility ever built, and the
largest single machine in the world. It was built by the European
Organization for Nuclear Research (CERN) between 1998 and 2008 in
collaboration with over 10,000 scientists and engineers from over 100
countries, as well as hundreds of universities and laboratories. It lies
in a tunnel 27 kilometres (17 mi) in circumference, as deep as 175 metres
(574 ft) beneath the France–Switzerland border near Geneva, Switzerland.
Its first research run took place from 30 March 2010 to 13 February 2013
at an initial energy of 3.5 teraelectronvolts (TeV) per beam (7 TeV
total), almost 4 times more than the previous world record for a collider,
rising to 4 TeV per beam (8 TeV total) from 2012. On 13 February 2013 the
LHC's first run officially ended, and it was shut down for planned
upgrades. 'Test' collisions restarted in the upgraded collider on 5 April
2015, reaching 6.5 TeV per beam on 20 May 2015 (13 TeV total, the current
world record). Its second research run commenced on schedule, on 3 June
2015. The aim of the LHC is to allow physicists to test the predictions of
different theories of particle physics, including measuring the properties
of the Higgs boson and searching for the large family of new particles
predicted by supersymmetric theories, as well as other unsolved questions
of physics. The collider has four crossing points, around which are
positioned seven detectors, each designed for certain kinds of research.
The LHC primarily collides proton beams, but it can also use beams of lead
nuclei. Proton–lead collisions were performed for short periods in 2013
and 2016, and lead–lead collisions took place in 2010, 2011, 2013, and
2015. The LHC's computing grid is a world record holder. Data from
collisions was produced at an unprecedented rate for the time of first
collisions, tens of petabytes per year, a major challenge at the time, to
be analysed by a grid-based computer network infrastructure connecting 140
computing centres in 35 countries – by 2012 the Worldwide LHC Computing
Grid was also the world's largest distributed computing grid, comprising
over 170 computing facilities in a worldwide network across 36 countries.
inside the Large Hadron Collider (360 video) - BBC News
a particle that follows Bose–Einstein statistics. Bosons make up one of
the two classes of particles
, the other being
fermions. The name boson was coined by Paul Dirac to commemorate the
contribution of the Indian physicist Satyendra Nath Bose in developing,
with Einstein, Bose–Einstein statistics—which theorizes the
characteristics of elementary particles. Examples of bosons include
fundamental particles such as photons, gluons, and W and Z bosons (the
four force-carrying gauge bosons of the Standard Model), the recently
discovered Higgs boson, and the hypothetical graviton of quantum gravity;
composite particles (e.g. mesons and stable nuclei of even mass number
such as deuterium (with one proton and one neutron, mass number = 2),
helium-4, or lead-208); and some quasiparticles (e.g. Cooper pairs,
plasmons, and phonons).
is an elementary particle in the Standard Model of particle
physics. It is the quantum excitation of the Higgs field, a fundamental
field of crucial importance to particle physics theory first suspected to
exist in the 1960s. Unlike other known fields such as the electromagnetic
field, it has a non-zero constant value in vacuum. The question of the
Higgs field's existence has been the last unverified part of the Standard
Model of particle physics and, according to some, "the central problem in
Higgs Boson T-Shirts
was a circular particle accelerator (now inactive,
since 2011) in the United States, at the Fermi National Accelerator
Laboratory (also known as Fermilab), just east of Batavia, Illinois, and
holds the title of the second highest energy particle collider in the
world, after the Large Hadron Collider (LHC) of the European Organization
for Nuclear Research (CERN) near Geneva, Switzerland. The Tevatron was a
synchrotron that accelerated protons and antiprotons in a 6.86 km, or 4.26
mi, ring to energies of up to 1 TeV, hence its name. The Tevatron was
completed in 1983 at a cost of $120 million and significant upgrade
investments were made in 1983–2011.
is a particular type of cyclic particle
accelerator, descended from the cyclotron, in which the accelerating
particle beam travels around a fixed closed-loop path. The magnetic field
which bends the particle beam into its closed path increases with time
during the accelerating process, being synchronized to the increasing
kinetic energy of the particles . The synchrotron is one of the first
accelerator concepts to enable the construction of large-scale facilities,
since bending, beam focusing and acceleration can be separated into
different components. The most powerful modern particle accelerators use
versions of the synchrotron design. The largest synchrotron-type
accelerator is the 27-kilometre-circumference (17 mi) Large Hadron
Collider (LHC) near Geneva, Switzerland, built in 2008 by the European
Organization for Nuclear Research (CERN).
is the act of making and
. Taking a patient look. A
remark expressing careful consideration
by observing. The act of
noticing or paying attention
of information from a primary source. In living beings,
observation employs the
. In science, observation can also involve the recording of data
via the use of instruments
term may also refer to any data
collected during the
can be qualitative, that is, only the absence or presence of
a property is noted, or quantitative if a numerical value is attached to
the observed phenomenon by counting or measuring.
active acquisition of information
from a primary source. In living beings, observation employs the
. In science,
observation can also involve the recording of data via the use of
instruments. The term may also refer to any data collected during the
. Observations can be qualitative, that is, only the
absence or presence of a property is noted, or quantitative if a numerical
value is attached to the observed phenomenon by counting or measuring.
is the act of detecting something new, or
something "old" that had been unrecognized as meaningful. With reference
to sciences and academic disciplines, discovery is the observation of new
phenomena, new actions, or new events and providing new reasoning to
explain the knowledge gathered through such observations with previously
acquired knowledge from abstract thought and everyday experiences. A
discovery may sometimes be based on earlier discoveries, collaborations,
or ideas. Some discoveries represent a radical breakthrough in knowledge
(observe, orient, decide, and act)
draws inferences from a sample to a
population where the independent variable is not under the control of the
researcher because of ethical concerns or logistical constraints. One
common observational study is about the possible effect of a treatment on
subjects, where the assignment of subjects into a treated group versus a
control group is outside the control of the investigator. This is in
contrast with experiments
, such as
randomized controlled trials
where each subject is randomly assigned to a treated group or a control
meaning on its first encounter or at first sight. The literal translation
would be "at first face" or "at first appearance".
Atomic Force Microscopy
is a very-high-resolution type of
scanning probe microscopy (SPM), with demonstrated resolution on the order
of fractions of a nanometer, more than 1000 times better than the optical
diffraction limit. Scanning-force Microscopy (SFM).
identify atoms by detecting the energy of
is an early experimental electrical discharge
tube, with vacuum, used to discover the properties of cathode rays.
is a microscope that uses a beam of
as a source of
Scanning Probe Microscopy
is a branch of microscopy that
forms images of surfaces using a physical probe that scans the specimen.
Scanning Tunneling Microscope
is an instrument for imaging
surfaces at the atomic level.
Light Sheet Fluorescence Microscopy
is a fluorescence
microscopy technique with an intermediate optical resolution, but good
optical sectioning capabilities and high speed.
is an analytical technique that ionizes chemical species and sorts the
ions based on their mass-to-charge ratio. In simpler terms, a mass
spectrum measures the masses within a sample. Mass spectrometry is used in
many different fields and is applied to pure samples as well as complex
is the breakdown of proteins into smaller polypeptides or amino acids.
Nuclear magnetic resonance spectroscopy of proteins (NMR)
is a field of structural biology in which NMR spectroscopy is used to
obtain information about the structure and dynamics of proteins, and also
nucleic acids, and their complexes.
Electron paramagnetic resonance (EPR)
is a method for studying materials with unpaired electrons.
is a form of transmission electron microscopy (TEM) where the sample is
studied at cryogenic temperatures (generally liquid-nitrogen
Multiangle light scattering
describes a technique for measuring the light scattered by a sample into a
plurality of angles.
Small angle scattering
is a small-angle scattering method for structure analysis of biological
Ultrafast laser spectroscopy
is a spectroscopic technique that uses ultrashort pulse lasers for the
study of dynamics on extremely short time scales (attoseconds to
is an analytical technique that probes molecular layers adsorbed to the
surface of a waveguide using the evanescent wave of a laser beam. It is
used to measure the conformational change in proteins, or other
biomolecules, as they function (referred to as the conformation activity
is dichroism involving circularly polarized light,
i.e., the differential absorption of left- and right-handed light.
Left-hand circular (LHC) and right-hand circular (RHC) polarized light
represent two possible spin angular momentum states for a photon, and so
circular dichroism is also referred to as dichroism for spin angular
is a family of techniques in which waves, usually electromagnetic waves,
are superimposed causing the phenomenon of interference in order to
extract information. Interferometry is an important investigative
technique in the fields of astronomy, fiber optics, engineering metrology,
optical metrology, oceanography, seismology, spectroscopy (and its
applications to chemistry), quantum mechanics, nuclear and particle
physics, plasma physics, remote sensing, biomolecular interactions,
surface profiling, microfluidics, mechanical stress/strain measurement,
velocimetry, and optometry.
is a demonstration that light and
matter can display characteristics of both classically defined waves and
particles; moreover, it displays the fundamentally probabilistic nature of
Wave Particle Duality
is the concept that every elementary
particle or quantic entity may be partly described in terms not only of
particles, but also of waves. It expresses the inability of the classical
concepts "particle" or "wave" to fully describe the behavior of
"I like it when a surfer tells me
that "Life is a Wave
!" I like to reply and say that "Life is also a
particle and not just a wave", so go for it dude, enjoy the ride."
Wave Function Collapse
is said to occur when a wave
function—initially in a superposition of several eigenstates—appears to
reduce to a single eigenstate (by "observation"). It is the essence of
measurement in quantum mechanics and connects the wave function with
classical observables like position and momentum.
was the first known example of a
hidden variable theory
, where the state of a physical system, as
formulated by quantum mechanics, does not give a complete description for
the system; i.e., that quantum mechanics is ultimately incomplete, and
that a complete theory would provide descriptive categories to account for
all observable behavior and thus avoid any indeterminism.
are nonlinear standing waves that appear on
liquids enclosed by a vibrating receptacle. When the vibration frequency
exceeds a critical value, the flat hydrostatic surface becomes unstable.
This is known as the Faraday instability.
is a parameter applying to waves that
specifies the geometrical orientation of the oscillation. Electromagnetic
waves such as light exhibit multiple polarizations, as do gravitational
waves and sound waves in solids. On the other hand, sound waves in a
gas or liquid only oscillate in the wave's direction of propagation, and
the oscillation of ocean waves is always in the vertical direction. In
these cases one doesn't normally speak of "polarization" since the
oscillation's direction is not in question.
PhysClips Waves and Sound
Order and Disorder (physics)
designates the presence or absence of
or correlation in a
Quantum Super Position
is a fundamental principle of quantum
mechanics. It states that, much like waves in classical physics, any two
(or more) quantum states can be added together ("superposed") and the
result will be another valid quantum state; and conversely, that every
quantum state can be represented as a sum of two or more other distinct
states that, for all linear systems, the net
response at a given place and time caused by two or more stimuli is the
sum of the responses that would have been caused by each stimulus
individually. So that if input A produces response X and input B produces
response Y then input (A + B) produces response (X + Y).
Quantum Zeno Effect
is a situation in which an unstable
particle, if observed continuously, will never decay. One can "freeze" the
evolution of the system by measuring it frequently enough in its known
is a physical phenomenon that occurs
when pairs or groups of particles are generated or interact in ways such
that the quantum state of each particle cannot be described independently
of the others, even when the particles are separated by a large
distance—instead, a quantum state must be described for the system as a
is the lowest possible energy that a
quantum mechanical system may have, i.e. it is the energy of the system's
ground state. Zero-point energy can have several different types of
context, e.g. it may be the energy associated with the ground state of an
atom, a subatomic particle or even the quantum vacuum itself.
Everywhere and Nowhere at Once
also known as Heisenberg's uncertainty
principle, is any of a variety of mathematical inequalities asserting a
fundamental limit to the precision with which certain pairs of physical
properties of a particle, known as complementary variables, such as
position x and momentum p, can be known.
refers to changes that the act of
observation will make on a phenomenon being observed. This is often the
result of instruments that, by necessity, alter the state of what they
measure in some manner. A commonplace example is checking the pressure in
an automobile tire; this is difficult to do without letting out some of
the air, thus changing the pressure. Furthermore, it is not possible to
see any object without light hitting the object, and causing it to emit
light; while this may seem negligible, the object still experiences a
change. This effect can be observed in many domains of physics and can
often be reduced to insignificance by using better instruments or
observation techniques. In quantum mechanics, there is a common
misconception that it is the mind of a conscious observer that causes the
observer effect in quantum processes. It is rooted in a misunderstanding
of the quantum wave function ψ and the quantum measurement process.
is a software bug that seems to disappear or alter
its behavior when one attempts to study it.
is unintended alteration in system
behavior caused by measuring that system. In code profiling and
performance measurements, the delays introduced by insertion/removal of
code instrumentation may result in a non-functioning application, or
Wheeler's Delayed Choice Experiment
is actually several
thought experiments in quantum physics, proposed by John Archibald
Wheeler, with the most prominent among them appearing in 1978 and 1984.
These experiments are attempts to decide whether light somehow "senses"
the experimental apparatus in the double-slit experiment it will travel
through and adjusts its behavior to fit by assuming the appropriate
determinate state for it, or whether light remains in an indeterminate
state, neither wave nor particle.
takes the psi and psi* wave
functions of the standard quantum formalism to be retarded (forward in
time) and advanced (backward in time) waves that form a quantum
interaction as a Wheeler–Feynman handshake or transaction.
De Broglie-Bohm Theory
is an interpretation of quantum
theory. In addition to a wavefunction on the space of all possible
configurations, it also postulates an actual configuration that exists
even when unobserved.
is the change in frequency or
wavelength of a wave (or other periodic event) for an observer moving
relative to its source. It is named after the Austrian physicist Christian
Doppler, who proposed it in 1842 in Prague. It is commonly heard when a
vehicle sounding a siren or horn approaches, passes, and recedes from an
observer. Compared to the emitted frequency, the received frequency is
higher during the approach, identical at the instant of passing by, and
lower during the recession.
pilot-wave dynamics of walking droplets
is a thought experiment, sometimes
described as a paradox, devised by Austrian physicist Erwin Schrödinger in
1935. It illustrates what he saw as the problem of the Copenhagen
interpretation of quantum mechanics applied to everyday objects. The
scenario presents a cat that may be simultaneously both alive and dead, a
state known as a quantum superposition, as a result of being linked to a
random subatomic event that may or may not occur. The thought experiment
is also often featured in theoretical discussions of the interpretations
of quantum mechanics. Schrödinger coined the term Verschränkung
(entanglement) in the course of developing the thought experiment.
is the phenomenon of a decrease in length of an
object as measured by an observer who is traveling at any non-zero
velocity relative to the object.
was an American scientist who has been described
as one of the most significant theoretical physicists of the 20th century
and who contributed unorthodox ideas to quantum theory, neuropsychology
and the philosophy of mind.
was an American theoretical physicist known
for his work in the path integral formulation of quantum mechanics, the
theory of quantum electrodynamics, and the physics of the superfluidity of
supercooled liquid helium, as well as in particle physics for which he
proposed the parton model. For his contributions to the development of
quantum electrodynamics, Feynman, jointly with Julian Schwinger and
Sin'ichirō Tomonaga, received the Nobel Prize in Physics in 1965.
refers to the problem of ascertaining
which parts of one image correspond to which parts of another image, where
differences are due to movement of the camera, the elapse of time, and/or
movement of objects in the photos.
two wave sources are perfectly coherent if they
have a constant phase difference and the same frequency. It is an ideal
property of waves that enables stationary (i.e. temporally and spatially
constant) interference. It contains several distinct concepts, which are
limiting cases that never quite occur in reality but allow an
understanding of the physics of waves, and has become a very important
concept in quantum physics. More generally, coherence describes all
properties of the correlation between physical quantities of a single
wave, or between several waves or wave packets.
Widely used engineering technique has unintended consequences
Focused Ion Beam
can in fact dramatically alter the material’s
structural identity. A FIB setup is a scientific instrument that resembles
scanning electron microscope
(SEM). However, while the SEM uses a
to image the sample in the chamber, a FIB setup uses a
instead. FIB can also be incorporated
in a system with both electron
and ion beam
columns, allowing the same feature to be investigated using either of the
beams. FIB should not be confused with using a beam of focused ions for
(such as in
proton beam writing
). These are generally quite different systems
where the material is modified by other mechanisms.
Humans can only see a small percentage of the entire
with our eyes
, but with technology we can see
almost all the wavelengths.
is the portion of the electromagnetic spectrum that is
visible to the human eye.
is the collective term for all known
frequencies and their linked wavelengths of the known
(electromagnetic radiation). The
"electromagnetic spectrum" of an object has a different meaning, and is
instead the characteristic distribution of electromagnetic radiation
emitted or absorbed by that particular object. The electromagnetic
spectrum extends from below the low frequencies used for modern radio
communication to gamma radiation at the short-wavelength (high-frequency)
end, thereby covering wavelengths from thousands of kilometers down to a
fraction of the size of an atom. Visible light lies toward the shorter
end, with wavelengths from 400 to 700 nanometres
. The limit for long
wavelengths is the size of the universe itself, while it is thought that
the short wavelength limit is in the vicinity of the Planck length. Until
the middle of the 20th century it was believed by most physicists that
this spectrum was infinite and continuous. Nearly all types of
electromagnetic radiation can be used for spectroscopy, to study and
characterize matter. Other technological uses are described under
is the portion of the electromagnetic spectrum that
is visible to the human eye
. Electromagnetic radiation in this range of
wavelengths is called visible light or simply light
. A typical human eye
will respond to wavelengths from about 390 to 700 nm. In terms of
frequency, this corresponds to a band in the vicinity of 430–770 THz. The
spectrum does not, however, contain all the colors that the human eyes and
brain can distinguish. Unsaturated colors
such as pink, or purple
variations such as magenta, are absent, for example, because they can be
made only by a mix of multiple wavelengths. Colors containing only one
wavelength are also called pure colors or spectral colors. Visible
wavelengths pass through the "optical window", the region of the
electromagnetic spectrum that allows wavelengths to pass largely unattenuated through the Earth's atmosphere. An example of this phenomenon
is that clean air scatters blue light more than red wavelengths, and so
the midday sky appears blue. The optical window is also referred to as the
"visible window" because it overlaps the human visible response spectrum.
The near infrared (NIR) window lies just out of the human vision, as well
as the Medium Wavelength IR (MWIR) window, and the Long Wavelength or Far
Infrared (LWIR or FIR) window, although other animals may experience them. Light
is the optical portion of the electromagnetic spectrum
that passes through the atmosphere all the way to the ground. Most EM
wavelengths are blocked by the atmosphere, so this is like a window that
lets through only a narrow selection of what is out there, though the Sun
is particularly active in the passed wavelengths. It is called "optical"
because the wavelengths we can see are all in this range. The window runs
from around 300 nanometers (ultraviolet-B) at the short end up into the
range the eye can use, roughly 400-700 nm and continues up through the
visual infrared to around 1100 nm, which is in the near-infrared range.
There are also infrared and "radio windows" that transmit some infrared
and radio waves. The radio window runs from about one centimeter to about
eleven-meter waves. In medical physics, the optical window is the portion
of the visible and infrared spectrum where living tissue absorbs
relatively little light. This window runs approximately from 650 nm to
1200 nm. At shorter wavelengths light is strongly absorbed by hemoglobin
in blood, while at longer wavelengths water strongly absorbs infrared
light. In optics, it means a (usually at least mechanically flat,
sometimes optically flat, depending on resolution requirements) piece of
transparent (for a wavelength range of interest, not necessarily for
visible light) optical material that allows light into an optical
instrument. A window is usually parallel and is likely to be anti
reflection coated, at least if it is designed for visible light. An
optical window may be built into a piece of equipment (such as a vacuum
chamber) to allow optical instruments to view inside that equipment.
is the condition of possessing three independent channels
for conveying color information, derived from the three different cone
types. Organisms with trichromacy are called trichromats.
is a condition that is not limited to a specific
set of values but can vary, without steps, across a continuum. The word
was first used scientifically in optics to describe the rainbow of colors
in visible light after passing through a prism. As scientific
understanding of light advanced, it came to apply to the entire
describes the distribution of power into frequency
components composing that signal. According to Fourier analysis any
physical signal can be decomposed into a number of discrete frequencies,
or a spectrum of frequencies over a continuous range. The statistical
average of a certain signal or sort of signal (including noise) as
analyzed in terms of its frequency content, is called its spectrum.
measures the magnitude of an input signal versus
frequency within the full frequency range of the instrument. The primary
use is to measure the power of the spectrum of known and unknown signals.
The input signal that a spectrum analyzer measures is electrical; however,
spectral compositions of other signals, such as acoustic pressure waves
and optical light waves, can be considered through the use of an
appropriate transducer. Optical spectrum analyzers also exist, which use
direct optical techniques such as a monochromator to make measurements.
is an apparatus used to split light into an
array of separate colors
, called a spectrum. Generally, a spectrum is a
graph that shows intensity as a function of wavelength, of frequency, of
energy, of momentum, or of mass.
is an electromagnetic radiation
from 10 nm (30 PHz) to 400 nm (750 THz), shorter than that of
visible light but longer than X-rays. UV radiation
constitutes about 10%
of the total light output of the Sun, and is thus present in sunlight. It
is also produced by electric arcs and specialized lights such as
mercury-vapor lamps, tanning lamps, and black lights. Although it is not
considered an ionizing radiation because its photons lack the energy to
ionize atoms, long-wavelength ultraviolet radiation can cause chemical
reactions and causes many substances to glow or
biological effects of UV are greater than simple
, and many
practical applications of UV radiation derive from its interactions with
organic molecules. UV Index
Can You See Me?
FLIR T1K Thermal Imaging Camera
examples of infrared imaging science. Thermographic cameras usually detect
radiation in the long-infrared range of the electromagnetic spectrum
(roughly 9,000–14,000 nanometers or 9–14 µm) and produce images of that
radiation, called thermograms. Since infrared radiation is emitted by all
objects with a temperature above absolute zero according to the black body
radiation law, thermography makes it possible to see one's environment
with or without visible illumination. The amount of radiation emitted by
an object increases with temperature; therefore, thermography allows one
to see variations in temperature. When viewed through a thermal imaging
camera, warm objects stand out well against cooler backgrounds; humans and
other warm-blooded animals become easily visible against the environment,
day or night. As a result, thermography is particularly useful to the
military and other users of surveillance cameras.
electromagnetic radiation (EMR) with longer wavelengths than those of
visible light, and is therefore invisible, although it is sometimes
loosely called infrared light. It extends from the nominal red edge of the
visible spectrum at 700 nanometers (frequency 430 THz), to 1000000 nm (300
GHz) (although people can see infrared up to at least 1050 nm in
experiments. Most of the thermal radiation emitted by objects near room
temperature is infrared. Like all EMR, IR carries radiant energy, and
behaves both like a wave and like its quantum particle, the
Infrared Astronomical Satellite
GLEAM Data Sphere
Red indicates the lowest frequencies, green the middle
frequencies and blue the highest frequencies. (video)
you explore our Galaxy (the Milky Way) and the distant Universe in a range
of wavelengths from gamma-rays to the longest radio waves.
in this range of wavelengths is called
or simply light. A typical
human eye will respond to wavelengths from about 390 to 700 nm. In
terms of frequency, this corresponds to a band in the vicinity of 430–770
Wave of the future: Terahertz chips a new way of seeing through matter
1 E-7 m
Higher Frequency as things get Smaller
Graph below is Reversed
Ultrathin, flat lens resolves chirality and color Light can also be chiral
In chiral light, the direction of oscillation of the
wave. Multispectral chiral lens.Computers act like human brains
because human brains made computers.
not mean that
machines can be humans
No one created math, math was discovered because
already existed in nature
. And just because math exists in
nature does not mean that all life is a calculation.
because humans understand how
and see the similarities in life.
This does not mean that
life is a
. But what it does mean is that we are getting
to fully understanding how our universe works, and that we have
then we ever dreamed
about having. When people ask the wrong questions they can
easily make inaccurate assumptions.
Science: Episode One - The Simulation Hypothesis
Does matter create mind or does mind create matter
? Both. Matter creates the mind and the mind
Mind & Matter
is the position that mental phenomena are, in some
respects, non-physical, or that the mind and body are not identical. Thus,
it encompasses a set of views about the relationship between mind and
matter, and between subject and object, and is contrasted with other
positions, such as physicalism and enactivism, in the mind–body problem.
is a mathematical inequality
fulfilled by all macrorealistic physical theories. Here, macrorealism
(macroscopic realism) is a classical worldview defined by the conjunction
of two postulates: Macrorealism per se: "A macroscopic object, which has
available to it two or more macroscopically distinct states, is at any
given time in a definite one of those states." Noninvasive measurability:
"It is possible in principle to determine which of these states the system
is in without any effect on the state itself, or on the subsequent system
is having material
or physical form or substance. Affecting or characteristic of the body as
opposed to the mind or spirit.
Mind over Matter
...as a Matter of Fact
drives the Mass