- Laws of science
The laws of science are various established
scientific laws, or physical laws as they are sometimes called, that are considered universal and invariable facts of the physical world. Laws of science may, however, be disproved if new facts or evidence contradicts them. A "law" differs from hypotheses, theories, postulates, principles, etc., in that a law is an analytic statement, usually with an empirically determined constant. A theory may contain a set of laws, or a theory may be implied from an empirically determined law.
Conservative estimates indicate that there are 18 basic physical laws in the universe: [cite book | last = Powell | first = Michael | title = Stuff You Should Have Learned at School | publisher = Barnes & Noble Books | year = 2004 | id = ISBN 0-7607-6279-1] Fluid mechanics
Archimedes’ principleForce, mass, and inertia
*Kepler’s three laws of planetary motion
*Newton’s three laws of motion
law of universal gravitationHeat, energy, and temperature
*Newton’s law of cooling
conservation of energy
*Joule’s first and second law
laws of thermodynamicsQuantum mechanics
uncertainty principleOthers, such as Roger Penrosewith his 2004 book The Road to Reality– a complete guide to the laws of the universe, argues that there are a large number of established laws of science. Some laws, such as Descartes’ "first law of nature", have become obsolete. A rough outline of the basic laws in science is as follows:
Most significant laws in science are
These fundamental laws follow from homogeneity of
space, timeand phase (see Emmy Noether theorem).
Other less significant (non fundamental) laws are the mathematical consequences of the above conservation laws for derivative physical quantities (mathematically defined as
force, pressure, temperature, density, force fields, etc):
Boyle's Law( pressureand volumeof ideal gas)
* Charles & Gay-Lussac (gases expand equally with the same change of
Ideal Gas Law""
Energyof photons - Energy equals Planck's constantmultiplied by the frequencyof the light. :*: : Special Relativity::* Constancy of the speed of light::* Lorentz transformations- Transformations of Cartesian coordinates between relatively moving reference frames.::*: ::*: ::*: ::*: ::*Mass-energy equivalence::*: ( Energy= mass× speed of light2): General Relativity::* Energy-momentum (including mass via "E=mc"2) curves spacetime.::*: This is described by the Einstein field equations:::*: ::*: is the Ricci tensor, is the Ricci scalar, is the metric tensor, is the stress-energy tensor, and the constant is given in terms of ( pi), (the speed of light) and (the gravitational constant).::*: E=mc2 where m=m0/sqrt(1-(v2/c2)
Newton's laws of motion- Replaced with relativity:*: *1. Law of Inertia:*: *2. Although it implies , that is not necessarily true.:*: *3. Force of a on b equals the negative force of b on a, or for every action there is an equal and opposite reaction.:* Law of heat conduction:* General law of gravitation - Gravitational forcebetween two objects equals the gravitational constanttimes the product of the masses divided by the distancebetween them squared.:*::*:This law is really just the low limit solution of Einstein's field equationsand is not accurate with modern high precision gravitational measurements.
Chemical laws are those
laws of naturerelevant to chemistry. The most fundamental concept in chemistry is the law of conservation of mass, which states that there is no detectable change in the quantity of matter during an ordinary chemical reaction. Modern physics shows that it is actually energythat is conserved, and that energy and mass are related; a concept which becomes important in nuclear chemistry. Conservation of energyleads to the important concepts of equilibrium, thermodynamics, and kinetics.
Additional laws of chemistry elaborate on the law of conservation of mass.
Joseph Proust's law of definite compositionsays that pure chemicals are composed of elements in a definite formulation; we now know that the structural arrangement of these elements is also important.
law of multiple proportionssays that these chemicals will present themselves in proportions that are small whole numbers (i.e. 1:2 O:H in water); although in many systems (notably biomacromolecules and minerals) the ratios tend to require large numbers, and are frequently represented as a fraction. Such compounds are known as non-stoichiometric compounds
More modern laws of chemistry define the relationship between energy and transformations.
* In equilibrium, molecules exist in mixture defined by the transformations possible on the timescale of the equilibrium, and are in a ratio defined by the intrinsic energy of the molecules—the lower the intrinsic energy, the more abundant the molecule.
* Transforming one structure to another requires the input of energy to cross an energy barrier; this can come from the intrinsic energy of the molecules themselves, or from an external source which will generally accelerate transformations. The higher the energy barrier, the slower the transformation occurs.
* There is a hypothetical intermediate, or "transition structure", that corresponds to the structure at the top of the energy barrier. The
Hammond-Leffler Postulatestates that this structure looks most similar to the product or starting material which has intrinsic energy closest to that of the energy barrier. Stabilizing this hypothetical intermediate through chemical interaction is one way to achieve catalysis.
* All chemical processes are reversible (law of
microscopic reversibility) although some processes have such an energy bias, they are essentially irreversible.
Coulomb's law- Forcebetween any two charges is equal to the absolute valueof the multiple of the charges divided by 4 pitimes the vacuum permittivity times the distancesquared between the two charges.:
Kirchhoff's circuit laws(current and voltagelaws)
Kirchhoff's law of thermal radiation
Maxwell's equations(electric and magnetic fields):
Thermodynamics:* Zeroth law of thermodynamics:*::* First law of thermodynamics:*::* Second law of thermodynamics:*::* Third law of thermodynamics:*: :* Onsager reciprocal relations- sometimes called the "Fourth Law of Thermodynamics":*: ;:*: .
Quantum Mechanics:* Heisenberg Uncertainty Principle- Uncertaintyin positionmultiplied by uncertainty in momentumis equal to or greater than Dirac's constantdivided by 2.:*: :* De Broglie hypothesis- Laid the foundations of particle-wave dualityand was the key idea in the Schrödinger equation.:*::* Schrödinger equation- Describes the time dependence of a quantum mechanical system.:*: :*: The Hamiltonian "H"("t") is a self-adjoint operatoracting on the state space, is the instantaneous state vectorat time "t", "i" is the unit imaginary number, is Planck's constantdivided by 2π
It is thought that the successful integration of
Einstein's field equationswith the uncertainty principleand Schrödinger equation, something no one has achieved so far with a testable theory, will lead to a theory of quantum gravity, the most basic physical law sought after today.
Navier-Stokes equationsof fluid dynamics:
Poiseuille's law(voluminal laminar stationaryflow of incompressible uniform viscous liquid through a cylindrical tube with the constant circular cross-section):Radiation laws:* Planck's law of black body radiation( spectral densityin a radiationof a black-body):* Wien's law(wavelength of the peak of the emission of a black body) :"λ0T" = "kw":* Stefan-Boltzmann law(total radiation from a black body):*:
Laws of Kepler( planetary motion)
Dulong-Petit law( specific heat capacityat constant volume)
Buys-Ballot's law(wind travels counterclockwise around low pressure systems in the Northern Hemisphere)
Physical law- includes discussion of what constitutes a law
Scientific laws named after people
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