उन भौतिक नियमों को विज्ञान के नियम कहा जाता है जो सार्वत्रिक (universal) समझे जाते हैं तथा जो भौतिक जगत के अपरिवर्तनशील तथ्य हैं।
[संदिग्ध – वार्ता] किन्तु फिर भी, यदि कोई नया तथ्य या साक्ष्य मिलता है जो इस नियम के विरुद्ध हो तो विज्ञान के नियम असत्य सिद्ध हो सकते हैं। "नियम", परिकल्पना (hypotheses), सिद्धान्त (theories), अभिगृहीत (postulates), प्रिंसिपल (principle) आदि से इस मामले में अलग है कि नियम विश्लेषणात्मक कथन (analytic statement) होता है जिसमें प्राय: प्रयोग द्वारा कोई नियतांक प्राप्त किया गया होता है। किसी सिद्धान्त में कई नियम हो सकते हैं या वह सिद्धान्त किसी नियम से इंगित होता हो सकता है।
एक मोटे अनुमान के अनुसार ब्रह्माण्ड में कोई १८ मूल भौतिक नियम होंगे।
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तरल यांत्रिकी
बल, द्रव्यमान एवं त्वरण
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उष्मा, उर्जा एवं ताप
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क्वाण्टम यांत्रिकी
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संरक्षन के नियम विज्ञान में सर्वाधिक महत्त्व रखते हैं।
- [[द्रव्य की अविनाशिता का नियम
द्रव्यमान संरक्षण का नियम(Conservation of mass)
ये मूल नियम स्पेस, समय एवं कला (phase) की समांगता (homogeneity) के परिणाम हैं। एमी नीदर का प्रमेय (Emmy Noether theorem) देखिये।
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 (pressure and volume of ideal gas)
- Charles & Gay-Lussac (gases expand equally with the same change of temperature)
- Ideal Gas Law
मुख्य लेख: Chemical law
Chemical laws are those laws of nature relevant 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 energy that is conserved, and that energy and mass are related; a concept which becomes important in nuclear chemistry. Conservation of energy leads 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 composition says that pure chemicals are composed of elements in a definite formulation; we now know that the structural arrangement of these elements is also important.
Dalton's law of multiple proportions says 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.
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 Postulate states 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 - Force between any two charges is equal to the product of the charges divided by 4 pi times the vacuum permittivity times the distance squared between the two charges.
- Kirchhoff's circuit laws (current and voltage laws)
- Kirchhoff's law of thermal radiation
- Maxwell's equations (electric and magnetic fields):
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Partial Differential form |
Gauss's law : |
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Gauss's law for magnetism: |
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Faraday's law of induction: |
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Ampère's law + Maxwell's extension: |
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- Navier-Stokes equations of fluid dynamics
- Poiseuille's law (voluminal laminar stationary flow of incompressible uniform viscous liquid through a cylindrical tube with the constant circular cross-section)
- Planck's law of black body radiation (spectral density in a radiation of 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)
- Beer-Lambert (light absorption)
- Dulong-Petit law (specific heat capacity at constant volume)
- Buys-Ballot's law (wind travels counterclockwise around low pressure systems in the Northern Hemisphere)
- भौतिक नियम (Physical law) - यहाँ इस पर भी चर्चा है कि 'नियम' किसे कहा जाय।
- व्यक्तियों के नाम से प्रसिद्ध वैज्ञानिक नियम