Physics

Physical laws, constants, and phenomena — from quantum mechanics to thermodynamics — explained in plain language.

100 concepts. Regenerated daily.

Start swiping →

What Bose-Einstein condensation demonstrates — macroscopic quantum coherence at ultralow temperatures

Bose-Einstein condensation shows macroscopic quantum coherence at temperatures near absolute zero

What the Standard Model's particle content is — 6 quarks, 6 leptons, 4 gauge bosons, 1 Higgs

Standard Model: 24 fundamental particles (6 quarks, 6 leptons, 4 gauge bosons, 1 Higgs)

What the Aspect experiments confirmed — Bell inequality violations prove quantum nonlocality is real

Aspect experiments demonstrated quantum entanglement's nonlocality, violating Bell's inequalities

What the Kerr solution adds — spacetime around a rotating black hole, including frame-dragging

Kerr solution describes rotating black holes' spacetime, featuring frame-dragging effects

How Eddington's 1919 eclipse observation confirmed general relativity — starlight bent by the Sun

Eddington's eclipse observation showed starlight bending due to the Sun's gravity, confirming general relativity

What type Ia supernovae revealed in 1998 — the expansion of the universe is accelerating, implying dark energy

1998 discovery: Type Ia supernovae showed universe's accelerating expansion, hinting at dark energy

What the Penrose-Hawking singularity theorems prove — singularities are inevitable in general relativity under certain conditions

Theorems assert black holes and singularities arise from gravitational collapse in spacetime

What the Goldstone theorem says — every spontaneously broken continuous symmetry produces a massless boson

Goldstone theorem: Spontaneously broken continuous symmetries yield massless Goldstone bosons

What the Ising model describes — phase transitions in ferromagnets using interacting spins on a lattice

The Ising model explains ferromagnetic phase transitions via spin interactions on a lattice

What Bell's theorem proved — no local hidden variable theory can reproduce all predictions of quantum mechanics

Bell's theorem disproved local hidden variable theories' ability to match quantum mechanics' predictions

Why Einstein's photoelectric explanation used Planck's E=hf to predict that higher frequency light ejects faster electrons

Planck's equation E=hf quantifies light energy, explaining higher frequency photons eject electrons more rapidly

What gauge symmetry is — local phase transformations that leave physics invariant, the basis of all fundamental forces

Gauge symmetry: Local phase transformations preserving physics, underlying fundamental forces

What the equivalence principle says — being in a gravitational field is locally indistinguishable from acceleration

Equivalence Principle: Gravity mimics acceleration, indistinguishable locally

What the information paradox asks — does information falling into a black hole disappear, violating quantum mechanics

The information paradox questions: Does information vanish in black holes, contradicting quantum theory?

What Feynman diagrams represent — visual shorthand for terms in perturbative quantum field theory calculations

Feynman diagrams depict interaction processes in quantum field theory perturbation expansions

What Hawking radiation implies — black holes have a temperature and slowly evaporate over time

Hawking radiation suggests black holes emit thermal radiation, gradually diminishing

What the hierarchy problem asks — why is gravity so much weaker than the other three forces

The hierarchy problem questions the vast difference in strength between gravity and other fundamental forces

What Einstein's 1905 photoelectric effect paper showed — light comes in discrete quanta, not continuous waves

Einstein's 1905 paper demonstrated light as quantized energy packets, not continuous waves

What the Higgs field does — permeates all space, gives mass to fundamental particles through coupling

The Higgs field permeates space, endowing particles with mass via interaction

What string theory proposes — fundamental objects are 1D strings vibrating in 10 or 11 dimensions

String theory posits fundamental objects as 1D strings in 10 or 11 dimensions

What quantum entanglement swapping does — entangles particles that have never directly interacted

Quantum entanglement swapping enables non-interacting particles to become entangled through a third-party interaction

How the Higgs mechanism works — spontaneous breaking of electroweak symmetry gives W and Z bosons their mass

Higgs field's non-zero vacuum expectation value breaks symmetry, endowing W and Z bosons with mass

What the Stern-Gerlach experiment showed — angular momentum is quantized, not continuous

The Stern-Gerlach experiment demonstrated that electron spin has quantized angular momentum

What the electroweak unification achieved — Glashow, Salam, and Weinberg showed EM and weak force are one

Unified electroweak theory: EM and weak force as one interaction

What the measurement problem asks — why does a quantum superposition collapse to a definite state upon observation

Quantum measurement problem: Superposition collapses due to observer interaction

What the arrow of time problem asks — why does time have a direction when fundamental laws are time-reversible

The arrow of time problem questions why entropy increases in one direction despite time-reversible laws

What the Copenhagen interpretation says — the wavefunction collapse is fundamental, observation creates reality

Copenhagen interpretation: Observing a system collapses its wavefunction, shaping reality

What the Casimir effect demonstrates — quantum vacuum fluctuations create measurable force between conducting plates

Casimir effect: Quantum fluctuations induce attractive force between parallel plates

What the path integral formulation does — Feynman showed a particle takes all possible paths simultaneously

Path integral formulation: Particle simultaneously explores all paths, summing probabilities

Why special relativity doesn't need the luminiferous aether — the Michelson-Morley null result becomes expected

Special relativity's framework negates aether's need, as light's speed is invariant, aligning with Michelson-Morley's findings

What the quantum Hall effect reveals — Hall conductance is quantized in units of e²/h

Quantum Hall effect shows quantized Hall conductance as e²/h

What the cosmological constant problem is — quantum field theory predicts vacuum energy 10^120 times too large

Quantum field theory overestimates vacuum energy by 10^120 times, causing the cosmological constant problem

What the Bose-Einstein condensate is — at near absolute zero, bosons collapse into the same quantum state

Bose-Einstein condensate: Bosons share quantum state near absolute zero

What CPT symmetry is — the combination of charge, parity, and time reversal is always conserved

CP-symmetry implies charge, parity, and time reversal conservation

What the Dirac equation predicted — relativistic quantum mechanics requires antimatter to exist

Dirac equation predicted the existence of antimatter in relativistic quantum mechanics

What dark matter candidates include — WIMPs, axions, sterile neutrinos, primordial black holes

Dark matter candidates: WIMPs, axions, sterile neutrinos, primordial black holes

What QCD (quantum chromodynamics) describes — the strong force between quarks mediated by gluons

QCD describes the strong force interactions between quarks via gluon exchange

What the Einstein field equations relate — the curvature of spacetime (Gμν) to the energy-momentum tensor (Tμν)

Einstein's field equations: Gμν = 8πTμν, relating spacetime curvature to energy-momentum

Why nothing with mass can reach the speed of light — the Lorentz factor γ diverges as v approaches c

As velocity v approaches c, Lorentz factor γ increases, preventing massive objects from reaching light speed

What spin is in quantum mechanics — an intrinsic angular momentum that has no classical analogue

Quantum spin is an intrinsic angular momentum without classical counterpart

What the Pauli exclusion principle forbids — two identical fermions from occupying the same quantum state

Pauli exclusion principle prohibits two identical fermions from sharing the same quantum state simultaneously

What supersymmetry (SUSY) predicts — every fermion has a bosonic partner and vice versa, none found yet

Supersymmetry predicts a partner particle for every known particle, unobserved so far

What Fermi-Dirac statistics describe — the distribution of fermions, which obey the exclusion principle

Fermi-Dirac statistics describe the distribution of particles like electrons, obeying the Pauli exclusion principle

What the Schwarzschild solution describes — spacetime geometry around a non-rotating spherical mass

The Schwarzschild solution describes the spacetime geometry around a non-rotating spherical mass

What primordial nucleosynthesis produced — hydrogen, helium, and traces of lithium in the first three minutes

Primordial nucleosynthesis produced hydrogen, helium, and traces of lithium in the universe's first three minutes

What baryon acoustic oscillations are — sound waves frozen in the early universe that set a standard ruler

Baryon acoustic oscillations: Early universe's sound waves, cosmic standard ruler

What Landauer's principle resolves — erasing one bit of information dissipates at least kT ln 2 of energy

Landauer's principle states energy dissipation during bit erasure is kT ln(2)

What Anderson localization is — disorder can cause waves to become trapped in a random medium

Anderson localization: Disorder traps waves in a medium due to interference

What spontaneous symmetry breaking does — the vacuum state breaks a symmetry that the laws possess

Vacuum state in quantum field theory breaks global U(1) gauge symmetry

What the spin-statistics theorem connects — integer spin particles are bosons, half-integer spin are fermions

Spin-statistics theorem: Integer spin = bosons, half-integer spin = fermions

What topological insulators are — materials that conduct on the surface but insulate in the bulk

Topological insulators: Bulk insulators, surface conductors due to non-trivial topological order

What 'Does the inertia of a body depend upon its energy content?' concluded — mass and energy are interchangeable

Inertia depends on mass, not energy content; E=mc^2 relates mass and energy

What the Boltzmann distribution describes — probability of a state with energy E is proportional to e^(-E/kT)

Boltzmann distribution: Probability of state E ∝ e^(-E/kT)

Why Einstein needed Riemannian geometry — curved spacetime requires non-Euclidean mathematics

Riemannian geometry underpins general relativity, describing curved spacetime

What the EPR paradox challenged — Einstein argued entanglement implied either hidden variables or nonlocality

EPR paradox questioned quantum mechanics' lack of locality and determinism

What Boltzmann's entropy formula states — S = k ln Ω, connecting microscopic states to macroscopic entropy

Boltzmann's formula relates entropy (S) to the natural logarithm of the number of microstates (Ω), with k as Boltzmann's constant

What the fractional quantum Hall effect shows — emergent particles with fractional charge

Fractional quantum Hall effect demonstrates emergent particles with fractional electric charge

What the strong CP problem is — why does QCD not violate CP symmetry when it has no reason not to

The strong CP problem questions why CP violation isn't observed in Quantum Chromodynamics despite theoretical possibility

What Einstein's 1905 Brownian motion paper proved — the existence of atoms by explaining pollen's random motion

Brownian motion confirmed atoms' existence through pollen's erratic movement

What gravitational time dilation means — clocks run slower in stronger gravitational fields

"Gravitational time dilation: stronger gravity slows clocks relative to weaker gravity."

Why the Dirac equation has negative energy solutions — interpreted as positrons, confirmed by Anderson in 1932

Dirac equation predicts negative energy states, later identified as antiparticles, positrons, by Anderson's experiments

What the second law of thermodynamics says — entropy of an isolated system never decreases

Entropy in an isolated system always increases or remains constant

What the Olbers' paradox asks — why is the night sky dark if there are infinite stars (answer: finite age of universe)

Olbers' paradox: Night sky dark due to universe's finite age limiting starlight

What the no-cloning theorem prohibits — making an exact copy of an arbitrary unknown quantum state

The no-cloning theorem forbids creating identical copies of an arbitrary unknown quantum state

What the Aharonov-Bohm effect shows — electromagnetic potentials have physical effects even where fields are zero

Demonstrates non-zero electromagnetic potentials influence particle phase despite zero field presence

What the Carnot efficiency limit is — η = 1 - T_cold/T_hot, no heat engine can be more efficient

Carnot efficiency sets the maximum achievable efficiency for heat engines based on temperature ratios

What the Many-Worlds interpretation claims — all outcomes occur in branching parallel universes, no collapse

Many-Worlds posits simultaneous existence of all possible outcomes in separate, non-interacting universes

What Maxwell's demon thought experiment challenges — can information be used to decrease entropy

Maxwell's demon challenges the second law of thermodynamics by potentially decreasing entropy using information

Why neutrino oscillations proved neutrinos have mass — contradicting the original Standard Model

Neutrino oscillations imply mass differences, violating Standard Model's massless neutrino assumption

What the Chandrasekhar limit is — 1.4 solar masses, above which electron degeneracy pressure fails and a white dwarf collapses

Chandrasekhar limit: 1.4 solar masses, threshold for electron degeneracy pressure in white dwarfs

What BCS theory explains — superconductivity arises from Cooper pairs of electrons mediated by phonons

BCS theory explains superconductivity through electron pairing via phonon-mediated attraction

What the renormalization group does — explains how physics changes with the scale of observation

Renormalization group describes scale-dependent behavior in physical systems

What CP violation means — charge-parity symmetry is broken in weak interactions, explaining matter-antimatter asymmetry

CP violation allows for matter dominance over antimatter in the universe

What the train thought experiment in special relativity shows — simultaneity is relative to the observer's motion

Train thought experiment: Observers' simultaneity depends on relative motion

What universality means in phase transitions — different systems show identical critical exponents

Universality in phase transitions: identical critical exponents across diverse systems

Why time translation symmetry gives energy conservation — if physics doesn't change with time, energy is conserved

Time translation symmetry implies unchanging physics, thus conserving energy

What asymptotic freedom means — quarks interact more weakly at higher energies, earning the 2004 Nobel Prize

Higher energies reduce quark-gluon interactions, leading to asymptotic freedom

What confinement means — free quarks are never observed, they're always bound in hadrons

Confinement in quantum chromodynamics prevents free quarks, binding them in hadrons

What the CMB power spectrum tells us — the age, composition, and geometry of the universe

CMB power spectrum reveals universe's age, composition, and large-scale structure

What decoherence explains — the appearance of wavefunction collapse through interaction with the environment

Decoherence explains wavefunction collapse due to environmental interactions

Why GPS satellites must correct for both special and general relativistic effects — or positions drift by 10 km/day

GPS satellites account for relativistic effects to ensure precise positioning, averting a daily drift of approximately 10 km

Why rotational symmetry gives angular momentum conservation — if physics doesn't change with direction, angular momentum is conserved

Rotational symmetry implies invariance under spatial rotations, leading to conservation of angular momentum

What a Cooper pair is — two electrons with opposite spin and momentum bound through lattice vibrations

Cooper pairs: bound electrons with opposite spins and momenta via phonon-mediated attraction in superconductors

Why spatial translation symmetry gives momentum conservation — if physics doesn't change with position, momentum is conserved

Spatial translation symmetry implies uniform physical laws, thus conserving momentum

What gravitational lensing confirms — mass curves spacetime and bends the path of light

Gravitational lensing confirms that mass warps spacetime, bending light's trajectory

How does the phenomenon of quantum tunneling in semiconductor quantum dots exhibit discrete energy levels and quantized conductance at nanoscale dimensions?

Quantum tunneling in quantum dots confines electrons, creating discrete energy levels and quantized conductance due to wave-particle duality

How many types of fundamental forces are represented in the Standard Model of particle physics and which gauge bosons mediate each of these forces?

Four fundamental forces: electromagnetic (photon), weak (W and Z bosons), strong (gluons), gravity (graviton, not yet confirmed)

How do the results from LIGO and Virgo collaborations provide evidence for gravitational waves, thereby supporting the predictions of general relativity?

LIGO and Virgo detectors' measurements of gravitational wave signals confirm Einstein's general relativity predictions

How does the conformal structure in complex analysis impact the visualization of complex functions, particularly in relation to conformal mappings and their role in distortion minimization?

Conformal structures preserve angles, enabling distortion-minimized visualizations of complex functions via conformal mappings

How did the Pound-Rebka experiment of 1959 provide empirical evidence for the gravitational redshift predicted by general relativity?

Measured redshift of gamma rays in Earth's gravitational field confirmed gravitational redshift

What cosmological evidence from the Cosmic Microwave Background (CMB) anisotropies observed in 2003 supports the presence of dark matter in the universe?

CMB anisotropies indicate large-scale structure formation, consistent with dark matter's gravitational influence

What does Noether's theorem state about the relationship between continuous symmetries and conservation laws in physics?

Noether's theorem links each continuous symmetry to a corresponding conservation law

How does the Percolation Theory model explain the behavior of connected clusters in random graph structures during phase transitions?

Percolation Theory models predict critical thresholds for cluster formation and connectivity in random graphs

What does the Kochen-Specker theorem demonstrate regarding the nature of quantum observables and hidden variables theory?

Kochen-Specker theorem disproves non-contextual hidden variables in quantum mechanics

How does the Quantum Hall Effect demonstrate the quantization of the Hall conductance, and what role does Planck's constant play in this phenomenon?

Quantum Hall Effect: Hall conductance quantized as νe²/h, where h is Planck's constant

Which gauge symmetry underlies the unification of the electromagnetic, weak, and strong forces at high energies, and how does it manifest in the Standard Model?

SU(2)xSU(3) gauge symmetry unifies forces in the Standard Model, manifesting as weak and strong interactions

How does the Noether's theorem relate the conservation of energy to the symmetries of Lagrangian functions in classical mechanics?

Noether's theorem links conserved energy to time-invariance of the Lagrangian

Which Feynman diagrams represent the visual shorthand for terms in non-abelian gauge theory calculations in the context of quantum chromodynamics (QCD)?

Feynman diagrams for non-abelian gauge theory: gluon lines with self-interactions

What is the Bekenstein-Hawking entropy formula, and how does it relate to the black hole's surface area and event horizon?

S = k * A / (4 * l_p^2), relating entropy to a black hole's surface area

How does the concept of quark confinement in quantum chromodynamics support the idea that free quarks have never been observed due to the presence of a color force, which causes them to be bound within hadrons?

Quark confinement in QCD implies unobserved free quarks due to color force binding them in hadrons