Is a planet hot inside because it is still hot from beginning, or continuously heated?


Why is it impossible to make a monopole magnet?

What is the explanation of the non-existence of magnetic monopoles?


Definition of an "Observer" in regards to quantum physics and consciousness involvement

What is an observer in quantum mechanics?


Is the dimensionality of space considered a universal constant?

Has the concept of non-integer $(n+m)$-dimensional spacetime ever been investigated by theoretical physicists?


Can we transfer part of the angular momentum of light to mechanical objects?

Where does the photon orbital angular momentum go in light-matter interactions?


Why magnet attracts a magnet? Coz we know that magnetic force cannot change the kinetic energy..then why magnet attracts or repel other magnet?

How can magnets be used to pick up pieces of metal when the force from a magnetic field does no work?


Special relativity with horizontal mirror clock?

In relativity, what is the difference between a rod that is perpendicular to direction of motion and a rod parallel to the direction of motion?


What is the meaning of the integral of position?


Period $T$ of oscillation with cubic force function


Why don't mirrors violate conservation of momentum/do they get warm?

Do photons lose energy after radiation pressure is applied to a perfect reflector?


Ionisation energy of hydrogen: Why are kinetic and potential energy connected by $2 T = -V$ in the derivation?

Why is Kinetic Energy = (-) Total Energy and Potential Energy = 2 $\times$ Total Energy?


Adding spin and orbital angular momentum

Angular Momentum Addition Theorem - Sanity Check


Why we mutilply wavefunction with conjugate of it to obtain the probablity density of particle?

Why is $|\Psi|^2$ the probability density?


Hamiltonian formalism of General Relativity Textbook

References for cosmological perturbation theory in the ADM formalism


What's the direction of the current in this circle if a magnet is approaching (or distancing from) the circle?

How to determine the direction of induced current flow?


Are neutrinos and anti-neutrinos the same thing?


Compactification of additional dimensions

Why does string theory require 9 dimensions of space and one dimension of time?


Book recommendations to understand General Relativity


Does following relation holds for an interacting vacuum of QFT

Does the vacuum in QFT have nonzero energy or not?


Is Energy conserved in General Relativity

Is energy conserved in general relativity? Does $\nabla_aT^{ab}_{\rm matter}=0$ represent the conservation of energy and momentum?


Set of probabilities distributions inside a infinite square well

Multiple solutions for a particle in an infinite potential well


Why does motion under inverse square law follows elliptical motion?


Distance between particles in pair annihilation (or any other matter antimatter collision)

How close does a particle-antiparticle pair need to be for annihilation to happen?


Why is the Sun approximated as a black body at ~ 5800 K?


How is the Earth pushing "up"/"outwards" at $9.8\text{ m/s}^2$ in general relativity?


Discreteness of the universe and evidence for simulation

Does the Planck scale imply that spacetime is discrete?


Newton's 2nd Law: Why is this Mass times Acceleration?


Prove that the scattering operator is unitary


Where does the energy come from when a magnet moves a compass?


How come no information can travel faster than light when we can measure a black hole's mass?


Why are non-equally heavy objects falling at the same speed on the moon?

Why do two bodies of different masses fall at the same rate (in the absence of air resistance)?


Why are constant terms irrelevant in Lagrangians in quantum field theory?


If two waves cancel out, where does the energy go?

What happens to the energy when waves perfectly cancel each other?


Does the force of kinetic friction increase with the relative speed of the objects involved? If not, why not?


Does light accelerate inside event horizon

Speed of light in a gravitational field?


How to solve complex resistor combinations like the one given?

Resistor circuit that isn't parallel or series


Light is a high frequency electromagnetic wave. Can an LC oscillation circuit emit visible light?

Can an LC oscillator be used to generate visible light?


Why are oscillations so ubiquitous in nature?

Why is the harmonic oscillator so important?


Factor $1/2$ in work done by spring force


Physical meaning of same pressure on the same plan (hydrostatic paradox) with different weight above them

Pressure at base of 3 different dam designs


How do astronauts and spacecrafts float away into space if they're always under the influence of the Earth's gravity?


Why is current density a vector quantity while current is scalar?

Why does current density have a direction and not current?


Why does not the Moon escape from the Earth?

Why does the Moon not revolve around the Sun directly?


How does polaroid filter work at the atomic level?

what happens inside linear polarizer sheet (at microscopic level) when unpolarized light falls on it?


Is a big object also not well localised according to quantum mechanics?


How does the Hubble parameter change with the age of the universe?


Why do 2 bodies of different masses reach the ground at the same time?

Why do two bodies of different masses fall at the same rate (in the absence of air resistance)?


What is the Gravitational force between 2 bodies, when their centres of mass coincide?


How can two people on opposite sides of the Earth both be accelerated?


How does General Relativity explain the gravitational attraction between two distant bodies?

How can we recover the Newtonian gravitational potential from the metric of general relativity?


Why atom has the straight discrete energy levels?

Electron shells in atoms: What causes them to exist as they do?


What does it mean "information can't be cloned"?

What exactly does No cloning mean, in the context of Quantum Computing?


Is the total enthalpy of the universe constant?

Is the total energy of the universe zero?


What is the behavior of the normal force during uniform circular motion?


Why is Lorentz symmetry considered sacred?


Comparing Theory of Relativity with Newtonian gravity


Is the wave-particle duality a real duality?


Why does electron orbital circumference have to be in multiples of de Broglie wavelengths?


Law of cosines in Time dilation formula derivation

What if a light clock travels perpendicular to mirrors that make up the clock?


Gravitational field intensity inside a hollow sphere


What is the relation between electromagnetic wave and photon?


What does it mean that image if formed in front of mirror


Why does current remain constant in a series circuit although the rate at which they flow deceases due to the collisions they go through?

Why doesn't current decrease in series combination?


Why revolutions (or turns) are dimensionless?

Are units of angle really dimensionless?


If gravity can be thought of as masses leaving dents on a spacetime 'sheet', what is holding up that sheet?

How exactly does curved space-time describe the force of gravity?


Does Electrostatic potential energy bend Space-time?

Why is spacetime curved by mass but not charge?


What happens if you poke a black hole with a stick?

Thought Experiment - Poking a stick across a Black Hole's Event Horizon


What are the differences and advantages of the integral and differential forms of Gauss's law?

What are the differences between the differential and integral forms of (e.g. Maxwell's) equations?


Why is order of electron orbital filling not completely sequential?

Why do electrons not fully fill up all the orbitals sequentially?


What exactly does the *frequency* of a photon mean?


Rigorously proving equal tension on both ends


Is the vacuum of a local ${\rm U(1)}$ gauge theory unique?

Review: If true, what makes the vacuum of a local ${\rm U(1)}$ gauge theory unique?


Why does dust form islands on top of water?

Why do Oreo crumbs float to a single glob at the very center in a glass of milk?


Could situation where water does not pour out of a bottle change if different liquid is used

Physics of the inverted bottle dispenser


How to treat differentials and infinitesimals?


What is time? Does it flow linearly? If so, how are we sure?

What is time, does it flow, and if so what defines its direction?


Questions about the Fermi-Dirac distribution at $T=0.$


What's the shape of the flame for a candle in parallel plate capacitor?


Potential drop in a wire having negligible resistance


What is the difference between degree celsius and celsius degree?


When we light a candle or kerosene lamp, why fire is turning to a drop shape?


How to convert pressure limit in 3D to 2D?

How do we define capillary number in 2D (two dimensions)


Zero work by magnetic field but still motion of particle?

How can magnets be used to pick up pieces of metal when the force from a magnetic field does no work?


What is the use of $i=\sqrt{-1}$ in plane wave equation?

What does the complex electric field show?


In a circuit, does a battery create electrons which it 'injects' into the copper wire?

Where do electrons in electricity come from?


Why are there no operators in classical mechanics?

Are there linear operators and vector spaces in classical physics?


Physical intuition behind level repulsion?

Why is the second order perturbative correction to the ground state energy always down?


What are some books that teach to apply Lagrangian methods on simple systems of Physics I?


Is the work-done by a magnetic field on a moving point charge zero?


Why does the weighing balance restore when tilted and released


Carnot Cycle with adiabats crossing on $pV$ diagram


Non-uniqueness of Lagrangian and quantization

Why there is no unique "recipe" for quantization of a classical theory?


Why are spatial derivatives of a field not used to define the conjugate momentum?

Lagrangian to Hamiltonian in Quantum Field Theory


Derivation of the Schwarzschild solution

What exactly is the difference between a Ricci-flat manifold and Minkowski space?


Regarding difference in dimensions of a physical quantity in different unit systems


why can't electromagnetic waves make through holes that are smaller than the waves wavelength


How can a magnet in a magnetic field have a potential energy, when the magnetic field is not conservative?

Why don't we define potential due to a magnetic field?


Justification of the energy and momentum operators in quantum mechanics

How to derive or justify the expressions of momentum operator and energy operator?


Basic GR question: For two arbitrary observers measuring same two events, is $ds^2$ numerically the same for both?

How to show the spacetime interval is invariant in general?


What does Dr. Krauss mean by a universe from "nothing."


Why does time dilation imply length contraction?

Time dilation clock experiment: what would happen if the clock were flipped 90 degrees?


What happens to the rotational kinetic energy?


Why the integral of a force gives Energy?

Why is the potential energy equal to the negative integral of a force?


How does an electron deexcites during stimulated emission?


Density of states of non-rationally invariant dispersion relations (Energy bands)

Density of states for arbitrary dispersion relation


Spinor indices in $\not p = m_P$ (mass renormalization)

Spinor field normalisation from poles in the propagator


Schrödinger's equation for hydrogen atom (azimuthal part)

Angular equation for Schrödinger's equation in 3D


Does an electron have a fixed orbit in reality?

Is the uncertainty principle a property of elementary particles or a result of our measurement tools?


Position vs time of electromagnetic force

How to find distance travelled when the change in the force of gravity is not negligible?


What's the status of the axiomization of physical theories?

What happened with Hilbert's sixth problem (the axiomatization of physics) after Gödel's work?


If Newton's third law is true, why do things compress?

If Newton's third law is true, why can we sink in sand?


Can we describe all forces as a curvature in space-time?

Can all fundamental forces be fictitious forces?


Is Heisenberg uncertainty principle really a good justification for the impossibility of$\ 0$ K?

Absolute zero and Heisenberg uncertainty principle


Confusion about effect of atmospheric pressure on depth at which an object floats


Momentum conservation in ball and massive wall collision

Contradiction between law of conservation of energy and law of conservation of momentum?


Why Angular velocity is a vector quantity and why it got direction perpendicular to the plane


If I run along the aisle of a bus traveling at (almost) the speed of light, can I travel faster than the speed of light?


How does a photon decide what to hit along it's path?

Time and distance in a photon's frame of reference


Is there a proof of the time-dependent Schrödinger equation?

How can one derive Schrödinger equation?


Book recommendations for fluid dynamics self-study


How does a string store information during wave superposition?

Why do travelling waves continue after amplitude sum = 0?


Do particles always flow from high to low pressure?


Would a room temperature superconductor break the laws of thermal dynamics?

Why doesn't this magnetic perpetual motion machine work?


Why is Newton's First Law not considered a vacuous statement?


How do photons travel? Do they have a specific shape?


Adding a term to the Lagrangian Density without changing Lagrange's Equations

Does a four-divergence extra term in a Lagrangian density matter to the field equations?


Is the speed of quantum entanglement interaction greather than $c$?

Does entanglement have a speed or is it instantaneous


Gravitational Oscillation and Kepler's Third Law

The Time That 2 Masses Will Collide Due To Newtonian Gravity


If a mass moves close to the speed of light, does it turn into a black hole?


How to ensure light only flows in one direction?


On force being directly proportional to the rate of change of momentum

Are Newton's "laws" of motion laws or definitions of force and mass?


What does the cosmic neutrino background look like today, given that neutrinos possess mass?


Thermal Heat on white and black vehicles

Radiation– white vs black house, hot or cool?


Any solutions to Veritasium's hydrodynamic levitation?


Energy conservation on expanding universe

Is the total energy of the universe zero?


Is it possible to have a Gas heavier than a liquid?


Prove that an electron in a hydrogen atom doesn't emit radiation


Why Does Amplitude Have no Effect on the Energy of a Light Particle?


Does a charged particle experience force in presence of light

What is the magnitude of the force on a charged particle due to electromagnetic radiation?


How can a photon have no mass and still travel at the speed of light?


What is the proof that a force applied on a rigid body will cause it to rotate around its center of mass?


Why is displacement equal to the area of velocity-time graph?

How area under Velocity-Time graph represents magnitude of displacement?


Field inside a hollow sphere uniformly charged

Gravitational field intensity inside a hollow sphere


Is it always true that a solid object(geometrical figure) has less moment of inertia than its corresponding hollow one?

Why is the moment of inertia (wrt. the center) for a hollow sphere higher than a solid sphere (with same radius and mass)?


When we push on a wall, why isn't there any work done?

Why does holding something up cost energy while no work is being done?


Equal and opposite reaction - forces coming in pairs - or just common sense?


Can electromagnetic fields be used to deconstruct and reconstruct atoms?


Background Subjects Required to Understand Quantum Field Theory?


What does it mean for a battery to be 1.5 Volt?


Does time really slow down in relativity, or is it an illusion caused by the Doppler shifting of light?


Why pressure is a scalar instead of a vector?

Define Pressure at A point. Why is it a Scalar?


Do the wires having AC current emit EM waves?


What is the difference between TISE and TDSE, physically , how to visualize it?


Does the curvature of spacetime theory assume gravity?


Why bar magnet can produce magnetic field?


Why does the presence of multiple items in a microwave require you to cook them longer than you would with the singular item?

Does a microwave take longer to heat two bowls of soup?


What is the actual meaning of dot product of 2 vectors?

What is the physical significance of dot & cross product of vectors? Why is division not defined for vectors?


Temperature of the system stays constant even though it moves?


Why is normal force sometimes called "reaction force"?


Intuition behind quantum CNOT gate applied to a pair of electrons

How is CNOT operation realized physically?


A confusion between geocentric and heliocentric model

What made us think that Earth moves around the Sun?


How would primordial black hole forms if expansion of space overwhelms gravity?

How likely are Primordial Black Holes to form in the early universe?


Why can't $\psi(x) = \delta(x)$ in the case of Harmonic oscillator?

Hilbert space of harmonic oscillator: Countable vs uncountable?


Differences between pure/mixed/entangled/separable/superposed states


Can an atomic nucleus contain both particles and antiparticles?

What happens if we put together a proton and an antineutron?


How does pressure cooker increase cooking speed?


Any recommended resources for a total beginner with no real maths training?


Fermat's principle: when does light actually travel along the local maximum of accumulated phase?

Examples in which the light maximizes the optical path length


Finding the uncertainty of coherent states using operators

Harmonic oscillator coherent state expectation values


If some matter slows light going through it, is actual causality also slowed?

Are special relativity calcs affected by media?


Virtual pair of particle-antiparticles trajectory

Are vacuum fluctuations really happening all the time?


Getting a Conserved Quantity from a Lagrangian

Noether Theorem and Energy conservation in classical mechanics


Gravitational lensing redshift around a Kerr black hole

Do light experience Doppler shift along and against frame dragging?


Why does cold metal seem colder than cold air?


When a solid is dissolved in a liquid, is it still a solid, what about individual atoms or molecules in a vacuum?

If you have a single atom in a box, what state of matter would it be in?


Why are elements with even atomic number more abundant?


Does a geodesic always extremize its path length?

Geodesics: Straightest or Shortest? When and Why?


What does it mean to say "Gravity is the weakest of the forces"?


Explain reflection laws at the atomic level


Where does the energy for osmosis come from?


Book recommendation for second look at GR


Derivatives with Two Indices in Electromagnetic Lagrangian

Derivation of Maxwell's equations from field tensor lagrangian


Does back E.M.F. create a second back E.M.F. which creates a third back E.M.F. and so on?

Does the magnetic field due to the current from a motional emf induce a counter emf?


Can others see us many years ago relative to them?

If you view the Earth from far enough away can you observe its past?


Scattering, Perturbation and asymptotic states in LSZ reduction formula


Difference in the age of Earth equator region when compared to the age at the pole regions


The average velocity of galaxies in a galaxy cluster

Why is speed measured along the line of sight (LOS) a factor $\sqrt{3} $ smaller for randomly distributed velocities?


Good introductory book about Group Theory?

Comprehensive book on group theory for physicists?


Is there anything analogous to wavefunction collapse in Quantum Field theory?

How does wave function collapsing fit into QFT?


Earth's unimpeded rotation for billions of years

If there is friction and everything stops on earth why does earth not stop due to friction?


Deriving system properties from energy spectrum

In quantum mechanics, given certain energy spectrum can one generate the corresponding potential?


Divergence of $\frac{ \hat {\bf r}}{r^2} \equiv \frac{{\bf r}}{r^3}$, what is the 'paradox'?


Given time dilation from traveling near light speed, would a spacecraft be able to reach any arbitrary distance including to another galaxy?

How long would it take me to travel to a distant star?


Good introductory book about general relativity at undergraduate level?


In empty space what happens to the lights energy that is lost to the doppler effect go to?

Conservation of energy and Doppler effect?


Unit of measurement of torque/moment of force


How was the half-life of Uranium 235 determined and by whom?

How do we know that some radioactive materials have a half life of millions or even billions of years?


How do we know that $SU(3)$'s generators are Gell-Mann matrices?


Conservation of Energy vs Expansion of Space

Is the total energy of the universe zero?


Excite hydrogen with lower frequency photon

Can an electron jump to a higher energy level if the energy is insufficient or exceeds the $\Delta E$?


Why does changing the number of protons cause such a fundamental change in an element?

Why does amount of protons define how matter is?


How does the Event Horizon Telescope capture the image of the black hole if no light can escape near the event horizon?

Light emission from the vicinity of a black hole


Deriving the square of the angular momentum operator in spherical coordinates

Square of angular momentum operator in spherical coordinates


Light Travels in straight line even in gravity


Why doesn't decoherence spoil the double slit experiment?

Decoherence and Young's double slit experiment


Why does the direction of a dipole moment go from negative to positive charge?


Which postulate of GR requires that $ds^2=g_{\mu\nu}(x)dx^\mu dx^\nu$ must be invariant?

How to show the spacetime interval is invariant in general?


How degenerate time independent perturbation theory works?

Struggling to understand degenerate perturbation theory


Total divergence term in derivation of Noether's theorem

Is the change in the Lagrangian always a total derivative for symmetry transformations of the action?


Why am I getting two different expressions for capacitance?

A problem of missing energy when charging a second capacitor


What force acts on a small piece of a free, spinning ring?


How electric field and magnetic field propagate through vacuum where there's no charge present?

How do electromagnetic waves travel in a vacuum?


Why is causality preserved in special relativity?


Critical temperature of Bose-Einstein condensation


How is reflection explained in quantum optics?

Explain reflection laws at the atomic level


How to find distance travelled when the change in the force of gravity is not negligible?

Is acceleration due to gravity constant?


Is "physical damage" proportional to momentum or kinetic energy?

What causes damage, kinetic energy or momentum?


Version of the Relativistic Train Paradox

Special Relativity - Regarding the Simultaneity of Events During the Train Paradox


The use of the commutators in quantum mechanics: explanations

Heisenberg Uncertainty Principle scientific proof


Why does everyone seem to think that moving clock appear to tick slower?


Is the orbit of the planets around the Sun chaotic?


Does the technology exist to generate AC current with a frequency high enough such that when used in a circuit, could generate visible light?

Can an LC oscillator be used to generate visible light?


Reason for the negative sign in the gravitational potential $-GM/r$?

How to understand whether potential energy increases or decreases?


Reversed effective force in D'Alembert's Principle


Why exactly does light bend when it enters a different medium?

How are classical optics phenomena explained in QED (Snell's law)?


How can we tell if the Earth is spinning without any external references?


Could someone tell me how Sir Issacc Newton derived the equation for the Universal law of gravitation?

How was Newton able to guess that gravitational force is inversely proportional to distance squared?


Virtual particles, conservation of energy & the fabric of space

Are vacuum fluctuations really happening all the time?


Why is the electric dipole moment of the nucleus of an atom equal zero?

Why don't the nuclei have an electric dipole moment?


Common observables and associated operators: operator momentum


Is the mass needed to create a black hole greater if the black hole is moving?

If a mass moves close to the speed of light, does it turn into a black hole?


When two photons annihilate each other through destructive interference, where does the energy go?

What happens to the energy when waves perfectly cancel each other?


Permanent magnet attraction from Maxwell's equations / Lorentz force

How permanent magnets work?Are they working with motion of electrons?


$\delta Q = dU + \delta W$. Why is it $dU$ while others are partial differentials?


Perturbing about the Renormalized Field Theory: What justifies perturbing if the counter-terms are large?

How does a perturbation theory make sense in quantum field theory?


Prove that qubits can be represented on a unit sphere, avoiding the density matrix formalism


What is the biggest time dilation an object can have compared with Earth?

Does time pass fastest in isolated, resting space?


How can a horse move a cart if they exert equal and opposite forces on each other according to Newton's third law?

Given Newton's third law, why are things capable of moving?


Why is flow of current considered opposite to flow of electrons even by "convention"

Why is the charge naming convention wrong?


Work Enegy Conservation & Rolling Bodies


How Lagrangian equations of motions can be obtained from Newton's laws?

Is there a proof from the first principle that the Lagrangian L = T - V?


Is current a tensor or a scalar quantity?


Is there more to the the conventional explanation of 'Why is the sky blue?'?


Relevance of non-quantized relativistic string theory

What are the reasons to expect that gravity should be quantized?


How much is the universe blueshifted at a black hole event horizon?

Do free falling observers see gravitational blueshift?


Where is energy dissipated on charging a capacitor?

What happens to half of the energy in a circuit with a capacitor?


Force required to insert dielectric in a capacitor connected to a battery

Oscillations of Dielectric Slab in Parallel plate capacitor


What would happen if the value of the gravitational constant would become twice as large?

Is it possible to speak about changes in a physical constant which is not dimensionless?


Understanding why $\frac{\partial (F_{\mu \nu} F^{\mu \nu})}{\partial (\partial_\lambda A_\beta)}=4 F^{\lambda \beta}$ in Maxwell's Equations

Euler-Lagrange equation in curved spacetime: how to calculate $\partial \mathcal{L}/\partial(\nabla_\nu A_\mu)$?


How is Hamilton's first equation useful in solving mechanics problems?

What's the point of Hamiltonian mechanics?


Centre of Mass of Electrons in an Orbital

The position of center of mass of electron cloud in an atom


In Bell's inequality, why is the expected correlation given by $C_q(\mathbf a,\mathbf b)=-\mathbf a\cdot\mathbf b$?

Prove that in Bell's inequality $\langle{\Psi}|\left(\bf{\sigma}\cdot\bf{a}\right)\left(\bf{\sigma}\cdot\bf{b}\right)|{\Psi}\rangle=-\bf a \cdot\bf b$


Build a ring around Earth, then remove the supports


Analytic Continuation: Replacement of $t \rightarrow - i \tau$ Mathematical Justification

Why do people use real values for the Wick-rotated time $\tau$?


Does a free particle always follow the trajectory of shortest distance?

Can Lagrangian be thought of as a metric?


If a black hole bends light what does to a beam that arrives at a zero degree angle directly towards the singularity?

Speed of light in a gravitational field?


How to interpret $\langle x|\hat Q|x'\rangle$ for a quantum mechanical operator $\hat Q$?


What's a simple experiment to perform, near the equator, to show the rotation of the earth?


A good modern introduction to the information theoretic view of entropy?

Reference for statistical mechanics from information theoretic view


Why do shadows from the sun join each other when near enough?


Why does holding something up cost energy while no work is being done?


A good **modern** introduction to the information theoretic view of entropy?


If photons are particles why gaps don't form between radially emitted photons even at astronomical distances?

As light from a star spreads out and weakens, do gaps form between the photons?


Information Propagation at the Speed of Light

Is it possible for information to be transmitted faster than light by using a rigid pole?


How do a black hole made from electrons produce EM field?

Detection of the Electric Charge of a Black Hole


Does time dilation mean an object moving faster advances faster in time?


Difference between scalars, vectors, matrices and tensors

What is the difference between a spinor and a vector or a tensor?


A oil drop is half immersed in water. What will be the direction of the force of surface tension on the drop?

Surface tension: the paper clip experiment


How does a photon 'perceive' the 2-D plane in which it perceives itself?

How does a photon experience space and time?


Neutrino flavor models from irreducible representations of discrete groups

Why do all fields in a QFT transform like *irreducible* representations of some group?


How do we know that $F = ma$, not $F = k \cdot ma$


How to prove Gauss law geometrically (without coordinates) from Coulomb's law?

How is Gauss' Law (integral form) arrived at from Coulomb's Law, and how is the differential form arrived at from that?


Why is the metric used in physics a squared norm?

Can I use a higher rank tensor field as the metric field?


How would Special Relativity work if the universe were periodic?

Symmetrical twin paradox in a closed universe


Why do we calculate a charged conductor sphere's potential with respect of the centre?

Confused about the electric field at the surface of a conductor


In the heliocentric model of planetary motion, is Sun assumed to be stationary at the center?

Are planets actually moving in elliptical orbits around the Sun or do they move in circular orbits around their center of mass?


Why is the meter considered a basic SI unit if its definition depends on the second?


Will deceleration in a geostationary orbit kick me into a higher orbit?

If we threw a baseball from the ISS, could we deorbit the ball?


Why do sun light rays that come through clouds not look parallel, despite it being so far?

Why do sunbeams diverge even though the sun is much more than a few kilometers away?


Is Force a fundamental concept just like position and time?


Why the purple and red light entering the prism is broken at different angles?

Why do prisms work (why is refraction frequency dependent)?


What happens if I place a charge inside a hollow conductor and fix it?


How to find the net electric force exerted on a uniformly charged rod by another, same rod on the x-axis (they don't touch)?

The force between two sections of uniformly charged line


What does lowercase-delta mean in Noether's first theorem?

Difference between $\Delta$, $d$ and $\delta$


Explain reflection laws at the atomic level


Why don’t electrons fall into the nucleus of an atom?

Why don't electrons crash into the nuclei they "orbit"?


Is it possible to transfer kinetic energy from rigid body 1 to body 2 and conserve total kinetic energy?

Are there perfect elastic collisions in Nature?


Book(s) fills the gap from introductory thermo to nonequilibrium thermo/stat mech for self-taught student?

Modern textbook on statistical field theory with an emphasis on applications to non-equilibrium phenomena?


On the spectrum of a quantum mechanical system


Can the gravitational attraction from a particle ever decrease to zero if it goes far enough away from us?

How far apart do two objects have to be for there to be negligible force between them?


What happens to a light ray after it enters a perfect sphere?

What happens to light in a perfect reflective sphere?


Which is responsible for electric shocks: voltage or current?

What causes an electric shock - Current or Voltage?


How is electro-magnetic wave formed without medium?

Why don't electromagnetic waves require a medium?


How electrons really revolve around nucleus through nodal plane in $p$ orbital?


Cool a room with a fan, what sens orientation?

On a hot day, when it's cooler outside than in; is it better to put a fan in an open window pointing inwards or outwards?


How does the trace acts over one of the two entangled qubits?

Why is the partial trace of this subsystem equal to this?


How does a unitary operator acts on an entangled $|\psi\rangle$?


what is meant by completeness of Hilbert space?

What is the physical meaning of a "complete" Hilbert space in QM?


Can anyone provide a simple, inuitive explanation for Noether's Theorem?

Can Noether's theorem be understood intuitively?


Internal mechanism of normal contact force in a lift or other situations


Does Newton's Third Law apply to gravity?

Does Newton's 3rd law of motion apply when a person is standing still on a ground?


How to determine the direction of instantaneous acceleration in a 2D motion?

Derivation of formula of normal acceleration


What do we mean, concretely, by the unit $\rm N\:m$ (newton $\cdot$ meter)?

What do units like joule * seconds imply?


Could the singularity of a black hole just be an iron / dark matter sphere?

Can we have a black hole without a singularity?


Online Sources for University Level Physics (And Mathematics)


Why do color of things fade and where it goes?


Relation Between Cross Product and Infinitesimal Rotations, Generators, Etc

$SO(3)$, orbital angular momentum, vector product


What is this optical illusion in which airplane propellers appear to rotate backwards? How is it explained?


Why does not dark matter gather and form celestial bodies?

If dark matter only interacts with gravity, why doesn't it all clump together in a single point?


If particles are points, then aren't atoms empty space?


Why the electric field of an infinity line is dependent on distance?

Why does the electric field of an infinite line depend on the distance, but not on an infinite plane?


Given Newton's third law, why are things capable of moving?


What is the formula for electromagnetic force on magnetic charge in condensed matter?

Is the Lorentz force expression valid for magnetic field created by a magnetic monopole?


What happens to a (moving) magnetic-dipole in an external electric-field?

The spin-orbit interaction for a classical magnetic dipole moving in an electric field


How can Quasars emit anything if they're black holes?


What is the relation between electromagnetic wave and photon?


Is the Universe inside the event horizon of a white hole or a black hole or none?

Is the observable region of the universe within the event horizon of a super-massive black hole?


How exactly does the curvature of space-time cause objects to "fall" into another object

How does "curved space" explain gravitational attraction?


Does Hawking Radiation Violate General Relativity?


Arriving at the Quantum Mechanial Potential From The Energy Eigenvalues

In quantum mechanics, given certain energy spectrum can one generate the corresponding potential?


What if quantum mechanics and general relativity are not connected?

What are the reasons to expect that gravity should be quantized?


Superposition principle forbids quantisation?

What is the energy of a superposition of energy eigenstates?


Is force really defined by the second axiom of Newtonian mechanics?

Are Newton's "laws" of motion laws or definitions of force and mass?


If eardrum vibrates when hit, why don't we hear the air in the room that is continuously moving?

How loud is the thermal motion of air molecules?


How does the hydrogen atom actually "look like"?


Ampere's law for a loop with zero enclosed current

Getting incorrect results applying Ampere's law


How to reach $U = mgh$ Using Newton's Law of Universal Gravitation?

Near Earth vs Newtonian gravitational potential


What this quantum field operator represents $ b_{in}(t) = \frac{1}{\sqrt{2 \pi}} \int e^{-i \omega t} b(\omega)$?

What does it mean to Fourier transform a ladder operator (in the input-output formalism)?


Would every particle in the universe not have some form of measurement occurring at any given time?

What is the quantum mechanical definition of a measurement?


What does 'Truth-level' mean in Particle Physics?

Differences between reconstruction- and generation-level variables in HEP data


Calculating angle of projectile motion with constant initial velocity

Angle required to hit the target in projectile motion


Do we know, or at least have a strong argument for the fact that for a given time interval, we can always find a smaller time interval?


What causes atoms to have their specific colors?


Can electric energy be generated from only heat if the heat is uniformly distributed along the system?


Why is linear momentum not conserved for a particle in a central force?

Is linear monemtum conserved with in angular momentum?


The refraction through hot air around a candle flame


Why does Newton's Third Law actually work?


Understanding the meaning of thermodynamic work more clearly

Are we doing work when we compress a ball?


Noether's theorem for fields and infinitesimal transformations

Noether's Theorem: Lie groups vs. Lie algebras; finite vs. infinitesimal symmetries


What prevents galaxies from collapsing towards the galactic center?

Why doesn't the Moon fall onto the Earth?


Does a neutral object has an electric field of its own?

Is there an electric field around neutral atoms?


Quantum Field interaction transferred via "exchanging fermions"

Is there some special case where a fermion can mediate a force?


Infinite series of derivatives of position when starting from rest


If the Schwarzschild radius of the universe is bigger than the universe, how come the universe didn't collapse into a black hole?


Multiple measurements of the same quantity - combining uncertainties


Why is the equation for friction so simple?


Why can bound energy eigenstates be written as real functions?

When Eigenfunctions/Wavefunctions are real?


Is plane wave equation $\Psi(\mathbf r,t)=\Psi_0e^{i(\mathbf k \cdot \mathbf r-\omega t)}$ for quantum-mechanical wavefunctions really complex?

Is there a direct physical interpretation for the complex wavefunction?


Why do black holes warp spacetime so much more than stars that have the same mass?

When a star becomes a black hole, does its gravitational field become stronger?


What causes a moving positive point charge moving right in a uniform into the page magnetic field to specifically move upwards? why not downwards?

In electromagnetism, why does nature prefer the right-hand rule over the left-hand rule?


Why alpha particles instead of hydrogen or deuterium nuclei?

Why are alpha particles such a prominent form of radiation and not other types of nucleon arrangement?


Heisenberg's derivation of Schrödinger's Equation


Disparity in the equations of motion for a particle in a central field

How can you solve this "paradox"? Central potential


Why is the centre of mass displaced even when external force is 0?


Two formulas for current: how are they the same?

Equivalence of two Distinct Definitions of the Current Density $\textbf{J}$


Is it possible to think an example of refraction in which Fermat principle involve a maximum without using reflection?

Examples in which the light maximizes the optical path length


How does gravity escape from a black hole?


What if you pointed a laser away from a black hole while falling into it?


How is rotational information transferred to a singularity?

How can a singularity in a black hole rotate if it's just a point?


Why static friction does work on rolling bodies?

How can a rigid body's weight do work on it to make it rotate?


Does a hole have a spin? If yes, how to determine its direction?

How do electron holes have spin, and how do they interact with "real" particles / vice versa?


Calculations of Earth falling into the Sun if it suddenly stopped orbiting?

What if the Earth stops in its orbit and instead falls straight towards the Sun?


Does string theory remove the singularity of black holes?

What does string theory predict for the singularity inside a black hole?


Can wavefunctions always be separated into a product of spatial and spin parts?

When is separating the total wavefunction into a space part and a spin part possible?


Are electromagnetic and gravitational waves the only known types of waves that can travel in empty space?


Does a quantum commutator exist for energy and time?

What is $\Delta t$ in the time-energy uncertainty principle?


Resistor circuit that isn't parallel or series


If inertia is affected by velocity, and velocity is relative, doesn't that mean that inertia is frame-dependent?

If velocity is relative, how can mass (inertia) be coordinate independent?


Are there any real examples of Infinite, or possible infinite, in our universe?

Does infinity exist in physical systems?


Error Propagation: Why using derivatives instead of the function

Why is propagation of uncertainties quadratic rather than linear?


Is it possible for information to be transmitted faster than light by using a rigid pole?


Quantum interferometer with floating mirrors

Why doesn't a typical beam splitter cause a photon to decohere?


Why isn't the law of entropy applicable in the other direction of time?

Doesn't entropy increase backwards in time, too?


About the Lie algebra of the angular momentum Poisson bracket structure

Poisson brackets of three dimensional angular momentum and its Lie algebra


What is the electric field inside this shell?

Is Gauss's law wrong, or is it possible that $\int_s{\vec E} \cdot d\vec{s}=0$ does not imply $\vec E = 0$?


If we connect the two terminals of a semiconductor diode with a simple wire, then will the current flow?

Why isn't there a potential difference across a disconnected diode?


What equation precisely defines the epoch of recombination?

How precisely can we date the recombination?


Hawking radiation and virtual Exotic matter


For Einstein's equation $E= mc^2$ is it energy that increases or mass as the velocity increases?

Why is there a controversy on whether mass increases with speed?


Looking for a physics textbook on fluid mechanics

Book recommendations for fluid dynamics self-study


Potential Difference and Current dependence

Why, microscopically, is the voltage drop across a resistor affected by the current through it?


When does mass get converted into energy?

What keeps mass from turning into energy?


If we divide the second equation of motion by time $t$, why don't we get the first equation of motion where has $1/2$ come from?

Why there is a $\frac{1}{2}$ in the distance formula $d=\frac{1}{2}at^2$?


Why is torque measured about the centre of mass?

Why does a body always rotate about its center of mass?


Gravitational time dilation at a point between two stars?

Would Gravitational Time Dilation still apply between two gravitational sources?


Optical microscope magnification limits?


What does negative time mean or what does it show?


The question of the second law of thermodynamics

What is the reason of $dT/dh = 0$ in the gas column?


How does a photon released from particle A interacting with particle B, entangle them both?

How does a photon released from particle A interacting with particle B, entangle them?


Electric field in center of non-conducting sphere with non-uniform charge distribution from Gauss's law


Lagrangian formulation compared to the Newtonian formulation: connection high schools with the universities

Advantages of Lagrangian Mechanics over Newtonian Mechanics


What principle of quantum mechanics tells us that harmonic fluctuations of a field act like localized particles?


Why is there no gravitational magnetic field? (Or, is there?)


How does current density depend on diameter of wire?

Does drift velocity depend upon cross sectional area of the conductor? If yes then how?


What determines the height at which a superconductor hovers?

Effect of strength of magnetic field on the height of a levitating superconductor?


Looking for a good book on Differential Equations


What would happen if you tried to suspend an object half in the horizon of a black hole?

Another layman blackhole question, pulling one end of a string out from behind the event horizon


Why is $Q=p$, $P=-q$ a canonical transformation from the perspective of 2 variational principles satisfying boundary conditions?

Modified Hamilton's Principle overconstraining a system by imposing too many boundary conditions


Why is angular displacement not a vector?

If angular velocity & angular acceleration are vectors, why not angular displacement?


What are the good references on theory and applications of path integrals and partition functions in theoretical high energy physics?

Textbook on QFT in curved space-time via path integrals


What determines if an object will stay in a planet's orbit?

Under which conditions do two moving bodies start orbiting each other around their center of mass?


Electrons in the quantum mechanical model of the atom

What do atomic orbitals represent in quantum mechanics?


Wave function on bound state expectation value is zero

Expectation of momentum in the bound state


Atoms do not have colour, but objects which are nothing but the assembly of atoms have colour! How is that possible?


Where does the energy go when I short a capacitor?


Divergence of $\frac{ \hat {\bf r}}{r^2} \equiv \frac{{\bf r}}{r^3}$, what is the 'paradox'?


Why do we get this formula for the action for Maxwell theory?


Wavelength and Wavenumber not matching from Spectracalc

The strange thing about the maximum in Planck's law


Is there a good physical simulation software (mainly refers to the rigid body mechanics simulation)?

Simulation software to solve high school level mechanics problems


Two-body problem: equal mass keplerian orbit?

Solving Keplerian two-body problem numerically?


Why is the gravitational force always attractive?


Why does the mass of small objects not cause them to "pull" Earth towards them as slightly different speeds, as they fall to Earth?

Don't heavier objects actually fall faster because they exert their own gravity?


Why do we even need Hamiltonian formalism if Lagrangian formalism is basically the same at the basic level?

What's the point of Hamiltonian mechanics?


Are there any real life applications of Quantum Field Theory (QFT)

Are there any inventions/applications in our world based on QFT?


How did Newton discover the universal law of gravitation?


Should the CNB be comoving with the CMB?

Reference frame for the Cosmic Neutrino Background


Why "vacuum" in vacuum Rabi splitting (VRS)?


Is there an action reaction pair of forces when an object accelerates due to a pull/push?

Given Newton's third law, why are things capable of moving?


Does time expand with space? (or contract)


Uncertainty of the translational effect of a force that does not pass through the center of mass of an object


How does temperature differ from mean kinetic energy?

When is temperature not a measure of the average kinetic energy of the particles in a substance?


How can we show that pressure is exerted sideways too?


How does maximization of entropy imply minimization of energy?

Why does the nature always prefer low energy and maximum entropy?


Given equations of motion, how can we check if there is a lagrangian from which we can derive them?

How do I show that there exists variational/action principle for a given classical system?


S. Weinberg, “The Quantum theory of fields: Foundations” (1995), Eq. (9.2.15)


Understanding Multivariable Calculus without Hand-Waving

Book covering differential geometry and topology for physics


What are the main issues with gauge theories of gravity?


How current induced when magnet moves in coil?

Why does electromagnetic induction actually occur?


What is "power per unit frequency" in black body radiation?

What does 'per unit frequency' refer to?


What causes changes in frequency in the Nation Grid electricity supply?

How does load affect frequency on the power grid?


Is it possible to measure the speed of Time?

Is there a device that could measure the speed of time?


Significance of the negative sign in $V=-\int \vec E · \mathrm d\vec r$

Relation between Electric field and potential


Good introductory book to computational physics

Textbook recommendation for computational physics


Does all measured quantities by Hamiltonian operator should be real valued?

Why do we use Hermitian operators in QM?


Is mass slowly destroyed when force of gravity is applied?


How much force is required to lift the back of a 2,480 lb car in the air from the bumper?


Relative velocity between 2 frames of reference


How can an observer know that he is in an accelerating reference frame?

Is conservation of momentum and energy valid for non-inertial frames?


What is causing the current sinusoidal delay regarding voltage in inductive circuits?

Why does inductor current lag the applied voltage at its terminal by 90 degrees?


Reference Request: An introductory book on Kinetics, similar to Schroeder's on thermodynamics

Recommendations for statistical mechanics book


What is the (triplet) eigenstate for two electrons?

Ground state of two electrons in one dimensional S.H.O


Why are there two photons in pair production Feynman diagram?

Photon pair production at relativistic speeds?


Why does a rainbow only form with a 42° angle?


Divergence of a Vector Field - Surprising Result


What is the objective and reasoning of no slip condition?

No-slip boundary condition for viscous fluids


Buoyant force of tides and conservation of energy


What is the physical significance of dot & cross product of vectors? Why is division not defined for vectors?


Difference between $\Delta$, $d$ and $\delta$


If acceleration $a = v\cdot\frac{\mathrm dv}{\mathrm dx}$ , then why isn't acceleration always zero when velocity is zero?

Problems in the relation $a=v\frac{\mathrm{d}v}{\mathrm{d}x}$


What exactly is the Legendre transformation?

A mathematically illogical argument in the derivation of Hamilton's equation in Goldstein


Are stationary states always real functions?

When Eigenfunctions/Wavefunctions are real?


Physics behind rays of light in the photographs taken in the darkness

What are these rays that appear in photograph of sun?


Can unitary probability theory (quantum mechanics) emerge from a lack of information about a deterministic process?

How do we show that no hidden variable theories can replace QM?


Does the electric field of a charged particle really contribute to its mass?


How can we be sure that there are only four dimensions?

How to prove that we are living in a 3+1D world?


Can a ultracentrifuge be used to test general relativity?


Why position and momentum operators are both continuous spectrum while angular momentum is discrete?


Looking at Earth's history using a cosmic mirror

A mirror in the sky to look at past Earth


Derivation of pressure gradient stellar equation

Confusion regarding the concepts and derivation of Hydrostatic Equilibrium for a star


Are there wavefunctions that don't get more localized as we go backwards in time?

Is it possible for $\Delta x$ ($\sigma_x$) of any free particle wave packet to be decreasing at any time?


Can average acceleration be exactly determined from discrete points separated by equal time intervals?

How to approximate acceleration from a trajectory's coordinates?


What happens to a particle in a well if the well is made bigger?

Particle in infinite potential well which is doubled in size at $t_0$


Fluctuations in the value of a quantum field at a point?

Are vacuum fluctuations really happening all the time?


Mathematical Reasoning for Fluid Pressure as a Scalar


Are all the youtube animations of EM waves wrong?

Popular depictions of electromagnetic wave: is there an error?


Radioactivity and quantum superpositions


If entropy is a measure of disorder, how come mixing water and oil finishes in a well ordered, separate state?

Homemade salad dressing separates into layers after it sits for a while. Why doesn't this violate the 2nd law of thermodynamics?


According to general relativity, why are two objects at rest attracted to each other?

How does "curved space" explain gravitational attraction?


How can I calculate time dilation between our clock, and clock in satellite?

What is the correct formula for gravitational time dilation for a satellite in a circular orbit?


Why equation of motion doesn't involve derivatives of power greater than 2?

Why are there only derivatives to the first order in the Lagrangian?


Can I change the speed of light in vacuum?

Speed of light in a gravitational field?


Why does the amount of energy transferred depend on distance rather than time?


How can black holes have charge and gravitate?


Is there a way to explain quantum mechanics without invoking complex numbers?

About the complex nature of the wave function?


Does Friedmann fluid equation prove that energy of the fluid is not conserved?

Is the total energy of the universe zero?


Coefficients of Color Potential in Quarks

Is it a coincidence that quarks have exactly -1/3 or 2/3 the electron's charge?


Can Newton’s law of gravitation be derived from Coulomb’s law?

Why are so many forces explainable using inverse squares when space is three dimensional?


When a car's non-driving wheels are turned, what is the frictional force vector that actually causes the vehicle to turn in that direction?


Why isn't momentum conserved from my reference frame?

During a collision, why is momentum not conserved in a participant's frame of reference?


Are complex numbers really needed in quantum mechanics?


If I am travelling on a car at around 60 km/h, and I shine a light, does that mean that the light is travelling faster than the speed of light?


When we push a box, the box applies an opposite force on my hand, but why does my hand move with the box as I push the box if the net force of is 0?

Given Newton's third law, why are things capable of moving?


In string theory, does each string interact with all the other strings in the universe, or just the closest ones?

The Interaction between the fundamental gravitational strings


Why energy cannot be created nor destroyed if the Universe is still growing in size?


When we push a box, the box applies an opposite force on my hand, but why does my hand move with the box as I push the box if the net force of it 0?


Derivation of Euler-Lagrange equations from Newton's second law

Is there a proof from the first principle that the Lagrangian L = T - V?


On the assumption that the universe is not expanding, but things are shrinking

Is the universe expanding, or is everything in it getting smaller?


How we distinguished charges and named them so?

Why is an electron negatively charged, and what is the difference between negative and positive charges?


Can we derive the electromagnetic wave equation from $\mathcal{L}_{EM} = -\frac{1}{4} F_{\mu \nu} F^{\mu \nu} $?

Can light exist in $2+1$ or $1+1$ spacetime dimensions?


Why can't energy be below the minimum of the potential in a bound state?

Lower bound on energy is potential minimum


Why aren't Maxwell's equations overdetermined?

Do Maxwell's Equations overdetermine the electric and magnetic fields?


What's the logic behind light's following the longest path according to Fermat's Principle?

How does Fermat's principle make light choose a straight path over a short path?


Can you write and solve the EM field Lagrangian density without reference to the EM potential?

Least-action classical electrodynamics without potentials


CMS Paper of Higgs Discovery: Exclusion Plots


Demonstrate why conservation of momentum stems from invariance to translation - in Newtonian mechanics

Elementary argument for conservation laws from symmetries *without* using the Lagrangian formalism


Why is the gravitational potential energy defined as negative?


Does the Second Postulate of Special Relativity hold for non-inertial reference frames?

Does the speed of light vary in non-inertial frames?


Understanding decoherence in the double slit experiment

Practically, how does an 'observer' collapse a wave function?


Is it possible for information to be transmitted faster than light by using a rigid pole?


How do these icicles seem to defy gravity and form in my ice cube tray in my freezer?


Is there a known isotope that generates anti-matter?


How does color (or reflection in general) work?


I don't understand why escape velocity is necessary


Deriving the Coulomb force equation from the idea of photon exchange?


Where does my mass go when i lose weight?

How does mass leave the body when you lose weight?


Can some one tell me what can detect the accurate gas electric conductivity?


What Happens When A Gravitational Wave Interacts With Another One?


Why do harmonics occur when you pluck a string?


photoelectric emission with multiple photons

Photoelectric Effect, Why can't two quanta interact with an electron at the same time?


Is it possible to slow down the speed of light in a vaccum?

Can light travel slower than the maximum?


Does Dual Nature mean that any wave will have a particle counterpart?


What is the square root of the Dirac Delta Function?


Can one do the maths of physics without using $\sqrt{-1}$?


Angular Velocity About Instantaneous Axis of Rotation

Instantaneous axis of rotation and rolling cone motion


A voltmeter is connected in parallel across the load. Why?

Why are ammeters used in series and voltmeters in parallel?


When I shine laser light on a mirror, why isn't the reflected beam noisy?

Why is the light reflected at the same angle from mirror?


Why doesn't a monoatomic particle have 6 degrees of freedom?

In counting degrees of freedom of a linear molecule, why is rotation about the axis not counted?


How does the second law of thermodynamics forbid the possibility of perpetual machine of the second kind?


Accuracy of Continuous Charge Distributions

Is the electric field of a volume charge distribution well defined?


Interpretation of the energy-time uncertainty

What is $\Delta t$ in the time-energy uncertainty principle?


Physical Interpretation of Kolmogorov 5/3 law

Physical Explanation for "Kolmogorov -5/3 spectrum" in Fluid Mechanics


Can we cool a room by opening the door of a refrigerator?


How can Planck units be consistent with conflicting dimensions of mass?


Threshold frequency in photoelectric effect

Photoelectric effect, low frequency light


Is it possible to induce left-handed electromagnetic wave from positrons?

Two possible directions of the B field in relation to the E field in radio waves. How induce the left-handed direction?


Electron accelerated by gravity and electromagnetic radiation

Does a charged particle accelerating in a gravitational field radiate?


Why doesn't the Earth slowly collapse into the Sun?

Why doesn't the Moon fall onto the Earth?


How Can the Universe Be Bigger Than It is Old?


Why connect plug wires in a certain way when polarity changes in AC anyway?

Difference between live and neutral wires


Simple/elementary explanation for $\mathbf{3} \otimes \mathbf{\bar{3}} = \mathbf{8} \oplus \mathbf{1}$?

$SU(3)$ irreducible representations with tensor method


A problem of missing energy when charging a second capacitor


If I run along the aisle of a bus traveling at (almost) the speed of light, can I travel faster than the speed of light?


Why do the rail tracks seem to converge and vanish?


How do we get the image of a black hole?


Why are so many (all?) Key concepts in thermodynamics derived from a legendre transformation?

Physical meaning of Legendre transformation


Centripetal and Centrifugal acceleration/force

Do centripetal and reactive centrifugal forces cancel each other out?


Fermat's principle of least time for reflection and refraction

Why one should follow Snell's law for shortest time?


Planck's law - spectral radiance per wavelength, wikipedia article


Why isn't temperature definable for a single, classical particle?

Can a single molecule have a temperature?


Rigid body dynamics derivation from Newton's laws for higher dimensions


Can a region of space-time be viewed as a particle with properties of it's own?


How is Schrodinger's model of atom consistent with reference to Maxwell's Theory of Electromagnetic Radiation?

Why don't electrons crash into the nuclei they "orbit"?


How is the answer valid for following question?

Kinetic energy of different phases of water


Can an object tethered to a spaceship be pulled out of event horizon?

Another layman blackhole question, pulling one end of a string out from behind the event horizon


Is there any non-experimental way to determine what substances are radioactive?

Can we predict the half-lives of radioactive isotopes from theory?


Is there only one state that leads to a collection of probability distributions of observables?

Reconstruction of "wavefunction" phases from $|\psi(x)|$ and $|\tilde \psi(p)|$


Why are primordial black holes considered non-baryonic?

Are black hole regarded as baryonic matter in cosmology?


Why Cosmic Microwave Background is still present?

Will the CMB eventually recede outside our observable universe?


Why can we see the cosmic microwave background (CMB)?


How to get the Nambu-Goto action from the Polyakov action by lagrangian multiplier?

Conversion of the Polyakov action into the Nambo-Goto action?


Definite differences between special and general relativity

What is the connection between special and general relativity?


One-dimensional Schrödinger equation: reproducing a given set of energy values

In quantum mechanics, given certain energy spectrum can one generate the corresponding potential?


What is the frequency of sound emitted due to two solids colliding?

Why and how is sound produced when two objects hit each other?


In what sense does the Schrödinger equation obey the De Broglie relation?

Derivation of time-dependent Schrödinger equation from De Broglie hypothesis


Path of an object in gravitational field


A trough contains a completely immersed object. On accelerating the container upwards, which direction will the object move to?

Why does a helium filled balloon move forward in a car when the car is accelerating?


Can I get turned around backwards in time?

What would a closed timelike curve look like?


Energy stored in a capacitor vs Work that the battery does

What happens to half of the energy in a circuit with a capacitor?


Why isn’t there a $\cos(\theta)$ in the work-energy theorem?

Why is work scalar and the dot product of force and displacement?


Calculate distance of galaxy 13 billion years ago


Galaxy is 8 times closer 13 billion years ago?


How would Gauss' law hold in time varying electric fields?

Do the integral forms of Maxwell's Equations have limited applicability because of retardation?


Confusion with units of angular velocity

Simple Harmonic Motion - What are the units for $\omega_0$?


Why is the graviton spin supposed to be 2, and how can it interact with matter?

How can I read off the fact that gravity is associated with spin-2 particles from the Einstein-Hilbert action?


Relativistic Mechanics & Conservation of Energy


Can we use $F_{\rm net} = ma$ for fictitious force?

What happens to net acceleration in a non-inertial reference frame with cenripetal force?


How do I know the sign convention for $W$ and $Q$ in thermodynamics?

Which one true in First law of thermodynamics: $Q = \Delta U \pm W = \Delta U \pm p\Delta V$ or $\Delta U= \Delta Q + \Delta W $?


A plane takes off from the equator and flies due north. Is the initial tangential velocity conserved?

Does a pilot have to take into consideration the angular spin velocity of the earth?


Reversibility of the rules of classical mechanics


How does cutting a spring increase spring constant?

Is the spring constant $k$ changed when you divide a spring into parts?


Can a massless object have a charge associated with it?


Why does an overlap of atomic orbitals in a solid cause a continuous emission spectrum?

What are the various physical mechanisms for energy transfer to the photon during blackbody emission?


How does the energy gap explain the non-dissipative nature of a superconductor?

What is the link between the BCS ground state and superconductivity?


What is the Difference between $F = mg$ and law of universal gravitation?

Near Earth vs Newtonian gravitational potential


How do that charge gets transferred while rubbing?


Virtual particles and Heisenberg's uncertainty principle

What is $\Delta t$ in the time-energy uncertainty principle?


Why doesn't matter pass through other matter if atoms are 99.999% empty space?


Why is the electric field between two parallel plates uniform?

An uniformly charged infinite surface plane


Is there a contradiction with the frictional force acting on a rolling wheel on a flat surface, if you consider both the net force and the torque?

What role does static friction force play for a rolling object? How can I know what direction it points?


The observer effect, how is related to death of human brain or consciousness?

What is an observer in quantum mechanics?


Where does the energy from tidal power plants come from?


Check where am I wrong. Here is how information can be sent faster than light

Is it possible for information to be transmitted faster than light by using a rigid pole?


What force does the dynamometer show in this case?

Why I think tension should be twice the force in a tug of war


Conservation of energy in rotational motion

Where does a spinning figure skater's energy go when she slows down?


A rock connected to one end of string in circular motion gets released.. and what happens?


Does time dilation mean that faster than light travel is backwards time travel?

How does faster than light travel violate causality?


Why is the Earth not an exact sphere and what makes it bulge at the equator?

What is an intuitive explanation using forces for the equatorial bulge?


Conservation of energy when dropping a ball

Why is there conservation of kinetic energy in elastic collision and not in inelastic collision?


Do you see the outside world from inside the black hole (can you see past the horizon from inside it)?

What will the universe look like for anyone falling into a black hole?


What happens if we directly collide two equally massive black holes at near light speeds?


Calculating the tipping point of a lamp post


Quantum mechanics in terms of density operators as the fundamental object?

Is the density operator a mathematical convenience or a 'fundamental' aspect of quantum mechanics?


What is an "observer" in quantum mechanics?

What is an observer in quantum mechanics?


Why universe is so perfectly made for us?

Is the universe really "fine-tuned for life"?


Potential gravitational energy versus potential spring energy

If string is stretched just by weight, where does the gravitational potential energy goes if only half is converted to elastic potential energy?


Breaking spaghetti and conservation of energy

Why does dry spaghetti break into three pieces as opposed to only two?


In refraction how does light interact with electrons if it is not absorbed?

Does light actually travel through glass?


Is there an intuitive explanation for the Southward force caused by the Coriolis Effect on rotating spheres?


Why can't our cognitive sense or five senses sense or fathom hyper-dimensional spaces?

Why are we not able to visualize Dimensions beyond 3 (or maximum 4 including time)?


Can change in kinetic energy be negative?


Does the centre of mass of a circular object such as a cylinder or sphere rotate?

Why does an unhinged body rotate about its centre of mass?


Noether's Theorem for Non-Rigid Transformation


Gravitational potential at the centre of Earth


Differential form of Gauss's law from Coulomb's law in spherical coordinates

Divergence of $\frac{ \hat {\bf r}}{r^2} \equiv \frac{{\bf r}}{r^3}$, what is the 'paradox'?


Can something without mass exert a force?


How is the fabric of space-time curved? It bends due to energy or mass, but what causes bending?

Better explanation of the common general relativity illustration (stretched sheet of fabric)


Difference between Mixed and Pure states

Which experiment can differentiate a statistical mixture from a superposition state?


Why can we set $c$ and $\hbar$ to 1 when it changes the result?

What exactly are we doing when we set $c=1$?


Why does nature have higher atomic nuclei if Iron(Fe) has higher binding energy per nucleon?

Why do elements on the Binding Energy per Nuclear Molecule after Iron (most stable) even form?


How does a battery create potential difference?

How is a potential difference created between two points?


Can you create high-energy photons using multiple low-energy photons?

Is it possible to combine two photons of different energies to get a single photon of a higher (combined) energy?


References on De Broglie-Bohm pilot wave theory


Lorentz elements of inverse transformation

Pure Lorentz boost; transpose $\neq$ inverse?


Question on eigenstates of hermitian operators that fulfill canonical commutation relation

Trace of a commutator is zero - but what about the commutator of $x$ and $p$?


Discreteness of the general angular momentum in quantum mechanics


Is Purity monotonically decreasing with increasing Von Neumann entropy?

What is the relation between linear purity and von Neumann entropy of a state?


What is the direction of the frictional force acting on a rolling wheel?

Why doesn't friction accelerate a ball undergoing rolling?


Why does the speed of light in vacuum never change?

Do we know why there is a speed limit in our universe?


Ask about the Website or Books about physics from A-Z


Force and velocity $-$ are they simultaneous?

Are acceleration and velocity simultaneous?


Why is silver the best conductor of electricity?


Suppose you are in a closed box which is in motion

Can we really not tell if we are moving?


Why is the work done by a rocket engine greater at higher speeds?


Are there gaps present between lines in a continous line spectrum?

Is the electromagnetic spectrum discrete?


If the photon is the force-carrier for the electromagnetic force, how does the electric charge of a black hole escape the event horizon?

Detection of the Electric Charge of a Black Hole


I have a container completely filled with water, I add copper coins, how much can the water level rise before it spills?

How far can water rise above the edge of a glass?


I can't prove the Archimedes' principle in a particular case

How does the buoyant force on a cube at the bottom of a tank of water manifest itself?


Why does kinetic energy increase quadratically, not linearly, with speed?


How does a one-sided glass work on atomic level?


Do wormholes have mass that depends on the spacial separation, the temporal separation, the relative motion of the two ends of the wormhole


Why are velocity and kinetic energy not proportional?


Runge Kutta 4 for orbits and Newtonian Mechanics


Textbook recommendation for computational physics


If I throw a ball at a black hole, will the ball exceed the speed of light when it reaches the event horizon?

Will free-fall object into black hole exceed speed of light $c$ before hitting black hole surface?


How does reflection work at a quantum level?

Explain reflection laws at the atomic level


Is it possible to have no pressure gradient in a tank?

Can there be a pressure gradient in a large enough closed container?


Where does the postulate of quantum mechanic that possible results are eigenvalues come from?


What happens when a long-wavelength photon "hits" a small black hole?

Can a black hole absorb photons whose wavelengths are greater than the BH horizon size?


Gravitational Time Dilation and Speed of Light

GR. Einstein's 1911 Paper: On the Influence of Gravitation on the Propagation of Light


Why the force exerted by a fluid on an object submerged in it is always perpendicular to it's surface?


What if we take jerk (i.e. the rate of change of acceleration) in Mechanics?

Is it possible to have a rate of change of acceleration?


Validity of naively computing the de Broglie wavelength of a macroscopic object


Does the photon decay due to loss of energy in a gravitational shock wave that it creates?

How does the propagation of gravity work for photons?


Why 2 electrons can't be in the same quantum state when they are distant apart?

Does the Pauli exclusion principle instantaneously affect distant electrons?


Why is the Carnot engine the most efficient?


Chaining together two successive time dilations through two Lorentz transformations

Relativistic velocity addition from time dilation


Falling Speed of earth towards an object?

Don't heavier objects actually fall faster because they exert their own gravity?


How does instantaneous velocity or acceleration have any other numerical value than 0?


Tension in a string attached to different masses

Why is tension in a rope the same at every point?


Why can't we accept that there's no black hole?

Can black holes form in a finite amount of time?


Which are the best mathematical methods books for which topic for a physics undergrad?


why are there no atoms with a few protons but many more neutrons?

What makes the number of neutrons the number of proton similar?


If F(action) =F(reaction), why doesn't a ball bounce to its original height?

Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground?


What is the algorithm for finding the constraint force using the method of Lagrange multipliers?

How are constraint forces represented in Lagrangian mechanics?


How can standing waves be produced in an open organ pipe if the ends are open?


Unpolarized light - Why don't light sources then look invisible?


Second book on QFT before understanding Conformal Field Theory

Reading list and book recommendation on Conformal Field Theory


Is Bernoulli's equation the correct explanation of a curved soccer ball?


Is external force equal to restoring force

If string is stretched just by weight, where does the gravitational potential energy goes if only half is converted to elastic potential energy?


Speed of light dependent on source velocity in other medium

Does the speed of medium affect the path of light?


Does time dialation cancellation occur between two observers moving in opposite directions


How do we quantify and measure the net entropy of today's universe?

What is the entropy of the universe today?


Book recommendations : Classical Mechanics

Which Mechanics book is the best for beginner in math major?


Why are we not able to visualize Dimensions beyond 3 (or maximum 4 including time)?


What is the QFT state with two distinguishable fermions present?

Fermions, different species and (anti-)commutation rules


What equations of general relativity and quantum mechanics are we trying to unify?

A list of inconveniences between quantum mechanics and (general) relativity?


What is the physical meaning of a dot product and a cross product of vectors?


How can microwave radiation penetrate through walls but visible light cannot?

How can wifi penetrate through walls when visible light can't?


Challenging and "serious" introduction to basic physics


Deriving Canonical Transformation from Generating Function using Principle of Stationary Action

Boundary conditions for calculus of variations in phase space and under canonical transformations


Difference in the direction of propagation of em wave

How to determine the direction of a wave propagation?


Electrostatic field-Field lines relationship

Why does the density of electric field lines make sense, if there is a field line through every point?


Why doesn't there exist a wave function for a photon whereas it exists for an electron?


Transformation connecting two representations - Quantum mechanics

How does the momentum operator act on state kets?


Is Universal Law of Gravitation a 'law'?


Can the heat given to a thermodynamic system decrease the temperature of the system,I.e. specific heat capacity can be negative

Are there any known negative heat capacities?


Why is the moon in free fall? Isn't there a centrifugal force acting on it?

What provides the centrifugal force for planets orbiting a star?


Can the speed of light in vacuum depend on the acceleration of the frame of reference?


Exercise on gauge invariance and global and local symmetry

Exercise on local and global symmetry for a given Lagrangian density


Will an iron sphere covered all over with little neodymium magnets become a magnet monopole?

Why are magnets in form of hollow sphere not a magnetic monopole?


Lagrangian of a free particle, from Landau mechanics page 6

Trouble understanding Landau & Lifshitz writing about Lagrangians and Galilean Relativity


Does superluminal travel imply travelling back in time?


Can we theoretically prove that for an elementary particle to carry a nonzero charge it must have a nonzero mass?


Raising and lowering indices: is it a convention?

Why do we select the metric tensor for raising and lowering indices?


Can relative permittivity be less than 1?


What is a complete book for introductory quantum field theory?


Are gravitational waves subject to gravitational lensing?

Do gravitational lenses work on gravitational waves?


Griffiths on Averaging and the Macroscopic Electric Field


Why do motorcycles front wheels lift of the ground when accelerating quickly


How would neutron matter appear to the naked eye?


What is the physical significance of the off-diagonal moment of inertia matrix elements?


Why can't $ i\hbar\frac{\partial}{\partial t}$ be considered the Hamiltonian operator?


Does it make a difference if we treat the wavefunction as having two real components instead of one real and one imaginary component?


Textbook to understand special/general relativity


Travelling 3.6 LY at $(3/4) c$, how much time passes for the traveler and how much time passes for the people in Alpha Centauri?

How long would it take me to travel to a distant star?


Reasoning behind $\delta \dot q = \frac{d}{dt} \delta q$ in deriving E-L equations

Least action principle : is $ \delta \frac{dx}{dt} = \frac{d \delta x}{dt} $ always true?


How do someone calculate the wavelength of a receding object in space?

How is Doppler redshift of distant galaxies established?


Is energy conserved in an expanding universe?

Is the total energy of the universe zero?


Why does pair production of an electron and positron only needs 1 photon whereas their annihilation releases 2 photons?

Why during annihilation of an electron and positron 2 gamma rays are produced instead of 1?


How is the angular momentum conserved in this case?

Shouldn't ball has to move in the circle even after cutting the rope by which it was attached?


Does conservation of energy hold in quantum mechanics?

Energy conservation and quantum measurement


How can magnets be used to pick up pieces of metal when the force from a magnetic field does no work?


Problem/Exercise: Schrödinger's cat (QM)

Coherent states of the form $|{-\alpha}\rangle$


Can linear momentum be conserved before and after collision in the presence of an external force?


What does it mean be gravity propagates with $c$?


What is the purpose of a combustion chamber in a jet engine?


Air velocity flowing out of a pierced can

Calculate flow rate of air through a pressurized hole


Why not free electrons in atom doesn't radiates em waves\photons?

Why don't electrons crash into the nuclei they "orbit"?


What is spin as it relates to subatomic particles?


Can a third type of electrical charge exist?


Why does a the addition of a total derivative to the Lagrangian leave the equations of motion invariant?

Does a four-divergence extra term in a Lagrangian density matter to the field equations?


Can a photon be called a disturbance in the electromagnetic field?

Do photons truly exist in a physical sense or are they just a useful concept like $i = \sqrt{-1}$?


Why do capacitors in a dielectric have the same charge as without the dielectric


The Field $\mathbb{F}$ of A Hilbert Space


Force on a crash test dummy during a crumple zone experiment

Calculate impact force when time is not mentioned


A problem of missing energy when charging a second capacitor


Would someone versed in relative motion consider it more accurate to say that a car slammed into, or collided with, a wall?


What is the weight equation through general relativity?


Why dont we account the rotation of the earth in aircrafts? Is it just because of the air or is there more to it?

Does the rotation of the earth dramatically affect airplane flight time?


What is the maximum force you can exert on the ground with one leg?

Can you ever exert more downwards force than your weight?


Physical mechanism by which the body removes weight during long-term human weight loss

How does mass leave the body when you lose weight?


Why is the image of a laser point both real and virtual when shone on a plane mirror?


Why is sound produced when we hit a metal?

Why and how is sound produced when two objects hit each other?


Why would Antimatter behave differently via Gravity?


Why do we use Hermitian operators in QM?


Tension in a stone, string system undergoing uniform circular motion

Why does a string remain taut in circular motion


Would you reach a singularity before evaporation of the black hole?

Does any particle ever reach any singularity inside the black hole?


Confused why momentum is conserved in 2 falling bodies problem


Quantum Field Theory literature - rigorous and clean

A No-Nonsense Introduction to Quantum Field Theory


Why does holding something up cost energy while no work is being done?


Why dont microwaves pass through the microwave door

How does the grid on the microwave oven window prevent microwave radiation from coming out?


Effective refractive index and refractive index


How to evaluate the Euler-Lagrange equation for the electromagnetic Lagrangian?

Euler-Lagrange equation in curved spacetime: how to calculate $\partial \mathcal{L}/\partial(\nabla_\nu A_\mu)$?


What is the difference between Minkowski Space and Flat Metric?

How to prove that a flat spacetime admits Minkowski coordinates?


Hello I was trying to derive wave equation? Can anyone tell me why we calculate curl of curl of electric field and what it signifies?

Why do we calculate the curl of curl of the electric field and what does it mean physically?


Is there a $t$-channel process for $q\bar{q} \rightarrow gg$?

What is the Mediator in this Feynman Diagram $q\bar{q} \rightarrow gg$?


Why must normalisable eigenfunctions have $E > V_{min}$?

Lower bound on energy is potential minimum


Why do people say we need general relativity in order to explain why light is affected by gravity?


On-shell and off-shell transformations in Noether's theorem


Difficult in understanding question of minimum stopping distance

Not able to understand the meaning of question?


Is there any way to measure the one-way speed of light?


Symmetry factor for Feynman diagram in scalar field theory

Computing symmetry/combinatorial factor for a diagram in $\phi^4$ theory


Does Loop Quantum Gravity predict general relativity in semi-classical Limit?


Do Virtual Photons Travel with the Speed of Light?

Are virtual particles limited by the speed of light?


Are vacuum fluctuations really happening all the time?


Does repulsive or opposite gravitational force exist?

Is anti-gravity (i.e. repulsive gravity) possible in theoretical physics?


I was learning SHM and I came across equation $k = mw^2$

Why does $k/m=\omega^2$ for harmonic motion?


What are Uncertainties in Quantum Mechanics intuitively?


How to compute the self-energy of a sphere? Electrostatics

Self-energy of a uniformly charged, non-conducting sphere, using energy density formula


When we define the S-matrix, what are "in" and "out" states?


Why exactly is reality 3 spatial dimensional?

Why does the universe exhibit three large-scale spatial dimensions?


Given Newton's third law, why are things capable of moving?


Is a black hole singularity a single point?


How is the classical twin paradox resolved?


What is the relation of differential geometry to General Relativity and Quantum Field Theory?


What is $C_\mathrm{eq}$ for this circuit?


Why Are the Laws of Physics the Way They Are?

Why can mathematical equations describe this world?


Number of emitted electrons by photoelectric effect

Photoelectric effect in a a frequency range


Why are formulas of rotational dynamics always having cross product?


If spacetime itself is expanding, how could we ever tell?


How do many conservative forces come together to make a non-conservative one?


Cantilever beam with a mass at different positions and resonance frequency

Resonance Frequency and Centre of Gravity


Equal, opposite forces in Newton's third law


Why do we experience more centripetal force when we make a sharp turn compared to a wide turn?

How is centripetal force related to radius?


Gauge invariance and the degrees of freedom

Counting the number of propagating degrees of freedom in Lorenz Gauge Electrodynamics


Inconsistency regarding Archimedes' Principle


What is the typical order of magnitude (*numerical* in $\rm Hz$, not expression) of frequency of a gravitation wave?


Is Ricci's theorem can be simply deduced using covariant derivatives of fundamental tensors?

Why is the covariant derivative of the metric tensor zero?


What kind of information does light carry so that brain can "see" shapes and distances of objects?

How does the human eye knows how far the object from which the photon was reflected?


What is the meaning of the structure constant for the $\rm SU(3)$ group and how I can find its values?

How do I find the values for the structure constants ($f^{abc}$) of a gauge group?


How do you distinguish between two spacetime metrics?

Coordinates vs. Geometries: How can we know two coordinate systems describe the same geometry?


How to explain visually and in a mathematically simple manner why the moment of inertia of a system is minimum at its center of mass?

Meaning of parallel axis theorem: why is the moment of inertia minimum if the axis passes through the CM?


What is the molecular explanation of a common tension in an ideal rope even when two unequal forces are applied at the two ends of the rope?


The unique form of the Lagrange equation in all coordinate system. Any proof for it?

Covariance of Euler-Lagrange equations under change of generalized coordinates


Where does the electron come from when a free neutron transforms?


Resources to consult alongside Griffiths?

Recommended books for advanced undergraduate electrodynamics


If photon experiences time in an instant, does it mean that it's predestined to be consumed?

How does a photon experience space and time?


Reference frame for massless particles like light

Does a photon in vacuum have a rest frame?


Electrical potential energy stored in vacumm for a single point charge?


How can I make sense of the way (screen) colors are generated?

Colors from a computer vs. colors from visible spectrum of sunlight


Why should voltmeter have infinite resistance?

Why should a voltmeter have a higher resistance than of any circuit element across which the voltmeter is connected?


${}$Can the gravitational constant $G$ be calculated theoretically?


Why can visible light go through green-house gases?

How does carbon dioxide or water vapour absorb thermal infra red radiation from the sun?


What are the necessary conditions for a CFT to have a holographic dual?


What is pressure at microscopic level in a liquid? how can I imagine it?

Microscopic interpretation of pressure in liquids


How did people estimate the speed of light before modern technology?

How did Rømer measure the speed of light by observing Jupiter's moons, centuries ago?


What does the notation $\mathcal{O}\left(\frac{1}{r^2}\right)$ mean?

What does the term $\mathcal O(\epsilon^2)$ mean?


Why is there no absolute maximum temperature?


Weyl anomaly in 2d CFT (string theory lectures by D.Tong)


how to create a kinetic energy kugelblitz in theory?

If a mass moves close to the speed of light, does it turn into a black hole?


Conflict of domain and endpoints in Noether's theorem and energy conservation

Why is the symmetry variation $\delta_s q$ different from the ordinary variation $\delta q$?


Does the fabric of spacetime go through objects?

Better explanation of the common general relativity illustration (stretched sheet of fabric)


Derivation of the Force Law predicted by General Relativity

What is the weight equation through general relativity?


Magnetic field and magnetic field intensity and magnetisation intensity ($B$, $H$, $I$)

What's the difference between magnetic fields $H$ and $B$?


Which bulb will light up first in a series circuit?

In what order would light bulbs in series light up when you close a long circuit?


Can we define the effective mass or the moving mass of a photon?


Why is a Coulomb the charge of $6.24 \times 10^{18}$ electrons?


Is Schwarzschild's solution in his original paper consistent with current solutions?

$r$ and $R$ difference with Schwarzschild metric


How does radiation from a nuclear accident "infect" clothing and people?

How does an ordinary object become radioactive?


Derivation of Conservation of Energy from Newton's Second Law

Prove the Total Mechanical Energy of the System is Conserved via Differential Equations


Why does the reflected light have a specific direction?

Why is angle of incidence equal to angle of reflection?


How to know if something is a primitive concept, a law, a definition or a theorem


How do we know that the idea of entropy is true?

How do you prove the second law of thermodynamics from statistical mechanics?


Momentum conservation in vertical direction. Confusion

Can linear momentum be conserved before and after collision in the presence of an external force?


Why current in series circuit is the same?


What's the best classical physics (mechanics, electromagnetism, etc) textbook to read as a regular book?


Does a hot object in space/vacuum gets cold? how?

Why does the blackbody radiate even at thermal equilibrium?


What exactly is "pressure", and what's its relation to force?


Infinite Series vs Integral Representation of State Vectors in QM?

Expansion coefficients of an arbitrary state in the Hilbert space of one-particle states


If I am travelling on a car at around 60 km/h, and I shine a light, does that mean that the light is travelling faster than the speed of light?


Why is oil called more viscous than water when we slip on oil more than we do on water

Why is oil a better lubricant than water?


Reading list and book recommendation on Conformal Field Theory


Does the weight on a car's wheels decrease with increasing speeds?

Why do cars gain lift while going at a high speed?


Can an atom be split and put back together?


Can we measure renormalized mass in QFT?


In an anti-matter universe, would an anti-matter black hole emit anti-matter gamma radiation?


How can a 13 year old kid like me learn quantum mechanics and other advanced physics topics?

What's the standard "roadmap" to learning quantum physics?


Looking for an understanding of Toroidal Moments

Are neutrinos affected by electromagnetic forces?


How to write $3\otimes3\otimes 3=10\oplus8\oplus8\oplus1$ in a tensorial way?

$SU(3)$ irreducible representations with tensor method


What actually causes blackbody radiation?

What are the various physical mechanisms for energy transfer to the photon during blackbody emission?


Doubts in understanding the instantaneous velocity


How does the Hamiltonian change if $L\to L + \frac{dF}{dt}$?

Invariance of canonical Hamiltonian equation when adding the total time derivative of a function of $q_i$ and $t$ to the Lagrangian


How is Gauss' Law (integral form) arrived at from Coulomb's Law, and how is the differential form arrived at from that?


Is there any model explaining why would a particle revolve around another one in an elliptical orbit?


Naive question about particles and spinor fields

What does it mean that particles are the quanta of fields?


Why do external observers see LIGO results if an object falling into a black hole never reaches the event horizon?

So Black Holes Actually Merge! In 1/5th of a Second - How?


Does work function of a metal plate depend on its net charge?


Elastic collision between a circle and a point


Is curved spacetime a real thing or just math?


Point-like particle vs naked singularity?

what is the difference between a blackhole and a point particle


How can magnets be used to pick up pieces of metal when the force from a magnetic field does no work?


Conformal invariance for infinitesimal transformations

Topological/Geometrical justification for $\text{CFT}_2$ being special


Why isn't there an atom with an electron at the center and a proton on the outside?


How are we supposed to derive formula for magnetic field density?

Magnetostatic energy density -- derivation without introducing inductance?


Continuity equation for a charged particle

Continuity equation for charge and current densities of an accelerated point charge


Newtonian Mechanics Thought Experiment Gone Wrong And Needs Clarification

Given Newton's third law, why are things capable of moving?


How do they calculate the distance merging massive bodies are away from earth using just the gravitational waves?


What's the difference between electromotive force and Electrical potential?

What is the difference between electric potential, potential difference (PD), voltage and electromotive force (EMF)?


Interaction in the linear schrödinger equation


"Doing the same thing over and over and expecting different outcomes is the definition of insanity" - ( Albert Einstein,) and quantum mechanics

What is the reason that Quantum Mechanics is random?


How to get Bohr model from Schroedinger equation?

How is Bohr's model related to electron cloud models via the correspondence principle?


Which references should I use for the following topics in Waves and Optics?


What is the Coandă effect? How is it defined, and what causes it?


If gravity is a pseudoforce in general relativity, then why is a graviton necessary?


What represents the state of a quantum system?

Are states of a quantum system represented by vectors in a Hilbert space?


Hypothetical: Can I determinate if my room is moving by measuring the time it takes for a photon to reach the oposite wall?

Can we really not tell if we are moving?


If a photon truly goes through both slits, then why can't it make two dots (excite two atoms) in the screen?


In substances where light is slowed down, is its momentum lessened and if so, how does it speed up again when emerging from that substance?

Does light loses its energy when it passes through denser medium?


Is it necessary that if we concider a system then always work done by internal forces would be equal to zero?


How to make sense of a photon time and space being dilated infinitely?

How does a photon experience space and time?


Direct experimental proof of relativity of simultaneity

Has relativity of simultaneity been directly observed?


How does a pinhole aperture convert incoherent monochromatic light into coherent light?

How coherent light is created for single slit experiment?


Is the linear combination of stationary states exhaustive?

Proof for the completeness of eigenfunctions of a self-adjoint operator


Why isn't the symmetric twin paradox a paradox?


Given Newton's third law, why are things capable of moving?


Gravity bends space, so how can space have only 3 dimensions?

Better explanation of the common general relativity illustration (stretched sheet of fabric)


Expansion of space or contracting of matter?

If spacetime itself is expanding, how could we ever tell?


Would an astronaut, alone in space with no reference point, get dizzy?

How does an isolated body in deep space 'know' it's rotating?


Why complex numbers are used in electronics?

What's the physical meaning of the imaginary component of impedance?


Physical interpretation of $\frac{\partial \rho}{\partial t} + \frac{\partial j}{\partial x}=0$


Why holes in a semiconductor are associated with a net positive charge?

Are holes a fundamental particle? Are they a real thing or just a construct?


Potential energy between attracting molecules

Why does it make any physical sense for a body to have negative potential energy?


What happens to radians in this calculation?

Are units of angle really dimensionless?


Advantages of using different metric signatures in relativity and QFT


Generalised basis independent relationship between Von Neumann Entropy and Purity of a quantum state

What is the relation between linear purity and von Neumann entropy of a state?


Why doesn't a fly in the moving train hit the wall?


How both inertial frames of reference are valid when it comes to time dilation?

How is the classical twin paradox resolved?


Why the cross product of two vectors gives a vector in an orthogonal direction?


How do we know that the universe is really fine-tuned?


Where can I find an online General Relativity course(s)?


How do we know that entangled entities can retain their connection and knowledge of their counterpart irrespective of the distance between them?

Why is quantum entanglement considered to be an active link between particles?


Is every fundamental force a bend or a wave in some kind of field?

Geometric interpretation of Electromagnetism


Can you help me understand how constraints are mathematically expressed?


How can a singularity in a black hole rotate if it's just a point?


If string is stretched just by weight, where does the gravitational potential energy goes if only half is converted to elastic potential energy?


Do entangled particles really exchange information?


Conservation of energy when slowing an object down