Why is gravitation force always attractive?


de Broglie relations: calculate wavelength using two different approaches


Why don't spinning tops fall over?


Why does it seem like a broken magnet's poles flip?


Is spacetime simply connected?


How fast does force propagate through matter?


The meaning of imaginary time


Why is a cycloid path the fastest way to roll a ball downward?


Projectile with air resistance


Can I measure a journey time < 100 years on a 100 light year voyage?


Is anti-matter matter going backwards in time?


How many physical degrees of freedom does the $\mathrm{SU(N)}$ Yang-Mills theory have?


exercise books for Feynman diagrams


General relativity, gravity and spacetime curvature


Was the mass of the universe the same when it first began as it is now?


Why is travelling around the speed of light a problem?


I read a book saying bernoulli's flight equations didn't have as much impact on lift as most people think


Why don't we see solar and lunar eclipses often?


How can we deduce the relation $m = \frac{m_0}{\sqrt{1-\frac{v^2}{c^2}}}$ between relativistic mass and rest mass in special relativity?


Are there formulae for calculating stellar luminosity and effective temperature as a function of age?


Why can we skate on ice?


What is the Physical Meaning of Commutation of Two Operators?


If I'm floating in space and I turn on a flashlight, will I accelerate?


String Theory- Are strings the end? What are they made of?


Reading the Feynman lectures in 2012


Can 'Backradiation' warm its own source?


Is time slowing down and disappearing from the universe instead of the expansion of universe?


The universe could have created itself?


Does light color change when refracting?


Why are people weightless whilst in orbit around the Earth? ISS? Satellites?


Einstein's postulates <==> Minkowski space. In layman's terms


Water Displacement in the Oceans As a result of Global Warming


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


current in wire + special relativity = magnetism


Geodesic for Electromagnetic forces


Are continuous mathematical models of discrete physical phenomena messy because of a disconnect between “continuous” and “discontinuous”?


Why does time reversibility imply equilibrium in a thermodynamic system?


Would Beetee's electrocution plan work and kill the tributes in the lake?


If time standard clocks and any memories about the time standard are destroyed, can we recover the time standard again?


Do current models of particle physics explain the chemical properties of elements/compounds?


Canonical everyday-life example of a technology that could not work without humans mastering QM in analogy to the application of GR in GPS?


Maximum limit on the number of paper-folds possible after tearing into halves


ALL "forces" as manifestations of properties of space-time


Elastic Collision Between Two Objects


Can mass be totally converted into energy?


A No-Nonsense Introduction to Quantum Field Theory


Mechanics around a rail tank wagon


Newton and the change of mass with time


gravitational lensing


What would happen if I was in the centre of the Earth?


Did space and time exist before the Big Bang?


Does trade affect Earth's rotation?


How can anything ever fall into a black hole as seen from an outside observer?


Why does the speed of light $c$ have the value it does?


The potential and the intensity of the gravitational field in the axis of a circular plate


What formula connects the moment of inertia and angular velocity?


Expanding universe and the speed of light


Dumbed-down explanation how scientists know the number of atoms in the universe?


A flying fly inside a sealed box on a scale


Train crash: are these situations alike?


Photon energy - momentum in matter


Why does dust stick to rotating fan propeller?


Do Hydrinos Exist?


What is the universe 'expanding' into?


Force applied on the ground


Is it possible to speed up radioactive decay rates?


Geocentric Model in General Relativity


Is it possible to create matter?


How does a treadmill incline mechanism work?


How Can There Be Magnetic Force Without Velocity


How can a proton be converted to a neutron via positron emission and yet gain mass?


What exactly is the 'observer' in physics and/or quantum mechanics?


how does an electric field comes inside a conducting wire inside the circuit?


What is the proof that the universal constants ($G$, $\hbar$, $\ldots$) are really constant in time and space?


What exists in the Space between atoms


How does electron move around nucleus?


Is it possible to generate usable electricity from the motion or magnetic field of the Earth?


When Physicists thought neutrinos were faster than the speed of light


Why two balls of different mass dropped from the same height falls the ground at the same time?


On becoming theoretical physicist


Different perspective in Quantum mechanics


Why isn't temperature measured in Joules?


Why is it that using cell phone can invite lighting strike?


Does gravity weaken by the square of the distance because the energy is dispersed over the square of the distance


If 'pure energy' is photons, and energy is conserved, how can matter and antimatter (electrons and positrons) annihilate into photons and vice-versa?


Helpful tutorials on force


Applications of low-dimensional topology to physics


Intuitive understanding of centripetal vs. centrifugal force


Experimental proof of the principle of superposition in QM


Software for geometrical optics


Is there a good chance that gravitational waves will be detected in the next years?


Because position is relative, is it possible to see a star orbiting a planet?


How is traveling back in time possible in theory according to some scientists?


Why does the moon look bigger at the horizon?


Could Dark Matter form black hole?


Are there any applications of elementary number theory to science?


Space expanding, or light slowing down?


What's the most efficient way to study physics?


Effects of magnetic fields on our bodies


Phase shift of 180 degrees on reflection from optically denser medium


Does the time for communication between moving objects solely account for each object to perceive the other object's clock to more slowly tick?


Why are snowflakes symmetrical?


How functions become operators in quantum mechanics?


Relativity's effects on centripetal motion


Optics of a rotated spectacle lens


Speed greater than light in circular motion


What allows the modified Urca process to work at lower density than direct Urca in neutron star cooling?


Where do electrons get their ever-lasting circulating energy?


Universal speed limit


quantum mechanics and canonical conjugate


If Earth Were Filled with a Compressible Fluid and Spun Really Fast, What Hollow Would Form?


Energy needed to raise energy level of an atom?


How do gravitons and curved space time work together?


Calculate analytically the time until two spheres meet due to gravitation


How do you calculate power at the focal point of a mirror?


Flushing water-Is it related to Coriolis force?


How can a single slit diffraction produce an interference pattern?


Why is pressure always non directional?


Why is the camera not the culprit?


Resource for nonphysicists about QM/GR incompatibility


Can the laws of classical mechanics be derived from quantum mechanics?


How does a black hole slow time?


How do you change Planck's law from frequency to wavelength?


What does "the ${\bf N}$ of a group" mean?


Variational Calculus or Tensor Calculus?


Cubic symmetry and a stiffness tensor


What does it mean that the universe is "infinite"?


Why does calculus of variations work?


Help explain how direction change relates to acceleration


Is gravitational acceleration less affected by relativistic mass increase?


"Troll physics": Buoyancy for infinite power


What is the Earth truly rotating about/revolving around?


Question Based On Units And Measurements Involving Lengths


Gravity propagation speed


Photon speed going from $0$ to $c$ initially?


Why doesn't our body gets crushed due to the atmospheric pressure?


Two explanations of non-zero atomic radius


Why doesn't the Moon fall upon Earth?


As the earth rotates around itself, does this have any effect on the dynamics of flights?


Why do they store gold bars with the narrow side down?


Electricity directly from heating a material


Do black holes exist?


How can momentum but not energy be conserved in an inelastic collision?


Books for Condensed Matter Physics


How can you calculate how fast a spinning ring/cylinder will accelerate a mass via gravitomagnetism?


Physics breakthroughs in the last two decades


Red color has largest wavelenght and violet minimum (in the range of visible light). then why does violet light appears reddish? RED + BLUE = VIOLET


Wave theory limit of geometric optics?


What's the difference between electron movement and charge movement in electricity?


Why do electrons and protons attract each other?


Good Books on Gauge Theory


Time dilation at a black hole


Entanglement in time


Nuclear structure


What do we mean by electromagnetic charge?


Constants of infinity


Dark Energy / Accelerating universe: naive question


Half-Life Question


Why do we say that light travels at a speed?


Is apparent horizon curvature lesser due to refraction of light in the atmosphere?


When lasers are used to cool atoms or ions, etc where does the heat go?


Is the Pauli exclusion principle as Brian Cox described it?


How can we be sure that nature isn't "faking" quantum statistics?


Physics textbook for mathematicians


Has the black hole information loss paradox been settled?


Why is the Ampere a base unit and not the Coulomb?


Man on a rope task


Doppler Shift when Light Travels Through Two Different Mediums


Photometer: measured Irradiance L converted to photon rate


Why must a singularity form inside a black hole?


Do two beams of light attract each other in general theory of relativity?


Apparent paradox in equation of continuity


Magnifying Glass-How does it work?


Does mass affect speed of orbit at a certain distance?


Exact Solutions to the Navier-Stokes Equations


Is the Lorentz force conservative?


Why is there still radiation left from the Big Bang now?


How can black holes have gravity?


Proof of Spin-statistics theorem


Question about two masses connected by a spring


Why two objects get charged by rubbing?


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


Is the Higgs particle the final one predicted by the Standard Model?


How vacuous is intergalactic space?


Conveyor scales modeling


Ascertain the height an object has fallen from given force exerted and mass


Why do cosmic bodies revolve?


Why does a motor draw more current stopped or under load?


QFT as a rigorous mathematical theory


What is the variable plotted on the y-axis on these Higgs exclusion graphs?


What is the difference between implicit and explicit time dependence e.g. $\frac{\partial \rho}{\partial t}$ and $\frac{d \rho} {dt}$?


Multiple measurements of the same quantity - combining uncertainties


Negative chemical potential


Which is easier, pushing or pulling?


Choice and identification of vacuums in AdS/CFT


The collision of Phobos


Atoms: boson or fermion?


Can a particle be *physically* observed inside a quantum barrier?


Physical meaning of force times area


How to find orbital radius of star in a binary system using redshift and orbital period data?


Noticing that Newtonian gravity and electrostatics are equivalent, is there also a relationship between the general relativity and electrodynamics?


How are the definitions of a coherent state equivalent?


What experiments prove the greenhouse effect?


Why does adding solutes to pure water lower the the specific heat?


What are "electron holes" in semiconductors?


Are galactic stars spiraling inwards?


Different factors of $4\pi$ and $\epsilon_0$ in Poisson equation


Book covering Topology required for physics and applications


Experimental evidence for parallel universes


What would an observer see if he/she flew toward a clock at relativistic speeds?


Accelerating electrons via microwaves


Why fundamentally does classical mechanics lead to second order dynamics?


Why do current and electrons flow in opposite directions?


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


Proof of conservation of energy?


What software programs are used to draw physics diagrams, and what are their relative merits?


Chance of objects going against greater entropy?


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


What happens to an embedded magnetic field when a black hole is formed from rotating charged dust?


Woodwind instruments overtones


Quick introduction to electromagnetism / Maxwell's equations


Can we calculate the frame dragging force of the Earth?


Why $\vec F=m\vec a$ instead of $\vec F=m\vec v$?


What state is fire? Solid, Liquid or Gas or Plasma?


Study Quantum Physics


How does Annihilation work?


Density operators in a Hilbert Space


Homework about spinning top


About the Ether Theory acceptance


Does photon have size measurement because of its particle nature


Why would Antimatter behave differently via Gravity?


Physics needed to build a top down billiards game


minimum possible absolute temperature in the universe?


What is the "Event Horizon" of a black hole


What is the physical significane of Complex Time Evolution in EM Waves?


Why does dilation invariance often imply proper conformal invariance?


Which Optics textbooks are good?


What point of application of force ensures more acceleration in a rod?


If the earth left the solar system for interstellar space. How long would it take for atmosphere to freeze


Quantum Mechanics and Direction of time


Is there an upper limit to a rocket's size/payload?


Disk spinning at the speed of light


Why photon has a wave nature?


In an absence of gravity, does time flow faster or slower than on Earth?


Balloons and lifting gases


Is spacetime all that exists?


Why shouldn't the uncertainty principle be interpreted as an observer effect?


The sound when boiling water


Why are coordinates and velocities sufficient to completely determine the state and determine the subsequent motion of a mechanical system?


Neutrino unaffected by gravity


What constitutes an observation/measurement in QM?


History of interpretation of Newton's first law


Will the moon really escape the Earth?


Non-Degeneracy of Eigenvalues of Number Operator for Simple Harmonic Oscillator


What combinations of realism, non-locality, and contextuality are ruled out in quantum theory?


Learning more about String theory


What is the relation between electromagnetic wave and photon?


How do I calculate the (apparent) gravitational pull with General Relativity?


Is there a proof of existence of time?


Is there anything smaller than a quark?


Special Relativity Textbooks Request


Good and simple reference for studying about ADM mass


Intuitively, what is the source term of the Einstein field equation?


What do physicists mean when they say "speed of light"?


Electromagnet emitting light


If photons can be absorbed by electrons, wouldn't that mean light has a charge?


When do I apply Significant figures in physics calculations?


What is the symmetry which is responsible for preservation/conservation of electrical charges?


Is there a way to save electricity from lightning?


What is the meaning of speed of light $c$ in $E=mc^2$?


Why is light produced when an underwater bubble is collapsed with a sound wave?


Why magnetic field generates around current carrying wire?


Why is the sky not purple?


Air flow coming out of a fan feels much stronger than air flow coming in. Why?


How to find equation of motion for this trajectory? - object leaves curved ramp at a given velocity


If lead's electron configuration ends with 6p$^2$, shouldn't it be paramagnetic?


Does the order of variables matter for a quantum Lagrangian in the path integral formula for quantum mechanics?


Why is there a $\frac 1 2$ in $\frac 1 2 mv^2$?


Detection of the Electric Charge of a Black Hole


Isn't Dark Matter just an Indication that Relativity breaks down when describing large masses?


Beginner question: timelessness of massless particles


How does the Higgs mechanism work?


Help Me Gain an Intuitive Understanding of Lorentz Contraction


About the speed of light and gravity


Is acceleration relative?


Uncertainty and wave-trains


The paradoxical nature of Hawking radiation


Is the universe fundamentally deterministic?


Does juggling balls reduce the total weight of the juggler and balls?


Jump from a falling object


Online lecture videos on QCD?


What would happen to a person that was inside the Large Hadron Collider when it is turned on?


Are free electrons in a metal really free


Is electricity instantaneous?


interaction of mathematical structures (rephrased)


Video lectures on graduate level Classical Electrodynamics


Is there experimental evidence that massless particles such as photons attract massive objects?


Virtual photons, what makes them virtual?


Linearized equations


Why don't photons crash into each other occasionally? Or do they?


What's the shear rate in a turbulent flow?


Formulas for compressibility of solids (physics)


Is a hard drive heavier when it is full?


Does light accelerate or slow down during reflection?


Why are orbits elliptical?


What are the potential technological advances that the discovery of the Higgs boson may unlock?


Reference on Chern-Simons theory


Age of the Earth and the star that preceded the Sun


Time Dilation - How does it know which Frame of Reference to age slower?


Can solar furnace achieve higher temperature than sun surface?


Drag force at high speeds


Why do neutrinos propagate in a mass eigenstate?


Why are we not using thorium for energy?


What is the possibility of a railgun assisted orbital launch?


Can you split a photon?


How to correct flares and sharply focus on my telescope when viewing planets.


Why "Dark Energy" is called energy instead of force?


Why do we fall down when the bicycle slows down?


Change in momentum


Why electrons can't radiate in their atoms' orbits?


How much wind does it take to tip a sign over?


Leg Press & Actual Lifted Weight


Why do objects follow geodesics in spacetime?


Does more rain strike a vehicle while moving or while stopped (or neither)?


How are symmetries precisely defined?


How occurs the enantiomorph of the mirror?


conversion of information to energy


What happens to things when things get crushed in a blackhole


Is it possible to blur an image in such way that a person with sight problems could see it sharp?


Why would an electron in an orbit be accelerating continuously and would thus radiate away its energy and fall into the nucleus in a classical model?


Uniqueness of eigenvector representation in a complete set of compatible observables


Maximum helicopter height


Why work to change velocity from 0 to 20 km/h is less then from 20 to 40?


Dependence of Force as a function of Distance?


Expansion of a function


Is fire matter or energy?


Would atmosphere of Jupiter blow up if I launched a atomic bomb there?


Hubble time and its derivation?


Direction of friction when a car turns


Why does a cork float to the side of a glass?


how does the temperature of a gas increase when compressed by an external agent during sound production?


Why do Calabi-Yau manifolds crop up in string theory, and what their most useful and suggestive form?


Why did the Earth cool down?


The Equivalence Principle approaching the speed of light


Contracting Indices


Angular Momentum Conservation Definition


Freezing water in a closed container


How much oxygen would be consumed on a 1 cm squared surface which is on fire?


Why color of dress changes when water falls?


Sum of independent errors


Work done by magnetic field


A question on quantum computing?


Prerequisites for Griffiths electrodynamics


Flying a toy helicopter inside an accelerating train


Does magnetic propagation follow the speed of light?


Why earth looks always flat when it is round


Simulator for electrostatics


Why do people still talk about bohmian mechanics/hidden variables


Why do the planets' orbital distances fall on an exponential curve?


Is one way glass possible?


Two particles interacting by a inverse-square-law force, find their positions in function of time


Schrodinger's cat experiment


How does heat actually stay kept in the carbon molecules in the atmosphere?


Why are all force particles bosons?


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


Is it possible for a physical object to have a irrational length?


Pendulum with water dripping out


How to deduce the theorem of addition of velocities?


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


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?


Path integral formulation of quantum mechanics


Can someone be too late for being a great physicist?


Why current through all the resistors in series is considered to be same?


Rolling disk in inclined plane and flat plane?


What are the Time Operators in Quantum Mechanics?


How to get Planck length


Can inertial mass affect gravity of the object?


Measurement of Tangential Momentum Accomodation?


What happens to matter in a standard model with zero Higgs VEV?


How a fan moves air?


The definition of Lagrangian


How soon that a force affect another object?


How could vacuum energy cause the expansion of the universe?


The future of supersymmetry


In a neutron star - what force keeps the neutrons from getting closer and closer?


How are current and voltage out of phase in capacitive circuit?


At what speed will objects hit a singularity?


exponential potential $ \exp(|x|) $


Hydrostatic pressure at the center of a water planet


Strongest force in nature


Is it wasteful to use a heating element, instead of doing useful work?


Why can't some light ever reach earth?


The secret behind the spinning, asymmetrically weighted, 2D disk-shaped top?


Dark Energy saving the world


How do stars look like from space?


If the source of sound is vibration, why can't we "hear" a object whose molecules are vibrating?


Spinning of the Earth


Exchange particles-real or just mathetical constructs?


A Basic Question about Gravity, Inertia or Momentum or something along those lines


What does 1/k represent regarding Newtons Law of Cooling?


Flames with no gravity?


To which extent is general relativity a gauge theory?


Time taken for object in space to fall to earth


Time Slowing Down


What is the formula for determining time dilation (as the object in motion)?


How to find the potential energy?


Do cosmologically redshifted photons violate energy conservation?


How are the northern lights produced?


Quantum mechanic newbie: why complex amplitudes, why Hilbert space?


How to find the value of the parameter $a$ in this transfer function?


Relation between water flow and pressure


Thermo-Emf variation with temperature


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


How can a wooden spoon be used to prevent water from over boiling?


Massless charged particles


Linearizing Quantum Operators


What exactly is a kilogram-meter?


Will the hole on a metal disc expand or contract upon heating?


Quarks are now considered to be fundamentals, but so were atoms some time ago. So the way we see is only limited by our technological advances?


Does it exist a free good molecule / atom simulation software?


Current against the inverse of resistance graph, $I = V/R +c$


Good Magnetic Simulation Software?


Charging 12V 150Ah battery


Intuitive meaning of Dot Product


Does friction depend on the area between bodies thats in contact?


Can there be Electron and/or Proton Stars?


Magnet motor free energy generator


Is there any case in physics where the equations of motion depend on high time derivatives of the position?


Rutherfords alpha scattering conclutions?


Calculate the average temperature needed for hydrogen fusion reaction


Why does ice form on bridges even if the temperature is above freezing?


What is the difference between a white object and a mirror?


Halliday resnick physics book


Is a heavier skier faster?


Why aren't quarks free?


Superluminal expansion of the early universe how is this possible?


How does gamma ray emission make an atom more stable?


Gaussian Integral by Substitution


finding angular velocity and regular velocity when bouncing off a surface with friction


Why does Fukushima pressure rise?


How to make a monopole magnet?


What gives matter Gravitational Mass?


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


Brachistochrone Problem for Inhomogeneous Potential


Can expansion of space create energy?


Is there a Non-perturbative renormalization algorithm?


The relationship between the Hubble Constant and cosmological time


How were the crystal lattices of elements determined to perfection ? (Ex:- That of a copper is a cubic lattice )


Is Veneziano amplitude able to explain the physical properties of strongly interacting hadrons (such as proton and neutron)?


How to define angular momentum in other than three dimensions?


Origin of lepton/quark generations?


While Space-man lives for 1 day, then how long does Earth-man live ? 1000 years or 1 second?


Why do particular materials allow particular light waves to pass through them?


Can spacetime be non-orientable?


Nonzero ground state energy of the quantum harmonic oscillator


Dual nature of Matter at gross level


Why does coke fizz more when you add ice


What are the mechanics by which Time Dilation and Length Contraction occur?


Ultrasonic wave through air


How does dark matter halo outside a galaxy help to explain galaxy rotation curve?


Do COBE, WMAP, or Planck data show time-variance of the CMB's anisotropies?


Does the slinky base stay perfectly level during the initial free fall


Why doesn't a fly fall off the wall?


Any new texts directly on second law of thermodynamics?


Estimating the present state of stars


What happens if an atom absorbs a photon of energy higher than first excited state but lower than second excited state?


Why don't electric workers get electrocuted when only touching one wire?


What is the nature of energy?


Does kinetic friction increase as speed increases?


Special Relativity, 2nd Postulate -- Why?


Elastic potential energy of compressed spring?


What keeps objects made of gold apart?


Derivation of the Biot-Savart Law


Can a value of "length, in meters" be attributed to a pair of ends which are rigid (but not at rest) to each other?


How does the curiosity rover get it's power?


Why does the light bulb's brightness decrease?


Why do surfaces act like barriers for electrons?


Virtual particle production in space-time.


Kinematics question - Newton's Law of Motion


Capacitors discharging in series


What "time" is it for or on Voyager 1? If you could be "still" in the Universe who fast would time be?


Resistors in para and series circuit, finding volt


Attraction and repulsion of Magnetic materials


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


Would days be longer as the polar ice caps melt?


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


Why are higher order Lagrangians called 'non-local'?


Measurements and simultaneity


Could a super conductor actually be used to repel gravity?


Understanding weight on an inclined plane


Energy efficiency of antimatter producion


Do atmospheric physics prevent hot air balloons from ascending over 60,000ft?


Is Dark Energy Pushing Us Or Pulling Us?


The role of SO(3) and SU(2) in quantum mechanics


Gauge pressure vs. absolute pressure?


Matlab package: graphical calculus for quantum operations (esp. linear optics)


What is the present state of Mach's Principle amongst physicists?


If both radio waves and gamma rays can travel through walls


Algorithm of Lightning Strikes?


How do I find the frictional force using a free body diagram?