Special and General Relativity Forum

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Join in expert discussion on special and general relativity discussion. Relativity is the dependence of various physical phenomena on relative motion of the observer and the observed objects.
Undergrad Newton's Gravity & Lorentz Contraction: Is Modification Needed?
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Undergrad An issue with length contraction
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Undergrad Solving for Extrema of Proper Time Integral
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Undergrad Black hole horizon for different observers
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Undergrad Can Curves Live Out of Embedding Diagrams?
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High School Grandfather Paradox & Self Consistency Principle: Are They Different?
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Undergrad Coordinate and time transformations
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Undergrad Theory Without Spacelike Separations: Can It Exist?
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High School Time Dilation & Bosons: Decay Rate Changes?
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Undergrad Does light take longer to go a set distance on a train?
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Undergrad Force due to acceleration and time flowing differently
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Graduate Is it possible for variable speed of light in a vacuum?
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Undergrad Some thoughts about Bell's string paradox alternatives
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Undergrad Understand 4-Vectors & Spacetime: Hartle Gravity Chapter 5
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Undergrad Beginner's Guide to GR: Questions & Answers
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Undergrad Connection & Affine Geodesics: Q&A
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Undergrad Time difference caused by length contraction
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Undergrad Geometries from Line Element $$dl^2=d\theta^2 + \sin^2\theta\, d\varphi^2$$
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Undergrad Calculation of gravitational redshift in an accelerating elevator
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Undergrad Tipler 1976: Clarifying Symbol Meaning
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Undergrad Can we determine the one way speed of light by combined measurements?
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Undergrad Measuring Time & Spatial Distances: Timelike vs Spacelike
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High School Problem about postulate of the invariance of the speed of light
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Undergrad What Would it Look Like to Fall into a Black Hole?
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Graduate Potential Energy of Relativistic Particles in Coulomb Field
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Undergrad Coordinate System Transformation: Lowering/Raising Indices Explained
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Undergrad When and how can I apply Born rigidity condition?
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Undergrad What is the definition of proper time interval according to Wikipedia?
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Undergrad Trying to understand space-time diagrams
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Undergrad Energy of Light in Accelerating Universe: Comparing Cases
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Undergrad Reconciling Lorentz Four-Force Density w/ Spacelike Four-Current (##c = 1##)
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High School Historic question regarding SR and c*t
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High School Experimental evidence for effective mass increasing with speed
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Undergrad What, exactly, are invariants?
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High School Light Taking U-Turn: Transformation of Star to Black Hole
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Undergrad Difference Between Lorentz Transformation & Special Relativity
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Undergrad Hartle, Gravity pg 34: Question about Time in Non-Inertial Frames
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High School Sign of Expansion Scalar in Expanding FLRW Universe
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High School Gravitational acceleration and sub-atomic electric charge
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Undergrad Why are acceleration, jerk, etc not relative, just like velocity?
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High School Einstein's Twin Paradox: Confusing Solution?
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Undergrad Carroll GR: Geodesic Eq from Var Principles
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Undergrad Using position of free particle to measure time
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Undergrad Equations of Motion for Massless Particle in Potential
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Undergrad Def Proper Time GR: Half or Integral Along Path?
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Graduate Can a Null Surface Satisfy the Requirements for a Cauchy Surface?
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Graduate What is the formal definition of spacetime in physics?
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Undergrad Coord Transform in de Sitter Space: Phys Significance &Linearity?
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Undergrad Richard Feynman: Deriving Lorentz Mass Transformation
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Undergrad Appearance of Warp Bubble Internal Volume to Distant Observer
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Undergrad Carroll GR: Tangent Space & Partial Derivatives
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Graduate What does G mean in general relativity?
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Graduate Computing Thomas Precession: Part 2 | Francesco
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Graduate Computing the Thomas Precession: Help from PFers Needed!
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High School Does the CMB give us absolute space and time in practice?
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High School (ELI5) why can’t massless particles travel infinitely fast?
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Undergrad Michelson-Morley: Errors in Calculations?
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Undergrad Wormholes & Warp Drives: Can Circular Polarizers Create Them?
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Undergrad Calculate Contraction 2nd & 4th Indices Riemann Tensor
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High School Does Force Travel Faster Than Light?
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High School General Relativity & Grav. Time Dilation Qn
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Undergrad Matter Gaining Energy from Expanding Spacetime?
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Undergrad Difference Between Locally Flat & Locally Inertial?
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Undergrad Does Special and General Relativity Affect Aging of Apollo Astronauts?
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High School Gravitational Potential Energy & Mass Change: Andrew's Question
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Undergrad Calculate Gaussian Curvature from 4D Metric Tensor
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High School High Frequency Photons: More Mass, More Bend?
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Undergrad Cosmic Inflation Explained: Constant Velocity of Electromagnetic Radiation
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Graduate Relativistic Relative Velocity Comp.: Bini, D. et al. (1995)
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High School Differences in Predictions between SR and LR?
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Undergrad Spacetime interval and basic properties of light
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Graduate Can discrete temporal symmetries exist in general relativity?
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Undergrad Understanding Simultaneity Through Male & Female Clocks Meeting
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Undergrad Karl Schwarzschild: Solving GR on the Eastern Front
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Undergrad Effect of Black Hole Spin on Gravity
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High School What Causes Mass to Exert Gravitational Pull?
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Graduate Solving Equation 15.43 Line 2 to 3 in Tevian Dray's Differential Forms
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Undergrad Spatially Homogeneous Scalar Field on Spacetime: Showing $\nabla^2 f$
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Graduate (paper) Stability properties of Kerr BH's
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Undergrad Being at the position of a singularity before it is formed
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High School Can gravitational time dilation explain the galaxy rotation curve?
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Undergrad 4D d'Alembert Green's function for linearised metric
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High School Andy Weir's "Hail Mary": Question About Relativistic Rocket
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High School Twin Paradox (3 objects version)
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Undergrad Calculating Particle Redshift at Time t_0 & t_1
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Undergrad The Derivative Nature of Time and Its Relation to Earth's Rotation and Speed
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Undergrad Follow Up on M. LeBellac & J.M. Levy-Leblond's "Galilean Electromagnetism
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Graduate What assumptions underly the Lorentz transformation?
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Undergrad How is proper time visualized in the FLRW metric's 4D spacetime geometry?
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Undergrad Only Minkowski or Galilei from Commutative Velocity Composition
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Undergrad Gravity Wave Speed: Deriving Constancy from Maxwell Eqs.
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Undergrad Understanding Covariant and Partial Derivatives in General Relativity
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Undergrad Lorentz Transformation Derivation: Assumptions Req'd?
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High School Calculating Time Dilation w/ Light Clock - Implications & Mistakes?
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High School Cosmic Inflation & Censorship: Validation or Corrections?
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Undergrad What Happens Inside BH Event Horizon?
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Undergrad Calculating Relative Change in Travel Time Due to Spacetime Perturbation
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Undergrad Please help with my spacetime diagrams (relativity problem)
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High School Time: What We Read On The Clock?
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Undergrad Diagonal Matrix of Stress-Energy Tensor: Why?
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