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Special and General Relativity Forum

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.

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I Question about an entanglement paper

Feb 18, 2019 · Replies 52 · Jun 13, 2019

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Replies: 52

Views: 6K

I How Do Rockets Traveling at High Speeds Observe Each Other's Velocity?

Jun 13, 2019 · Replies 6 · Jun 13, 2019

Replies: 6

Views: 2K

I The velocity of a moving frame of reference

Jun 1, 2019 · Replies 111 · Jun 11, 2019

4

Replies: 111

Views: 9K

I Alternative form of geodesic equation for calculating Christoffels

Jun 11, 2019 · Replies 1 · Jun 11, 2019

Replies: 1

Views: 1K

I Is it possible to have synchronized clocks in a rotating system?

Jun 9, 2019 · Replies 55 · Jun 11, 2019

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Replies: 55

Views: 4K

B Can I keep multiple clocks in sync after a ride on a roller coaster?

Jun 11, 2019 · Replies 17 · Jun 11, 2019

Replies: 17

Views: 2K

I Question regarding the nature of mass inside a black hole

May 21, 2019 · Replies 39 · Jun 11, 2019

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Replies: 39

Views: 4K

B Rest Energy and a 1 million solar mass black hole

Jun 8, 2019 · Replies 48 · Jun 11, 2019

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Replies: 48

Views: 4K

I Can an object fall into a black hole at faster that the speed of light?

May 14, 2019 · Replies 7 · Jun 10, 2019

Replies: 7

Views: 2K

I Radius in Schwarzschild Metric: Definition Explained

Jun 8, 2019 · Replies 7 · Jun 9, 2019

Replies: 7

Views: 3K

I Do clocks on Bell’s spaceships stay synchronized?

Jun 6, 2019 · Replies 27 · Jun 9, 2019

Replies: 27

Views: 3K

I Tensor Field Notation: Einstein Gravity Explained

Jun 6, 2019 · Replies 14 · Jun 8, 2019

Replies: 14

Views: 2K

I Space-Like Hypersurface: Simultaneous Events?

Jun 8, 2019 · Replies 2 · Jun 8, 2019

Replies: 2

Views: 2K

B Does my speedy spaceship (.999+C) have a temperature?

Jun 5, 2019 · Replies 31 · Jun 6, 2019

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Replies: 31

Views: 2K

I Special Relativity: Train in Tunnel Paradox Solved

Jun 6, 2019 · Replies 6 · Jun 6, 2019

Replies: 6

Views: 2K

B Can Canceling Orbital Motion Improve Rocket Efficiency?

Jun 3, 2019 · Replies 90 · Jun 6, 2019

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Replies: 90

Views: 8K

I Covariant derivative of the contracted energy-momentum tensor of a particle

Jun 3, 2019 · Replies 22 · Jun 6, 2019

Replies: 22

Views: 4K

A Do Moving Masses Slow Down Due to Gravitational Waves?

Jun 4, 2019 · Replies 5 · Jun 5, 2019

Replies: 5

Views: 1K

B Train platform -- light speed and time quandry

Jun 4, 2019 · Replies 14 · Jun 5, 2019

Replies: 14

Views: 2K

I Is there a solution for the behavioural contradiction in RT?

Jun 3, 2019 · Replies 35 · Jun 4, 2019

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Replies: 35

Views: 3K

I Measuring Mass of a Bowling Ball Dropped into a Black Hole

May 31, 2019 · Replies 31 · Jun 4, 2019

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Replies: 31

Views: 3K

B Planck Length: Upper Limit on Photon Frequency & Momentum

May 22, 2019 · Replies 7 · Jun 4, 2019

Replies: 7

Views: 2K

Insights Can I Send a Signal Faster than Light by Pushing a Rigid Rod? - Comments

Sep 25, 2015 · Replies 21 · Jun 3, 2019

Replies: 21

Views: 6K

I Derivation of Geodesics Eq from EM Tensor of Point Particle

Jun 2, 2019 · Replies 7 · Jun 2, 2019

Replies: 7

Views: 2K

I Issue With Derivation of Gravitational Time Dilation

Apr 19, 2019 · Replies 16 · Jun 2, 2019

Replies: 16

Views: 3K

I Gravitational Potential Energy in GR

May 17, 2019 · Replies 13 · Jun 1, 2019

Replies: 13

Views: 2K

B Prereqs for Posting in Special & General Relativity

Jun 1, 2019 · Replies 1 · Jun 1, 2019

Replies: 1

Views: 1K

Insights Understanding Precession in Special and General Relativity

May 26, 2019 · Replies 16 · Jun 1, 2019

Replies: 16

Views: 2K

B Why is time orthogonal to space?

Apr 7, 2019 · Replies 39 · May 31, 2019

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Replies: 39

Views: 6K

A Thermal State in Relativity Theory: Can It Happen?

May 23, 2019 · Replies 7 · May 30, 2019

Replies: 7

Views: 2K

I Accelerated Triangle and Length Contraction

May 26, 2019 · Replies 40 · May 30, 2019

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Replies: 40

Views: 4K

B Effects on time by gravity or motion

May 27, 2019 · Replies 31 · May 29, 2019

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Replies: 31

Views: 2K

A Forgetting Non-GR Physics: How Specialists Can Stay Sharp

May 27, 2019 · Replies 5 · May 29, 2019

Replies: 5

Views: 2K

I Stress-Energy Tensor: Specified or Calculated?

May 26, 2019 · Replies 3 · May 27, 2019

Replies: 3

Views: 2K

B Is this an adequate thought experiment?

May 23, 2019 · Replies 6 · May 26, 2019

Replies: 6

Views: 2K

I Modifying EFE to Match Newton's Gravity Predictions

May 21, 2019 · Replies 32 · May 26, 2019

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Replies: 32

Views: 3K

I Measuring Gravity Wave Time Distortion Accuracy

May 24, 2019 · Replies 5 · May 24, 2019

Replies: 5

Views: 2K

I What is the Strange Solution to the EFE with a Born Frame and Rotating System?

May 9, 2019 · Replies 49 · May 24, 2019

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Replies: 49

Views: 6K

I Simultaneity of two light rays in different reference frames

May 21, 2019 · Replies 16 · May 24, 2019

Replies: 16

Views: 3K

B Can we produce black holes by particle accelerators?

May 12, 2019 · Replies 4 · May 23, 2019

Replies: 4

Views: 2K

B Twins Paradox: Dropping a Ball from a Moving Train

Apr 3, 2019 · Replies 87 · May 23, 2019

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Replies: 87

Views: 11K

B Einstein's train and simultaneity

Nov 26, 2018 · Replies 22 · May 22, 2019

Replies: 22

Views: 5K

I How Do Physical Quantities Relate to Spacetime in Einstein's Field Equations?

May 20, 2019 · Replies 8 · May 21, 2019

Replies: 8

Views: 2K

B Why do things in free fall accelerate?

Apr 16, 2019 · Replies 47 · May 20, 2019

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Replies: 47

Views: 6K

I Boosting to an instantaneous rest frame

May 14, 2019 · Replies 16 · May 19, 2019

Replies: 16

Views: 5K

I Newton vs Einstein: Explaining Other Forces

May 19, 2019 · Replies 2 · May 19, 2019

Replies: 2

Views: 1K

A Index Juggling: Angular Momentum Tensor & Inertia Tensor in 3D-Space

May 16, 2019 · Replies 3 · May 18, 2019

Replies: 3

Views: 2K

I Can empty space be considered ‘elastic’ and expandable?

May 15, 2019 · Replies 28 · May 18, 2019

Replies: 28

Views: 3K

B Bell's Spaceship Paradox & Length Contraction

Jul 18, 2018 · Replies 76 · May 18, 2019

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Replies: 76

Views: 10K

A Significance of "Change of Signature" in Classical Relativity

May 14, 2019 · Replies 14 · May 16, 2019

Replies: 14

Views: 2K

B Gravitational Effect from Relativistic Mass: Answers & Questions

May 13, 2019 · Replies 6 · May 14, 2019

Replies: 6

Views: 2K

Model Near-Colliding Ultra-Relativistic BHs w/ Colliding PP Waves

Feb 22, 2019 · Replies 5 · May 14, 2019

Replies: 5

Views: 2K

A Solving Møller Energy Distribution Problem in Paper

May 12, 2019 · Replies 7 · May 14, 2019

Replies: 7

Views: 2K

I Gravitational potential gradient in accelerated reference frames?

May 13, 2019 · Replies 1 · May 13, 2019

Replies: 1

Views: 1K

B Bohr's Views on Relativity: What Did He Think?

May 13, 2019 · Replies 5 · May 13, 2019

Replies: 5

Views: 1K

I Is there such a phenomenon as "micro-frame drag"

May 8, 2019 · Replies 8 · May 13, 2019

Replies: 8

Views: 2K

A Electromagnetic Stress Energy Tensor Formula (-,+,+,+)

May 12, 2019 · Replies 3 · May 13, 2019

Replies: 3

Views: 2K

B Event Horizon: Understanding the Singularity of a Black Hole

May 11, 2019 · Replies 5 · May 12, 2019

Replies: 5

Views: 2K

I Orthonormal Basis - Definition & Examples

May 11, 2019 · Replies 2 · May 11, 2019

Replies: 2

Views: 1K

B Polarized Electron in a Rotating Reference Frame

May 7, 2019 · Replies 37 · May 11, 2019

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Replies: 37

Views: 4K

B Spacetime interval - alternative view - maybe?

May 10, 2019 · Replies 14 · May 10, 2019

Replies: 14

Views: 2K

B Deriving the Lorentz transformations

May 10, 2019 · Replies 4 · May 10, 2019

Replies: 4

Views: 1K

I Invariant Mass in Gravitational Fields: Special Relativity

May 9, 2019 · Replies 17 · May 10, 2019

Replies: 17

Views: 2K

I Length Contraction: Measuring a Difference of 55 Nanometers

May 8, 2019 · Replies 3 · May 9, 2019

Replies: 3

Views: 1K

A couple of interesting black hole papers

Nov 16, 2012 · Replies 2 · May 8, 2019

Replies: 2

Views: 2K

I Does Curving Space by an Approaching Mass Do Work?

May 7, 2019 · Replies 4 · May 8, 2019

Replies: 4

Views: 2K

Understanding Stokes Theorem and is the variation of the metric a tensor?

May 2, 2007 · Replies 3 · May 8, 2019

Replies: 3

Views: 5K

I Can all fundamental constants be set to 1 in natural unit systems?

May 7, 2019 · Replies 3 · May 7, 2019

Replies: 3

Views: 2K

SR Foundations: Parallax Methods? - Reference Request

Feb 13, 2012 · Replies 2 · May 7, 2019

Replies: 2

Views: 2K

Insights Defining Large-Scale Isotropy: A Formal Definition

May 7, 2019 · Replies 0 · May 7, 2019

Replies: 0

Views: 1K

B Relativator: The circular slide-rule for physicists

Aug 28, 2014 · Replies 2 · May 7, 2019

Replies: 2

Views: 3K

Relativity Visualization: Aging Twin Paradox - Adam Toons

Apr 20, 2008 · Replies 1 · May 7, 2019

Replies: 1

Views: 2K

Correcting a Typo in d'Inverno's Lagrangian on Page 172 | Section 11.3 Results

Aug 7, 2008 · Replies 1 · May 7, 2019

Replies: 1

Views: 2K

Rotating black hole interiors take 2

Nov 19, 2006 · Replies 1 · May 7, 2019

Replies: 1

Views: 2K

Price's Power Law: Mass-Energy Dampening & h Constant

Feb 28, 2009 · Replies 1 · May 7, 2019

Replies: 1

Views: 2K

Vanishing twist of time - like killing field

Mar 11, 2013 · Replies 1 · May 7, 2019

Replies: 1

Views: 3K

EP and active/passive mass

Nov 20, 2011 · Replies 1 · May 7, 2019

Replies: 1

Views: 2K

B Should the 'time' axis of a Minkowski diagram be time's imaginary unit?

May 4, 2019 · Replies 11 · May 7, 2019

Replies: 11

Views: 2K

I What is ds in ds2 = dx2 - cdt2

May 5, 2019 · Replies 9 · May 5, 2019

Replies: 9

Views: 5K

B Trying to understand Lorentz Transformations

Mar 19, 2019 · Replies 69 · May 5, 2019

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Replies: 69

Views: 8K

Light interferometry as described in Thorne's black holes and time warps ?

May 25, 2010 · Replies 3 · May 5, 2019

Replies: 3

Views: 2K

I Black Holes: Time Bidirectional?

May 4, 2019 · Replies 3 · May 5, 2019

Replies: 3

Views: 1K

B Implications of FTL signals in SR

Aug 23, 2018 · Replies 16 · May 4, 2019

Replies: 16

Views: 2K

I Fixing Rindler Coordinates when a=0

May 2, 2019 · Replies 7 · May 2, 2019

Replies: 7

Views: 1K

I Is a photon simply a vibration of the spacetime lattice?

May 1, 2019 · Replies 33 · May 2, 2019

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Replies: 33

Views: 3K

B Does Time Exist Without Motion?

Apr 20, 2019 · Replies 4 · Apr 29, 2019

Replies: 4

Views: 2K

A Coord Transf. in Linearized GR: Understanding Metric Transformation

Apr 25, 2019 · Replies 5 · Apr 29, 2019

Replies: 5

Views: 2K

Einstein-Hilbert Action -> GR is a saddle point?

Sep 26, 2010 · Replies 4 · Apr 28, 2019

Replies: 4

Views: 3K

B Understanding Final Form of Lorentz Transformations

Apr 23, 2019 · Replies 12 · Apr 28, 2019

Replies: 12

Views: 2K

Restframe of Photon: Explained

Apr 26, 2019 · Replies 5 · Apr 27, 2019

Replies: 5

Views: 2K

Question about "Rest frame of a photon" FAQ

Apr 26, 2019 · Replies 19 · Apr 27, 2019

Replies: 19

Views: 3K

Curved-spacetime, but why curved coordinates?

Nov 7, 2011 · Replies 4 · Apr 26, 2019

Replies: 4

Views: 3K

Gaussian to MKS Four-vector Conversion

Oct 21, 2009 · Replies 1 · Apr 26, 2019

Replies: 1

Views: 2K

Is the Schwarzschild spacetime with negative mass geodesically complete?

Mar 8, 2011 · Replies 1 · Apr 26, 2019

Replies: 1

Views: 3K

B Is Time Relative? Understanding Special Relativity

Apr 25, 2019 · Replies 45 · Apr 26, 2019

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Replies: 45

Views: 10K

I CMB Photons: 3000˚ K to 2.7˚ K in an Expanding Universe

Apr 25, 2019 · Replies 12 · Apr 26, 2019

Replies: 12

Views: 2K

Hawking singularity theorem - what if not all geodesics incomplete?

Sep 8, 2010 · Replies 1 · Apr 25, 2019

Replies: 1

Views: 3K

Experimental tests of zero divergence for stress-energy?

Sep 15, 2012 · Replies 1 · Apr 25, 2019

Replies: 1

Views: 3K

Wiki article on Unruh radiation

Nov 11, 2013 · Replies 1 · Apr 25, 2019

Replies: 1

Views: 2K

Gullstrand-Painlevé coordinates

Dec 19, 2008 · Replies 1 · Apr 25, 2019

Replies: 1

Views: 3K

Relativity

The theory of relativity, formulated by Albert Einstein, comprises two fundamental theories—special and general relativity. Special relativity, proposed in 1905, redefines our understanding of space and time by asserting the constancy of the speed of light for all observers and introducing concepts like time dilation and length contraction.

General relativity, presented in 1915, extends these principles to incorporate gravity. It describes gravity as the curvature of spacetime caused by massive objects, leading to phenomena like gravitational time dilation and the prediction of black holes. Einstein's equations have been consistently validated through experiments and observations, profoundly influencing our comprehension of the universe's fabric and dynamics.

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