Physics Formulae/Special Relativity Formulae
Lead Article: Tables of Physics Formulae
This article is a summary of the laws, principles, defining quantities, and useful formulae in the analysis of Special Relativity. There are essentially two formulations in relativity, using conventional 3-vectors with addtional time components, or the more unified formalism of four-vectors.
3-Vector Formulation
[edit | edit source]3-Vectors are conventional vectors, of dimension 3. The components are spatial corresponding to the coordinate system used. It matters not which coordinate system is used, events in space-time can only be independant of coordinates, since coordinates are simply labels to locate a point.
Einstien's Assumptions of Special Relativity
[edit | edit source]For all inertial frames of referance the following are invariant:
- Physical Laws
- Luminal Speed
Note that the second two are corolaries of the first. Since some physical laws include properties of light, often relating to the vacuum luminal speed, if the laws are to be the same for all observers in inertial referance frames, the speed of light in a vacuum must be constant.
Inertial Frames and Lorentz Transforms
[edit | edit source]Two important and very useful simplifying parameters are the lorentz factor and rapidity.
Lorentz Factor | |
Rapidity |
Lorentz transforms are linear transformations, relating the coordinates of an event in one frame F to another F' , where
F' moves at constant velocity v relative to F, equivalant to
F moving at constant velocity (-v) relative to F' .
The observers in each frame measure different coordinates for the same event. By this argument the inverse transforms can be deduced simply by:
- interchanging the frame coordinates
- changing the sign
Lorentz Transformation
for Space-Time |
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Lorentz Transformation
for Momentum-Energy |
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Relativistic Doppler Effect | |
Doppler Shift |
Often a common misonception is to obtain the incorrect sign for the relative velocity v.
Reformulation of Quantities
[edit | edit source]Space-Time
[edit | edit source]Proper Time | |
Proper Length | |
Space-Time Invariant |
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Time Dilation | |
Length Contraction |
Energy-Momentum
[edit | edit source]Rest Mass-Energy | |
Momentum-Energy Invariant |
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Relativitic Mass | |
Momentum | |
Kinetic Energy | |
Total Energy |
4-Vector Formulation
[edit | edit source]4-Vector Nomenclature Summary
[edit | edit source]General 4-Vectors | |
General 4-Vector Lorentz Transform
Transition matrix of coordinates between a frame F and another frame F' moving at velocity v in common x-x' direction relative to F. The inverse matrix is the inverse transform, from F' to F, F moving in common (-x)(-x') direction relative to F'. |
Note that (symmetric matrix) (non-singular/invertible) as should be for Lorentz Invariance. |
Space-Time 4-Vector | |
Momentum-Energy 4-Vector |
Lorentz Transform
[edit | edit source]Space-Time |
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Energy-Momentum |
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External Links
[edit | edit source]4-Vectors
Lorentz Transforms
Space-Time
Mass-Energy Equivalance