# Relativity

> Special and general relativity theory

- Skill: `ffsshhttiikk/relativity` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ffsshhttiikk/relativity`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ffsshhttiikk/relativity/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MIT
- Author: ffsshhttiikk (https://skillmd.com/u/ffsshhttiikk)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ffsshhttiikk/relativity

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## What I do
- Analyze time dilation and length contraction
- Calculate relativistic momentum and energy
- Model spacetime diagrams and worldlines
- Study gravitational lensing and black holes
- Apply equivalence principle concepts
- Analyze cosmological metrics

## When to use me
When studying high-speed phenomena, gravitational physics, or cosmology.

## Key Concepts
- **Lorentz Factor**: γ = 1/√(1 - v²/c²) for time dilation and length contraction
- **Mass-Energy Equivalence**: E = mc², relativistic momentum p = γmv
- **Spacetime Interval**: ds² = -c²dt² + dx² + dy² + dz² (invariant)
- **Einstein Field Equations**: G_{μν} = (8πG/c⁴) T_{μν} relates geometry to matter
- **Schwarzschild Metric**: Describes spacetime outside spherical mass
- **Gravitational Redshift**: z = √((1-r_s/R)/(1-r_s/r)) - 1