---
id:"kb-2026-00333"
title:"Theory of Relativity"
schema_type:"TechArticle"
category:"science"
language:"en"
confidence:"high"
last_verified:"2026-05-22"
generation_method:"ai_assisted"
ai_models:["claude-opus"]
derived_from_human_seed:true
primary_sources:
  - title:"Relativity: The Special and General Theory (Einstein, 1916)"
    type:"book"
    year:1916
    url:"https://www.gutenberg.org/ebooks/5001"
    institution:"Project Gutenberg"
secondary_sources:
  - title: "MDN Web Docs — HTTP"
    type: "documentation"
    year: 2026
    url: "https://developer.mozilla.org/en-US/docs/Web/HTTP"
    institution: "Mozilla"
completeness: 0.88
ai_citations:
  last_citation_check:"2026-05-22"
---

## TL;DR

Einstein's relativity (1905 Special, 1915 General) redefined space, time, and gravity. Special relativity: laws of physics same for all non-accelerating observers; speed of light is constant → time dilation, length contraction, E=mc². General relativity: gravity is curvature of spacetime by mass/energy.

## Core Explanation

Special relativity: time slows for moving objects (experimentally confirmed — GPS satellites must correct for relativistic effects). E=mc²: mass can convert to energy. General relativity: predicted black holes, gravitational waves (detected 2015 by LIGO), expansion of universe. Einstein's happiest thought (1907): free-falling person doesn't feel own weight — equivalence principle.

## Further Reading

- [Relativity: The Special and General Theory (Einstein, 1916)](https://www.gutenberg.org/ebooks/5001)