Einstein field equations
The equations of general relativity: not an unsolved problem, but highly nonlinear PDEs with famous exact solutions.
Exact statement
Ten coupled nonlinear partial differential equations for the space-time metric g, relating curvature (left side) to energy and momentum (right side).
Status
Not an open problem: established physics since 1915, with many exact solutions. Deep open questions remain about their general solutions (for example cosmic censorship).
Posed: 1915, Albert Einstein.
In plain words
The left side measures how space-time curves (Ricci tensor , scalar curvature , cosmological constant ); the right side is the stress–energy tensor of matter. 'Matter tells space-time how to curve; space-time tells matter how to move.'
There is no single 'answer'. You solve them for a given physical situation, usually with symmetry assumptions or on a computer (numerical relativity, used to predict the gravitational waves LIGO detected in 2015).
Key results so far
- 1952: Choquet-Bruhat proves the equations have a well-posed initial value problem (local existence).
- 1965–1970: Penrose and Hawking singularity theorems.
- 1993: Christodoulou and Klainerman prove the nonlinear stability of Minkowski space.
- open: Weak and strong cosmic censorship (Penrose, 1969) remain open in general.
Exact special solutions and solved cases
Schwarzschild (1916)
Outside a non-rotating, uncharged spherical mass; contains the simplest black hole.
FLRW cosmology (Friedmann 1922, Lemaître 1927, Robertson–Walker)
A homogeneous, isotropic expanding universe; the basis of Big Bang cosmology.
Kerr (1963)
Rotating black hole; Reissner–Nordström (1916–1918) adds electric charge; de Sitter (1917) is the vacuum with Λ > 0.
What our solver can and cannot do
The Einstein field equations are established physics, not an open problem. The solver shows the equations, famous exact solutions and their history; solving them for a new physical situation needs specialised numerical methods. Open the solver.
Frequently asked questions
- What do the Einstein field equations say?
- Ten coupled nonlinear partial differential equations for the space-time metric g, relating curvature (left side) to energy and momentum (right side).
- Are the Einstein field equations an unsolved problem?
- Not an open problem: established physics since 1915, with many exact solutions. Deep open questions remain about their general solutions (for example cosmic censorship).
- Can MathGPT solve the Einstein field equations?
- MathGPT shows the statement, who settled it and how, with references; the proof itself is in the cited papers.
References
- A. Einstein, 'Die Feldgleichungen der Gravitation', Sitzungsberichte Preuss. Akad. Wiss. (1915).
- C. Misner, K. Thorne, J. Wheeler, Gravitation (1973).
- R. Wald, General Relativity, Chicago (1984).