Domain
Physics & Cosmology
Lambda-CDM Model (Big Bang)
The standard model of cosmology: the universe began ~13.8 billion years ago from an extremely hot, dense state and has been expanding and cooling ever since.
Cosmic Inflation
A brief period of exponential expansion in the first fraction of a second after the Big Bang, proposed to solve the horizon and flatness problems.
Eternal Inflation
A extension of inflation theory suggesting that inflation never fully stops, endlessly spawning new "bubble universes" — the mechanism behind many multiverse proposals.
Steady-State Theory
A historical rival to the Big Bang proposing the universe has no beginning or end, with matter continuously created as it expands to keep density constant.
Ekpyrotic / Cyclic Universe
Proposes the universe undergoes endless cycles of expansion and contraction, with each Big Bang triggered by the collision of higher-dimensional "branes."
String Theory Landscape / Multiverse
String theory permits an enormous number of possible vacuum states, each potentially describing a different universe with different physical constants.
Loop Quantum Cosmology
Applies loop quantum gravity to cosmology, suggesting the Big Bang was actually a "Big Bounce" from a prior contracting universe rather than a true beginning.
Holographic Principle
Suggests all information in a volume of space can be described by information on its boundary — implying our 3D universe may be encoded on a…
Simulation Hypothesis
Proposes that what we perceive as reality could be an artificial simulation, most famously formalized as a probabilistic trilemma about advanced civilizations.
Boltzmann Brain Problem
A thought experiment/paradox arising from certain cosmological models, in which random thermodynamic fluctuations should statistically produce far more isolated self-aware "brains" than entire ordered universes —…