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.”
Nihilism
Holds that life has no inherent meaning, purpose, or intrinsic value — any meaning people find is a human invention rather than a discovery about the world.
String Theory Landscape / Multiverse
String theory permits an enormous number of possible vacuum states, each potentially describing a different universe with different physical constants.
Utilitarianism
Holds that the right action — and, by extension, a meaningful life — is one that maximizes overall well-being or happiness and minimizes suffering for all affected.
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.
Moral Realism vs. Anti-Realism
A framing problem rather than a single theory: whether moral facts and values exist objectively, independent of what any person or culture believes (realism), or are constructed, relative, or expressions of attitude (anti-realism) — a fault line underlying every other ethics-of-meaning theory.
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 lower-dimensional surface.
The Fermi Paradox
The framing problem for this whole domain: the apparent contradiction between plausible estimates that the galaxy should host many communicating civilizations, and the total absence of confirmed contact or evidence for any of them.
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 — used as a stress-test against theories.