Beyond Physics
Theories of What Might Lie Beyond Our Universe
The Multiverse - Level I
If space is infinite and uniformly filled with matter, then everything that can happen will happen—infinitely many times. Beyond our cosmic horizon exist countless other observable universes, exact copies of ours along with every possible variation. Somewhere, another you is reading this exact text.
Many-Worlds Interpretation
Every quantum measurement causes the universe to split into parallel branches, one for each possible outcome. There's no wave function collapse—all possibilities are realized in an ever-branching tree of parallel realities. Schrödinger's cat is both alive and dead, just in different worlds.
Eternal Inflation
Inflation never fully stops—while it ends in some regions (creating "bubble universes" like ours), it continues eternally in others, spawning infinite new universes. Each bubble can have different physical constants and laws. Our Big Bang was just one bubble nucleating in an eternally inflating multiverse.
The String Theory Landscape
String theory permits approximately 10^500 different vacuum states, each corresponding to a possible universe with unique physical laws and constants. This "landscape" of possibilities may be realized through eternal inflation—each bubble universe randomly selects one configuration. Our universe's laws are just one point in this vast landscape.
Brane Cosmology
Our universe is a 3-dimensional "brane" (membrane) floating in a higher-dimensional "bulk" space. Multiple branes could coexist mere millimeters away in extra dimensions, yet remain invisible to us. Gravity might "leak" between branes, explaining its weakness. Colliding branes may even trigger Big Bangs.
The Holographic Universe
All the information in our 3D universe can be encoded on a 2D surface at its boundary—like a hologram. The holographic principle suggests that reality as we experience it is a projection from information stored on a distant 2D surface. This resolves black hole information paradoxes and hints at the nature of quantum gravity.
The Mathematical Universe
Physical reality IS a mathematical structure. Every mathematically consistent structure exists physically as a universe. Our universe is one specific mathematical object, while other mathematical structures exist as parallel universes with entirely different mathematical laws—not just different constants, but different fundamental mathematics.
Quantum Foam
At the Planck scale (10^-35 meters), spacetime itself becomes a seething foam of quantum fluctuations. Virtual black holes and wormholes constantly form and dissolve. The smooth fabric of spacetime we experience is merely an averaged-out view—zoom in far enough and reality becomes a chaotic quantum soup where space and time lose meaning.
Conformal Cyclic Cosmology
The universe undergoes infinite cycles of Big Bangs. When our universe reaches its far future heat death (infinite expansion, maximum entropy), the loss of all mass-bearing particles makes it geometrically identical to a new Big Bang. The end of one aeon becomes the beginning of the next, eternally. We may find "Hawking points" in the CMB as echoes from previous aeons.