Multiverse

Scientists speculate that ours might not be the only universe out there — we might instead live in a set of infinite or parallel universes called a "multiverse". Infinite universes are a consequence of several scientific theories; for instance, if spacetime truly goes on forever it might start repeating eventually, since particles can only be arranged a finite number of ways. A multiverse could also arise from "bubble universes," pockets of space in an inflating universe that are never able to meet; or parallel universes, where multiple 3D universes are held in higher-dimensional space, unable to interact. While some universes in a multiverse might be like our own, others could have wildly different laws of physics and fundamental constants.

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Parallel universe: Artist's depiction of quantum bubbles and multiverses.

Do parallel universes exist? We might live in a multiverse.

By Vicky Stein

There are a few good theories for a multiverse — an infinite number of parallel universes besides our own.

Different observations of the same reality (in photons) may both be correct, according quantum mechanics.

More Than One Reality Exists (in Quantum Physics)

By Mindy Weisberger

Can two versions of reality exist at the same time? Physicists say they can — at the quantum level, that is.

High mountain peaks glowing in the moonlight.

A Mirror Image of Our Universe May Have Existed Before the Big Bang

By Erik Vance

Before the Big Bang, time may have run in reverse.

Our Universe Could Be An Expanding Bubble in an Extra Dimension

By Adam Mann

Is our universe sitting on the edge of an expanding bubble?

Why Alternate Universes Might Also Host Life Around their Stars

By Charles Q. Choi

What might stars be like in other universes?

String Theory May Create Far Fewer Universes Than Thought

By Clara Moskowitz

Some physicists claim the popular landscape of universes in string theory may not exist.

Alien Thinking: The Conceptual Space Art of Jonathon Keats

By Mike Wall

A look at the space-themed works of experimental philosopher Jonathon Keats.

Aliens May Well Exist in a Parallel Universe, New Studies Find

By Brandon Specktor

Could alien life be hiding in the multiverse? New studies say, "sure!"

Stephen Hawking's Final Paper Cuts the Multiverse Down to Size

By Rafi Letzter

The great physicist's library of work is now complete.

Stephen Hawking's Last Paper (Probably) Doesn't Prove We Live in a Multiverse

By Tia Ghose

Stephen Hawking's last paper has been touted to provide a way to finally test for the existence of a multiverse, but it's unlikely to do that, several experts said.

Stephen Hawking's Final Paper Proposes Way to Detect the 'Multiverse'

By Mike Wall

Stephen Hawking's final research paper could help astronomers find evidence that our universe is just one among many in a larger "multiverse," according to media reports.

Stephen Hawking's Best Books: Black Holes, Multiverses and Singularities

By Sarah Lewin

Physicist Stephen Hawking, whose death was announced March 14, wrote prodigiously for both a popular audience and the scientific community over the course of his career. Here are the highlights.