The universe is big, but it’s peanuts compared to the eternally inflating multiverse. But just how many universes are there? What are they like? And most importantly, what can they tell us about … aliens?

## Category: PBS Space Time

Space Time explores the outer reaches of space, the craziness of astrophysics, the possibilities of sci-fi, and anything else you can think of beyond Planet Earth with our astrophysicist host: Matthew O’Dowd.

## The Holographic Universe Explained

One of the most startling possibilities is that our 3+1 dimensional universe may better described as resulting from a spacetime one dimension lower – like a hologram projected from a surface infinitely far away.

## Computing a Universe Simulation

Imagine a universe in which the most elementary components are stripped of all properties besides some binary notion of existence or non-existence. Like, if the tiniest chunks of spacetime, or chunks of quantum fields, or elements in the abstract space of quantum-mechanical states can either be full or empty. These elements interact with their neighbors by a simple set of rules, leading to oscillations, elementary particles, atoms, and ultimately to all of the emergent laws of physics, physical structure, and ultimately the universe.

## How Much Information is in the Universe?

But… is the universe actually made of stuff? An increasing number of physicists view the universe – view reality as informational at its most fundamental level. But how big a memory bank would you even need to compute a universe? Seriously, let’s figure it out.

## How to Detect Extra Dimensions

On this Space Time Journal Club we look at how gravitational waves can be used to search for extra dimensions of space!

## Why String Theory is Wrong

There’s this idea that beauty is a powerful guide to truth in the mathematics of physical theory. String theory is certainly beautiful in the eyes of many physicists. Beautiful enough to pursue even if it’s wrong?

## Why String Theory is Right

Some see string theory as the one great hope for a theory of everything – that it will unite quantum mechanics and gravity and so unify all of physics into one glorious theory.

## What are the Strings in String Theory?

So surely there exists a deeper set of cogs and wheels – a theory that brings all observable phenomena into the same mechanical framework. That would be a theory of everything, and this is the great hope of string theory.

## The Geometry of Causality

In this episode we dive deeper into the relationship between space and time and explore how we can geometrically map the causality of the universe and increase our understanding of how time and distance relate to one another.