In One Universe, the Cat Dies

How the uncertain fate of a fictional tabby gave us the multiverse.

Did you know it was the fate of a solitary (imaginary) kitty that led quantum theoreticians—in particular one Hugh Everett III—to the idea of multiple universes? The theoretical cat belonged to Austrian physicist Erwin Schrödinger. Physics professor Jim Kakalios of the University of Minnesota tells the story in this video.


Schrödinger’s Cat is a famous mind experiment that goes like this. Schrödinger imagined a box into which have been placed three things:

1. a single radioactive isotope

2. a sealed bottle of poisoned gas

3. a cat

The isotope has a half-life of an hour, which means that 50% of the time, the pretend isotope will decay in an hour, releasing an imaginary alpha particle that breaks the bottle and kills the fictional cat. 50% the time, that kitty will be fine.

After one hour, you’ll open the box to learn the fate of the cat. The mathematical way to describe the cat before you look is an average of a living kitty and a dead kitty, which makes no sense really, zombies notwithstanding.

To avoid such a nonsensical idea, Schrödinger posited that until you look, the cat exists simultaneously in two quantum states, one living and one dead. It’s only upon opening the box and looking that one or the other state comes true. (Is this different than believing you don’t have cancer until the doctor tells you you do?)

Anyway, this was too much for Everett to buy, and he proposed instead that when the box is closed, the two possible outcomes split off into two quantum states, each in its own parallel universe, one where the cat lives and one where the cat dies. In a different situation with more than two possible outcomes, each outcome would exist in its own quantum state, and thus its own universe—and so bam, welcome to the multiverse. Everett suggested that when we open the box and look, all that really happens is we learn which of the two living/dead cat universes we happen to be in.

Which makes so much more sense?

On the other hand, it’s nothing any devoted Fringe fan doesn’t know.

Big Think
Sponsored by Lumina Foundation

Upvote/downvote each of the videos below!

As you vote, keep in mind that we are looking for a winner with the most engaging social venture pitch - an idea you would want to invest in.

Keep reading Show less

Why Lil Dicky made this star-studded Earth Day music video

"Earth" features about 30 of the biggest names in entertainment.

Culture & Religion
  • Lil Dicky is a rapper and comedian who released his debut album in 2015.
  • His new music video, "Earth," features artists such as Justin Bieber, Ariana Grande, Ed Sheehan, Kevin Hart, and Leonardo DiCaprio.
  • All proceeds of the music video will go to environmental causes, Dicky said.
Keep reading Show less

After death, you’re aware that you’ve died, say scientists

Some evidence attributes a certain neurological phenomenon to a near death experience.

Credit: Petr Kratochvil. PublicDomainPictures.net.
Surprising Science

Time of death is considered when a person has gone into cardiac arrest. This is the cessation of the electrical impulse that drive the heartbeat. As a result, the heart locks up. The moment the heart stops is considered time of death. But does death overtake our mind immediately afterward or does it slowly creep in?

Keep reading Show less

Behold, the face of a Neolithic dog

He was a very good boy.

Image source: Historic Environment Scotland
Surprising Science
  • A forensic artist in Scotland has made a hyper realistic model of an ancient dog.
  • It was based on the skull of a dog dug up in Orkney, Scotland, which lived and died 4,000 years ago.
  • The model gives us a glimpse of some of the first dogs humans befriended.
Keep reading Show less