What is Big Think?  

We are Big Idea Hunters…

We live in a time of information abundance, which far too many of us see as information overload. With the sum total of human knowledge, past and present, at our fingertips, we’re faced with a crisis of attention: which ideas should we engage with, and why? Big Think is an evolving roadmap to the best thinking on the planet — the ideas that can help you think flexibly and act decisively in a multivariate world.

A word about Big Ideas and Themes — The architecture of Big Think

Big ideas are lenses for envisioning the future. Every article and video on bigthink.com and on our learning platforms is based on an emerging “big idea” that is significant, widely relevant, and actionable. We’re sifting the noise for the questions and insights that have the power to change all of our lives, for decades to come. For example, reverse-engineering is a big idea in that the concept is increasingly useful across multiple disciplines, from education to nanotechnology.

Themes are the seven broad umbrellas under which we organize the hundreds of big ideas that populate Big Think. They include New World Order, Earth and Beyond, 21st Century Living, Going Mental, Extreme Biology, Power and Influence, and Inventing the Future.

Big Think Features:

12,000+ Expert Videos


Browse videos featuring experts across a wide range of disciplines, from personal health to business leadership to neuroscience.

Watch videos

World Renowned Bloggers


Big Think’s contributors offer expert analysis of the big ideas behind the news.

Go to blogs

Big Think Edge


Big Think’s Edge learning platform for career mentorship and professional development provides engaging and actionable courses delivered by the people who are shaping our future.

Find out more
With rendition switcher


Question: What does “Schrödinger’s cat” teach us about the concept of a multiverse?

Jim Kakalios: If I have a radioactive isotope and I say it has a half life of a year, what that means is that after a year, there’s a 50% chance that it decays or a 50% chance that it doesn’t decay. And if I have a million isotopes after a year, sure enough I’ll have half a million. However, I don’t know which half will have decayed until the year is up, but I can predict accurately that roughly half of them will go.

Well Schrödinger said, well what about if I had not a million isotopes, but one isotope? Let’s say it has a half-life of an hour. If it decays, it will emit an alpha particle, that alpha particle will break open a bottle of poisoned gas and the poisoned gas can kill a cat that we put inside a box. It’s not like we physicists hate cats, but you may argue that the process of observing the radioactive isotope changes whether it decays or doesn’t decay, but few people would say, looking at a cat, changes whether it’s alive or dead. So it’s a way of amplifying a microscopic event to something macroscopic.

You put the cat in the box, you close the lid, after an hour, you open it up. Quantum mechanics says that there’s a 50% chance that the isotope has decayed in which case it has emitted a particle and the cat has died. But a 50% chance it doesn’t decay in which case we would find a live cat. Until you open the box, the only way to describe the cat is in an average of half alive and half dead. This sounds so stupid that we use different language. There’s linear superposition of two orthogonal quantum states. But, basically it’s saying it’s half alive, half dead.

And when we open up the box, the wave function collapses into either one situation, all alive, or another situation, all dead. As strange as this sounds, recent experiments involving entangled quantum states seem to suggest that this is in fact what happens.

But in 1957, Hugh Everett III, part of his PhD thesis at Princeton, proposed an alternative explanation. He said there was no average of half alive, half dead, no collapsing wave functions. What happened was that was when we closed up the box initially we split off two parallel universes. And at the end of the hour, the wave functions don’t collapse, all we do is discover—do we live in a universe where the cat lived or the universe where the cat died? And for every quantum event that has two outcomes, there’s at least that many universes. So there is in principle and infinite number of parallel universes.

Needless to say, physicists did not consider this helpful. And these ideas, which had been later on described by Brice DeWitt as the many worlds interpretation of quantum mechanics had been considered kind of like the crazy aunt of quantum theory and ignored up until fairly recently. But String Theorists and other physicists trying to develop a quantum theory of gravity have found that they needed to dust off the many worlds interpretation and apply it to their theories in order to make them work out.

More from the Big Idea for Friday, January 25 2013

Quantum Theory

Our deepest understanding of the atomic world comes from the advent of quantum theory. The theory itself underlies the entire architecture of the world we see today and beyond. It has ultimately a... Read More…


What Dead Cats Tell Us Abou...

Newsletter: Share: