I recently had the pleasure of reading QBism - The Future of Quantum Physics by Hans Christian von Bayer, after stumbling upon the topic through this blog post by Wired. Though I’ve taken to listening to audiobooks or reading on my iPad, Reading a physical copy of this book was quite enjoyable. I felt focused and undisturbed, and the weight of the hardcover binding gave me the feeling I was reading something real. As for the ideas contained within the little yellow book, Professor von Bayer’s style of writing is crisp and enjoyable. He does not delve into any math, instead opting to devote all of his inktime to the subjective interpretation of quantum theory. Needless to say, I really liked the book.

According to QBism (formerly known as Quantum Bayesianism), the wavefunction is not real. It exists in the mind of each and every observer, as opposed to out there in the world. The wavefunction never physically collapses, but rather can be viewed as the moment in your mind when your belief about your surroundings changes. For those familiar with Schrödinger and his cat: the wavefunction does not insist that the poor cat is both dead and alive; it merely provides us with a prior on what one might find were they to open the box.

The map is not the territory.

However, the wavefunction’s unreality is not to say that the world is not real. One of the key insights of QBism is its delineation between subject and object, sharply illustrated by the above quote. The objective is everything that takes place outside of each of our minds, while the subjective is what happens inside the mind.

I find the QBist interpretation of quantum mechanics calming. On a personal level, it makes me feel important - like I’m in the driver’s seat instead of just a passenger.