A Problem with Causation in Quantum Physics

Full story and credits

aliceandbob

You may have heard of the double-slit experiment, in which a single particle fired at two small gaps appears to interfere with itself, as if it had passed through both slits at once. That happens because, until it is measured by a detector on the other side, the particle is in a quantum superposition of two states. In some sense it is able to take both paths.

It’s weird, and difficult to wrap your head around, but now a team at the University of Vienna in Austria have performed a different kind of experiment that is even more mind-bending: putting the order of events into a superposition.

Normally, it’s easy for us to say that event A happens before event B, or vice versa. But Giulia Rubino and her colleagues have created a situation in which these seemingly contradictory scenarios are in superposition. “If you put together quantum mechanics and causal relations, a situation arises in which there is no pre-defined causal order,” she says. “It’s counter-intuitive.”

Continues . . . . 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s