One of the most deeply rooted concepts in science and in our
everyday life is causality; the idea that events in the present are caused by
events in the past and, in turn, act as causes for what happens in the future.
If an event A is a cause of an effect B, then B cannot be a cause of A. Now
theoretical physicists from the University of Vienna and the Université Libre
de Bruxelles have shown that in quantum mechanics it is possible to conceive
situations in which a single event can be both, a cause and an effect of another
one. The findings will be published this week in "Nature
Communications".
Although it is still not known if such situations can be
actually found in nature, the sheer possibility that they could exist may have
far-reaching implications for the foundations of quantum mechanics, quantum
gravity and quantum computing.