Quantum physics depends on observers selecting how and where measurements are obtained–unlike classical physics which has no such requirement for an observer.
The idea of observation and the role of the “Observer” are key to the study of quantum mechanics, since the selection of how and where a measurement is made affects what is subsequently observed. There is a special meaning to the word ‘Observer’ in quantum physics, in which selection of a method of measurement of a quantum system influences what is subsequently observed. Methods of measurement include people at some point, so we play the role of Observer when we choose what we look at and how we look at the world.
This aspect of quantum physics is sometimes referred to as “the observer effect” and “the measurement problem.” The so-called ‘measurement problem’ is related to the Observer and has been called the most controversial problem in physics today, because in the realm of Quantum Mechanics, there appears to be no singular fixed reality that is exists when nobody is looking.
Intriguingly, there can exist layers upon layers of observers–such that it can be possible for someone observing an observer to ultimately influence events–such as Schrodinger observing a cat inside a box of poison (such that the cat can be envisioned to be existing in some state of being both alive and dead)–or someone observing someone observing the cat inside the box with the poison.
Many physicists have recently been discussing the idea of quantum steering–of how one observer might be able to influence the outcome of an experiment being observed by another observer. The concept of quantum steering, or EPR-steering, was first proposed by physicist Erwin Schrodinger as a thought experiment in which remote observers of a quantum system share entangled particles. In such a scenario one observer might then be able to direct–or steer–the state of another’s system when performing a measurement on their system.
In hypothetical experimental quantum steering situations, one individual who is often called “Alice” for purposes of these discussions might influence the observations of of a quantum system by another observer, “Bob.” Related areas of research involve determining if this kind of influence is one-sided; whether Bob can tell when he is being influenced; whether such influence can occur even if Alice is known to Bob as ‘untrustworthy’; and how strong such influence might be.
What I find especially intriguing about these topics at the dawn of this new Quantum Age is awareness of ways that each of us actually can remotely influence others we are entangled with.
Turtles All the Way Down
Once we recognize the possibility that each observer’s questions–and subsequent measurements–can influence what is happening, we come to realize we’ve entered into a situation where someone observing someone observing can have an effect on the outcome of what is being observed. This concept was popularized by the physicist Eugene Wigner, who presented a variation of Schrodinger’s cat thought experiment, “Wigner’s Friend,” in which an observer watches an observer of a cat enclosed in a box with a vial of poison that could be released by a quantum mechanism–thus trapping this hypothetical feline in a state of quantum superposition–of being simultaneously alive and dead.
The issue in this case of observers influencing other observers’ observations is that it’s easy to see how there might be no end to the chain of observations. We thus can find ourselves in the unenviable position of not really knowing the ‘true observer’ of an event.d
These topics are important because some of the most interesting conversations getting to the heart of consciousness recently are happening where multi-disciplinary fields of science meet technology to create artificial intelligence and quantum computing. Such discussions are necessary for designing how our next generations of computers and robots will operate.
You can watch the companion video to this blog post at: