From Quanta Mag ( find original story hither ).

"Insanity is doing the same thing over and over and expecting different results."

That witticism—I'll telephone call it "Einstein Insanity"—is usually attributed to Albert Einstein. Though the Matthew effect may be operating hither, information technology is undeniably the sort of clever, memorable one-liner that Einstein often tossed off. And I'yard happy to give him the credit, because doing so takes us in interesting directions.

First of all, note that what Einstein describes as insanity is, co-ordinate to quantum theory, the way the globe actually works. In quantum mechanics you can do the aforementioned thing many times and become different results. Indeed, that is the premise underlying great high-energy particle colliders. In those colliders, physicists fustigate together the same particles in precisely the aforementioned style, trillions upon trillions of times. Are they all insane to do so? Information technology would seem they are not, since they take garnered a stupendous variety of results.

Of course Einstein, famously, did non believe in the inherent unpredictability of the world, maxim "God does not play die." Still in playing dice, we act out Einstein Insanity: We do the aforementioned thing over and over—namely, ringlet the dice—and we correctly conceptualize dissimilar results. Is it really insane to play dice? If then, it's a very common form of madness!

We can evade the diagnosis past arguing that in practice i never throws the dice in precisely the aforementioned way. Very small changes in the initial conditions can alter the results. The underlying idea here is that in situations where we tin can't predict precisely what's going to happen next, it's because there are aspects of the electric current situation that we haven't taken into account. Similar pleas of ignorance can defend many other applications of probability from the accusation of Einstein Insanity to which they are all exposed. If we did take full access to reality, according to this argument, the results of our actions would never exist in doubt.

This doctrine, known as determinism, was advocated passionately by the philosopher Baruch Spinoza, whom Einstein considered a great hero. Simply for a meliorate perspective, we demand to venture even further dorsum in history.

Parmenides was an influential aboriginal Greek philosopher, admired by Plato (who refers to "male parent Parmenides" in his dialogue the Sophist). Parmenides advocated the puzzling view that reality is unchanging and indivisible and that all movement is an illusion. Zeno, a student of Parmenides, devised iv famous paradoxes to illustrate the logical difficulties in the very concept of motion. Translated into modern terms, Zeno's arrow paradox runs as follows:

  1. If you know where an arrow is, you know everything about its physical state.
  2. Therefore a (hypothetically) moving pointer has the same physical state equally a stationary pointer in the aforementioned position.
  3. The electric current concrete land of an arrow determines its future concrete state. This is Einstein Sanity—the denial of Einstein Insanity.
  4. Therefore a (hypothetically) moving arrow and a stationary arrow have the same future physical state.
  5. The arrow does not move.

Followers of Parmenides worked themselves into logical knots and mystic raptures over the rather breathy contradiction between point 5 and everyday experience.

The foundational achievement of classical mechanics is to establish that the first point is faulty. Information technology is fruitful, in that framework, to allow a broader concept of the character of physical reality. To know the land of a system of particles, one must know not only their positions, but too their velocities and their masses. Armed with that information, classical mechanics predicts the system'south future evolution completely. Classical mechanics, given its broader concept of physical reality, is the very model of Einstein Sanity.

With that triumph in mind, allow us render to the apparent Einstein Insanity of quantum physics. Might that difficulty also hint at an inadequate concept of the state of the world?

Einstein himself thought so. He believed that at that place must be hidden aspects of reality, not still recognized inside the conventional conception of breakthrough theory, which would restore Einstein Sanity. In this view information technology is non so much that God does non play dice, simply that the game he'southward playing does not differ fundamentally from classical dice. It appears random, but that's only because of our ignorance of certain "hidden variables." Roughly: "God plays dice, but he'south rigged the game."

Only as the predictions of conventional quantum theory, free of hidden variables, have gone from triumph to triumph, the wiggle room where one might accommodate such variables has get minor and uncomfortable. In 1964, the physicist John Bong identified sure constraints that must apply to any physical theory that is both local—meaning that physical influences don't travel faster than lite—and realistic, pregnant that the physical properties of a system be prior to measurement. Merely decades of experimental tests, including a "loophole-free" test published on the scientific preprint site arxiv.org final month, show that the world we live in evades those constraints.

Ironically, conventional quantum mechanics itself involves a vast expansion of physical reality, which may be enough to avoid Einstein Insanity. The equations of breakthrough dynamics allow physicists to predict the future values of the wave role, given its present value. Co-ordinate to the Schrödinger equation, the wave function evolves in a completely predictable way. Only in practise we never have access to the total moving ridge office, either at nowadays or in the time to come, so this "predictability" is unattainable. If the wave function provides the ultimate description of reality—a controversial issue!—we must conclude that "God plays a deep yet strictly rule-based game, which looks like dice to united states."

Einstein's not bad friend and intellectual sparring partner Niels Bohr had a nuanced view of truth. Whereas according to Bohr, the contrary of a simple truth is a falsehood, the contrary of a deep truth is another deep truth. In that spirit, allow us introduce the concept of a deep falsehood, whose opposite is likewise a deep falsehood. Information technology seems fitting to conclude this essay with an epigram that, paired with the one nosotros started with, gives a nice example:

"Naïveté is doing the aforementioned affair over and over, and always expecting the aforementioned result."

Frank Wilczek was awarded the 2004 Nobel Prize in physics for his work on the theory of the strong force. His most recent book is A Cute Question: Finding Nature's Deep Design. Wilczek is the Herman Feshbach Professor of Physics at the Massachusetts Constitute of Technology.

Reprinted with permission from Quanta Mag, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.