Ant-Man and the Physics of the Impossible

Ant-Man and the Wasp is an entertaining, fun-filled film, even if its artistic freedom bends its scientific accuracy at times. Nevertheless, and quite surprisingly, there are some physics lessons to be learned from it, especially with regards to the strange laws of quantum theory. It succeeds in doing so by clearly separating between small things and really small things.

As we observe the world around us, we intuitively understand that there is a causal relationship between action and outcome, and we can therefore predict or direct what will happen next. For instance, if someone throws a ball towards us (action), we can predict where the ball will go (outcome) and catch it. Similarly, when basketball players shoot for the hoop, they know exactly which force and direction are needed to score. Actually, building a machine that would always goal is possible: if it exerts the appropriate force on the ball in the right direction, and all other conditions remain the same, it will never miss.

In more scientific terms, we can say that a ball's initial conditions (i.e., speed and direction at the moment it is thrown, together with the environmental conditions) allow us to predict exactly where it will go. This perspective, in which knowing the initial conditions enables us to predict the final outcome, is called determinism – namely, the past completely determines the future. The classical laws of physics were formulated according to this approach, from the days of Newton up until the early 20^th century. 

The physics of small things

All of this holds true for the things that we can see and feel directly with our senses. But what happens when we look at much smaller things?

The first scientific lesson to be learned from Ant-Man and the Wasp is that at very small scales, the laws of reality change. As long as Ant-Man is working at a scale that we can still see and perceive – shrinking to the size of an ant, for instance – the laws or reality as we know them still hold. Even at this size, a prediction can still be made (intuitively) as to where a knife thrown at him at a certain speed and direction will hit, and thus avoid it. However, when he shrinks down even more, to the size of the most fundamental particles, the movie visually demonstrates, fairly correctly, that the laws of nature change substantially.  

First, we must understand what "small" means. The building blocks of matter are called atoms, which have a size of no more than one tenth of a billionth of a meter. This is a million times smaller than a size that can be observed with a naked human eye. The magnificent thing is that when we examine single atoms or small groups of connected atoms (molecules), and of course, if we examine even smaller particles, our entire understanding of the world changes. The laws that apply to these tiny particles are very different from those that apply to the world that is familiar to us. The system of rules that describes small objects is called quantum theory.

What are the laws of physics of the small world? It appears that, in contrast to basketball, for instance, even if we know a given atom's initial conditions, we still cannot know for certain where it will go in the future. We can only know that there is a certain probability for it to reach one place, and a different probability to reach another.

This is a significant and profound difference between quantum physics and classical physics. Quantum theory describes precisely how to calculate the probability that an atom will go to any given point, but cannot determine what will be the actual outcome. The situation becomes even stranger – not only do we not know for certain where the atom will go, as long as we did not measure it – namely, did not check to see where it went – it is at all possible locations at once. Sounds strange, doesn't it? And yet, many experiments conducted to date corroborate the predictions of quantum theory, and they turned out to be incredibly accurate across all of them.

Fits like a glove to an Ant-Man

Another quantum phenomenon that the film’s creators managed to more-or-less depict accurately was the connection they created between Ant-Man and the “Wasp's” mother, who was also stuck in quantum reality. This relationship was constructed so that the moment something happened to her, it also affected Ant-Man. This is an artistic demonstration of a concept called "quantum entanglement", which was demonstrated in many experiments on the minute particles to which quantum theory applies.

Quantum entanglement is a situation in which two small objects, such as atoms, are connected to one another in such a way that if we know the state of one, we will immediately know the state of the other. This can be compared to a pair of gloves: If we were to give each glove to a different person, the one who received the left glove would immediately know that the other has the right glove.

In the quantum world, two objects can be connected so that knowledge about one immediately tells us something about the other. This may sound trivial, until you realize, once again, that a quantum particle does not have defined properties until it is measured. Due to this fact, measuring one entangled particle can immediately impact its counterpart, even if it very far away, without any information transmitted between the two, or time to transmit such information.

This result, demonstrated in numerous experiments, seemed so absurd that in the famous 1935 paper by Albert Einstein, Boris Podolsky, and Nathan Rosen, the authors claim that quantum theory should be updated to not allow such phenomena! In practice, what was eventually updated was not the theory, but the way we understand reality.

One of physics’ most fascinating questions, which we still do not completely know how to answer, is when and how does the transition between the quantum world and the world we are familiar with take place. It is true that quantum physics only describes very small objects, but any large object is actually constructed from atoms and molecules. How is it that combining enough of them together makes the world behave according to more "reasonable" rules of cause-and-effect? For instance, how is it that a basketball, constructed of trillions of atoms, to each of which quantum physics applies, behaves in a manner that classical physics knows how to describe?

The answer is most likely that the "large" reality is the average reaction of all tiny quantum phenomena. It seems you really need to be Ant-Man in order to deal with all the strange rules of the really small things.

Translated by Elee Shimshoni