Imagine you met a girl at a barbeque who asked you to lick your elbow. Would you try it? Would you make an excuse to get away? What if you did both at precisely the same time?
Using ideas from quantum physics and cosmology, the play Constellations addresses the universal question, what if? What would our lives be like if we had made a different choice? If we said the same words slightly differently? This is the story of a cosmologist named Marianne (Ginnifer Goodwin) and Roland, a bee keeper (Allen Leech) and every decision they ever and never made.
Set against a simple black background with globes of light hanging at different heights, the audience watches as Marianne and Roland meet, and then meet again… and again. As the scene repeats, each slightly or completely different from the one before it, the color of the globes of light changes. In one moment the awkwardness of Marianne and Roland’s interaction is excruciating, but with a simple shift in color, their glances turn interested, the attraction palpable.
Through a series of these repeated vignettes, Marianne and Roland’s relationship develops, ends, or simply never begins. With every shift in the light, a new story unfolds in what seems like a parallel universe. In a scene in her apartment, Marianne describes this idea of multiple universes as she tells Roland about her cosmology research. Multiple universes can exist all at once, she explains, where every possibility plays out at exactly the same time. It is this concept of multiple universes that defines the structure of Constellations as Marianne and Roland’s many possible futures play out.
The idea of the existence of multiple universes – or the multiverse – has fascinated and frustrated physicists for years. Many scientists are skeptical of the existence of multiple universes because so far there is no way to prove that they exist . According to the scientific method, a hypothesis must be testable in order to prove or disprove it. However, research in quantum mechanics and recent observations of the night sky have led to the development of new theories that suggest one day we may be able to test for the existence of a multiverse.
One theory of the multiverse is based in quantum mechanics, which describes the physical world at very small scales, at the level of subatomic particles like electrons and protons. At these tiny scales, matter behaves as both a particle and a wave, which makes determining the precise location of one of these particles somewhat difficult. However, we can think of their wave properties as the probability of finding the particle at any one point in space, a concept called the wave-function (ψ) . Once the location of the particle is measured or observed, the wave-function is said to “collapse” because now the actual location of the particle is known; it is no longer defined by a probability.
Schrödinger illustrated this idea and its limitations to events on the quantum scale in his famous cat thought-experiment . In this situation, a cat is placed in a box with a decaying radioactive atom and a vial of poison . If the radioactive atom decays, a probabilistic event, it will trigger the release of the poison, killing the cat. However, it is equally likely that the atom will not decay, and the cat will remain alive. Thus, according to the wave-function for this scenario, before you open the box and observe it, the cat is both alive and dead. This concept is called superposition because both of the alive and dead states are equally probable . It is only after the box is opened and the cat is observed that the wave-function collapses and the cat’s fate is determined.
So, how does this both-dead-and-alive-cat relate to the existence of a multiverse? The answer comes down to Hugh Everett III, who suggested that upon observation or measurement of a particle, the wave-function does not necessarily need to collapse . Instead, once the observer opened the box, they would enter the same superposition as the cat . The situation would split in two with one observer seeing a dead cat and the other seeing a live cat. All of the possibilities described by the wave-function would branch off on their own independent paths . This idea was given the name the “Many Worlds” interpretation because each choice or branch point would fractionate into its own future, its own universe.
A second theory of the multiverse is based on Inflation theory from the field of cosmology, Marianne’s research area. To understand how Inflation leads to a multiverse, we need to go back to the very beginning of our universe as we know it: the Big Bang. Fractions of a second after the Big Bang, the universe underwent a phase of rapid expansion followed by a cooling period, which allowed elementary particles to come together to form atoms, which then came together to form stars and galaxies . But what caused this initial expansion? Inflation theory suggests that a small patch of “repulsive gravity” initiated the Big Bang and the resulting expansion of the universe .
Typically, we think of gravity as something attractive as Marianne demonstrates by letting go of a pillow so it drops to the floor, pronouncing “gravity!” However, in his General Theory of Relativity, Einstein predicted that at very high energies, a form of matter would exist that would be gravitationally repulsive . This repulsive gravity pushed the universe apart at an exponential rate, but because repulsive gravity is unstable, not all regions of the universe may have stopped expanding at the same time . Meaning that, these regions where inflation has stopped result in the generation of “pocket universes,” thus leading to the existence of a multiverse [7, 8]. Physicists think that if pocket universes exist, they may have had the opportunity to collide with one another. In doing so, they would have left a mark on our observable universe, like two soap bubbles colliding in the air . Intriguingly, recent observations of the Cosmic Background Radiation, heat left over from the Big Bang, lend support to this hypothesis .
Whether these ideas of a multiverse from quantum mechanics or cosmology one day prove to be true or simply remain untestable predictions of the laws of physics, they provide us with a way to think about how we fit in our universe. How do our choices change the trajectory of our lives and how we move through our world? Portraying Roland and Marianne’s joyous and devastating realities in parallel, Constellations uses the beauty of physics to tell a truly human story of love, loss, and infinite possibilities.
Constellations is currently running at the Geffen Playhouse in Los Angeles, CA through July 23, 2017. Visit http://www.geffenplayhouse.org/constellations for tickets and more information.
Stephanie DeMarco (@sci_steph)
Editor-in-Chief, Signal to Noise Magazine
Molecular Biology PhD Candidate, UCLA
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 Tegmark, M. & Wheeler, J. A. 100 Years of Quantum Mysteries. Scientific American, 68-75 (2001, Feb).
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 Everett III, H. “Relative State” Formulation of Quantum Mechanics. Reviews of Modern Physics 29(3), 454-462 (1957).
 Orzel, C. What The Many-Worlds Interpretation of Quantum Physics Really Means. Forbes (2016, Jan 5). https://www.forbes.com/sites/chadorzel/2016/01/05/what-the-many-worlds-interpretation-of-quantum-physics-really-means/#37826d711028
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