“Is our universe extremely unnatural, a weird permutation among countless other possibilities, observed for no other reason than that its special conditions allowed life to arise, or, are the properties of the universe are inevitable, predictable, that is, ‘natural,’ locking together into a sensible pattern?” This is the question, the great unknown, that preoccupies theoretical physicist Nima Arkani-Hamed, a professor at the Institute for Advanced Study (IAS) in Princeton, N.J.
Beyond Spacetime and Quantum Physics
Arkani-Hamed takes us past the edge, beyond Einstein, beyond space-time and quantum mechanics and the tropes of 20th-century physics, to a spectacular new vision of the cosmos. In 2012, he won the inaugural $3 million Fundamental Physics Prize “for original approaches to outstanding problems in particle physics, including the proposal of large extra dimensions, new theories for the Higgs boson, novel realizations of supersymmetry, theories for dark matter, and the exploration of new mathematical structures in gauge theory scattering amplitudes.”
The “Participatory Universe”
Arkani-Hamed’s preoccupation is the question that intrigued his predecessor, the great American quantum physicist John Archibald Wheeler in the last decades of his life was: “Are life and mind irrelevant to the structure of the universe, or are they central to it?” Wheeler originated the notion of a “participatory,” conscious universe, a cosmos in which all of us are embedded as co-creators, replacing the accepted universe “out there,” which is separate from us. He suggested that the nature of reality was revealed by the bizarre laws of quantum mechanics. According to the quantum theory, before the observation is made, a subatomic particle exists in several states, called a superposition (or, as Wheeler called it, a ‘Smoky Dragon’). Once the particle is observed, it instantaneously collapses into a single state.
“Multiverse” of Universes Beyond Our Reach
A natural universe is, in principle, a knowable one, writes Béatrice de Géa in Quanta. But if the universe is unnatural and fine-tuned for life, observes Arkani-Hamed, “the lucky outcome of a cosmic roulette wheel, then it stands to reason that a vast and diverse “multiverse” of universes must exist beyond our reach — the lifeless products of less serendipitous spins. This multiverse renders our universe impossible to fully understand on its own terms.
Astonishingly Fine-tuned for Life
The known elementary particles, concludes Béatrice de Géa, codified in a 50-year-old set of equations called the “Standard Model,” lack a sensible pattern and seem astonishingly fine-tuned for life leading Arkani-Hamed and other particle physicists, guided by their belief in naturalness, to spend decades devising clever ways to fit the Standard Model into a larger, natural pattern while particle colliders such as the Large Hadron Collider have failed to turn up proof of their proposals in the form of supersymmetry, new particles and phenomena, “increasingly pointing toward the bleak and radical prospect that naturalness is dead.”
The Doom of Spacetime
Today, many physicists feel trapped writes Natalie Wolchover in The New Yorker, and see the need to reformulate the theories of modern physics in a new mathematical language. “They have a hunch,” she writes, “that they need to transcend the notion that objects move and interact in space and time. Einstein’s general theory of relativity beautifully weaves space and time together into a four-dimensional fabric, known as space-time, and equates gravity with warps in that fabric. But Einstein’s theory and the space-time concept break down inside black holes and at the moment of the big bang. Space-time, in other words, may be a translation of some other description of reality that, though more abstract or unfamiliar, can have greater explanatory power.”
Challenges Space and Time as Fundamental Components of Reality
In 2013, Nima Arkani-Hamed and Jaroslav Trnka discovered a reformulation of scattering amplitudes that makes reference to neither space nor time, rather they discovered that the amplitudes of certain particle collisions are encoded in the volume of a jewel-like geometric object, which they named the “amplituhedron” that dramatically simplifies calculations of particle interactions and challenges the notion that space and time are fundamental components of reality.
The amplituhedron, seamlessly connects the large- and small-scale pictures of the universe, could help by removing two deeply rooted principles of physics: locality and unitarity. “Both are hard-wired in the usual way we think about things,” said Arkani-Hamed. “Both are suspect.”
This discovery has led them to explore this new geometric formulation of particle-scattering amplitudes, hoping that it will lead away from our everyday, space-time-bound conception to some “grander” explanatory structure of reality.
The Unknown Question –To Which the Universe is the Answer
To Arkani-Hamed, the laws of nature suggest a different conception of what physics is all about. “We’re not building a machine that calculates answers,” he says, “instead, we’re discovering questions. Nature’s shape-shifting laws seem to be the answer ”to an unknown mathematical question”.
“The ascension to the tenth level of intellectual heaven,” says Nima Arkani-Hamed, describing the ultimate goal of physics, “would be if we find the question to which the universe is the answer, and the nature of that question in and of itself explains why it was possible to describe it in so many different ways.”
“It now appears that the answers surround us. It’s the question we don’t know.”
Avi Shporer, Research Scientist, MIT Kavli Institute for Astrophysics and Space Research, via Institute for Advanced Studies, The New Yorker and Quanta. Avi was formerly a NASA Sagan Fellow at the Jet Propulsion Laboratory (JPL)
Image credit: ESA the early Universe