“Is our universe extremely unnatural, a strange permutation among countless other possibilities, observed for the sole reason that its special conditions allowed life to occur, or, are the properties of the universe unavoidable , predictable, i.e. ‘natural’, lock together in a sensible pattern?” This is the question, the great unknownwhich worries the theoretical physicist Nima Arkani-Hamedprofessor at the Institute for Advanced Study (IAS) in Princeton, NJ
Beyond spacetime and quantum physics
Arkani-Hamed takes us beyond the edge, beyond Einstein, beyond space-time and quantum mechanics and the tropes of 20th century physics, to a spectacular new view of the cosmos. In 2012, he won the first $3 million Fundamental Physics Prize “for original approaches to outstanding problems in particle physics, including proposing extra large dimensions, new theories for the Higgs boson, new realizations of supersymmetry, theories for dark matter and the exploration of new mathematical structures in the theory of gauge scattering amplitudes.
The “participatory universe”
Arkani-Hamed’s concern is the question that intrigued his predecessor, the great American quantum physicist Jean 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 we are all 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 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 instantly collapses into a single state.
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“Multiverse” of universes beyond our reach
A natural universe is, in principle, a knowable universe, written Beatrice de Géa in Quanta. But if the universe is not natural and suitable for life, observes Arkani-Hamed, “the lucky result 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 product of less fortuitous spins.This multiverse makes our universe impossible to fully understand on its own terms.
Amazingly refined for life
Known elementary particles, Béatrice de Géa concludes, codified in a 50-year-old set of equations called the “standard model”, lack a sensible model and seem surprisingly fine-tuned for life leading Arkani-Hamed and other physicists particles, guided by their belief in naturalness, spend decades devising clever ways to fit the Standard Model into a larger natural model, while particle colliders such as the Large Hadron Collider have failed to prove their proposals in the form of supersymmetry, new particles and phenomena, “pointing increasingly to the dark and radical perspective that the natural is dead”.
The fate of space-time
Today, many physicists feel trapped writing 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 feeling,” she writes, “that they need to transcend the notion that objects move and interact in space and time. Einstein’s theory of general relativity beautifully weaves space and time into a four-dimensional fabric, known as spacetime, and equates gravity with the deformations of this fabric. But Einstein’s theory and the concept of space-time collapse inside black holes and at the time of the big bang. Spacetime, in other words, may be a translation of another description of reality which, although more abstract or unfamiliar, may have greater explanatory power.
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Challenges space and time as fundamental components of reality
In 2013, Nima Arkani-Hamed and Jaroslav Trnka discovered a reformulation of scattering amplitudes that does not refer to space or time, rather they discovered that the amplitudes of certain particle collisions are encoded in the volume of a jewel-like geometric object they call an ‘amplituhedron’ that greatly simplifies calculations of particle interactions and challenges the notion that space and time are fundamental components of reality.
The amplituhedron, which seamlessly connects the large and small scale images of the universe, could help by removing two deeply rooted principles of physics: locality and unitarity. “Both are wired in the usual way we think about things,” Arkani-Hamed said. “Both are suspicious.”
This discovery led them to explore this new geometric formulation of particle scattering amplitudes, hoping that it will move away from our everyday, space-time-bound conception towards a “bigger” explanatory structure of reality. .
The unknown question – to which the universe is the answer
For Arkani-Hamed, the laws of nature suggest a different conception of what physics is. “We don’t build a machine that calculates answers,” he says, “instead, we uncover questions. Nature’s shape-shifting laws seem to be the answer to “an unknown mathematical question.”
“Ascension to the tenth level of intellectual heaven,” says Nima Arkani-Hamed, describing the ultimate goal of physics, “would be if we found the question to which the universe is the answer, and the nature of that question in and itself explains why it was possible to describe it in so many different ways.
“It now seems that the answers surround us. This is 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 Quant. Avi was previously a NASA Sagan Fellow at the Jet Propulsion Laboratory (JPL)
Image credit: Shutterstock License
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Avi Sporer, Research Scientist, MIT Kavli Institute for Astrophysics and Space Research. Google Scholar, Avi was previously a NASA Sagan Scholar at the Jet Propulsion Laboratory (JPL). His motto, unsurprisingly, is a quote from Carl Sagan: “Somewhere, something amazing is waiting to be known.”
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