Three scientists have won $100,000 for their work on new ways to study the large-scale structure of the universe — the enormous tendrils of criss-crossing matter which hide evidence of our universe’s fundamental forces.
Mikhail Ivanov, of MIT, Oliver Philcox, of Columbia University and the Simons Foundation, and Marko Simonović, of the University of Florence, won the New Horizons Prize in Physics “for contributions to our understanding of the large-scale structure of the universe and the development of new tools to extract fundamental physics from galaxy surveys.”
The New Horizons award is given each year to early career researchers by the Breakthrough Prize Foundation, and the prize money is donated by tech billionaires Sergey Brin, Priscilla Chan and Mark Zuckerberg, Yuri and Julia Milner, and Anne Wojcicki. A second prize was also awarded this year to Alexandru Lupsasca, of Vanderbilt University, and Michael Johnson, of Harvard University for their work chasing mysterious black hole photon spheres.
Inside the cosmological collider
According to the standard model of cosmology, the universe began taking shape after the Big Bang, when the young cosmos swarmed with particles of both matter and antimatter, which popped into existence only to annihilate each other upon contact. Most of the universe’s building blocks wiped themselves out this way. If they had done so completely, no galaxies, stars, or planets would have formed.
Yet the universe was saved by tiny perturbations in the rapidly expanding fabric of space-time, which enabled some pockets of the plasma to survive. As the roiling particle-antiparticle broth of the young cosmos expanded, its molten filaments moved outwards to form an interconnected soap-sud structure of thin films surrounding countless, mostly empty voids.
Today, the universe exists as a map of those earliest particle interactions, which are frozen in time along strands and structures of an enormous cosmic web (today the birthing grounds of galaxies such as our own). This web’s form hints at the mysterious, primordial forces that shaped it.
“If you imagine taking the Large Hadron Collider at CERN and scaling it up by a factor of a trillion or a trillion trillions, this is the sort of particle collider that you actually have operating in the early Universe,” Oliver Philcox, told Live Science. “And anything weird that happens, it’s going to affect the distribution of matter.”
Detecting where matter was just after the Big Bang can reveal early particle interactions that occurred during the inflation that followed, a moment when the universe expanded exponentially fast for a mere fraction of a second. If we view the galaxies as the petrified remains of these earliest moments, we can search for hints of particle physics in the super early universe, Philcox said.
“So it is sometimes called the ‘cosmological collider’ — like a particle collider on the scale of the whole universe,” Philcox added.
Until recently, owing to both theoretical as well as experimental limitations, physicists studying how our universe evolved mainly focused on the Cosmic Microwave Background (CMB) — the leftover radiation from the Big Bang that exists as a 2D image burned into every corner of the sky. This can be explained by a simple theorem, only including linear terms, called cosmological perturbation theory.
However, a growing ability to map the universe’s cosmic web and a desire to understand mysterious phenomena such as dark matter and dark energy (neither of which are explained by current cosmology) has driven physicists to look at the large scale structures of the web directly.
Dot-mapping a cosmic hurricane
Yet astronomical cartography on these structures enormous is hard. Galaxies are produced by complicated astrophysical processes sculpted by the universe’s expansion and the collapse of its matter.
For instance, when large structures get close to each other, non-linear effects such as virialization (when gravitational objects spiral into a stable orbit) take hold. When they are far away, relativistic effects from the expansion of the universe warp space-time, also disrupting linear equations.
“A good analogy could be water waves. If our universe is an ocean, the CMB fluctuations are tiny ripples on its surface. A galaxy then would be a tsunami, or a hurricane,” Mikhail Ivanov told Live Science. “Water ripples can be easily described within basic fluid dynamics developed centuries ago. This is, in essence, cosmological perturbation theory. A hurricane is impossible to describe with pen and paper, we can run some expensive computer simulations for it, but they are highly uncertain.”
To skirt these mathematical headwinds, the researchers have been contributing to a theory called effective field theory (EFT) for large scale structures, as well as building several statistical tools that will help them analyze how galaxies interact.
As linear equations to describe the early universe break down at both ends of the cosmic scale, EFT smooths out the picture by simplifying galaxies as dots, and viewing their positions in the cosmos at just the right distance for our two best descriptions of gravity (Newtonian mechanics and general relativity) to be applicable with only minor adjustments.
Theorists working on EFT have compared this to viewing a Pointillist painting: set the order of magnitude we view the universe at and we see it clearly — not too close for its small-scale chaos, nor too far for relativistic warping.
This has given physicists a powerful new tool with which to view the cosmos, enabling them to make testable predictions about its very earliest beginnings.
“These new ideas can generate new science cases for future galaxy surveys,” Marko Simonović told Live Science. “As the new data start arriving in the coming years, it will certainly be very exciting to see what we can learn about our universe beyond what we already know and what surprises are waiting for us along the way.”
