An unexpected finding about how our universe formed is again raising the question: do we need new physics? The answer could fundamentally change what physics students are taught in classes around the world.

A study from SMU and three other universities, available on the arXiv preprint server, delved into the possibility of updating fundamental physics concepts.

SMU played a significant part in the analysis, using the university’s high-performance computing capabilities to explore different scenarios that could explain the findings.

“The data from what’s known as DESI, or Dark Energy Spectroscopic Instrument, combined with what we already had, is the most precise data we’ve seen so far, and it is hinting at something unlike what we would have expected,” explained one of the study’s co-authors Joel Meyers, an associate professor of physics at SMU. “Now, we need to get to the bottom of why that is.”

Working with Meyers on this analysis were theoretical physicists Nathaniel Craig at UC Santa Barbara and the Kavli Institute for Theoretical Physics, Daniel Green at UC San Diego and Surjeet Rajendran at Johns Hopkins University.

What DESI found…and why it was surprising

DESI is creating the largest, most accurate 3D map of our universe, providing a key measurement that enables cosmologists to calculate what they call the absolute mass scale of neutrinos.

This absolute mass scale was determined based on new measurements from the so-called baryonic acoustic oscillations from DESI, plus information physicists already had from the “afterglow” of the Big Bang—when the universe was created—known as the cosmic microwave background.

Throughout the evolution of the universe, the behavior of neutrinos impacted the growth of large-scale structures, such as clusters of galaxies across vast reaches of space that we see today. Neutrinos are one of the most abundant subatomic particles in the universe, but they’re as mysterious as they are ubiquitous. One reason physicists want to know the mass scale of neutrinos is that it can help them get a better understanding of how matter clustered as the universe evolved.

Cosmologists—those who study the origin and development of the universe—have long thought that massive neutrinos kept matter in the universe from clustering as much as it otherwise might have over 13.8 billion years of cosmic evolution.

“But rather than the expected suppression of matter clustering, the data instead favors enhanced matter clustering, meaning matter in the cosmos is more clumped than one would expect,” said Meyers, who specializes in theoretical cosmology, including the cosmic microwave background, the early universe and connections to high energy and particle physics.

“Explaining this enhancement may point toward some problem with the measurements, or it could require some new physics not included in the Standard Model of particle physics and cosmology.”

The Standard Model of particle physics—the one that students likely learned in physics class—has long been scientists’ best theory to explain how the basic building blocks of matter interact. This finding of neutrinos is the latest measurement, similar to what’s referred to as “the Hubble tension,” to hint that we might not know our universe as well as we think we do, Meyers said.

In their study, Meyers and his colleagues looked into scenarios where physicists might need to tweak the Standard Model, but not throw it out entirely. They also examined introducing new concepts of physics. And they also explored whether systematic errors of key measures could account for the surprising DESI finding.

It will likely take years to know which of the researchers’ theories is correct. But the study gives a blueprint for future research.

New research published Sept. 19 in Geophysical Research Letters shows that using data collected by deep ocean robots, called Deep Argo floats, combined with historical data from research vessels has increased confidence that parts of the global deep ocean are warming at a rate of .0036 to .0072°F (.002 to .004°C) each year.

“Ocean warming is the dominant element of global warming and a major driver of climate change,” said Greg Johnson, an oceanographer at NOAA’s Pacific Marine Environmental Lab and lead author of the study.

“This study confirms the previously reported deep ocean warming, and reduces the uncertainties about the global ocean heat uptake in waters below 1.2 miles (2,000 meters), a key area of the ocean for predicting sea level rise and extreme weather.”

The new research also provides more detailed information about the geographic patterns of the deep ocean warming, which can help scientists better understand changes in the global ocean conveyor belt called the global meridional overturning circulation, also key to predicting weather and climate changes.

The research shows that the deepest ocean waters off Antarctica are a hot spot for warming. These bottom waters carry the warming north, traveling along the ocean conveyor belt. Another hot spot of warming is in the deep ocean waters off Greenland, which no longer receive large amounts of sinking cold waters from the ocean surface due to increased atmospheric warming and freshening of those surface waters from ice melt.

More detailed information about deep ocean warming can help improve climate models used to prepare society for future changes in ocean and air temperatures that drive sea level increases, precipitation, tropical cyclone frequency and intensity, and their impacts on humans and the environment.

Johnson said that scientists first began seeing this deep ocean warming trend off Antarctica without the benefit of Deep Argo data some two decades ago. But the size of the warming trend was quite uncertain because of the sparse measurements available previously. The new data from Deep Argo have helped to reduce the uncertainty in the size of the trend by a factor of two.

NOAA’s partners in the Argo Program first launched Deep Argo floats that could measure ocean temperature, salinity and other data down to a depth of 3.7 miles (6,000 meters) in 2014 in the Southwest Pacific off New Zealand.

Since that time, arrays of Deep Argo floats to measure deep ocean changes have been expanded in the Southwest Pacific and added in the South Atlantic off Brazil and Argentina, the South Indian Ocean between Australia and Antarctica, and the North Atlantic between Florida and North Africa.

“Right now, Deep Argo consists of pilot arrays in key regions,” said Johnson. “If we can build a global array we’ll be able to quantify the warming rate over shorter periods of time to see how that rate is changing.

“We have hints that the rate is changing but we need to be able to tease that out better. Measuring evolving temperature salinity patterns in the deep ocean will also aid in predicting climate changes decades in advance.”

Deep Argo is part of the overall Argo program, which is supported by NOAA’s Global Ocean Monitoring and Observing Program. Since its inception in 1999, the Argo Program has revolutionized our ability to track changes in the ocean with a global array of autonomous profiling floats, providing nearly four times the ocean information as all other observing tools combined.