Los Alamos National Labs with logo 2021

The computing issue

Los Alamos National Laboratory has led the world in developing and using computer simulations to understand the world around us.
December 1, 2020
A computer simulation of turbulence

Using a computational fluid dynamics code, a supercomputer can produce a model that simulates turbulence when materials (such as gases, liquids, or metals) mix and change states. For example, when the cold water of Antarctica mixes with the warm Gulf Stream, the interaction produces turbulence, which is seen as vortices and curves and offers valuable information about material interactions.CREDIT: Los Alamos National Laboratory


“Since the 1940s, scientists have increasingly relied on computer simulations to understand phenomena that cannot be experienced directly.”- John Scott

By John Scott, director, Office of National Security and International Studies

The world is made up of many physical systems—from natural systems, such as the formation of galaxies, to manmade systems, such as the detonation of a nuclear weapon. The experiments scientists conduct to understand physical systems provide us with knowledge essential for protecting the national interest, preventing disasters, finding cures for disease, and creating innovative, new technologies.

But what do scientists do when a physical system is too small, too large, too fast, too costly, too dangerous, or otherwise inaccessible for an experiment in a laboratory? Since the 1940s, scientists have increasingly relied on computer simulations to understand phenomena that cannot be experienced directly.

Computer simulations let scientists conduct virtual experiments using mathematical models—programs that attempt to replicate the natural behavior of an object or force. Virtual experiments open up new realms of research; for example, scientists can see a solar system evolve over eons. Virtual experiments also help us plan for complex situations, such as the need to avert an Earth-asteroid collision.

At Los Alamos, computing has been integral to our work since the Manhattan Project. In the early days, human computers—often the wives of scientists—performed calculations to support the development of the world’s first atomic bombs. Over time, human computers were phased out and replaced with mechanical and then electronic computers, such as the MANIAC. Today, we use supercomputers that perform billions of calculations per second.

In the Laboratory’s Weapons programs, scientists use this computing power to simulate nuclear explosions. The extreme conditions leading up to a nuclear explosion cause solid materials to flow and display instabilities and turbulence characteristic of fluids. Understanding the complex processes of instability and turbulence allows us to simulate with better accuracy the performance of America’s nuclear deterrent.

The Laboratory’s supercomputers are leveraged for non-weapons work, too. As you’ll read here, our supercomputers are being used in the fight against COVID-19. We also use our supercomputers to better understand biology, climate, space, and just about any other area of study one can think of.

As we begin to say goodbye to Trinity (currently the world’s seventh-fastest supercomputer, which is approaching the end of its useful life) and make plans to install its successor, Crossroads, we will continue to lead the world in computing power and drive the computing industry to develop ever-faster and more powerful computers. With our nation’s best interests at heart, we will continue to use computers to help us simulate what we can only imagine.

A man.

John Scott