Vast digital archives from particle accelerators like the Large Hadron Collider hold the potential for future scientific breakthroughs, prompting a global effort to preserve this unique and irreplaceable data for generations of physicists to come. The enormous datasets, products of billions of dollars in public investment, contain far more scientific information than can be analyzed with today’s technology and theoretical models. As computing capabilities and our understanding of physics evolve, these meticulously saved records of subatomic collisions could be re-examined to reveal new particles or phenomena that were previously undetectable.
Ensuring this data remains accessible and usable is a monumental challenge that extends beyond simple storage. The task requires maintaining the complex software environments needed to interpret the raw information, preserving decades-old documentation, and retaining the human expertise required to navigate these intricate systems. International collaborations are now establishing new policies and best practices to safeguard this digital legacy, recognizing that the cost of preservation is a small fraction of the potential scientific return and a fundamental obligation to maximize the value of these historic experiments.
The Scale of a Digital Universe
Modern particle physics experiments generate data on a scale that is difficult to comprehend. At the Large Hadron Collider (LHC) at CERN, for example, about a billion particle collisions occur every second inside its massive detectors. This furious activity produces approximately one petabyte of data per second, a torrent of information that is impossible to store in its entirety. To manage this, highly selective automated systems called trigger systems discard more than 99.999% of the incoming data in real-time, identifying and saving only the collisions deemed most scientifically interesting.
Even after this aggressive filtering, the volume of data that reaches CERN’s long-term tape storage is staggering, constituting the largest scientific dataset ever collected. This archive grows by over 100 petabytes annually, a treasure trove for physicists. The scientific value of such datasets has been proven by past experiments. Data from the Large Electron–Positron Collider (LEP), which stopped running in 2000, and the HERA collider in Germany are still being analyzed today, yielding fresh insights into the strong interaction and informing the design of future colliders nearly two decades after their shutdown. This history underscores the core motivation for preservation: the full scientific potential of a collider’s data is realized over decades, long after the machine itself has been decommissioned.
Challenges Beyond Mere Storage
Preserving particle physics data is not as simple as saving files to a hard drive. The primary challenge is ensuring the long-term usability of the data. This requires a multi-faceted approach to combat the decay of both technology and human knowledge. The data itself, without the complex software used to analyze it, is largely meaningless.
Software and Knowledge Obsolescence
Much of the critical software needed to interpret data from older experiments was written in legacy programming languages like Fortran 77. To remain functional, this software must be continuously ported to modern operating systems and 64-bit architectures, a task that requires specialized expertise. This knowledge is often held by the original scientists and programmers who developed the systems. As these experts retire or leave the field, their invaluable understanding of the software’s intricacies is at risk of being lost forever. Furthermore, essential context is often buried in documentation, websites, and even old email threads, all of which present their own preservation hurdles.
Technological Migration
The physical media on which data is stored also evolves. Data must be migrated to new technologies every few years to prevent it from becoming unreadable as old hardware becomes obsolete. While preserving the raw bits of data is relatively straightforward, ensuring that discovery and access protocols keep pace with changing standards is a continuous effort. A dataset preserved for two decades may need to be migrated multiple times and have its access methods completely overhauled to remain viable for future researchers.
A Global Commitment to Open Science
Recognizing these challenges, the high-energy physics community has organized a coordinated international response. The Data Preservation in High-Energy Physics (DPHEP) group, established under the International Committee for Future Accelerators (ICFA), is at the forefront of this effort. This collaboration develops best-practice recommendations and policy guidelines to standardize preservation efforts across different experiments and institutions, ensuring a unified approach to safeguarding the world’s physics data.
A central pillar of this movement is the principle of open science. Many scientists and funding agencies argue that since the research is publicly funded, its outputs—including the data—should be publicly accessible. This philosophy not only fulfills a moral obligation but also enhances scientific discovery by allowing researchers outside the original collaborations to conduct novel analyses. CERN has embraced this by creating the CERN Open Data Portal, which hosts petabytes of data, along with the preserved software, analysis examples, and documentation necessary to use it. Experiments like CMS have committed to releasing 100% of their data within a ten-year window, guaranteeing that external researchers can look for discoveries the original team may have missed.
Investing in Future Discovery
The effort to preserve collider data is ultimately an investment in the future of physics. New theories may emerge years from now that predict subtle signatures hidden within existing datasets. Advanced analysis techniques, perhaps driven by machine learning and artificial intelligence, could unlock discoveries that are currently impossible to extract. The High-Luminosity LHC, the next major upgrade to the collider, will produce data streams even more massive than today’s, making robust preservation strategies more critical than ever.
Proponents estimate that dedicating less than 1% of a facility’s construction budget to data preservation could increase its total scientific output by more than 10%. This small upfront investment ensures that the immense value of these unique, multi-billion-dollar experiments is maximized over the long term. By carefully archiving not just the data but also the tools and knowledge required to interpret it, physicists are providing a foundation for the next generation to build upon, ensuring that the legacy of today’s colliders will continue to fuel discovery for decades to come.
