top of page

New particle collider? New space telescope? This principle helps scientists decide

Writer's picture: Ethan SiegelEthan Siegel

“Discovery potential” – the difference in capabilities between today’s best scientific tools and what current (or projected) technology could enable – helps scientists decide what to build next.


View of the Large Hadron Collider tunnel at CERN.
The Large Hadron Collider (Credit: CERN)

In the world of particle physics, the Large Hadron Collider (LHC) at CERN is by far the most powerful machine ever built. It revealed the Higgs boson and allowed us to begin studying its properties. It has produced conditions that generate enormous numbers of top quarks – the heaviest, shortest-lived particle of all – and even provided indirect evidence of quantum entanglement between top-antitop pairs of particles. And it’s allowed us to study particle decays in greater detail than ever.


Meanwhile, in space, observatories like Fermi (in gamma-rays), Chandra (in X-rays), Hubble (in optical light), and JWST (in infrared light) continue to illuminate new details about the universe, finding ultra-distant, ultra-faint, and ultra-rare objects of all varieties – from planetary systems to galaxies, galaxy clusters, and much more.


And yet, it seems as though scientists are never satisfied. Every one of the enormous scientific apparatuses we’ve built – particle colliders, space-based observatories, ground-based telescopes, gravitational wave detectors, etc. – are still fundamentally limited, leaving the possibility open that a new, more powerful instrument could make discoveries that are beyond the reach of our current scientific tools.


Almost all scientists who probe the essential workings of the universe, whether on cosmic or subatomic scales, are well aware of our existing limitations, and strive to go beyond them – learning the truth behind current speculation.


But how do we decide what to build and when to build it? What determines whether it’s worth it, and what our highest priorities should be? The answer comes down to a simple term that most people outside of these scientific fields have never heard of: discovery potential.


What is “discovery potential”?

Discovery potential is simply a comparative way of looking at two things side-by-side: What are the capabilities of today’s best scientific tools, as they exist right now, for probing a specific aspect of the universe? And what capabilities would a new scientific tool, built with current (or projected near-future) technology, possess for probing those very same aspects?


When there’s little difference between these two options, then the discovery potential is low and it is not yet worth building a new, next-generation tool for probing the universe.


However, when the difference is large, that means three separate things:


  1. Scientifically, we’ll be able to do everything we’ve already done but better: collide and create more particles, find and image more objects in greater detail, or discover predicted objects and phenomena that cannot be accessed by the current generations of scientific tools.

  2. Technologically, these novel capabilities will also grant scientists the ability to find “surprises,” which includes objects or phenomena that weren’t necessarily expected, but whose existence can be revealed or constrained by these new tools.

  3. And practically, if the price is right – i.e., if the project can acquire sufficient funding to reach the desired technical goals – it’s time to act: to bring these new tools to fruition.


For particle accelerators, those frontiers include the ability to create large numbers of the heaviest known particles and study their decays, to collide greater numbers of particles together, and to collide particles at unprecedented energies. For space telescopes, those frontiers include superior resolution, increased light-gathering power, and wider fields-of-view across every relevant wavelength range.


It’s worth noting, of course, that factors beyond scientific considerations (geopolitical, economic, etc.) can also influence the prioritization of large-scale projects, particularly when international collaboration is required.


Based on discovery potential, what should we build next?


Comparison of size and energy levels of the proposed Future Circular Collider with current and previous colliders.
Comparison of size and energy levels of the proposed Future Circular Collider with current and previous colliders (Credit: Wikimedia)

The differences between the prior generation of the world’s most powerful particle accelerator-colliders (Fermilab’s Tevatron and CERN’s LEP2) and the current generation (CERN’s LHC) are a factor of ~10 in energy and ~100 in particle collision rates. The difference between the prior generation of infrared space telescopes (WISE and Spitzer) versus the current generation (JWST) is a factor of ~10 in resolution and ~100 in light-gathering power.


So, in terms of particle colliders and space telescopes today, where can the greatest discovery potential be found?


A schematic map showing a possible location for the Future Circular Collider.
A schematic map showing a possible location for the Future Circular Collider (Credit: CERN)

For particle physics, the greatest scientific gains would come from building a new, larger-than-ever circular collider: with an 80+ km circumference and bending electromagnets that are at least double the strength of the LHC’s current magnets. A less expensive option with lower (but still significant) discovery potential would be a linear electron-positron collider – such as the proposed International Linear Collider (ILC) – capable of precision studies of W, Z, and Higgs bosons, as well as top-antitop quarks.


Meanwhile, over on the space telescope side, the wavelength ranges with the greatest opportunities for technological advancement are the far-infrared, where the ESA’s now-defunct Herschel mission set the prior standard; the X-ray, where NASA’s 25-year-old Chandra X-ray observatory is still the world’s most powerful; and the optical, where the 35-year-old Hubble Space Telescope still has yet to be surpassed.


No matter how much of the universe we explore, the tools we use to conduct that exploration will always have fundamental limitations. It’s the ability to push past the limits and into the frontier of the great unknown that enables science to advance.


The question shouldn’t ever be, “Is it worth it to continue to invest in fundamental science?” The relevant question is, “When should we do it?” And the answer can be found by looking at the discovery potential that a new machine would deliver.


A theoretical astrophysicist by training, Ethan Siegel took the unconventional path of ditching research to become a full-time science communicator. He is the creator of the science site Starts With a Bang and author of Infinite Cosmos: Visions from the James Webb Space Telescope, published by National Geographic.

iStock-1357123095.jpg
iStock-1357123095.jpg

Subscribe to our newsletter

Join the Community of Curious Minds

Stay Connected - Get our latest news and updates

  • LinkedIn
  • Youtube
  • X
  • Facebook

Stay Connected

facebook icon.png
X icon.png
linkedin icon.png
bottom of page