For nearly a decade, physicists around the world have lamented the aborted construction of what was to be the largest single scientific instrument in history: the Superconducting Super Collider (SSC).

The ambitious design for the SSC involved the construction of a gigantic circular particle accelerator and collider, measuring 54 miles in circumference and housed in a massive set of underground tunnels beneath a lab in Texas. The SSC’s staggering scale carried an equally staggering, multibillion-dollar price tag, which the U.S. Congress eventually refused to fund.

Since the SSC’s cancellation in 1993, trivia aficionados have wondered: What exactly is the largest single scientific instrument in the world?

Some have suggested that the High Frequency VLBI Array, a multicontinent network of radio telescopes coordinated by a series of atomic clocks and a specialized supercomputer, fits the bill as the world’s largest scientific instrument. However, the VLBI Array is actually a collection of previously independent radio telescopes, so it doesn’t qualify as a single instrument. (The same reason would also disqualify the Internet.)

In fact, the reigning titan of scientific instruments is a cousin to the SSC and is itself on the road to replacement by a successor that’s already under construction.


What’s the world’s largest single scientific instrument, which is a cousin to the aborted Superconducting Super Collider (SSC) and is itself on the road to replacement?

The now inoperative Large Electron-Positron Collider (LEP) at the CERN physics laboratory in Switzerland measures roughly 17 miles in circumference. It’s less than one-third the size of the proposed SSC, but it’s still vast enough to qualify as the largest single scientific instrument ever built. Indeed, the LEP is so massive that the underground tunnel housing the device actually extends beyond the borders of Switzerland and into France.

The LEP operated for more than a decade before it shut down on Nov. 2, 2000 to make way (in the same tunnel, no less) for its successor: the Large Hadron Collider (LHC), scheduled to go online in 2005.

However, scientists won’t completely dismantle the LEP; the LHC will use not only the LEP’s underground tunnel, but it will also incorporate the LEP’s particle sources and preaccelerators. But once it begins operation, the Large Hadron Collider will formally inherit the title of “largest single scientific instrument” on Earth.