What will the revamped Large Hadron Collider tell us about the universe?

The Hadron Collider's job will be to smash subatomic particles together at almost the speed of light, ITV News' Callum Watkinson reports

The world's largest and most powerful particle collider is being rebooted on Friday after an extensive upgrade that is hoped will open the way to new frontiers in physics.

The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (Cern) in Switzerland is to be restarted after a more than three-year shutdown for maintenance, consolidation and upgrade work.

Once it is fired up (which could take up to eight weeks) it will operate at an even higher energy allowing it to find the smallest particles in the universe and, it is hoped, reveal knowledge about the fundamental laws of the universe.

The LHC, the machine that found the Higgs boson particle, is expected to be running at full power by the start of this summer, and collecting data from collisions not only at a record energy, but also in unparalleled numbers.

Just how powerful is the revamped LHC and what do scientists hope it will discover?

What is the LHC?

The LHC is the world’s largest and most powerful particle collider – it accelerates subatomic particles to almost the speed of light, before smashing them into each other.

These collisions produce a burst of new particles, which physicists record and study in order to better understand the basic building blocks of nature.

Scientists hope the upgrade will help them discover previously unknown particles or physical properties.

The atom smasher has played an important role in making physics discoveries. It most famously discovered experimental evidence for the Higgs boson particle in 2012, which, along with its linked energy field, is thought to be vital to the formation of the universe after the Big Bang 13.7 billion years ago.

Why was the LHC rebooted?

The 27-km Large Hadron Collider was shut down at the start of 2019 for maintenance and upgrades, which was delayed due to the pandemic.

Restarting the LHC is a complex procedure and it will take weeks to get up to full speed. LHC experts will work around the clock to progressively recommission the machine and safely ramp up the energy and intensity of the beams.

"It's not flipping a button," Rende Steerenberg, in charge of control room operations, told Reuters. "This comes with a certain sense of tension, nervousness."

How powerful is the revamped LHC?

The upgrade means the LHC will deliver collisions to the experiments at a record energy of 13.6 trillion electronvolts (13.6 TeV).

“The machines and facilities underwent major upgrades during the second long shutdown of CERN’s accelerator complex,” said CERN’s Director for Accelerators and Technology, Mike Lamont.

“The LHC itself has undergone an extensive consolidation programme and will now operate at an even higher energy and, thanks to major improvements in the injector complex, it will deliver significantly more data to the upgraded LHC experiments.”

What do scientists hope to discover?

Scientists do not know what 95% of the universe is made of and it is hoped the LHC will provide some answers.

One mystery that cannot be explained by the current laws of nature was discovered during the LHC's shutdown.

The LHCb Collaboration at Cern found particles not behaving in the way they should according to the guiding theory of particle physics – the Standard Model.

The model predicts that particles called beauty quarks, which are measured in the LHCb experiment, should decay into either muons or electrons in equal measure.

However, findings from March 2021 suggest this may not be happening, which could point to the existence of new particles or interactions not explained by the Standard Model.

The Standard Model describes all the known fundamental particles that make up our universe and the forces that they interact with. However, it cannot explain some of the deepest mysteries in modern physics, including what dark matter is made of and the imbalance of matter and antimatter in the universe.

To help solve some of these mysteries, researchers have been searching for particles behaving in different ways than would be expected in the Standard Model.