Will the Universe reveal a big secret? Deep underground in the Alps, scientists are barely able to contain their excitement about the world's most advanced particle accelerator.
The machine that could revolutionise physics
Will the Universe reveal a big secret? Deep underground in the Alps, scientists are barely able to contain their excitement about the world's most advanced particle accelerator.
"It's a really exciting time," says Dr Marcella Bona. "We are ready."
She is 100 metres below the French-Swiss border inside the biggest scientific instrument ever built. The Large Hadron Collider (LHC) fires photons around a 27km tunnel close to the speed of light. Scientists smash these particles together to unlock the secrets of the Universe.
After a three-year shutdown for a major upgrade, the LHC is back on. The revamped particle accelerator has narrower beams and more sensitive detectors. It allows physicists to analyse more collisions in greater detail.
They hope it will start a scientific revolution.
Quantum physics studies the behaviour and properties of atoms and subatomic particles. For five decades, the Standard Model has explained how particles interact via three forces of nature. These are electromagnetismThe force that holds atoms and molecules together, without which matter could not exist., the weak forceThe force that causes radioactive substances to decay. Without it, stars could not exist. that causes radioactivity and the strong forceThe force that holds together protons and neutrons in the nucleus of every atom. that binds atoms together.
But the model does not explain gravity, the fourth force. And it cannot make sense of the mysterious dark matterA hypothetical substance that can not be detected by scientific instruments. Its existence is inferred from evidence that the universe consists of more mass than we can perceive. that makes up over 80% of the Universe. Or the dark energyAn unknown form of energy causing the expansion of the universe to accelerate. that causes it to keep expanding.
When the LHC begins breaking apart protons, physicists hope to discover particles unknown to science. Evidence of a fifth force of nature could lead to a "theory of everything" that can explain all the mysteries of the Universe.
Expectations are growing. Last year, a US collider reported unexpected results that don't fit the Standard Model. The LHC has already measured strange behaviour in decaying quarksExperiments suggest some unseen particle or force is affecting how these elementary particles break down in the particle accelerator.. Both hint at a blockbuster breakthrough on the horizon.
Dr Sam Harper is a "little bit terrified". His 20-year hunt for a fifth force may be about to end. "There could be a revolution coming," says physicist Mitesh Patel. "Fingers crossed."
However, one or two results are not scientific proof. Researchers must reproduce these experiments thousands of times and rule out machine and human error. Ten years after the LHC discovered the Higgs bosonThe subatomic particle was first theorised in the 1960s, but observed in the LHC in 2012. Its existence does not challenge the Standard Model of particle physics. particle, the world is still waiting for the long-predicted scientific revolution.
"Let's be honest: It's disappointing," says physicist Sabine Hossenfelder. She argues that scientific predictions are "guesswork" and a huge amount of public money is being wasted on a hunch.
Could it also be dangerous? When the LHC was switched on in 2008, headlines warned of black holes that would grow and devour the Earth. This did not happen. And physicists are confident it is impossible.
CERN says the unlikely creation of "quantum black holes" at the LHC would be "thrilling", helping us understand how gravity works. But they would pose no threat to humanity and vanish almost instantly, according to the calculations of Stephen HawkingOne of the most revered modern physicists, he is best known for his book A Brief History of Time..
The stakes are sky high as Dr Harper waits for the first results of the supercharged LHC. "This would upend the field. It would be the biggest discovery in particle physics since, since..."
He is at a loss for words. The excitement is palpable.
Will the Universe reveal a big secret?
Yes: Science is on the brink of something big. These giant colliders are throwing out results that current theories can't explain. The next few years will be a momentous time for the field of physics.
No: This is the end of physics. We have reached the limit of what science can tell us about the universe. Physicists offer theories of parallel universes and fifth forces, but can't provide any proof.
Or... The Universe may reveal its secrets when we least expect it. Physicists are confident they are on the right path, but many discoveries have been accidental, like X-rays, microwaves and radioactivity.
Keywords
Electromagnetism - The force that holds atoms and molecules together, without which matter could not exist.
Weak force - The force that causes radioactive substances to decay. Without it, stars could not exist.
Strong force - The force that holds together protons and neutrons in the nucleus of every atom.
Dark matter - A hypothetical substance that can not be detected by scientific instruments. Its existence is inferred from evidence that the universe consists of more mass than we can perceive.
Dark energy - An unknown form of energy causing the expansion of the universe to accelerate.
Quarks - Experiments suggest some unseen particle or force is affecting how these elementary particles break down in the particle accelerator.
Higgs boson - The subatomic particle was first theorised in the 1960s, but observed in the LHC in 2012. Its existence does not challenge the Standard Model of particle physics.
Stephen Hawking - One of the most revered modern physicists, he is best known for his book A Brief History of Time.
The machine that could revolutionise physics
Glossary
Electromagnetism - The force that holds atoms and molecules together, without which matter could not exist.
Weak force - The force that causes radioactive substances to decay. Without it, stars could not exist.
Strong force - The force that holds together protons and neutrons in the nucleus of every atom.
Dark matter - A hypothetical substance that can not be detected by scientific instruments. Its existence is inferred from evidence that the universe consists of more mass than we can perceive.
Dark energy - An unknown form of energy causing the expansion of the universe to accelerate.
Quarks - Experiments suggest some unseen particle or force is affecting how these elementary particles break down in the particle accelerator.
Higgs boson - The subatomic particle was first theorised in the 1960s, but observed in the LHC in 2012. Its existence does not challenge the Standard Model of particle physics.
Stephen Hawking - One of the most revered modern physicists, he is best known for his book A Brief History of Time.