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Postcards from the Terascale

The sun warms planet Earth, but we live in a universe where the temperature of space is only three degrees above absolute zero. Its energy is so low that we can no longer see what space contained in the inferno of its birth. As the universe cooled from the Big Bang, it passed through a series of phases, each at a lower energy and each with its own set of particles and forces acting according to its own physical laws.

Particle accelerators give us the opportunity to go back and revisit the higher energies of our ancestral universe, to observe phenomena no longer visible in our own era. These high-energy phenomena are important to us, because our universe today still feels their imprint. The order behind what appears arbitrary in our own universe becomes clear at higher energies.

For example, many theories predict that at the extreme energy just after the Big Bang, all of nature’s forces were combined in one single unified force, splitting as the universe cooled into the four forces that we know today. Reconnecting to the early universe may reveal how gravity relates to electromagnetism as different aspects of a single principle of nature.

Since the early cyclotrons of the 1950s, particle accelerators have served as the passports to higher and higher energies. The entire standard model of the structure of matter, with its fundamental particles and forces, has emerged from the increasing energies of particle collisions. Each generation of accelerators has built on the discoveries of previous generations to venture deeper into the history of the universe. Now, a new generation of accelerators with the highest energies yet will open up for exploration a region of energy – the Terascale – that has ten thousand trillion times the energy of space today. Postcards from the Terascale will answer basic questions about the universe.

Moreover, the Terascale is not the end of the story. Discoveries there may reveal phenomena occurring at energies so high that no particle accelerator will ever achieve them directly. Such postcards from the Planck scale once seemed an unreachable fantasy. Forwarded from an address in the Terascale, they may one day arrive.