Glossary

Let’s untangle quantum

As you explore our exhibition, you’ll encounter many quantum words. Here’s a guide to navigating them:

Black hole A region of spacetime whose gravitational pull is so strong that even light cannot escape once it crosses the event horizon. In fact, anything that crosses the event horizon is doomed to fall inward toward the singularity, where all matter and energy become compressed to a point of infinite density.

Classical physics Deterministic; unlike quantum physics. It assumes that if we know the initial conditions of a system, we can predict its future behavior with certainty.

Cosmic Microwave Background (CMB) Light from the early universe, emitted 380,000 years after the Big Bang, and a snapshot of the oldest light in our universe. It is conclusive evidence for the Big Bang theory. The 'temperature' of deep space has been measured as around 3K, not absolute zero, due to the afterglow of the Big Bang. This radiation is now used to 'map' the early Universe.

General relativity Improves on special relativity by incorporating acceleration and, as a natural consequence, gravity. The theory is often summarised with the following quote (attributed to John Wheeler): "Matter tells spacetime how to curve; spacetime tells matter how to move". It is precisely the motion of matter through a curved spacetime that we experience as gravity.

Gravitational Waves "Ripples" or distortions in the fabric of space-time that travel across the universe at the speed of light.

Heisenberg's Uncertainty Principle States that you can't measure all the properties of a quantum system with absolute certainty. For example, if you're very certain about the speed of a quantum particle, you'll be very uncertain about its location!

Parallel universe (bubble universe) This multiverse theory proposes that the universe is expanding at different rates in different regions. If this happens, bubbles of spacetime containing different universes can form in regions where the expansion is slower, but the rapid expansion between the separate universes prevents us from being able to communicate with them.

Parallel universe (Many Worlds Interpretation) Proposes that every quantum event with multiple possible outcomes results in a "split" or branching of the universe, with each outcome occurring in a separate, parallel reality. This interpretation provides a way to understand quantum phenomena without requiring a "wave function collapse" when a measurement is made; instead of the quantum state collapsing, a parallel reality is created.

Quantum Entanglement A phenomenon where two or more quantum particles become linked, such that their individual quantum states cannot be described independently, even when separated by vast distances.

Quantum fluctuations A consequence of Heisenberg's uncertainty principle, and can be thought of as temporary, random changes in energy (or virtual particles) that occur everywhere in space.

Quantum mechanics Describes the behavior of matter and energy at the atomic and subatomic levels.

Qubit The fundamental unit of information in quantum computing, like the ‘bit’ in a classical computer; the basic building block for all data and processing within the system.

Spacetime A four-dimensional framework that merges three dimensions of space with the one dimension of time, as described by Albert Einstein's theory of special relativity.

Special Relativity Albert Einstein's theory describing how space and time are intertwined (see Spacetime) and change for observers depending on their motion, but only for objects which are not accelerating.

Superposition The quantum mechanical principle that allows a particle to exist in multiple states, such as multiple locations or energy levels, simultaneously, until the particle is observed or measured. When the measurement happens, a ‘wave function collapse’ happens and the particle returns to a single definite location.