Quantum entanglement, termed 'spooky action at a distance' by Einstein, means:

Explanation

Quantum entanglement is the quantum-theory idea that particles which once shared an origin can remain connected even after they separate across space and time. NASA describes this as particles shedding their original quantum states and taking on a new united quantum state; if something happens to one, it affects the others with which it is entangled. That is why Einstein called it "spooky action at a distance": measuring one entangled particle can reveal the state of its partner far away. The key exam trap is that this does not mean usable faster-than-light communication. The concept matters because quantum entanglement underlies technologies such as quantum cryptography, quantum teleportation and quantum computing.

Why the other options are wrong

• (A) Physical contact is not the defining feature, because entangled particles can separate and still remain correlated across distance.
• (B) Entanglement is about a shared quantum state, not the destruction of particles.
• (C) The phenomenon creates an instant correlation in measurement outcomes, but it does not allow faster-than-light communication.

Concept

This tests the Science and Technology syllabus theme of quantum technologies and basic modern physics. It recurs in RAS because quantum entanglement links a core physics idea with applied areas such as cryptography, teleportation and computing.

Source

• NASA Science

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