Martin Ryle

Martin Ryle (1918–1984) was a British radio astronomer who developed aperture synthesis and shared the 1974 Nobel Prize in Physics for discoveries in radio astrophysics.

Radio astronomy: The study of celestial objects through the radio waves they emit or reflect. Ryle made radio observations a powerful way to investigate the universe.
Earth-rotation aperture synthesis: A technique that uses Earth’s rotation to sample different spatial frequencies with a radio interferometer. Ryle used rotation to expand the baseline coverage needed for radio images.
Third Cambridge Catalogue of Radio Sources: A 1959 catalogue of 471 radio sources compiled from the Cambridge radio survey. Ryle’s team produced this influential catalogue using a new interferometric survey.
Nobel Prize in Physics: An annual international award recognizing major contributions to physics. Ryle shared the 1974 prize for discoveries in radio astrophysics.
Radio source evolution: Changes over cosmic time in the abundance, luminosity, or properties of astronomical radio sources. Ryle’s source counts provided evidence that radio sources were more numerous in the past.
Radio interferometry: A technique that combines signals from separate radio antennas to improve angular resolution. Interferometry supplied the measurement principle behind Ryle’s telescope designs.
Radio telescope array: A group of radio antennas operated together as a single observing instrument. Arrays let Ryle combine separated antennas instead of building one enormous dish.
Fourth Cambridge Catalogue of Radio Sources: A 1962 catalogue of radio sources detected in a Cambridge survey at 178 megahertz. Its source counts supported Ryle’s argument that the radio-source population changed over cosmic time.
Antony Hewish: A British radio astronomer who shared the 1974 Nobel Prize in Physics with Ryle. Hewish led the Cambridge group that discovered pulsars using a radio telescope array.
Steady-state theory: A cosmological model in which the expanding universe maintains constant average density through continuous matter creation. Ryle’s source-count results challenged the theory’s claim of an unchanging universe.

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