Antony Hewish – Nominations
Martin Ryle – Nominations
Speed read: Radio stars
The 1974 Nobel Prize for Physics was awarded to Sir Martin Ryle and Antony Hewish for their pioneering efforts to tune in to radio broadcasts from the stars. Their development and use of radio-based versions of telescopes has broadened our view of the universe by revealing information about stars in remarkable detail.
Sir Martin Ryle applied his expertise in developing airborne radar systems during the Second World War to intercepting radio transmissions that stars send out as they burn their fuel. Constructing a series of telescopes consisting of radio antennae attached to large receiver dishes allowed Ryle to detect characteristics of the Sun, such as its surrounding layer of hot gas, called the corona. Recognising more faint and distant stars was a daunting task, thought to be possible only by building dishes of impossible proportions, but Ryle’s finest technical achievement was showing that this could also be achieved by connecting a series of small telescopes all pointing in the same direction, a set-up known as aperture synthesis.
One of the most remarkable observations using radio astronomy was made in 1968, when Antony Hewish’s graduate student, Jocelyn Bell, spotted something in the skies that didn’t twinkle like a normal star. Spinning around rapidly this star shoots out a powerful lighthouse-like beam of radio waves, and as the beam repeatedly sweeps around it appears to blink every second when viewed from Earth. Hewish’s suggestion, later proved true, was that this so-called pulsar was the first sighting of the dense, burnt-out remains of a massive star that had been predicted to exist as far back as the 1930s. As these stars die spectacularly in a supernova explosion the extreme conditions fuse almost all the components of their atoms together to form a crushed ball of neutrons, hence their name neutron stars.
Ryle and Hewish’s Prize in Physics was the first to celebrate breakthroughs in astronomy. Ryle also had the additional honour of being the 100th individual to be awarded the Physics Prize since the first, Wilhelm Röntgen, in 1901.
Antony Hewish – Other resources
Links to other sites
On Antony Hewish from American Institute of Physics
Obituary from Churchill College University of Cambridge
Martin Ryle – Nobel Lecture
Nobel Lecture, December 12, 1974
Radio Telescopes of Large Resolving Power
Read the Nobel Lecture
Pdf 1.26 MB
Antony Hewish – Nobel Lecture
Nobel Lecture, December 12, 1974
Pulsars and High Density Physics
Read the Nobel Lecture
Pdf 162 kB
Antony Hewish – Banquet speech
Antony Hewish’s speech at the Nobel Banquet, December 10, 1974
Your Majesty, Your Royal Highnesses, Ladies and Gentlemen,
The world of man lies midway in scale between the inner space of atoms and particles, and the outer space of stars and galaxies. The exploration of both these regions stretches our imagination to its limits.
In deciding to honour the field of Astrophysics the Nobel Foundation, and the Royal Academy of Sciences, have given great encouragement and delight to all astronomers who share with us this proud moment. Sir Martin Ryle and I know this well from the countless messages that we have received from all over the world.
There is, I think, some special benefit for mankind in the realm of astrophysics. It is impossible to witness the interplay of galaxies without a sense of wonder, and looking back at Earth we see it in its true perspective, a planet of great beauty, an undivided sphere. Let us try and keep this image always in our view.
Antony Hewish – Interview
Martin Ryle – Facts
Press release
15 October 1974
The Royal Swedish Academy of Sciences has awarded Professor Martin Ryle and Professor Antony Hewish the 1974 Nobel Prize in Physics. Professors Ryle and Hewish have been awarded the Prize for their pioneering research in radioastrophysics: Ryle for his observations and inventions, in particular of the aperture-synthesis technique, and Hewish for his decisive role in the discovery of pulsars.
THE PHYSICS OF THE STARS
Astrophysics, the science dealing with the physical properties of the stars and the stellar systems, has developed rapidly during recent decades. This is mainly due to new discoveries made with radio astronomical methods. These methods are of vital importance when making observations over cosmic distances, thousands of millions of lightyears or more. It is essential that such distances can be covered when trying to chart the development of the universe. A light year is the distance that light travels in one year. Light moves at a speed of 300 pillion metres per second.
In contrast to visible light coming to us from the celestial sphere, radio emission from other space can only be perceived with the help of telescopes. Highly sensitive electronic instruments amplify and handle the data-processing of the signals.
SEVERAL SMALL TELESCOPES “FORM” ONE LARGE TELESCOPE
During the last twenty-five years, Martin Ryle has developed new epochmaking telescope constructions and registration principles. With the help of these he has explored the radio sources of the universe and gradually achieved greater and greater accuracy in the determination of direction. Definition is now so good that in the case of visible light it corresponds to an observer on earth being able to see the details of a postage stamp on the moon, Ryle has developed a technique – the aperture synthesis technique – which means that with the help of a number of small telescopes, whose positions are mutually adjustable within a distance of nearly 5 kilometers he can achieve a precision equalling that obtainable by having the whole area covered by a single vast telescope, a construction which is technically not possible. Ryle also makes use here of the rotation of the earth to change telescopic positions in relation to the celestial sphere.
The wealth of detail in the charting of the universe carried out in recent years with this apparatus is absolutely unique. For a number of years Ryle has been making observations with his various instruments that have been of crucial significance in the study of the physical characteristics of stars and stellar systems and for cosmology, the study of the development of the universe as a whole.
THE PULSARS
In the summer of 1967 Antony Hewish started a series of observations which soon led to an extremely interesting and quite unforeseen discovery. Some radio sources in space, later given the name “pulsars”, emitted radio signals – pulses – which were repeated extremely regularly at intervals of a second or so. As a result of this discovery it has been possible to establish the presence of so-called neutron stars in the universe, something that scientists have been speculating about ever since the Thirties. Neutron stars are bodies which are extremely heavy, in comparison to their size – about 10 kilometres in diameter. One cubic centimetre of neutron-star matter of which the pulsars consist, weighs millions of tons! The observed emission from a pulsar shows that they must have a magnetic field which is extraordinarily strong many millions of times stronger than any magnetic field used in the laboratories on earth. Every signal from the pulsars corresponds to enormous quantities of energy. It is probable that the neutron star, which is the “nucleus” of a pulsar, surrounds itself with a plasma, a gas conducting electricity, and the whole system including the magnetic field rotates. The pulsar is then perceived from the earth as a radio beacon!
The best known pulsar is to be found in the Crab Nebula. This nebula consists of a glowing cloud of gas, the remains of a stellar explosion, which according to Chinese records took place in 1054 A.D. It is one of the most interesting phenomena in the heavens. It has been found that its centre, from which it expands, contains a pulsar emitting not only radio pulses but also light pulses and X-ray pulses.
The discovery of the pulsars is of paramount importance to physics and astrophysics. The pulsars play a vital role in the genesis of the elements and the chemical development of the galaxies. New avenues have been opened up for studying the properties of matter under very extreme conditions.