The origin of quasars – Malcolm Longair 1990 Christmas Lectures 3/5
In his third lecture Malcolm Longair explains how quasars were discovered.Watch all the lectures in this series here: https://www.youtube.com/playlist?list=PLbnrZHfNEDZy_oby1AwnVub0zqFr0Xfn2
Watch our newest Christmas lectures here: https://www.youtube.com/playlist?list=PLbnrZHfNEDZyQJZLPMjwEoOLdkFBLU2m1
This was recorded on 3 Dec 1990.
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This year marks 200 years of the Royal Institution Christmas Lectures — a world famous series showcasing science, curiosity, and mind-blowing demos, and started by the legendary Michael Faraday himself. To celebrate, we're unlocking the archive. We're uploading all the classic lectures to our YouTube channel — some not seen since they aired on TV. Sign up as a Science Supporter and get early access here: https://www.youtube.com/channel/UCYeF244yNGuFefuFKqxIAXw/join
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From the 1990 programme notes:
Up till about 1950, astronomers believed that the galaxies consisted of stars and gas, but with the development of radio astronomy, it became apparent that galaxies also contain magnetic fields and very high energy particles. What came as a complete surprise was the fact that there are some galaxies which are quite extraordinarily powerful sources of radio emission. Some of these must generate huge fluxes of very high energy particles which are ejected far beyond the confines of the galaxy. But even bigger surprises were in store. Radio astronomical observations led to the discovery of the quasars - these are the nuclei of galaxies which can have luminosities over 1000 times greater than the total light of the galaxy and which must originate within a very small volume in the nucleus. How can we explain these remarkable phenomena?
Crucial clues come from other remarkable discoveries of the 1960s and 1970s. In 1967, the pulsars were discovered and these turned out to be neutron starts, the last stable form of star. X-ray pulsating sources similar to pulsars were discovered in the early 1970s and they provided the crucial clue that accretion of matter on to compact objects is a very powerful source of energy.
The most compact objects are the black holes - in these objects, no physical force can prevent matter falling inwards under the influence of gravity. We will study their remarkable properties and show how they are potentially the most powerful sources of energy we have in the Universe. We can show in principle how we can generate the enormous luminosities of quasars and explain the short time-scales over which they vary.
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About the 1990 CHRISTMAS LECTURES
The astronomical sciences have developed out of all recognition over the last 40 years. Up till about 1950, astronomy meant optical astronomy, but now it could mean radio astronomy, X-ray astronomy, infrared and ultraviolet astronomy, γ-ray astronomy and even more exotic ways of looking at the Universe through neutrino astronomy. Each of these disciplines has contributed essential new facts about the origin and evolution of different classes of object in the Universe. The aim of these lectures is to put all this new knowledge into a coherent picture of our present understanding of the origin and evolution of the Universe.
To solve the problems of the origins of astronomical systems, we must call upon an enormous range of physical tools to understand what it is we have to explain. We need to introduce many ideas from simple physics in order to define precisely the astrophysical problems which have to be solved. We will introduce these ideas as the lectures develop – we will need ideas like Newton’s law of gravity, the conservation of angular momentum, Einstein’s mass-energy relation E = mc2, simple ideas about black holes, nuclear reactions in stars and so on. We will introduce much of the essential physics through demonstrations, models and analogies. By the end of the lectures, we will not have answered the question of the origins of all the contents of the Universe but we will have gained an understanding of what the key questions are which still need to be addressed.
Find out more about the CHRISTMAS LECTURES here: https://www.rigb.org/christmas-lectures
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