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Maarten Schmidt, the father of quasars, dies at age 92




The astronomer mourned the death of Dutch-American astronomer Martin Schmidt, the first person to measure the distance to the quasar. His pioneering work in the 1960s greatly expanded the size of the known universe, providing one of the first clues to the validity of the Big Bang theory. Schmidt died on September 17 at his home in Fresno, California. He was 92 years old.

The story about the quasars began several years before Schmidt turned his attention to it. Beginning in the 1950s, astronomers identified several sources of radio emissions in the sky. Many of these radio sources can be assigned to known objects, such as bright stars or nearby galaxies. But some have remained frustratingly elusive, with no visible counterpart. Whatever these strange radio sources were, they appeared as dot-like objects, indicating that they were either huge in size but incredibly far away or small and close.

Never slow to assign a name to a new class of celestial phenomena, astronomers quickly identified these radio sources as “quasars,” shortened to quasars.

Quasar Mysteries Revealed

Schmidt, who received his Doctor of Philosophy degree from Leiden University in 1956 under the tutelage of Dutch astronomer Jan Oort (of Oort-Cloud fame), eventually moved to Caltech to continue his studies in the properties and evolution of galaxies. Among Schmidt’s many accomplishments during his time there, he was the first to discover that the density of interstellar gas within galaxies was proportional to the rate of star formation, a relationship now known as Schmidt’s Law (or more recently, Kennicott-Schmidt’s Law). Law).

Schmidt then turned his attention to finding the light spectra of radio sources, especially these mysterious quasars. By the early 1960s, astronomers were able to determine isotopes of optical light for another quasar, but its spectrum remained poorly understood—the light output did not match that of any other known type of astronomical object.

In 1963, Schmidt used the 200-inch Hill Telescope at Palomar Observatory to discover the optical analogue of the quasar known as 3C 273, one of the first telescopes to be discovered. He also collected the spectrum of this poorly understood object, and this spectrum was characterized by strange emission lines, which, again, defy interpretation.

After several weeks of deep meditation and much nervousness around his home, Schmidt realized what he was looking at: a perfectly normal galaxy. All the emission lines from all the usual elements were present, such as hydrogen and helium, but they were simply shifted away towards the red end of the spectrum.

The spectrum of light can be transmitted to an astronomical object from two things. The first is the Doppler effect: if an object is moving away from us, the wavelength of its emitted light will lengthen, and its emission lines will turn red. But the location of the emission lines from 3C 273 indicates a sluggish speed of about 100 million miles per hour, about 15 percent of the speed of light!

This redshift result was greater than that found for any other known object.

Quasars: the luminous cores of distant galaxies

Schmidt argued in another interpretation of it temper nature A paper describing his discovery: The Big Bang. Objects further away from us are drawn in due to the expansion of the space itself, which also leads to redshift. It was this realization that allowed Edwin Hubble to lay the observational basis for the Big Bang theory in the 1920s. But besides Hubble’s vision, there wasn’t much to solidify the explosion in the observations. Thus astronomers continued to debate its validity.

Schmidt’s work showed that 3C 273 was billions of light years away, making it the farthest known astronomical object at the time. This discovery of the first distance to the quasar rewrote our understanding of the true scale of the universe.

For quasars to be detectable at such vast distances, they must be insanely luminous. In fact, they must be the most luminous thing in the universe. Schmidt thought that when we observe a quasar, we see the light emitted as the gas spins violently and grinds together around a giant black hole in a newly formed galaxy, which is the correct explanation.

The presence of quasars provided Big Bang supporters a huge observational win. Quasars appear only in the distant universe. There are no things close like them.

In the Big Bang model, the universe changes and evolves as it continues to cool and expand. Because quasars are only found in very distant places, they must have only existed in the early universe, not the modern universe.


In 1966, time The magazine put Schmidt on its cover, likening his discovery of the true nature of quasars to Galileo’s in its ability to reshape our understanding of the universe. Such an achievement is sure to continue.


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