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William Herschel and the Discovery of Black Holes

Sir William Herschel (November 15, 1738- August 25, 1822) was a German-born astronomer and composer, perhaps best known for discovering Uranus, along with four of its twenty-seven moons. He also made a number of other astronomical advances, including the development of a high-powered reflector telescope and many discoveries dealing with nebulae and solar systems, helping to define modern science’s understanding of deep space. Herschel’s work on binary stars proved Isaac Newton’s laws of gravity applied in outer space, clearing the path for a more contemporary understanding of the black hole. His work is also quite relevant as a romantic scientist, due to the heightened interest in astronomy at that time.

Early Life & Astronomical Background

Sir William Herschel was born in Hanover (in present-day Germany) in 1738. Though Herschel and his siblings were raised to be musicians, then a prestigious and lucrative career, his father, Isaac Herschel, nurtured his talented son’s talents both in music and in academia. Herschel’s youngest sister Caroline, who would later become his lab assistant and move on to become an astronomer in her own right, kept extensive journals throughout her life provide a glimpse into childhood life for the six Herschel siblings. Eldest brother Jacob was an extremely gifted musician and was spoiled by his mother Anna, though vain and hot-tempered. William, a talented oboe and harpsichord player, was always interested in science; his father Isaac supported his hobby and was glad to see his scientific models. According to Caroline, the brothers Jacob and William used to debate science and philosophy, and William was always especially interested in the ideas of Isaac Newton, whose work would later influence some major findings of Herschel’s own. William Herschel escaped to England as a refugee after Hanover was invaded by the French army in 1757. During the next few years, he supported himself by offering music lessons and playing for hire in local orchestras. Herschel sent for his younger sister Caroline to join him in England in 1772 after the death of their father. She was originally to work as a housekeeper, but as William’s interest in astronomy grew, so did her household role and soon included that of note-taker to his observations. Herschel started his own astronomical observations journal in 1766, and his interest only grew from there. He spent hours reading books on star tables and astronomical calculations. He started to amass a small wealth of refractor telescopes, but was disappointed in the range they offered. He found that they provided mostly grainy or distorted images of the moon or close planets but not much else. Herschel began to revisit Newton’s reflector telescope. These telescopes were designed to concentrate light thanks to a concave mirror, which offered much higher magnification power. Newton’s model, however, was only six inches long; Herschel, driven by his own curiosity, imagined building a much larger reflector that could perhaps serve as an accurate observational tool for deep space and star gazing. A concave mirror of the size Herschel imagined had not yet been developed. Herschel decided to build one himself, and to create the right surface, would cast his own metallic mirror.

Working with Nebulae and Binary Stars

During his quest for the proper materials, Herschel came into contact with John Michell, a retired astronomer who is now credited with being the first to study what would become the modern conception of black holes. In a letter to British scientist Henry Cavendish in 1784, Michell discussed the possible effect that gravity might have on light and even proposed an early idea of a black hole, or a mass that would trap light due to its density. Due to the correspondence between Herschel and Michell, it is often presumed that Michell’s theories on black holes may have influenced some of Herschel’s work on double stars. William Herschel worked to create a catalogue of nebulae, and was the first to prove that most double stars were more than just optical illusions- they were what is called binary stars, or a star system made up of two stars which orbit their shared center of mass. This was an important discovery in that it proved the validity of Newton’s laws of gravity, even in space. Herschel began to catalogue his discovered double stars, and recorded over 700 of them. Binary stars typically contain either a white dwarf, a neutron star, or a black hole.

Lasting Legacy and Continued Research

William Herschel discovered the Spindle Galaxy, or NGC 3115, on February 22, 1787. NGC 3115 is roughly 32 million light-years away from the Milky Way. In 1992, John Kormendy and Douglas Richstone, of the Universities of Hawaii and Michigan, respectively, announced the existence of a supermassive black hole in the center of the Spindle Galaxy. It was estimated that the black hole was two billion times the mass of the Sun. Herschel’s son, John William Herschel, was the first to recognize Omega Centauri as a globular cluster, rather than a nebula, in the 1830s. As recently as April 2008, astronomers believe to have found an intermediate-mass black hole in the center of the cluster. The William Herschel Telescope, named in tribute to the astronomer, was opened on the Canary Islands in 1987. One of the major discoveries found using the WHT was a pocket of expanding gasses in the center of the Milky Way, which suggests the existence of a supermassive black hole.

The Romantic Period and Romantic Sciences

The second scientific revolution in Britain in the late eighteenth century is what has come to be known the era of Romanticism in science. That second revolution was marked by (2) the major critical movements of the period, all endeavors of understanding, which all affected the arts and sciences. This is clear in the case of the essential philosophies of the time, which look at the spectrum of knowledge based on the capabilities of both nature and human thought. Romantic views of the relationship between self and nature were the framework for the romantic approach to the sciences. The Romantics viewed the highest state of being to be a “state of the highest simplicity in which through the mere organization of nature… our desires are in tune with each other and with our powers and with everything to which we are related.” (3) The leading method for achieving this unity as heralded by the Romantics was through poetry and aesthetics. Romantics viewed the mechanistic natural philosophy of the Enlightenment as the result of the analytical approach responsible for our Fall from Grace with nature. (4) In a letter to William Wordsworth, a celebrated Romantic poet, fellow poet Samuel Taylor Coleridge writes of ‘the philosophy of mechanism, which, in everything that is most worthy of the human intellect, strikes Death.' Yet even this nihilistic take on the Enlightenment approach must be understood; on reading mechanist Newton’s Optiks, Coleridge describes ‘the beauty and neatness of his experiments, and with the accuracy of his immediate deductions from them.’ Though the Romantics find that the natural philosophy of the Enlightenment exemplifies the approach responsible for Man’s disconnect with nature, they are also view those methods as a stepping-stone for the new way of thinking. (6) There were a wide range of Romantic disciplines, including cosmology; evolution; biology; psychology; experiments on electricity and magnetism; geology, and more. Romantic science was also unique in that it had an aim of educating the general public. For the first time, scientific lectures and laboratory demonstrations were made open to the public, science textbooks were widely available and science was being taught to grade schools, and the experiment-based scientific method became the standard secular approach to science. Due to the new opportunities for scientific achievement and learning available to the public, new scientific institutions were founded and the monopoly of royal scientific societies came to an end as well. Romanticism as a movement was loosely structured along two ideas unique to the period. The first is the so-called Newton Syndrome, a concept based on the idea that there may exist a few scientific savants and that these few talented individuals are the ones who make the largest strides in advancing science. The second being the “Eureka! Moment,” or the idea that great discoveries take place in an instant, often by accident, for example while researching something else. These two philosophies help to humanize scientific discovery, while simultaneously celebrating great genius.

External links

Cunningham, Andrew and Jardine, Nicholas. Romanticism and the Sciences. Cambridge, UK: Cambridge University Press, 1990.

Holmes, Richard. The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science. New York, NY: Pantheon Books, a division of Random House, Inc., NY, 2008.

Soderqvist, Thomas. The History and Poetics of Scientific Biography. Burlington, VT: Ashgate Publishing Company, 2007.

Frommert, Hartmut and Kronberg, Christine. "John Michell (1724- 1793)". Students for the Exploration and Development of Space. February 07, 2010 <http://seds.org/Messier/xtra/Bios/michell.html>.

van der Marel, Roland. "Black Holes in Globular Clusters". Space Telescope Science Institute. February 07, 2010 <http://www-int.stsci.edu/~marel/m15release.html>.

Benn, Chris. "William Herschel Telescope". Isaac Newton Group of Telescopes. February 07, 2010 <http://www.ing.iac.es/Astronomy/telescopes/wht/>.

Kormendy, John and Richstone, Douglas, "Evidence for a Supermassive Black Hole in NGC 3115". The Astrophysical Journal 1992 July 10: 559.

Abrams, Meyer Howard. Natural Supernaturalism: Tradition and Revolution in Romantic Literature. New York, NY: W.W. Norton & Company, Inc., 1971. Pp. 144.