Black Holes and Time Warps by Kip Thorne

Author:Kip Thorne
Language: eng
Format: mobi
Published: 2014-11-04T02:00:00+00:00

(a) Karl Jansky and the antenna with which he discovered, in 1952, cosmic radio waves from our galaxy, (b) Grote Reber, ca 1940. (c) The world’s first radio telescope, constructed by Reber In his mother's backyard In Wheaton, Illinois, (d) A map of radio waves from the sky constructed by Reber with his backyard radio telescope, £(a) photo by Bell Telephone Laboratories, courtesy A1P Emilio Segrfc Visual Archives; (b) and (c) courtesy Grote Reber; (d) is adapted from Reber (1944).]

(Figure 9.Id). In his maps one can see clearly not only the centra] region of our Milky Way galaxy, but also two other radio sources, later called Cyg A and Cas A—A for the “brightest radio sources,” Cyg and Cos for uin the constellations Cygnus and Cassiopeia.” Four decades of detective work would ultimately show, with high probability, that Cyg A and many other radio sources discovered in the ensuing years are powered by gigantic black holes.

The stoiy of this detective work will be the central thread of this chapter. I have chosen to devote a whole chapter to the stoiy for several reasons:

First, this stoiy illustrates a mode of astronomical discovery quite different from that illustrated in Chapter 8. In Chapter 8, ZeFdovich and Novikov proposed a concrete method to search for black holes; experimental physicists, astronomers, and astrophysicists implemented that method; and it paid off. In this chapter, gigantic black holes are already being observed by Reber in 1939, long before anyone ever thought to look for them, but it will take forty years for the mounting observational evidence to force astronomers to the conclusion that black holes are what they are seeing.

Second, Chapter 8 illustrated the powers of astrophysicists and relativists; this chapter shows their limitations. The types of black holes discovered in Chapter 8 were predicted to exist a quarter century before anyone ever went searching for them. They were the Oppenheimer- Snyder holes: a few times heavier than the Sun and created by the implosion of heavy stars. The gigantic black holes of this chapter, by contrast, were never predicted to exist by any theorist. They are thousands or millions of times heavier than any star that any astronomer has ever seen in the sky, so they cannot possibly be created by the implosion of such stars. Any theorist predicting these gigantic holes would have tarnished his or her scientific reputation. The discovery of these holes was serendipity in its purest form.

Third, this chapter’s story of discoveiy will illustrate, even more clearly than Chapter 8- the complex interactions and interdependencies of four communities of scientists: relativists, astrophysicists, astronomers, and experimental physicists.

Fourth, it will turn out, late in this chapter, that the spin and the rotational energy of gigantic black holes play central roles in explaining the observed radio waves. By contrast, a hole's spin was of no importance for the observed properties of the modest-sized holes in Chapter 8.

In 1940, having made his first radio scans of the sky, Reber carefully wrote up a technical description

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