The Perfect Theory (37 page)

Throughout the day, as festivities continued in Príncipe, Einstein's and Eddington's names were on everyone's lips. In this lost corner of a minuscule island, it was too much to ask that anyone would actually know what we were talking about. Ponderous nods from the local and visiting dignitaries didn't mean much, and a shoal of children and teenagers ran around during the ceremony. They didn't know what it was about, true, but they had of course heard of Einstein. And some even knew about the famous Englishman Eddington who had come to visit many years ago. They all agreed that it was a good thing—that small island's claim to fame.

As I watched the crowd joining in this odd, esoteric celebration, I saw it as yet another quirky sign of how universal and democratic Einstein's theory has become. While tortuous and often intractable, Einstein's theory has been at the same time democratic, easily encapsulated in a few pages of condensed equations. The history of general relativity spans many continents, with a full cast of characters that is truly international and varied. British astronomers, a Russian meteorologist, a Belgian priest, a New Zealander mathematician, a German soldier, an Indian child prodigy, an American expert on the atom bomb, a South African Quaker, and so many more have been brought together by the elegance and power of Einstein's theory.

That night, we handed out telescopes to the crowd and looked up at the stars. The sky was breathtaking, ready to offer up much more that would help us delve deeper into Einstein's theory. I thought of how, even now, Einstein's theory was driving us to look out into the cosmos on a grander scale. The new Príncipe might now be in the south of Africa or in the Australian desert, and the new telescope would use the latest, most powerful technologies of the twenty-first century.

While Eddington had used an optical telescope, something with a lens, an eyepiece, and a photographic plate, this new phase will rely on radio antennas and dishes. Radio has already given so much to general relativity, but this time it will go much further than has ever been envisaged. The idea is to build a collection of tens of thousands of radio antennas scattered across hundreds and thousands of kilometers. Known as the Square Kilometer Array, or SKA, because the total collecting area of all the antennas should add up to a square kilometer, it will take one, possibly two continents to support it. Some of the telescopes will lie out in the vastness of the Australian west, and others will be strewn throughout southern Africa. The core of the beast will be laid out in the Karoo Desert, but a number of these dishes will be scattered throughout the continent in places like Namibia, Mozambique, Ghana, Kenya, and Madagascar. It will be a truly continental,
African
endeavor. And, in the same way that Eddington used Príncipe to establish general relativity, the SKA would be the beast that could test Einstein's theory on cosmological scales with unprecedented precision. The SKA would detect if there were, indeed, any cracks in Einstein's grand idea. It would be able to detect the elusive gravitational waves that are still out there, waiting to be discovered. It might even reveal the nature of the infamous dark energy that seems to have cemented itself into the current model of the universe.

That night as we celebrated Eddington's and Einstein's colossal achievements, I thought about how we are only at the beginning of what the theory of spacetime is going to tell us about the universe. The twenty-first century is surely going to be the century of Einstein's general theory of relativity, and I feel fortunate to be living at a time when so many new things are waiting to be discovered. Almost a hundred years after Einstein finally came up with his theory, something fantastic is going to happen.

Two people made this book happen. Patrick Walsh convinced me, and gave me the opportunity, to write about this obsession of mine. Courtney Young took my manuscript and, with remarkable grace and firmness, made it into something I would want to read.

I have relied on testimony, advice, and criticism from a long list of colleagues, friends, family, readers, and writers over many years. Here is an attempt at a (quite possibly incomplete) list: Andy Albrecht, Arlen Anderson, Tessa Baker, Max Bañados, Julian Barbour, John Barrow, Adrian Beecroft, Jacob Bekenstein, Jocelyn Bell Burnell, Orfeu Bertolami, Steve Biller, Michael Brooks, Harvey Brown, Phil Bull, Alex Butterworth, Philip Candelas, Rebecca Carter, Chris Clarkson, Tim Clifton, Frank Close, Peter Coles, Amanda Cook, Marc Davis, Xenia de la Ossa, Cécile DeWitt-Morette, Mike Duff, Jo Dunkley, Ruth Durrer, George Efstathiou, George Ellis, Graeme Farmelo, Hugo and Karin Gil Ferreira, Andrew Hodges, Chris Isham, Andrew Jaffe, David Kaiser, Janna Levin, Roy Maartens, Ed Macaulay, João Magueijo, David Marsh, John Miller, Lance Miller, José Mourão, Samaya Nissanke, Tim Palmer, John Peacock, Jim Peebles, Roger Penrose, João Pimentel, Andrew Pontzen, Frans Pretorius, Dimitrios Psaltis, Martin Rees, Bernard Schutz, Joe Silk, Constantinos Skordis, Lee Smolin, George Smoot, Andrei Starinets, Kelly Stelle, Francesco Sylos-Labini, Kip Thorne, Neil Turok, Tony Tyson, Gisa Weszkalnys, John Wheater, Adam Wishart, Lukas Wilowski, Andrea Wulf, and Tom Zlosnik. While their contributions have been invaluable, any errors or misconceptions in the final text are my own.

The team at Conville and Walsh have been incredibly supportive in seeing this book through, and my colleagues at the University of Oxford have been enthusiastic and helpful. It is a real privilege working with them all.

One of the joys of writing this book has been reading many of the original papers and articles on general relativity as well as histories, biographies, and memoirs. I hope the specific sources that follow will be taken as encouragement for further reading in the subject. It is definitely worth the effort. Full references for the publications cited in this section can be found in the bibliography.

I highly recommend plowing through some of the scientific literature, even if you don't have the background to understand much of what is being done. It will give you a real flavor of what science is about, how things are presented, explained, and promoted, and how the vast cast of characters interact with each other through the scientific journals. Unfortunately, many of the journals are behind “paywalls,” and some of the articles I refer to here cannot be accessed if you are not in an academic institution. A surprising number of them can, however, and I suggest you look for them. I recommend using one of the following search engines:

http://scholar.google.com

http://inspirehep.net

http://adsabs.harvard.edu/abstract_service.html

Each one has its own syntax, but collectively they will help you find any of the articles you might be looking for. The scientific community in astronomy, mathematics, and physics has, for the past two decades, posted freely available copies of articles at a repository on
http://arxiv.org
. Wherever possible, I have listed the link a given paper has to that website.

Finally, I interviewed a few of the protagonists for this book; in the notes that follow, I explicitly identify quotes that came from those interviews.

 

Prologue

 

The description of A. Eddington's encounter with L. Silberstein is described firsthand in Chandrasekhar (1983). You might want to venture onto the “gr–qc” section of
ArXiv.org
to see the kind of weird but sometimes wonderful stuff that pops up in the field of relativity.

 

1.
IF A PERSON FALLS FREELY

 

So much has been written about Einstein that I have been spoiled for choice. I have used a handful of superb biographies to guide me through his life. Fölsing (1998) is very detailed, nuanced, and richly documented. Isaacson (2008) captures the essence of the man, bringing real color to his life and times. Pais (1982) is a classic, focusing on his work and mapping out many of the mathematical and physical steps that led to his great discoveries.

As a panorama of physics at the beginning of the twentieth century, there is Bodanis (2001), a wonderful piece of narrative history, focusing on the lead-up to, and consequences of, Einstein's famous
E
=
mc
2. Bodanis (2006) offers real insight into how Maxwell and his contemporaries transformed the world with their work on electricity and magnetism. Baum and Sheehan (1997) walk us through the beginning of the end of Newtonian gravity and Le Verrier's ill-fated quest for the planet Vulcan.

There is a whole world of Einstein scholars out there. John Norton, John Stachel, and Michel Janssen, to name a few, have all really tried to get into his mind, spelling out his successes and failures. It is a rich literature that can really suck you in. Those who want a firsthand look at his discoveries, especially his miraculous year of 1905, should have a look at Stachel (1998), a compilation of his papers. Einstein's first step in his quest for general relativity, the article for the
Yearbook,
is well worth a look, but it is probably easier to read a more gentle description in Einstein (2001).

 

[>]
“When you pick up an application”: F. Haller, in Isaacson (2008), p. 67.

[>]
“You are a very clever boy”: H. Weber to Einstein, in Isaacson (2008), p. 34.

[>]
“considerably facilitates relations”: Einstein to W. Dällenbach, 1918, in Fölsing (1998), p. 221.

[>]
“asymmetries”: Einstein in Stachel (1998) and Pais (1982), p. 140.

[>]
Proust and Le Verrier: See Proust (1996).

Dickens and Le Verrier: See Dickens (2011).

[>]
“How could a planet”: Le Verrier, 1859, in Baum and Sheehan (1997), p. 139.

[>]
“If a person falls freely”: Einstein lecture in Kyoto, 1922, in Einstein (1982).

[>]
“My papers are meeting with much acknowledgement”: Einstein to M. Solovine, 1906, in Fölsing (1998), p. 201.
“I must confess to you that I was amazed”: J. Laub to Einstein, 1908, in Fölsing (1998), p. 235.

 

2.
THE MOST VALUABLE DISCOVERY

 

While Fölsing (1998) does a careful job of describing the context for the discovery of general relativity and how Einstein stumbled toward his final version, Pais (1982) provides the detail—the latter is very mathematical but also very rewarding. For Eddington I have relied heavily on three very different books. Chandrasekhar (1983) is a slim, respectful volume on his work and thought. Stanley (2007) addresses his more mystical and political stance and how he behaved during the First World War. Miller (2007) is a fantastic read where we get a sense of how complex Eddington was (and how difficult he would become later in life). A careful description of the eclipse expedition can be found in Coles (2001).

 

[>]
“You know, once you start calculating”: Fölsing (1998), p. 311.
“mathematically cumbersome”: H. Minkowski to his students, in Reid (1970), p. 112, and Fölsing (1998), p. 311.
“superfluous erudition”: Fölsing (1998), p. 311.
“Since the mathematicians pounced”: Ibid., p. 245.

[>]
“You've got to help me”: Ibid., p. 314.

[>]
“The gravitation affair has been clarified to my full satisfaction”: Einstein to P. Ehrenfest, in Pais (1982), p. 223.

[>]
“in the madhouse”: Einstein to H. Zangger, 1915, in Fölsing (1998), p. 349.
“the life or property”: Fölsing (1998), p. 345.

[>]
“educated men of all states”: Ibid., p. 346.

[>]
Meeting C. Perrine: Mota, Crawford, and Simões (2008).
“We can readmit Germany to international society”: H. Turner, 1916, in Stanley (2007), p. 88.

[>]
“Think, not of a symbolic German”: Eddington (1916).

[>]
“there has been between us something like a bad feeling”: Einstein to D. Hilbert, 1915, in Fölsing (1998), p. 376.
“the most valuable discovery of my life”: Einstein to A. Sommerfeld, 1915, in Fölsing (1998), p. 374.

[>]
“We have tried to think that exaggerated and false claims made by Germans”: H. Turner, 1918, in Stanley (2007), p. 97.
“under present conditions the eclipse will be observed by very few people”: F. Dyson, 1918, in Stanley (2007), p. 149.

[>]
“Through cloud. Hopeful”: Pais (1982), p. 304.

[>]
“Eclipse Splendid”: Ibid.
“the most important”: J. J. Thomson, 1919, in Chandrasekhar (1983), p. 29.

[>]
“Revolution in Science”:
The Times,
November 7, 1919.
“All Lights Askew”:
New York Times,
November 10, 1919.

[>]
“In Germany I am called a German man of science”: Einstein on his theory,
The Times,
November 28, 1919.

 

3.
CORRECT MATHEMATICS, ABOMINABLE PHYSICS

 

There is a wealth of information about the discovery of the expanding universe. The main papers can be found in the compilations of cosmological classics, a notable example of which is Bernstein and Feinberg (1986). I have avoided all discussion of “Mach's principle,” which pushed Einstein to formulate his static universe model, but you can find a discussion of the debate between Einstein and de Sitter in Janssen (2006). A detailed and well-documented history of the expanding universe is Kragh (1996) and more recently Nussbaumer and Bieri (2009). For individual and more detailed descriptions of the main protagonists in this chapter see Tropp, Frenkel, and Chernin (1993) for Friedmann, and Lambert (1999) and the article by A. Deprit in Berger (1984) for Lemaître. An entertaining description of Hubble and Humason can be found in Gribbin and Gribbin (2004), and the Humason AIP interview in Shapiro (1965) is hugely informative. For some of the controversy over who did what in the discovery of the expanding universe (and the underappreciated role that Vesto Slipher played) I recommend Nussbaumer and Bieri (2011) and Prof. John Peacock's homage to Slipher at
http://www.roe.ac.uk/~jap/slipher
.