In 1936, America’s foremost physics journal, the *Physical Review*, received an intriguing paper entitled *Do Gravitational Waves Exist?* from Albert Einstein and his colleague Nathan Rosen.

The paper was a follow-up to Einstein’s historic breakthrough in 1915, when he revealed equations showing how mass and energy cause space-time to curve and how mass and energy respond to this curvature – in other words, the general theory of relativity. In 1916, Einstein augmented the theory with a prediction of the existence of gravitational waves which travel at the speed of light.

Einstein wasn’t the first to propose the existence of gravitational waves – they were first proposed 25 years earlier by Oliver Heaviside, who drew an analogy with James Clerk Maxwell’s theory of electromagnetic waves to discover wave equations for gravity. (It was Heaviside who formulated the vector calculus form of Maxwell’s equations we use today.)In 1917, Einstein said our universe is static – neither expanding nor contracting. He had discovered this universe as a solution to his own relativity equations. The tantalizing beauty of these equations is that they actually have any number of solutions, each describing a different universe. Soon Willem de Sitter, Alexander Friedmann, and Georges Lemaître discovered alternative universes that also satisfied Einstein’s equations.

Back now to Einstein and Rosen’s paper, *Do Gravitational Waves Exist?* which they submitted in 1936 to the *Physical Review*. In it they announced their discovery of a fascinating new solution to Einstein’s equations, describing a universe with the symmetry of a cylinder and gravitational waves that seemed to ripple through it. Einstein and Rosen decided these waves were a fiction generated by mathematical procedures and were not physically real.

Rather than publish the paper, the *Physical Review’s* editor John Tate sent it to an anonymous peer reviewer, who we now know was Howard Robertson.

### Dear Professor Einstein, Please Think Again

Robertson read *Do Gravitational Waves Exist?* carefully and reported back to Tate on 10 typed pages that Einstein & Rosen were in error. He said the gravitational waves described in their paper were real physical waves, not mathematical quirks. He asked the authors to think again.

Einstein had been in America for three years. In Europe, he was used to having his papers published without question and he was riled by the request to revise his work. Quickly he sent a letter to the *Physical Review’s* editor, John Tate:

Einstein was as good as his word, sending the paper to the *Journal of the Franklin Institute* with the new title *On Gravitational Waves*.

Soon after this vexing incident, Einstein’s assistant Leopold Infeld, who had replaced Nathan Rosen, bumped into Howard Robertson. Unaware Robertson was the anonymous reviewer who had suggested his boss should think again about gravitational waves, the two began chatting about cosmology in general and about gravitational waves in particular.

Robertson persuaded Infeld that Einstein & Rosen were wrong, that their paper needed to be reformulated, and that gravitational waves were physically real. Infield returned to the Master, who now gave a fair hearing to the very arguments he had rejected when sent to him by the *Physical Review*. Howard Robertson then spoke to Einstein with the result that Einstein & Rosen’s paper was:

*Physical Review*, February 1937

Einstein contacted the *Journal of the Franklin Institute* urgently to correct the mistakes.

In the edited paper, Einstein acknowledged that he and Rosen had originally interpreted their results incorrectly and added a note of thanks to the man who had proved him wrong:

Einstein never found out that Howard Robertson was the *Physical Review’s* anonymous referee. On reflection, Einstein must have realized that the referee had given him good advice. However, he seems to have never forgiven the *Physical Review*, and he never submitted another paper to it.

Although physicists were sure for a long time that gravitational waves must exist, it took 122 years to detect them after Heaviside’s first suggestion. Rainer Weiss, Kip Thorne, and Barry Barish shared the Nobel Prize in Physics for this achievement in 2017.

### Who Was Howard Robertson?

Howard Percy Robertson was born on January 27, 1903, in Hoquiam, Washington, USA. His father, George Duncan Robertson, was an engineer. His mother, Anna McLeod, was a nurse.

Robertson graduated from the University of Washington in Seattle with a B.S. in mathematics in 1922, and a year later with an M.S. in mathematics and physics.

He moved south to Caltech, where he earned a Ph.D. in mathematics and physics, authoring a thesis entitled: *On Dynamical Space-Times Which Contain a Conformal Euclidean 3-Space*.

### Göttingen

Robertson carried out his post-doctoral research in Germany, mainly at the University of Göttingen, which was then the world’s center of mathematics. At Göttingen he met some of the world’s greatest mathematicians and physicists including David Hilbert, Albert Einstein, Werner Heisenberg, Erwin Schrödinger, John von Neumann, and Eugene Wigner.

### Professor

Back at Caltech Robertson was appointed assistant professor in 1928, before moving to Princeton in 1931 as an associate professor. He was appointed full professor in 1938.

A virtuoso in quantum mechanics, general relativity, and cosmology, Robertson argued that we live in an expanding universe.

### Wartime Work

After America entered World War 2, Robertson moved to the UK’s capital, London, where he worked on methods of scrambling enemy radar signals. He was awarded the United States’ highest civilian honor, the Medal of Merit, for his work.

### Caltech and UFOs

In 1947, Robertson returned to Caltech, where he spent the rest of his career.

In 1953, he chaired the Robertson Panel, which investigated the large number of UFO reports being made at the time, concluding that in all likelihood the reports were all explicable as natural phenomena or mistaken interpretations of everyday aerial objects.

### The End

Howard Robertson died age 58 on August 26, 1961. He was survived by his wife Angela (née Turinsky) and their children George and Marietta.

**Further Reading**

Oliver Heaviside

A Gravitational and Electromagnetic Analogy, Part 1

The Electrician, Vol. 31, pp. 281-282, 1893

Oliver Heaviside

A Gravitational and Electromagnetic Analogy, Part 2

The Electrician, Vol. 31, p. 359, 1893

A. Einstein, N. Rosen

On gravitational waves

Journal of the Franklin Institute, Vol. 223, No. 1, pp. 43-54, January 1937

Daniel Kennefick

Einstein Versus the Physical Review

Physics Today, September 2005

John D. Barrow

The Book of Universes: Exploring the Limits of the Cosmos

W. W. Norton & Company, June, 2012

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