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The next day Infeld went to Einstein and told him that he (Infeld) had found a mistake in the calculation, and that he believed that gravitational waves do exist. Einstein replied that he too had found a mistake in his paper with Rosen that had been submitted to The Physical Review. It was less trivial than Infeld's mistake in the two pages where he had tried to prove that gravitational waves do not exist, and more difficult to detect. Einstein had come to the same conclusion as Infeld's, namely that gravitational waves do in fact exist; and with Robertson's help (still not knowing it was Robertson who had reviewed and remarked on Einstein's submission to The Physical Review) he finally corrected his Einstein-Rosen submission paper (Weinstein 2015, 261-264).