Over the next few months, scientists brought the most sophisticated and sensitive ​​experiments to bear on the questions of cold fusion, but were unable to find any ​​evidence in support of it. The case for cold fusion was not looking good. However, there was still the possibility that the finding couldn’t be ​​replicated — not because cold fusion wasn’t happening — but because other scientists weren’t matching the conditions of the original experiment exactly. Perhaps Pons and Fleischmann were doing something special in their experiment that they were not revealing or were not aware of themselves, and it was this “special something” that led to cold fusion. The best way to ​​test this would be to have independent experts search for fusion products coming from Pons and Fleischmann’s fusion cells. Many scientists offered to collaborate, but their offers were declined. Pons and Fleischmann were actively standing in the way of tests that could have shed light on whether or not their ​​hypothesis was correct.

After months with no resolution as to whether cold fusion was real, the scientific community began insisting that these tests be done. There is no governing body of science that could have forced Pons and Fleischmann to perform the follow-up tests; however, the scientific community can apply pressure to uphold the standards of good science by withholding esteem, funding, or jobs, and by being particularly skeptical of research performed with lax standards. Only after significant pressure from the scientific community did Pons and Fleischmann finally agree to perform the tests.

One follow-up study involved searching for helium-4, one of the products of the fusion reaction. Perhaps, it was reasoned, the searches for neutrons had come up empty because the helium was stuck in the palladium rods and was not releasing its excess energy as neutrons, but in another way. Pons and a group of other scientists decided to test for helium in five palladium rods, only one of which had been used in Pons and Fleischmann’s fusion cell. If fusion had indeed occurred, then only the fusion rod should have elevated helium levels. To reduce the possibility of bias influencing results, they decided on a “​​double-blind” study design. Pons would give the rods to an intermediary, who would distribute segments of all five rods to six different laboratories. Neither the intermediary nor the testing labs would know which rod was which, and Pons wouldn’t be able to unintentionally tip off the laboratories about it when he gave them the rods.

The six labs tested each rod segment for helium and gave their results back to the intermediary, who met with Pons to exchange the results and the rod information. Pons had initially agreed to reveal which rod had been used in a fusion cell at this time, but changed his mind and kept those details to himself. He reviewed the helium ​​data and saw that the fusion rod did not have elevated helium levels. The study did not support cold fusion.

While these results might seem cut-and-dried, Pons cast doubt on them when they were finally publicized. He explained that the particular fusion rod he’d submitted for helium analysis had not produced as much heat as he’d claimed at recent scientific conferences. This was problematic on several levels. If the rod hadn’t had much fusion going on in it, then that would explain why it didn’t have elevated helium levels. But then why did Pons sabotage the helium study by providing a bad rod? And why did he report such high levels of heat for his original fusion experiment? Was Pons manipulating the data?