On March 23rd 1989 Martin Fleischmann and Stanley Pons stunned the world by announcing that had achieved fusion at room temperature on a table-top chemistry experiment - so called "cold fusion". This experiment involved conducting electricity through heavy water and into solid palladium metal (electrolysis) - something that a high school student could in principle do. This was not the first time such claims were made. In 1927, Swedish scientist J. Tandberg also claimed that he had fused hydrogen into helium in an electrolytic cell with palladium electrodes .
Despite the apparent simplicity, the experiments were difficult to reproduce and took 10 weeks to perform. Experimental replications were made over many months in reputable labs, e.g. Los Alamos and SRI international, but failed replication attempts done over several days at MIT and Caltech were more influential. They added to an already growing criticism of the poor communication and high ambiguity of some of the initial results.
As for a possible mechanism for cold fusion, not only did fusion physicists consider it impossible to produce useful amounts of fusion at low temperatures, but the expected fusion radiation would have killed anyone in the lab. Reasonable scepticism turned into dogmatic opposition where cold fusion scientists were ridiculed in public and accused of being incompetent, delusional and fraudulent.
Despite the words of Nobel prize winner and theoretical nuclear physicist, Julian Schwinger, who cautioned "The circumstances of cold fusion are not those of hot fusion" , the community had made up its mind. Mainstream journals quickly stopped accepting cold fusion papers for review and research drifted into the fringe.
Today, cold fusion research is often called Low Energy Nuclear Reactions (LENR). Reports of anomalies in metal-hydrogen system continue to accumulate and, although not all of those reports live up to scientific standards, collectively they represent a body of formal and informal knowledge not to be ignored. It now appears that:
Despite this progress, we still don't have a fully reproducible experiment - why? We can look to the early days of the transistor for a possible answer. There were plenty of solid-state amplification anomalies reported in amateur radio magazines throughout the early 1920s. However, the development of the transistor only proceeded apace 20 years later when a quantum theory of conduction was available to guide experiments and the required high purity materials could be conveniently produced.
30 years on, cold fusion appears to be in a similar place. Advances in theory at the intersection of quantum dynamics, nuclear physics and nanoscience (we call it Solid State Nuclear Science) is providing a plausible physics mechanism for cold fusion and routine nano-scale engineering of materials is fast approaching.
The overall aim of this research is to progress solid-state nuclear science as quickly as possible. To this end, I co-founded an open science platform Project Ida which attempts to amplify our efforts by bring together the vast wealth of experience and resources that already exist in the scientific community.
I also built my own experiment from scratch which you can read more about at the end of the technical section below.
More technical details
The central idea of the earliest experiments of Tandberg , and also Paneth and Peters , was to create a condition of very high hydrogen (or deuterium) density by using the special ability of palladium to act like a “metal sponge” for these gases . The hope was that the hydrogen (or deuterium) would be close enough for fusion to occur at room temperature.
It was already known that the hydrogen-hydrogen distance in molecular hydrogen at room temperature was 74pm and so the hydrogen inside palladium would have to be at least this close. It was not until 1957 that neutron diffraction experiments could reveal the position of hydrogen inside the palladium lattice . Hydrogen was found at the octahedral sites of the palladium face centred cubic lattice - putting the hydrogen-hydrogen distance at 200pm. This made it seem highly unlikely that fusion would be possible in palladium hydride.
Interest in cold fusion was revived by the Fleischmann and Pons announcement in 1989 . The controversy notwithstanding, physicists were stimulated to look again at the fusion rates models used since 1920s (in particular the Gamow model ). It was found that:
There is still a "missing" 20 orders of magnitude to find in models in order to explain the anomalies that have been observed. Finding these missing orders of magnitude is what I spend most of my time on today.
My focus is on theory and modelling of the quantum dynamics aspects of the cold fusion problem and specifically on nuclear excitation transfer. I am working with a theory that's been developed over the last 20 years which provides a plausible location for the missing orders or magnitude. I publish computational essays on these subjects on the Project Ida research page and also Project Ida GitHub
Although today I am doing more theory and modelling, my initial research interest in cold fusion was experimental. Challenged by one of my physics friends to build a cold fusion demonstration for under £1000, I decided to attempt to replicate the work of Les Case [7-9]. He made cold fusion / LENR happen in a pressurised container of deuterium gas at 3.4 atmospheres at 200C with palladium and coconut shell carbon. I publish all my lenr work openly on a GitLab repository called lilley-lenr. There you'll find my data, analysis code. You can also follow the real-time progress of my experiments by visiting the experimental blog and watch video updates on my YouTube channel
 J. Tandberg, “Method for producing Helium,” Swedish patent application (1927). Due to Paneth and Peters'  retraction, Tandberg's patent application was denied eventually.
 F. Paneth and K. Peters, “Uber die Verwandlung von waterstoff in Helium,” Naturwissenschaften, 14, 958 (1926) . P&P reported transformation of hydrogen into helium when hydrogen was absorbed by finely divided palladium at room temperature. The authors later acknowledged that the helium they measured was due to background from the air.
 T. Graham XVIII. On the absorption and dialytic separation of gases by colloid septa. Philosophical transactions of the Royal Society of London, 156, 399-439 (1866) . "Palladium ... readily absorbs hydrogen, to the extent of upwards of 600 times the volume of the metal..."
 M. Fleischman S. Pons, "Electrochemically induced nuclear fusion of deuterium", Journal of Electroanalytical Chemistry and Interfacial Electrochemistry Volume 261, Issue 2, Part 1, Pages 301-308 (1989)
 G. Gamow Zur Quantentheorie des Atomkernes Zeitschrift für Physik volume 51, pages 204–212(1928), English translation here.
 P. Hagelstein et.al, Appendix B Results of Case Experiments at SRI (2004). (This was Submitted to DoE as part of their second review on LENR)