Cold Fusion

Low Energy Nuclear Reactions (LENR, formerly cold fusion) refers to nuclear reactions allegedly occurring at near room temperature, contrasting with conventional fusion requiring millions of Kelvin. The 1989 Fleischmann-Pons announcement of excess heat from palladium-deuterium electrolysis ignited scientific controversy when results proved difficult to replicate.

Fleischmann-Pons Effect

The original 1989 experiment involved electrolyzing heavy water (D2O) using palladium electrodes, claiming to observe excess heat production beyond electrochemical processes. The researchers reported: sustained heat output exceeding electrical input; neutron emissions; and tritium production. However, replication attempts worldwide yielded mixed or null results, with mainstream physics rejecting the claims due to lack of neutron emissions, thermometry errors, and absence of theoretical mechanism.

LENR Research Continuation

Despite mainstream rejection, LENR research continues with reported excess heat anomalies from metal-hydrogen systems. Proposed mechanisms include: hydrogen loading in metal lattices creating localized fusion conditions; lattice-assisted nuclear reactions; and quantum tunneling effects enabling fusion at low energies. Some researchers claim electromagnetic transmutation—element transformation through high-voltage EM interference allegedly accessing zero-point energy (aluminum→silver, copper→gold, radioactive neutralization claims). Material analysis typically shows surface contamination rather than genuine nuclear transformation.

Acoustic Cavitation Fusion and Current Status

Acoustic Cavitation Fusion (Sonofusion)

Rusi Taleyarkhan and colleagues reported (2002-2004) neutron emissions from sonoluminescence experiments using deuterated acetone—claiming bubble collapse created fusion conditions. Sonoluminescence (sound-driven bubble implosion producing light flashes) achieves extreme conditions: ~10,000 K temperatures, >1000 atmosphere pressures. Taleyarkhan claimed deuterium nuclei in collapsing bubbles reached fusion energies—detecting neutrons, tritium, and gamma emissions. If validated, sonofusion would enable desktop fusion with modest acoustic power inputs. However, replication attempts yielded mixed or null results; investigations raised questions about detector calibration, background radiation, and contamination. By 2008 consensus emerged that positive results were artifacts.

Current Status

NASA, Airbus patents, and multiple startups maintain interest despite fringe status. Skeptics cite: lack of neutron emissions; thermometry errors; transmutation requiring MeV energies vastly exceeding equipment capabilities; and absence of theoretical framework explaining low-temperature fusion. Nevertheless, persistent research and occasional positive results distinguish LENR from pure pseudoscience—representing controversial fringe science where extraordinary claims meet limited experimental validation.