By 2025, net-gain nuclear fusion will be working at prototype scale.

True: by 31 December 2025, a fusion device produced net energy gain (fusion energy out greater than energy in, with at least target gain Q>1) in a working prototype or experimental facility, documented by the operator and credible reporting. For example, the US National Ignition Facility's December 2022 ignition result (target gain >1) and later repeats count as target-gain net gain at experimental scale. Mostly true: target-level net gain shown at an experimental facility, but only in single-shot experiments where 'working prototype' is a stretch. Mixed: not used here, since the claim names a single outcome. Mostly false: progress reached high fusion yields or records but not net gain by end-2025, or net gain was reached only after 2025. False: no fusion device had achieved any form of net energy gain by end-2025.

Set before the research began.

1. E1 Achieving Fusion Ignition | Extreme Light, Matter, and Fusion Lawrence Livermore National Laboratory (LLNL), Extreme Light, Matter, and Fusion · 29 September 2026

   “The NIF experiment on Dec. 5, 2022, far surpassed the ignition threshold by producing 3.15 megajoules (MJ) of fusion energy output from 2.05 MJ of laser energy delivered to the target.”

2. E2 Achieving Fusion Ignition | Extreme Light, Matter, and Fusion Lawrence Livermore National Laboratory (LLNL), Extreme Light, Matter, and Fusion · 29 September 2026

   “Oct. 1, 2025: LLNL achieved ignition at NIF for a 10th time with an experiment that generated a yield of 3.5 MJ, with a measurement uncertainty of +/- 0.17 MJ. NIF's lasers delivered 2.065 MJ of laser energy to the target, producing a target gain of 1.74.”

3. E3 Achieving Fusion Ignition | Extreme Light, Matter, and Fusion Lawrence Livermore National Laboratory (LLNL), Extreme Light, Matter, and Fusion · 29 September 2026

   “April 7, 2025: The eighth ignition experiment set new records for both energy yield and target gain. NIF achieved a yield of 8.6 MJ with a measurement uncertainty of +/- 0.45 MJ. NIF's lasers delivered 2.08 MJ of energy to the target in a 456-terawatt peak power pulse, producing a target gain of 4.13.”

4. E4 Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria arXiv (authors Samuel E. Wurzel and Scott C. Hsu, Fusion Energy Base and Lowercarbon Capital) · May 2025

   “Shot N221204 crossed this threshold, achieving Qsci = 1.5.”

LLNL reports that NIF's 5 December 2022 shot produced 3.15 MJ of fusion energy from 2.05 MJ of laser energy delivered to the target (E1). It also reports repeat ignition shots within 2025, including a target gain of 4.13 on 7 April 2025 and 1.74 on 1 October 2025, the tenth ignition (E2, E3). An independent arXiv analysis also reports scientific gain above 1 for the 2022 shot (E4). The resolution criteria name the NIF result and its later repeats as an example of what counts as true, so target gain above 1 was reached by the end-2025 deadline.