Fusion is the reaction that powers the Sun, and for seventy years it's been the great dream of clean energy — limitless fuel, no carbon, no long-lived waste. It's also famously "always thirty years away." We explain what fusion actually is, why it's so fiendishly hard to do on Earth, what recent milestones did and didn't achieve, and why the optimism and the caution are both justified.

You'll come away understanding the difference between fusion and fission, why you have to build a machine hotter than the Sun's core, what "ignition" and "net energy" really mean, and why fusion is a genuine hope rather than a con — but not a quick one.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: ITER (iter.org); the US National I ...