[Space] The sun and a nuclear power plant run on opposite versions of the exact same underlying physics

[ElPresidente]

As you have probably worked out already I'm really really interested in space as as a hobby.

Every nuclear power plant operating today runs on fission, the process of splitting a large, heavy atom, typically uranium, into two smaller ones. A neutron slams into a uranium atom, splitting it apart and releasing a burst of energy along with additional neutrons, which then go on to collide with other uranium atoms, creating a self sustaining chain reaction that produces a steady, controllable source of heat used to generate electricity

Fusion is fission's opposite, instead of splitting a heavy atom apart, it combines two very light atoms together into a slightly heavier one, and this is the exact process powering the sun and every other star in the universe. The easiest fusion reaction to attempt on Earth combines two forms of hydrogen, deuterium and tritium, but doing this requires overcoming the powerful natural repulsion between two positively charged protons, which means heating the fuel to roughly 200 million degrees Celsius, around ten times hotter than the core of the sun itself, to force the reaction to occur

Fission is a mature, demonstrated technology already powering reactors around the world, from massive multi gigawatt power plants down to compact reactors small enough to fit inside a submarine. Fusion, despite producing about four times more energy per unit of mass than fission and generating far less long lived radioactive waste, remains almost entirely experimental, since achieving and sustaining those extreme temperatures in a controlled, net energy positive way on Earth has proven to be an extraordinarily difficult engineering problem that decades of research have still not fully solved

Fission and Fusion: What is the Difference?www.energy.gov

[Coder65]

Fusion requiring temperatures ten times hotter than the sun's own core is such a wild number, that alone explains why this has remained experimental for so many decades

[Coder58]

Splitting versus combining as the core distinction is genuinely the cleanest possible way to explain the difference, everything else follows from that one basic contrast

[Blake_73]

Fission already powering everything from massive plants down to submarine reactors while fusion remains purely experimental really highlights just how much harder fusion actually is despite decades of hype

[Debbie]

Four times more energy per unit of mass than fission is a compelling number, no wonder so much research money keeps chasing fusion despite the immense engineering difficulty

[Kayla73]

The natural proton repulsion being the actual physical obstacle fusion has to overcome makes the extreme temperature requirement make complete intuitive sense rather than feeling arbitrary

[Keane]

Good reminder that fusion producing far less long lived radioactive waste than fission is a real, meaningful advantage on top of the energy density, if we can ever actually achieve it reliably

[Florence19]

This is exactly the kind of clean, accurate primer that should exist before every single fusion breakthrough headline that inevitably generates confusion about how close we actually are

[VoidKnight]

Appreciate the honest framing that decades of research still have not fully solved this, that tempered expectation feels more accurate than the more breathless fusion coverage that shows up periodically

[Daemon90]

The sun itself being cited as a working example of fusion happening constantly right above our heads is such a good grounding detail for an otherwise pretty abstract physics concept