Chris

[Chris @honorschris]

A 59-year-old conjecture in fusion physics just fell.

Harold Grad (1967): smooth 3D plasma equilibria can't exist unless pressure is constant or there's symmetry.

This week: 3 families of counterexamples. 2 independent papers, posted a day apart. Two found with GPT-6 Astra.

Huge for stellarators.

[Chris @honorschris]

@tuhmeytow we can but this object is stellarator symmetric so it would look the same XD

[Chris @honorschris]

@foogotta yes! or at least the barrier has been lifted :)

[Chris @honorschris]

@even hahah very well put

[Chris @honorschris]

@n74148970 you are note wrong!

[Chris @honorschris]

@CryptoTetsugan same!

[Chris @honorschris]

@totti0223 you are asking the important question.

[Chris @honorschris]

@itsolelehmann what a time to be alive!

[Chris @honorschris]

@Whatevers322 @grok @proximafusion very positive

[Chris @honorschris]

A 59-year-old conjecture in fusion physics just fell.

Harold Grad (1967): smooth 3D plasma equilibria can't exist unless pressure is constant or there's symmetry.

This week: 3 families of counterexamples. 2 independent papers, posted a day apart. Two found with GPT-6 Astra.

Huge for stellarators.

[Chris @honorschris]

@bo0sti plasma go brrrr

[Chris @honorschris]

@zin___43 what a time to be alive!

[Chris @honorschris]

@prz_chojecki beautiful result/extension! We will have to add this to benchmark for numerical codes as well :) We will keep you updated

[Chris @honorschris]

@is_OwenLewis Thanks Owen! I will post more about fusion / AI! Let me know if you would like to see anything specific :)

[Chris @honorschris]

@mindcreek It will actually be the opposite! this gives another confidence that stellarator is not "necessarily" a bad fusion reactor design.

[Chris @honorschris]

@ThinkDi92468945 @grok As always Grok did good but spewed out jargons. I will take a stab at it @ThinkDi92468945. Stellarators are a type of fusion reactor(MCF like tokamak). For concrete application, these counter examples can now be used to benchmark existing code like DESC/VMEC/SPECTRE.

[Chris @honorschris]

Andrew did a great job explaining but I will take a stab at it too. 60 years ago Grad chose violence and said there's no nested surface(necessary for confinement) in stellarator -> stellarator researcher lost sleep at night but continued on -> researchers alongside AI found counterexamples. Now stellarator researchers can sleep better at night.

[Chris @honorschris]

grok does a good job! here's my 2c: grad woke up one day and chose violence "I bet there's no smooth 3d MHD equilibria with nested flux surface." Nested flux surface is a necessary condition for good confinement. Now these family of counterexamples give some comfort for stellarator community.

[Chris @honorschris]

@TFWNicholson I hope Terry is happy!

[Chris @honorschris]

@kentosho there has been major private($1B+) / public funding(https://t.co/Ts9dai12Rl) going to helical reactor (i.e. stellarator).

[Chris @honorschris]

@MrBunny1082519 it helps specifically stellarators but potentially tokamak too as real tokamaks with ripple are not necessarily axisymmetric.

[Chris @honorschris]

@realdrewcarson Always great to come back to this.