Because sustainable positive energy out has never been achieved before in 60 years of research. This is gigantic. It’s potential to decarbonize the world is massive, and now it became a whole lot less theoretical.

It’s an incredible milestone, not a solved problem.

It's a common joke that fusion power is always 50 years away. With this milestone, is it finally less than 50 years away?

That's a circular argument. It's big because the people doing it call it big. Why should I, an outsider, care about their internal goals, their egoes, or their status in their field? What does it do or imply for me?

To achieve fusion for power production, you need more output than input. For 60+ years this hasn’t been achieved in a replicated fashion. Now it has, and it’s 50% more power rather than 0.1% more power as was sometimes shown for 2 nanoseconds before. So now we know fusion for power is possible. If it can be scaled successfully (now likely not an if anymore, but a function of time), then we have the ability to have clean and safe energy 24/7. That would help mitigate the worst of climate change, and if cheap, turbocharge the entire economy.

What’s the circle or not big milestone here?

The issue is, we've been able to get more energy out of a fusion reaction than put in for 60-70 years now. The H-Bomb is very good at doing that. You will say, yeah, but an H-Bomb is a one time use thing, and it has a habit of destroying everything. If you look into how the second stage of an hbomb is speculated to work, its pretty much identical to this experiment, that is by design, not by accident.

From https://www.nature.com/articles/d41586-022-04440-7

Herrmann acknowledges as much, saying that there are many steps on the path to laser fusion energy. “NIF was not designed to be efficient,” he says. “It was designed to be the biggest laser we could possibly build to give us the data we need for the [nuclear] stockpile research programme.”

*contained fusion

I'm asking why this somewhat arbitrary line being crossed is something I should care about. It doesn't imply fusion will reach a state of practical application. Why is this more exciting that achieving a ratio of .1, or .5, or 2, or 10? It seems entirely arbirary to me, and smells of an argument that somehow this has made the end goal significantly more attainable.

>why this somewhat arbitrary line being crossed is something I should care about.

That is something personal and unique to each individual. In 1903 when the Wright brothers flew a heavier-than-air machine for 59 seconds, 99.99999% of the people on the planet wouldn't have cared. The airplanes you've flown on are vastly far removed from that original one. Same story for the point contact transistor in 1947. None of that solid state physics is used for modern transistors. Some people like to be early adopters for new ideas and things. Some don't. And that is OK.

Because until now contained ignition has never produced anything meaningful. We've had failed experiment after failed experiment. Now we finally have an experiment with a meaningful more amount of energy out than in.

Is this the right approach? Who knows. There are many fusion designs in the works, and those may ultimately be the right call. Or some yet-to-be-created design. That's even probable. The NIF is for simulating nuclear weapons, not creating energy. None of that takes away from this breakthrough - we've never had meaningfully more output than input on a repeatable basis. It's proof that contained fusion for energy isn't just hypothetical, which will also mean funding & interest will generally increase from this point on.

I think you're setting too high a bar. It's like saying no milestone should be celebrated until we have a working metropolitan-size plant running that's cheaper than anything else. Punch cards in the 1950s are insignificant compared to modern SSDs, yet they were an important step even though we don't use anything like it now. Breakthroughs are breakthroughs.

>It seems entirely arbitrary to me

I agree that the original press release flubbed the explanation. Here's how I think they should have presented it instead:

https://news.ycombinator.com/item?id=33971377#33977940

> It's big because the people doing it call it big.

How does "[It's big b]ecause sustainable positive energy out has never been achieved before in 60 years of research" translate to "because we say it's big" in your head?

You might not consider it big, but a specific reason was provided and it had zero similarity to your rephrasing.

While I'm sure that you're correct, the obstacles are large and there is a lot of overcome still, I can't help but think of James Watt & (my ancestor) Richard Trevithick - the inventor/pioneer of the compact steam engine.

Watt went around telling everyone that Trevithick and his compact (ie high pressure) steam engines were too dangerous and would never work.

Yes, some exploded. But then we got steam trains and even today almost all power generation on the planet is high pressure steam-electric power plants.

> A large, complex machine that explodes the equivalent of 500 lb. bombs to generate heat to drive a turbine sounds like an engineering nightmare.

And using actual bombs and explosives to dig kilometers down and mine coal is not an engineering nightmare? Dying of gas in the mines, fires on oil wells, oil spills, these things are 'engineering simple'?

We don't place precision optics in those blast zones. We don't put structures there that are repeatedly exposed to blast. Over the life of a inertial DT fusion reactor there will be about a BILLION such explosions in the reactor core.

I wonder how much energy each stroke in the largest diesel ship engines has when compared to the energy released by individual bombs/high explosives.

An answer matched in tenor and tone to the question, but nonetheless entirely serious,

is that because while the obstacles are grave, the consequences of failing to overcome them are much graver still,

and to the best of our collective knowledge,

industrial scale fusion would be the least bad answer to our energy demands for the next epoch.

That is true but also does not obviate the need for other parallel efforts and other technologies whose challenges are also very grave, e.g. the need for very near term very large scale carbon sequestration, for a modern electrical grid with deep redundancy and resilience, the need for effective safe scalable stores for energy from whatever source, etc.

> the consequences of failing to overcome them are much graver still,

Why is that? Fusion is not needed, although if it turned out to be cheap that would be nice.