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Comment by DesiLurker | Hacker News Reader

> But that's energy, no electricity as far as fusion viability is concerned net energy (over whats put in) is enough. the whole electricity is moving the goal post because there are plenty of other sources that primarily produce heat.

Now regarding efficiency of laser itself, sure they are inefficient but from just nuclear fusion pov net energy gain is a significant milestone in itself. lasers can get incrementally more efficient, at least there was not incentive to make them super efficient so far & there are no known fundamental problems with making them efficient.

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Lasers can get over 50% efficient (although these are specialized types).

It’s silly to blame a facility not designed for power production for using inefficient lasers.

This is an important and necessary step to getting resources to go further. Imagine how dumb it would’ve been to build a fusion power plant before we could even do 1.2x energy gain. A complete waste of resources.

> the whole electricity is moving the goal post because there are plenty of other sources that primarily produce heat.

There's no industrial processes that make use of plasma in the 10s of megakelvins. It's also not moving the goal post at all, since generating electricity is the literal goal of nuclear fusion. If it's just heat you're after, we've solved that problem over 70 years ago. There's hundreds if not thousands of thermonuclear fusion devices readily available literally at the push of a button. But for some odd reason we try hard not to use them and focus on electricity instead...

The question is whether this is a breakthrough and a significant milestone or not. It seems to me like your comment suggests that we have hit the "significant milestone" marker only when we have an actual electricity-generating fusion reactor, which I think diminishes the actual breakthrough that a positive net energy gain represents (if correct). It was long sought after, it has now been reached.

Exactly! This is a very good question that requires some context, preferably from within the field. What does it actually mean?

Sadly, however, the article doesn't seem interested in answering that question and providing the necessary context. Instead it quotes authors of books, who seem ecstatic about the possibilities.

You'd be correct in calling me a cynic when I say that I've heard the "too cheap to meter"-slogan from back in the 50s when nuclear fission was the future.

But I try hard not to be that guy and genuinely want the same question answered - is this an actual breakthrough and a significant milestone in the big picture? Up to this point it's been hit-and-miss and many so called "breakthroughs" turned out to be small steps in the right direction, but not exactly quantum leaps.

EUV light source generate plasma that is in the megakelvin range today for silicon lithography. It's obviously not the same and still cooler, but the assertion that we don't make use of highly energetic plasma is off.

Secondly, your attempt at being pithy about nuclear bombs is a complete loss. We previously only knew how to achieve an inertial confinement based fusion reaction with a positive Q factor by first setting off a fission bomb, and this was only done for the neutron generation to increase the amount of fissionable material exploded (which is why they are called fission-fusion-fission bombs).

We can now generate fusion energy in a way that is obviously confine-able. That's a major step, and it's not THAT hard to imagine many mechanisms of turning a hot droplet into energy. For example the hohlraum itself in an indirect system will obviously be heated by the reaction and could be used to generate steam. Engineering that makes no sense though if you can't get a high Q factor out of the ignition itself, hence the focus.

This four sentence post is a perfect example of OP's point. No insight, no though process, just a pithy negative reply.

> EUV light source generate plasma that is in the megakelvin range today for silicon lithography.

Only an order of magnitude off, but yeah, physicists and spherical cows and all that.

> Secondly, your attempt at being pithy about nuclear bombs is a complete loss.

A little sense of humour is lost on so many bitter souls these days, it's kind of sad. Lighten up, mate!

> Engineering that makes no sense though if you can't get a high Q factor out of the ignition itself, hence the focus.

You do realise that the fusion reaction we're talking about lasted for less than a trillionth of a second in a miniscule area, while other practical designs are aiming for continuous operation in the half hour range to examine practical engineering challenges of particular reactor configurations?

A high Q-factor may be completely useless if the underlying concept doesn't work for actual power generation and one might be easier to achieve than the other (i.e. getting a continuously working reactor first and tweaking it to improve Qp). The question therefore becomes, what's the actual value of the result. The article doesn't even touch on that, while even some C-grade online publications provided context like that.

> but from just nuclear fusion pov net energy gain is a significant milestone in itself.

Didn't we get to that milestone when they detonated a fusion-based bomb back in 1952?

https://en.wikipedia.org/wiki/Ivy_Mike

Anyway, I'm not sure it's a significant milestone. It's just a number along a scale. If you were to tell me they've achieved a _sustained_ reaction which yields more energy than goes into it, for a period of, say, a day or so - then you could claim a significant milestone has been reached.

And even with that, some people argue that given how there's basically no sustainable source of tritium for large-scale electricity generation, the whole exercise is pointless unless the process uses other combinations of elements.

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