The point is to get some of it from somewhere cheaper/free - mass, or outside air as in heat pumps.
You can't run your laser on mass or air, if you need a coal firing power plant to run your fusion reactor, from which you get less than you consumed from the coal plant...
It's great progress, it's just not as close to viable as it might sound like - more breakthroughs needed.
I have yet to find someone saying it sounds like fusion power reactors are right around the corner, but I have found lots of people shadowboxing these people and attacking the scientists for misleading press releases.
Seems like an overcorrection to something I haven't even seen anyone here say.
I think to a lot of the technically minded, but non nuclear physicists here, it initially sounded like less (paid for/electricity) energy was used than was put out. That's extremely exciting, and the actual news is still fantastic, it's just that 'actually, we needed to pay for over 100x more energy than we counted as the "input" energy [and it's possible to do 10x but not 100x better than that]' is quite a massive caveat on a 3:2 or whatever yield.
I'm not saying they've claimed anything wrong or deliberately misleading, it's just a misunderstanding/misalignment and possibly made worse by the PR teams in the middle.
In other words, I don't think it's an angry 'well actually' type correction so much as it is disappointment - it initially sounded even greater.
Not necessarily, it depends on how the reaction scales. If the reaction does not scale linearly (as is claimed) you don’t necessarily have to get more efficient, you just have to up the power until the output curve has increased past the input scaling. How big that is is determined by the efficiency of the input device itself, but it isn’t a question of if it will ever happen.
Yes, sure, it's just still a breakthrough or so (or at least work, I don't know how within grasp it is) away from what one may have (as did I) initially assumed.
Tangentially, it does seem fairly intuitive that it should be non-linear in that 'jump start' as it were: a fire can be grown arbitrarily large having started from a single match (or flint or whatever).
You can't run your laser on mass or air, if you need a coal firing power plant to run your fusion reactor, from which you get less than you consumed from the coal plant...
It's great progress, it's just not as close to viable as it might sound like - more breakthroughs needed.