Hacker News Reader

Comment by gigel82 | Hacker News Reader

The top reply to the top comment on that thread is a caution not to get overexcited. The second is a question. The third is another caution.

Almost everyone in the top of any given subthread is approaching it very realistically.

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

The top commment though is just wrong. He says Q would be 0.375 with modern lasers. Which would be worse than the result announced today! Q is a factor internal to the fusion reaction, so upgrading to more efficent lasers would not change Q.

Presumably he means something like total energy efficency would be very close to breakeven with modern lasers. You can tell how dubious this is from the fact no one involved in the project says anything like this. In fact, breakeven is still two orders of magnitude away and I don't believe anyone has suggested anything more optimistic.

It (combined with the ignition last year, which this shows wasn’t a fluke) definitely WAS a “leap of some kind.” Showing fusion ignition shows potential scalability, and this is confirmed by the achievement of scientific breakeven.

If you scale up a process that only returns 1% of the energy you put in (which is the case here based on how inefficient the laser is), you’re still not gonna come out ahead.

The scaling is non-linear, which is exactly why ignition is important. By showing that fusion heat is actually leading to more fusion reactions, to get double the amount of energy out of each shot, they won't have to double the amount of laser light. In other words, higher gain should be relatively straightforward scaling of the system.

(Also, the laser inefficiency is a complete red herring as they just used plain old flash lamp pumped lasers, not the much more efficient lasers we could have used and which are available now, with efficiencies about 10-20 times that of those used.)

They achieved a 1.5x gain. To get useful electricity out (without heroic efforts) will require a gain of 20-50.

1% or did you mean to say 101% -- they demonstrated a net gain didn't they?

As I understand it they demonstrated a net gain relative to the energy output by the laser, but not relative to the energy put into the laser. 1% is correct for the actual efficiency given the cost to generate the laser.

(Yes, that distinction does seem important and wasn't brought out by the news reports.)

These are the people desperate for hope, not truth. When they’ve seen many such “breakthroughs” over the years that ultimately lead to nothing, they will learn to look upon such announcements with a cynical heart. You could tell me the cure for cancer was discovered tomorrow, and I would immediately search for reasons why it’s bullshit.

Reply on news.ycombinator.com