I'm happy to hear someone make this point. Rather than sneering "vaporware" when decades fail to crack a problem, I would prefer us to keep in mind that if we never try multi-generational projects, we will never taste the fruit of multi-generational projects, and those are some sweet fruit indeed.

It's also good to have a number of these things in the oven, because it's hard to predict when a sudden discontinuous leap might make practical in the short term something that previously seemed like a multi-generational project.

I presume almost no one in 1920 could have imagined that anything approaching the output of fission energy would become common in their lifetime.

It runs into the spaceship problem where later iterations of a spaceship reach the destination first because new technology allows them to fly faster. At some point (maybe) materials and other technology will develop enough so that fusion becomes feasible on a decades or so timeline. Or solar & battery technology will develop to the point where fusion isn't really needed.

But if the first spaceship was never developed, would the second spaceship have been?

Sure because you develop technology while working on achievable goals. As an example, what could someone in 1920 do to help develop fusion power? Pretty much nothing that would be practically useful today. But they had stuff they could achieve which laid the groundwork to what we're doing today.

But then you run into things that you only discover while trying to do something practical. Like the space shuttle having to land--NASA developed grooved runways specifically for this purpose and now they're on our highways. https://www.nasa.gov/centers/langley/news/factsheets/Groove....

There are technologies, materials, and methods we've developed, tested, and perfected because of some specific need. I mean, how much of the internet do we have today as a result of CERN having to store and share vast amounts of data and information?

Sure, you can say /eventually/ we would've come up with alternatives. But a lot of the internet and technology in the 90s came as a direct result of CERN doing practical things. How would we know we'd need solid state drives today if we didn't develop a need for hard drives? The same can be said of NASA, the space shuttle, the Hubble telescope, etc.

Going back to CERN, maybe it would've been better to wait for the Superconducting Super Collider because it was going to be more powerful than the Large Hadron Collider. But so far only one of these particle accelerators has detected the Higgs boson.

Your examples agree with what I am saying. Target things you can build today.

I was just talking about this the other day, its formal name is called the Wait Calculation https://en.wikipedia.org/wiki/Interstellar_travel#Wait_calcu...

How does it make any sense for science? If noone builds version 1, there will be no version 2.

You can't skip inventing ironworks because eventually titanium will be invented.

It's an interesting sci-fi thought, but why wouldn't the second spaceship just catch up with the first one and pick up the passengers to avoid their unnecessary travel time?

Why pick up the passengers only? Plan ahead and build it to pick up the entire ship, including not just the passengers but all the materials and supplies they had packed as well.

Incompatible docking apparatus, not backwards compatible. Engineers invented these doors, after all.

So? If you know there's another spaceship that you're going to pass and you need to pick people up, you make your docking apparatus backwards compatible.

This isn't rocket science :-)

Yes but this spaceship was made by Apple. It's a feature.

Because you'd have to leave the 2nd one nearly empty to fit the extra passengers in?

Might be a good idea if nobody wants to go on the 2nd ship though.

I am not sure if we have a project that spans multiple generations?

It would be easier to do a project that provide some kind of immediate benefit while having long term multigenerational long term effect.

Science is kinda that way. We get immediate knowledge with long term unknown payoff.

Not a scientific achievement, but doesn't the Sagrada Família count?

"On 19 March 1882, construction of the Sagrada Família began ... It was anticipated that the building would be completed by 2026, the centenary of Gaudí's death, but this has now been delayed due to the COVID-19 pandemic."

Continuing construction (admittedly not continuosly) for roughly 150 years is pretty impressive in my opinion.

https://en.wikipedia.org/wiki/Sagrada_Fam%C3%ADlia

The Netherlands would like a word. Holding back the sea was a monumental project that will definitely last generations to come. Maybe not as exiting as high temp superconductors and fusion but still a nationwide unique product.

It may last for generations to come, but did the original development take generations?

Old-school land reclamation worked by putting woven fences in the water where waves would deposit sand over decades and centuries, slowly growing the land bit by bit. Those versions were already multi-generational projects.

(I'm citing the techniques used in the north frisian wadden sea, I'm unsure if the same techniques were used in west frisia as well)

Oh, that's very interesting. So I'm guessing that technique was used to make areas that were put of the water during low tide, and then eventually dikes were added to make them dry land?

Exactly. But this technique only allows you to get land that's exactly at sea level, so dikes are absolutely necessary.

This also means you need drainage systems to remove the water from already reclaimed land, as it's still exactly at sea level and will be relatively wet marshland otherwise.

Thats why the netherlands built those old school windmills. thats how land was reclaimed below sea level. They no longer serve the same function but are used instead for small shops and for tourists.

Many churches built before the industrial age took multiple generations to build.

Modern civilisation may not have multiple generations left.

And it might not even take an all out nuclear war, social media may turn out to have been even more destructive than nukes.

Also in the era of family businesses, businesses were much more sustainable, sometimes competitive over hundreds of years. The useful lifespan of a modern public company is much smaller.

Decommissioning a fission power plant and storing nuclear waste in a safe way? That's probably a multi civilization project. The easy part first.

that's perfect analogy, since most fruit & nuts are multi-generational projects.

> we, as a culture, have a problem seeing and planning across generations

From a political perspective, there is little incentive to plan further ahead than the current administration.

Yup, that's exactly the problem. We need to find an incentive for the ones in power to invest in things that would be good for the future.

Maybe I'm going too far but in the future cryonics and being frozen and be brought back when the promise of these investments be resolved in the future might create some incentives.

Even though this seems super-scifi for now, it probably won't be in about 100 years.

Yes! As a concrete example, people spent all of the C19 trying to fly, learning lots about aerodynamics along the way (https://en.wikipedia.org/wiki/History_of_aviation#19th_centu...). This culminated in the Wright Brothers making the final improvements that made it work. A century or two to get fusion would be quite efficient.

We're currently on course for having trouble existing across generations. The path we're on now I don't think meeting fusion goals will be big concern if there's anyone around to even be concerned.

True, but if we can crack fusion energy, we can stop burning fossil fuels and we might even have ample energy to extract CO2 from the atmosphere.

We already have the capability to economically capture atmospheric carbon with existing nuclear power generation systems

<poignant joke about being able to capture atmospheric carbon since the dawn of time>

Fusion produces a lot more radiation than fission, AIUI.

What makes you think it will be any more politically viable to scale out than fission reactors?

> What makes you think it will be any more politically viable to scale out than fission reactors?

IIRC a major difference would be the danger potential in case of a "meltdown", since a fusion reactor wouldn't have kilograms or even tons of uranium etc. laying around to form another elephant's foot but "just" the irradiated reactor vessel which AIUI is both not as dangerous or as long-lived as fission fuel, a fission reactor itself and fission waste products.

Also IIRC the actual "meltdown" of a fusion reactor would involve the reaction environment (extremely high temperatures and pressures) breaking down at which point the reaction stops almost immediately no longer producing any additional radiation or waste products, leaving only the already irradiated reactor vessel to deal with since the comparatively tiny volume of reactant(s) (probably one or more different Hydrogen isotopes) and reaction product(s) (probably Helium) will escape quickly and with pretty much no harm done.

That is a sane, logical argument.

I'm just worried. If sane, logical arguments worked, then there'd be a lot more fission reactors in the world and a lot fewer coal plants.

Yeah; meltdown-proof clean fission reactors have been a solved problem for what, fifty years now?

There is no nuclear waste, what radiation are you measuring to come to this conclusion? neutrons that dissapear the moment the reactor switches off?

Activation of the reactor walls. The neutrons don't disappear; they're absorbed, and some fraction of the atoms that absorb them become radioactive themselves. I've seen lifetime estimates ranging from five to ten years for the walls, after which they'll be high-level waste.

Isn't the breeding blanket suppose to prevent that?

The breeding blanket does slow the neutrons, but there needs to be a first wall material that does not ablate into the plasma. You need very little of non-hydrogen material in the vacuum to cause a density collapse. If you made the wall out of liquid lithium then there would be a lot of lithium in the plasma.

Tungsten is a good choice for a first wall material because of its uniquely high melting point, low rate of embrittlement in high neutron flux, and short-lived radioisotopes.

Would it? We could have hundreds of runaway-meltdown proof nuclear fission reactors now if we wanted.