These new submarines don't just represent the country's biggest defence undertaking ever - they are strategically critical and hugely technically challenging. And that's the huge danger. It's an endeavour that is - at some point in the huge development cycle - almost inevitably destined to go badly, seriously, and possibly even disastrously off the rails. This is simply a reality embedded in the concept: the idea of creating something invisible.

Building a submarine is regularly compared to developing a space program. This considerably underestimates the myriad difficulties involved.

A space shuttle simply has to transit a uniquely hostile environment at great speed and return, safely, to Earth. While this is, admittedly, difficult, it's nothing compared to a submarine surrounded constantly with water which is actively attempting to crush the hull while evading an opponent seeking to destroy it with independent, remote-controlled torpedoes. The sub needs to travel enormous distances (at speed yet silently); it needs to be large enough to carry missiles (yet completely undetectable); and, crucially, it needs to have uninterrupted communications (yet full awareness of everything going on outside its hull).

And that's why this $90 billion project is so critical for Australia's entire future defence. Submarines are meant to complicate the calculations of any potential opponent.

Armed with cruise missiles, they'd provide a latent capacity to hit back at an enemy's homeland. They are, necessarily, much more than a defensive weapon system designed to simply prevent an invasion. If it was their only purpose, spending that much money on a dozen subs wouldn't make any sense. Technological breakthroughs in precision strike, range and the conventional explosive power of missiles deliver these weapons remarkable strategic power. The problem is that it's exactly these scientific advances that are creating new vulnerabilities for the submarines.

Perhaps the most significant issue is that the submarine is being designed today, using 2020's technology, for a world of the future. This is where the most critical issues, the ones that bedevil the very existence of the project, reside.

It's understandable that the key details of the new submarines are enveloped in secrecy. It's also completely unacceptable that the taxpayer is being asked to hand over billions today for equipment that will almost certainly be obsolete tomorrow.

That's why this conference is so important. Without it we just won't know if there is a real plan to evade these problems in the future.