Polywell's current patent application.

[MSimon]

Please show me a public domain invention that ever went anywhere

Three phase electrical power systems - once the patents ran out.

You wouldn't believe the electrical system mess that obtained until the patents ran out.

Same for Watt and the steam engine patents.

I'm quite aware of how Tesla and Westinghouse faced off against Edison. The mess wasnt from the patents, it was from Edison refusing to bow to the inevitable and using his power to lie and manipulate and slander his competition.

Fulton boldly stole Morey's work.

There were two phase systems, single phase systems, and other AC junk that was used until the Tesla patents ran out.

[Lensman]

I don't see that anyone in this discussion has mentioned that the USPTO (U.S. Patent Office) recently revised its process to make it more difficult to obtain a patent. You now have to demonstrate your invention or discovery is "non-obvious"; that it's not just a trivial variation on what others have patented.

So it's possible the patent app was abandoned because the team wants to write a new patent application using a different strategy, to deal with the new criteria from the USPTO.

Remember guys, the WB-8 contract explicitly asks for a WB-9 design.

The vagaries of patent law being what they are, this doesn't seem worth worrying a lot about. It might just be that Bussard's death invalidates the petition, or someone at EMC2 forgot to keep it going, they don't care, they're going to patent the WB-9 design instead, or who knows what.

It's silly to think they are abandoning Polywell in the middle of the WB-8 contract based on this.

Yup. There are several possibilities here, including-- as you say-- that they may simply have decided to pursue a patent based on a later design.

[Lensman]

Please show me a public domain invention that ever went anywhere...

Well, I see you've already gotten some good replies to this. But more generally, anything invented more than 20 years ago. This includes common fasteners such as screws, bolts, nuts, etc. You will notice that companies are still making such fasteners.

More to the point, you will also note that people are still building coal-fired power plants, altho all the patents on the steam engine ran out centuries ago.

Now, you do have a point that VCs are going to be leery of a cutting-edge tech startup that has no patent protection. But there are exceptions to that rule, and this is certainly one of them.

The long sought-after "holy grail" of commercial fusion power isn't going to languish just because one or several patents ran out. In fact, I'd argue precisely the opposite; a lack of patent protection would mean anyone can build one, so if the Polywell proves practical, likely there will be a boom industry in building them.

[MSimon]

It is also possible that the US Navy has declared the patents secret. It has happened before.