In this thread about Kerbal Space Program 2 authors says they are building gameplay based on technologies that are potentially viable in the near, or ar future. Main topic there is metallic hydrogen.
It ignited a heated discussion on that technology and some people claim it was already debunked and proven impossible. People there cite various sources that says yes or no for this possibility.
So, what do we know now? For real? Is it already proven impossible? Harder than we thought? Is anyone still working on fuel applications?
What I'm looking for is short impartial overview of the current (beginning of 2020) state of knowledge.
About 3 years ago we had a list of questions on that topic, but supposedly more recent research brings some sad news.
- Would (theoretically) metastable solid metallic hydrogen even need an oxidizer?
- Has (theoretically) metastable metallic hydrogen been considered for use as a propellant?
- For the recently reported production (January 2017) of metallic hydrogen in the laboratory - what is the evidence exactly?
- Are there published predictions that hydrogen could remain metallic at ambient pressure?
- Would a transition from liquid metal to solid metal hydrogen exhibit thermodynamic characteristics of freezing?
Also, new answers to first two would not help us now because we know it was considered and it's not going to change, and oxidizer one assumes it exists and works, and that assumption is what I want to verify.