I asked 'In what way does hard solipsism have to 'address elements of fundamental physics'? - perhaps you could address what was asked?
Which was a derail, but nonetheless here is my response.
As far as I am aware solipsism is the notion that we cannot be sure that anything exists except the mind (and presumably the brain, but that second point isn't really necessary).
So let's take as a starting point that the laws of physics as we understand them remain - then this argument needs to address them. Specifically if the mind exists, what sustains the mind. As this would be an energy-using process where does that energy come from. If the mind is the only thing that exists, it would itself need to be energetically self sustaining - an energetic closed system so to speak. But that makes no sense on the basis that if certain processes in that mind are 'energy consuming' then others must be energy generating at the same rate. Either those second set of processes are part of 'the mind' in which case we should know they exist (solipsism is about the mind and the mind alone existing), so what are they. If they are outside the mind then we have incontrovertible evidence of existence outside of the mind.
If we take it in a slightly softer manner - i.e. we accept the brain - then how is the brain sustained without some level of external input - oxygen, nutrients etc.
So solipsism needs to address these fundamental elements of physics.
Alternatively we could posit that in this alternative reality there are different laws of physics - but this simply begs the questions.
What are those laws of physics
Do we have any evidence to support their existence and critically
How do these laws of physics sustain the processes of the mind without there being anything outside of the mind.