You misunderstood.

You are thinking about dust-in-dirt passing physics. That is NOT the entire process. That's the very end of the process.

Maybe you are not familiar with this use of the phrase?

Elon Musk uses the “it must pass physics” phrase to basically mean that the ENTIRE THING has to obey the laws of nature, not just the last step.

Perhaps this example can clarify the concept:

Using electrolysis to extract hydrogen from water is, to use your phrase "a known quantity and doesn't need to be repeated for every new study in the field". In other words, that process is real and "passes physics".

If, on the other hand, we propose to use electrolysis to generate liquid hydrogen to use as fuel, the ENTIRE PROCESS has to pass physics.

It does not.

Why?

Well, it takes approximately 55 kWh of electrical energy to extract 1 kg of gaseous hydrogen from water.

Great.

However, 1 kg of gaseous hydrogen contains 40 kWh of energy.

In other words, you have to use MORE energy to extract the hydrogen than the energy it contains. This idea, at the most basic level, does not pass the physics test. It's a fantasy.

Once we add such things as the inefficiencies of generating the energy, energy transportation losses (wires, connections, transformers, etc.), the energy required to bring the water to the electrolysis plant and run it at scale, the energy required to liquify hydrogen (12 kWh per kilogram), the energy required to transport and manage liquid hydrogen, etc. Well. The entire story quickly becomes a ridiculous fantasy. You are going to expend more than 100 to 200 kWh per kg of gas to deliver 40 kWh of stored energy in liquid form.

That's what "does not pass physics" means. The entire process cannot stand up to scrutiny when all factors are considered.

So, all of this, and the steps I have not listed (for example, fuel delivery), have to pass physics as a complete proposal:

- Mine massive far-away lava fields
- Likely use explosives, strip mining and very large machinery
- Burn large amounts of diesel and other fuels
- Generate massive amounts of CO2 through this process
- Cause serious environmental damage
- Transport what you mined
- Burn large amounts of diesel and other fuels
- Generate massive amounts of CO2 through transportation
- Crush it into a fine dust
- Consuming very large amounts of energy
- Generate massive amounts of CO2 through this process
- Transport massive quantities again
- Burn large amounts of diesel and other fuels
- Generate massive amounts of CO2 again
- Likely need for massive amounts of chemicals as part of all of the above
- Use a high carbon footprint process to distribute the dust
- Burn large amounts of diesel and other fuels
- Use a high carbon footprint process to bury the dust to the required depth
- Burn large amounts of diesel and other fuels
- Hope and pray for enough rain
- Hope and pray you don't destroy the fields for agricultural use
- Etc.

What I said is that phase 1 should be about proving that the entire thing passes physics. For that stage, it is OK assume that the proposed final element passes physics (whether we know it or not). What you are trying to quantify is everything else, which, in this case, is everything before a particle of volcanic dust finds itself 30 cm deep in dirt at a farm. That's what you have to prove before the physics of that dust particle in dirt is even remotely relevant in the context of the proposal.