While fire itself may not have mass or density, the materials involved in the fire (fuel and oxygen) do have density.
In the context of a rocket engine, the combustion process involves the ejection of high-speed exhaust gases, which have mass and therefore contribute to the overall density of the vehicle.
We’re in agreement on the physics of rocket propulsion. However, “fire” is essentially defined as a chemical oxidation reaction. The reaction itself doesn’t have mass. While fuel and oxidizer undergo the oxidation reaction, it isn’t the reaction itself providing the propulsion, its the mass and velocity of the combustion products.
This is why the “natural element” definition is old and out-of-date. Any discussion of “fire” as an element is a philosophical or literary exercise, not a scientific one.
While fire itself may not have mass or density, the materials involved in the fire (fuel and oxygen) do have density.
In the context of a rocket engine, the combustion process involves the ejection of high-speed exhaust gases, which have mass and therefore contribute to the overall density of the vehicle.
We’re in agreement on the physics of rocket propulsion. However, “fire” is essentially defined as a chemical oxidation reaction. The reaction itself doesn’t have mass. While fuel and oxidizer undergo the oxidation reaction, it isn’t the reaction itself providing the propulsion, its the mass and velocity of the combustion products.
This is why the “natural element” definition is old and out-of-date. Any discussion of “fire” as an element is a philosophical or literary exercise, not a scientific one.
I think you nailed it - fire is not analogous to earth, wind, and water (and heart), so the premise of the post is confounded.
I tried to imagine a vehicle for travelling on a surface of Heart, then decided I don’t want to.