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    $\begingroup$ I believe you're assuming 100% absorptance? As the other answer's comment points out, if photons are reflected, you get twice the momentum transfer. $\endgroup$
    – Carl Witthoft
    Commented Jan 11, 2022 at 17:35
  • $\begingroup$ @JonCuster You must also consider the pressure of the outgoing infrared that results from the sunlight heating the field. So, the actual pressure will be intermediate between the perfect absorber and specular reflector cases. $\endgroup$
    – John Doty
    Commented Jan 11, 2022 at 23:02
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    $\begingroup$ I’ve purged a debate about introductory relativity. Please do that somewhere else. $\endgroup$
    – rob ♦
    Commented Jan 12, 2022 at 3:54
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    $\begingroup$ Some additional comments removed. If anyone has concerns about “censorship,” please raise them on Physics Meta, not here. $\endgroup$
    – rob ♦
    Commented Jan 12, 2022 at 14:52
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    $\begingroup$ @samerivertwice your suggested defect is incorrect. For any object $m^2 c^2 = E^2/c^2 - p^2$ which, for a massless object like a photon this reduces to $p=E/c$. Gravity is not relevant to the momentum. A photon has momentum because it is massless and it has energy. The momentum of light is well founded both in theory and in experiment. Here is a lecture that covers both the theory and some experiments: ocw.mit.edu/courses/electrical-engineering-and-computer-science/… $\endgroup$
    – Dale
    Commented Jan 14, 2022 at 13:54