: Straightening the wave would lengthen the wavelength but would also lower the frequency. So a longer wavelength at a lower frequency would still have the same speed. Besides, since photons have zero mass, how could they be directly used for travel? It is not possible to "ride" a light wave because it has no inertia to push us with.

light does have inertia and the ability to move things. Sattelites in orbit have had their courses alterred by thousands of kilometers by the suns light. these satellites aren't riding the waves, rather they are being buffeted by them.