Do you mean this: https://en.wikipedia.org/wiki/Solar_sail ?
the question is whether a vehicle can approach the speed of light ;-)
It is possible to realise a force on an object by reflecting electromagnetic radiation from it. Most likely use is in spaceflight. The acceleration likely to be realised is very small. Relativistic effects preclude the object from getting to light speed.
why would you like to go for extremely long wavelength?there is more chance to get some effect with rather short wavelength..there were some discussions to "Push away"incoming asteroids with strong laser beams (radiation pressure)
Better to use a short wavelength because it is easier to steer it and to generate a narrow beam, and if it is radiation pressure that it uses, then if the beam is reflected backwards, rather than scattered randomly, the force is doubled. If the wavelength is much larger than the object then it will be scattered over a wide angle. If the wavelength is similar to the surface roughness it will also be widely scattered, so there is a range of wavelengths that can give most efficient propulsion.
I believe, the author means not the wavelength of traveling wave in common sense, but the transverse field distribution parameter, where for plane wave it is really infinite. now guess, we have some high power source of spherical wave, like a hydrogen bomb in space... can we surf its wave front or not?
It might be possible using a moving charge (at right angles to the magnetic field and to the direction of the wave) with a direction of motion synchronised to the rate at which the waves were going past, so that the force on the moving charge due to the magnetic field was always in the direction of motion of the wave. Not sure if all the work needed would come from the effort needed to keep the charge moving, or whether some or most of it would come from the wave, which is what is needed if the comparison with surfing is to be valid. A long wavelength (low frequency) would mean mechanical means of moving the charge would be possible.
The frequency at which the charge needs to change direction would fall as the object moved faster.
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