Your probably familiar with the solarsail tech when people use light to push space ships with sails. This is light that is pushing matter with mass, I learned in school that in order to have momentum you have to have mass and light has no mass and therefor no momentum. And if you get hit with no momentum you wont get pushed. So how can solarsails be ''pushed'' by light? And also when I shine a light on paper and it heats the paper(gives it momentum?) does it loose energy and change wavelength?