# What would be more effective for a Shkadov thruster? An entirely white one or a mirror one? [closed]

A Shkadov thruster is a megastructure which reflects all light from a star in a given direction.

What reflects more radiation, a white or a mirrored surface?

## closed as off-topic by sphennings, Vylix, L.Dutch♦, MichaelK, SecespitusOct 19 '17 at 7:23

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question does not appear to be about worldbuilding, within the scope defined in the help center." – sphennings, Vylix, L.Dutch, MichaelK, Secespitus
If this question can be reworded to fit the rules in the help center, please edit the question.

• You're effectively asking "What is more reflective; a white surface, or a mirrored one?" Besides the fact that for visible light the answer is quite obvious, as written this question has little to do with worldbuilding besides the fantastic nature of a Shkadov thruster. – sphennings Oct 19 '17 at 4:22
• I guess space or physics stack exchange might be a better place to ask, as this is quite well established theory, and what you need is sound physics rather than creativity. It might be on topic here, but still. – Mołot Oct 19 '17 at 5:16
• "White" and "mirrored" are qualities that only applies to visible light. So what qualities the surface has towards all other forms of radiation is unknown, since you have not specified that. Hence the question is unanswerable. If is kind of like saying "At my zoo, how well does it work for the birds, dolphins, otters and tigers if my bear pens are fences or plexi-glass; which is best?" – MichaelK Oct 19 '17 at 7:12

• @Vashu: When a photon collides with a stationary body, and is completely reflected from it, then the body receives an impulse p = 2hf/c, where f is the frequency of the photon. the body should then be moving with a speed of v = p/m, which in this case is v = 2hf/mc sciforums.com/threads/impulse-of-a-photon.43433 – nzaman Oct 28 '17 at 16:35