why is it that when we shine a bright light under our finger we can see the light through it and sometimes even veins but we can’t see the bone?

Question

I’m just confused why we can see tiny veins sometimes but not silhouette of a dense chunky finger bone ?

In: Biology

Answer 1

Light diffusion in the flesh is the simple answer. Diffusion is the ‘spreading outwards’ or ‘spreading something more widely’. Essentially your skin/flesh diffuses the light to make is spread out from the focal point that it enters your skin. You can see veins that are close to the surface and block the diffused light from exiting, but the bone is deeper in the finger compared to the veins you can see (though I’m not aware of being able to see veins in your fingers with light) so the light diffuses around the bone effectively making it invisible to you.

A great visual for this would be a wide spray of water. If you are at the other end of the spray behind a plate of glass you’d see the water. Now put a stick near the glass and you can see it, move it further into the spray of water and it disappears because the water diffuses back around it instead of being blocked by it.

Answer 2

Light diffusion in the flesh is the simple answer. Diffusion is the ‘spreading outwards’ or ‘spreading something more widely’. Essentially your skin/flesh diffuses the light to make is spread out from the focal point that it enters your skin. You can see veins that are close to the surface and block the diffused light from exiting, but the bone is deeper in the finger compared to the veins you can see (though I’m not aware of being able to see veins in your fingers with light) so the light diffuses around the bone effectively making it invisible to you.