I found the following picture in the Internet and I am curious how from a physicist point of view to explain it. Basically the idea is the following. If you are a normal person - you suppose to see Einstein here, but if you are myopic, then you will see Marilyn Monroe. If you will move far awa...

This is a part answer in regards to the weighting factors: According to the Smithsonian Environmental Research Centre's page "How is the UV-Index Calculated?", the weighing factor are not so much made up, but is weighted according to how human skin responds to each wavelength; it is more imp...

I have a thought that this question is off-topic. But... From the day I joined here, I was active (though I had low-quality answers, I was still actively answering) for almost 8 months. Then, I had a vacation (can't use internet that much) when I stopped answering. I (am) still visited (visiting...

After performing a Lorentz transformation, the orthogonal coordinates will become skew, as in the following figure: and in such coordinate system, according to this Wikipedia article, the metric will have off-diagonal non-zero elements: $$g_{ij}=\mathbf{e}_i.\mathbf{e}_j$$ which is not that o...

Some basic Physics books are often misguinding in the sense that they don't make clear whether something is a primitive concept, a law, a definition or a theorem. This is often a little confusing. I've asked here some moments ago if there's a definition of force, and I've been redirected to a que...