10 questions linked to/from Physics the Why vs. How question?
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### Why do same/opposite electric charges repel/attract each other, respectively?

I know plus pushes another plus away, but why, really, do they do that? On the other hand, molecules of the same type are attracted to each other. I find that weird. I do know some stuff about four ...
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### Will we ever be able to view the past?

By analogy with the sun, whose light is apparently reaching us in 8 minutes, it means that we are only viewing the sun 8 minutes ago when we look up at it. However, what if we were eventually able to ...
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### Surely space-time Curvature does not explain gravity, it just describe its effects?

In special relativity co-moving objects see the other's 4-velocity as being only temporal. When they move relative to each other they see the other's 4-velocity has rotated so that it points less in ...
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### Why does light travel as waves? [duplicate]

Why does light travel as waves instead of say just a straight line? What are the forces that make a light photon travel in a wavelike pattern?
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### Why does light travel at finite speed? [duplicate]

We have known for quite some time now that light travels at a finite speed of 3x10^8m/s (approx) through vacuum. But why is that? Why can't the speed be infinite? Or at least higher than the current ...
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### Why are D'Alembert's Principle and the Principle of Least Action Related?

Why do we get the same differential equations from both principles? Surely there is a fundamental connection between them? When written out, the two seem to have nothing in common. \sum _i ( \...
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### Where does the energy within atoms come from?

Most kinds of energy I know about involve a finite measurement and are transferred. In other words, energy in the universe is finite and is not lost or gained but only transferred through space one ...
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### A magnets north pole and south pole

Why does the N pole of a magnet do not attract with the same pole but the N pole of a magnet attracts with S pole?
The term "coupling" between quantum fields refers to certain terms in the Lagrangian (density) $\mathcal{L}$ where the respective field operators appear together, e.g. $g\phi^\dagger\psi$ with ...