# Tag Info

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Your question is not specific to inflation, and really applies to any case where a bosonic quantum field behaves semiclassically due to macroscopically large occupation numbers. One very simple example of this is the Stark effect in quantum mechanics, where a Hyrodgen atom is placed in a uniform electric field. The atom is treated as a quantum mechanical ...

3

Diffeomorphism Invariance Let $M$ be a smooth manifold. Let $\phi: M \to M$ be a diffeomorphism. A simple property of the Einstein equations is $$g \in \otimes^2 TM \text{ is solution to vacuum Einstein equation} \implies \text{ so is } \phi^*g$$ To see that this is true, simply pull back both sides of the Einstein equation by $\phi$, and use the ...

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I would look at this in a slightly different way. Rearranging it: $$m \ddot{x} = -(a|\dot{x}|+k) x = -k_{eff} x$$ If you look at it that way, it is really a variable, non-linear stiffness $k_{eff}$ that depends on the velocity, rather than a damping that depends on the position. In this respect (assuming $a > 0$), the stiffness coefficient has a lower ...

1

This is an every day term, with no meaning for physics. In the Oxford dictionary for "energy" one gets: Physics The property of matter and radiation which is manifest as a capacity to perform work (such as causing motion or the interaction of molecules) In science fiction one might separate zero mass particles, like the photon and the graviton ( ...

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when a signal is analyzed in time domain they are called spectrum or you can say that signal is in spectral domain. but when the signal is analyzed in frequency domain and amplitude of such signal is taken to analyzed the signal then they are said to be in cepstral domain.

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International Handbook of Research in History, Philosophy and Science Teaching quotes the English translation of Guisasola et al. (2008), which discusses some of the early history of the EMF. The man who coined the term "electromotive force" was Alessandro Volta, who stated that there was a force separating the charges in current flowing in a closed circuit. ...

1

Gravity is the physical phenomena by which bodies attract themselves. It is the effect we observe. Gravitation is a model, a theory to explain the observed phenomena. The Newtonian Gravitation explains this phenomena in terms of attractive forces generated by massive bodies. It dos not depend whether the bodies are terrestrial or celestial. General ...

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The adjoint of an operator is obtained by taking the complex conjugate of the operator followed by transposing it. i.e., $(A)^\dagger_{ij}=\left((A)^T_{ij}\right)^*=\left((A_{ij})^*\right)^T=A_{ji}^*$ You can do it in any order. The adjoint of an operator is the infinite dimensional generalization of conjugate transpose, where you find the transpose of ...

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They both refer to the same thing. The habitable zone is also called the Goldilocks zone, a metaphor of the children's fairy tale of Goldilocks and the Three Bears, in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is ...

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The meaning you quote is only one of several. From the same dictionary, others which are now obsolete or not often used are 3: importance in influence or effect 4 obsolete : a cause or motive of action and it is from these that the scientific meanings derive : 6a : tendency or measure of tendency to produce motion especially about a ...

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