# Tag Info

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At present for physics research, a phenomenologist is a theoretical physicist who is well grounded in the current physical theories and at the same time understands the data and can create detailed theoretical models that can predict the behavior of future experiments. In this context, phenomenology is the study of the way current theories fit the data and ...

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ATLAS has no experiment-wide definition of "fiducial", it basically means sensitive to signal. The definition is confusing because, unlike most experiments, ATLAS (and CMS, D0, CDF, etc) doesn't just define the physical area where the experiment is sensitive, they also define collision properties. This means the definition of fiducial isn't limited to the ...

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If $\text{det } g = 0$, then $\text{ker } g \neq \{\vec{0}\}$, ie there is some vector $X \in \text{ker } g$, such that $g(X,\ast)$ gives zero 1-form, so $g(X,Y)=0$ for any $Y$.

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Can someone explain why the time-independent Schrödinger equation isn't an eom? The TISE is an eigenvalue equation due to applying separation of variables to the TDSE; it is an equation for the spatial function alone. Can someone explain in what sense exactly is the time-dependent Schrödinger equation an equation of motion? A Lagrangian ...

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Technically this question is off topic and would belong in an astronomy SE, but the answers you probably are seeking are terrestrial or terran depending on whether it is a person or an object. Terran has been sorta scooped up by the Starcraft community though so terrestrial is used in almost all cases to my knowledge.

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Suppose we have two Hilbert spaces $\mathcal{H}_A$ and $\mathcal{H}_B$. A quantum state on $\mathcal{H}_A$ is a normalized, positive trace-class operator $\rho\in\mathcal{S}_1(\mathcal{H}_A)$. If $\mathcal{H}_A$ is finite dimensinal (i.e. $\mathbb{C}^n$), then a quantum state is just a positive semi-definite matrix with unit trace on this Hilbert space. ...

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For those curious I was able to find an answer. IT stands for Isomeric Transition. A metastable state emits a photon to decay to a lower energy List of decay modes: http://ie.lbl.gov/education/decmode.html

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This presentation (NB: PDF) has a "jargon" page that states, Fiducial (Webster's): Taken as a standard of reference Founded on faith or trust Having a nature to be trusted Fiducial Volume (Particle Physics): The volume used to make physics measurements The volume where the detector is assumed to be well understood With the ...

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cms and kgs are wrong. The SI units are abbreviations which are also used in the plural. You will write 2.6 m/s or 1 m/s, but say "2.6 meters per second" or "1 meter per second" respectively. Keep in mind the SI units are also used in tons of other languages that do not form the plural by attaching an -s. The units look the same in those languages. (e.g. ...

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A good question, you are right the frequency remains constant (unless you have Doppler effects due to relative movement, but that's not your question). For visible light, refraction properties are quite often in question and as such it make sense to speak in terms of wavelength. As you go even higher in "frequency", physicists start talking in keV and MeV ...

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Let $M$ be your spacetime, a smooth manifold equipped with (pseudo) Riemannian metric (for example $\mathbb{R}^{(1,3)}$ for special relativity). The set of reference frames is the frame bundle over $M$, usually denoted $FM$. Explicitly a frame at point $p$ in $M$ can be viewed as an ordered orthonormal basis (with respect to the the inner product defined ...

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It comes from S matrix theory, long before quarks were imagined, S,T and U characterize the type of exchange in the Feynman diagrams entering the S matrix calculation, and they are called Mandelstam variables. s channel-------------------------- t channel------------------------u channel duality meant that the sums could be done either in S ...

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I think what he's saying is that $$F_{net} = F_{nc} + \nabla U,$$ which is pretty standard. $f^a$ is your net force, which is the sum of your conservative and nonconservative forces. Conservative forces can be written as the gradient of some potential, which is where you get your $\nabla U$ from. $f^e,$ then, are your nonconservative forces.

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When we say something is conserved or that there is a conservation law for a given thing, we mean that the quantity of it does not change. You neither lose nor gain any of that thing. More specifically, conservation can come in two flavours. Something can be globally conserved. This means that the total amount of that something in the universe does not ...

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When you say If something goes outside, then it will decrease inside! what you assume is exactly a conservation law. It may seem trivial, but it is not necessarily. Consider the population of a city, for example. At one point in time, you measure how many people are within the city borders; let's call this number $N_0$. Then, you observe all city ...

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The kinetic term of the Lagrangian is proportional to $$g_{ij}v^iv^j$$ where the $v$s are the generalised velocities. Writing them as the time derivative of the generalised coordinates, i.e. $v^i\dot q^i$, taking the square root, and multiplying by a small time lapse $\epsilon$ you get $$\sqrt{g_{ij}\dot q^i\dot q^j}\epsilon,$$ which is a first order ...

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In some detector experiments, The response at the periphery of the detector is poorly understood. The majority of background events interact in the periphery of the detector. The periphery of the detector is the final shielding. Some parts of the detector may be broken. In such cases, results from such parts of the detector are ignored. The results are ...

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According to page 291 of Brian Cowan's Topics in Statistical Mechanics, a relation of the form $$U=U(S,V,N)$$ is referred to as the "fundamental relation" for the system. That is, internal energy (or more generally, a thermodynamic potential) expressed as a function of entropy $S$, volume $V$, and particle number $N$. Note that a relation of this form ...

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There is no general definition of a body for physics, as in everyday speech where one has to qualify further either by context or content. A body of water, means a bulk ensemble of water molecules and further analysis depends on the context. Two colliding bodies could be billiard balls or asteroids. It is a blanket term that needs further attributes if ...

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In the degenerate interiors of neutron stars, the equation of state is usually just density (and composition) dependent. You can express the pressure as a polytropic law of the form $P \propto \rho^\alpha$, where $\rho$ is the density. A stiff (or hard) equation of state is one where the pressure increases a lot for a given increase in density. Such a ...

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Hadrons are strongly interacting particles, and at the elementary particle level are studied by Quantum Chromodynamics within the standard model. Before the standard model became standard, hadrons were studied experimentally and a multitude of resonances were found in meson meson or meson proton interactions. These were studied theoretically using particle ...

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The proper constructions resembling quantum mechanic's formalism does exist in classical mechanics, but it goes a bit beyond lagrangian formalism. In classical mechanics, you can represent a system by a phase space with points corresponding to states of the system. Now, functions over that phase space form a symplectic Lie algebra together with the Poisson ...

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Of course they both give informations about the motion of bodies. The kinematic equations tell us simply what are the valors of the variables of the specific motion , that because kinematic studies only the variables of the motion and their changing. kinematic equations give us indications about : Velocities (the most simple and known equation of kinematic ...

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1- A degenerate matrix is a matrix whose rank is smaller thank its dimension. 2- A singular (non-invertible) matrix is one who has a vanishing determinant. Equivalence of the two : A matrix whose rank is smaller than it's dimension when diagonalized will have at least one zero eigenvalue, and consequently a vanishing determinant.

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If you are talking about rigid bodies like billiard balls or asteroids one has a definition of a body: In physics, a rigid body is an idealization of a solid body in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it.(Wikipedia) ...

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I think Terran is as good a word as any, as is Geo. Thinking of terms where Solar or Lunar are used. Solar Gravity, Lunar Gravity, Terran Gravity, or Earth's Gravity. Solar Magnetic Field, Lunar Magnetic Field (which, I'm not sure there is one), Earth's Magnetic Field or Geo-Magnetic Field is also used. Earth's, Geo or Terran are the best 3 options I ...

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I believe you have the basic ideas correct. The binding energy is the energy required to create Z separate protons and N=A-Z separate neutrons from a (A,Z) nucleus in its ground state. Another way to think about it is binding energy is the mass energy which is missing from a nucleus compared to the mass energy of the individual nucleons. When talking ...

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Since the graph of sin function is identical to that of a sin wave, I know why the sine function is used in the wave equation The $y=\sin(\omega t)$ part that you mention you are familiar with, starts at (0,0). That is, at time $t=0$ the sine is $y=\sin(\omega 0)=0$. The only thing a phase angle does is to shift the starting point. If a phase angle is ...

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If you remember transformation of functions, $\omega$ would stretch the sine function in the x-axis, and $\phi$ would transform (or move) the sine function along the x-axis. With that in mind, the phase is how far along the sine function is in one period. In phase is when two sine functions have the same phase and period and so have the same peaks and ...

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In the equation $y=\textrm{sin}(\omega t+ \phi)$ $\omega$ is the angular frequency of the oscillator, and $\phi$ is the phase angle. Let's start with the most basic version of this equation, and then build back up to the most general case. If we set $\omega=1$ and $\phi=0$ then we are left with $y=\textrm{sin}(t)$ which in the basic sine function. If we ...

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