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Results tagged with time-reversal-symmetry
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user 164488
The theoretical symmetry of physical laws under the transformation of time reversal, that is t -> -t.
4
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Is it legal to add two physical quantities that behave differently under time-reversal, pari...
In physics, can we legally add two physical quantities that behave differently under time-reversal or parity? For example, let $\vec{a}$ and $\vec{b}$ are two observables. Let $\vec{a}$ flips sign und …
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2
votes
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answers
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Does it make sense to say that the action is even or odd under time reversal?
The action of a system in mechanics is an integral over time defined as $$S[x(t)]=\int\limits_{t_1}^{t_2}L(x,\dot{x},t)dt.$$ Here, the time $t$ is integrated making the left hand side depend only on t …
- 12.3k
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Cases of various time symmetries
Is it possible to cook up three physically relevant examples where the Lagrangian has explicit time dependence but the system still has one of the following?
time-reversal invariance,
time transla …
- 12.3k
2
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1
answer
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Why does the subclassification of fields under parity require the quantum theory?
The fields of relativistic field theory (scalars, vectors, tensors, and spinors) are all defined via their transformation properties under the restricted Lorentz group (which excludes discrete spaceti …
- 12.3k
0
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Square of the Feynman amplitude for $a +b\to c+d$ and its reverse
In quantum field theory, if a process $a +b\to c+d$ is allowed by a certain interaction Lagrangian (hermitian), the reverse process, $c+d\to a+b$, must also be allowed (as far as I understand) by the …
- 12.3k
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answer
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Why is time-reversal represented by an antilinear and antiunitary operator? [duplicate]
Operators related to physical transformations in quantum mechanics are usually unitary and linear except time-reversal which is both antiunitary and antilinear. What is the explanation for this differ …
- 12.3k