Questions tagged [time]
Time is defined operationally to be that which is measured by clocks. The SI unit of time is the second, which is defined to be
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$i\epsilon$ prescription for finite systems [closed]
What is physical interpretation of path integral for finite time and finite epsilon (i.e without taking limits time->+-inf, epsilon->0)? Does it mean you are doing some finite temperature qft ...
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What is the difference between material time derivative and total time derivative of a tensor field? [closed]
I consider material coordintes as $(X_1(t),X_2(t),X_3(t),t_0),$ ($t_0$ arbitrary) and space coordinates as
$(x_1(t),x_2(t),x_3(t),t).$
$\textbf{Remark.}$ I am interested just in dim=3.
We consider a ...
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Relation between energy and time
I would like help in understanding something that has been causing me a lot of trouble recently: Why is energy always related to time in physics?
Examples include the 4-momentum, the energy-time ...
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Continued calibration of atomic clocks
First off I am not well versed in physics, but as I understand things the second is defined by the ceasium fountain clock which is calibrated as follows How was the first atomic clock calibrated?. Now ...
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I need an explanation for the time derivative omissions when solving for the Lagrangian of a system [closed]
So I have been self-studying Landau and Lifshitz’s Mechanics for a little bit now, and I have been working through the problems, but Problem 3 is giving me some trouble. I solved the Lagrangian ...
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Do clocks tick faster when gravitational forces are weaker?
A professor last year taught us that "gravity slows clocks," when teaching about the relationship between gravity and time. This led me to think about places, such as intergalactic space, ...
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Probabilistic behavior of quantum mechanics [closed]
In a hypothetical scenario, if I were to measure the quantum spin of an electron and it showed "up," and then I traveled back in time without changing the initial conditions, would measuring ...
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Does Hamilton's principle allow a path to have both a process of time forward evolution and a process of time backward evolution?
This is from Analytical Mechanics by Louis Hand et al. The proof is about Maupertuis' principle. The author seems to say that Hamilton's principle allow a path to have both a process of time forward ...
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How exactly did Harrison's chronometer circumvent the impulse problem of time-keeping on a moving ship?
According to folklore, around the time of the exploration of the New World, there was a quandary regarding how to measure time on the open sea. Time keeping then was based on the pendulum clock, which ...
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Multiple time dimensions in the eternal inflation model
From a lecture by Prof. Kaiser, I reckoned that according to the Eternal Inflation model, it is possible that all of the 10500 topologies posited by string theory could exist somewhere in the region ...
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Extrapolating time to infinity for a particle moving spirally outward
If I have a particle moving radially away from me in a straight line and I extrapolate time to infinity, I could see the particle in a particular direction (given enough time for the light to reach me)...
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Could chaos theory and butterfly theory prove that time only exists in the present? [closed]
I am sorry if this were to sound dumb but, chaos theory is about reconizing patterns and the universe itself can only repeat it self
, would that mean that time only exist in the present cause if time ...
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If time reversal symmetry was preserved would past and future notions be defined
If time reversal symmetry was preserved would someone be able to define future as a time interval from a given time moment as measured by a clock (assuming they would still function as normal)?
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Gravitational time dilation near the Earth [closed]
I recently read the statement that near the Earth, in the Newtonian weak gravitational field, gravity is 99.9999% mainly due to "curvature of time" (ie gravitational time dilation), and only ...
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Does it make sense to talk about time in absence of matter? [duplicate]
The equations of general relativity should predict (although I might be wrong) that in absence of mass the spacetime is everywhere flat. That is, time is the same everywhere. However, I'm not sure ...