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15 votes
Accepted

Continued calibration of atomic clocks

My question is how is are the world's atomic clocks continually calibrated to compenstate for the vargaries of the Earth's rotation and orbit around the sun? They aren't. The atomic timescale is ...
BowlOfRed's user avatar
  • 41k
13 votes

Relation between energy and time

There are at least three occasions where the notions of Energy and Time show up together in classical and modern physics. Probably the most elementary situation is related to the fact that the ...
Valter Moretti's user avatar
13 votes

Continued calibration of atomic clocks

Modern metrology supports the issues you address by having multiple time systems, each with their own peculiarities. Any activity that needs a clock to measure time chooses a time system which meets ...
Cort Ammon's user avatar
  • 50.2k
7 votes

Do clocks tick faster when gravitational forces are weaker?

The (relative) rate of clocks depends on the gravitational potential not force. For example, a clock at the center of the Earth would experience no acceleration due to gravity, but would tick slower ...
Eric Smith's user avatar
  • 9,611
3 votes

Do clocks tick faster when gravitational forces are weaker?

Pop sci (e.g., YouTube) regularly says gravitational fields slow clocks, and then the comments are flooded with Flat Space Timers claiming acceleration changes how clocks function, not time itself. Ug....
JEB's user avatar
  • 35.4k
3 votes

Relation between energy and time

Why is energy always related to time in physics. I don't think it is helpful to describe energy as "always related to time" in physics. That being said, there certainly are a number of ...
hft's user avatar
  • 21.8k
2 votes

Relation between energy and time

The way I like to look at it (and which may or may not give you the same amount of intuition as it does to me) is as such: Momentum is what gives rise to changes in position. Clasically, a body ...
CompassBearer's user avatar
2 votes
Accepted

How exactly did Harrison's chronometer circumvent the impulse problem of time-keeping on a moving ship?

Harrison came up with a number of clever designs. In one he made the clock's pendulum mechanism symmetrical about a plane running through its center (i.e., two penduli that were mirror-images of each ...
niels nielsen's user avatar
2 votes
Accepted

Multiple time dimensions in the eternal inflation model

If we put aside the question of dynamics, and just think in terms of a space-time metric, you can certainly have an n-dimensional space in which different regions have different numbers of time ...
Mitchell Porter's user avatar
2 votes
Accepted

Extrapolating time to infinity for a particle moving spirally outward

in which direction should I look to find the particle? To determine this you need to write the equation for the position of the particle in polar coordinates. There is not a shortcut here as “outward ...
Dale's user avatar
  • 103k
2 votes

Could chaos theory and butterfly theory prove that time only exists in the present?

Chaos theory is about studying systems that are highly sensitive to initial conditions, leading to unpredictable long-term behavior despite having deterministic underlying equations. It does not ...
Ansh Tandon's user avatar
2 votes

Does Hamilton's principle allow a path to have both a process of time forward evolution and a process of time backward evolution?

OP asks an interesting question, which we rephrase as follows: Given an action $$S[q]~=~\int_{t_1}^{t_2} \!dt~L(q,\frac{dq}{dt},t),$$ are the stationary action principle (SAP) and Euler-Lagrange (EL) ...
Qmechanic's user avatar
  • 206k
1 vote

Probabilistic behavior of quantum mechanics

If you have two identically prepared systems, say two copies of the state $ \alpha \vert \uparrow \rangle + \beta \vert \downarrow\rangle$, with $\vert \alpha\vert^2+\vert\beta\vert^2=1$, you might ...
ZeroTheHero's user avatar
  • 46.1k
1 vote
Accepted

Does Hamilton's principle allow a path to have both a process of time forward evolution and a process of time backward evolution?

As I understand it you are wondering about the following: What will be the implications when Hamilton's action is evaluated over a time interval where the end point is earlier than the start point? I ...
Cleonis's user avatar
  • 21.4k

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