# Tag Info

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According to quantum mechanics the time evolution of the universe is described by a path integral that will sum over all histories. If we consider a robot whose processor runs at a clock cycle of $\tau$ to simplify things, then all the possible time evolutions during that period of $\tau$ will contribute to explain the robot's observations, including the ...

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Fortunately for experiments in physics we have better proxies than the accuracies of our five senses. We have detectors and computers and .... With these tools a theory of how the universe is made has been developed, from elementary particles with the theory of quantum mechanics building up the observables around us, to the astrophysical models that fit ...

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Quite a philosophical approach. There is still the reliance on our four other senses in order to make sense of our physical world, however the same approach can be imply to those senses also with the delay in neurological impulses. One must also take into account, as you would call it, the in between frames of other people's perceptions, as well as those ...

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could something else be relative (other then time)? The speed of light is relative. In 1905 it was easy for Einstein to assume that the speed of light (relative to the observer) is independent of the speed of the light source - the assumption was false but sounded plausible since it was a tenet of the universally accepted ether theory. However this ...

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We've already observed time dilation, so we know time isn't linear/constant. See the Experimental confirmation section of the Wikipedia page on time dilation.

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First off, we should take the wisdom of Jack Wisdom to heart: "Calculation of the history of the lunar orbit is fraught with difficulties." While calculating the history may well be fraught with difficulties, calculating the future is hugely problematic. For the sake of argument, I'll ignore that issue. The OP suggests the end of the planet is about 5 ...

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But can time also be measured by just changes in energy, and in the absence of matter? If there are no massive particles present, then general relativity has a symmetry called conformal invariance. In the presence of this symmetry, there is no way to measure time. According to evolutionary universe theories there was a point in the evolution where ...

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Only if matter and energy were not intertwined. How can you exhibit and measure energy without the matter it works upon? Energy is just a property used to explain matter. See summary http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/matter-and-energy-a-false-dichotomy/ Thinking outside the box: Does the idea ...

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First, the concept of matter and energy are entagled since Einstein. Most people have an intuition on the word energy as some untouchable fuild with destructive power,mainly due to hollywood. But energy and mass have a much more specific, mathematical meaning in physics. So instead, let me rephrase the question as "does it makes sense to talk about time in ...

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The conceptual key here is that time dilation is not something that happens to the infalling matter. Gravitational time dilation, like special-relativistic time dilation, is not a physical process but a difference between observers. When we say that there is infinite time dilation at the event horizon we don't mean that something dramatic happens there. ...

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If you have acceleration as a function of speed use the first equation. If you have speed as a function of position use the second equation. $$t(v)=\int_{v_1}^{v}\frac{1}{a(v)} \, \mathrm{d}v$$ $$t(x) = \int^x_{x_1}\frac{1}{v(x)}\, \mathrm{d}x$$ It seems you have acceleration (force) as a function of speed with $a(v) = C_0 + C_1 v$. The first integral then ...

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Ilya Prigogine and the school of non-equilibrium thermodynamics has investigated the emergence of structure in chemistry and biology away from equilibrium. In these cases chemical clocks (and by implication biological clocks) can be seen as complex systems forming structures away from equilibrium. These are refered also as "TEMPORAL DISSIPATIVE STRUCTURES" ...

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The aging of the body has nothing to do with entropy. As has been pointed out, the body is not a closed system. It takes in energy all during its life and the overall thermodynamic state of 2 bodies of different ages but identical everything else (such as fat content, state of hydration, and so on) are equivalent. Aging is caused by many factors such as ...

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3) and 4) don't represent "the time between the events" 1 and 2 in either frame, but you can calculate them if you wish, and as you said these are times that you could apply the time dilation equation to. Basically, to apply the time dilation equation, you must pick the time between two events on the worldline of a single inertial clock, and then you compare ...

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Can time be quantised? Would it be the smallest distance between two photons moving in the same direction or the shortest wavelength? "Can" time be quantized? Yes it can. We have atomic clocks working for us after all, giving us increments of time. Is this phenomenon sufficient to say time in general comes in increments? No. The same is true about ...

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"Using the equation of the time unit I derived for time, we can say now a unit of our time for an observer will be the distance (light will cover) for a unit of time to pass for us (observer)" Is this observer meant to be the one who sees the object with the walls A and B moving at velocity v? If so, then although it's true this observer will see the length ...

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You are quite right: Einstein is using highly idealised concepts in a thought experiment. In general ALL interactions between light and matter take nonzero time. But Einstein is justified in this approach because: As stated by Nikos M in his comment: "Einstein's observation does not need the light to be reflected, one can very well get the same ...

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One way to imagine computing the reflection delay is to assume that the reflection process takes place within the first skin depth of the material. Taking numbers straight from the Wikipedia article, a copper conductor reflecting a 100 MHz (radio) wave would do so within its outermost 6.6 μm. In vacuum, light crosses 6.6 μm in about 20 femtoseconds. Skin ...

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This isn't a complete answer, but John Baez gave a pretty good treatment of this in a series of blog posts (part 1, part 2, part 3, part 4; arXiv paper with some more stuff). Basically, he defines what he calls the "quantropy", which is just the classical entropy formula with $\beta$ replaced by $-i/\hbar$ and the energy replaced with the action. (Note ...

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A logical analysis of absolute motion ongoing within an absolute 4 dimensional Space-Time continuum, leads you to the awareness of the constant motion of all objects. That constant motion turned out to be the speed of light. If one analyzes the concept of constant motion of all objects located within Space-Time, and that this ongoing motion is the equivalent ...

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