Tag Info

New answers tagged

0

I looked at the previous discussion that you had about this here in the comments and I think I may have an idea about what is going on here, but I expect someone else will post a better reply here. First I want to quote three of John Rennie's comments. See this article on the block universe. Note that most us regard this as philosophy not physics ...


0

If I do not misunderstand your question, what you are asking refers to what is called block universe. In the block universe, time does not unfold, but is equivalent to the the spatial coordinates in the sense that all the time past present and future already exists, in the same way that the negative axis, the origin, and the positive axis direction in space ...


0

Confusion about Length Contraction [...] if one object is moving at a speed relative to another object, shouldn't this movement affect [...] Talk about "length contraction" (or "time dilation") is inherently confusing; it is improper and should be avoided. In the typical "cosmic ray generated atmospheric muon" example we have the following unambiguous ...


0

the key is the word "perception" no person can get another person's perception of anything. the question could be re-worded to be more amenable to physics by asking something about the physical world of matter and energy not one's internal perceptions, just a suggestion.


2

Whether or not time is continuous or has some sort of discrete time step, consider the following. Imagine you had a very powerful computer at your disposal, or that the laws of physics happened to be simple enough that we could simulate something as complex as a sentient, self-aware organism using it. Now, we hit "start" on our simulation, and wait a few ...


0

I think we're getting into the philosophical and metaphysical. Perhaps the flow of time is an illusion in the sense we believe it to be. If we take the points on a graph, we can see a proportionate of them simultaneously, whereas we don't perceive "all time" instantly. Not only can we record a point in the past, time appears to flow from the past, into the ...


1

Length is contracted the other way, we just don't notice it because muons are pointlike particles (as far as anyone knows), and a length of zero is still zero no matter how much you contract it. If you had a beam of muons spaced a fixed distance apart (and yet somehow their "decay counters" only start at $50\text{ km}$ altitude), then it would be a ...


1

Don't confuse time dilation and length contraction,(even if length contraction is a consequence of time dilation) because there is no length contraction for the distance between two reference frames. The length (or distance) must be found in one reference frame, and the observer must be in another reference frame, he may not be part of the reference frame of ...


0

Short answer: Yes, length contraction is a symmetric transformation between reference frames. However... You may not like this answer, but I think it's far easier to regard muon decay via the concept of time dilation rather than length of contraction. Reason is, from the standpoint of the muon it's not moving (and yes the Eath is moving but it's not ...


0

Well, Lorentz transformation and whole special relativity gives us short qualitative answer - time dilation and length contraction are very similar. Sitting on Earth we see muons with slower decay rate, because of time dilatation. Being a muon, we calculate time in our own frame of reference - so to keep calculations clear, we need to contract length ...


0

Two questions and two errors: The (hypothetical) point of view of the photon is not "frozen" because you need time to perceive something frozen. But the photon has proper time zero, everything is reduced to one instant, thus nothing can be frozen. "Dodge" a photon: Information is transmitted with light speed. As the photon is moving with light speed it is ...


2

A photon cannot be said to have its own inertial reference frame, because inertial reference are defined to be a family of coordinate systems that satisfy the two fundamental postulates of SR, one of which is that light moves at c in all frames. You could construct a coordinate system where the photon was at rest, but since this coordinate system wouldn't be ...


1

The "g-force" you would experience if you were to "hover" at Schwarzschild coordinate $r$ away from a spherical body of mass $M$ is given by: $$g=\frac{GM}{r^2 \sqrt{1-\frac{2GM}{c^2r}}}$$ (This only applies to bodies held at a fixed value of $r$. A body in freefall experiences no acceleration, for example. If $r$ is changing in some fashion then then ...


1

There are two types of time dilation: dilation caused by being near a large body, and dilation caused by traveling very fast relative to another observer. Relativistic time dilation plays a bigger role for astronauts aboard a space station similar to the ISS. Even though velocity and gravity produce opposite time dilation, in this scenario, time dilation due ...


1

Have a look at my answer to Time Dilation Effects from simply being on a spinning planet orbiting a star in a rotating galaxy in an expanding universe.. Compared to an observer far from the Earth, time at the Earth's surface runs more slowly by a factor of 0.9999999993. Over a 70 year lifespan this makes a difference of about 1.5 seconds. So the man in ...


0

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 ...


1

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 ...


2

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 ...


-1

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 ...


1

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.


5

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 ...


1

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 ...


1

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 ...


6

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 ...


3

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. ...


0

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 ...


0

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" ...


4

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 ...


1

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 ...



Top 50 recent answers are included