Clocks Definition and 248 Threads

If the speed of light would change in the universe without any other natural constant changing, would all clocks be affected in the same way by this? This is implied by Einstein in this paper on page 368 http://myweb.rz.uni-augsburg.de/~eckern/adp/history/einstein-papers/1912_38_355-369.pdf...

Special relativity is replete with examples of turning mirrors into clocks. Place two mirrors across from one another, bounce light between them, and measure the time. But as I thought about this, when a photon hits the mirror, it is absorbed by an electron which moves to a higher energy...

In Classical GR the metric tensor ##g_{\mu\nu}## determines the length of rods and ticking of clocks while the connection ##\Gamma^{\alpha}_{\mu\nu}## determine the equation of geodesic (the free fall motion of particle). Furthermore, in GR the Levi-Civita connection is uniquely determined by...

Special relativity says that all clocks will show same time dilation, irrespective of clock mechanism. But Time period of a clock is a formula that must continue to hold even if time dilates. Let us look at a tuning fork clock. Here time period depends on the dimensions of the vibrating...

Homework Statement A rectangular structure carries clocks at its four corners. The clocks are synchronized in the structure’s rest frame, in which it has length L =4ft and width W = 3ft. In our laboratory frame the rectangle is moving in the positive x direction at speed v = 0.8c. As the clock...

Homework Statement My professor gave us a werid question which is as follows In the laboratory frame, two clocks are synchronized and measure two light sources at the same time situated at 3 years in time axis and 3 light years and 2 light years in x-axis >At what velocity is the frame ##S'##...

Homework Statement Two atomic clocks are synchronized. One is placed on a satellite, which orbits around the Earth at a high speed for a whole year. The other is placed in a lab and remains at rest, with respect to the earth. You may assume that both clocks can measure time accurately to many...

I looked for an answer to this question other places but found none. There is a puzzle going around that people are getting the answer wrong to. No surprise there. According to the proofs I found for it on the internet, my assumptions were true and I did arrive at the right answer (38...

Hi Couldnt figure this out U have 2 identical clocks where a pulse of light goes from a light source (a), reflects off a mirror (b) and goes to the end (c) A person is stationary wrt one clock and another clock is in a spaceship moving, relative to the observer, in the direction v at velocity...

The experiment done by Hafele & Keating took clocks around the world in two directions and compared the readout to a static clock to measure time dilation effects. Everything fitted nicely with Einstein’s predictions. To avoid confusion let’s move the clocks way out in space to a real inertial...

I just overheard an engineer saying "There are no two clocks in the world that tell identical time". She was describing a time syncing mechanism to another engineer, but it made me think... In theory, can something large enough to be used as a clock become fully entangled with a copy of...

Pendulum clock running rates can be adjusted by changing the length of the pendulums. Likewise the running rates of mechanical and electronic crystal clocks can be changed and adjusted. Can the running rate of an atomic clock also be adjusted? It doesn’t seem like there could be any way to...

Hello. I want to clear a doubt on Special Relativity, time dilation and clocks. If we get an accurate clock and make it orbit the, for example, Earth very, very fast, will the actual mechanical clock lag behind from the accurate clocks on Earth? The thing in this question is about the actual...

Is there any way to synchronize two clocks already in relative inertial motion? If so, how? And I am not sure exactly what “synchronize” would mean in that context. Maybe it would mean that their readings, or at least their running rates, would match when their relative motion was stopped? There...

Hi I can't see the error in this can someone please explain where I went wrong? A man is in a spaceship traveling at a constant velocity He makes 2 identical tubes of length L with a mirror at one end, tube a and tube b He has a single light bulb. Next to the bulb is a detector. He carefully...

Does anyone know if any mechanical clocks have ever been accurate enough to show time dilation? (That would be a clock with a spring-mass harmonic oscillator.) Is there any reason to suspect they might not show the same thing as the atomic clocks? (Pendulum clocks would not, for example. They...

In the rest frame , the measured time interval is the time elapsed between the two ticks (so two events T1and T2) of one clock. In moving frame,the time elapsed between the two ticks T1and T2 are measured by the two synchronized clocks kept at two different places x'1 and x'2. The...

Two clocks A and B are orbiting a non-rotating planet. Each clock periodically transmits its current time value via a radio signal and the other can receive that value. Their orbits are in closely-spaced parallel planes and both orbits are the same distance from the planet. The two clocks are...

I was reading about the Ehrenfest Paradox and it got me thinking about something (that I think is) similar: Suppose we take a large, flat, and rigid disk, and we attach to various parts of it a number of clocks (some very close to the center of the disk, some along the edge, others in between)...

Following scenario: A rocket measuring 10 lightseconds in length accelerates near instantaneously to v=0.4c. Pre-acceleration two clocks placed at the endpoints of the rocket were synced. What will be the time difference between the two clocks post acceleration? I tried to figure it out...

Steven Weinberg has lately been critical of QM. He now also has a technical paper out called 'Lindblad Decoherence in Atomic Clocks', available on arxiv. Here is the abstract: It's a short paper (6 pgs of text), arguing for objective collapse (a la GRW/Diosi-Penrose/etc) instead of...

Will the synchronized clocks placed in an inertial frame remain synchronized forever?

Is the term "Centon", as a unit of time used in Battlestar Galactica copyrighted? How would I go about finding this out? I was thinking about how people would deal with measuring time on other planets when I got to thinking about decimal time and what the units were called. Using seconds...

In the way I was taught about special relativity, time dilation is like the fundamental building block from which you derive things like relativistic mass and length contraction. So it has always struck me as quite odd, that the derivation of time dilation (in some sense the basis of special...

A new entry for Physics Forums Insights has been posted https://www.physicsforums.com/insights/spacetime-diagrams-light-clocks/ For now, please use this thread to comment.

Why is it that for two clocks that are synchronised in one frame, S, but not in another, S', is there an offset in the time by a factor of ##\frac{Lv}{c}##, as measured in S'. Where L is the proper length of the body, as measured in S. I'm confused as to why there is not a factor of ##\gamma##...

Hi, I'm looking for some kind of simulation for time dilation where you can add several clocks to a 2D plane, synchronize them, give them velocities and accelerate them. For example to simulate the twin paradoxon including the acceleration necessary to (at least) one clock to reunite them. I...

For those few of you close to Mystic, CT I would like to mention that the Mystic Seaport Museum has a exhibit on the clocks of John Harrison. It is closing March 28 so there is not too much time left. Here is a link http://www.mysticseaport.org

I don`t understand how synchronization of clocks can be made in an accelerating frame. let`s put a source of light at the center of an accelerating rocket. From it, many pairs of pulses are emitted one at a time in two opposite directions. Because the source is located at an equidistant from two...

Are measuring rods and clocks(the ones that are used as reference to ascertain LC and TD of the relatively moving rods and clocks) left out of the theory in principle?

I am hopeful someone can give me a quick lesson here. I have an idea that time does not slow as one's velocity increases (bear with me, please). I'll state this in familiar terms with a person on a train vs platform and the light beam traveling vertically from the ceiling (P1) to the floor of...

I am really very new to chemistry and physics, although I hope to study in the future. I have a question regarding chemical clocks. Is it possible to gage time using a specific chemical clock or chemical reaction that you may know of? my first,idea was standard chemical clocks like the...

NOTE: This is NOT a homework problem. I created this one myself based on some problems I have seen, with specific numbers used to make calculation clean and easy. Tl/dr version: in a round trip to a star, will the "moving clock" run slower on the way there but faster on the way back due to the...

I had this questioning about the light clock on another thread, and DaleSpam suggested that I open my own thread, so here it is. I was asking if the light clock mind experiment was not contradicting the reference frame principle. I added that to my drawings: And DaleSpam answered this: So...

Kind of long winded, but I would appreciate a second veiw on untangling EA's thinking about this. § 2. On the Relativity of Lengths and Times We imagine further that at the two ends A and B of the rod, clocks are placed which synchronize with the clocks of the stationary system, that is to say...

Homework Statement It is not a homework question.I am trying to understand the concept in the attached diagram but I stuck.Hope someone can help Homework EquationsThe Attempt at a Solution Please see the lower part of the note,stating that Δt' = Δt/γ.However,imagine you are in the moving frame...

[Mentor's note: This thread was split off from https://www.physicsforums.com/threads/time-dilation-and-redshift-for-a-static-black-hole-comments.835277/ as clarifying misunderstandings about time in general is off-topic in a thread about the specifics of time dilation around a black hole]...

Let's say we have a clock that work like this , districts beam of lights are sent in constant time gaps (created by a crystal or some other radioactive process) to a sensor. the sensor is connected to a counter that counts the number of beams, and here we have our clock. Now if we put 2 clocks...

This is the title of a new paper published by two Portuguese scientists (see http://www.nature.com/srep/2015/150723/srep11548/full/srep11548.html or http://www.nature.com/srep/2015/150723/srep11548/pdf/srep11548.pdf). They developed a math model of the synchronization of the two clocks and the...

Assuming the spatially flat FRW metric for simplicity: $$ds^2=c^2dt^2-a(t)^2(dx^2+dy^2+dz^2)$$ where ##t## is cosmological time, ##a(t)## is the scaling factor and ##x,y,z## are co-moving Cartesian co-ordinates. Light freely propagating along the ##x##-direction follows the null geodesic, with...

Let us assume that an observer is stationary at the origin in expanding space. We assume the FRW metric near the origin is given by: $$ds^2=-dt^2+a(t)^2dr^2$$ Let us assume that the observer measures time by bouncing a light beam at a mirror that is at a constant proper unit distance away from...

If I have a "train" at the "platform" and wish to send the train accelerating to near-C velocity in near-zero time from my frame. I presume that there is no theoretical limit on the acceleration (as far as SR goes). I presume that the clocks throughout the train will all appear barely to...

I believe length contraction always makes more sense when integrated with reminders of relativity of Simultaneity. Let's say the engines are at the back end of each rocket. For the viewer "A" in the initial frame, they begin moving and continue accelerating simultaneously, and clocks next to...

I was looking at this because well i wanted to. http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/Special_relativity_clocks_rods/index.html And i worked something that if it was right i would be fantastic. But i can't really believe its this easy.

I had asked this about 2 years ago - but for the life of me cannot find it. Please feel free to cancel this if you can find my OP. Anyhow my question was this: A "train" passes by at significant relativistic speed, along the "x" axis. "Platform" observer peers in windows of train as it passes...

I was reading an article about synchronizing clocks on the rim of a rotating disc with a central, inertial clock. I was wondering how is this possible or have I misinterpreted something. Clocks on the rim tick slower than the central clock because they move relative to the center, so I don't...

This paper, http://arxiv.org/abs/1501.00996, proposes using atomic clocks for gravitational wave detection. It sounds similar to other ideas involving pulsar timing experiments. The twist here is utilizing satellites to provide a wide base for improved sensitivity. Sounds like an inexpensive...

Homework Statement A watch gains 3 minutes every hour. If it is set right at 11 a.m. on February 21st, 2012, when will the hour hand of this defective watch and a correct watch be at the same position? A) 9 p.m. on February 21st, 2012 B) 11 p.m. on February 28th, 2012 C) 11 a.m. on March 2nd...

Suppose that we do not have any way to measure distance, but do have clocks. There are N observers, who can all see the distant events, say spaceships taking off and landing on far away planets. The question is: assuming the speed of light is constant, can we deduce the distance to the events...

Phase difference between clocks with distance Homework Statement Derive Phase difference between clocks with distance Homework Equations I honestly don't understand how this equation ΔT = vD/c2 is derived/figured out. The Attempt at a Solution We haven't covered Lorentz...