# What is Special relativity clocks: Definition and 34 Discussions

In physics, the special theory of relativity, or special relativity for short, is a scientific theory regarding the relationship between space and time. In Albert Einstein's original treatment, the theory is based on two postulates:
The laws of physics are invariant (that is, identical) in all inertial frames of reference (that is, frames of reference with no acceleration).
The speed of light in vacuum is the same for all observers, regardless of the motion of the light source or observer.

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1. ### I Is time dilation a real effect?

In the context of SR we know time dilation is basically the rate of change of moving clock's proper time w.r.t. the inertial frame coordinate time. It does mean that in principle the "tick events" of moving clock are compared against the time measurement of clocks Einstein's synchronizated in...
2. ### I On the physical meaning of Minkowski's spacetime model

Hi, I was thinking about the following. Suppose we have a geometric mathematical model of spacetime such that there exists a global map ##(t,x_1,x_2,x_3)## in which the metric tensor is in the form $$ds^2 = c^2dt^2 - (dx_1)^2 + (dx_2)^2 + (dx_3)^2$$ i.e. the metric is in Minkowski form...
3. ### Special relativity and standard configuration

1. list three events and determine position and time of three events in planets frame of reference I think the 3 events are: E1- Spaceship is at planet A and sends the light pulse E2 - light pulse arrives at planet B E3- spaceships arrives at planet B 2.create a diagram showing planets frame...
4. ### I Analyzing Time Dilation in a Spaceship-Mars Scenario

Here is the simple problem from the book, but I have a hard time understanding how to solve it, or how to think about it. A spaceship flies past Mars with a speed of relative 0.985 c to the surface of the planet. When the spaceship is directly overhead, a signal light on the Martian surface...
5. ### B Is velocity the reason for the time dilation effect?

Hello! I try to understand how in different frames clocks tick and stop simultaneously but show different time? I suppose that velocity is reason of time dilation effect but I'm not sure. Thanks.
6. ### B How to measure time in reference frame with clock?

I considered example of time dilation with light clock. I have a question about measuring time in reference frame with clock. If we know that clock move from A to B in the reference frame with clock then what time of motion is measured in this reference frame? (In non-moving reference frame...
7. ### I Clock synchronization for ring-riding observers on rotating disk

Hello, reading the wiki entry for Langevin observers on rotating disk - Born_coordinates I'm struggling with the following quoted sentence: But as we see from Fig. 1, ideal clocks carried by these ring-riding observers cannot be synchronized. I do not grasp why, starting from the figure...
8. ### B SR equation seems to depend on orientation of the 'light clock'

One of my first exposures to special relativity was looking at a 'light clock' where a photon is emitted and captured by a detector whilst traveling on a train. The passenger sees the photon go straight up. The distance traveled by this photon in a given time, t, is c t An observer however...
9. ### B Twins Paradox Thought Exp: What Happens When Reunited?

I have been looking through some of the threads about the twins paradox in relativity. It’s clear there’s a lot of confusion on this, and I am yet one more person very confused on this. So I was thinking about a hypothetical experiment, and I will lay out my hypothesis of what might...
10. ### Time dilatation between straight and curved lines in Minkowsi space

Summary:: Special relativity - 2 astronauts syncronize their clocks and moves in different paths at different velocities, which clocks is left behind? and why? Hi everyone, i have the following problem and I'm not understanding if my strategy to solve it is correct: Two astronauts synchronize...
11. ### I Shouldn't a moving clock appear to be ticking faster instead of slower?

Hi. Im looking into special relativity and everything i found about time dilation on internet seems to say that moving clock appear to tick slower than the stationary one. However what I found about this is following, in § 4. (Physical Meaning of the Equations Obtained in Respect to Moving Rigid...
12. ### Is This the Proper Frame for Your Needs?

The attempt is above
13. ### Calculating elapsed time in different frames

The attempt is above
14. ### Twin Paradox from Moving Reference Frame- Return Journey

Homework Statement a) Alice is observing a small ball of mass m in relativistic motion bouncing elastically back and forth between two parallel walls separated by a distance L with speed u. After each collision it reverses direction, thereby creating a clock. What does Alice observe as the...
15. P

### I Does the *First Postulate* Prohibit different time dilations?

For example, Brian Greene says in The Elegant Universe regarding special relativity and train moving with constant velocity relative to platform: By the principle of relativity or first postulate, "there is no way for an observer on this train to detect any influence of the train's motion. But...
16. ### I Clocks ON a rotating disk: What happens?

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)...
17. ### I Moving Clock: Lorentz Factor Calculation

Hi guys! I want to thank to all the guys which helping us to understand the beauty and mystery of the relativistic theory. Here I just want to share the calculation of Lorenz factor for the moving clock in the frame of reference of the "stationary" observer. This time the clock is not...
18. ### I Clock Synchronization: Jack & Jill's View

Hi, Here me again. I have a question about clock synchronization. Suppose we have train with Jill with two clocks and Jack on the ground. As seen from the ground by Jack, the two clocks on the train (which is moving at v in the x-direction) are running slowly, registering only seconds for each...
19. ### I Special relativity: frames of reference

Hi people, I have a question about the frame of references. Let's have an example: First case: Jill on rocket and Jack stationary on Earth. Jill moves relatives to Jack 0.6c (1.8*10^8m/s). The distance is 18*10^8m. At the zero time Jack and Jill synchronize their clocks. Then Jill starts to...
20. ### B Time Dilation, Interstellar Travel, and "The Forever War"

Dear community, I have no formal education in physics, but I think I have understood some of the basic concepts and ideas in SRT. I am currently trying to find a solution to a problem that came up during my reading of Joe Haldeman's "The Forever War", a Sci-Fi novel that deals with the impact of...
21. ### B Special Relativity: What Time is it?

This question based on the site located here: http://galileo.phys.virginia.edu/classes/252/srelwhat.html The question is: If the object (spaceship) moving close to the velocity of light and I'm as a static object. The time goes slower in the object moving with constant velocity (inertial frame)...
22. ### Time Dilation in the same frame of referance?

Homework Statement A rocket ship is accelerating through space. Clocks P and Q are at opposite ends of the ship. An astronaut inside the rocket ship is beside clock P and can also observe clock Q. What does the astronaut observe about the passage of time for these clocks? Justify your answer...
23. ### I Time dilation (something seemingly paradoxical)

Hello. Consider the following case: Two observers, A and B, moving relative to each other with velocity v. For B, it's A that moves (with v) and so DTb=g*DTa (where DT denotes finite time difference and g is/the Lorentz factor gamma). So, (following the same logic as in Morin's Classical...
24. ### Light hours special relativity time dilation

Homework Statement http://phy240.ahepl.org/Chp1-Relativity-Serway.pdf#page=39 #32 Planet R is 25 lighthours away from Earth. It takes 25 h (according to an Earth observer) for a spacecraft to reach this planet. The clocks are synchronized at the beginning. What is the spacecraft 's time...
25. ### I Calculating Radius and Mass of Disc for Velocity 0.75C

Imagine a disc witch has a radius of R=1000m and a mass M=1000kg, this disc sits on an cube that is considered static it has no velocity in any direction whatsoever. There is a light clock with the length L=17.45240644m (approximately the same as the arc length for 1 degree on the disc θ=1)...
26. ### B Turning Einstein’s train thought experiment on its head

Let us first review Einstein’s train and platform thought experiment which consists of one observer midway inside a speeding train car and another observer standing on a platform as the train moves past. A flash of light is given off at the center of the train car just as the two observers pass...
27. ### I Special relativity thought experiment

The subject of relativity has been haunting me for while now. Everytime i feel i understand a concept, there comes questions withtin that contradict the undestanding. Have been trying to digest the time dilation & symmetry of how it is felt mutually by observers in two different frame of...
28. ### How Do Clocks on Moving Trains Behave Near a Tree?

Homework Statement Two trains of proper length L move toward each other in opposite directions on parallel tracks. They both move at speed v with respect to the ground. Both trains have clocks at the front and back, and these clocks are synchronized as usual in the frame of the train they are...
29. ### EPR paradox and time of collapse

According to the EPR-paradox, if we have a pair of two entangled spin-1/2 fermions A and B and measure z-component of A, B collapses immediately as well(i'm using these letters for both particles and their observers). The 'canonical' solution is then to state that it is not possible to transfer...
30. ### The Mysterious Synchronization of Clocks in Special Relativity

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...
31. ### Two observers must agree what each clock reads....

Homework Statement You are gliding over Earth's surface at a high speed, carrying your high-precision clock. At points X and Y on the ground are similar clocks, synchronized in the ground frame of reference. As you pass over clock X, it and your clock both read 0. (a) According to you, do...
32. ### How does special relativity account for the time on a single moving clock?

Clocks and time are not the same thing. Time is a property of nature observable as changes. Day turns to night, summer follows winter, and rivers flow downstream. Clocks, however, are man made objects that do what we tell them to do. For everyday use we regulate clocks to match the noon-to-noon...
33. ### Special relativity clocks observed from two frames

Homework Statement Observers S and S' stand at the origins of their respective frames, which are moving relative to each other with a speed of .6c. Each has a standard clock, which, as usual, they set to zero when the two origins coincide. Observer S keeps the S' clock visually in sight...
34. ### Do the Principles of Special Relativity Require Synchronized Clocks in K and k?

Consider the following properties of SR clocks. The coordinate systems are the usual K( X,Y,Z,T) and k( x,y,z,t) where k is the coordinate whose origin moves in the positive direction of K. 1.The clocks of K are synchronized with each other using the procedure given in the 1905 paper. Also...