Lengths and times relative to S' and S

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In summary, the conversation discusses the proposal of a new perspective on lengths and times relative to two coordinate systems, S' and S. It is given that the length of the path of a ray of light emitted by S' is equal to the length of the path of a ray of light emitted by S. The conversation also mentions the synchronization of clocks located at different positions in the systems. The argument presented may contradict special relativity and the speaker suggests providing a clearer explanation of the idea.
  • #1
arbol
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I propose a new look at lenghts and times relative to S' and S (at least new to me).

Let S' be an x'-coordinate system. Let the x'-axis of S' coincide with the x-axis of an x-coordinate system S, and let S' move along the x-axis of S with velocity v in the direction of increasing x.

Let t' = the time, with respect to S', a ray of light emitted by S' takes to move along the x'-axis of S'.

Let t = the time, with respect to S, a ray of light emitted by S takes to move along the x-axis of S.

Let T = the time, with respect to S, the ray of light emitted by S' takes to move along the x'-axis of S'.

At t' = 0s, the ray of light emitted by S' is located at x' = 0m.

At t' = t'1, the ray of light emitted by S' is located at x' = c*t'1.

At t' = 2*t'1, the ray of light emitted by S' is located at x' = 0m.

At t = 0s, (1) the ray of light emitted by S is located at x = 0m, (2) the origin of S' is located at x = 0m, and (3) t' = t.

At t = t1, (1) the ray of light emitted by S is located at x = c*t1, (2) the origin of S' is located at x = v*t1, and (3) t' = t.

At = t = 2*t1, (1) the ray of light emitted by S is located at x = 0m, (2) the origin of S' is located at x = 2*v*t1, and (3) t' = t.

At T = 0s, the ray of light emitted by S' is located at x = 0m.

At T = T1, the ray of light emitted by S' is located at x = c*T1 = v*t1 + c*t'1 = c*t'1 + v*t'1 = t'1*(c + v).

Note: t1 = t'1. It is given that the length of the path of the ray of light emitted by S' is equal to the length of the path of the ray of light emitted by S.

At T = T2, the ray of light emitted by S' is located at x = 2*v*t1.

T1 = t'1(c + v)/c.

c*(T2 - T1) = |2*v*t1 - (c*t'1 + v*t'1)| = c*t'1 + v*t'1 - 2*v*t'1 = c*t'1 - v*t'1 = t'1*(c - v).

T2 - T1 = t'1*(c - v)/c.

Note: T1 is not equal to T2 - T1, but this inequality does not mean that the clock located at x = 0m and the one located at x = c*T1 are not synchronous. The clock that marks the time T = 0s is located at x = 0m, the one that marks the time T = T1 is located at x = c*T1, and the one that marks the time T = T2 is located at x = 2*v*t'1 (or x = v*T2).

T = T1 + (T2 - T1) = T2 = 2*t'1.
 
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  • #2
arbol said:
Let the x'-axis of S' coincide with the x-axis of an x-coordinate system S, and let S' move along the x-axis of S with velocity v in the direction of increasing x.
I haven't read the whole thing, but you're already contradicting special relativity here. If S and S' are inertial frames, the x' axis would intersect the x-axis with slope v (when the units are such that c=1).

You also need to explain what you're trying to do more carefully. I'm having a hard time following your argument.
 
  • #3
Fredrik said:
I haven't read the whole thing, but you're already contradicting special relativity here. If S and S' are inertial frames, the x' axis would intersect the x-axis with slope v (when the units are such that c=1).

You also need to explain what you're trying to do more carefully. I'm having a hard time following your argument.

Yes. I am even having difficulties following what I am writing. I hope this reply is easier to read.

Let S' be an x'-coordinate system. Let the x'-axis of S' coincide with the x-axis of an x-coordinate system S, and let S' move along the x-axis of S with velocity v in the direction of increasing x, and let the origin of S' coincide with the origin of S at t = t' = 0s.

Let a ray of light emitted by the moving system S' depart from x' = 0m at the time t' = 0s towards x' = x'1 and reach x' = x'1 at the time t' = t'1, and let it be reflected at x' = x'1 back to x' = 0m, and reach x' = 0m at the time t' = t'2.

With respect to the moving system S', the length of the path of the ray of light emited by S' is

2*x'1.

t'2 = 2*x'1/c.

Let a ray of light emitted by the stationary system S depart from x = 0m at the time t = 0s towards x = x1 and reach x = x1 at the time t = t1, and let it be reflected at x = x1 back to x = 0m, and reach x = 0m at the time t = t2.

With respect to the stationary system S, the length of the path of the ray of light emited by S is

2*x1.

t2 = 2*x1/c.

It is given in this thread that x = x'1.

With respect to the stationary system S, the length of the path of the ray of light emitted by the moving system S' is

x'1 + v*t'1 + (x'1 - v*t'1) = 2*x'1 = 2*x1.

Thus, with respect to the stationary system S, the ray of light emitted by the moving system S' takes the time t2 = t'2 to move from x' = 0m to x' = x'1 and back to x' = 0m.
 
  • #4
x'1 + v*t'1 + (x'1 - v*t'1) = 2*x'1 = 2*x1.
Yes, as long as x'=x and t'=t, x'=x and t'=t. That's fact.
 

1. What is the concept of "lengths and times relative to S' and S"?

The concept of "lengths and times relative to S' and S" is based on the theory of relativity, which states that the laws of physics are the same for all observers in uniform motion. This means that measurements of length and time can vary depending on the observer's frame of reference. S' refers to the frame of reference or perspective of an observer moving at a constant velocity relative to an object or event, while S refers to the stationary frame of reference.

2. How do lengths and times change when measured from different frames of reference?

According to the theory of relativity, lengths and times can appear to change when measured from different frames of reference. This is known as the relativity of simultaneity, which means that two events that appear simultaneous to one observer may not appear simultaneous to another observer in a different frame of reference. Additionally, the length of an object can appear shorter when measured from a moving frame of reference due to the phenomenon of length contraction, and time can appear to pass slower for objects in motion, known as time dilation.

3. What is the equation for calculating length contraction?

The equation for calculating length contraction is L' = L * √(1 - v^2/c^2), where L' is the length of the object as measured from the moving frame of reference, L is the length of the object in its rest frame, v is the velocity of the moving frame of reference, and c is the speed of light. This equation shows that as the velocity of the moving frame of reference increases, the length of the object appears to shorten.

4. How does time dilation affect the measurement of time?

Time dilation occurs when time appears to pass slower for objects in motion relative to an observer in a stationary frame of reference. This means that a clock in motion will appear to tick slower than a clock at rest. The equation for calculating time dilation is t' = t * √(1 - v^2/c^2), where t' is the measured time in the moving frame of reference, t is the time in the stationary frame of reference, v is the velocity of the moving frame of reference, and c is the speed of light.

5. How does the theory of relativity impact our understanding of space and time?

The theory of relativity has greatly impacted our understanding of space and time by showing that they are not absolute and can vary depending on the observer's frame of reference. This concept has been confirmed through numerous experiments and has led to the development of technologies such as GPS, which rely on the principles of relativity to accurately measure time and distance. The theory of relativity has also revolutionized our understanding of the universe and has helped to explain many previously unexplained phenomena in physics.

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