Deriving the time dilation? equation of Lorentz transformation

In summary, the conversation is about a request for help in deriving the Lorentz time equation and understanding its intuition. The equation is used to calculate the time in one inertial reference frame relative to another, taking into account the speed of light, the gamma factor, and the relative velocity between the two frames. The conversation also discusses various attempts at solving the equation and a suggestion to visualize it through a thought experiment. The final equation can be derived by substituting the given equations and using Pythagoras.
  • #1
fignewtons
28
0

Homework Statement


It is not an official question but a request for pointers. I am trying to derive the Lorentz time equation to understand the intuition behind it. My math skills are not very good so it might be an obvious question for you. Please see below for my attempt.
The variables are x, t in one inertial reference frame and x', t' in another inertial reference frame. c is the speed of light, γ is the gamma factor, and u is the relative velocity of the primed IRF, from the perspective the unprimed one.
The official equation (the end solution I want to get) is:
t'=(t-(ux/c^2))/sqrt(1-(u/c)^2)

Homework Equations


I'm using the equations:
γ=1/sqrt(1-(u/c)^2)
x'=γ(x-ut)
x=γ(x'+ut')

The Attempt at a Solution


So far I've been able to isolate t' from the equation x=γ(x'+ut') up to this state:
t'=((x/γ)-x')/u
I've tried substituting ct for x, substituting γ for 1/sqrt(1-(u/c)^2), and other substitutions that by now I've forgotten. It doesn't seem to come to the format I want in the official equation, mainly because I can't seem to isolate t in the RHS or get rid of the u in the denominator. I've been stuck on it for days :( I hope this makes sense!

Any attempts to explain the intuition behind this equation/help me visualize it is welcome too, I've asked my instructor on it but somehow he seems shocked I would ask this question and told me to just try to derive it...

Thanks for reading this over, hope everything actually makes sense!
 
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  • #2
A good way to "derive" this equation is to visualize it on paper by a series of diagrams.

First consider a train moving at a speed v < c along the x direction. Inside the train is a set of mirrors on the ceiling and floor between which a photon is bouncing up and down in the frame of reference off the train. (Ignore absorption of photon etc.)
In a given time t the photon will bounce from the bottom to the top back to the bottom, and travel a given distance d, and will travel at c.If there were a "stationary" observer outside the train watching the photon, it would take a given time t' for the photon to travel from the bottom to the top to the bottom again, and it would cover a given distance d', and it would still move at a speed c.

Draw these two scenarios and use Pythagoras, and note that c is the same in both frames (invariance of the speed of light in any inertial frame) and you will "derive" your answer.
After this try developing the result from your given equations.

Here is a link to this sort of thought experiment, but I urge you to try it and visualize it yourself first before looking at the link.
http://galileo.phys.virginia.edu/classes/252/srelwhat.html
 
  • #3
t'=((x/γ)-x')/u
and substitute x'=γ(x-ut) in the above equation.
After simplifying i think you can get t'=(t-(ux/c^2))/sqrt(1-(u/c)^2)
 

1. What is the time dilation equation in the Lorentz transformation?

The time dilation equation in the Lorentz transformation is given by t' = t/√(1-v^2/c^2), where t' is the time measured in the moving frame, t is the time measured in the stationary frame, v is the relative velocity between the two frames, and c is the speed of light in a vacuum.

2. How is the time dilation equation derived?

The time dilation equation can be derived using the principles of special relativity and the Lorentz transformation. It takes into account the fact that time is not absolute and can vary depending on the relative motion between observers.

3. What does the time dilation equation represent?

The time dilation equation represents the difference in time observed by two observers in different frames of reference. It shows that time is relative and can appear to pass at different rates depending on the relative motion between the two observers.

4. Why is the time dilation equation important?

The time dilation equation is important because it is a fundamental equation in special relativity, which is a crucial theory in modern physics. It helps us understand the relationship between space and time and explains the observed phenomena such as the twin paradox and the behavior of particles at high speeds.

5. Can the time dilation equation be applied to all situations?

Yes, the time dilation equation can be applied in all situations where there is relative motion between two frames of reference. It is a universal equation that holds true regardless of the speed or direction of the motion, as long as the speed is not equal to the speed of light, which is the ultimate speed limit in the universe.

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