Misunderstanding time dilation and length contraction

In summary, the conversation is about a light signal moving between mirrors and being detected by observers standing outside and moving with the system. The textbook states that the click rate will be the same regardless of the direction of movement, but the speaker doubts this. They explain the time dilation and length contraction for each observer, but also question where they may have gone wrong in their calculations. Finally, they suggest that the movement of the apparatus during the clock tick may affect the distance traveled by the light and therefore affect the results.
  • #1
Gavroy
235
0
hi

sorry about my english. i am from france.
i have a few questions about the image i have found in my schoolbook that i attached to this post.

there is a light signal moving up and down and each time it reaches the upper mirror this is somehow detected. there are also two observers: one standing outside(oberserver 1) and one moving with the system and now my textbook says that no matter whether this thing is moving horizontal(as the arrow shows) or vertical(not shown in this picture) to the oberserver standing outside, this guy would detect the same click rate, but i highly doubt it.

let me start with the observer moving with the aperature. he is the one who measures no time dilation as he is moving with the system and measures no length contraction, so the time he waites for a click is t=2l/c where l is the length of this thing.

while the oberserver standing outside will measure a time dilation when the aperature is moving horizontal to him.
that means that he is just waiting: t=2l/c*(1-v^2/c^2)^(1/2) for a click.

WHILE

if the aperature is also moving vertical than there will also be a length contraction and therefore: t=2l/c as both square roots cancel out.

but where am i wrong?
 

Attachments

  • special relativity.jpg
    special relativity.jpg
    10.5 KB · Views: 435
Physics news on Phys.org
  • #2
Gavroy said:
WHILE

if the aperature is also moving vertical than there will also be a length contraction and therefore: t=2l/c as both square roots cancel out.

but where am i wrong?
You forgot to take into account that the apparatus moves during the clock tick. So the distance traveled by the light is not simply twice the contracted length between the mirrors.
 
  • #3
perhaps this will be more clear:

www.phinds.com/time dilation
 
Last edited by a moderator:

FAQ: Misunderstanding time dilation and length contraction

What is time dilation and length contraction?

Time dilation and length contraction are two phenomena predicted by Einstein's theory of relativity. Time dilation refers to the difference in the passage of time between two observers in relative motion, while length contraction refers to the apparent shortening of an object's length in the direction of its motion.

How do time dilation and length contraction occur?

Time dilation and length contraction occur due to the fundamental properties of space and time. According to Einstein's theory of relativity, the laws of physics are the same for all observers, regardless of their relative motion. This means that the perception of time and space can vary for different observers based on their relative velocities.

Can time really slow down or objects really shorten?

While it may seem counterintuitive, time dilation and length contraction have been confirmed through numerous experiments and observations. For example, the famous Twin Paradox thought experiment demonstrates how one twin who travels at high speeds will experience less time than the other twin who remains on Earth. This has been observed in experiments with atomic clocks and high-speed particles.

How does time dilation and length contraction affect our daily lives?

In our daily lives, the effects of time dilation and length contraction are negligible because the speeds at which we move are relatively slow compared to the speed of light. However, these phenomena are important to consider in technologies such as GPS, which relies on precise time measurements to function accurately. Without taking into account the effects of time dilation, GPS would be off by several kilometers.

Is there a limit to the effects of time dilation and length contraction?

According to Einstein's theory of relativity, there is a limit to the effects of time dilation and length contraction. This is known as the speed of light, which is the fastest speed at which anything can travel. As an object approaches the speed of light, time dilation and length contraction become more extreme. At the speed of light, time stops completely and length contracts to a point. This limit on the effects of time dilation and length contraction is a fundamental principle of the theory of relativity.

Similar threads

I What causes time dilation and length contraction
Replies
10
Views
1K
I Question about length contraction
2
Replies
45
Views
4K
B Why does length contraction occur and how does it relate to time dilation?
2
Replies
63
Views
4K
B Check my understanding of Time Dilation and Length Contraction
Replies
11
Views
1K
B On time dilation and length contraction
Replies
34
Views
3K
I Length Contraction & Time Dilation: Proving It
Replies
5
Views
2K
B Reciprocal time dilation
Replies
14
Views
519
I How time dilation is a permanent change and length contraction not?
Replies
13
Views
1K
I Length contraction and time dilation
2
Replies
36
Views
3K
I Relativity of Simultaneity and Length Contraction
2
Replies
54
Views
2K

Hot Threads

Recent Insights

Back
Top