How does the length contraction work for proper length?

In summary, proper length is defined as the minimum distance between two events in any frame, and length contraction occurs when measuring the length of an object in a different inertial frame. Some arguments suggest that the events measured from another frame may be different events, as an object is composed of many events and the choice of simultaneous events can vary between observers. The proper length of an object is its length when measured at rest with respect to the observer. The distance between two events is not the same as measuring the length of an object, and the minimum distance between two events can only be zero if there is a time-like interval between them. If the interval is space-like, there is a world line where the distance is minimized.
  • #1
Ashuron
141
0
Well..

Proper length ,from my understanding, is the minimum distance between 2 events in any frame.
Then, how does the length contraction work? suppose someone from other inertial frame try to measure the length..
The length will be contracted to L/gamma..shorter than proper length..

Some arguments from physicsforums seems try to tell that the events measured from another frame are completely different events..
 
Physics news on Phys.org
  • #2
So your understanding is wrong.
It is patent that proper length is the longest. And it is not between two events.
 
  • #3
thx a lot..
btw why not between 2 events?
 
  • #4
Ashuron said:
thx a lot..
btw why not between 2 events?

Length is the distance between two simultaneous measurement events at two point.
 
  • #5
Ashuron said:
Well..

Proper length ,from my understanding, is the minimum distance between 2 events in any frame.
Then, how does the length contraction work? suppose someone from other inertial frame try to measure the length..
The length will be contracted to L/gamma..shorter than proper length..

Some arguments from physicsforums seems try to tell that the events measured from another frame are completely different events..

Two events in one frame are the same events in any other frame. I think what they meant was that an object is composed of many events. When you measure the length of an object, you will not choose the same two events as somebody else who is moving with respect to you. You choose what you think are two simultaneous events (an event at one end of the object and the other end of the object). Somebody else measuring that object will not choose the same events when making their measurement.
 
  • #6
then why my text defined proper length as the minimum spatial separation possible..?
 
  • #7
Ashuron said:
then why my text defined proper length as the minimum spatial separation possible..?

Either you read it wrong, or they are in error. The proper length of an object is the length of the object at rest with respect to you when you measure it. Anything else is Lorentz contracted.
 
  • #8
like in spacetime diagram..let one event is on the origin..and another event at the region of space like interval..
such both event have no causality relationship since their spacetime interval is space like..
there is no situation where the second event is in the region of time-like interval
 
  • #9
Again, the distance between two events is not the same as measuring the length of an object. If you have two events with a time-like interval between them, then the minimum distance you will ever measure between them is if they happen in the same place, and it will be zero. If the interval is space-like, then there is a world line in which the distance is minimized.
 

What is length contraction?

Length contraction is a phenomenon in which the length of an object appears to be shorter when it is moving at high speeds, relative to an observer who is at rest.

What is proper length?

Proper length refers to the length of an object as measured by an observer who is at rest relative to the object. This is the true, uncontracted length of the object.

How does length contraction occur?

Length contraction occurs because of the effects of special relativity. As an object moves at high speeds, its measurement of time and space becomes distorted, causing the object to appear shorter in the direction of motion.

At what speeds does length contraction become noticeable?

Length contraction becomes noticeable at speeds close to the speed of light, which is approximately 299,792,458 meters per second. At these speeds, the effects of special relativity become more prominent.

Does length contraction only occur in the direction of motion?

Yes, length contraction only occurs in the direction of motion. This means that an object will appear shorter only when it is moving at high speeds relative to an observer, and not in other directions.

Similar threads

Replies
63
Views
2K
Replies
17
Views
715
  • Special and General Relativity
Replies
7
Views
974
  • Special and General Relativity
Replies
10
Views
406
  • Special and General Relativity
2
Replies
45
Views
2K
  • Special and General Relativity
Replies
12
Views
734
  • Special and General Relativity
Replies
11
Views
952
  • Special and General Relativity
Replies
29
Views
1K
  • Special and General Relativity
Replies
12
Views
757
  • Special and General Relativity
Replies
11
Views
1K
Back
Top