Relativity and Distance Measurement in Physics | PF Community Discussion

[moonman239_2]

Hello PF members!

First of all, let me start off my post by admitting that I have created a duplicate account. My original account was banned for a good reason.
Now, I am studying physics. More specifically, I'm studying relativity. I trust that you all will help me understand what I am studying.

Anyways, I have a question. Einstein said that the speed of light is the same, no matter where you are or how quickly you are moving. However, due to the effect that velocity has on time, an observer traveling near the speed of light will think that another object is further away than it actually is. Because of this, he will disagree with a stationary observer on how far he actually is from the object. So how can the traveling observer calculate his actual distance correctly? Or is space-time set up such that the both calculations are correct, if you know what I mean?

 

[ghwellsjr]

Hello PF members!

First of all, let me start off my post by admitting that I have created a duplicate account. My original account was banned for a good reason.
Now, I am studying physics. More specifically, I'm studying relativity. I trust that you all will help me understand what I am studying.

Anyways, I have a question. Einstein said that the speed of light is the same, no matter where you are or how quickly you are moving. However, due to the effect that velocity has on time, an observer traveling near the speed of light will think that another object is further away than it actually is. Because of this, he will disagree with a stationary observer on how far he actually is from the object. So how can the traveling observer calculate his actual distance correctly? Or is space-time set up such that the both calculations are correct, if you know what I mean?

An observer traveling in a frame at near the speed of light will think that another object is closer than the frame says it is, not further.

Basically, according to SR, each observer uses radar methods to establish distances and assigns the time of the measurement to the average of when the radar pulse was sent and received. This results in a consistent method of measurement and allows each observer to construct a frame of everything out there, although each frame will be different but there is no way to say that one of them is actually correct and the others actually not correct, so yes, both are correct.

 

[Nugatory]

Einstein said that the speed of light is the same, no matter where you are or how quickly you are moving. However, due to the effect that velocity has on time, an observer traveling near the speed of light will think that another object is further away than it actually is. Because of this, he will disagree with a stationary observer on how far he actually is from the object. So how can the traveling observer calculate his actual distance correctly? Or is space-time set up such that the both calculations are correct, if you know what I mean?

You will get nowhere in studying relativity if you do not clearly understand that the bolded text above is wrong. One way to see this is to consider that right now, even as we speak, you are moving at .99c relative to some observer somewhere - but does this mean that you think your desk is farther away from you "than it actually is"? Of course not.

You need to back up, try to forget everything that think you know about time dilation and length contract contraction. Study and understand Einstein's train experiment about the relativity of simultaneity, then the Lorentz transformations; only after that should you think about time dilation and length contraction, and you should do so by deriving them from the lorentz transforms.

 

[berkeman]

Thread locked.

 

[sardar]

I can say that Einstein's theory of relativity has been extensively tested and proven to be accurate. The concept of time dilation and length contraction, where an observer traveling at high speeds experiences time and distance differently than a stationary observer, is a fundamental aspect of this theory.

To answer your question, both observers will calculate the distance correctly in their own frame of reference. This is because space and time are interconnected in relativity, and the concept of distance is relative to the observer's frame of reference. However, they will have different measurements due to their relative speeds.

To accurately understand and calculate the distance between objects in different frames of reference, we use mathematical equations and transformations that take into account the effects of relativity. These equations have been tested and proven to be accurate in predicting the behavior of objects in different frames of reference.

In summary, the concept of distance measurement in relativity is complex but can be accurately calculated using mathematical transformations. The key is to understand that distance is relative to the observer's frame of reference and that both measurements are correct in their own frame. I hope this helps in your understanding of relativity.