Uncovering the Mystery: Slowing Time on a Plane Explained

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Discussion Overview

The discussion revolves around the concept of time dilation experienced by two planes traveling in opposite directions relative to the Earth's rotation. Participants explore the implications of using the US Naval Observatory as a reference frame and the effects of Earth's rotation on time measurement. The conversation touches on theoretical aspects of relativity, reference frames, and the nature of motion.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant questions why time would move slower on the eastward plane compared to the westward plane when both are at the same speed and height, suggesting confusion over the reference frame used.
  • Another participant notes that the US Naval Observatory is not an inertial reference frame due to the Earth's rotation.
  • Some participants reference the Hafele & Keating experiment as relevant to the discussion of time dilation.
  • There is a suggestion that the initial reference frame being on Earth does not negate the effects of time dilation, as the Earth is in motion relative to other celestial bodies.
  • One participant expresses uncertainty about the implications of uniform motion on time dilation, particularly when considering observers on Earth versus those in space.
  • Another participant asserts that rotation can be considered absolute, while linear velocity is relative, which may clarify some aspects of the discussion.
  • One participant expresses that they are not yet at a level to understand the mathematical aspects of the discussion but is eager to learn.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement regarding the nature of reference frames and the implications of Earth's rotation on time dilation. Some concepts are clarified, but no consensus is reached on the interpretation of time dilation in this context.

Contextual Notes

Limitations in understanding arise from the complexity of reference frames, the nature of motion, and the mathematical underpinnings of relativity. Participants express varying levels of familiarity with these concepts, which affects the depth of the discussion.

Who May Find This Useful

This discussion may be of interest to those exploring concepts in relativity, time dilation, and the implications of reference frames in physics, particularly students or enthusiasts seeking to deepen their understanding of these topics.

kuahji
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I'm not sure if this has been asked/discussed before or not. I tried to look but couldn't find a thread, so if there is one please direct me to it.

In this book I'm reading it states that if two planes start off at say the US Naval Observatory, if one goes eastward & the other westward, time will move slower on the plane going eastward. Both planes travel at the same speeds, same height, etc. The reason the book states is because the plane traveling westward goes against the rotation of the Earth. If the US Navel Observatory is the reference frame I don't understand why time one way is slower than the other. If the reference frame was in outer space I could see why (you'd see the plane going eastward at say 100kph + the speed of the Earth's rotation).

Perhaps I'm over thinking this one or perhaps I don't understand as much as I thought I did. Any thoughts?
 
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I havn't herd anything about that before.
What book are you reading?
 
The US Naval Observatory is not an inertial reference frame, it is on a rotating Earth.

Garth
 
Go to google and search on Hafele & Keating
 
kuahji said:
I'm not sure if this has been asked/discussed before or not. I tried to look but couldn't find a thread, so if there is one please direct me to it.

In this book I'm reading it states that if two planes start off at say the US Naval Observatory, if one goes eastward & the other westward, time will move slower on the plane going eastward. Both planes travel at the same speeds, same height, etc. The reason the book states is because the plane traveling westward goes against the rotation of the Earth. If the US Navel Observatory is the reference frame I don't understand why time one way is slower than the other. If the reference frame was in outer space I could see why (you'd see the plane going eastward at say 100kph + the speed of the Earth's rotation).

Perhaps I'm over thinking this one or perhaps I don't understand as much as I thought I did. Any thoughts?

I'd have to dig a bit for supporting references, but your book has it right. To make the observation more specific by pinning down the details, when the two planes next meet (are in the same point in space-time) the westward moving one will have more elapsed time on its clock.

What I don't quite understand is what you don't understand.

Would it help you to write down some math?
 
scott1 said:
I havn't herd anything about that before.
What book are you reading?
Einstein for dummies... :-P I'm reading it on the side from classes for fun.

Garth said:
The US Naval Observatory is not an inertial reference frame, it is on a rotating Earth.

Garth

I thought there could be no abosulte at rest reference frames... You could say the universe is rotating around the Earth.

yogi said:
Go to google and search on Hafele & Keating

This is what I was reading about.

Basically, I thought it didn't matter if the intial reference frame was on Earth. Because in theory you could say the Earth is moving around the Sun, & the sun around a black hole (in theory).

pervect said:
I'd have to dig a bit for supporting references, but your book has it right. To make the observation more specific by pinning down the details, when the two planes next meet (are in the same point in space-time) the westward moving one will have more elapsed time on its clock.

What I don't quite understand is what you don't understand.

Would it help you to write down some math?

I'm not at that level yet to understand the math. I'm sure when I catch up the ideas will click better. I just thought from what I read you could say the Earth is standing still & the universe is rotating around the Earth. Then in theory the planes that are flying there would be no time dilation. The Earth's rotation is decelerating b/c of the pull from the moon, but if it wasn't we couldn't say the Earth was rotating correct? I think now that I slept on it, it's making a bit more sense. Just have to wait for the math to catch up.

This is what was confusing me. If I was standing on Earth & two people walked 2km from me (on East & one West) at the same speeds. I shouldn't be able to tell the time dilation even with the most accurate equipement, right (b/c everything is in uniform motion)? But, if I was in space orbiting the planet, one would have time dilation or do they both have the dilation in both reference frames? That is what is confusing me.
 
kuahji said:
I thought there could be no abosulte at rest reference frames... You could say the universe is rotating around the Earth.





Basically, I thought it didn't matter if the intial reference frame was on Earth. Because in theory you could say the Earth is moving around the Sun, & the sun around a black hole (in theory).



I'm not at that level yet to understand the math. I'm sure when I catch up the ideas will click better. I just thought from what I read you could say the Earth is standing still & the universe is rotating around the Earth. Then in theory the planes that are flying there would be no time dilation. The Earth's rotation is decelerating b/c of the pull from the moon, but if it wasn't we couldn't say the Earth was rotating correct? I think now that I slept on it, it's making a bit more sense. Just have to wait for the math to catch up.

This is what was confusing me. If I was standing on Earth & two people walked 2km from me (on East & one West) at the same speeds. I shouldn't be able to tell the time dilation even with the most accurate equipement, right (b/c everything is in uniform motion)? But, if I was in space orbiting the planet, one would have time dilation or do they both have the dilation in both reference frames? That is what is confusing me.

Try reading this:

http://www.bartleby.com/173/23.html
 
kuahji said:
I'm not at that level yet to understand the math. I'm sure when I catch up the ideas will click better. I just thought from what I read you could say the Earth is standing still & the universe is rotating around the Earth. Then in theory the planes that are flying there would be no time dilation.

Basically, the simple answer to your problem is that rotation is absolute. You can tell by a variety of experiments, including a ring laser gyro, that the Earth is rotating, without reference to any other object.

So it is false to say that you can think of the Earth as standing still and the []universe is rotating about it.

It is correct to say that you cannot know what velocity the Earth has without reference to some other object. The same cannot be said for rotation, however.

This is often sumarized by saying that rotation is absolute, but velocity is relative.
 
Last edited:
Thanks for all the help. It makes sense to me now. :)
 

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