Why does only one object feel accelerated?

  • Context: Graduate 
  • Thread starter Thread starter Ascenxion
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around the question of why only one object feels accelerated in the context of general relativity. Participants explore the implications of this question, particularly in relation to forces, frames of reference, and the distinctions between inertial and non-inertial frames. The scope includes theoretical considerations and conceptual clarifications related to general relativity and special relativity.

Discussion Character

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

Main Points Raised

  • Some participants question the meaning of the phrase "only one object feels accelerated," seeking clarification on which object is being referred to.
  • One participant references the historical context of the question, linking it to Einstein's realization that forces felt by objects undergoing constant proper acceleration are indistinguishable from those in a gravitational field, which is foundational to general relativity.
  • Another participant notes that in special relativity, only inertial frames of reference are considered equivalent, while general relativity expands this to include all frames, even accelerated ones.
  • One participant expresses uncertainty about the term "equivalent frames of reference" in the context of general relativity, suggesting that while GR redefines inertial and accelerated frames, it does not make them equivalent in terms of physical laws.

Areas of Agreement / Disagreement

Participants express differing interpretations of the question and its implications, indicating that multiple competing views remain regarding the nature of acceleration and frames of reference in general relativity and special relativity. The discussion does not reach a consensus.

Contextual Notes

Limitations include potential misunderstandings of the terminology used, such as "equivalent frames of reference," and the need for further clarification on the distinctions between inertial and non-inertial frames in the context of gravitational fields.

Ascenxion
Messages
18
Reaction score
0
In terms of general relativity, what does this question mean?

Thanks.
 
Physics news on Phys.org
Ascenxion said:
In terms of general relativity, what does this question mean?

Thanks.

Does it mean "why does an object feel a force acting on it"?
 
One object? Which object? :confused:
 
Well, I found this question in the http://en.wikipedia.org/wiki/Acceleration" topic in Wikipedia, and I was confused about its meaning.

After completing his theory of special relativity, Albert Einstein realized that forces felt by objects undergoing constant proper acceleration are indistinguishable from those in a gravitational field. This was the basis for his development of general relativity, a relativistic theory of gravity. This is also the basis for the popular twin paradox, which asks why one twin ages less when moving away from his sibling at near light-speed and then returning, since the non-aging twin can say that it is the other twin that was moving. General relativity solved the "why does only one object feel accelerated?" problem which had plagued philosophers and scientists since Newton's time (and caused Newton to endorse absolute space). In special relativity, only inertial frames of reference (non-accelerated frames) can be used and are equivalent; general relativity considers all frames, even accelerated ones, to be equivalent. (The path from these considerations to the full theory of general relativity is traced in the introduction to general relativity.)

Thanks.
 
Last edited by a moderator:
Wikipedia said:
In special relativity, only inertial frames of reference (non-accelerated frames) can be used and are equivalent; general relativity considers all frames, even accelerated ones, to be equivalent.
I don't know what they mean by "equivalent frames of reference", but in GR still only inertial frames have the same physical laws: local experiments give the same results in all of them. The new thing in GR is that free falling frames in a small region of a gravitational field are considered inertial too, so you can use SR there.

So GR is not making accelerated frames equivalent to inertial ones, but it redefines what an inertial vs. accelerated frame is, regarding gravitational fields.
 

Similar threads

Undergrad Does the metric in general relativity depend only on position because of the equivalence principle?
  • · Replies 16 ·
Replies
16
Views
2K
High School How quickly does the Earth feel the effects of a halved Sun's mass?
  • · Replies 38 ·
2
Replies
38
Views
3K
Graduate Looking for linear frame dragging formula
  • · Replies 3 ·
Replies
3
Views
1K
High School Rotating disc: tidal relativity across surface of disc
  • · Replies 14 ·
Replies
14
Views
1K
Undergrad Why does general relativity break down at high energies?
  • · Replies 8 ·
Replies
8
Views
1K
Graduate Different time coordinates due to different velocities
  • · Replies 4 ·
Replies
4
Views
1K
Graduate Why is the Principle of Equivalence Necessary for GTR?
  • · Replies 9 ·
Replies
9
Views
2K
Graduate Weyl tensor and coordinate acceleration
  • · Replies 12 ·
Replies
12
Views
3K
Undergrad Is momentum conserved as a body falls through a gravitational field?
  • · Replies 35 ·
2
Replies
35
Views
3K
Undergrad What Happens When an Object Accelerating Away from a Black Hole Stops?
  • · Replies 35 ·
2
Replies
35
Views
5K