Mass and Energy Conservation in Relativistic Frames

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

Discussion Overview

The discussion revolves around the conservation of mass and energy in relativistic frames, particularly focusing on the behavior of an electron emitting a photon and the implications of different reference frames. It explores theoretical aspects of relativistic physics, including the effects of acceleration and non-inertial frames.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant observes that from the Earth frame, an electron losing a photon appears to slow down, while in a frame moving with the electron, it seems to gain speed, raising questions about the conservation of mass and energy.
  • Another participant asserts that a single free electron cannot emit a single photon, suggesting a limitation in the scenario presented.
  • A participant introduces the idea of an oscillating electron in an alternating electric field, questioning whether it would emit photons and feel acceleration in a non-gravitational field.
  • It is noted that a stationary accelerometer in the oscillating electron's rest frame would detect oscillating acceleration, indicating a non-inertial frame and the electron's experience of acceleration.
  • A participant proposes a scenario where an electron and neutron are moving in the direction of an electric field, questioning whether the electron gains energy while appearing to slow down relative to Earth.
  • Another participant prompts consideration of the conservation of four-momentum as a framework for understanding the conservation of energy and momentum in this context.

Areas of Agreement / Disagreement

Participants express differing views on the conditions under which an electron can emit a photon and the implications of various reference frames. The discussion remains unresolved, with multiple competing perspectives on the conservation of mass and energy in relativistic contexts.

Contextual Notes

There are limitations regarding the assumptions made about the electron's state (free vs. oscillating) and the implications of non-inertial frames. The discussion does not resolve the mathematical steps involved in the conservation laws being debated.

ankitpandey
Messages
32
Reaction score
0
watching from Earth frame, i see an electron lose a photon and get slower. but if i consider a frame still moving with initial velocity of electron, what do i see? the electron looses a photon,but moves faster. hence its relativistic mass is also greater than rest mass.total energy has increased in both ways. how is sum of mass and energy conserved here?
 
Physics news on Phys.org
Bravo, you have just shown a single free electron cannot emit a single photon.
 
What if it is not free but oscillating due to an alternating electrical field? Does it still see itself in freefall, emitting photons for no reason? or does it "feel" itself accelerating since the field is not gravitational?
 
A stationary accelerometer in the oscillating electron's rest frame would register an oscillating acceleration, so you know that the frame is non-inertial and therefore the electron would "feel" itself accelerating.

To the OP: you may want to look into the conservation of four-momentum, which encapsulates the conservation of energy and conservation of momentum in one nice convenient Lorentz-invariant package.
 
well then let us assume electron and neutron moving in direction of electric field.then, with respect to nuetron, is electron gaining energy when it is actually becoming slower relative to earth?
 
What does conservation of the four-momentum tell you?
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 87 ·
3
Replies
87
Views
6K
  • · Replies 102 ·
4
Replies
102
Views
7K
  • · Replies 55 ·
2
Replies
55
Views
6K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 11 ·
Replies
11
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K