In this answer https://physics.stackexchange.com/a/92833/36977 John said that acceleration is not relative in the general theory of relativity.

But as we all know, accelerating charges emit electromagnetic waves. So consider me and a charged body. Suppose acceleration is relative. Then if I accelerate, from my reference frame the charged body is accelerating, and thus would emit electromagnetic radiation. But if the charged body and I are both at rest and then start accelerating with the same acceleration $a$ in the same direction relative then, from my perspective it won't be accelerating since it's acceleration is the same as mine. But the charged body is accelerating. So it must emit radiation. But, as I understand it, that means I shouldn't see that radiation because from my perspective it is at rest.

Is there a contradiction here?

  • 2
    $\begingroup$ Quick correction: I said acceleration is absolute in special relativity but not in general relativity. $\endgroup$ Commented Jan 8, 2014 at 19:58
  • $\begingroup$ So ok, by special relativity a charged body wont emit electromagnetic waves so if it is in the same situation as in my case? @JohnRennie $\endgroup$
    – lotofdots
    Commented Jan 8, 2014 at 20:28
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    $\begingroup$ You can feel your own acceleration (the g-force you experience) with an accelerometer. So you can deduce that you are accelerating, and that therefore the charged body must be accelerating as well. $\endgroup$
    – Pulsar
    Commented Jan 9, 2014 at 1:19
  • $\begingroup$ possible duplicate of Does a charged particle accelerating in a gravitational field radiate? $\endgroup$ Commented Jan 9, 2014 at 10:05
  • $\begingroup$ @Pulsar But from my reference frame, the particle wont be accelerating since it wouldn't be moving from my frame of referance $\endgroup$
    – lotofdots
    Commented Jan 9, 2014 at 13:30

1 Answer 1


The problem is that your reference frame is not inertial so you can't apply the physics valid for an inertial system. A charge accelerating with respect to an inertial system radiates according to Maxwell's equations, which are valid for an inertial system. You just can't simply apply Maxwell's equation in a non-inertial frame.


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