The discussion centers on the observation of accretion around black holes, particularly in relation to the event horizon (EH) and time dilation effects. Participants clarify that while light from objects crossing the EH cannot be observed due to extreme redshift, the accretion disk surrounding the EH remains visible. The accretion disk emits light and is located outside the EH, allowing for the observation of material falling into the black hole, which contributes to its mass over time. The conversation also touches on the complexities of rotating black holes and the formation of jets from the ergosphere.
PREREQUISITESAstronomers, astrophysicists, and students of physics interested in black hole dynamics, accretion processes, and observational techniques in astrophysics.
Is the minimum difference between the times you mention effectively zero? Does the black hole mass matter to any significant degree? Just curious if it's an extended event for the observer or if it's also effectively instantaneous.Nugatory said:However, there is a time in your reference frame such that if you send a radio message to the poor guy falling into the black hole before that time he will be able to to reply to it; but after that time although your message may reach him, he will be unable to reply to it because he will be inside the horizon by the time it reaches him. There is also a later time such that if you don't send your radio message before that later time it will never get to the infaller because he'll have reached the central singularity before the message gets to him.