by Markus Schwarz » Wed May 07, 2014 11:48 am
Since we can study the effects of black holes on their surroundings, we are, in a sense, close enough to study it. For instance, we can measure the mass of the black hole at the center of the Milky Way.
But if an experimenter close to the event horizon would send the data via electromagnetic radiation, we would receive this radiation at a larger wavelength. For example, if he were to send a signal in visible light, we might have to use a radio antenna to detect the signal. This also means that, from our far away point of view, his clocks (and all his movements) run at a slower rate than ours. These effects becomes more dramatic the closer the experimenter is to the event horizon. Once he crosses the event horizon, we could no longer receive anything from him.
Since we can study the effects of black holes on their surroundings, we are, in a sense, close enough to study it. For instance, we can measure the mass of the black hole at the center of the Milky Way.
But if an experimenter close to the event horizon would send the data via electromagnetic radiation, we would receive this radiation at a larger wavelength. For example, if he were to send a signal in visible light, we might have to use a radio antenna to detect the signal. This also means that, from our far away point of view, his clocks (and all his movements) run at a slower rate than ours. These effects becomes more dramatic the closer the experimenter is to the event horizon. Once he crosses the event horizon, we could no longer receive anything from him.