Event horizon
The best known kind of event horizon is that of black holes - one of the earliest fruits of Einstein's General relativity, due to brilliant work by Karl Schwarzschild in 1916. A black hole's horizon is a boundary in spacetime from which no signal or radiation can come out to affect an external observer. Put in a simpler way: no light, radio waves, or any other kind of radiation emitted from inside the event horizon can ever hope to escape from it, because in that region the black hole's gravitational pull is so strong that not even light (travelling at the craziest possible speed in the whole universe) can overcome it. So the event horizon is what makes the hole, well... black. Incidentally, I would slightly prefer something like "not-even-black hole", but I suspect that this term would not stick ;-)*
Of course, this narrative is not about black holes - the direct observation of the immediate environment of a black hole with angular resolution comparable to the event horizon is one of the Holy Grails of astrophysics - but I felt the need to attempt and clarify a bit what the concept means.
I was at Cala de la Vinyeta in Calella, as in my previous upload, Primeval light. No black holes there, but a pretty unremarkable, middle-aged yellow star some 4.5 billion years old - yet our most precious friend for a whole lot of reasons.
I was fairly sure that the sun was still below the horizon, as my watch suggested; but the cliff enclosing the Eastern end of the cove hid the very point of the horizon from which the Sun would have risen. I perceived that looming bulk of rosy rocks - would-be rosy sand in a handful of centuries - as an event horizon effectively keeping out of my view the focal point of the approaching sunrise. I decided not to mind the thing - who knows, I thought, sometimes one discover unexpected treasures just out of the trodden track... Moreover, I would not waste precious minutes in tentatively looking for another pov - since, I knew, there are further rocks beyond the cliff.
As the radiance beyond the cliff was growing more and more in the cloudless sky, I began to feel thankful to my personal event horizon for shading my camera from the intense glow :-) So I happily took my exposure bracketing to be processed with luminosity masks and went on enjoying my photographic session.
I am not happy with some parts of this shot - mainly the sea - but I like the glorious glow beyond the cliff, hinting to the hidden sunrise without revealing it. This is the common thread of this series from Cala de la Vinyeta.
* Hope that Hawking will forgive my omission of the radiation named after him, which, however, is produced at the event horizon - so effectively endowing black holes with a temperature, if not with colour.
Event horizon
The best known kind of event horizon is that of black holes - one of the earliest fruits of Einstein's General relativity, due to brilliant work by Karl Schwarzschild in 1916. A black hole's horizon is a boundary in spacetime from which no signal or radiation can come out to affect an external observer. Put in a simpler way: no light, radio waves, or any other kind of radiation emitted from inside the event horizon can ever hope to escape from it, because in that region the black hole's gravitational pull is so strong that not even light (travelling at the craziest possible speed in the whole universe) can overcome it. So the event horizon is what makes the hole, well... black. Incidentally, I would slightly prefer something like "not-even-black hole", but I suspect that this term would not stick ;-)*
Of course, this narrative is not about black holes - the direct observation of the immediate environment of a black hole with angular resolution comparable to the event horizon is one of the Holy Grails of astrophysics - but I felt the need to attempt and clarify a bit what the concept means.
I was at Cala de la Vinyeta in Calella, as in my previous upload, Primeval light. No black holes there, but a pretty unremarkable, middle-aged yellow star some 4.5 billion years old - yet our most precious friend for a whole lot of reasons.
I was fairly sure that the sun was still below the horizon, as my watch suggested; but the cliff enclosing the Eastern end of the cove hid the very point of the horizon from which the Sun would have risen. I perceived that looming bulk of rosy rocks - would-be rosy sand in a handful of centuries - as an event horizon effectively keeping out of my view the focal point of the approaching sunrise. I decided not to mind the thing - who knows, I thought, sometimes one discover unexpected treasures just out of the trodden track... Moreover, I would not waste precious minutes in tentatively looking for another pov - since, I knew, there are further rocks beyond the cliff.
As the radiance beyond the cliff was growing more and more in the cloudless sky, I began to feel thankful to my personal event horizon for shading my camera from the intense glow :-) So I happily took my exposure bracketing to be processed with luminosity masks and went on enjoying my photographic session.
I am not happy with some parts of this shot - mainly the sea - but I like the glorious glow beyond the cliff, hinting to the hidden sunrise without revealing it. This is the common thread of this series from Cala de la Vinyeta.
* Hope that Hawking will forgive my omission of the radiation named after him, which, however, is produced at the event horizon - so effectively endowing black holes with a temperature, if not with colour.