There are as many optical or 'event' horizons (radii from point of observation to event horizon parameter) as there are locations in space.
There seems to be a lot of misunderstandings about this.
The wielder of a flashlight anywhere in space is moving at the speed of light relative to surroundings.
The flashlight beam is projected at the speed of light, no matter where the light beam is projected from.
The speed of light is relative to the source from which it originates.
Any questions, contentions or further qualifications of this submission are invited.
Best regards,
- RP
(George Berkeley, 1710) ... lay the beginning in a distinct explication of what is meant by thing, reality, existence: for in vain shall we dispute concerning the real existence of things, or pretend to any knowledge thereof, so long as we have not fixed the meaning of those words.
"All things come out of the one and the one out of all things." - Heraclitus "Reality is an illusion - albeit a persistent one." - Einstein "Particles give me a headache." - Ibid
There are as many optical or 'event' horizons (radii from point of observation to event horizon parameter) as there are locations in space. There seems to be a lot of misunderstandings about this.
What is an event horizon. There are 3 horizons ... not counting our cosmic horizon.
The Absolute horizon, the Event horizon and the Apparent horizon.
Of these three the absolute and event seem to be similar, but what is the apparent?
Quote:
Originally Posted by From the WIKI
The notion of an apparent horizon begins with the notion of a trapped null surface. We take a (compact, orientable,
spacelike) surface, and find its outward pointing normal vectors. The basic picture to think of here is a ball with
pins sticking out of it; the pins are the normal vectors.
Now we look at light rays that are directed outward, along these normal vectors. The rays will either be diverging
(the usual case one would expect) or converging.
Intuitively, if the light rays are converging, this means that the light is moving backwards inside of the ball. If all the rays around the entire surface are converging, we say that
there is a trapped null surface.
We can take the set of all such trapped surfaces. If we are thinking in terms of a simple Schwarzschild black hole, these surfaces will fill up the black hole. The apparent horizon is then defined as the boundary of these surfaces
— essentially, it is the outermost surface of the black hole, in this sense. Note, however, that a black hole is defined with respect to the event horizon, which is not always the same as the apparent horizon.
How can Light waves that are directed outwards be moving 'backwards' inside the ball ?? I understand how the light waves are diverging see italics above, but can't 'picture' the converging. Does anybody understand this and can you elucidate it ?
Quote:
Originally Posted by RascalPuff
The wielder of a flashlight anywhere in space is moving at the speed of light relative to surroundings.
Don't you mean the beams from the flashlight are moving at the speed of light ?
Quote:
Originally Posted by RascalPuff
The flashlight beam is projected at the speed of light, no matter where the light beam is projected from.
Gottcha ... LOL
Quote:
Originally Posted by RascalPuff
The speed of light is relative to the source from which it originates.
What is this saying ... isn't it the same for all observers ?
Quote:
Originally Posted by RascalPuff
Any questions, contentions or further qualifications of this submission are invited.
Please explain the different horizons, if not you Rascal, then anyone ?? Neutralino ??
cool bananas ... greg
'Blondie says I must hate all Brunettes. I'll try, but if I can't ... I'll love them both' ... graffiti on Tavern wall, Pompeii, circa AD 70.
Hey Mr. Neutralino: Might you proffer your expertise in these issues? Greg has introduced some factors that I hope you can shed some light on, you may form a platform, before I make my next effort. Frankly, Greg has introduced some factors that I'm not familiar with. Anyone wish to share some resolutions on these issues?
Best regards,
- RP
Quote:
Originally Posted by Graybeard
What is an event horizon. There are 3 horizons ... not counting our cosmic horizon.
The Absolute horizon, the Event horizon and the Apparent horizon.
Of these three the absolute and event seem to be similar, but what is the apparent?
Beats me, Greg, I know of only one so called event horizon, and that there are misunderstandings regarding the absolute speed of light, relative to it.
How can Light waves that are directed outwards be moving 'backwards' inside the ball ?? I understand how the light waves are diverging see italics above, but can't 'picture' the converging. Does anybody understand this and can you elucidate it ?
"How can Light waves that are directed outwards be moving 'backwards' inside the ball?"
I don't know of any such backwards moving light relative to the issued horizon, Greg.
Don't you mean the beams from the flashlight are moving at the speed of light ?
Yes.
Gottcha ... LOL
What is this saying ... isn't it the same for all observers ?
In the issue at hand, the relative speed of light is exceeded at the optical horizon, as it relates to the location of the observer. So there's some apparent ambiguity, here.
Please explain the different horizons, if not you Rascal, then anyone ?? Neutralino ??
I know of only one optical/event horizon - that having to do with Hubble's law. The 'absolute' and 'apparent' horizons - I'm not sure how they're differentiated or what that means.
cool bananas ... greg
(George Berkeley, 1710) ... lay the beginning in a distinct explication of what is meant by thing, reality, existence: for in vain shall we dispute concerning the real existence of things, or pretend to any knowledge thereof, so long as we have not fixed the meaning of those words.
"All things come out of the one and the one out of all things." - Heraclitus "Reality is an illusion - albeit a persistent one." - Einstein "Particles give me a headache." - Ibid
Apparent horizons are normally mentioned when discussing the formation of black holes. See here for some brief comments. The important difference between an absolute and an apparent horizon is that just because a particle is outside the apparent horizon at some moment in time, does not mean that it will be able to escape the black hole.
Note that the terms 'event horizon' and 'absolute horizon' are usually synonymous.
I'm on vacation at the moment, so unfortunately can't answer in detail. I'll get onto it in the new year when I'm back home.
~neutralino
If you haven't found something strange during the day, it hasn't been much of a day - John A. Wheeler.
If I am a wielder of a flashlight traveling backward or in the opposite direction of the flash light's pointed direction, and traveling at the speed of light; would the flash light illuminate or emit light when turned on?
If I am a wielder of a flashlight traveling backward or in the opposite direction of the flash light's pointed direction, and traveling at the speed of light; would the flash light illuminate or emit light when turned on?
= MJA
Answer me that one Batman!
Hey MJA, good to hear from you.
Until further authoritative notice, the answer to your question is affirmative.
Flashlights moving at relative speeds of light, both frontwards and backwards, are being wielded all the time, most everywhere flashlights are wielded.
Best regards,
- RP
(George Berkeley, 1710) ... lay the beginning in a distinct explication of what is meant by thing, reality, existence: for in vain shall we dispute concerning the real existence of things, or pretend to any knowledge thereof, so long as we have not fixed the meaning of those words.
"All things come out of the one and the one out of all things." - Heraclitus "Reality is an illusion - albeit a persistent one." - Einstein "Particles give me a headache." - Ibid
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