How does a photon's event horizon look like?

[EnumaElish]

http://upload.wikimedia.org/wikipedia/commons/1/1d/Event-horizon-particle.svg

Would there still be a t axis? Would the yellow cone get squished (become one-dimensional) and stretched over the x axis?

Or would it stretch to infinity along the t axis and spread over the entire (x,t) plane?

 

[pervect]

I don't understand the question. Are you perhaps interested in the Rindler horizon experienced by an accelerated observer? (Sorry if this is NOT what you're interested in, but I'm having difficulty in interpreting your question).

 

[EnumaElish]

I assumed that the shape of the event cone would depend on the velocity with which point E is traveling along the t axis. Is that not right?

 

[chroot]

I don't understand the question either. "Event horizon" of a photon? "Event cone?"

- Warren

 

[DaveC426913]

Isn't he showing a Minkowski diagram?

 

[EnumaElish]

I don't understand the question either. "Event horizon" of a photon? "Event cone?"

- Warren

Isn't he showing a Minkowski diagram?

pervect & Warren, thank you for your responses and patience with a non-physicist. Your reply prompted me to take another look at the Wikipedia diagram.

BTW, I noticed that the first link in my OP has become nonfunctional. The new link is: http://upload.wikimedia.org/wikipedia/commons/1/1d/Event-horizon-particle.svgIf you click on it you will see the diagram represented as a spacetime diagram on the Wikipedia page entitled "event horizon."

The caption applicable to this diagram (click on: http://en.wikipedia.org/wiki/Event_horizon) reads: "event E [] is outside the particle [P]'s event horizon."

My questions:
1. Can anyone see the diagram, or is there a broken link?

If you can see the diagram:

2. Which object on the diagram represents P's event horizon?
a. Does the the red curve represent P's event horizon?
b. Do the boundaries of the hourglass-shaped yellow area represent P's event horizon?
c. Does the entirety of the hourglass-shaped yellow area represent P's event horizon?
d. Other: ______ (please specify).

3. What does the entirety of the hourglass-shaped yellow area represent?

4. What do the boundaries of the hourglass-shaped yellow area represent?

5. The Wiki article states "As the particle [P] accelerates, it approaches, but never reaches, the speed of light with respect to its original reference frame. On the spacetime diagram, its path is a hyperbola, which asymptotically approaches a 45 degree line (the path of a light ray)."
5.1. Would this diagram be different if the particle P was traveling at the speed of light?
5.2 How would it be different?
a. Would the red curve be different? How?
b. Do the boundaries of the yellow area be different; how?

Let me know if you need additional information or explanation about any of the questions above and I'll try my best to provide it.

 

[EnumaElish]

Partly due to a lack of responses on the PF, I put the question to Cornell University's "Curious? Ask an Astronomer!" website, and I got an answer in about a week. I decided to post it here for general information and any reactions from the community.

It says (with reference to the Minkoswki diagram on the Wiki page "Event Horizon"):

If event P was the emission of a photon, then the photon's trajectory would appear as a straight line with slope 1 or -1 in the Minkowski diagram (the same as the boundaries of the light cone). The photon could leave event P traveling in the -x direction, in which case it would intersect the light cone, or in the +x direction, in which case it would travel parallel to the right boundary of the light cone for all time.

Admittedly this answers a different question than my original, which I can best state as "If Minskowski was a photon, would there be a diagram? How would it look?" So my original question did evolve under this thread, hopefully for the better.

[Further edit (now this is beginning to look like a blog): Rarely the one to give up, I put my original question to the exceedingly helpful staff of Cornell's Ask An Astronomer website. Their quick response was:

I think I understand your question. The axes of a Minkowski diagram correspond to a particular reference frame. You are curious about what the Minkowski diagram would look like if we were in the frame of an object moving at the speed of light (a photon).

The angle between the time and space axes is 0 degrees if the reference frame is traveling at the speed of light, and so the diagram collapses. So your intuition is good: there would not be a "t" dimension because, in fact, there would be no diagram at all.

Excellent website & great staff, Ezra!]