How can you see light that is traveling away from the observer?

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Light can be seen when it hits a surface because the surface scatters some of the light back to the observer's eyes. In a dark environment, such as a salt flat, a beam from a torch or laser can illuminate the ground, allowing the observer to see the point of impact due to this scattering effect. If there are no particles or surfaces to reflect the light, such as in a vacuum, the light would not be visible to the observer. The discussion emphasizes that without scattering particles like dust or water vapor, light traveling away from the observer cannot be seen. Therefore, the visibility of light depends on the presence of surfaces that can reflect some of the light back.
  • #31
Intersesting how people seem so obsessed with trying to prove new ideas wrong, and even expect that somethinng that has taken years to figure out, they can find the solution to without even needing to think- such genius.
 
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  • #32
Originally posted by simon
Intersesting how people seem so obsessed with trying to prove new ideas wrong, and even expect that somethinng that has taken years to figure out, they can find the solution to without even needing to think- such genius.

First off i did commend you for looking for a reason to discard the theory. Secondly you're idea makes the wrong assumption that the salt flat is a 2 dimensional planar surface. its not. Its a fractal surface simliar to talus slope. Read Chaos by Gleick for more info on that, also see the the famous paper on the length of the british coastline ( i think it was mandelbrot). The same principles apply to the salt flat, and as a result the light does not strike the surface at the angle you measure. The average angle opf reflection can be calculated based upon the fractal dimension of the flat (for a talus slope it is 2.7, so i imagine the flat would be close to that)but it suffices to say that rocketcity's calculations demonstrate the point adequately. The factal structure is why the light reflects like that. You need to stop thinking about a quantum phenomenon as existing at the human level. At the human level photons are insignificant, you have to examine a phenonmenon like light and light scattering at the quantum level at which it occurs in which case the fractal nature of the salt flat becomes clearly important.
 
  • #33
franznietzsche,

It's not at all necessary to characterize the salt flat as having any fractal structure.

It's very simple: salt grains are three dimensional crystals. Some of their faces will happen to be oriented properly to reflect incoming light 180 degrees, directly back to its source.

- Warren
 
  • #34
Originally posted by simon
Intersesting how people seem so obsessed with trying to prove new ideas wrong, and even expect that somethinng that has taken years to figure out, they can find the solution to without even needing to think- such genius.
That isn't at all what we're doing - this is not a new situation for existing laws of physics. It is (has already been) quite easily explained.
...well so much for being patient with him.
3 pages is enough. Time for tough love.

Plus, I'm sick and therefore irritable today.
 
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  • #35
It would seem Simon got the best of the two Mentors, for three pages of this crock is every bit as much the fault of the response. The best return for this thread would have been no response at all. Surely you could have left poor Simon in the dark on that desert with a salty taste in his mouth, but nooooooooooooooooooo! You had to drag yerselves down to that desert, and save him, or eat him alive ... whichever comes first :-). This in my opinion ... puts you in the same class as Simon, where clearly he got the best of you. :wink:
 
  • #36
UltraPi1,

Open communication is the only way for us to evolve. If current theories are ALL correct, why hasn't unification happened? Something must change, perhaps only perspective. The mentors on this forum do not need their cage rattled so as to develop disdain for people who ask questions, however ignorant they might seem. The conversations that degrade into angry exchanges already have them at arms length. How much further until their existence is pointless?

Only a fool critisizes someone for helping others.


LPF
 
  • #37
Originally posted by UltraPi1
It would seem Simon got the best of the two Mentors, for three pages of this crock is every bit as much the fault of the response. The best return for this thread would have been no response at all. Surely you could have left poor Simon in the dark on that desert with a salty taste in his mouth, but nooooooooooooooooooo! You had to drag yerselves down to that desert, and save him, or eat him alive ... whichever comes first :-). This in my opinion ... puts you in the same class as Simon, where clearly he got the best of you. :wink:



and i thought i was an elitist...
 
  • #38
I am not sure if I got Simon's question right (it is a little difficult to discern exactly what the question is) but if I did, you seem to misunderstand what he is asking.

He isn't asking why he can see the dot.
He is asking why he can see the dot the same regardless of what angle the light reflects off the surface and what angle he views it at.
Since the surface refects the light in a scattered pattern, his contention is that as the angle of approach, and the angle of the observer changes, so should the intensity of the reflected spot of light.

Is this right, Simon?
(See the poorly drawn attached image. By the way, that is a three-legged stool that guy on the right is standing on.)

It seems that Simon is saying that all 5 observers in this picture will see both reflected dots (assuming identical lasers) as not only having the same intensity and shape, but all 5 observers will see the dots as the same intensity and shape with respect to each other's point of view.
In other words, observer 1 will see two identical dots that are identical to the two dots that observers 2-5 will see.

What Simon is claiming is that since the dots are being reflected in many different directions by the intricate sand surface, each observer should have a different number of photons aimed directly at his/her eyes so each observer's impression of the intensity and shape of the dots (s)he sees should vary from the next observer's (of course, not taking into account physical differences in each observer, as if eack of those five positions were all specifically Simon himself).

Is that what you were trying to ask, Simon?

Click here for image

(edited to add the URL, because I couldn't see my attached image)
 

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  • #39
Where's my attached image?

I guess I will have to upload it and post a link.

Edited to say that I posted a link to the image in the above post.
 
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  • #40
Originally posted by 8LPF16
If current theories are ALL correct, why hasn't unification happened? Something must change, perhaps only perspective. The mentors on this forum do not need their cage rattled so as to develop disdain for people who ask questions, however ignorant they might seem.
[maybe out of context, but important, nonetheless] The question here of course is: how much? How much do our current theories need to change to unify them? Important question, clearly.

Though many on the TD forum would like us to believe the changes will be massive and sweeping, it just can't be that way. There may yet be some profound change in our understanding of the underlying mechanisms, but that will likely change very little about how the current theories work - because they do work. They work extremely well. Any new theory will obviously need to agree with the existing ones and the massive body of evidence that supports them.
 
  • #41
He is asking why he can see the dot the same regardless of what angle the light reflects off the surface and what angle he views it at.
Well, he doesn't. If he did, interior decorating using light would be useless. In reality, no material scatters light in a perfectly uniform fashion. Hence, for example, photographers can use white pieces of paper to provide soft lighting for a scene. And increasing the distance does diminish the intensity of the light, or reflected light. This effect is not very noticable on the small scales he talks about. The roughness of the surface simply makes it hard to notice. The shape of the dot also does change, but the small size of the dot makes it harder to see.

Then we somehow came to the classic symptoms of paranoic-narcissitic-arrogant-crackpotism.
 
  • #42
Then we somehow came to the classic symptoms of paranoic-narcissitic-arrogant-crackpotism

Isn't that contagious?

LPF
 
  • #43
Originally posted by FZ+
Well, he doesn't. If he did, interior decorating using light would be useless. In reality, no material scatters light in a perfectly uniform fashion.

Oh, I know.
I am not arguing that at all.
I know he was wrong in his basic assumptions.
I am just saying that I think that was his point/question, and he seemed to be getting agitated because people were not answering that question.

If he hasn't left for good, maybe he can clarify that.

Are you around?
 

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