The Naked Scientists

The Naked Scientists Forum

Author Topic: What radius to a human observer does light fail to give an observation?  (Read 6573 times)

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
I think that if a person was at any reference point in the Universe a human would have a spherical view, this sphere of sight has a radius limit, what is the radius of sight ratio to magnitude of light?
« Last Edit: 09/02/2016 09:52:47 by Thebox »


 

Offline Atomic-S

  • Hero Member
  • *****
  • Posts: 928
  • Thanked: 18 times
    • View Profile
I don't quite understand your question. Are you asking how far away a star can be and still be visually bright enough to be seen with the naked eye?
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
I don't quite understand your question. Are you asking how far away a star can be and still be visually bright enough to be seen with the naked eye?

Yes and no, Imagine you are the star, how far can you see by your own light magnitude?

Then the second part, at what distance does vanishing points play a role?


added - I drew my question for you.




And in quantum weirdness, if you was the sun and there was nothing reflecting light or emitting light, you would observe darkness even though you were emitting light.









« Last Edit: 12/02/2016 10:13:04 by Thebox »
 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4699
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile
"Vanishing point" is an invention of artists, architects and cartographers. It is also a classic road trip film - to my mind the best ever. It has no meaning in physics.

The human eye can probably detect a single photon, though in practice we could not distinguish it from the background "noise" in our brains, so in principle there is no limit to the distance at which you could detect a single source in an otherwise empty universe, provided you can wait long enough.

As for your second point, it's nothing to do with quantum weirdness. On a really clear, dry night you can shine a laser into the sky and not see the beam if it's pointing away from you. 
 
The following users thanked this post: Arnie O'Dell

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
"Vanishing point" is an invention of artists, architects and cartographers. It is also a classic road trip film - to my mind the best ever. It has no meaning in physics.



A vanishing point has no meaning in physics?  I find that very strange when it is a fundamental aspect of relativity.

An object moving away from an observer relative decreases in size , does know one think of this?

''As for your second point, it's nothing to do with quantum weirdness. On a really clear, dry night you can shine a laser into the sky and not see the beam if it's pointing away from you. ''

Why are you changing the natural scenario to observer effect and using a laser?

If you was on the Sun looking away from the sun, and there was no other matter or stars, I assure you that you will observe only darkness.  Your Universe would be has high as you could jump.



 

Offline Colin2B

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1917
  • Thanked: 123 times
    • View Profile
A vanishing point has no meaning in physics?  I find that very strange when it is a fundamental aspect of relativity.
Vanishing point and perspective have no connection to relativity. Is this a New Theory?
 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4699
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile

Why are you changing the natural scenario to observer effect and using a laser?


In order to replace your hypothetical absurdity with a practical experiment that is simple enough for a moron to comprehend. I'm sorry you didn't.
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile

Why are you changing the natural scenario to observer effect and using a laser?


In order to replace your hypothetical absurdity with a practical experiment that is simple enough for a moron to comprehend. I'm sorry you didn't.

A practical experiment that only a moron would presume is anything like the nature of light. A laser is a linearity where as light from a body is isotropic. You would not see a laser beam unless there was a dense medium.

« Last Edit: 13/02/2016 08:10:22 by Thebox »
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
A vanishing point has no meaning in physics?  I find that very strange when it is a fundamental aspect of relativity.
Vanishing point and perspective have no connection to relativity. Is this a New Theory?

Is this  a new theory?  No Colin it is discussing a definition apparently not used in science although it is very relative.

 

Offline Colin2B

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1917
  • Thanked: 123 times
    • View Profile
..... it is discussing a definition apparently not used in science although it is very relative.
Then it is a new theory, or more likely 'that can't be true', so don't discuss it here
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
..... it is discussing a definition apparently not used in science although it is very relative.
Then it is a new theory, or more likely 'that can't be true', so don't discuss it here

Huh?  how is talking about perspective view, vanishing points, and objects relatively look smaller at a distance a new theory?

You obviously call vanishing points and perspective view something different.



« Last Edit: 13/02/2016 09:16:32 by Thebox »
 

Offline Colin2B

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1917
  • Thanked: 123 times
    • View Profile

Huh?  how is talking about perspective view, vanishing points, and objects relatively look smaller at a distance a new theory?
It is if you try to relate it to relativity, which you were doing.
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile

Huh?  how is talking about perspective view, vanishing points, and objects relatively look smaller at a distance a new theory?
It is if you try to relate it to relativity, which you were doing.

I am not trying to relate it to relativity, it is an axiom that it is related to relativity, things at a distance relative to the observer look smaller than they actually are.

Things that move away relatively to the observer decrease in visual size.

I am not relating it, it is already related, I miss your point.

 

Offline Colin2B

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1917
  • Thanked: 123 times
    • View Profile
... it is an axiom that it is related to relativity,
It is not an axiom, and yes you miss my point.
This is not the thread to discuss your theory of relativity and vanishing points.
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
What radius to a human observer does light fail to give an observation?
What is the point of me asking a question if you are not willing to discuss the question?

What radius to a human observer does light fail to give an observation is the question, now if light has failed to give an observation, the objects has vanished relative to the observation, so at that very point, ''the vanishing point'', is very related to the question and not a theory.
 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4699
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile
The question was answered in reply #3. What is the point of asking a question if you intend to disagree with the answer?
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
The question was answered in reply #3. What is the point of asking a question if you intend to disagree with the answer?

The question I asked was not answered, I will rephrase,

What is the radius from a light source where matter fails to reflect enough light to observe the object?

 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4699
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile
The answer remains the same:

In principle there is no limit to the distance at which you could detect a single source in an otherwise empty universe, provided you can wait long enough.

From the observer's point of view there is no difference between a primary source and a reflector.
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
The answer remains the same:

In principle there is no limit to the distance at which you could detect a single source in an otherwise empty universe, provided you can wait long enough.

From the observer's point of view there is no difference between a primary source and a reflector.

HUh ? I thought light diminishes at a distance in compliance with the inverse square law?

If the light diminishes then surely any  matter receiving the diminished light reflects a lesser magnitude?

If the boundary  is limitless, why do I need a more powerful flash-light to see further?

« Last Edit: 14/02/2016 16:11:52 by Thebox »
 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4699
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile
HUh ? I thought light diminishes at a distance in compliance with the inverse square law?


Exactly. And 1/r2 > 0 for all values of r, so there will always be a photon if you wait long enough.

The devil is in that last detail - if you wait long enough. As I pointed out way back in this discussion, yopu won't be able to distinguish a single photon from noise in the real world, so you need a bigger flashlight to see objects further away in the presence of air, dust, starlight, and the thermal noise in your brain, but you could use an integrating image amplifier (your mobile phone camera set to "night" mode) or a photomultiplier attached to a telescope instead.     
« Last Edit: 14/02/2016 17:52:47 by alancalverd »
 

Offline Ophiolite

  • Hero Member
  • *****
  • Posts: 716
  • Thanked: 6 times
    • View Profile
I am not trying to relate it to relativity, it is an axiom that it is related to relativity, things at a distance relative to the observer look smaller than they actually are.

Things that move away relatively to the observer decrease in visual size.
I am not relating it, it is already related, I miss your point.
The point is that when you say relativity on a science forum it is understood that you are referring to Einstein's theories of Special and General Relativity unless you explicitly state otherwise. Ignoring this basic point is at best foolish and at worst deliberately obtuse, hence rude.
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
I am not trying to relate it to relativity, it is an axiom that it is related to relativity, things at a distance relative to the observer look smaller than they actually are.

Things that move away relatively to the observer decrease in visual size.
I am not relating it, it is already related, I miss your point.
The point is that when you say relativity on a science forum it is understood that you are referring to Einstein's theories of Special and General Relativity unless you explicitly state otherwise. Ignoring this basic point is at best foolish and at worst deliberately obtuse, hence rude.

Did I even say relativity?  I said relatively

''relatively
ˈrɛlətɪvli/Submit
adverb
in relation, comparison, or proportion to something else.
"they were very poor, but, relatively speaking, they had been lucky"
regarded in comparison with something else rather than absolutely; quite.''

added- yes I did say relativity but I mean the relativity of something.
« Last Edit: 14/02/2016 20:44:44 by Thebox »
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
HUh ? I thought light diminishes at a distance in compliance with the inverse square law?


Exactly. And 1/r2 > 0 for all values of r, so there will always be a photon if you wait long enough.

The devil is in that last detail - if you wait long enough. As I pointed out way back in this discussion, yopu won't be able to distinguish a single photon from noise in the real world, so you need a bigger flashlight to see objects further away in the presence of air, dust, starlight, and the thermal noise in your brain, but you could use an integrating image amplifier (your mobile phone camera set to "night" mode) or a photomultiplier attached to a telescope instead.   


You always elude the actually question and reply with seemingly irrelevant  answers to the actual question.
« Last Edit: 14/02/2016 21:36:33 by Thebox »
 

Offline Arnie O'Dell

  • First timers
  • *
  • Posts: 9
  • Thanked: 1 times
    • View Profile
Are you talking about light cones?
 

Offline Thebox

  • Neilep Level Member
  • ******
  • Posts: 3154
  • Thanked: 44 times
    • View Profile
Are you talking about light cones?

I am asking about light ''spheres'' that diminish at a distance from an ''inside'' observers perspective.

Putting the question a different way.

Hello science , I go night fishing, which means I go fishing in the dark, I use a head lamp, however my vision is limited to the wattage of the bulb, I can only observe so far then all things fade out , I can not see  the other side of the lake, I can not see my friend who is on the next fishing spot along the bank side, he assures  me though he can see me and my head lamp, I can see my rods reflecting light, why can't I see my friend reflecting light, why does this happen?

« Last Edit: 14/02/2016 23:52:22 by Thebox »
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums