I came across a video by Youtube author p-brane which seems to bring up a lot of good points, showing that the diagrams which are routinely paraded as examples for why the sun cannot set do not accurately demonstrate perspective.I'm trying to do this on a tablet, so it might not be too successful!
https://www.youtube.com/watch?v=W0Gx1vD1CRE
"The range of the eye, or diameter of the field of vision, is 110°; consequently this is the largest angle under which an object can be seen. The range of vision is from 110° to 1°. . . . The smallest angle under which an object can be seen is upon an average, for different sights, the sixtieth part of a degree, or one minute in space; so that when an object is removed from the eye 3000 times its own diameter, it will only just be distinguishable; consequently the greatest distance at which we can behold an object like a shilling of an inch in diameter, is 3000 inches or 250 feet."
The above may be called the law of perspective. It may be given in more formal language, as the following:. when any object or any part thereof is so far removed that its greatest diameter subtends at the eye of the observer, an angle of one minute or less of a degree, it is no longer visible.
Now in the video at about 5:00 he states "notice how all the lines converge the same point, the vanishing point."
Now the height of these lines at the observer is 5,000 km (near enough to 3,000 miles). According to "Parallax" this vanishing point is at 3,000 times the size of the object, which is 5,000 km. So sure the video is largely quite correct, but just draws absolutely the wrong conclusion by taking the vanishing point at about 10,000 km (6,000 miles).I'll let you take it from there!
I came across a video by Youtube author p-brane which seems to bring up a lot of good points, showing that the diagrams which are routinely paraded as examples for why the sun cannot set do not accurately demonstrate perspective.
Yes, the sun shrinks to perspective. The size of the sun at sunset is another topic entirely, and is answered in Earth Not a Globe and on the Magnification of the Sun at Sunset page in the Wiki (http://wiki.tfes.org/Magnification_of_the_Sun_at_Sunset).I was not talking about the sun's size - I was applying Parallax's "Law of Perspective" to the apparent height of the sun.
Magnification and Shrinkingmy highlight.
Q: If the sun is disappearing to perspective, shouldn't it get smaller as it recedes?
A: The sun remains the same size as it recedes into the distance due to a known magnification effect caused by the intense rays of light passing through the strata of the atmolayer.
(http://i1075.photobucket.com/albums/w433/RabDownunder/03-Setting%20Sun_zpsjh3haemo.jpg) | (http://i1075.photobucket.com/albums/w433/RabDownunder/26%20-%20Sunset%20to%20North_zpsytujy348.jpg) |
I was not talking about the sun's size - I was applying Parallax's "Law of Perspective" to the apparent height of the sun.
Yes, I have seenQuoteMagnification and Shrinkingmy highlight.
Q: If the sun is disappearing to perspective, shouldn't it get smaller as it recedes?
A: The sun remains the same size as it recedes into the distance due to a known magnification effect caused by the intense rays of light passing through the strata of the atmolayer.
I have massive problems with this:
- The sun's apparent size stays exactly the same right through the day, not just near the horizon.
- The sun's apparent size is exactly the same at all latitudes, right from the equator when overhead to near the poles when it is on the horizon.
If the sun was magnified by the "glare effect" it would not appear as a sharp circular shape on the horizon, as it often does when the air is very clear.
I came across a video by Youtube author p-brane which seems to bring up a lot of good points, showing that the diagrams which are routinely paraded as examples for why the sun cannot set do not accurately demonstrate perspective.This can easily be tested with a protractor, a string, tape measure, an object of sufficient height, and something to tie the string off to.
https://www.youtube.com/watch?v=W0Gx1vD1CRE
No, the headlights of the cars further away are pointed more directly at the low resolution camera. As they get closer, the headlights start to point away. Headlights always appear as tiny points of light that grow larger the closer they get when viewed head-on.
The headlights of the cars along the highway in the headlight example (http://wiki.tfes.org/Magnification_of_the_Sun_at_Sunset#Headlight_Example) also stay the same size into the distance. They should be little pinpricks of light in the distance.
(http://wiki.tfes.org/images/a/a7/Headlight_example.jpg)
Yes, I quite agree! "The enlargement ratio of a picture enlarged from a projecting light source is exactly the same as the ratio which causes an object to shrink when it recedes into the distance. "I was not talking about the sun's size - I was applying Parallax's "Law of Perspective" to the apparent height of the sun.
You're going to have to rephrase your point, then. I have no idea what you were talking about.QuoteYes, I have seenQuoteMagnification and Shrinkingmy highlight.
Q: If the sun is disappearing to perspective, shouldn't it get smaller as it recedes?
A: The sun remains the same size as it recedes into the distance due to a known magnification effect caused by the intense rays of light passing through the strata of the atmolayer.
I have massive problems with this:
- The sun's apparent size stays exactly the same right through the day, not just near the horizon.
The headlights of the cars along the highway in the headlight example (http://wiki.tfes.org/Magnification_of_the_Sun_at_Sunset#Headlight_Example) also stay the same size into the distance. They should be little pinpricks of light in the distance.
(http://wiki.tfes.org/images/a/a7/Headlight_example.jpg)Quote
- The sun's apparent size is exactly the same at all latitudes, right from the equator when overhead to near the poles when it is on the horizon.
The more distance which allows it to shrink gives it the atmosphere it needs to enlarge.
In fact, the phenomena are the same. Consider a light projector. An image from a projecting source can cover more of a screen's surface area when the projector is further away from the screen because the surface area of the screen has shrunk to perspective. The enlargement ratio of a picture enlarged from a projecting light source is exactly the same as the ratio which causes an object to shrink when it recedes into the distance.
So it is no amazement that the phenomena of light projection and the phenomena of shrinking to perspective can be so tightly correlated.Quote"They should be little pinpricks of light in the distance.", yes, but all we are seeing is the glare in the misty air, see the photos below - no sigh of glare there!
In any case, the sun shows much more glare at midday, especially if seen through haze.
If the sun was magnified by the "glare effect" it would not appear as a sharp circular shape on the horizon, as it often does when the air is very clear.
The sun is not sharp and circular at the horizon. It is often rather hazy and indistinct compared to the noonday sun.
(http://i1075.photobucket.com/albums/w433/RabDownunder/03-Setting%20Sun_zpsjh3haemo.jpg) | (http://i1075.photobucket.com/albums/w433/RabDownunder/26%20-%20Sunset%20to%20North_zpsytujy348.jpg) |
The sun and moon are very hazy when they set. Photographers go to great lengths to capture them at the right moment when they are perfect circles. I encourage you to watch them set sometime.Well, I was the photographer, and went to no particular lengths.
(https://i1.wp.com/autourduciel.blog.lemonde.fr/files/2013/12/2014LeMondeleverPleineLune.jpg)
I came across a video by Youtube author p-brane which seems to bring up a lot of good points,It misses the most important point: the laws of perspective are a consequence of the size and biology of man's retina.
If the sun disappears due to distance, wouldn't you expect it to get smaller and smaller until it finally disappears? That's how literally everything else works. Why make an exception for the sun and moon?
If the sun disappears due to distance, wouldn't you expect it to get smaller and smaller until it finally disappears? That's how literally everything else works. Why make an exception for the sun and moon?
http://wiki.tfes.org/Magnification_of_the_Sun_at_Sunset
I can't believe you are actually sticking to this argument, despite it completely flying in the face of all observation. What happened to the precious Zetetic method, with its emphasis on observation?
I can't believe you are actually sticking to this argument, despite it completely flying in the face of all observation. What happened to the precious Zetetic method, with its emphasis on observation?
An observation was provided:
(http://wiki.tfes.org/images/a/a7/Headlight_example.jpg)
I can't believe you are actually sticking to this argument, despite it completely flying in the face of all observation. What happened to the precious Zetetic method, with its emphasis on observation?
An observation was provided:
(http://wiki.tfes.org/images/a/a7/Headlight_example.jpg)
An observation was provided:Real-world observations prove otherwise. Viewed head-on the entire time they appear tiny and grow larger. As stated already, your picture does not show what you are claiming.
An observation was provided:Real-world observations prove otherwise. Viewed head-on the entire time they appear tiny and grow larger.
Driving at night on a straight stretch with oncoming traffic. I guess you have never done this. You should try it sometime.An observation was provided:Real-world observations prove otherwise. Viewed head-on the entire time they appear tiny and grow larger.
Where is your evidence?
Driving at night on a straight stretch with oncoming traffic. I guess you have never done this. You should try it sometime.An observation was provided:Real-world observations prove otherwise. Viewed head-on the entire time they appear tiny and grow larger.
Where is your evidence?
Driving at night on a straight stretch with oncoming traffic. I guess you have never done this. You should try it sometime.An observation was provided:Real-world observations prove otherwise. Viewed head-on the entire time they appear tiny and grow larger.
Where is your evidence?
I provided evidence. You did not.
you have provided excellent evidence that a directional light source appears brighter when viewed head-on rather than at an angle.
good work. however, this does nothing to support your absurd claim that light sources appear brighter and larger as they recede from an observer.
you have provided excellent evidence that a directional light source appears brighter when viewed head-on rather than at an angle.The entire highway is at an angle to the observer, they are not approaching head on.
If headlights really shrink appropriately into the distance, where are all of the pictures which show headlights as pinpricks in the distance?
(https://d2v9y0dukr6mq2.cloudfront.net/video/thumbnail/Vd3bj2jPe/night-traffic-on-autobahn-night-city-road_vkqxllatl__M0000.jpg)
If headlights really shrink appropriately into the distance, where are all of the pictures which show headlights as pinpricks in the distance?
you have provided excellent evidence that a directional light source appears brighter when viewed head-on rather than at an angle.The entire highway is at an angle to the observer, they are not approaching head on.
I made a simple diagram to explain his point. Car #2 is closer, but the camera isn't being directly illuminated by the headlights. Car #1 is farther, but is directly illuminating the camera.
If headlights really shrink appropriately into the distance, where are all of the pictures which show headlights as pinpricks in the distance?
(https://d2v9y0dukr6mq2.cloudfront.net/video/thumbnail/Vd3bj2jPe/night-traffic-on-autobahn-night-city-road_vkqxllatl__M0000.jpg)
it's genuinely stunning how obtuse you are, tom. this isn't that hard to get.
(http://i.imgur.com/C1jC4qc.png)
I made a simple diagram to explain his point. Car #2 is closer, but the camera isn't being directly illuminated by the headlights. Car #1 is farther, but is directly illuminating the camera.When the sun is visible it is always directly illuminating your eyes. So it is bigger.
The headlights in the back are clearly larger than they should be.
Look at the tail lights. They are all the same size down the highway for as far as the eye can see. In the distance they grow to huge proportions!
That diagram had nothing to do with the sun. It was used to explain why the cars in front look dimmer in the photograph.
Imagine you have 2 flashlights. One is very close, but pointed away from you. The other one is farther away, but pointed directly at you.
Tom Bishop: Wow! the farther flashlight is brighter!!! Lights must get brighter as they get further away!!!
Everyone else: Umm... the closer flashlight isn't even pointed at you. Of course it looks dimmer.
Tom Bishop: But the sun is always pointed at you!! Therefore my point is proven!!
Everyone else: ???/
How large do you think they "should be"? My point is that they do actually get smaller, by a significant amount. 9 pixels -> 2 pixels.
I will concede one point: the headlights appear bigger relative to the cars they are attached to. This is due to glare. When photographing the sun, we can eliminate glare from the equation. See my post in the debate thread (http://forum.tfes.org/index.php?topic=5058.0) for further details.
QuoteLook at the tail lights. They are all the same size down the highway for as far as the eye can see. In the distance they grow to huge proportions!
Those are called break lights. The cars going in the back are going into a turn. Most cars press their breaks when they are about to turn.
The bottom line is that you really need to learn to control outside variables when testing a theory. All these pictures of highways have a lot of outside variables that can influence the result. (And yet they STILL don't support your theory!)
To prove a theory, you need to design an experiment that keeps all variables the same except the one you want to test.
For example, if you want to prove that "lights stay the same size regardless of distance", you need to make sure all variables remain the same except distance.
Experiment: Grab a flashlight. Walk outside. Stick the flashlight on a table/chair/tree/bush at eye level. Make sure it is pointing towards you. Walk backwards. Observe the size of the flashlight at various distances.
I guarantee that the flashlight will not appear to stay the same size. Case closed.
it's genuinely stunning how obtuse you are, tom. this isn't that hard to get.
(http://i.imgur.com/C1jC4qc.png)
The sun doesn't have that problem. Therefore the enlarging effect applies.
I have provided evidence showing that it is possible for a light source to remain the same size as it goes into the distance. Two examples were provided. The lights in the distance are clearly larger than they should be.
The bottom line is that you really need to learn to control outside variables when testing a theory. All these pictures of highways have a lot of outside variables that can influence the result. (And yet they STILL don't support your theory!)
To prove a theory, you need to design an experiment that keeps all variables the same except the one you want to test.
For example, if you want to prove that "lights stay the same size regardless of distance", you need to make sure all variables remain the same except distance.
Experiment: Grab a flashlight. Walk outside. Stick the flashlight on a table/chair/tree/bush at eye level. Make sure it is pointing towards you. Walk backwards. Observe the size of the flashlight at various distances.
I guarantee that the flashlight will not appear to stay the same size. Case closed.
I provided evidence of the odd effect which allows light sources to remain the same size into the distance. We have two pictures which demonstrate the effect. The first picture show headlights that remain the same size, and the second picture shows tail lights that remain the same size. You have not provided any evidence for your position.
The sun doesn't have the problem of unidirectional bulbs.
Whatever you want to call it, it is an effect which magnifies the light.
The headlights in the back are clearly larger than they should be.In the second picture, they still appear smaller in the distance. Does the light from the individual headlights appear a little larger than their actual size? Yes. Do you know how camera exposure affects these kinds of things?
Look at the tail lights. They are all the same size down the highway for as far as the eye can see. In the distance they grow to huge proportions!Nope, those also appear smaller than the taillights closer to the camera. Look closer.
The sun doesn't have that problem. Therefore the enlarging effect applies.Does the sun act like a spotlight, or does it act like (or is) a sphere shining in all directions?
The closest headlights do not show much glare as they are dipped and are considerably below the camera.you have provided excellent evidence that a directional light source appears brighter when viewed head-on rather than at an angle.
good work. however, this does nothing to support your absurd claim that light sources appear brighter and larger as they recede from an observer.
The entire highway is at an angle to the observer, they are not approaching head on.
If headlights really shrink appropriately into the distance, where are all of the pictures which show headlights as pinpricks in the distance?(https://d2v9y0dukr6mq2.cloudfront.net/video/thumbnail/Vd3bj2jPe/night-traffic-on-autobahn-night-city-road_vkqxllatl__M0000.jpg)
(http://www.skyandtelescope.com/wp-content/uploads/Full_Moon_bw_RTF_l.jpg) On Thursday, December 15, 2005, the full Moon will be just about at the most northerly declination it can ever attain. S&T: Rick Fienberg.From: The Highest Full-frontal Overhead (http://www.skyandtelescope.com/astronomy-news/observing-news/the-highest-full-moon-overhead/) | (https://magoism.files.wordpress.com/2014/09/moon-at-night-public-domain.jpg) Moon near horizon from Moon at Night (https://magoism.files.wordpress.com/2014/09/moon-at-night-public-domain.jpg) |