[Marxism] twinkle twinkle -was America No. 1?

Rod Holt rholt at planeteria.net
Sun Mar 6 15:59:16 MST 2005

Dear Les.
There's a misunderstanding here. As a fact, the image of a point source 
light is just a bit larger than the light detectors in the eyeball 
(given good young eyes). A slight motion of the image on the retina 
causes one group of detectors to stop and an adjacent group to start. 
These starts and stops are the apparent twinkle. If motion were going to 
cause the whole field of view to wobble, then your vision would be 
wobbling all the time. The brain compensates for field wobble provided 
it has sufficient imformation (a resonable image, such as the whole 
sky). Since there is no coherence between the physical distribution of 
the eyeball's detectors and the pattern and/or location of the point 
source lights, none will twinkle "coherently," as you put it.
Also, a black background is necessary. As anyone who has taken 
photographs through a telescope will tell you, atmospheric disturbances 
such as heat waves when observing a low azimuths will cause the image to 
move, not twinkle.
Les Schaffer wrote:

> Rod Holt wrote:
>> The major cause of human perception of twinkle is that the image of a 
>> really, really small light source is focused to such a small spot on 
>> the retina--just a few rods & cones--that as the eyeball  moves ever 
>> so little,
> that would cause the entire field of view to wobble, not individual 
> stars seperately twinkling. further the stars would maintain constant 
> intensity. check out two distant streetlights in the desert near dusk. 
> you think the lights twinkle coherently? same for stars?
> different timescales and amplitudes too, i would guess.
> les schaffer
> _______________________________________________
> Marxism mailing list
> Marxism at lists.econ.utah.edu
> http://lists.econ.utah.edu/mailman/listinfo/marxism

More information about the Marxism mailing list