Tagged Questions
2
votes
1answer
619 views
What negative effects can pinhole glasses have on the body?
While shopping in the local supermarket yesterday, I was surprised to find this display on one of the shelves.
I also realize that I should have taken a pamphlet with me, as well as a picture of ...
12
votes
4answers
1k views
Does red light preserve your night vision?
A number of companies have started marketing LED lamps that can be switched to a red mode. The claim is that red light is less harmful to one's night vision. Given that our eyes are less sensitive to ...
16
votes
1answer
448 views
Why do stars disappear when I look at them?
I've noticed that when I'm out at night stars seem to vanish when I focus on them. I assume the reason is physiological and not astronomic. Why does this happen? I would expect that things would be ...
