Only the Shadow Knows

Janet Shields

When I was a youngster, I was taught that light goes in straight lines. At some point, I also became aware that light spreads out from a light source such as a light bulb. However, it still seemed to me that I was missing something important. I couldn't figure out why shadows had such blurry edges. If the light goes straight, shouldn't the edge of a shadow be sharp? And what really bothered me was, if the light spreads out—gets bigger in a sense—and we use our pupil to grab a tiny fraction of that light, why can we see the whole object?

This article is only available as a PDF.

Download PDF

Publish Date:

Only the Shadow Knows

Janet Shields

When I was a youngster, I was taught that light goes in straight lines. At some point, I also became aware that light spreads out from a light source such as a light bulb. However, it still seemed to me that I was missing something important. I couldn't figure out why shadows had such blurry edges. If the light goes straight, shouldn't the edge of a shadow be sharp? And what really bothered me was, if the light spreads out—gets bigger in a sense—and we use our pupil to grab a tiny fraction of that light, why can we see the whole object?

Log in or Become a member to view the full text of this article.

This article may be available for purchase via the search at Optica Publishing Group.

Optica Members get the full text of Optics & Photonics News, plus a variety of other member benefits.

Publish Date: 01 January 1993


Add a Comment

Share this Article

ADVERTISEMENT
ADVERTISEMENT