Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne What is Light?
Name: N/A
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: N/A


Question:
What is light? It has been described to me as radiant energy. It would seem to me that light has to be some type of physical substance flowing between the sources and wherever the light goes. What is it ?



Replies:
There are several ways to think of light. The classical description says light is an electro-magnetic wave. This means that it is a varying electric and magnetic field, which spreads out or propagates from one place to another. It is not a physical substance. The modern quantum mechanical description says that light can also be considered to be particles called photons. These carry energy and momentum but have no mass. In both descriptions, the light energy is carried by a very real and observable mechanism. But I would not call it a physical substance.



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory