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 Fundamental Force Strength and Fusion
Name: John
Status: student
Age: N/A
Location: N/A
Country: N/A
Date: N/A


Question:
If gravity is the weakest of the four forces of nature, how does the gravity in stars cause fusion of nuclei of atoms, which are held together by a stronger force, the weak nuclear force? Is it a matter of strength over distance?


Replies:
When scientists compare fundamental forces, they are referring to the magnitude of the forces in a comparable situation. The strong force is much stronger than gravity in the context of the quarks and gluons that make up a proton. However, when you assemble a large amount of matter, the impact of the strong force does not accumulate the way it does for gravity. With a large amount of matter, gravitational forces add on each other, and certainly can generate forces larger than the strong force in a proton. So, yes, it is partially a length issue, but it is also an additive effect.

Actually, this explanation is a an (over-)simplification and is not rigorously correct -- to get the technically correct story, the topic to study is quantum chromodynamics (QCD), which remains an active field of research today.

Hope this helps,
Burr Zimmerman



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