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 Aether
Name: Darell
Status: educator
Age: 40s
Location: N/A
Country: N/A
Date: 2000-2001

Regarding the "aether", I understand that the concept was dropped from physics due to the acceptance of the theory of relativity and experiment by Michaelson and Morley showing that the speed of light is a constant despite linear motion. My question is how to interpret the following thought experiment: imagine that we are in an "Einstein elevator" i.e. we are enclosed so we have no external referents. Relativity implies that we cannot distinguish gravitational force acting on our elevator from acceleration. OK, but consider this: suppose I am in the elevator and I have 2 small weights connected by a spring scale. Assume for simplicity that there is no gravity or linear acceleration so I am functionally weightless. Now at the start of the thought experiment I hold the scale by its center of gravity, it will measure 0. Now I give the weights and scale a spin about their center of gravity. The scale now indicates a force. But the scale will continue to indicate a force even if the elevator is spun in synchrony with the scale. This indicates that rotational motion is not relative, it is absolute and it points to an absolute frame of

No. Different viewers will still disagree on the linear speed of the scale system as a whole, so it doesn't define an absolute frame of reference as the aether was thought to do. It's true that everyone will agree the scale system is rotating, and it's true this is because rotational motion involves acceleration, which is not relative.

Tim Mooney

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 (, or at Argonne's Educational Programs

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

Argonne National Laboratory