Click on image for full size
Courtesy of Tracey Keifer. Emilio Segre Visual Archives. American Institute of Physics.
It Looks Like Einstein Was Right! Speed of Light and Gravity are Equal!
News story originally written on January 9, 2003
To make his most well-know theory, physicist Albert Einstein had to guess that the speed of gravity was equal to the speed of light. Now, scientists have found that he was likely right!
In 1915, Einstein developed his General Theory of Relativity to explain how gravity and motion can affect time and space. Today, Einstein’s theory is very important for many scientists trying to understand the Universe.
His theory assumes that the force of gravity acts at the same speed as the speed of light. The speed of light can be measured, but scientists found that it is very difficult to accurately measure the speed of gravity. While Einstein's assumption appeared to be true, it had never been tested in detail before now.
Scientists had the opportunity to test it when, on September 8, 2002, Jupiter passed in front of a distant quasar. The planet’s gravity made the quasar appear to move in the shape of an ellipse through the sky. The scientists used the shape of the quasar’s motion to calculate that the speed of gravity is nearly the same as the speed of light!
Last modified January 9, 2003 by Lisa Gardiner.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, as well as books
on science education!
You might also be interested in:
It was another exciting and frustrating year for the space science program. It seemed that every step forward led to one backwards. Either way, NASA led the way to a great century of discovery. Unfortunately,...more
The Space Shuttle Discovery lifted off from Kennedy Space Center on October 29th at 2:19 p.m. EST. The weather was great as Discovery took 8 1/2 minutes to reach orbit. This was the United States' 123rd...more
A moon was discovered orbiting the asteroid, Eugenia. This is only the second time in history that a satellite has been seen circling an asteroid. A special mirror allowed scientists to find the moon...more
Will Russia ever put the service module for the International Space Station in space? NASA officials want an answer from the Russian government. The necessary service module is currently waiting to be...more
A coronal mass ejection (CME) happened on the Sun early last month. The material that was thrown out from this explosion passed the ACE spacecraft. The SWICS instrument on ACE has produced a new and very...more
J.S. Maini of the Canadian Forest Service called forests the "heart and lungs of the world." This is because forests filter air and water pollution, absorb carbon dioxide, release oxygen, and maintain...more
In late April through mid-May 2002, all five naked-eye planets are visible at the same time in the night sky! This is includes Mercury which is generally very hard to see. You won't want to miss this!...more