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, the General Theory of Relativity, 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, proposing that matter causes space to curve. Today, Einstein’s theory is very important for many scientists trying to understand the Universe and the Big Bang.
His theory assumes that the force of gravity acts at the same speed as the speed of light. Until recently this assumption had not been tested thoroughly. While the speed of light has been measured as 299,800 km/sec, scientists found that it is very difficult to accurately measure the speed of gravity. Einstein's assumption appeared to be true, based on indirect evidence, but it had never been comprehensively tested before now.
Scientists had the opportunity to test this assumption of Einstein's theory when, on September 8, 2002, Jupiter passed in front of a distant quasar called J0842. This week they released their findings at the meeting of the American Astronomical Society in Seattle, WA. They reported that the planet’s gravity bent the quasar’s radio waves, making the quasar appear to move in an elliptical shape through the sky according to the observations of many radio telescopes in the United States and Germany. From the shape of the quasar’s motion, the scientists calculated that the speed of gravity is nearly the same as the speed of light!
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, ranging from seismology
, rocks and minerals
, and Earth system science
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 at 2:19 p.m. EST, October 29th. The sky was clear and the weather was great as Discovery took 8 1/2 minutes to reach orbit for the Unitied...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 are demanding an answer from the Russian government. The necessary service module is currently waiting...more
During a period of about two days in early May, 1998, the ACE spacecraft was immersed in plasma associated with a coronal mass ejection (CME). The SWICS instrument on ACE, which determines unambiguously...more
J.S. Maini of the Canadian Forest Service has referred to forests as the "heart and lungs of the world." Forests reduce soil erosion, maintain water quality, contribute to atmospheric humidity and cloud...more
In late April through mid-May 2002, all five naked-eye planets are visible simultaneously in the night sky! This is includes Mercury which is generally very hard to see because of its proximity to the...more