The theory of general relativity: It works. OK, it’s not exactly Earth-shattering news that Albert Einstein’s century-old idea works in real life. That’s been shown over and over. But what had been difficult for researchers to do until now was verify the theory on truly massive scales beyond the solar system, that of whole galaxies and clusters of galaxies. This week in Nature, Reinabelle Reyes and colleagues report that they did it, and that Einstein was proven correct once more.
While the find is a nice coup for Reyes’ team, its importance goes beyond just reaffirming the great scientists of yesteryear with yet another “Einstein was right” story. The existence of dark matter and dark energy is based on the assumption that Einstein’s gravity is affecting galaxies billions of light-years from Earth in the same way that it affects objects in our solar system [National Geographic]. However, if the study had shown that general relativity needed a slight adjustment at vast distances (like the nudge Einstein himself provided to Newton’s physics), that could have altered prevailing ideas about dark matter and energy. This research indicates those pesky ideas may be here to stay [Space.com].
Reyes’ approach combined the study of galaxies’ gravitational lensing (how much they bend the light from surrounding galaxies), their velocities, and how and where they formed clusters. All of these measurements combined created a system to test theories of gravity independent of particular parameters in the theories [Space.com]. What they found closely matched what you’d predict under general relativity. They tested two alternative gravitational theories, too. One, called tensor-vector-scalar (TeVeS), gave results beyond the study’s margin of error. Another, called f(R), didn’t work as well as general relativity. But it fell within the margin of error, so the scientists say it will take more research to disprove it.
Meanwhile, as the spirit of general relativity is reaffirmed in the pages of Nature, the pages upon which Einstein formulated the theory are going on display in Jerusalem. Elsa, his wife, gave the pages to Hebrew University, and they are currently part of 50th anniversary festivities at the Israel Academy of Sciences and Humanities. Each of the 46 pages, labored over between November 1915 and their publication in May 1916, has its own case, each lighted dimly in a room that has been darkened to protect the paper. There on Page 1 is the now familiar title in German: “The Foundation of the General Theory of Relativity” [The New York Times].
However, if you need more Einstein and can’t make the trip to Israel, check out his mustachioed mug on the cover of the April DISCOVER issue, on newsstands this week.
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Image: Ferdinand Schmutzer
March 11th, 2010 at 5:22 pm
I think even if the gravity was really weaker at large distances it still would not be enough to get rid of Dark Energy. That is because expansion of the Universe cannot happen w/o an energy source to drive it continuously, and that is because expansion requires constant creation of new volume of space-time and unit volume of space-time must have a constant unit amount of zero-point energy. So w/o a continuous energy source the expansion cannot really continue.
March 12th, 2010 at 4:38 am
i not sure i understand what they have achieved. If they have proved that gravity is affecting everything at the rate it should based on mass and that distance has no effect on gravity, its a very serious problem for the multiverse theory i guess. Unless our universe is the first.
March 12th, 2010 at 4:48 pm
sweet next up is the theorey for trans warp beeming during hyper speed….
March 14th, 2010 at 2:05 pm
Just a thought here. What drives the expansion of space/time? Could it be the very wierdness of quantum mechanics in a vacuum? As I understand it, particles continuously “pop” into existence and then disappear. What if when they appear, they actually create the tiny space they occupy, pushing space/time apart to make room. When they then disappear, they leave that empty space behind, adding to existing space/time. Are there enough of these “poppers” to account for observed expansion? Could this be tested somehow? How much would such particles weigh? Could an aggregate weight estimate begin to explain “dark matter?” Dark energy?
Unfortunately I am not educated enough in the field to pursue this further, or enough to know if this even makes sense. I await responses from better educated folks to either tell me I’m all wet or on to something.
March 15th, 2010 at 5:52 pm
If light can be “lensed” gravitationally, does that mean that photons have mass ? If so, the so-called “red shift” could be explained as the Doppler effect of slower light rather than expanding galaxies.
April 22nd, 2010 at 4:40 pm
Great article. We are also featuring Einstein on our blog and have posted intruging photos of his life and death. Take a look. http://www.americanbiotechnologist.com/blog/einstein-photos/