NASA probe confirms Einstein’s prediction
If you wish to know more about this, do go here directly on the NASA site : http://www.nasa.gov/home/hqnews/2011/may/HQ_11-134_Gravity_Probe_B.html
Or here on the National Geographic site which explains it with lesser technical jargon but nicer graphics: http://news.nationalgeographic.com/news/2011/05/110505-einstein-theories-confirmed-gravity-probe-nasa-space-science/
For the layman version, CBC reports:
According to Einstein’s theories of relativity, the mass of Earth dimples space-time like a heavy person sitting in the middle of a trampoline.(NASA)
A NASA probe circling the Earth has found evidence that confirms two key predictions based on Albert Einstein’s theory of general relativity.
The results from the Gravity Probe B mission show that the Earth’s mass does warp space and time, which are interlinked, NASA announced Wednesday.
They also confirm that the Earth does drag space-time with it as it rotates, as predicted.
“Imagine the Earth as if it were immersed in honey. As the planet rotates, the honey around it would swirl, and it’s the same with space and time,” Francis Everitt, the Stanford University physicist who led the mission, said in a statement.
The results are published in the journal Physical Review Letters.
Space-time and relativity
“German-American physicist Albert Einstein’s theories of special relativity and general relativity say that space and time are woven together into four-dimensional “space-time.” The mass of Earth dimples this “fabric” like a heavy person sitting in the middle of a trampoline. Gravity results from the tendency of other masses to follow the curve of space-time and roll into the dimple. The theories predict that as the Earth spins, it should twist the dimple — an effect that should be measurable using precise gyroscopes.
Gravity Probe B was designed to test the predictions by taking measurements from four ultra-precise gyroscopes. Those instruments contain rotors that NASA bills as the “most perfect spheres ever made by humans,” allowing them to spin indefinitely without drifting from the alignment of their rotation.
The gyroscopes were aboard a spacecraft circling the Earth in a polar orbit — that is, it travelled perpendicular to the Earth’s rotation, passing over both poles during each orbit.
The experiment was set up so the gyroscopes’ axes of rotation should always point in the same direction — toward the “guide” star IM Pegasi — provided the Earth’s gravity did not affect space and time.
However, the researchers detected tiny, measurable changes in the direction of the gyroscopes’ spins, confirming that the Earth’s gravity does:
- Warp space and time around it, which is called the geodetic effect.
- Pull space and time with it as it rotates, an effect called frame dragging.”
Somewhere in the late 1980s a little girl was obsessively reading through her dad’s old Life Nature Library encyclopedia collection and a particular book she loved the most: “The Universe”. There on page 178 and 179 was the picture of a famous white-haired scientist and a chapter next to it with fascinating self-explanatory diagrams and a write-up: “Is the Cosmos Curved? And if so, how curved?” The essence of Einstein’s theory was that the presence of matter distorts space and makes it curve. The concept of space curvature stemmed from many-dimensional, non-straight-line geometry created abstractly though equations. Just as a surface can curve in ordinary three-dimensional space, so in non-Euclidian geometry a three-dimensional space can itself curve in four-dimensional space. It is difficult to visualize such a curved space because man is not four-dimensional, but from a purely logical perspective it is a clear possibility. The chapter went on to elaborate much more of course about General Relativity.
Well, it’s wonderful to find out that NASA proves that he was right, after all. What had fascinated this girl years ago in a big book were in fact words of proven wisdom.
So, a perfect occasion to place Tim Minchin’s hilarious animated poem, Storm. (Not for everyone, alas – watch at your own risk but don’t complain about getting ‘offended’. Only for those with a good sense of humour.) I love it though. Absolutely. This video is so true on so many different levels in our PC-world. And though yoga of course has unmistakable absolute proven physical benefits, as well as turmeric and curcumum used in Ayurveda, as has been proven through scientific research and tests for prostate cancer, (and mind you, the video doesn’t talk of those), the apt take on homeopathy and other pseudo-science and psychic mumbo-jumbo that the video takes the masks away from is spot-on. A f****ng brilliant piece of work, as Minchin would say. Feel free to quell any Storm-types (and idiotic Secret-types or nagging EatPrayLove-types) around to down their vociferous ignorance-laced-with-remarkable-certainty lines with this lovely clarity of reality, logic and facts . Enjoy:
(to turn off the captions, simply click on the ‘cc’ button on the youtube task bar.)
An excerpt from the National Geographic article:
Doing What Einstein Thought
To conduct these tests, Gravity Probe B used a device called a star tracker to keep one end pointed at a single star, IM Pegasi, while in a polar orbit 400 miles (644 kilometers) above Earth.
If we lived in a universe that behaved as envisioned by Isaac Newton—in which the geodetic effect and frame dragging don’t occur—then the gyroscopes would stay aligned with the star forever.
In Einstein’s universe, however, the direction of the spin axis of Gravity Probe B’s gyroscopes should gradually change due to the mass and rotation of Earth.
“Imagine the Earth is immersed in honey, and you can imagine the honey would be dragged around and [an object in the honey] would also be dragged around,” Everitt said. “That’s what happens in the gyroscope.”
Sifting through the data, the team found evidence of an angular change in the gyroscopes’ orientation of about 6,600 milliarcseconds over the course of a year.
A milliarcsecond, Everitt explained, “is the width of a human hair seen at the distance of 10 miles [16 kilometers]. It really is a rather small angle, and this is the accuracy which Gravity Probe B had to achieve.”
The change is so small, in fact, that Einstein didn’t think measuring it was even possible.
In his 1953 book The Meaning of Relativity, Einstein wrote that frame-dragging effects “are actually present according to our theory, although their magnitude is so small that confirmation of them by laboratory experiments is not to be thought of.”
But now, “thanks to NASA,” Everitt said, “we’ve done more than think about them. We’ve actually measured them.”
Gravity Findings to Unravel Distant Mysteries?
Although the results are only now being released, the Gravity Probe B satellite has completed its work, and it was decommissioned in December 2010.
Funded since 1963, Gravity Probe B is one of the longest running projects in NASA history. Scientists had the idea for the experiment before the required technology—such as the star tracker and gyroscopes—even existed…….
For the rest, click here.