4:30 PM
Astronomy Pirate
We are surrounded by swirling and distorted time and space, and no this not the effect of the Cinco de Mayo tequila... Well maybe some of it is...
Yesterday NASA announced that Gravity Probe B (GP-B) confirmed two of Einstein's space-time theories. The first is the geodetic effect, or the warping of space and time around a gravitational body. The second is frame-dragging, which is the amount a spinning object pulls space and time with it as it rotates.
It is OK to be asking 'what are these theories and what probe' and 'when did this mission happen'. Honestly, it was tucked into a corner of my mind that I had entirely forgotten about until I got about half way through reading the NASA release.
I don't want to lose to many people on to many of the boring aspects of this mission, as it requires a good knowledge of physics. If you are interested in some of the deeper science behind the mission, I recommend checking out http://einstein.stanford.edu/.
The result is that we now know that there is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.
Often times general relativity is thought to be one of those things where there will never be definitive proof, but this experiment changed that. One of the reviewers of the Gravity Probe B's results, Clifford Will of Washington University in St. Louis, predicts "this will be written up in textbooks as one of the classic experiments in the history of physics."
The idea behind it is that, according to Einstein's theories, time and space are woven together into a four-dimensional sheet called "space-time." The mass of objects, like the Earth, creates dimples in this fabric. Now the Earth also spins, which twists the dimple. Imagine something spinning in a jar of honey, the honey around the object gets pulled with the spin.
This is was what GP-B was created to detect. After over 40 years in development, it was launched in 2004, making this project one of the longest running in NASA's history. The idea of the experiment was simple, but a monumental task to pull off.
The basic idea is that there are 4 gyroscopes put into space. The gyroscopes have a spin axis pointed at a fixed reference point, a distant star. If free from external influence, the gyroscopes should point at the star forever. However, if space is twisted, over time they will drift off of the star. The change in direction relative to the star can be used to measure the twists of space-time.
The epic part comes from what was done to perform this experiment. The gyroscopes are the most perfect spheres ever made by humans. At 1.5 inches across, their surfaces never vary more than 40 atomic layers.
Thirteen new technologies were invented for GP-B, including a way to measure gyroscopes without disturbing them. These new technologies have been used in various way already. This includes systems that allow airplanes to land unaided, GPS technologies, drag-free satellite concept that allows for Earth observing satellites, determining the cosmic background radiation, and magnetic field shielding.
The other cool thing is that this data proves the existence of distorted space-time. It can be duplicated when studying other celestial bodies. It has been suggested that in regions with a large and active space-time vortex, you could see a whole manner of distortions. In a system as complicated as black hole binary - one black hole orbiting another - space-time would be entirely flipped over.
Hundreds, maybe more then a thousand, people have been involved with this experiment. A lot of them are young, including high school students and undergraduates. It was a heroic feat. The probe was decommissioned in December 2010 and ceased data collection, but will have a long-term impact on physics.
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| Distorted space and time around Earth. (Credit: Stanford) |
Yesterday NASA announced that Gravity Probe B (GP-B) confirmed two of Einstein's space-time theories. The first is the geodetic effect, or the warping of space and time around a gravitational body. The second is frame-dragging, which is the amount a spinning object pulls space and time with it as it rotates.
It is OK to be asking 'what are these theories and what probe' and 'when did this mission happen'. Honestly, it was tucked into a corner of my mind that I had entirely forgotten about until I got about half way through reading the NASA release.
I don't want to lose to many people on to many of the boring aspects of this mission, as it requires a good knowledge of physics. If you are interested in some of the deeper science behind the mission, I recommend checking out http://einstein.stanford.edu/.
The result is that we now know that there is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.
 |
| A much more detailed and science-y image. (Stanford) |
Often times general relativity is thought to be one of those things where there will never be definitive proof, but this experiment changed that. One of the reviewers of the Gravity Probe B's results, Clifford Will of Washington University in St. Louis, predicts "this will be written up in textbooks as one of the classic experiments in the history of physics."
The idea behind it is that, according to Einstein's theories, time and space are woven together into a four-dimensional sheet called "space-time." The mass of objects, like the Earth, creates dimples in this fabric. Now the Earth also spins, which twists the dimple. Imagine something spinning in a jar of honey, the honey around the object gets pulled with the spin.
This is was what GP-B was created to detect. After over 40 years in development, it was launched in 2004, making this project one of the longest running in NASA's history. The idea of the experiment was simple, but a monumental task to pull off.
The basic idea is that there are 4 gyroscopes put into space. The gyroscopes have a spin axis pointed at a fixed reference point, a distant star. If free from external influence, the gyroscopes should point at the star forever. However, if space is twisted, over time they will drift off of the star. The change in direction relative to the star can be used to measure the twists of space-time.
 |
| One of the gyroscopes. (Stanford) |
The epic part comes from what was done to perform this experiment. The gyroscopes are the most perfect spheres ever made by humans. At 1.5 inches across, their surfaces never vary more than 40 atomic layers.
Thirteen new technologies were invented for GP-B, including a way to measure gyroscopes without disturbing them. These new technologies have been used in various way already. This includes systems that allow airplanes to land unaided, GPS technologies, drag-free satellite concept that allows for Earth observing satellites, determining the cosmic background radiation, and magnetic field shielding.
The other cool thing is that this data proves the existence of distorted space-time. It can be duplicated when studying other celestial bodies. It has been suggested that in regions with a large and active space-time vortex, you could see a whole manner of distortions. In a system as complicated as black hole binary - one black hole orbiting another - space-time would be entirely flipped over.
Hundreds, maybe more then a thousand, people have been involved with this experiment. A lot of them are young, including high school students and undergraduates. It was a heroic feat. The probe was decommissioned in December 2010 and ceased data collection, but will have a long-term impact on physics.
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