Einstein’s theory of relativity, sparked interest almost a century ago. He challenged the long-held beliefs of the world around earth: that space and time are different for each planet, creating displacement. An easy way to visualize this depiction is taking a blanket and holding it taut, and throw a ball onto the blanket. The ball creates a dimple in the fabric. Another visual is the trampoline, when children are laying on the top, the fabric is displaced to accommodate the weight of the people. The Earth does the same thing, but on a different level. The Earth is not a stationary object—it spins and rotates 360 in 24 hours and makes a complete rotation around the sun in 365.25 days. These motions create the same effect all around the planet, creating the four-dimensional space-time continuum that Einstein postulated.
This theory has been so engrained in the minds of the science community that it has overflowed into the sci-fi genre in films, tv shows, and novels. The concept of space-time distortion has fascinated millions since Einstein proposed the theory.
And for decades, NASA has been attempting to confirm Einstein’s theory with concrete data. That experiment came to fruition in 2011. On May 4 of that year, NASA released the findings of the Gravity Probe B (GB-P) mission. This mission, started in 1963, in the middle of the space race, and has resulted in over 47 years of data collection and inventions to be able to accurately gather the data from Earth’s orbit, while eliminating other factors in the process.
For GB-P to work, the satellite must be able to remain fixed on a particular location. As the satellite orbits the earth, if space-time does not exist, the satellite should be fixed on that same point, with each revolution around the Earth. If the satellite does not remain fixed, it could be indicative of the space-time aspect that Einstein believed.
Measuring the Wobble
To measure this, NASA had to create a perfect sphere (or nearly so) to accurately collect the data. If the satellite was not a perfect sphere, the wobbling could occur due to other effects instead. In the 1960s-1980s, the technology simply was not there. In the 90s and early 2000s, they were able to create a series of perfect spheres (or almost perfect) within 40 atomic layers called gyroscopes. NASA made four of these spheres from silicon and fused quarts, with an appearance and size reminiscent of a ping-pong ball; the gyroscope have a diameter of 1.5”.
How to Measure the Wobble
The experiment would be measured based upon the variation from the fixed location. Scientists calculated that due to the spin of the Earth, the gyroscope would drift 0.041 arcseconds each year (with one arcsecond being equal to 1/3600 degrees). To measure for any additional arcseconds, the gyroscope had to have a measuring capability up to 5/10,000 arcsecond. The ability to measure this has been a recent endeavor, unimagined in the early days of the project.
The satellite portion also had to be drag-free so that it wouldn’t disrupt or interfere with the calculations of the gyroscope. The gyroscope was placed in cylindrical clear containers. These containers contained an apparatus to suspend the gyroscope. In doing so, scientists had a means of attaching the gyroscope without interfering with any of its functions.
The Gravity Probe Begins
In 2004, NASA launched the Gravity Probe B. Once in orbit, the GB-P recorded data for over a year, with over 5 years of analysis as well. The analysis was trifold: examining daily, monthly, and overall data. This trifold set of analysis allows for the most comprehensive analysis to prove the existence of time-space. This allowed scientists at NASA to confirm if any variations were due to the space-time component or a result of outside forces during that time period. Ultimately, the analysis was very time-costly: one year of data resulted in five years of analysis, concluding in 2010. The findings were released in the spring of the following year.
Over the course of the year, the Gravity Probe B recorded both geodetic precession and frame dragging at 6.600 plus or minus 0.017 arcseconds and 0.039 plus or minus 0.007 arcseconds respectively. Geodetic precession is the wobble of the gyroscope created by the static mass of the planet, while frame dragging is the wobble created by the spin of the planet. The geodetic creates the dimple, while frame dragging creates the twisting motion that is often associated with the theory of relativity. Finding data for both proves the validity of Einstein’s theory.
Effects of the Findings
The Gravity Probe B project resulted in a confirmation of Einstein’s theory. As a result, this affects scientists’ understandings of planets, black holes and the correlation with space and time. The finding presents new possibilities: that a binary black hole system (two-black holes orbiting one another) is actually possible according to the findings here.
The overall project resulted in 13 new inventions, as well as highlighting the use of gyroscopes to measure the particular space-time component for Earth. This can be applied to all of the planets within the Solar System to increase scientists’ understanding of those planets.
Lastly, the project involved members from all strata of society: from high school, college, and graduate students to professors, scientists, and astronauts.
Overall, the Gravity Probe B project was a complete success. With new inventions and measurements that were not possible in previous decades, the GB-P accurately measured the wobbling of the gyroscope due to the earth’s spin and mass, using a gyroscope made from the most nearly perfect sphere made by man yet. The findings also solidified the gyroscope as a potential favorite for data collection.
The data collected solidifies Einstein’s theory as a reality, with greater applications and possibilities to explore: the possibility of binary black holes, as well as calculating the exact effect of space-time on all of the major planets in the Solar System and beyond.
And even sci-fi fans can rejoice; one of the major components has been verified by scientific data, with much more to be explored in the coming years.