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Gravity Probe B

Testing Einstein's Universe

What is the Purpose of Gravity Probe B?

The scientific purpose of this project is to test Einstein's theory of General Relativity.   This theory has only been partially verified and is one of the least tested of all physical theories (for more information on the testing already done and alternate theories of gravity, reference The Story of Gravity Probe B).   Until a theory is thoroughly tested, we cannot accept it as fact, and we cannot reliably base further theory or engineering on its postulates.

Is Gravity Probe B Worth Doing?

Why are we doing what we are doing? Why is the government spending tax money to fund the GP-B project? Though it may be a tremendous scientific and technological challenge, is it important to the world at large? Do we need to test a theory that has been accepted and used for over eighty years? Underlying these questions is the issue of whether or not we, as a society, should fund basic research.

Should we do basic scientific research such as Gravity Probe B?

What do we gain materially? The results of basic scientific research over the years have helped humanity in thousands of different ways. Think of radar in air traffic control, storm predictions and electrocardiograms. The financial payback is conservatively estimated as a 6:1 ratio; that is, for every dollar spent on research, citizens see a six dollar return. According to the White House, more than half of the United States' economic productivity growth in the last 50 years is attributable to technological innovation and the science that supported it. The cost of all U.S. science, space & technology programs is roughly 1% of the annual federal budget. Continuing research builds our base of knowledge, which through serendipity allows the invention of technology. Engineers and inventors of technology, such as Thomas Edison, are able to build on what is already known; allowing them, for example, to exploit electricity and channel it into useful things like light bulbs. Continuing revolutionary technology is what drives the U.S. economy and keeps our standard of living high. The advancements in technology flow everywhere and improve the world's standard of living. It allows a person in the wilderness of Bangladesh to have a Teflon® pan and use less fuel for cooking, making life a little easier.

Sometimes it is hard to envision where a better understanding of scientific laws and the physical universe will take us. But if we do not gain the understanding, the light bulbs of the future will never be invented. Think of all the great inventors who had the initiative to build on scraps of scientific evidence which to others seemed useless and unconnected to anything practical (check out Scientific American's "Connections" for some neat examples). If those inventors had not had research evidence available, they would not have had a place to begin their great work.

We invite you to read about some of the defining discoveries made in other areas of fundamental physics. Here are some historical examples of basic scientific research that seemed wasteful to most of society at the time, and some of the surprising results.

Why study Gravity?

Gravity is the least understood of all the fundamental forces, but mass and space, which are governed by gravity, are the building blocks and fabric of our universe. General Relativity is the most fundamental theorem of science about the nature of gravity. Gravity Probe B is a basic research project testing this theory. If the answers from GP-B are different from what is to be expected from Einstein's theory then a number of fundamental assumptions in physics are affected.

If we better understand the nature of mass and space, we may be able to do things previously undreamed of. So far, studies of relativity have yielded atomic clocks, guidance systems for spacecraft and the Global Positioning System. We are limited only by our own imaginations when it comes to applications of science. Who knows? Maybe we can someday learn to manipulate gravity as thoroughly as we now manipulate electricity. We cannot foresee all that may come from a better understanding of space-time and mass-energy, but a theorem about these fundamental subjects must be thoroughly examined if we are to use it to our advantage.

What has GP-B already done for society?

By manufacturing and machining the world's roundest objects (our gyroscopes), we have achieved new levels of accuracy of measurement, machining and material purity. We have educated hundreds of undergraduate students in the fields of aerospace, computer programming and physics through their work with us. Many of these students go on to work in industry, taking their ideas and experience with them. Stanford has awarded degrees to over seventy graduate students, each one writing a ground-breaking thesis researching Gravity Probe B for his or her Ph.D. A group of our students have gone on to create a successful company, IntegriNautics, whose primary focus is precision navigation and automated systems, including the automated landing of commercial aircraft. Others have invented methods for automated farm-field plowing (check out the news article from the Stanford Report) in the course of their research, just to name a few of the successes. If you'd like to see more of our technology spin-offs, have a look.  To see what NASA has done for you lately, check out their Spinoffs Web Site.

In Closing...

It is a striking realization that arch-fundamentals of the physical world and human experience of it such as time, mass, gravity and electromagnetism are often taken for granted while they remain in fact among the deepest of the enigmas of physics.

Fundamental knowledge, whether it concerns the origins of the Universe, metamorphoses of inanimate matter or the human psyche, determines our ability to evaluate our place in the world, grasp the past and prognosticate the future. The search for knowledge and truth distinguishes human beings from all other living creatures known to us. Ultimately, occasionally in a straightforward, sometimes in a circuitous way, knowledge leads to discoveries, inventions, and applications that change the human condition. The desire for a deeper understanding of the great mysteries of life has defined not only human intellect but also some of the most remarkable human actions and achievements since the dawn of civilization. We are proud to be a part of this ancient quest.