PureInsight | October 7, 2002
According to the news from New Scientist.net on September 22nd, French scientists claimed that hidden extra dimensions are causing measurements of the strength of gravity at different locations on Earth to be affected by the planet's magnetic field. If the result is confirmed, it will be the first evidence for the existence of the hidden extra dimension.
Almost all measurements of G have used variations of the torsion balance technique pioneered by English scientist Cavendish 300 years ago. In 1982, a group reported the most precise measurement of G to date, which had an uncertainty of 0.0128%. Although this seems quite precise, the fractional uncertainty in G is thousands of times larger than those of other important fundamental constants. The more puzzling fact is the new values of G from measurements by respected research teams in Germany, New Zealand, and Russia disagree wildly. For example, a team from the German Institute of Standards led by W. Michaelis obtained a value for G that is 0.6% larger than the accepted value; a group from the University of Wuppertal in Germany led by Hinrich Meyer found a value that is 0.06% lower, and Mark Fitzgerald and collaborators at Measurement Standards Laboratory of New Zealand measured a value that is 0.1% lower. The Russian group found a curious space and time variation of G of up to 0.7%.
The gravity constant G, which describes the strength of the gravitational pull that bodies exert on each other, has interested physicists for over 300 years and, except for the speed of light, it has the longest history of measurements. Yet, it is the most poorly determined of the constants of nature. Currently, the two most accurate measurements have experimental errors of 1 part in 10,000, yet their values differ by 10 times that amount. So physicists are left with no idea of its absolute value.
Jean-Paul Mbelek and Marc Lachieze-Ray of the French Atomic Energy Commission near Paris offered their solution by taking into account the location of the labs where the experiments were carried out. The pair suggest that electromagnetism and gravity influence one another enough for gravity's pull to be noticeably affected by the Earth's magnetic field.
Their work is based on string theory, which tries to unify all the forces, including electromagnetism and gravity, by invoking the existence of several extra spatial dimensions. In a paper submitted to Classical and Quantum Gravity and presented at a meeting of the European Astronomical Society in Porto, Portugal, the researchers calculated the values they would expect G to have at different locations around the world. They say it should be greater where the Earth's magnetic field is stronger, with the highest measurements at the north and south magnetic poles. The values of G measured so far seem to fit with that idea. Studies of the Sun also support the theory. To make mathematical models of the star's interior tally with experimental data, physicists have to use a lower value of G than is traditionally agreed.
Although gravity is the interaction that scientists began studying the earliest, it is the interaction that scientists know the least about and it has troubled scientists for a long time. Many of its properties are very different from those of other interactions and its current theory also contradicts many leading theories in modern physics such as quantum field theory. Recent discoveries from astronomy have shown that gravity theory can not describe the motion of galaxies and the universe on a large scale. In the cultivation community, it has been known for a long time that people who cultivate well enough can easily levitate, which is difficult to explain by current gravity theory. These days, some scientists who study the Brane theory suspect that gravity probably is not a fundamental interaction. In another word, gravity is only a phenomenon, and scientists have not yet gotten to the truth of it.
References:
1. http://www.npl.washington.edu/eotwash/gconst.html
2. http://www.newscientist.com/news/news.jsp?id=ns99992814
3. http://www.esi-topics.com/brane/interviews/DrJian-XinLu.html
Translated from: http://www.zhengjian.org/zj/articles/2002/9/30/18723.html
