5/20/2023 0 Comments Physics gravity lab report![]() Gravity can be understood as originating from a warping of spacetime, which is shown in this artist’s impression. Critically, the torsion pendulum is very insensitive to forces from distant objects, which tug on the test mass and counterbalance together and thus do not induce rotation. Such a thin fiber is extremely compliant, so even a very weak force yields a relatively large rotation. A force on the test mass causes the torsion pendulum to rotate until it is balanced by a restoring force from the twisting of the fiber. ![]() The test-mass sphere is fixed to one end of a thin rod that is suspended at its midpoint by a four-micron-thick quartz fiber. An identical sphere on the other end of the rod acts as a counterweight. The researchers achieved this sensitivity using a detector called a torsion pendulum, which looks like a miniature version of a mobile hanging above a child’s crib. The central challenge facing Aspelmeyer’s team was to design a detector exquisitely sensitive to this gravitational force yet totally insensitive to much larger background forces pushing and pulling on the test mass from all sides. The gravitational pull of one sphere (the “source mass”) on the other (the “test mass”) a few millimeters away is more than 10 million times smaller than the force of a falling snowflake. It is hard to fathom just how extraordinarily weak gravity is for such small masses. The results, published in Nature today, bring physicists one step closer to the distant goal of reconciling gravity with quantum mechanics, the theory underlying all of nongravitational physics. The research effort born on that day has now produced its first result: a measurement of the gravitational force between two tiny gold spheres, each about the size of a sesame seed and weighing as much as four grains of rice-the smallest masses whose gravity has been measured to date. ![]() “My resolution was ‘Okay, I am going to not only measure the gravitational field of this chair, but we are going to go small, small, small!’” he recalls. The visitor’s comment was intended to bring an increasingly fanciful conversation back down to Earth, but Aspelmeyer, a professor at the University of Vienna, took it as a challenge. Ever since the work of Isaac Newton in 1687, physicists have understood gravity to be universal: every object exerts a gravitational force proportional to its mass on everything around it. Measurable or not, this force certainly ought to exist. Please see our Guide for Authors for information on article submission.Physicist Markus Aspelmeyer vividly remembers the day, nearly a decade ago, that a visitor to his lab declared the gravitational pull of his office chair too weak to measure. Please click here for more information on our author services. We also provide many author benefits, such as free PDFs, a liberal copyright policy, special discounts on Elsevier publications and much more. You must specify which Editor should review your proposal (see Editorial Board). Should you feel that you have a topic suitable for publication in one of the sections in this journal, please contact our Editorial Office,, with a proposal of no more than 1000 words. Submission of articles to Physics Reports is by invitation only unsolicited submissions cannot be accepted. ![]() Many articles published in Physics Reports have set a standard in their fields. The Editors of Physics Reports are specialized in the areas: Astrophysics and Cosmology Atomic, Molecular and Optical Physics Biological Physics Condensed Matter Physics High Energy Physics Nanoscience Non-Linear Dynamics and Complex Systems Nuclear Physics and Hadronic Physics Plasma Physics and Statistical Physics. The reader will not only be able to distinguish important developments and trends in physics but will also find a sufficient number of references to the original literature. These reviews are specialist in nature but contain enough introductory material to make the main points intelligible to a non-specialist. Each report deals with one specific subject and is generally published in a separate volume. Aims & Scope Physics Reports keeps the active physicist up-to-date on developments in a wide range of topics by publishing timely reviews which are more extensive than just literature surveys but normally less than a full monograph.
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