General Relativity

Students engaged gravity force exploring the planet movements managing Apps [Ref.1] on own Smartphone/Tablet . We woked with mixed class of from 16 to 18 years old. We encourage to use daily own device to search informations, collect data, explore science. Using the simulation software Celestia, we calculated the orbit radius and the orbital period of 7 Jupiter satellites . “How can we sure that really the planet motions are due to a force?” “we can see the elastic force, the magnetic force, but how can we “feel” gravitational force? “. Newtonian gravity model doesn’t explain what is the cause of this force. So we decided to investigate the third Kepler law in another way. General Relativity gives us a great effort to have a new vision of mechanics. In this model gravity is NOT a force, but it can be described as a curvature of space and time (a whole 4 dimensional space-time). A new engagement starts now! We founded many amazing videos of particle motions on a warped space [Ref.4]. We realized a Spandex Universe, which is used in many educational settings to demonstrate various astronomical effects. We created a Spandex universe on a circular structure of 170cm diameter. A webcam recorded particle trajectories , the video analysis was made using the software Tracker [Ref.5]. When we put an heavy mass on Spandex, a coin falls down in quasi circular orbit , because of curvature caused by heavy mass and not as an attraction by the heavy mass. We experimented tidal forces (fig.11 ), double star, satellites formation (fig.12), gravitational waves. When we put an heavy mass on Spandex, using gyroscope App in our Smartphone, we can register on our smartphone, a curvature “vibration”, due to mechanical elasticity texture force, this perturbation is like a gravitational (mechanical) wave. It was exciting to see how this simple model can explain many complex physical phenomena. They are a qualitatively devices, but in the future we want to elaborate it with new data set. In our Spandex model the gravity is caused by space curvature . If we live in a Spandex Universe, a straight line for us may be a curved line for another observer A zero mass trajectory deflection (like light) is caused by an intrinsic curvature Planet motion may be explained as geometry curvature of space, the space distortion is caused by masses and influenced particles motions; gravity is described as the warping of space due to the presence of matter and energy. Our data match with third Kepler law, introducing a covariant space measurement. Our results are satisfactory because we can explain a great variety of phenomena such as light deflection, tidal force, satellites formation, gravitational waves. Bibliography [1] https://play.google.com/store/apps/details?id=com.tss.android https://play.google.com/store/apps/details?id=jp.danball.planet https://play.google.com/store/apps/details?id=com.rts.android.spacesim [2] http://imagej.nih.gov/ij/ [3] http://en.wikipedia.org/wiki/Jupiter_mass [4] https://www.youtube.com/watch?v=RqVKIxqIorg https://www.youtube.com/watch?v=ZkURrrACG0g https://www.youtube.com/watch?v=CvN13ZE544M&list=PL2nSpVcaaKQT_qiNgEuUxD... [5] http://www.cabrillo.edu/~dbrown/tracker [6] Middleton, C., Langston,M., Circular orbits on a warped spandex fabric, Am. J. Phys. 82, 287 , 2014 [7] http://www.einstein-online.info/spotlights/light_deflection