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TOPICS 1. From Newton’s Gravity to Einstein’s Spacetime

GRAVITY PROBE B: Examining Einstein’s Spacetime with Gyroscopes An Educator’s Guide. TOPICS 1. From Newton’s Gravity to Einstein’s Spacetime 2. “Seeing” Spacetime with Gyroscopes 3. The Science Instrument in a Force-Free Environment ACTIVITIES

ariana-campbell
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TOPICS 1. From Newton’s Gravity to Einstein’s Spacetime

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  1. GRAVITY PROBE B: Examining Einstein’s Spacetime with Gyroscopes An Educator’s Guide • TOPICS • 1. From Newton’s Gravity to Einstein’s Spacetime • 2. “Seeing” Spacetime with Gyroscopes • 3. The Science Instrument in a Force-Free Environment • ACTIVITIES • Assumptions about Gravity • Equivalence Principle • Curved Spacetime Models • Frame-Dragging

  2. Uncovering Assumptions about Gravity 1. What does the ball represent? The magnet? The magnetic field? 2. How does the ball “know” that the magnet is there? How does the magnet “pull” the ball toward it? 3. In what ways does this model NOT accurately demonstrate Newton’s gravity? In what ways is gravity different than a magnetic force?

  3. NO HYPOTHESIS In the Principia (1687), Newton states that “there is a power of gravity pertaining to all bodies, proportional to the … quantities of matter which they contain.” As the story goes, when Newton was questioned about how his “power of gravity” transmitted from one body to another, he responded, “I make no hypothesis.”

  4. Which wagon is harder to push? Which wagon hits first? swimming pool

  5. Microscopic Angles of GP-B Geodetic effect ---------- 6600 milliarcseconds(ST curvature) Frame-dragging ------------ 42 milliarcseconds GP-B tolerance ------------- 0.5 milliarcseconds

  6. Gyroscopic Performance Orders of Magnitude Drift Rate (degrees/hour) 0 -2 -4 -6 -8 -10 -12 -14 10 10 10 10 10 10 10 10 Earth-based navigational gyros GP-B gyroscopes

  7. Roundest Gyroscope in the World Materials -- fused silica, coated with niobium Diameter --- 1.5 inches Sphericity -- < 0.3 millionths of an inch (40 atomic layers) Homogeneity -- < 2 parts per million Roundest Object in the Universe (Almost)

  8. Why do gyroscope’s stay oriented? rotational inertia Where does a gyroscope’s “inertia” come from? Mach's principle Inertial effects of mass are not innate in a body, but arise from its relation to the totality of all other masses, i.e., to the universe as a whole. Hence, the “local” behavior of matter is influenced by the “global” properties of the universe.

  9. Ultra-Low Temperatures for Superconductivity 273 Kelvin METALS 10K Niobium = 9.25K 5K Lead = 4.15K Mercury = 3.72K GP-B ProbeTemperature 1.8K Aluminum = 1.10K Tungsten = 0.0019K 0K

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