The LenseThirring Effect

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The Lense-Thirring Effect

• Alex Robson

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General Relativity

• Einstein realised the Newtonian theory of gravity
  did not account for events over large distances.
• Space is not just an empty place where things
  happen, but, combined with time, is a kind of
  fabric.

• Albert Einstein (1879-1955)

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Space-Time Fabric

• The properties of this space-time fabric dictate
  how things move within it.
• If a heavy spherical mass were placed on a rubber
  sheet, it would deform this sheet.
• In the same way mass-energy in space-time warps
  the area accordingly.

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The Lense-Thirring Effect

• In 1918, Joseph Lense and Hans Thirring predicted
  frame dragging.
• Any object with mass warps space-time around
  itself.
• If this object is spinning, it will induce a
  second distortion as it twists space-time around
  itself.
• If the space around this first mass is being
  dragged, then objects in or near this space
  should also affected.

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Detecting the Lense-Thirring Effect

• Two satellites, LAGEOS and LAGEOS 2 have been
  used to detect the Lense-Thirring effect over 11
  years.
• Each satellite is a highly reflective sphere.
• Laser signals are bounced off these satellites,
  and then analysed.
• The result from this is 99 of the predicted
  value (from Einsteins general theory of
  relativity), with a 10 error margin.
• Another satellite, Gravity Probe B, is intended
  to measure the Lense-Thirring Effect.

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Summary

• Any object with mass warps space-time.
• If this mass spins, it will induce a second
  distortion around itself, as it drags the
  space-time fabric.
• Objects within this region of space should be
  affected by it.
• The Lense-Thirring effect has been confirmed with
  the LAGEOS and LAGEOS 2 satellites.
• Gravity Probe B is also to measure the
  Lense-Thirring Effect.