Gravitational Waves Review

Group Slides

Foundation Question: What is spacetime?

A 4-dimensional space where 3 coordinates define spatial location and the the fourth coordinate specifies the time. A point in spacetime represents an event. Examples of events include the explosion of a fire cracker, or a dentist appointment. For both of these events, we have a spatial location and the time at which it occurs.

Foundation Question: What is spacetime?

Spacetime is a mathematical model that relates time to the three dimensional space creating four dimensional continuum.

Foundation Question: What is spacetime?

Spacetime is a mathematical construct that relates the three-dimensions of space with the dimension of time to form a structure that relates space and time into a single unified four-dimensional structure

Group 1 Question: What are gravitational waves?

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A gravitational wave is a source of energy moving through space sheets.

Group 1 Question: What are gravitational waves?

Ripples - alterations - of spacetime.

Group 2 Question: How do we seek to detect gravitational waves?

By looking for the distortion of spacetime (i.e., its stretching and squeezing) as a gravitational wave passes by. Laser interferometers are useful for this purpose, since they allow one to measure minute changes in lengths along the two arms.

Group 2 Question: How do we seek to detect gravitational waves?

1. WHY? We would like another test of GR. GW should allow us to observe much more of the universe than other telescopes. GW astronomy allows us to observe phenomena not observable with other messengers (black hole mergers). Not dependent on EM waves.
2. HOW: extremely sensitive interferometers have been successful. Also might be able to use pulsar timing.

Group 3 Question: What are the sources of gravitational waves?

• Any accelerating mass
• Large amplitude gravitational waves can be created by coalescing stars, neutron stars, and black holes
• …. and of course, warp drives :-)