Curved Space

7F20.201 | 0-0
Catalog: 
7F20.201
Location: 
0-0
Room: 
PS F175
Quantity: 
1
Setup Time: 
2 Days
  • demonstration image
    The demo is kept cloaked so that students can not see the demo before class.
  • demonstration image
    The curtain on the back can be dropped after class starts. There is a rubber sheet stretched over a frame with rods that can be used to stretch the sheet. A single light and three cameras are used.
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    An AV selector switch is used to switch the three cameras to the video projector and simultaneously to the small LCD monitor. The output of the selector switch goes to the input of the video distribution amp. One amp output feeds the monitor, another the projector. The lab jack is used to elevate the camera stand for the side view. Using an outlet strip with sid outlets for ac adapters means it will all fit on one strip.
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    The top camera and light. The light is important to hide shadows that might give away the curvature of the rubber sheet.
  • demonstration image
    View from the top camera shows the entire rubber sheet.
  • demonstration image
    A close up of point A and the measuring tape.
  • demonstration image
    The view from the side camera.
  • demonstration image
    A blurred ball can be seen following curved space.
Safety: 
Disclaimer
Description: 

A rubber sheet represents Euclidian Space when not stretched. A dowel stretches the rubber sheet at the desired location. Balls can be rolled on the surface to show how space and time are warped. It can be shown that the shortest distance between two points is no longer a straight line.

Instructions: 

The apparatus is cloadked so that the students cannot see it. Cameras are used to project the 2D image for the students. The image appears the same in 2D whether the rubber sheet is flat or depressed. Measurements are taken on camera showing a circle of constant circumference with a changing diameter and that sometimes the shortest distance between two points is a curved line. The students become very engaged trying to figure this out. Then a side camera shows the 3D rubber sheet and reveals the secret. As a follow-on, right angles are drawn on a balloon, and then connected to form a 270 degree triangle. A black ping pong ball is rolled across the curved space.

Parts: 

Video of Hester�s Lecture (H 156) Frame for stretching rubber sheet Level (H 359) Rubber Sheet (PSH frig) Set of A,B,C points Balloon & marker for 270 degree triangle (PSH frig) 3 1.5m tapes Short meter tape attached to plunger rod with electric tape Blac

Notes: 
May not work in all lecture rooms because of the technology requirements.
Equipment Information: 
Do not leave the rubber sheet stretched more than 1 night, preferably less. Do not leave the sheet depressed any longer than necessary. Be sure to check that the top of the apparatus will clear the door, and leave a little extra for the height increase wh
Link: 
http://pirt2.asu.edu/DCS/7F20-201CurvedSpace.doc
Cross Reference: 
7F20.201(21).jpg