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| Insert succinct description of demonstration. | Lens machined from PMMA (a.k.a. Lucite, Plexiglass, Perspex, etc; n=1.495) as per calculations in C. Darwin, "The Gravity Field of a Particle", Proc. Roy. Soc. A 249, 180 (1959), especially section 8, culminating in equation 29, which gives the deviation of the ray as a function of perihelion distance; see J. Higbie, "Gravitational Lens", Am. J. Phys 49, 652 (1981) for practical details. Looking through the lens from a viewpoint on the lens axis with the flat side facing the viewer, the lens causes incoming light rays to deviate by same amount as would be caused by a black hole with mass m=2.595 x 10^24 kg (a little less than half the mass of the Earth). This mass was chosen in order that light with an impact parameter of 1 cm would be captured into the "light ring". The radius of the light ring would be 0.5774 cm. The event horizon of such a black hole would have a radius of 0.3849 cm. Lens parameters (thickness as a function of distance from axis) were calculated by Jim Reardon, and the lens was machined on a lathe by Sara Yaeger. |
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| ||light source ||[[MechanicsCabinetBayB1|ME, Bay B1, Shelf #2]] || || | ||light source ||[[CabinetNextToElevator|Cabinet Next to Elevator, Top half, Shelf #1]] || || |
Gravitational Lens, 8C20.40
Topic and Concept:
- General Relativity
Location:
Cabinet: Optics (OP)
Bay: (A1)
Shelf: #1
Abstract:
Lens machined from PMMA (a.k.a. Lucite, Plexiglass, Perspex, etc; n=1.495) as per calculations in C. Darwin, "The Gravity Field of a Particle", Proc. Roy. Soc. A 249, 180 (1959), especially section 8, culminating in equation 29, which gives the deviation of the ray as a function of perihelion distance; see J. Higbie, "Gravitational Lens", Am. J. Phys 49, 652 (1981) for practical details.
Looking through the lens from a viewpoint on the lens axis with the flat side facing the viewer, the lens causes incoming light rays to deviate by same amount as would be caused by a black hole with mass m=2.595 x 10^24 kg (a little less than half the mass of the Earth).
This mass was chosen in order that light with an impact parameter of 1 cm would be captured into the "light ring".
The radius of the light ring would be 0.5774 cm.
The event horizon of such a black hole would have a radius of 0.3849 cm.
Lens parameters (thickness as a function of distance from axis) were calculated by Jim Reardon, and the lens was machined on a lathe by Sara Yaeger.
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light source |
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Important Setup Notes:
Setup and Procedure:
- List steps for setup then procedure.
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Cautions, Warnings, or Safety Concerns:
Discussion:
Discuss the physics behind the demonstration, explaining some of the various steps of the demonstration when appropriate.
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Videos:
References:
- List any references