Editing Gravitational Lensing

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Astronomy]]:
| Gravitational Lensing, Black Holes
|-
| Grade Range:
| [[Middle School]], [[High School]]
|-
| Format:
| [[Hands-on]]
|}

This is an thought-provoking demonstration on how we can identify black holes in outer space. It does require some background knowledge on black holes for the participant, so it works best with an older audience.

== Materials ==

* Wine Glass Bottoms
* Gravitational Lensing Images

== Safety Precautions ==

Please read the General Safety section of the [[Demonstration Safety]] page before performing this demonstration.


== Demonstration ==

# Have students pick up the wine glass bottoms and try looking through them at different objects in the room. Can they see through the center of it?
# Instead of trying to look through the center, have them try to identify objects by looking at the warped image around the center. What do they notice about the warped image?
# Have students compare what they are seeing to the images you have. Does the effect look similar?


== Why This Works ==

''Gravitational Lensing'' is an effect that we see around massive stellar objects, such as black holes. If we are trying to look at a black hole, we won't actually see it, since it doesn't emit any light, and traps any light that comes towards it. However, we ''can'' see stars and other stellar objects that are ''behind'' the black hole. Some of the light that is emitted from the star is far enough away from the black hole that it will not be pulled into it. However, the force of gravity that the black hole has will still warp the light, and cause it to curve around the black hole. This warped light we can see with telescopes, and based on how much it is warped we can determine the approximate size of the black hole, and the distance it is from the star behind it.

When we look through the wine glass bottoms, we cannot see directly through the center of them, because it is too foggy. This is what we can imagine to be our black hole, because we cannot identify it directly. However, we can see the light coming from around the center. The images we see are really warped though, and some even wrap fully around the outside of the center foggy spot. This is what the gravitational lensing effect looks like to us; the light from the star or object behind the black hole is distorted around it, and can even wrap an entire image around the black hole. You may even notice the doubling of an image through this warped area!

== Additional Information ==

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