# @thespacegal on Instagram

- **Type:** Image
- **Original URL:** https://www.instagram.com/p/B8ehsSVlLv_
- **Gondola URL:** https://gondola.cc/posts/19515759-thespacegal-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/thumbnails/e52f659965.jpg
- **Posted:** 2020-02-12T18:31:31.000+00:00
- **Account Owner:** Emily Calandrelli (@thespacegal) — https://gondola.cc/thespacegal

## Caption

Hi, hello⁣
IM AT LIGO (!!!!)⁣
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And THIS CHAMBER right here is where the first gravitational 〰️ waves were detected.⁣
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🤔 what is a gravitational wave? These are ripples through the fabric of spacetime 🤯and they're caused by large catastrophic events like 2 black holes merging, stars exploding, etc⁣
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〰️ how do you measure them?⁣
WITH ONE OF THE GREATEST ENGINEERING MARVELS OF ALL TIME⁣
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🔢 Gravity waves propagate like a hula hoop that is squeezed - it smooshes things in one direction and stretches them in the other. So at LIGO they have 2 long tubes shaped like an "L". They shoot lasers down each tube and because we know the speed of light we can tell if one side got longer or shorter. (More complex than this, but sort of like this)⁣ if they did, then we have a candidate gravity wave!
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🛠️ To achieve this, they needed:⁣
1️⃣Two 4km arms which are so long that you need to account for the curvature of the Earth to keep the laser beam straight⁣
2️⃣ The smoothest mirrors ever created (for the lasers to bounce off of *perfectly*)⁣
3️⃣ One of the LARGEST extreme vacuum systems ever created (in the beam tubes b/c light interacts with air molecules and we don't want that 🙅🏻)⁣
4️⃣ A way to cancel out other vibrations from Earth - (think deer, trains, earthquakes, oceans - these can shake the instrument and trick it into thinking a wave may have occured). ⁣
5️⃣ TWO LIGO facilities located 3000km apart. They need this to 1) verify that one detection at one facility wasn't an error and 2) to help locate WHERE the wave came from 📍⁣
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Y'ALL this is the coolest thing ever. It was the most expensive science project the National Science Foundation had ever funded (at the time).
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✳️ THIS has opened up an entirely new way to "SEE" THE UNIVERSE, and omg there's so much I want to say about this but I've run out of room!⁣
Check out the full segment on #XplorationOuterSpace on xplorationstation this fall. #LIGO #Universe #astrophysics #astronomy #space #scicomm

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## Tags

universe, space, scicomm, xplorationouterspace, astrophysics, ligo, astronomy

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