{"product_id":"mirrorix-ligo-test-mass","title":"Mirrorix – The LIGO Test Mass \/ h ≈ 10⁻²¹ Physics Sticker","description":"\u003cp\u003eMirrorix, a hooded watcher of spacetime, stands by a shining crystal tower, a stylised mirror that feels gravitational waves.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eLIGO measures gravitational waves by comparing the lengths of two 4 km arms with laser light. At the end of each arm hangs a test mass: a 40 kg fused-silica mirror 34 cm across, hung from a four-stage pendulum to isolate it from ground vibration (Advanced LIGO, Class. Quantum Grav. 32, 074001, 2015). On 14 September 2015 a wave from two merging black holes, GW150914, stretched and squeezed the arms with a peak strain of 1.0 × 10⁻²¹ (Phys. Rev. Lett. 116, 061102, 2016).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eh ≈ ΔL\/L\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eh: gravitational-wave strain, dimensionless\u003c\/li\u003e\n\u003cli\u003eΔL: change in the difference of the arm lengths (m)\u003c\/li\u003e\n\u003cli\u003eL: arm length, 4 km\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eWith h ≈ 10⁻²¹ and L = 4 km, ΔL is about 4 × 10⁻¹⁸ m, hundreds of times smaller than a proton.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e h ≈ ΔL\/L is the simple order-of-magnitude relation; the exact factor depends on the wave's direction and polarisation. LIGO's light bounces many times in each arm, which is how it reaches this sensitivity.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003eMirrorix stands beside a glowing crystal spire with light rings around it; the quad-pendulum suspension is not drawn. Printed text: \u003cstrong\u003eMIRRORIX\u003c\/strong\u003e with the line \u003cstrong\u003eh ≈ 10⁻²¹\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50964039401575,"sku":"20840365084571556193","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50964039434343,"sku":"26276879225511137700","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50964039467111,"sku":"25061639478286574472","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50964039499879,"sku":"95203888636017625028","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/17116793195594634207_1200.jpg?v=1793658739","url":"https:\/\/pixelatedphysics.com\/es\/products\/mirrorix-ligo-test-mass","provider":"Pixelated Physics","version":"1.0","type":"link"}