{"product_id":"rapidity-plate-029-physics-poster","title":"Rapidity – Plate 029 Physics Poster","description":"\u003cp\u003ePlate 29 speaks for itself: \u003cem\u003e“Half plus half is four-fifths.”\u003c\/em\u003e\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eVelocities do not add in relativity, but rapidities do. Two boosts of 0.5c combine to 0.8c, and no number of boosts reaches c.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eβ = tanh η\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eβ: v\/c, dimensionless\u003c\/li\u003e\n\u003cli\u003eη: rapidity, dimensionless\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e0.5c ⊕ 0.5c = 0.8c: rapidities add. η has no limit; β stays below 1.\u003c\/p\u003e\u003ch3\u003eSources\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eE. F. Taylor, J. A. Wheeler, Spacetime Physics, 2nd ed. (1992).\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eOn the poster\u003c\/h3\u003e\u003cp\u003ePlate 029, “Rapidity”: the pixel-art plate with its slogan “Half plus half is four-fifths.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"9'' x 12\" (Vertical) \/ Matte","offer_id":50961874354279,"sku":"23966140584171221150","price":19.99,"currency_code":"USD","in_stock":true},{"title":"9'' x 12\" (Vertical) \/ Fine Art","offer_id":50961874387047,"sku":"17132501604598393444","price":29.99,"currency_code":"USD","in_stock":true},{"title":"9'' x 12\" (Vertical) \/ Semi Glossy","offer_id":50961874419815,"sku":"20934812217094248981","price":19.99,"currency_code":"USD","in_stock":true},{"title":"18″ x 24″ (Vertical) \/ Fine Art","offer_id":50961874452583,"sku":"77594373572698024727","price":44.99,"currency_code":"USD","in_stock":true},{"title":"18″ x 24″ (Vertical) \/ Semi Glossy","offer_id":50961874485351,"sku":"31188837350215288917","price":29.99,"currency_code":"USD","in_stock":true},{"title":"18″ x 24″ (Vertical) \/ Matte","offer_id":50961874518119,"sku":"27962241730818077383","price":29.99,"currency_code":"USD","in_stock":true},{"title":"36'' x 48\" (Vertical) \/ Matte","offer_id":50961874550887,"sku":"27094514860018395048","price":69.99,"currency_code":"USD","in_stock":true},{"title":"36'' x 48\" (Vertical) \/ Fine Art","offer_id":50961874583655,"sku":"21146057257201977251","price":119.99,"currency_code":"USD","in_stock":true},{"title":"36'' x 48\" (Vertical) \/ Semi Glossy","offer_id":50961874616423,"sku":"72057371561556349913","price":69.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/11146173704784714451_2048.jpg?v=1793633505","url":"https:\/\/pixelatedphysics.com\/zh-hans\/products\/rapidity-plate-029-physics-poster","provider":"Pixelated Physics","version":"1.0","type":"link"}