{"id":4345,"date":"2009-12-18T11:48:49","date_gmt":"2009-12-18T11:48:49","guid":{"rendered":"http:\/\/scienceblogs.com\/principles\/2009\/12\/18\/why-every-dog-should-love-quan-3\/"},"modified":"2009-12-18T11:48:49","modified_gmt":"2009-12-18T11:48:49","slug":"why-every-dog-should-love-quan-3","status":"publish","type":"post","link":"http:\/\/chadorzel.com\/principles\/2009\/12\/18\/why-every-dog-should-love-quan-3\/","title":{"rendered":"Why Every Dog Should Love Quantum Physics 4: Lasers"},"content":{"rendered":"

How to Teach Physics to Your Dog<\/cite><\/a> is now listed as “In Stock” at Amazon<\/a>, so it’s the perfect time to order a dozen or so copies for your last-minute holiday gift needs. <\/p>\n

“But, wait,” you say, “why do I want to teach my dog physics? Particularly quantum physics– why does anyone need to know that?”<\/p>\n

The answer is: “Lasers.” Lasers are pretty awesome, right? Let’s ask an expert:<\/p>\n

\n

If I were creating the world I wouldn’t mess about with butterflies and daffodils. I would have started with lasers, eight o’clock, Day One!<\/p>\n<\/blockquote>\n

\"i-ef28b3157f584f0bd4d72191593aa205-tb_051EvilMap.jpg\"<\/p>\n

OK, maybe he’s a bad one to ask. Still, lasers are pretty awesome, and lasers wouldn’t work without quantum mechanics.<\/p>\n

<\/p>\n

To make a laser, you need a gain medium that consists of some material (gas atoms, ions in a solid matrix, a semiconductor diode) which can be excited to a higher-energy state, from which it will return to a lower state, emitting a specific frequency of light. This is exactly the situation that drove Niels Bohr to make the first quantum model of a hydrogen atom: Bohr needed to explain the spectrum of light emitted by excited hydrogen atoms (and all other atoms, but hydrogen came first), which consists of a few very specific frequencies of light. To explain it, he needed to introduce the idea of discrete quantum states of the electrons inside the atom, with the electron moving between states by emitting light whose frequency depends on the energy difference between the two states.<\/p>\n

Bohr’s ad hoc assumptions were later justified with the development of the Schrödinger wave equation and Heisenberg’s matrix mechanics, which kicked off the great revolution in modern physics that we know as quantum mechanics. So, a laser is an essentially quantum device.<\/p>\n

And lasers are everywhere, from supermarket check-out scanners to CD\/ DVD\/ Blu-Ray players. If you’re reading this via the Internet, lasers were almost certainly involved in transmitting the message to you, via fiber-optic communications networks.<\/p>\n

So, if you want to know why quantum physics matters, lasers are one of the many reasons. That’s why any self-respecting modern dog should know about quantum physics, and why humans should want to teach them.<\/p>\n","protected":false},"excerpt":{"rendered":"

How to Teach Physics to Your Dog is now listed as “In Stock” at Amazon, so it’s the perfect time to order a dozen or so copies for your last-minute holiday gift needs. “But, wait,” you say, “why do I want to teach my dog physics? Particularly quantum physics– why does anyone need to know… Continue reading Why Every Dog Should Love Quantum Physics 4: Lasers<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"1","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[67,13,7,61,132,23,11,52,56],"tags":[],"class_list":["post-4345","post","type-post","status-publish","format-standard","hentry","category-book_writing","category-education","category-physics","category-physics_with_emmy","category-publicity","category-quantum_optics","category-science","category-science_books","category-technology","entry"],"_links":{"self":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/4345","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/comments?post=4345"}],"version-history":[{"count":0,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/4345\/revisions"}],"wp:attachment":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/media?parent=4345"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/categories?post=4345"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/tags?post=4345"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}