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Question: How can a pigeon find its way home?
Let me begin to answer that question with a question of my own! What do pigeons, Albert Einstein and modern physics have in common? Einstein developed the general theory of relativity, which led to a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics; his work was pivotal in establishing quantum theory within physics. So what does that have to do with pigeons finding their way home? It turns out that pigeons and other birds actually use quantum mechanics in finding their way across the thousands of miles filled with mountains, oceans and countless obstacles that characterize their journeys home. Pigeons and other birds are actually thought to "see" the earth's magnetic field, though what it looks like to them, nobody knows. Recent work by scientists suggests that this sense of sight relies on quantum mechanics - that is, birds detect something happening in the eye at a subatomic level. Light striking the retina seems to stimulate chemical reactions that produce pairs of molecules with electrons that are "entangled," meaning they share certain quantum properties. One of those properties, called "spin," is affected by a magnetic field. That effect could tell the bird which way is north. Yet birds actually have a great many navigational tools at their disposal and they are incredibly resourceful. Decades of studies with frosted lenses, magnetic coils or scent deprivation show they use pretty much every clue available.
Perhaps the moral of this story is that the next time you see our feathered friends in flight or atop a tree and they are looking back at you, they may be seeing an aspect of you that we can only imagine. You might be serving as a signpost on a journey that they are taking back home. Wish them well on their journey!
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