Gabriela Barreto Lemos
Schrödinger's cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935. It illustrates what he saw as the problem of the Copenhagen interpretation of quantum mechanics applied to everyday objects. The scenario presents a cat that may be simultaneously both alive and dead, a state known as a quantum superposition, as a result of being linked to a random subatomic event that may or may not occur. The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics. Schrödinger coined the term Verschränkung (entanglement) in the course of developing the thought experiment. (source)
While quantum mechanics is tough to get your head round, you probably know about Schrödinger's poor old cat: left in a box, both alive and dead at the same time. Well, now there's a picture of the ill-fated feline.
Well, kind of. What you're actually looking at is an image created by quantum weirdness. The image above was created using entangled photons and a cat stencil. The odd bit? The photons used to create the image never went anywhere near the stencil, and the photons that did hit the stencil never went anywhere near the camera. Wait, what? New Scientist explains:
When two separate particles are entangled, measurements of their physical properties are correlated, and they effectively share a single quantum state. To [make this image], the researchers created yellow and red pairs of entangled photons. The yellow photons were fired at the cat stencil, while the red photons were sent to the camera. Thanks to their entanglement, the red photons formed the image of the cat because of the quantum link to their yellow twins. The silicon stencil was transparent to red light and the camera could only detect red light. This demonstrates that the technique can image objects that are invisible to the detected photons.
So, quantum physics never stops seeming weird. But at least now we've found that damn cat. [Nature via New Scientist]