Speed of DARKNESS !!?

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      we all konw about the speed of light, First measured by Danish astronomer Olaus Roemer in 1676, it was Albert Einstein who realized that light sets an ultimate speed limit for our universe, of 186,000 rip-roaring miles per second (299 337.984 Km per sec) .

                 But while the immutability of lightspeed is drilled into physics students at a young age, Einstein’s laws also state that all motion is relative, which got us thinking: what’s the speed of light’s nefarious doppleganger, darkness?


The speed of dark? The easy answer is that it’s just the speed of light. Switch off the sun and our sky would go dark eight minutes later. But easy is no fun! 

        For starters, what we commonly call the “speed of light” is the speed of propagation, and that’s not always the deciding factor. A shadow swoops across the landscape at a speed governed by the object that casts it.
     For instance, as a lighthouse beacon rotates, it lights up the surroundings at regular intervals. The ground speed of its shadow increases with distance from the lighthouse.
       Go far enough away and the shadow will wash over you faster than the propagation speed of light.  All the speed of light means in this case is that there’s a delay: if the lighthouse points toward you at 12 o’clock, you will see the flash a little later. 
     Darkness isn’t a physical category, but a state of mind. Photons hitting, or not hitting, retinal cells may trigger the experience, but do not explain the subjective experience of darkness, 
    Our conscious experience changes from moment to moment, but the individual frames of that experience are timeless. In that sense, darkness has no speed.
And what about speed in general—is there such a thing? It presupposes a framework of space, and scientists see phenomena in quantum physics where spatial concepts seem not to apply—suggesting, to some, that space is derived from a more fundamental level of reality where these is no such as thing as position, distance, or speed. 

:- George Musser

Contributing editor for Scientific American and Nautilus magazines, author of Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time—and What It Means for Black Holes, the Big Bang, and Theories of Everything and The Complete Idiot’s Guide to String Theory

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