human eye adapted luminance range contrast ratio

The eye adapts across a huge range of brightness

100-trillion-fold

By adapting to changing light, the human eye can work across brightness levels spanning roughly 100 trillion times from dim to bright. At any one moment, however, the range it can handle is much smaller.

How strong pain feels and how unpleasant it feels are not the same thing

Pain has more than one part. A sensation can feel physically strong while its unpleasantness changes separately. Excitement may reduce both, while suggestion or a placebo may reduce how unpleasant pain feels without changing its physical strength as much.

The seafloor records Earth’s magnetic flips like a barcode

New rock forming on the ocean floor records the direction of Earth’s magnetic field. As the field flips and new seafloor moves outward, matching magnetic stripes form on both sides. These stripes became strong evidence that the seafloor is spreading.

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human eye adapted luminance range contrast ratio

The eye adapts across a huge range of brightness

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