ScienceIQ.com

When Do We Encounter Ionizing Radiation In Our Daily Lives?

Everyone who lives on this planet is constantly exposed to naturally occurring ionizing radiation (background radiation). This has been true since the dawn of time. The average effective dose equivalent of radiation to which a person in the United States is exposed annually is estimated to be about 350 millirem. (A millirem is a unit that estimates ...

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IonizingRadiation
Geology

Salty Remnants At Death Valley's Badwater

Beneath the dark shadows of the Black Mountains, a great, extraordinarily flat expanse of shimmering white spreads out before you. You are at Badwater, at -282 feet it is the lowest spot in the ... Continue reading

SaltyRemnantsAtDeathValley
Physics

Torque

A force may be thought of as a push or pull in a specific direction. When a force is applied to an object, the object accelerates in the direction of the force according to Newton's laws of motion. ... Continue reading

Torque
Geology

Was That The Big One? Depends On How You Measured It.

The severity of an earthquake can be expressed in terms of both intensity and magnitude. However, the two terms are quite different, and they are often confused. Intensity is based on the observed ... Continue reading

TheBigOne
Biology

Monkey See Monkey Do: Mirror Neurons May Lie At The Root Of Language

Self-awareness, the ability to infer the mental states of others, and language are considered uniquely human cognitive skills. But they didn't spring into the human brain out of nowhere. A ... Continue reading

MonkeySeeMonkeyDo

Now You See It, Now You Don't

EMRadiationWhat we call light is simply a narrow band of electromagnetic radiation that our eyes are sensitive to. This radiation enters our eyes and is conveyed to the brain by the process we call sight. While the mechanics of seeing is quite complex, the process of seeing is, in a different sense, quite extraordinary. Here are two examples.

Have you ever used a telescope to view a distant object and realized that the image you are seeing is upside down? A telescope with convex lenses creates an upside down image. Your eyes do the same thing. As light enters your eye, it passes through your cornea and is focused by your lens onto the retina, which contains light-responsive cells called rods and cones. Because it works much in the same way as a telescope, the image projected on your retina is upside down. The optic nerves in the back of your eyes conveys this upside down image to your brain. But when you look at your cat, he's not walking on the ceiling. Thankfully, your brain does the switch for you, and flips the image.

Each of our eyes has a blind spot, a place on our retinas about the size of a pinhead where there are no rods or cones. Our blind spot is the place where our optic nerves exit the eye and connect to our brains. But we don't usually notice this blind spot. That is because our brains fill in the information for us. We think we see what we should be seeing. The trick, of course, is that as we move and focus our eyes, the blind spot is a moving target. Our brains can make a pretty good guess as to how to complete the picture of what we are looking at. To see your blind spot, follow the link to the larger image of the image on the right. Close your right eye and focus your left eye on the purple soccer ball. Now slowly move your head closer or farther from your computer screen. Can you make the orange soccer ball disappear? Then you've found your blind spot.