Measure Cow Gas - Bizarre Eye Blind Spot

Is the problem of trying to collect and measure gas emissions from livestock (or maybe your in-laws) keeping you awake at nights? Have you ever wondered exactly how much energy cow burps emit? Now your curiosity can be satisfied with the 1993 patent of the 'System for Measuring Metabolic Gas Emissions From Animals"! Designed to measure how much energy free-roaming livestock actually use, this device will help identify the feeding systems which allow the most efficient use of energy for the health of the cow.

But wait! The device is fun and easy to use! First feed the subject the tube which acts as an internal tracer. Attach the end of the tracer tube to the inflatable collar placed around the animals neck. With every breath, metabolic gas samples are collected and analyzed. Hey, who said bovine belches aren't fun? Click here to check out the latest science info on Cow Gas!

Disappearing Dot

This is bizarre... there is a blind spot right near your centre of vision. If you don’t believe me, try this experiment.

1. Draw a black dot on a piece of paper. Write the numbers 1 to 7 to the right of the dot.

Make the dot about 1cm in diameter. Space the dot and the numbers about 1.5 cm apart.

2. Hold the piece of paper about 20 cm from your nose. Close your right eye. Now look at each number in turn but pay attention to the dot.

The dot will ‘disappear’ when you’re looking somewhere between 2 and 5. The next step is even more amazing!

3. Draw a red line though the dot and numbers. Repeat step 2 to make the dot disappear again.

Amazingly, the line appears unbroken when the dot disappears!

4. Diagram of a Human Eye

Here’s a simplified picture of your eye to help understand what’s going on.

5. Photograph of a Human Retina

This is a photo of a human retina (mine in fact). You can see the optic nerve and blood supply entering through the bright area. This area is called the optic disk. The slightly darker patch to the right of the optic disk is called the fovea.

Note: this photo was taken by an optometrist using a special camera.

what's going on?

The back of your eye is called the retina. It's covered in millions of special cells called photoreceptors. Photoreceptors convert light energy to tiny electrical signals, which are then sent to your brain along tiny nerves.

All the nerves inside your eye are neatly bundled together into one big cable called the optic nerve. The optic nerve exits the eye along with the retina's blood supply through the optic disk. The optic disk is the bright area in the photo of the retina above. You can also see the blood supply (arteries) entering through the optic disk.

Because the optic nerve itself is not sensitive to light, the optic disk is a blind spot. The black dot you drew 'disappears' when it is focussed onto the optic disk.

Now the optic disk is very close to another important part of your retina called the fovea. The fovea is the dark patch just to the left of the optic disk in the photo. When you look directly at an object, its image is focused onto your fovea. This area has more photoreceptors than any other part of your retina and is where you see sharp detail.

Being this close to your fovea, you might be wondering why we don't usually notice this blind spot? It's easy to assume the brain uses the right eye's view to fill in the left eye's blind spot and vice versa.

But even with one eye close, you still don't notice your blind spot! Remember what happened to the line you drew through the dot? Somehow, your brain looks at what it sees around the blind spot and then amazingly fills in the blanks so everything looks normal.

That's a good thing too... just imagine how annoying a big dark spot in your field of vision would be. It's also a great reminder that our sense of vision is a partnership between the eyes and the brain. So make sure you look after both!

To find the blind spot in your right eye, turn the paper upside down so the dot is to the right of the numbers. Also try holding the paper a bit further away from your eyes... can you explain why you now have to look at a different number to make the dot disappear?

Sources : Science Tricks, Absurd Patents

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