Question #5 Why do people poop corn?

From Zach on Facebook.

I was waiting for a question like this to come up. I am never disappointed.

Before we talk about why we poop out corn lets talk a little about seeds and the human digestive system.

An individual kernel of corn is a seed. Each ear of corn has many many seeds on it. Here is a diagram of a single corn kernel.

From http://www.corn.org

 We can see inside is the germ (or where the corn plant will develop from) and the starch/gluten which will serve as food to the young plant while it develops its first roots and leaves. Then we have the hull and fiber. The hull and fiber are not digestible by most animals, including humans.


There are several stages of digestion. The first is mastication or chewing. When it comes to corn this is a very important step. Chewing breaks open the individual kernels and exposes the starch and gluten which we can digest. If the kernel is not chewed and swallowed whole then the hull will be mostly unaffected by our digestive system the rest of the way through.

The reason our digestive enzymes and the stomach acids don't breakdown the improperly chewed (or swallowed whole) kernels of corn is that the hulls are cellulose. We, humans, don't have a digestive system that can break down cellulose so the corn kernel passes through the digestive system.

Having whole kernels of corn in your poop means that you did not spend enough time chewing your corn before swallowing it. The unchewed kernels are expelled in the feces (poop) with the hulls still intacted.

One side note..... there is an advantage to the plant for humans and other animals to poop out their seeds whole. Most seeds have a cellulose hull or coat that allow them to pass through the digestive system of most non-ruminant animals unless they are chewed. What this does is mix those seeds in the feces. If we imagine back before toilets or outhouses humans were doing their bathroom duty in fields or behind trees like the rest of the animals. The human or other animal would ingest a seed and then when they would go to the bathroom the seeds would be embedded in the feces. The feces provides nutrients (instant fertilizer) and water. An added bonus is that most animals will not dig in feces to acquire those seeds so the passing of the seed also offers a measure of protection to the seed from being eaten by something that will chew it better or can digest it.

Question #4 Why is there so much space between things in the universe?

From Zach on Facebook.

This question is directly related to the Metric Expansion of Space or the increase of distance between objects and particles in space. To really get a grip on this topic lets go all the way back to the Big Bang then work forward.

The Metric Expansion of Space from Astronomy Magazine and NASA: http://cs.astronomy.com/

At the moment just prior to the Big Bang all the matter and energy of the universe was in a single point. Technically it had not volume it was crushed in so tiny. At the moment of the Big Bang all of this energy and matter flew out of this volumeless point at speeds at (or some speculate even faster than ) the speed of light. Now all this matter is flying away from this point and starting to spiral and form early gas clouds and accretion disks and so forth. However, even these larger items that are forming are still being acted upon by the energy that came out of the Big Bang so they are being shoved away on all directions at the speed of light.

Gravity can hold these moving objects together. For example, every star in the Milky Way galaxy is being acted on by this initial Big Bang force, however, the gravity between all those stars keep them moving as a group. Think of it as a bunch of people swimming in the ocean. If a huge wave comes in they'll be pushed around in different directions and away from each other. If those swimmers are holding hands (the hand holding is gravity) then they will be moved as a unit by that big wave.

The Universe is 13.7 billion years old +/-. For these 13+ billion years everything has been moving at the speed of light or near the speed of light at least.

The speed of light is 299,792,458 m/s. Let's convert this term to meters per year (m/yr) so that we can compare it to our 13.7 billion years.

After we cross out all of our units we are left with the following calculation which will give us meters per year.

299,792,458*60*60*24*365= 9.454255 * 10^15 or written out it would look like this....

9,454,255,000,000,000 m/yr.

If you are not comfortable with meters that would be 5,874,601,701,065.775391 mi/yr.

That's a lot of distance to cover in a year. To put it in perspective it is 10 million times the distance from the sun to Saturn. This should start getting to the reason why things in the universe are so far apart.

While doing these calculations why don't we look at how far a particle, say a hydrogen atom, may have moved from the Big Bang if it were present at the exact moment of the bang and traveling away the entire time.

5,874,601,701,065.775391 mi/yr * 13.7 billion years. = 80,482,043,000,000,000,000,000 miles
or... 13,690,622,873.69648 light years.

How do we know this calculation makes sense?

We know that our hydrogen atom was traveling at the speed of light (i.e. one light year per year) for 13.7 Billion years. Our answer for how far it traveles is 13.7 billion light years (if we round.)

So what does this all mean? That means that 13.7 light years is the farthest distance two objects can be from each other. i.e. one object on one end of the universe to another object on the exact opposite side of the universe. Any distance smaller than this is a possible distance between two objects somewhere in space.

Let's take this back to something more concrete. This Hubble article and video explains it without all the math.

This NOVA article covers it as well.

An awesome Visible Universe poster from National Geographic. The timeline at the top may be very helpful.

Question #1: Exactly how much of the color spectrum do humans really see?

This question comes to us from Flexcia on FB.

The first thing we must examine is the question. There is a common misconception that the full electromagnetic spectrum and color spectrum are the same. The color spectrum is, by definition, the visible light or the colors we can normally see. The electromagnetic spectrum is the visible plus other parts of electromagnetic energy. (see the image here.)

Electromagnetic radiation occurs in waves. The nanometer (nm or 10^-9 meters) measurement is how far it is from one hump of the wave to the next. This is called wavelength. Higher numbers mean there is farther distance between the waves and a higher energy, slower moving wave. Higher energy has shorter wavelength.

Here is a way to think about wavelength.

So, imagine you are holding this rope and the other end is tied to a tree. If you want to do slow waves you can move your arm slowly but if you want more energy in the waves you have to really move your arm with a lot of energy. This can help remember whether short or long waves have more energy.


Humans vision is limited to the visible light between 400-700nm. However, animals can see in other wavelengths. For example, birds and bees can see the visible spectrum and ultraviolet (UV) portions of the scales. Snakes and some other animals can sense the thermal infrared (IR) portions of the spectrum. Spiders only see green and UV. So there are all types of vision out there among animals.

Back to Flexcia's question. What part can humans see? The visible spectrum is our limit but there are millions of colors within that spectrum. Every color you've ever witnessed in a movie, a video game clothing, nature, all those colors are all in the visible spectrum.

Within that spectrum of visible light some individuals have more visual acuity. This means that some people can distinguish more colors than others. At the extremes there are things like red-green colorblindness where individuals can not accurately distinguish between red and green light wave lengths. The other end is those who have hyper-acuity. Recently a woman was discovered/found that has tetrachromat. Tetrachromat is the ability of being able to distinguish between more colors than the average person. If you want to test your own abilities to distinguish colors you can give it a try here.

While we are on the subject of seeing we should take a moment here at the end to discuss how we are seeing those colors. Most color we see is reflected light. Well what does that mean? Here's the best description for the process.

Imagine you are looking at a green leaf of a tree. Sunlight (which contains all the visible light colors) comes down and hits the leaf. Trees absorb light energy for photosynthesis. Tree leaves absorb all colors except green light. This green light reflected from the leaf and enters our eye. Because only green light is entering our eye that is the color we see. Leaves are green. Well, what about in the Autumn? Tree leaves are other colors. This is because of the change in the light that a tree is using.. absorbing.. as it prepares to go dormant.

Now, let's apply this principle to other things. Look at your shirt or a nearby object. Whether you are outside (in the sunlight) or inside (under white artificial light) all the visible spectrum colors are being produced by the light source. The item you are looking for is absorbing all the light colors except the one you see. So if your shirt is blue... it is absorbing all the visible colors EXCEPT blue.

If we expand this idea we can relate this back to electromagnetic radiation. Imagine it's a very sunny day. You spread out two blankets in the sun.. a black one and a white one. We all recognize that the black one will be hotter to the touch after being in the sun. Why?

The light we see is white. That means in order to perceive an item as white it is reflecting all the visible colors. None of the energy from those light waves are being absorbed by the fabric. (remember energy often creates heat). The black fabric though is absorbing all the colors. Technically, none of the light waves are being reflected to our eyes. The black fabric is absorbing more energy and therefore is hotter to the touch.

What about our computer screens? This is not reflected light. Instead of reflecting light from our monitor the monitor is projecting a certain color of light produced by the mix of pixels and their colors. High definition TVs often have more pixels per inch on the screen of the TV and more pixels per inch on the tape or video taken. This allows for more colors that give us a feeling of a higher depth or definition to the image.

I hope this answers your question Flexcia.