Mailing Fish, or "Why you should care about Styrofoam."

I was approached with a seemingly simple question today:

How would I send frozen foods to my significant other in Afghanistan without them thawing on the way there?

My initial thoughts ran to refrigerated cargo services, or having a store in a location closer to Afghanistan ship it a shorter distance... but none of these solved the whole problem of getting it to an APO. So while I'm not sure my final solution will work for an ACTUAL package trying to make it through ACTUAL base security (I'll wait for one of my military readers to comment), I can virtually guarantee that food shipped in this method will remain frozen quite nigh on indefinitely. Or at least a week, whichever comes first.

First, some background - I LOVE the little cheap one dollar "we're going fishing" rounded-corner Styrofoam coolers. They're a dollar.

Doing a quick google search for a picture of such a cooler, I can't find one - only these:

Which might work, but I get mine at a local Roses department store. For a dollar. Go cheap or go home ;-)










Sure beats the hell out of these, though they might be a better choice when actually shipping something to an APO, since it's "real" packing material.

So there comes a point here where science applies, and I think I'll choose to make that point right about... now.

There's a very simple relationship between the temperature of a body, the temperature of its surroundings, and how quickly the two temperatures approach one another. If the body is cold, then the surroundings lose heat to warm it up, and vice versa.

Observe:


What we have here is an insulator and a conductor - since the heat of the room flows easily into the conductive plate, it passes immediately into the ice and melts it. The insulator obviously, and by definition, obstructs the flow of heat, and so the second ice cube is barely injured in the time it takes the first to completely melt.

This is direct conduction, but as you know, air is all around us - when air, or any fluid, takes heat away from an object, we call that process convection.



As you can see here, the candle flame causes a current of air to rise up as it is heated, carrying heat away from the flame. In our case of an ice cube or frozen food, the air current would be downward, but you can see the basic concept - air will be set in motion, bringing more warm, room-temperature air into contact with our food. Not a good prospect for keeping it frozen on a trip of several thousand miles!

So, our goals are clear - keep it out of contact with the surroundings by placing it in a non-conductive container, and seal the container so that convection doesn't carry heat away either. There is one more mechanism of heat loss (or in our case, gain) - radiation.

Here, we see the use of a thermal camera to visualize the radiated heat from objects in the form of infrared light. Notice the otherwise black trash bag is completely transparent at these wavelengths!



So since we want to block heat from entering our container, but plastics seem to be nearly invisible to infrared radiation, and we should avoid conductors, but metal (the aluminum mirror) seems to reflect infrared radiation well, what are we to do?

Aha! We combine the two! Yessir, your common everyday "space blanket" is made from aluminized mylar, developed initially as a thermal barrier material for the space program. Other metals have been used, like gold, but the principle is the same, with a thin layer of metal vapor-deposited on a nearly perfectly smooth film of plastic, resulting in a mirror that reflects upwards of 98% of the incident infrared radiation hitting it!

So basically, with a bit of insulation, a radiant barrier, and a good seal, you can keep something warm, or cold, for a very long time. This, by the way is exactly how a Thermos bottle works. Just a double walled container with vacuum pulled between the walls, and the insides are vapor coated with aluminum, just like the space blankets, so they reflect heat, and the vacuum is about the best insulator you can get. With a tight fitting top, there's no convection to move air about the contents, and you're only losing heat through the cap itself and the wee little bit of material that connects the inside and outside walls along the cap threads.

Another victory for science, and another hot meal, or cold pre-meal, anytime you want it.

A new Blog to peruse...!

Thinker Says What?: Post Irene: I can't help but to ponder after the storm about the classic behavior of human kind & I am reminded of the story of the ant & the grasshopper...

mathematics video delayed

We are currently preparing for the first hurricane of the season to threaten the East Coast. Hope Irene stays out to sea, but in the unlikely event she decides to lay the smack down upon us, we will be posting our mathematics video sometime at the beginning of next week. I must say, it's amazing how many little things wind up in a yard just before a hurricane - rakes, tools, a can of gasoline for the lawnmower. So I'm spending the afternoon tidying things up so nothing flies around and smashes someone's windows, or my solar panels.

Be safe this weekend, and we'll see you on the other side ;-)

THE SUN TODAY: 21 August 2011 - COMET BURNS UP IN SOLAR ATMOSPHERE

Saturn's E-Ring, and the Zodiacal Light

In this photo, shamelessly stolen from a friend's Facebook post, Earth is visible in the upper left portion of Saturn's outermost ring, or the E ring. Apparently this ring isn't all that visible except when Saturn itself blocks out the sun during an eclipse. Those don't happen on Earth, since Saturn is WAY out in the outer solar system cruising along it's nearly 30 year orbit.

Also visible in this photo is the faintest hint of something called the Zodiacal Light. Check the Wikipedia page for plenty of awesomeness, but in short, it's the dust cruising around the solar system on it's way from places like the Oort Cloud, Kuiper Belt, and random asteroid, planetary, and cometary impacts, towards the sun itself.

You'll notice that the glow gets rather bright just outside this E-Ring in the photo, then fades away gradually as you get further from Saturn in the image. The reason for this is twofold - first, Saturn plows through the solar system mopping up any debris that gets near it - it's gravitational field is quite efficient at either capturing (ring material), or ejecting (bye bye) comets, asteroids, and even dust particles, since gravity works pretty much the same no matter your mass. This leaves a distinct Saturn-shaped hole in the dust, and with no dust, there's no reflected light to smack the CCD's on Cassini, so the area around Saturn appears dark.

The reason for the gradual fall-off as you get further from Saturn is really quite simple. Go driving in fog sometime. Actually, don't, just look at this:

Light Painting (flashlights in fog)

You'll notice that these totally bangin' photos all show a flashlight in fog - as you get further away from the beam's center line, the angle between the light beam's center line and the particles starts to get quite oblique, until the light's basically being reflected back at the flashlight. Also, since it's a flashlight, there's a reflector which gives you an actual beam, but it works the same way in reverse when we think of our eye, or a camera, looking towards the Sun - all that dust beyond a few dozen degrees away from right smack in front of us just isn't reflecting a ton of light towards us - most of it's going off at a slightly glancing angle and passing us by, just a few degrees away.

So, there's your quick primer on Zodiacal Light, all stimulated by a picture of Earth from just beyond Saturn.

Have a nice weekend!

Speed, Acceleration, and Why Math Education Fails in the U.S.

I decided to start this blog to provide a modicum of online tutoring, and maybe make a few cents on the side with a little help from Google. In the time it took me to set up the Facebook page, all the "Like", "Subscribe", and "Share" widgets, settle on a background and layout that didn't look too goofy, I wound up speaking to several relatively intelligent friends about math-related topics.

I now have a headache.

So, in an effort to alleviate that headache, I'm starting a bi-weekly series of mixed-media episodes to illustrate how obscenely simple Mathematics can be.

Please subscribe and look for my next post, "From Counting to Calculus in Five Minutes", where I cover about 60,000 years of Mathematics advances in roughly 600 seconds. Bonus: You'll actually understand it!

We're still putting things together, so if there's a specific topic you want us to cover, feel free to post a suggestion in the comment section!