Saturday, October 24, 2015

Why Can't We Taste Spoons?

A Short Story of Stainless Steel and Cheerios That Don't Taste like Pewter


Technology



One relatively recent innovation that not many people think about is the fact that we can't taste spoons. Think about it. That is extremely convenient. Pewter spoons have a taste, steel spoons have a taste, spoons hewn from wood all have a flavor they impart on everything you eat. It wasn't until stainless steel that was had truly tasteless utensils. Stainless steel was not only one of the most important alloys developed, but it almost wasn't discovered by a person called Harry Brearley.

Brearley was a metallurgist working in the early 1900's, who was tasked with finding an alloy better suited to make gun barrels. In his shop, he would make alloy after alloy with many different metals, and after testing them for hardness and gun barrel suitability, he would cast them into a corner of his shop where they would pile up for weeks before he found the time or will to discard them. As he was disposing of one such pile of rusty gun barrels, he noticed one that was still as bright and flawless as the day he produced it.

Working backwards, he was eventually able to trace back that gun barrel to an alloy of steel and a substance called chromium. In a plain steel gun barrel, the steel reacts with oxygen in the air, creating iron III oxide, better known as rust. The rust layer will eventually peel off, exposing more bare steel underneath, which then undergoes the same process. This is why rust can eat through metal so effectively. Not so with the alloy of steel and chromium. The chromium in the metal interacts with the oxygen in the air to create a chemically inert substance called chromium oxide. This layer of chromium oxide that forms on the surface of the barrel does not peel away, and effectively stops the process of rusting. Best of all though: chromium oxide is non toxic and does not have a taste. Hoorah! Tasteless utensils!




The reason soup is so delicious


Cheers, 

     - Scott


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Linkstorm

This is just a long list of interesting things around the internet I've run into. Enjoy.




A great explanation of how objects orbit each other, rather than one orbiting another


An visually amazing video envisioning a future human presence in space, along with commentary



Here is a video showing bee development in great detail from NatGeo. (Warning, bugs)



This guy decided to make a working version of Thor's HammerMjölnir that you can only pick up if you're worthy.



The cutest little self-folding origami robot



A parody of "Space Oddity" using only the ten hundred most common words. (Like this webcomic)



Clickbait! Men's fashion from the 70's you "won't be able to unsee."



Where does fortune telling cross into harmful territory? This article talks about one case that absolutely does



Why every state flag is wrong. Just wrong



One of the coolest sinks I've ever seen



The relationship between humans and machines, through chess.



Here is what the ARES III mission site from the book and now movie "The Martian" actually looks like.



The making of the worlds most complicated watch



This is the best video I've seen of an exoplanet orbiting a star.



An interesting Star Wars fan theory



An interesting take on the crossword puzzle, no clues





Cheers,

      - Scott



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Tuesday, October 6, 2015

How Big is the Death Star?

I recently became curious about the death star. It’s fictional, I know; but I kept asking questions: What would it take to supply such a large space station? What about to build it? Does it have enough gravity to walk along the surface? Come along down this rabbit hole with me.

Image: JMAS

Note: the Death Star I chose to look at in this article is the larger Death Star II (160 km in diameter vs. 120 for Death Star I). Death Star II is the one Lando Calrissian destroys above the forest moon of Endor in Return of the Jedi, not the one that the Luke destroys in A New Hope. 


The Physics

I started this journey by looking up the specs of the Death Star and calculating its volume, mass, surface gravity etc… I soon found an oft-quoted stat online that mentioned the Death Star’s volume was “17.16 quadrillion cubic meters.” This surprised me because the answer I got was an order of magnitude lower. After looking into it, I found out this calculation had been done using 160 km as the radius, not the diameter, yielding an incorrect answer. Below are the correct stats for the Death Star:

Diameter* ………………..……… 160 km
Volume …………………..………. 2.1 quadrillion m3
Mass** ………………….…………1.6 quadrillion kg
Surface gravity …………………. 0.0002 % of Earth
Total Crew* ……………………… 2,471,647 (This is strangely specific)
*According to Wookiepedia
**Assuming 1/10 of the volume is steel


Earth and the Death Star to Scale



The first thing that struck me that the Death Star is small. I know the movie compared the Death Star to a "small moon," but the Death Star is much smaller than I imagined, on the scale of Jupiter's tiny moon Janus, or, appropriately (it looks just like the death star), Saturn's moon Mimas.

The second thing that caught my attention was the very low surface gravity. If I was out walking along the surface of the Death Star, I would weigh about the same as a large grain of sand. If I had one or two friends with me, we could lift the Titanic off the surface. If you could get enough traction, you could simply walk into orbit (1.15 m/s). The Death Star is massive for a space station, but because there are a lot of empty spaces, it just doesn’t have that much pulling force.

The Crew

What about the crew? How much do they need to eat? How much waste needs to be disposed of?

First off, let's look at butter. Butter is the one of the most calorie rich foods out there, so if we assume everyone just eats butter, we'll get our most conservative estimates.


A stick of butter contains about 800 calories, and an adult human needs a little less than three sticks of butter to survive for a day (do not try). By volume, about 10 people need a liter of butter per day. This means that the Death star requires about a quarter-million liters of butter per day to feed its personnel. That's about 7 Boeing 747 cargo planes' worth of butter, which seems manageable. You would need another 2 and a half planes for the water, but overall, that seems pretty reasonable.

According to Wookiepedia, the Death Star has a 3-year store of food (assuming Earth years, even though Earth is in a faraway galaxy in the distant future), which in butter terms is about 1 Hindenburg.

Overall, no real problems arise when stocking the Death Star with food and water, even if the calorie density is much less than that of butter.

What about waste? One average US citizen in 2008 produced about 2 kilos of food per day. On the Death Star, this equates to 5 million kilos over the whole population, or less than half of the daily trash output of New York City.

A good way to think of the Death Star is about one "Chicago" of people (new unit). The Death Star needs about the same amount of food, and generates the same amount of waste as a large city.

The Death Star has about 1,600 Dropships that, if operated around the clock, could supply food and water to the entire Death Star. Waste could simply be expelled into the atmosphere of the forest moon of Endor. Then it's the Ewok's problem.


Image: David Kingham

The Cost


The answer to the question of how much the Death Star would cost to build started with flawed numbers, so I've redone the calculations.

The current (Sept. 2015) cost of steel is 140 US dollars per tonne. To put our weight in tonnes from kilos, we can just knock off three zeros, getting us 1.6 trillion tonnes of steel, coming in at 224 trillion dollars just for the steel. To lift this amount of steel into orbit would cost 35 quintillion dollars and take 70 billion US Shuttle flights. and to avoid collapsing the global steel market (and to make things cheaper), let's just grab an asteroid with that amount of steel and hollow it out to make our death star.



16 Psyche

16 Psyche should do nicely; it's mainly nickel and iron, 200 km across, and we could find some carbon and smelt steel to make our Death Star. That should keep the total bill under a few trillion to get the raw materials together. As far as turning these elements into the Death Star, that's pretty much out of reach with the planet's current resources.

Overall, it seems that most aspects of the Death Star are out of our reach, and without a bent for galactic domination, I think we should leave the construction of Death Stars to galactic empires in the distant past, and we should focus on, say, getting to Mars. That's a good starting point.


     Cheers,
   
          - Scott


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