Avatar Reflux, er, make that Redux

So at the trailhead last weekend, Murph was going on about finally seeing Avatar now that it's out on video.
Murph: "I saw it, but I must've missed something.  Why were people so crazy about this movie?  I just didn't think it was that good.  Did I miss something?"
Me: "Yeah, you missed something alright, the 3D part.  The rest was pretty lame.  But the 3D was cool, it felt like being there."
Well, that's my take and I still stand by my original review.  But if you want to see the nuclear option where the two reviewers twist their keys simultaneously, go check out LabRat and Stingray's, over at Atomic Nerds.  I dunno, maybe if I was forced to watch the 2D version while somebody jabbed needles into my leg I could work up a comparable level of loathing.  But I really don't think I could get it down on a keyboard with quite as much style.

J.J. Cale and Eric Clapton

Interview article found here.  Bonus: YouTube clip of them playing After Midnight, live.  Scroll down to the bottom.  Just freekin' amazing.

Ever want to tour Chernobyl?

Well, here's the next best thing: http://www.kiddofspeed.com/, a picture journal from a crazy Ukrainian biker chick who blasts in, takes snapshots – carefully! – and gets the hell out before she spends too long and gets cooked.  It's not that hot there.  At least, for a day of photographs and nuclear tourism, it's pretty safe.  A quick run through the radiation numbers she discusses indicates that a partial day is safe enough, a week would be noticeable but manageable, but a month starts getting into serious doo-doo.  Out around three months' stay and the doo-doo gets even deeper, six feet deep to be precise.
Weird place, reminds me of the worst parts of Katrinaland.  Except that people can live in Kartinaland without dying from it.  At least not directly.
Hat tip to The Atomic Nerds for posting this recently and reminding me of it.  I'd seen the site a long time back, but had dropped it somewhere in my mental slushpile.

Earth Day preparations in New York

*facepalm*

I... I just can't add anything here.

Such Hate

This guy Scott Merrill is just eaten up with it in this article.  
*CAUTION* graphic images of violence, including kicking and baseball bats.

Monetary Conundrum for the Week

Ever since I figured out that money was something deeper than the paper dollars Mrs. Moran paid me to mow her lawn back in Jr. High, I've thought that our central banking "logical money" system was pretty weird, even if it does sort of work.  Now some people are playing with quantum money schemes.


My first thoughts were "Oh great.  Now I won't know if I'm broke until I actually look in my wallet.  Uh, bartender, I'll catch that tab next week."  Or maybe pickpockets in the future would do their work by rubbing empty wallets against targets' back pockets or purses and letting the cash tunnel through.  Or something strange like that.


No, nothing so cool.  It's just mathemagicians playing around with quantum encryption schemes for the secure transfer of digital cash.  Still, pretty damn cool.

Entropy, Housework, and harnessing the Forces of Disorder to clean under the fridge

Got that lesson on entropy from yesterday?  Well, go re-read it because the test is next cleaning day.

Now let’s talk about dirt, disorder, and entropy.  I don’t know about you, but my household has a good working relationship with the Forces of Disorder (FoD).  A strong relationship.  A frequently disgusting relationship.  Now here’s the cool part: you can harness those forces to help keep your house clean!  Yeah, no kiddin’.  Listen up.

So let’s define the “temperature” of a patch of floor as the amount of dirt per unit area (square foot, square inch, square meter, doesn’t matter), and dirt is kind of like heat energy.  So a dirty patch of floor will have a higher dirt density – or “temperature” – than a clean patch of floor.  Now suppose the whole kitchen floor is dirty, but you don’t want to move appliances around to sweep under them.  So just sweep whatever’s easy, whatever you can get to, and harness the FoD to take care of the rest.  How?  Well, say that random wind and scuttling rats will redistribute whatever dirt is on the floor until it’s pretty much random, i.e., sort of even.  So you’ve swept the middle of the floor, but not under the fridge.  The entropy equation for any further random motion will look like:

dS = dH/T(clean floor) - dH/T(under the fridge)

Under the fridge is “hotter” – that is, it has a higher dust bunny density.  So for the disorder to increase (and we KNOW that is going to happen, given all those random breezes and scurrying rats), dirt will have to move out from under the fridge onto the clean floor.  Where it is easily swept up, with no appliance moving required.  Viola.  You’ve just harnessed disorder to help you keep house.

You may have heard the old saying “a clean house stays clean.”  Well, there may be a psychological aspect to that (aka broken window theory), but the real truth of the matter is that it’s just thermodynamics (dirtodynamics?) at work to increase disorder.

Next time: Doing your laundry like a supercomputer.

Bethel Trails Tato-Nut Ride

And it was a fun day in the woods.  More pictures can be found here.

Entropy Explained

[N]o one really knows what entropy really is, so in a debate you will always have the advantage.

– John von Neumann

So here’s a quick take on entropy.  It’s usually defined as dH/T – that is, change in heat energy (dH) divided by temperature (T).  Keep in mind a couple of things.  First, the temperature is absolute temperature, i.e., starting from absolute zero.  This means that in some sense, the temperature we’re discussing here is total average energy per unit of mass/stuff/whatever.  The second thing to keep in mind is dH is the amount of “energy in play” for a given heat transfer.  

OK, so the usual way to set up an entropy equation goes like this.  We have two “heat reservoirs” – think of them as big tanks full of hot water.  One is hotter than the other.  We're somehow going to let some small amount of heat energy (dH) flow between them.  In this simple example, it’s not enough to affect the temperature of either heat reservoir, because they’re that big.  (You can do the problem where they aren’t that big, but it takes calculus.  Not going there now.)  So we can write down the total change in entropy as:

dS = dH/T1 + (-dH)/T2

where: dS is the change in entropy, dH is the amount of energy transferred, and T1 and T2 are the temperatures of the two reservoirs.  The negative sign is on the last term because Reservoir 2 is losing dH of energy, while Reservoir 1 is gaining dH of energy.

Everyday experience tells us that heat will flow from the hotter reservoir to the colder reservoir.  So if T2 is the one losing heat here (remember that negative), it must be the hot one.  So let’s do some hand-waving math: if T2 > T1 (i.e., Reservoir 2 is hotter), then dH/T1 > dH/T2, and so the total change in entropy, dS, is always going to be greater than zero.  Another way of saying this is: entropy always Increases in a closed system.  (Closed?  Huh?  Whazzat mean?  It means in this simple example, heat can only flow between 1 and 2, it’s all insulated from the outside world, and there is no Resivoir 3.)

Here’s another way to get your mind around the concept: think of heat as money, and temperature as how rich someone is.  A $100 bill isn’t going to make much difference to Warren Buffett, but it will make a whale of a lot of difference to a starving undergrad.  So if there’s any mooching going on, who’s more likely do the mooching?  Which way will money tend to flow?

dS$ = $100/T1 - $100/T2

That’s right, T2 is “hotter” or richer, so it must be Warren Buffett’s wallet.  And once again, the entropy increases as the $100 bill changes hands.

But what IS entropy?  How can we think of it?  Statistical mechanics mathematically re-defines it as a measure of disorder.  In other words, in a closed system (here, two tanks full of hot water, insulated from the rest of the world) disorder always increases.

More on this as it relates to housework tomorrow.

Gojira

Finally saw Gojira, which was pretty good in a pulp-monster-noir kind of way.  Much, much better than the Hollywoodized version, Godzilla, King of the Monsters!, which is best described as silly.  Why in the world someone would re-cut a movie like Gojira and insert Raymond Burr is beyond me.
Ah well, time for my morning stroll.

Chopping the U.S.'s Only Current Spacecraft Development Program

Neil Armstrong says don't cut it.  We'll lose vital expertise and infrastructure for the long-shot hope that commercial launch services will eventually fill the gap, and in the meantime will be wholly dependent on the Russians for manned access to space.  Trashing a 10 billion dollar investment doesn't sit well with him either.
Buzz Aldrin says chop away and good riddance.  His thinking is that this move will free up money for other NASA priorities (good ones too: ISS operating funds, planetary science, and Mars mission planning), and spur private manned access to space.


My take: the both make valid points, but why isn't the damned thing flying already?  Yeah, I know: money.  But it's not like we had to – expensively – invent everything completely from scratch either.  Ten billion wasn't enough?  In constant 2005 dollars that's about 10% of what we spent on all of Apollo.  Most damming though is that it's been SEVEN YEARS since since Columbia crashed and the decision was made to go with Constellation.  That's longer than the initial "go" for Mercury to fully operational Gemini spacecraft.  The whole Constellation program reeks of development hell.


Here, go read up on it a Wikipedia (and keep going from there) and make up your own mind.

How to Work a Physics Problem in Four Easy Steps

Here’s the first class lecture from my former teaching days in a nutshell.  I’d grade on four things (hold up fingers) roughly equally, be they homework or test problems, and I’d tell the students to break the work down the same way.

1. Identify the equations from the text that seem relevant to the question.  What we were just talking about in class should give a big hint.
2. Start setting up the problem.  Identify what in the equations from Step 1 are given, what is being asked for, what the missing pieces may be.  Maybe sketch out the physical situation, but at least set up a coordinate system.  Go get more or different equations if there are loose ends, spare pieces, or missing parts.  Underlining the symbols in the equations for given information in green, the target unknown in red, and stuff to be gotten from other equations in blue can really help with this step.
3. Do the math.  Not with a calculator, solve for the answer analytically, pencil-and-paper style, keeping everything in symbols.  You want to end up with the variable you’re solving for neatly isolated so that you can plug in numbers and have an answer pop out.
4. Plug in the numbers and check your answer.  Is the value reasonable?  Or are you predicting that it will take 3600 seconds for a coyote to to fall off a 20 meter high cliff?  Take a moment to explain your cross-checking on the answer.

1-2-3-4, easy for the students to lay out, easy for me to grade.  I’d give an example here, but I’m too tired to sort out math symbols on blogspot right now.  “Left as an exercise for the student” as the saying goes.  Naturally, this is 1-2-3-4 is only a beginner’s technique.  Too frequently in the course of research, just coming up with the equations for Step 1 is the real problem.

Rancho Costa Nada

In short, the author of this literary masterpiece moved out to a patch of nearly free (well, $300) uninhabitable desert, built a shack, and started doing as he damned well pleased.  Model rocket launching in front, .22 & .303 ranges out back, extended morning walks anytime the mood strikes him.  Apart from the broiling heat, freezing cold, utilities powered by his Geo Metro's 12V battery, and his chief social interaction consisting of rambling chats with "The Demented Vet" down the road, it sounds pretty sweet.


Well, it's an option.  Needs a mountain bike though.  Not quite ready to make the jump, personally.

Klunkerz, the movie

Just a straight-up documentary about the origins of mountain biking.  Highly recommended.  You can find more about it here.

Machine Soul

The machine soul of a mountain bike is defined in this old essay by John Gurklis in Dirt Rag: "Machine soul is acquired as the rider's mental energy becomes infused into the frame members of the bike."


After almost ten long years of riding, my Trek STP (picture here, scroll down) has a respectable helping of machine soul.  And now after swapping out the stem, the cranks are the only original component left on the bike.  Currently on the third back wheel, second fork, fourth rear deraileur, second set of brakes, umpteenth chain (I'd estimate somewhere in the neighborhood of seventeen), the carbon frame is going strong.  We'll see how much longer this soul machine keeps going. This bike always fit well, but now after replacing the stem (due to long-term stress, didn't want to keep taking chances on the old hunk of aluminum) with a slightly shorter one, it fits even better.


ps: The coyote mojo is on its fourth bike.  But that's a separate matter.