Happy 4th Of July

I promised you all a demonstration of my cousin and I’s firework weapon “The Awesome Possum”.  We were kind of crazy kids, chasing each other around open fields with these things.  As you can see though, they’re so inaccurate it’s rare for anyone to even get hit, and even when you are hit, bottle rockets aren’t anything to worry about if you’re wearing proper eye protection.  This video features a bigger “possum” weapon, though I will later demonstrate a smaller launcher which is easier to load and fire.

Happy 4th of July.

AP Barrel

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The Possum Will Rise Again

Do any of you have childhood memories of things which were absolutely amazing at the time, but then you went and relived those moments as an adult, only to find they weren’t all that great in retrospect?  I’ve had that happen many times.  As a kid, I absolutely loved it when Mom would make hamburger helper.  I begged my Mom to make me some again, and well, it’s not horrible but it’s nothing to write home about either.  I also remember a time when my parents took me to this water park with a big water slide.  I decided to revisit and as I made my down the blue pipe, it just wasn’t the same.

I wonder what changes in the adult brain?  I’d love to feel that excited about anything again.  When I was a kid, all you had to do was dangle a piece of watermelon Airheads taffy in front of me and I’d be ecstatic, grinning ear to ear.  Now I have enough money to walk into the store and buy entire cart-fulls of candy, but all I’d end up doing is nibbling on a bit of it and say, “Meh.”  Actually, I shouldn’t say that.  I absolutely love chocolate.  Milk chocolate.  Dark chocolate.  Doesn’t matter.  I love chocolate.  I actually like that more than I did as a child, and that’s saying something.  I’d likely end up gorging until I got too sick to eat anymore.  Anyway, where was I?  Oh yes.

With the fourth of July around the corner, I found myself remembering all of the firework wars I used to get into with my brothers and cousins.  They were so much fun.  My father used to own and run a fireworks stand, so growing up I always had crates and crates of left-over fireworks to shoot off – a practically limitless supply.  We would build sophisticated bottle rocket launchers, dress up in camouflage outfits, and fight one another like army soldiers down in the creek.  It felt far more real than firing at each other with sticks or toy guns.

As the memories flashed, I remembered an old weapon I’d created as a teenager.  We all dubbed it “the awesome possum”.  It was the pride of our group, the culmination of years of research and hands-on experience.  Consisting of a thick PVC pipe sealed off at one end, along with a big hole drilled in the side, you’d cram it full of bottle rockets then jam a sparkler into the hole, simultaneously lighting all the bottle rockets at once.  Within about ten seconds, a barrage of hundreds of rockets would come screaming out of the pipe, exploding in every direction.  It was the ultimate firework weapon.

We dubbed it “the possum” because just when you thought it was dead, unfired rockets would spontaneously light themselves, leading to a second wind.  Armed with “the possum”, enemy combatants were scared to rush you.

I called up my buddy Greg and said, “It’s time to resurrect the possum.”  Enthralled with the idea, he decided to join me and we went to Lowe’s and bought fresh PVC pipe, mesh shielding, and duct tape.  I was ready to relive my childhood glory days.

We epically filmed every step of the assembly process and were planning to edit it all into an construction montage with the Rambo 2 preparations theme in the background.

First we scavenged the garage for tools.  We grabbed a drill, wire snips for the mesh, and then a box of drill bits.  On we went, drilling the hole in the pipe, next attaching a huge handle, and attaching the wire mesh to the back for air ventilation.  Finally we added epic black stripe decorations using electrical tape.

It was magnificent.  An epic masterpiece.  This was far bigger and better than anything I had access to as a child.  All that was left was the fireworks themselves.  We went by a firework tent in town and bought whistler rockets and morning glory sparklers.  I could barely contain myself.  When we arrived back at his place, I tore into a box of whistler rockets, crammed seven or eight dozen rockets inside, and got out a morning glory sparkler.  This was it.

I told Greg to get the camera rolling. Wearing a full Rambo’esque commando outfit, I was going to strike a pose like Slash in the Guns and Roses November Rain guitar solo scene.  With the possum arc’d into the sky, I planned to close my eyes in triumph as a screaming barrage of rockets flew into the golden sunset, accompanied by hundreds of rocket explosions, one after another.


I pulled out the lighter and lit the first sparkler.  Sparks and flames started spitting and sputtering from the little green and blue stick.  Yeah baby, this was it!  I crammed it into the hole and the rockets began to ignite and a few blazed into the sky!  With my eyes closed, I stood there, waiting and waiting, but nothing else was happening.  Something was wrong, very wrong.

First off, the sparkler had went out on me.  What the heck was this?  Was it not getting enough oxygen?  And the whistler rockets were total wussy wimps.  They could barely fly six feet out of the cannon before petering out with a mild plop on the ground.  They couldn’t even hold themselves up in the sky.  Their explosions were puny thuds in the nearby grass.

I waved to Greg “Cut, cut!”  A total disgrace.  What happened to my moment of glory?  There’s no way I’d ever let anyone see that footage.  It was simply embarrassing.  I’m a prideful man.

Frustrated but still hopeful, I relit the sparkler.  Ok, take two.  I arc’d my back again and struck my pose.  Here it was!  I channeled my inner Slash and let November Rain play in my head as the camera rolled.  As the guitar solo went forth in my mind, I slowly lowered the sparkler toward the hole, but the unthinkable happened; the sparkler went out before I could even get it in the hole.  Oh my gosh, you’ve GOT to be kidding me!  This can’t be happening!

I threw the stupid sparkler on the ground and angrily screamed out, “Get me another sparkler.” I was practically a spoiled diva.  We got another sparkler and set up for another take.  I lit it, got into my pose, and all that, yada yada.  And guess what?  The piece of garbage sparkler petered out within a few seconds, just like the last one.  I mean c’mon, seriously, all I’m asking for is a child’s sparkler.  Can’t I have that much?  I’m trying to celebrate the birth of America, and here I am dealing with p.o.s. fireworks.

It turns out all the fireworks I’d purchased had been exposed to too much moisture.  Hooray for small town firework tents.  Either that, or fireworks these days have been made politically correct — watered down, dog and pet friendly, and completely sissified.  I mean seriously.  Then I heard Greg say the unthinkable, “Maybe your childhood memories are a bit … exaggerated.”  I was filled with inner rage.  “Nonsense!  The possum was the most epic thing I’ve ever built.  It won’t end like this.  You’ll see!  YOU ALL WILL SEE!”


It was getting late and all the firework tents and stands were closed, so we had to call it a night, but I assure all of you, this isn’t the end.  The possum will rise again, rockets blazing into the sky like a fiery phoenix.  You all mark my words!  And when I complete my mission — and I will — I’m going to upload it here on this site for all you to see!


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Adults Should Think About Time and Space

While studying general relativity today, I came across this wonderful quote from Albert Einstein.

“I sometimes ask myself how it came about that I was the one to develop the theory of relativity.  The reason, I think, is that a normal adult never stops to think about problems of space and time.  These are things which he [or she] has thought about as a child.  But my intellectual development was retarded, as a result of which I began to wonder about space and time only when I had already grown up.”

– Albert Einstein

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How I’m Spending The Summer

For most of this summer, I’ve been studying general relativity.  I have a pile of physics textbooks here on my desk and I’ve been reading and working through them.  When I research something, I tend to go online and find book reviews and order the textbooks which get the highest reviews.  Strangely, that process didn’t work so well for me with general relativity.

If you read the reviews, they’ll all tell you go with Bernard Schutz’s A First Course in General Relativity.  So I did, and I worked through a bunch of it, but I really don’t care for it.  I did not find it very clear.  I ended up reading several other textbooks, but the one which really worked for me is this one.


It’s extremely clear and easy to understand.  It’s filled with all kinds of helpful pictures, has lots of worked examples, and concepts are explained very clearly.  I can’t recommend it more.

I found this textbook by chance when I was looking for solutions to another textbook I had already purchased.  There are university course websites where professors use a particular textbook and have assigned homework problems to their students and then post their solutions.  That’s really helpful to a person who self-studies like me.  A professor had posted solutions to about half of the problems in this book and I was really excited about that.  Plus the course had all kinds of special notes the professor wrote up, explaining things even more. That’s just perfect for me.  Past exams with solutions.  Past homework with solutions.  I can work through an entire course on my own that way.

Another great book to learn the main concepts and ideas from is Exploring Black Holes: Introduction to General Relativity, by Edwin Taylor and John Wheeler.  This book avoids tensors entirely, explaining all the concepts using basic high school level calculus.  You’d think that would limit the authors to explanations that are too basic to be worthwhile, but you’d be wrong.  I’ve learned a great deal from it.


Using words and thought experiments, Wheeler manages to explain the central ideas without resorting to all this complicated tensor mathematics.  It’s fantastic.  It’s helped me have a much deeper intuitive understanding of what goes on within black holes, curved space-time, and all that sort of thing.

As for all the general relativity textbooks, most all of them offer brief introductions to tensor mathematics, but it’s not thorough.  They all begin with a short crash course on contravariant and covariant vectors, tensors, manifolds, metrics, and all that.  But if you want to learn the mathematics of tensor calculus really well and “get” it, I’d highly recommend Pavel Grinfeld’s textbook Introduction To Tensor Analysis and the Calculus of Moving Surfaces.


I would rate this textbook a 10 out of 10, and I think most mathematics books are god awful.  It’s incredibly clear.  With most math books, I find myself reading and re-reading, and re-reading the definitions and concepts, and slog through the “proofs” which never make any sense.  This book isn’t like that at all.  I just sat down and read it and it all made sense to me from the get-go.  And then I went to work the problems and since everything was explained so well, I pretty much immediately knew how to work the problems.  If you search online you can find a complete solutions manual.

For fun I’ve been reading the Feynman Lectures on Computation.  This is a collection of lectures Richard Feynman gave toward the end of his life on computers and digital electronics.  It covers things like what’s computable and what isn’t, Turing machines, Shannon’s Theorem, reversible computation, the thermodynamics of computation, quantum limits of computation, and the internal structure of digital devices and their limitations.  Very cool book.


I’ve also been doing a lot of running — roughly 8 miles each day.  I may well be in the best shape of my life!

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Man Walks Into Airport With Assault Rifle

There is so much fear in the world.  Fear itself isn’t a bad thing, as there are legitimate dangers in the world, but we live in too much fear.  The problem with humans is we have a limited perspective, giving us limited knowledge.  When you combine this with a powerful imagination, there’s no end to the number of imaginary threats we can conjure up.

Just the other day, a man from Georgia waltzes into an airport with a fully loaded AR-15 assault rifle hanging from his neck.  You’d think this is going to be yet another mass shooting, but it wasn’t.  He was just some guy dropping off his daughter.

Apparently the state of Georgia allows a person to acquire an open-carry permit, allowing this man to take his assault rifle with him everywhere he goes.

When airport security was cautious and approached him, asking him why he was carrying that assault rifle around, he became indignant.  He told the police officers, over and over, that it’s his right to carry it with him everywhere he goes.  To the bank, the grocery store, the barber shop, literally wherever he goes.

What sort of threats does this guy imagine?  What sort of wild conspiracy theories are running through this man’s head?  Does he think Al Qaeda terrorists are waiting to blow themselves up while he’s getting his prescription medications at Walgreens?  Does he plan on sitting in the high school parking lot, waiting to stop the next lone school shooter?  Is he going to personally patrol the borders and keep out the illegal immigrants?  If an inner city drug addict robs a convenience store, does he plan to jump out of his car and unload on the poor guy for stealing $250?  I don’t understand what he hopes to accomplish with an AR-15 assault rifle with a giant magazine of ammunition.

I’m very uncomfortable with untrained people carrying loaded weapons which could easily kill a crowd of people in less than a minute.  We have war veterans suffering from PTSD, loons whose heads are filled with conspiracy theories, and hot heads all carrying powerful weapons around with them.

I’m uncomfortable being the grocery store, knowing the person behind me is packing a gun.  I don’t know this person.  I don’t know what they believe.  I don’t know what sets them off.  I don’t know their history.  It’s very uncomfortable.

The only people I want carrying guns are trained professionals who have been informed as to how to handle criminal situations and have went through proper psychological screening.  If a person wants a handgun at home for self-defense, and they keep it at home, I suppose I can get behind that.  I don’t want them all over town.

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