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Dan Thompson
Attended University of Texas at Austin
Lives in Austin, TX
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Dan Thompson
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Science Fact  - 
 
Antarctica without its ice...

I'm look at that picture, and while I'm sure the height levels are exaggerated, it looks like an awesome geography for some epic fantasy.  Take it out of the cold and put it a temperate down to tropical latitudes, and I could see some really cool stuff happening along those cliff lines.
 
Antarctica makes a very cool continent to base your RPG adventures on:
The British Antarctic Survey has produced the sharpest image yet of Antarctica’s rugged topography. And as you can clearly see, without its mile-thick layer of ice, the polar continent would be an incredibly mountainous terrain, indeed.
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And once upon a time it was all forest...
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We have a troublesome desktop in our household that will soon be departing.  I know the responsible thing is to take it down to the city's electronics recycling center, but what I really want to do is set it on fire and launch it from a trebuchet!

Any other suggestions for how to dispose of a terminally malfunctioning computer?
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It's quite easy, +Cypher Porter  to figure out if the HDD is the culprit. If it is, then the red indicator on the ATX casing is "ON" most of the time, if not all the time. If everything runs normally but the system hangs up, then it can be a problem with the OS...
In my parts, obtaining a new computer is never NEVER cheaper than fixing it. Maybe it is there... 

Talking about money, even if I could afford a new one, I would reconsider mending it and then donating the money, or a part of it, to those in need instead... That will help at least two people get along... Buying a new computer while throwing the old one away can only serve one party...

It is your decision in the end and I honour your individuality. I was only trying to give some advice out of a long life of experience... that's all...

All the best, +Dan Thompson , take your pick, whatever it is, whichever it is...
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Bathroom Tiles, Expert Level
 
Perfect Squared Squares

It is easy to tile a square area using smaller square tiles that are all the same size as each other, but tiling a square area using smaller square tiles that are all of different sizes is much harder. 

This picture shows one possible way to tile a 1376 by 1376 square using smaller square tiles that are all of different sizes. The numbers in each smaller square denote the length of each of its sides, as opposed to its area. The solution in the picture has another remarkable property: it is not possible to form a rectangle from the union of a subset of the tiles, except in trivial ways. 

A rectangle that is partitioned into smaller squares is known as a squared rectangle. If the rectangle happens to be square, then it is known as a squared square. If all of the smaller squares have different sizes, the squared square is called perfect, and if no proper nontrivial union of the smaller squares forms a rectangle, the squared square is called simple. The configuration in the picture is therefore an example of a simple perfect squared square, or SPSS for short.

The history of perfect squared squares is surprisingly long. It starts in 1902 when H.E. Dudeney published a puzzle called Lady Isabel's Casket. The puzzle involves partitioning a square into different sized smaller squares together with a rectangle. In 1903, Max Dehn proved the key result that a rectangle can be tiled by squares if and only if its length is a rational multiple of its width. This result can be used to show that if a tiling by squares is possible, then the rectangle can be scaled in such a way that all of its side lengths, as well as all the side lengths of its constituent squares, are integers. Since 1903, a large number of examples of squared rectangles have been produced by many mathematicians. The history of the subject is surprisingly rich, and is recounted in detail in the paper http://arxiv.org/abs/1303.0599 by Stuart E. Anderson.

The simple perfect squared square in the picture was discovered in 2013 by James B. Williams using a computer search. It has the distinctive feature that none of the seven largest constituent squares (shaded in purple) appears as a corner piece (shaded in green).

Now I know what you're thinking. What happens if you try to construct a similar type of square tiling on a cylinder? Or a Möbius strip? Or a Klein bottle? Or a projective plane? And what happens if we use triangles instead of squares? Well, you'll be pleased to know that the site http://www.squaring.net treats all these cases in detail. (You should have a look at the site, because it probably contains more detail than you are expecting.) The illustration here comes from that website, which is maintained by Stuart E. Anderson.

On the other hand, if you're wondering why people would want to study this, I don't have a good answer, except that it is challenging and aesthetically appealing.

#mathematics #sciencesunday #spnetwork arXiv:1303.0599
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Great! This proves that it can be done, but practically, I don't know how this could be achieved in real life... Thanks for sharing though... +Richard Green  +Dan Thompson 
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General Discussion  - 
 
Crossed 1000, and We Missed It!

I'd been keeping on eye on this in recent weeks, and lo and behold, this morning we are at 1002 members!  Welcome aboard!
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The thing that makes Sonic such a go-to place for me is their breadth of menu around the clock.  I can pull up at 3 in the afternoon, get a bacon-and-egg breakfast burrito, a foot-long chili dog, and a side of onion rings. 

Alas, they do not carry Rolaids.
 
Sonic is America’s fourth biggest burger chain, a fact that might surprise you if you live outside of the South. Sonic’s are located mostly around Texas, Oklahoma, Tennessee and Mississippi.
We're Number 4!!! Sonic is the 4th largest burger chain in the U.S. by sales, but concentrated in a few regions.
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Never saw a Sonic before I moved from California to Colorado. Now they're my go-to burger place.
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Discussion  - 
 
Another Thursday Write-in at Mozart's?

Do we want to try another write-in at Mozart's on Thursday morning, say 10am - 1pm?  I'm looking at you +Chrishaun Keller-Hanna +Sonya Craig 
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Yep, let's do this thing!
I'm about to die from Chrishaun withdrawal... fading fast...
:)
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This needs a cool force vector animation...

Attention to you all you cool physics folks out there.  This is a new kind of axe, and while the video is cool... it's basically 8 minutes of chopping wood.  And no, that's not a euphemism. 

The key invention here is a trick of putting the center-of-gravity... well, off-center, I suppose, so that when the axe tip first penetrates the wood and slows down, we get a twisting lever-like action which operates in a direction where the wood is not as strong.

But this would be a lot more visually appealing with a nice vector diagram showing the forces and motions involved.  Anyone got the skills to put that together?

#physics #visualization
 
Basic Physics Revolutionizes the Axe

For how many centuries have we made and used axes the same way?  According to Wikipedia, the earliest axes appeared probably 1.5 million years ago.  Now, a Finnish inventor has reinvented the axe and used physics to make it much, much better.

Traditional axes require a direct transfer of momentum into a solid wedge that must overcome sliding friction to accomplish splitting of wood.  Much of the incident kinetic energy is lost due to this friction and the concomittant lateral compression of the wood in the direction of highest strength. The redsign by Finnish inventor Heikki Kärnä works instead like a lever, with a laterally displaced center of gravity and the rotational inertia providing the fulcrum about the rotational axis.  The axe inserts into the wood a short distance, and as friction slows the downward movement of the axe, the remaining momentum instead translates into a twisting motion that fractures the wood. 

In essence, more energy goes into accomplishing the fracture event that splits the wood along it's weak direction.  Less of the energy is lost into both compressing the wood in its strong direction and overcoming friction between the axe surface and the wood,  

Seen here:

http://boingboing.net/2014/04/17/eccentric-axe-uses-physics-to.html

#ScienceEveryDay   #Mechanics   #wood   #fracture   #axe  
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This looks really cool.  I wish it cost a whole lot less though.  I do wonder if the sudden twisting motion would cause arm pain.

Wish I could try it out.
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Science Fact  - 
 
I recall a Law & Order episode back in the 90s where the motive for the murder came down to a dispute over two possible proton decay models.  What really impressed me was not just how far afield they had gone for a new and interesting motive, but that the two models they presented in a crime drama were both viable in terms of conservation of both spin and charge. 

So yeah, enter the standard model and its open questions: intrigue, mystery, and murder.
 
State of Decay

One aspect of quantum particles is that they can decay into lighter particles, releasing energy.  For example, a free neutron will tend to decay into a proton, electron, and anti-neutrino.  Most particles undergo this kind of decay.  Some decay rather quickly, while others tend to take longer to decay.  There are a few particles, however, that don’t decay.  The electron is stable, as is the lightest neutrino.  Then there is the proton, which might be stable, but we’re not entirely sure why.  

The proton is the lightest of the baryons (meaning that it is made of three quarks), while he electron and neutrinos are leptons. According to the standard model, the quarks are governed by the strong nuclear force, while the leptons are governed by the electroweak force (which is a unification of electromagnetism and the weak nuclear force). Because these two forces are separate in the standard model, there is no way for a proton to decay into lighter particles.

There are quark particles, known as mesons, which are lighter than the proton, but these consist of a quark-antiquark pair rather than three quarks.  In order for a proton to decay into a meson and other particles, there would need to be a way for one of the quarks to decay into a lepton, which isn’t possible under the standard model.  So in the standard model, protons are stable.

The standard model is the scientific theory of particle physics, and it works extremely well.  It describes how everything but gravity works, and experiments have repeatedly validated it, most recently with the discovery of the Higgs boson.  But it is often viewed as an incomplete theory because it doesn’t provide a unified structure connecting the electroweak and strong forces.  For that you would need a grand unified theory or GUT.

We don’t know if such a GUT exists.  It’s possible that there is no unified physical theory, but it’s generally thought that the electroweak and strong forces do unify to form a GUT, and could even combine with gravity to form a theory of everything.  If the electroweak and strong are connected, then it should be possible for protons to decay through some heavy intermediary particle.  Thus if a grand unified theory exists, protons shouldn’t be stable.

The most basic GUT model predicts that a proton can decay into a pi-meson and positron.  The pi-meson would then quickly decay into a pair of gamma rays.  The estimated half-life of the proton is about a billion trillion trillion years, which is vastly longer than the age of the universe.  You might argue, then, that the proton is effectively stable, and you’d have a point.  But that doesn’t mean that we would never see a proton decay.  One of the important aspects of radioactive decay is that it is statistically random, where the half life is the time for which a particle has a 50/50 chance of decaying.  Some particles will decay much more quickly, while others will take much longer.

There have been experiments testing for proton decay, such as the Super Kameokande neutrino detector in Japan.  This detector contains 50,000 tons of purified water being observed by extremely sensitive photodetectors.  It’s main experiment is to observe the effects of neutrinos colliding with atomic nuclei, but given its scale and the estimated half-life of protons it should see about 7 proton decays a year.  So far it has observed none.

As far as we can tell experimentally, the proton is completely stable, and there is no evidence of proton decay.  We just aren’t sure why that is.

Image: The periodic table of fundamental particles.
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I have no comment...
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Apparently a disability specific to applying disability signage stencils. :p
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Science Fact  - 
 
And they just keep coming...
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Anyone who thought otherwise was simply in denial. It's only a matter of time until we can detect signs of life on other worlds. Watch the heads explode...
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In his circles
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Hillary Beemer's profile photo
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Occupation
I write fiction. I used to program for a living, and I probably still could, but for now I write fiction.
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Austin, TX
Story
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Writer, programmer, artist, dude
Introduction
Father of three, programmer, writer, etc.  I do weird stuff with my brain for fun and profit. :)

You can see my blog here: DanThompsonWrites.com

And my books: DanThompsonWrites.com/Books

For my programming, I did 18 years working on Computer Aided Design programs, everything from add-ons to being on the core graphics team for AutoCAD.  These days I'm still doing a little consulting and some personal explorations with genetic algorithms.

I've been writing off and on since I was eleven, but I've been doing a lot more of it in the last 5 years.

I also have special needs kids, and I've spent a lot of my time on them for the last few years.
Bragging rights
Had a startup, sold it, written a few books, survived twins (so far), have done more strange things than most, but nearly as many as I'd like to.
Education
  • University of Texas at Austin
    Computer Science
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Male