Tuesday, June 28, 2011

The Tau Manifesto

Welcome to The Tau Manifesto. This manifesto is dedicated to one of the most important numbers in mathematics, perhaps the most important: the circle constant relating the circumference of a circle to its linear dimension. For millennia, the circle has been considered the most perfect of shapes, and the circle constant captures the geometry of the circle in a single number. Of course, the traditional choice of circle constant is π—but, as mathematician Bob Palais notes in his delightful article “π Is Wrong!”,1 π is wrong. It’s time to set things right.

Monday, June 27, 2011

Morality and the Bible

I've long wanted to make some sort of chart that had rebuttals to the common arguments people had for believing in gods.  I've been too lazy to ever actually do this (besides there are quite a few on the internet already).  However, one of my favorite arguments is morality.  As in, the Bible gives a moral code and without it one cannot be moral.

This is fun because the Bible describes and condones a number of things that can only be called atrocious.  This leaves two choices:
A. You agree with all the horrible things in the Bible.  In which case, you are a sociopath.
B. You recognize that some parts of the Bible are morally wrong, and should be ignored.  In this case, you've used your own moral judgement, proving that you don't need a moral code written by someone else.

Anyway, if you'd like to read some of the crazy things the Bible says this is a good site:

RSA Animate - Drive: The surprising truth about what motivates us


Where You Shouldn't Live

There was a discussion on Slashdot about if risk of natural disasters could be avoided by choosing to live somewhere safer.  I found a few interesting lists of disasters in the US, and figured I'd share them here.

In particular, that first link has a lot of interesting maps and charts, including the pretty picture I've included here.  If you read through them it should be pretty clear that there are certain areas that are at much higher risk for natural disasters than others.

As with any data, you have to be careful about what it really tells you though.  I wish they would use counties instead of states for one.  Also, instead of total number of events, I'd prefer total number of deaths or damages.  I'm also unsure if these should be adjusted for population or for area.  Even so, any state with more disasters than either the largest (Alaska) or most populated (California) state is probably a poor choice.

Sunday, June 26, 2011

Rochester Police Hand Out Curb Violation Tickets to Emily Good Supporters

The video below is from a Rochester, New York, neighborhood meeting in support of Emily Good, the woman arrested for videotaping a traffic stop from her front yard. So Rochester police sent four squad cars to ticket the cars of meeting attendees who parked more than 12 inches from the curb. Yes, they even brought a ruler.
On May 12th, A Rochester woman was arrested for taping a traffic stop in front of her 19th Ward Home. She was standing in front of her house with a hand held recording device when the arrest happened. Officer Mario Masic, Rochester Police Department, executed the illegal arrest.

The Basics of Regex

A while ago it was suggested I write something about regex (regular expressions).  At the time I didn't want to because (A) I don't feel very qualified to write about them, and (B) there is already a lot of stuff about them.  Well, I have been using regex more and more lately, and while neither A or B have changed, what's the point of a blog if it's not filled with redundant inaccurate information?

Regex is an extremely useful tool for anyone that uses a computer.  For one thing, it is the only good way to write a program to parse some text.  However, many other programs use regex for searching.  Thus, even if you don't program it is still worth learning regex.  As an example, Notepad++ allows regex for its find and replace feature, which is hugely useful.  While regex has a reputation for being extremely complicated, the basics are rather easy.

Before I begin I have to recommend this page.  This is where I go every time I'm writing anything more than a simple regex.  In addition to that reference, this is a great regex tester.  Also I'll be basing this on Perl regex, which is what I'm familiar with.  It should be pretty similar to other languages, particularly at the basic level I'll be going over.

Let's begin with a basic example:
if($string =~ m/test/) {print "True"}
In this example $string is our test string; we are testing to see if something is in $string. 'test' is what we are matching for; if $string contains the substring 'test' then the if statement is true. The =~ and m are Perl specific. The m stands for match, which means Perl will return true if it finds the search string. It could also be s for substitute (find and replace) or tr for translate. The forward slash / is what Perl typically uses to separate the parts of the regex. As an example if we wanted to replace 'test' with 'TEST' we would use:
$string =~ s/test/TEST/
Note the only changes are the m becoming an s (substitute), and the second half of the regex added, again using forward slashes to deliminate. To simplify and make this more general, from here on out I'll just show the actual regex, like this:

Now to begin going over what the characters inside a regex do. To begin, alphanumeric characters (a-z, A-Z, and 0-9) represent themselves. That is why in the above example replacing 'test' with 'TEST' didn't require any special characters. If you wish to match a non alphanumeric character, the safe practice is to escape it. This means you put a backslash \ before it. The backslash says that the character that follows has a special meaning. In the case of non alphanumerics this special meaning is just the actual character matched literally. In the case of alphanumeric it will match a variety of different things I'll get into shortly. As an example this will match on a single period:
If you wished to match a double quote followed by a period you would do this:

Now I'll go over what meaning the non escaped non alphanumerics and escaped alphanumerics have:
^ - this typically matches only at the start of the string.
That will match on the string 'The day is over', but will not match on 'Is the day over?'. In the second case the fact that 'the' is not at the start is why it didn't match. Confusingly, ^ also serves to negate a character class, which we will go over later.

$ - this is the opposite of ^ in that it matches only at the end of the string.
This will match on 'Good bye', but will not match 'Good bye.'. The key difference being that the second ends with a period, which isn't included in the regex.

These can be combined:
This will only match exactly 'bye', it will not match on 'bye.' or 'good bye'.

Next come wildcards, ie, things that will match any of a certain type of character. Note they only match a single character. If you want to match more than one there are other characters we will discuss.

. = Matches any character, the tradition wildcard.
\n = a newline, or what you get when you press enter.
\t = a tab.
\s = Matches white space, which include normal spaces, tabs, and newlines.
\S = Matches non white space. A trend is the capitalized version of a wildcard matches anything that wouldn't be matched by the lower case version.
\d = Matches digits (0-9).
\D = Matches non digits.
\w = Matches "word" characters, alphanumeric and underscore _.
\W = Matches non word characters.
\x2a = Matches the ASCII character represented by that hex value. The \x represents hex, the following two characters is the hex value. In this case 2a is 42 in decimal, or an asterisk *. See here for an ASCII chart of hex values. Using this you can easily represent any character you wish. Note that you can usually get away with not using this, which will be more readable. But this has the advantage of letting you be certain the characters will be matched as you intended.

This will match any character followed by two digits, then a hyphen, then two more digits, then another hyphen, and two more digits. As in '11-06-18', likely a date. Note it will only match two digits. However, '2011-06-18' would also match simply because it wouldn't care about the 20 at the start. On the other hand, '06-2011-18' would not match.

As noted above, the wildcards are treated as single characters. If you wish to match more than one character (either wildcards or actual characters) then you must follow them with one of the following:
* = match 0 or more times (as in match even if it's not there).
+ = match 1 or more times (it must be there, but can be repeated any number of times)
? = match 0 or 1 times exactly.
{n} = match exactly n times.
{l,m} = match between l and m times. If you wish to just use the lower bound you can leave the other out. {4,} will match 4 or more.

I should give some more details about ?. By itself matching 0 or 1 times isn't that useful. But when you follow any of these with a question mark it will make the expression "non greedy". By default regex will match the largest substring it can, this is "greedy". If I wanted to match anything that started and ended with a space I could use:
This will match a space, followed by one or more characters, followed by a space. The problem with this is that it would match from the very first space it found, until the very last. In other words, given a paragraph to match from, it would match almost the entire thing. To make it match on individual words you could force it to be non greedy:
Now it will match the smallest string possible, as in a single word.

Another feature of regex is flags that follow the regex. In Perl the format is:
Here g is the flag. There are a few common flags:
i = Match case insensitive
g = Match global. This is useful for substitutions. Ordinarily, Perl would stop after the first substitution, g tells it to substitute as many times as it can.
m = Treat as multiple lines. This affects how ^ and $ work. Normally ^ would fail to match if it followed a newline. With the m flag each line gets treated as if it were a separate string.
s = Treat as single line. This affects how . matches. Normally it doesn't match on newline itself. This flag will cause it to match newlines as well. The flags s and m can be used at the same time. It will cause . to match newlines while also causing $ and ^ to treat newlines as beginnings and endings.

Now we can start writing some decently powerful regex.
This will match an IP address. Which follow the pattern of 4 groups of between 1-3 digits separated by periods. It will match on '', for example. Note that in valid IP addresses each number can't be greater than 255, which this regex won't care about.

Regex has two more interesting features (well it has a lot more than two, but two more that I'll be going over), classes and groups. Classes use [] while groups use (). Groups give a way of matching any of several different choices. (a|A) will match either lower case a or upper case A. The pipe | is used as a deliminator. They can be full words or anything as complex as you'd like. (apple|peach|banana) will match either of those three fruits. (\d{2}|\d{4}) will match either 2 or 4 digits, but not 3. In addition to matching any of a choice, groups provide a way to access the string that matched later on. Since this is more complex and somewhat Perl specific (although very useful) I won't explain it. See this site for an example.

Classes allow you to match anything from a range. This allows you to create your own wildcards. Probably the most common usage (at least for me) is [a-zA-Z], this will match any letters, but not digits. Note the lack of a space between z and A, if you include a space then it will also match on spaces.

If you remember way up above I mentioned ^ would also negate a character class. This is where that comes back. For both classes and groups putting a ^ at the start will cause it to match on anything that would not match on otherwise. In other words [^a-zA-Z] will match on everything except letters.

As an example of this how would we match all three letter words?
This might be a first thought, but it has the flaw of only matching letters that are surrounded by spaces. Words can also be immediately followed by a period if they end a sentence (as well as a wide variety of other things). Instead of looking for letters surrounded by spaces we should instead look for letters surrounded by any non letter.
This is better, but still has some flaws. It will match on 'www.google.com'. The 'www' and 'com' parts will each match. One solution would be to require a space at some point (after any number of non letters). Combining the two previous examples we get:
This reads as, match a space, followed by any number of non letters (0 or more), followed by exactly 3 letters, followed by any number of non letters, followed by a space.

Thursday, June 23, 2011

Think Like a Physicist


Multicellular life arises in a test tube

Common lab yeast normally live as single cells that bud off single-celled offspring. But challenging generations of yeast with conditions that make solo life tough led to spiky multicelled yeast forms within about two months, said Will Ratcliff of the University of Minnesota, Twin Cities. The experiment suggests going multicellular may happen more readily than previously thought, he told the Evolution 2011 conference June 18.
This is far from the first experimental evidence for evolution.

Sunday, June 19, 2011

War Powers Act

There has been some discussion lately about the War Powers Act, and what exactly the President is allowed to do without approval from Congress.  As a constitutional law scholar* I thought I'd summarize the situation.
*Note: By "constitutional law scholar" I mean "guy with access to Wikipedia".

Article 1 Section 8 of the Constitution lists all the things Congress has the power to (legally) do.  It includes the following:
"The Congress shall have Power...
To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water;"

Article 2 Section 2 of the Constitution declares the President the commander in chief of the military:
"The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States;"

A logical reading of these two clauses would suggest that Congress has the power to decide to go to war, and once that decision is made the President would provide the ultimate authority for how the military conducts that war.  It is no secret that we have not declared war since 1941; all wars after WWII were fought without declarations of war.  The Constitution doesn't specifically require a declaration of war, even though it's clear it intended for there to be a declaration of war before a war was fought.  Instead of declarations of war, Congress has given authorizations for war. Since there is no special requirements needed to pass a declaration of war vs an authorization (ie they are both normal laws), in practice this has little weight. While I'd like to see a return to formal declarations of war, it is pretty much a semantic change which reflects the general softening of terms with time.

The current law that deals with war is the War Powers Act of 1973. This law basically says that the President may use the military without congressional approval for between 60-90 days when needed. The law is actually pretty short and easy to read, so I recommend reading it yourself:

Here is some of it:
In the absence of a declaration of war, in any case in which United States Armed Forces are introduced—
(1) into hostilities or into situations where imminent involvement in hostilities is clearly indicated by the circumstances;
(2) into the territory, airspace or waters of a foreign nation, while equipped for combat, except for deployments which relate solely to supply, replacement, repair, or training of such forces; or
(3) in numbers which substantially enlarge United States Armed Forces equipped for combat already located in a foreign nation;
the President shall submit within 48 hours to the Speaker of the House of Representatives and to the President pro tempore of the Senate a report, in writing
Within sixty calendar days after a report is submitted or is required to be submitted pursuant to section 1543 (a)(1) of this title, whichever is earlier, the President shall terminate any use of United States Armed Forces with respect to which such report was submitted (or required to be submitted), unless the Congress
(1) has declared war or has enacted a specific authorization for such use of United States Armed Forces,
(2) has extended by law such sixty-day period, or
(3) is physically unable to meet as a result of an armed attack upon the United States.
Such sixty-day period shall be extended for not more than an additional thirty days if the President determines and certifies to the Congress in writing that unavoidable military necessity respecting the safety of United States Armed Forces requires the continued use of such armed forces in the course of bringing about a prompt removal of such forces.
The law goes on to state that no law or treaty may authorize war unless it explicitly says so. It also says that the President has no authority to fight wars outside of those granted in this law.

So that is the background info. The current situation is that the US has deployed to Libya with only the president's approval. The conflict began on March 19th, and the required report was submitted to Congress on March 21st. 60 days after the report was May 20th, 90 days was June 19th. Since the deadline was coming up and Congress wasn't going to approve the war, the White House had to come up with different justification. On June 15th the White House released a 32 page report that said the War Powers Act didn't apply.
White House: US 'can act in Libya without Congress'

While the report is 32 pages, the part that deals with the White House's justification for ignoring the War Powers Act is only a paragraph:
Given the important U.S. interests served by U.S. military operations in Libya and the limited nature, scope and duration of the anticipated actions, the President had constitutional authority, as Commander in Chief and Chief Executive and pursuant to his foreign affairs powers, to direct such limited military operations abroad. The President is of the view that the current U.S. military operations in Libya are consistent with the War Powers Resolution and do not under that law require further congressional authorization, because U.S. military operations are distinct from the kind of "hostilities" contemplated by the Resolution’s 60 day termination provision. U.S. forces are playing a constrained and supporting role in a multinational coalition, whose operations are both legitimated by and limited to the terms of a United Nations Security Council Resolution that authorizes the use of force solely to protect civilians and civilian populated areas under attack or threat of attack and to enforce a no-fly zone and an arms embargo. U.S. operations do not involve sustained fighting or active exchanges of fire with hostile forces, nor do they involve the presence of U.S. ground troops, U.S. casualties or a serious threat thereof, or any significant chance of escalation into a conflict characterized by those factors.
At this point it is a good idea to reread the first quoted section of the War Powers Act above, and attempt reconcile it with the White House's claim. An important issue is if drones count as US Forces. I'd probably have to say no to that. In that case clauses (2) and (3) don't apply. Unless US fighters are flying in Libya airspace. In that case (2) seems to apply pretty plainly. Only one clause needs to apply in order for the law to apply (note the use of or between clauses). So let's look at (1) again:
"in any case in which United States Armed Forces are introduced into hostilities or into situations where imminent involvement in hostilities is clearly indicated by the circumstances;"

So it comes down to if remotely fighting a war counts as being introduced into hostilities. If it said engaged instead of introduced I'd have to say yes. As it stands, introduced does sound to me as if it could only apply to situations where there is a threat to US Forces.

That's a technical reading of the situation. The reality is that it's clear that this action goes against the spirit, if not the letter, of the law. In addition it is clear that even those in a position to likely agree don't necessarily do.
2 Top Lawyers Lost to Obama in Libya War Policy Debate

The rational answer to this would be for Congress to simply pass another law clarifying what exactly constitutes hostilities. Unfortunately, we live in the real world. In the real world people align themselves with teams, and the people on the same team as the President won't do anything that is perceived as going against him. Those on the opposite team will do anything to interfere with him. The Senate has a majority on his team, and no surprise, support the war. The House has a majority on the opposite team, and you guessed it, are against it. So the reality is that no clarification will be passed. A lawsuit has been filed, but there is a legal concept called the "political question doctrine" which states that courts won't rule on issues it deems political. Prior challenges to wars have been dismissed for this reason. At most, the House may not fund it. However, I don't know how that would work, if there is already funding for the rest of the FY or what.

Sunday, June 12, 2011

An Intro To Star Trek

I decided there could be people reading this blog who are unsure of what level nerdiness I have.  The answer to this problem will be this post giving basic info and the various Star Trek series possibly followed one day by one on races.  I've listed the five television series in chronological order by original airing.

Star Trek: The Original Series

Aired: 1966-1969
Time Period: 2265-2269
79 episodes / 3 seasons
Significant Races: Federation, Klingons, Romulans

Star Trek: The Original Series (TOS) is the classic series from the 60s that started Star Trek.  It has a rather different feel than any of the modern Star Treks (which start in the late 80s).  There is a lot more romance than the newer series and the action is cheesy at times.  Having grown up with the modern Star Treks I prefer them.  However, I will admit that the movies from the TOS era are better than the newer movies.

In TOS the starship Enterprise travels around exploring worlds and solving problems that invariably arise at these alien worlds.  A typical episode will involve the Enterprise discovering some unusual phenomenon and then investigating.  This leads to some dramatic problem, either a technical problem that threatens the ship, or a philosophical problem with the culture.  The characters use their resourcefulness to solve these problems and at the end of the show everything is as it began.  The episodes are very much self contained and there isn't much lost by watching them in random order.

Star Trek: The Next Generation

Aired: 1987-1994
Time Period: 2364-2370
176 episodes / 7 seasons
Races: Federation, Klingons, Romulans, Ferengi, Borg

Star Trek: The Next Generation (TNG) is set roughly 100 years after TOS.  There are stylistic differences due to the change in time (both in universe and real world), but is otherwise a similar show to TOS.  The Enterprise-D explores, finds something strange, which leads to drama, which is resolved.  I don't want my short write up to be interpreted as a sign this isn't a good series.  Indeed, TNG is considered the best series by many.  There just isn't much more to say other than it is an updated version of the original.  If one wishes to get a general sense for Star Trek it is probably a good intro show.

Star Trek: Deep Space Nine

Aired: 1993-1999
Time Period: 2369-2375
176 episodes / 7 seasons
Races: Federation, Klingons, Romulans, Bajorans, Cardassians, Ferengi, Dominion

Star Trek: Deep Space Nine (DS9) is an interesting series.  When TOS was created one of the guiding rules is that there are no internal problems in society (at least in the Federation, the analog of the USA that the human race is a part of).  No racism, sexism, money, poverty, sickness, etc.  All the problems come externally.  DS9 changes this and explores a darker side.  I don't want to give the impression that it is completely different than the rest of the Star Trek universe, but there is a clear darker spin on it.  Since DS9 ran concurrently with TNG for a couple years it couldn't use the same formula that TNG and TOS use.  Instead of a ship that travels around the galaxy, DS9 has a space station that the galaxy travels to.

It's necessary here to explain the layout of the Star Trek universe.  In Star Trek the galaxy is divided into four quadrants, with Earth centered along the dividing line between the bottom two quadrants (6 o'clock).  Starting with the bottom left and working counter clock wise they are named Alpha, Beta, Delta, Gamma.  The normal star trek universe takes place in a rather small portion of the alpha and beta quadrants, however for whatever reason, they really only ever mention the alpha quadrant.  It would take a ship about 100 years to cross the galaxy (about 100,000 light years).  All this means that at the start of DS9 the delta and gamma quadrants are unexplored.

DS9 sets out to explore the gamma quadrant via a newly discovered wormhole.  This wormhole allows instantaneous travel from the alpha quadrant to a point deep within the gamma quadrant.  It is discovered that the gamma quadrant is largely controlled by the Dominion.  An entity created by the "Founders" who either genetically engineered or conquered all the other member races.  The Dominion attempts to conquer the alpha quadrant, which leads to a large scale war.

Because DS9 is stationary the show flows from one episode to the next much more so than other Star Treks.  Besides the regular cast there is a large group of reoccurring characters that show up regularly.  Combined with the long build up to the war, followed by the war itself, this means this show is much better to watch in order.  There is a six and then a ten episode arc later on in the series.  This doesn't mean there aren't a lot of self contained episodes still.  But even those episodes build on past episodes more so than in other Star Treks.

Because of the changes in the style and semi-serialized nature of DS9 it tends to be very polarizing.  There seems to be about equal amounts of people that are sure it is either the worst or best Star Trek series.  I am on the best side of that debate.  In particular, I like the social commentary on terrorism and what is acceptable to give up to win a war.  This is made particularly profound by the fact that the series ended in 1999, before our current wars.

Star Trek: Voyager

Aired: 1995-2001
Time Period: 2371-2378
168 episodes / 7 seasons
Races: Federation, Borg, Kazons, Hirogens

Star Trek: Voyager (VOY) began right as TNG ended, and thus continued the traditional theme of a ship exploring the galaxy from week to week.  However, it dealt with the other unexplored quadrant mentioned above, the delta quadrant.  It does this by having the ship be pulled into this unexplored space in the first episode by a powerful alien.  The ship is then about 70 years away from home and spends the rest of the series attempting to get home.

Since the show is set entirely in this new quadrant there is much less of the traditional races.  In addition, since the ship is moving through the quadrant there are phases when they are near one particular race's territory.  Still the format is fairly similar to TNG/TOS.

The general consensus seems to be that Star Trek series have gotten worst with time.  As such, there are many people that feel VOY is the worst.  Its main flaws are a large amount of technobabble and deus ex machina endings.  Personally, I've never been bothered by those things, and find VOY to be pretty good.

Star Trek: Enterprise

Aired: 2001-2005
Time Period: 2151-2155
97 episodes / 4 seasons
Races: Federation, Vulcans, Klingons, Andorian, Xindi

Star Trek: Enterprise (ENT) serves as a prequel to TOS.  It is set about 100 years prior to TOS.  In this time Earth is just beginning to explore the galaxy, and many things that are common in later years are either missing or discovered during this show.

The format is similar to TNG/TOS, explore a new world every week.  However, it does seem to try to follow DS9 with serialization.  There are a few very long arcs lasting entire seasons.  As I said above, many people feel Star Trek series have only gotten worse with time, and this show is no exception.  When it originally aired I stopped watching half way through its run.

That being said, years later I rewatched it and liked it better.  The first two seasons aren't strong, and have a big time travel arc, which is never that good, but all the Star Treks have had weak beginnings.  The last two seasons get to be pretty good.  it is a shame it was cancelled there, as the show was getting good.  In addition, the show barely touched on two major events that occur around that time (Romulan War, and foundation of Federation).  Had it not been cancelled those would have made great arcs for the following seasons.

Sunday, June 5, 2011

Man Ordered At Gunpoint To Hand Over Phone For Recording Cops

"Miami Beach police did their best to destroy a citizen video that shows them shooting a man to death in a hail of bullets on Memorial Day. First, police pointed their guns at the man who shot the video, according to a Miami Herald interview with the videographer. Then they ordered the man and his girlfriend out of the car and threw them down to the ground, yelling, 'you want to be f****** paparazzi?' Then they snatched the cell phone from his hand and slammed it to the ground before stomping on it. Then they placed the smashed phone in the videographer's back pocket as he was laying down on the ground."

Friday, June 3, 2011

Update on Ashcroft v. al-Kidd

The Bush Administration’s wide use of an arrest tool to take terrorism suspects off the streets barely — and perhaps only temporarily — survived a major test in the Supreme Court on Tuesday, even though its principal architect — former Attorney General John D. Ashcroft — will not have to go to trial to defend it.  While finding that Ashcroft is entitled to limited legal immunity for a single, controversial use of the tactic, fully half of the eight Justices voting on the case sent out clear indications that they are deeply skeptical about it.  That was the somewhat contradictory outcome in Ashcroft v. al-Kidd (docket 10-98).

How to Tie Five Useful Knots

I do some outdoors activities like backpacking and canoeing.  During these activities, there is occasionally a need to tie knots.  I've noticed that no one in our group (myself included) knows how to tie any knots, and I feel this would be a useful skill.  I did some searching and found a small set of knots that seem to be pretty useful and learned them.  They are all relatively easy to learn, although I must say figuring out knots from pictures can be a bit confusing.  Luckily, this Animated Knots site is pretty good.

Square knot (Reef knot)

A square knot is one of the most basic knots. Prior to learning these knots it was pretty much the only knot I knew. It's easy to tie and looks pretty with its symmetricalness. That being said, it is apparently a pretty poor knot to use. "There have probably been more lives lost as a result of using a square knot as a bend (to tie two ropes together) than from the failure of any other half dozen knots combined." - Some Knot Expert. In addition to its tendency to come undone it is very easy to accidentally tie the much worse granny knot. It's easy to spot a granny knot when tying, so go to the above site and look at the differences.

Sheet Bend

The sheet bend is similar to the square knot, except better.  Since it holds much better than the square knot, and is just as easy to tie, it should be used instead of a square knot whenever possible.  It is also useful for rope of different sizes.

Double Fisherman's Knot

This is a good knot for connecting two pieces of rope into a longer one. I knew this knot before, but the single version. The double is bit more than just tying a double knot, but still pretty easy. Once you know the double you can easily do the triple or more for added security.  I must say the animation was a bit bewildering at first, but you are essentially just looping the rope around itself and the other rope twice and then passing it back through those loops.


The bowline is a pretty good knot, useful for putting a strong loop at the end of a rope. It is probably the most complicated knot in this list, but really isn't very hard at all. The general consensus seems to be that this is the best knot for forming a loop, strong under tension and easy to untie (without tension). Its one flaw seems to be that it can undo itself if there is a lack of tension, which seems like it could be fixed by adding a double overhand knot to the free end (half a double fisherman's knot).

Half Hitch

Frankly, I don't think the half hitch seems that useful. It is used to lash rope to a post, but the bowline seems better to me. I did see it mentioned a lot as a useful knot which is why I'm including it here.  It's also worth noting that a half hitch by itself is pretty weak, but it almost always followed by another half hitch (making a full hitch I guess).

Bonus Knot:
Because I like you so much I'm throwing in an additional knot for free.  I'm pretty sure I've mentioned this knot here before, but I think it deserves an additional mention.  It is a much more secure way of tying your shoes.  I have a pair of old sneakers on which the laces of worn down so smooth that even double knots would come untied in a few hours.  This knot has never come untied on its own (and I leave my shoes tied for months just slipping them on and off).  It is basically the same as the bunny ears method of tying your shoes, but you tuck both ears through the center instead of just one.

Thursday, June 2, 2011

Embed a Video, Go To Jail?

"A few weeks ago, Slashdot had a post about the new bill in Congress to make streaming infringing videos a felony, punishable by up to 5 years in jail if just 10 people watch the video. As more details come out, the bill keeps looking worse and worse, as it appears that the definitions used in the bill would mean that merely embedding or linking to an infringing YouTube video could put you on the hook for jail time. Obviously, supporters of the bill insist that's not who will be targeted with this bill, but just the fact that they could be should be worrisome enough. We've seen other laws "misused" in the past."