Opinion

I think I was around 12 when I read about the famous thought experiment by Galileo that disproved the old notion of Aristotle that heavier bodies fall faster than lighter ones.

Suppose we have two stones, the first being lighter than the second. Release the two stones from a height to fall to Earth. Stone 2, being heavier than stone 1, falls more rapidly. If they are joined together, argues Galileo, then the combined object should fall at a speed somewhere between that of the light stone and that of the heavy stone since the light stone by falling more slowly will retard the speed of the heavier. But if we think of the two stones tied together as a single object, then Aristotle says it falls more rapidly than the heavy stone. How do the stones know if they are one object or two?

(Source)

I remember being stunned by the simplicity and elegance of the argument. No tower of Pisa needed, no pendulum, no inclined plane, nothing! Just a clever way of arranging thoughts.

In any case, I was telling my dad about this argument a couple of weeks ago. He asked me why then do pieces of paper fall to ground more slowly than rocks. It took me a few minutes to come up with a satisfactory answer.

Two questions then for you dear readers.

1. Where exactly does Galileo’s reasoning break down in the presence of air resistance?

2. What are your favorite examples of arguments in theoretical CS or math which are too clever for their own good?

Editors’ foreword

The current post, our first of 2012, is different from others we have published on this blog, and we have created a new category for it: Opinion.  In brief, the author, Guillaume Aupy, opposes the controversial US bill SOPA, and encourages readers to boycott Elsevier for its support of the passage of SOPA.

Rather than state an additional opinion about this topic — which would be out of place in an editor’s foreword anyway — we would like to note that, for better or for worse, internet censorship in an attempt to control copyright infringement is gaining traction in many countries, not just the USA. Most dramatically, just a few days ago, a court in Finland ordered a major internet service provider there to block access to The Pirate Bay — and the web page of the organization that brought the lawsuit fell under a Distributed Denial of Service attack from Anonymous Finland, which has threatened long term action if the Supreme Court doesn’t reverse the IP block.  Even more recently, a Dutch court ordered a block on The Pirate Bay on 11 Jan 2012.  Spain is scheduled to enact a “SOPA-like” law before March 2012.  However, there are already at least three new mirror sites for The Pirate Bay that are (currently) unaffected by any court order, and, of course, it is possible for Finns to visit the blocked sites using an anonymous browsing tool such as The TOR Network.

Given the international context, the US opposition to SOPA is relatively strong.  The popular web site Reddit plans a twelve-hour blackout to protest SOPA on January 18th, GoDaddy withdrew its support of SOPA after losing tens of thousands of customers from a boycott, and there is even a Boycott SOPA smartphone app that scans an item’s barcode and tells the user whether the company that made the item is on the list of supporters for SOPA.  Aupy’s request in the post below is that theoretical computer scientists engage in a similar action.

Main post: Boycott Elsevier for supporting SOPA

The Stop Online Piracy Act (SOPA) is a bill that would allow the U.S. Department of Justice, as well as copyright holders, to seek court orders against websites accused of enabling or facilitating copyright infringement (Wikipedia). My intention here is not to rewrite in a worst fashion what other people already wrote about SOPA, but if you have never heard of this bill before, I really urge you to go read the Wikipedia article, so you can see by yourself in how many ways this bill is wrong. If it can convince you to read about SOPA (and make up your mind), know that opponents of the bill include Google, Facebook, Twitter, the Wikimedia Foundation (these organizations even “talked” about a blackout as SOPA protest (see here and here)), but also eBay, Mozilla Corporation, and human rights organizations such as Reporters Without Borders, the Electronic Frontier Foundation, the ACLU, and Human Rights Watch.

There are however supporters of the SOPA bill. Amongst the many supporter is Elsevier, which I imagine many of you know as a publisher of a lot of TCS journals. It is time for us, the scientific community to raise our voice. A good way may be to

1. Refusing to serve as peer reviewers to Elsevier journals.
2. Not submitting papers to Elsevier journals.
3. If you are an Editor-in-Chief or in the editorial board, let the right people hear about your opinion.

And if this is not enough an argument to boycott Elsevier,  you may also want to remember the 2009 scandal where Elsevier published fake journals as covert advertisements for pharmaceutical companies.