The Northerm Lights

Here's a beautiful black and white picture of the Northern Lights from Outside magazine.

Robotic hand from Sandia Labs

Here's a robotic hand from Sandia National Labs that can hold a hammer, screw driver, fruit, and assortment of other items. The hand can manipulate the item and even put a battery in a flashlight.

On-line courses: Join the Million

Coursera, the company that provides support and Web hosting for massive open online courses at top universities, announced Thursday that more than 1 million students have registered for its courses. The company now serves as a MOOC platform for 16 universities and lists 116 courses, most of which have not started yet.

I took a course from Coursera in Cryptography and it was quite good. I am taking two now; one in quantum computing and one in finance. The courses do take time to watch the videos, do the homework, and simply keep up. Still, they're free, interesting, and if you have the time, worth the effort.

Do you need math?

Here's a discussion on the practicality of algebra.
Enjoy.

Some real science

The "Slow Mo Guys" wrap a watermelon with rubber bands, about 500 of them, and the pressure forces the melon to explode. Now that's some science you can believe.  The link above has a video of the whole process, worth a few minutes to watch. Enjoy.

It's the end of the world as we know it....

I feel fine....

Yes, the world, or really the universe for that matter, is set to end in 16-billion years, and not the original 22-billion years like scientists thought.

So says two physicists from China who have analyzed dark energy and determined that this stuff that we can't see, but infer because the universe is expanding, will one day cause that self-same universe to tear itself apart. And sure they will be stars that will be ripped apart, and planets destroyed, but if we could have just 6-billion more years, well, then the universe would have collapsed on itself. It's death by separation or death by constriction, either way, it's not good.

Sometimes I wonder if anyone takes these physicists seriously, and I actually checked out their paper (link available at the link above) to see what they're thinking.

For my part, I'll just keep living as I have, without worries, at least about this.  You might want to do the same.

Book Review: An Introduction to Modern Mathematical Computing with Maple

I recently contributed a book review to the Mathematical Association of America for the new book by Jonathan Borwein and Matthew P. Skerritt.  In the past I did not post those reviews here but I thought I should try it out and see how that goes. Here's the review.

In An Introduction to Modern Mathematical Computing with Maple, Borwein and Skerritt show that computers are an excellent companion for learning mathematics. They do so not with an essay on the advantages of computers, say, less sign errors, or quicker algebraic manipulations, both of which are true. Rather, they show readers that a particular computer algebra program, for their case Maple, is so flexible and powerful that it can work alongside students to show them insights that may be otherwise difficult to see.

To that end, the authors go through many aspects of Maple such as: algebraic manipulations, graphics, matrix manipulations, integration, differentiation, sums, limits, and number theory. Their treatment of the program is thorough, well explained, and instructive. This book is a good companion to the user manual and, maybe even better than the manual on some topics because the authors' examples are succinct and clearly illustrate many facets of the program. (It is not a replacement for the user's guide, by the way.)

The theme of the book is that Maple can supplement mathematics learning and, what is more, can do much of the mathematics for the students. That is certainly true. What is missing in this book is just how will Maple, say, actually help students understand mathematics when the students are still learning the math.

Any computer algebra system can solve equations and plot functions. These operations are simple and students can type a formula (with the correct syntax) to tell the program to plot it, and presto! the graph appears. Of course, students have to trust the program that the graph is correct. Does the graph correctly show the function around a singularity? Well, to know if it does, students have to understand singularities. The program cannot tell them that.

Maple can differentiate, integrate, and simplify expressions.  Is the form that Maple provides useful? Students must know what they need and what the various forms are that meet their needs. In fairness, Borwein and Skerritt make some of these points. They say that Maple can do these tasks and note that it is up to students to know how to ask Maple to provide what they want.

Still, with Maple (and other similar programs) so readily available, one wonders if there is any incentive for students to actually work to gain an intuitive insight into mathematics. On that score, the authors are silent. I wish the authors had spent time telling us not only what Maple can do, but why students who are just learning mathematics should use it.

The temptation is tremendous for students to skip the real work to have a true understanding of mathematics. There should be more emphasis on students knowing mathematics, not just how to type an expression to see a result. This issue is not addressed in the book but it needs to be explored fully so that students know more than just how to use a program. Students, and non-students alike, should know when and why the results of the program work. Maple, for all its power, is powerless to tell them that.

Who's tracking you on the web? Find out with Collusion.

There is a new add-on for your Firefox browser called Collusion. I just downloaded it and installed in on my computer.  Collusion generates a network diagram of the website you visit and other sites from that one.  All of them collect information about you and share that information. Collusion a way to see who is tracking you.

Here's a snippet from my visit to Contentions, a political blog.

You can see the blog itself in the center.  What I didn't know, but now I do, is that Contentions shares my visit to them with 23 (count 'em!) other sites. Whoa! That's a lot of sites that know about me that I don't necessary want to having anything to do with them.  Some of these sites may be innocuous, but some are tracking me to use that information to make money or generate ads.  With the Collusions diagram on a tabbed page (you simply click on the Collusions icon on your Firefox toolbar at the bottom of the window) you can put your mouse over any node to see what the node is. Also, Collusion gives you information on

It's not clear to me what to do about this, but the first step is to know that there's a problem. Collusion is showing us the problem.

Here's some of what Collusion reports on my visit to Contentions (with a cut and paste just below):

"When you visit commentarymagazine.com, it informs the following websites about you.

• google.com
• doubleclick.net
• addthis.com
• turn.com
• afy11.net
• openx.net
• wtp101.com
• revsci.net
• adnxs.com
• yieldmanager.com
• quantserve.com
• mathtag.com
• invitemedia.com
• jewishideasdaily.com
• contextweb.com
• scorecardresearch.com
• nrelate.com
• rfihub.com
• vizu.com
• advertising.com
• pointroll.com
• gwallet.com
• serving-sys.com"

Some of these sites I know about, and some I don't know about. But for all of them, I had no intention of telling them about myself. Yet, with a click to one site, these others know about me. That's scary.

Courses for Everyone

What do Stanford University, Princeton University, University of Pennsylvania, and University of Michigan have in common?

For one thing, these top tier schools now offer courses on-line and for free. If you haven't seen this before, click on the link and take a look at what's available. There are humanities, computer science, health care, and economics courses, to name a few subject areas.

I took the cryptography course taught by Dr. Dan Boneh and it was excellent. The course website has the slides for the lectures (pdf format and as a PowerPoint file) available for downloading. The videos can be watched (and saved!) in various formats.  In fact, in one video format, the video will pause so that the student can respond to a question in a box on the screen. The student can press a button to see if his answer is correct or not.  It's a great way to interact with the lecture (limited though it is) and keeps you involved with the material.

After a  week of lectures (usually about 5-hours, maybe less, of viewing time) there is a homework assignment. The homework was mostly multiple choice with a few fill in the blank answers. You can save the assignments as you do them and once you've completed the assignment, you submit it for immediate grading. The homework comes back with your answers graded and with comments about the answers you selected. Thus you learn why you were right (let's say you guessed the answer!) and why you may have been wrong.  The homework was due about a week, I think, after the material end date.  If you submit the homework after the due date, you lose 50% of the points.

At the end of the class there was a 13-question final exam with a two-week time period to complete.

Based on the one class I took, I signed up for three more. The cost is zero but there is a commitment of time and it's not small. Plus, the course goes week after week so there's a commitment of continual participation. Still, you have a chance to learn new topics in your home or office with no travel required.

The course was not as good as a traditional lecture. You can't ask the professor questions and you hear and see the lectures on your own without the benefit of peers nearby. There is a discussion forum and I found that useful to clear up ambiguities in the homework. But that's all I used them for; I think other students probably made greater use of the forums.

I encourage you to take a look at the courses, and if you find one to your liking, sign up. You have nothing to lose and can gain new knowledge in the comfort of your home or wherever you are.

Blogging again

Dear Friends,

It's been a bit since my last post but I'm ready to begin posting again.

My time was committed to other activities over the past few years and I didn't have the opportunity to write here. But that commitment is completed and I have more free time to write. I intend to do just that.

So, come back here soon and look for more posts and interesting tidbits of science and engineering.

David