Schrodinger's Cat

Our faculty is having a funwalk tomorrow, and as a school (School of Physics) we go as a group, and have T-shirts designed. I was asked to find some design for the tshirt. Well, I have kind of had this idea in my mind for the past few months that Schrodinger's Cat would make for a great physics themed t-shirt. I spent a bit of time trawling the internet for some ideas, and some really nice pictures popped up. Anyway, it got me to thinking, how many people actually know the story behind  the unfortunate feline companion of Erwin Schrodinger.

Erwin Schrodinger was a big player in the early development of quantum mechanics, and is responsible for providing the world with Schrodinger's Equation, which allows one to determine the time evolution of quantum states. I'll say no more about that. One of the underlying concepts in quatum mechanics is the one of probability, namely that nothing is certain. Our everyday understanding of how the world works, does not apply in the realm of quantum mechanics. For instance, if I drop a glass full of red wine onto the floor (shame on me), then we all expect that that glass would hit the floor, and spill. But, quantum mechanics predicts that there is a small chance of the glass passing right through the floor, and landing in the basement (either result is bad for me though).

Okay, so back to Schrodinger's Cat. Schrodinger proposed a thought experiment (meaning that he only conducted the experiment in his mind).  For this experiment, one would place a cat in a box, with a sealed vial of poison, and seal the box. The vial of poison is set to release its contents at an undetermined time. So, without opening the box, one has no way of knowing whether the cat is alive or dead. And so we can think of the cat as both alive and dead. Weird, but this is the kind of stuff that quantum mechanics deals with. It is a very complex field.

Anyway, this brings me to my tshirt design idea. I have attached the picture, which I think is from an episode of Big Bang Theory. Also, I should point out that the powers that be opted for a different design, but oh well. Now that you know where it comes from, you can see that it is a rather clever design.

NerdyGuy: Traffic Circles

NerdyGuy: Traffic Circles: I had an interesting, but not entirely unfamiliar experience this weekend. It surprises me that in Umhlanga, where traffic circles are so an...

Traffic Circles

I had an interesting, but not entirely unfamiliar experience this weekend. It surprises me that in Umhlanga, where traffic circles are so annoyingly prevelent, that so many of the local drivers don't understand how to use them. I was going around a traffic circle (I was going straight), much in the way that I have always accepted as correct, and some driver came around my outside, trying to go right. He slammed on breaks, missing the collision, but what made it worse, is that he had the nerve to hoot and use some unrated hand signals. Traffic circles are easy in principle, but there seems to me an inconsistent understanding on what do do if there are two lanes in the circle. My rule of thumb: If you are going let or straight, use the outside lane. If you are going straight or right, use the inside lane. If you are going all the way around (back the way you came) then use the lane you are most comfortable with, but you make very sure you don't obstruct any one when you exit, because no one expects this. Also, appropriate use of indicators is just polite.

But, as my girlfriend has revealed to me, there is an online source from a professional traffic adviser, which explains, with the aid of  a picture-video, exactly how to use them. Unfortunately this does not include any advice for the 360, which in my opinion, raises the most chance for a fender bender.

You can check it out at http://www.arrivealive.co.za/pages.aspx?i=2163. This is something which everyone needs to know how to do, even if you are from Gauteng where (based on what I have seen of their traffic circle etiquette) there are probably very few traffic circles.

Anyway, lets open this up for discussion. Post a comment of how you usually handle the 2-lane daemon (it should be automatic after all).

Cloning a disk using Linux's dd

As a scientist, it is pretty convenient to use linux for my work. It is a flexible, lightweight and not to mention free OS. Over the past 4.5 years of using this system, I have learn't a few handy things, but this OS never runs out of things to teach me. Today, I learn't about using dd to create a cloned hard disk. Now, you will of course need to know something about how linux manages disks and partitions, but hopefully the elegance of this will be evident even if you do not.

dd creates a byte by byte replica of a source to some destination (hard drive to hard drive, or hard drive/cdrom to an image file). The advantages of this are that it only sees 1's and 0's, not files. It will replicate partitions, and file distribution. There are some downsides, like it will preserve "fragmentation" of the drive, and empty space, will still take up space on the image, ie: creating an image from a 40GB drive will produce a 40GB image file, even if the original hard drive was half empty. But, when you want to be sure that your data is preserved, then these are a small price to pay.  

To use dd (which might need to be installed on your particular distro), you would use something like the following (from a terminal of course):

dd if=/dev/sda of=/dev/sdb

where if is the source, and of is the destination. The source can be anything like

/dev/sda; /dev/sda1; /dev/cdrom; /home/user/

and the destination can be anything like

/dev/sdb; /dev/sdb1; /home/user/image.img (hard drive image), or /home/user/image.iso (cd/dvd image).

You might already see how this could be used to create a hard drive image, or optical disk image, which can serve as a backup, or for replication onto several other devices.

Some tips on how to optomise this process are:

1: Change the blocksize to 1MB using "bs=1M"
2: Compress the image file using gzip (or pigz - a parallel version of gzip)

Go Linux!