Tuesday, July 31, 2007

RIP Tom Snyder

RIP Tom Snyder. I always enjoyed the Tomorrow show and later the reincarnation on CNBC. In addition the pretty well-covered history in this article, I thought the tight, close-up shots they used were pretty cool.

Tuesday, July 24, 2007

Python Now

Okay, I've been using Python for a handful of months. I've gotten over the white space as langauge element business. I still don't favor it, but I get it. I personall still prefer braces or something like them for delimiting statement blocks, but I can live with the white space.

There are two unforgivable sins in Python.

The first is that instance variables and method names in an object class definition occupy the same name space! This means you can't have a variable called file and then a method to get/set it cadlled file(). As soon as you write a value to the variable (self.file = something) you've overwritten your method definition! Am I missing something here?

So you either have to use the built in direct access obj.file = something which you can do directly to set (and get), but you've lost the ability to massage data as you set or get it. Or you have to resort to obj.get_file() and obj.set_file(), or a method that does both.

Okay, I forgot what the second one was.

Update 18 Oct 2007: Okay, there is a way. See this post.

Wednesday, July 18, 2007

Crossing the Rings of Uranus

From Sky and Telescope, the Earth will cross the rings of Uranus for the first time since their discovery!

On Thursday, August 16th, Earth will cross the equator and ring plane of Uranus, and astronomers all over the world will be on watch. The unusual geometry offers a unique view of the planet's atmosphere, satellites and ring system.



Uranus's orbital period of 84 years means that we get ring-plane crossings only every 42 years. During the last one, in 1965, little was known about the distant planet, the ring system hadn't been discovered, space telescopes sounded like science fiction, and the 5-meter Hale telescope on Palomar Mountain was the world's largest.
Seth sent over this interesting take on the Internet.

Periodic Table of the Internet

Sunday, July 15, 2007

Comet Linear C/2006 VZ13


From Sky and Telescope:

Comet LINEAR (C/2006 VZ13), now crossing through Draco and Bo├Âtes, has far exceeded expectations. It was originally predicted to peak in brightness around magnitude 10, a pleasant spectacle for people who enjoy viewing faint comets through telescopes. But the latest magnitude estimates range from 7.5 to 8.0, making it an easy sight through 10×50 binoculars in a dark, transparent sky.

As of July 10th, the comet appears as a bright, round fuzzball roughly 8' across, with little hint of a tail. It will probably peak in brightness shortly after July 14th, when it comes nearest to Earth. Then it should fade gradually until perihelion, its closest approach to the Sun, on August 10th. But it will be disappearing into the evening twilight by the end of July.

Saturday, July 14, 2007

Who's the Emptiest?

So after the amazing web page, Seth and I embarked on a discussion of emptiness, where I claimed:

Other things, the Solar System, and even galaxies are similarly sparse. I find it fascinating that two galaxies can pass through each other with probably no stars colliding. (Gas, however, is a different matter, uh...so to speak, and gravitational, tidal forces are really, really a different matter!)

Which led to an interesting question. Which of these is the emptiest? My first intuition was that the average distance between objects, cubed, would give a rough indication of emptiness. Now, as I write this, it's obvious that emptiness is just density. In this case we're talking about particle density (things per cubic-length) and not mass density (grams per cubic-length).

Here's my first, rambling shot at the question.

As a start, the Sun is about 100 Earth's in diameter but the nearest star is four LY away which is about 24e12 miles. The earth's diameter is about 8000 miles, right? (I never can remember, but we are headed east at about 1000 mi/hr meaning the circumference is about 24,000 miles and over pi * d gives 8000 as d).

That make the Sun about 8e5 miles in diameter. So the nearest star distance is 24e12 / 8e5 = 3e7 diameters.

The web page you sent says the proton diameter to atom diameter ratio is about 1e5 so that makes a galaxy maybe 300 times emptier [sic] (3e7 / 1e5 = 3e2), or taking it in a volume sense, (3e2)^3 = 9e6 =~ 10 million times emptier. Wow. I wonder if that's right...

Now take the Solar system. If the Sun is 8e5 miles in diameter, we know the earth-sun distance is about 93e6 miles. 93e6 / 8e5 =~ 12e1 = 120. So the Earth is only about 120 solar diameters away so the solar system isn' t nearly as empty as an H atom. By volume 1e5 / 1.2e2 =~ 8e2. By volume (8e2)^3 =~ 6e8 so the atom is 600 million times more empty!

Neptune is at about 35 AU I think so that makes it about 4000 diameters, still less ``empty'' than an atom.

H-Atom Scale Model - 11-Mile-Wide Web Page!

Seth sends this link that is the coolest, most clever, and shocking thing I've seen on the web!! It's a scale model of a hydrogen atom.

It's a relatively simple web page with an electron as a single pixel, a proton as an image 1000 pixels across, and enough pixels between them that, at 72 pixels/inch the web page itself is 11 miles wide!!! That said, at least in Firefox it renders instantly and you can easily scroll to the right where the electron is.

Fascinating!!

China Practices Weather Control

This is a fascinating story of China practicing weather control.

Basically they're seeding clouds with silver iodide, but on a fairly large scale. Using anti-aircraft guns is an interesting approach.

Tuesday, July 10, 2007

Monday, July 09, 2007

Monolith

After something like 15 years, I have stopped receiving email on Monolith. A few minutes ago I changed the forwarding address in LDAP to forward email off-campus exclusively.

Monolith began as a NeXTslab computer on my desk top. It was my main workstation from the early 90s until maybe about 1997. The system was first set up in my office in Uppergate House, then made the move to Cox Hall. It also went with me for the brief stint in the University Apartments Tower penthouse. Sometime in 1997, when I moved from Cox Hall to the North Decatur Building, Monolith's soul moved to a SPARCstation 5 and Solaris 2.5.1. In later years it evolved into an Ultra 10, then a Sunblade 150. The OS probably made its way through Solaris 2.6, and maybe Solaris 9. I don't recall if it was ever Solaris 8.

For the past few years, Monolith left my main workstation and became a more humble Debian Linux box running on a Pentium II system with 96 MB of RAM and a 4-GB hard drive. It's been serving it's main duties as an email server (running Exim for the MTA and Cyrus IMAP), and a web serve running Apache. For the past six months, Monolith has been hiding in the machine room on the fourth floor of the Woodruff Library.

Today I'll shut down the web server and email services and then will remove the box sometime this week.

Saturday, July 07, 2007

Keyboard Type in Ubuntu

Here's a question: Where is the keyboard type stored in Ubuntu Linux, or in Linux in general?

The answer is, in the file /etc/default/console-setup.

Friday, July 06, 2007

Upstart Replaces Init

Though I knew that the Ubuntu project had replaced init(1) with a new scheme, I've largely ignored it until now.

Here's a nice article on the rationale behind the change.

Here's the Upstart home page.

Monday, July 02, 2007

Quote of the Day

Okay, this is a good one. From Michael's signature…

First we thought the PC was a calculator. Then we found out how to turn numbers into letters with ASCII — and we thought it was a typewriter. Then we discovered graphics, and we thought it was a television. With the World Wide Web, we've realized it's a brochure.

Douglas Adams

Sunday, July 01, 2007

Six Scientific Questions

From the Observer Gardian.

We asked three writers, three scientists and two broadcasters to answer six basic scientific questions, and their answers appear to confirm the arts/science divide.


This was a fun, and somewhat disturbing exercise.

Can you answer these questions? (Before you look at the answers and/or read the article).
  1. Q: Why does salt dissolve in water?
  2. Q: Roughly how old is the earth?
  3. Q: What happens when you turn on a light?
  4. Q: Is a clone the same as a twin?
  5. Q: Why is the sky blue?
  6. Q: What is the Second Law of Thermodynamics?
In my own case, I had the most trouble with number four (the clone question) and a bit of trouble with number one. The rest I had ready answers for.