This blog suspended until further notice

I’m going to admit the obvious: that other responsibilities (such as the job that pays me cashy money) prevent me from keeping up with blogging. The content of these posts takes a lot of research, and I simply don’t have the time or the energy to do it any justice.  Therefore it is with a sad heart that I bid you farewell for now. Thank you to those who have been faithful companions on this journey – your comments,  insights and support have been valued more than you may know.

Sapere aude, friends.

Yuletide reflection

I’m a big fan of Yuletide/Decemberween/Wintermas/whatever you want to call it. It’s a great holiday: getting together with family, exchanging gifts and tucking in to a three-course meal that leaves everyone mildly incapacitated. My family has, as all families have, its own special traditions that I look forward to every year: that everyone has to help out with the meal in some way, that presents are only given after the main course and before dessert to allow some modicum of digestion to take place, the phoning of family living overseas to wish them personally, and the requirement that the youngest child who can read gives out all the gifts one at a time to the waiting family, sitting crowded around the tree. That some religious people celebrate the birth of their prophet on that day is a coincidence that is generally not taken into account, for which I am enormously grateful.

Yuletide for me starts weeks in advance, with the all-important tasks of discussing and planning the menu, and with the purchasing of gifts. The careful selection of a good gift is by far the most challenging and satisfying aspect of my Yuletide. They say that it is better to give than to receive, and never is that more true than when one receives a truly disappointing gift. There is always the distant relative or elderly aunt who invariably gives you either something inpersonal like socks, or something truly offensive, like a bible. Case in point this year was a 2008 astrology calendar from a female relative of my significant other, complete with daily predictions for the year ahead. This would be from the same person who presented me last year with a book on Feng Shui and another on Dream Interpretation. Gifts like these make you wonder if the person is shopping for you, or for themselves.

What do you do in these scenarios? Well, in the spirit of the season, you smile and thank them graciously, as if you had just received something wonderful, thoughtful and exciting, that you cannot wait to dig into. This can be difficult, and I was very thankful this year that the gift was actually not presented in person, nor did I have to thank the giver in person, so I was spared that trial of forced good nature. On the down side, it only means that next year I will receive something similar, probably a guide to homeopathic remedies or something by Deepak Chopra.

Oh well, another yuletide came and went in exactly the way I expected it – chaos, tradition, good cheer, great food, and mostly good presents. Here’s looking forward to next year.

On Notice

I think it’s time for Stephen Colbert to put some people on notice:

I’ll be away for a while

I have the next week off, so don’t expect to hear much from me during that time, unless my ADSL is magically connected early. Since that’s about as likely as pigs flying, homeopathy being scientifically proven, and Zuma being found guilty of corruption, I’d say don’t hold your breath.

In the meantime, keep yourself entertained by reading some of the blogs in the sidebar.

Quote of the moment

There are reasons I love to read Pharyngula, and this is one of them:

I suspect anyone caught needing to consume a tiger’s erectile organ is deeply inadequate, not just in the crotch, but the brain as well.

I think someone is taking the piss

There’s a woman called Dr. Orzack who apparently specializes in the psychology, treatment and cure of Computer Addiction. I think the entire site must be a spoof, and it’s not just because of the corny signs that you might be addicted to computers. Look at this picture of the good doctor:

I put forward the motion that this is not a psychologist, nor is she even a woman. In fact, someone is taking the piss. Who? Look below the fold if you think you know.

We’re all moved in

I’ve semi-successfully imported all my blogspot posts. Because of the time of posting, it’s resulted in the ‘we’re moving’ post occuring after the ‘welcome to wordpress’ one, but i think that’s a weird little space-time continuum loop i can live with (the universe doesn’t appear to have collapsed in on itself). Also some of my image placing seems to be b0rked on the old posts…. if i ever have time i’ll go back and fix them.

One thing i did bother to do was go back and categorize all the Midweek Cuckoos, so now you can grab all the past ones by selecting the approprate category. All the other imported posts are under Uncategorized. I doubt i’ll ever have the time to go back through all of those…

Anyway, i’ve unpacked, i’ve put most of the boxes away, and my toiletries are all in the bathroom. I’m here to stay… at least until i get a better offer.

We’ve Moved

That’s it, blogspot is driving me up the freaking wall. Party’s moved to WordPress, people.

Yes, Mr Angry, you were right.

Lunch and the Intartron

Yesterday i was so busy i didn’t eat lunch, which i feel is about the right kind of busy. Today is a lunch day at work, though (tuesdays and thursdays lunch is provided) so i’m taking quick break to eat lunch and blog. This post may be somewhat incoherent, as i’m just taking down thoughts while reading my usual selection of favorite sites.

Bad Astronomy has a link to a cute optical illusion. Nice.

Ugh, the news is just too much to mention. Over the last few days south africans have been murdered left, right and center, and yet our minister of safety and security still will not apologise for saying that south africans who winge about crime can get out of his country. It makes me so mad i can’t even begin to comment.

Skepchick has a couple of funny articles about church building without a permit and some guy who claims he can read your baby’s palms while it’s still in the womb. Kooks and the religious, always good for a laugh.

Ah, Pharyngula is scathing as always. People who call themselves educated and don’t know the name of Nyarlathotep deserve our scorn.

Hmm, maybe more later. Time to get back to work.

What is this, the Straight Dope?

Bast asks:

I have a question, with regards to the possible impact crater found in antarctica. If an asteroid 50 km in length slammed into the earth could it alter the orbit around the sun? and by alter I mean not just a little wobble but actually push the earth further away (or closer I suppose depending on whether it hit at night).

The full solution to this problem is likely to be quite complex, so forgive me if i do a bit of handwaving and back-of-the-envelope calculating here. The way i see it, at the bares bones we’re talking about a collision. When it comes to collisions, at the very least we know that momentum will be conserved so, to start with, the important factors are mass and velocity. If i know the mass and velocity of the two bodies (the earth and the impactor) prior to impact, i can use those to work out the final velocity of the earth after impact. But how does knowing how fast the earth is moving help me?

Well, when it comes to orbits there is an inverse proportionality between orbital radius (the distance of the orbit from the sun) and orbital velocity. Decrease the earth’s orbital radius, and it will increase it’s orbital velocity. Similarly, if you decrease the earth’s orbital velocity, it will increase it’s orbital radius (this what makes it difficult for shuttle pilots to manoeuvre in orbit – changing your speed can have undesired effects).

Knowing the change in velocity allows us to calculate the change in radius as a result of the change in velocity, assuming conservation of momentum. This is of course the simplest way of getting an order of magnitude answer – i could go to a lot of effort calculating the exact orbital mechanics, but for this i think we just want a feel of how big a change can be made. I’m going to make assumptions like a circular orbit for earth, and a constant orbital velocity for earth, anyway.

So, we are going to need to set some bounds to the problem. How massive is a 50km wide asteroid? How fast can it be going when it hits us? How elastic is the collision. The following are the extrema i’ve selected for each variable:

1. Density for observed meteoroids is between 3-8g/cc.
2. Impact (i.e. relative) velocity of impact has been recorded in the range from 11-72km/s.
3. The collision can range from perfectly inelastic (all impactor’s energy released, final mass = earth mass), to perfectly elastic (no energy released by impactor, final mass = earth mass + impactor mass).
4. Direction of impact can range from travelling in exactly the same direction along the orbital path, to travelling in exactly the opposite direction along the orbital path.

I calculated the range of possible values for all combinations of these extrema, and came out with a range of variance in final velocity from 0.000094% increase to 0.0000067% decrease. So on order of magnitude we’re talking roughly a 0.00001% change one way or the other, depending on how the impact happened. Since orbital velocity is inversely proportional to orbital radius, this translates to a 0.00001% change in our distance from the sun.

The question is, how big a change is this, really? Is it enough to significantly affect life on earth?
One of the measures of whether life can exist on earth or not is the so-called Habitable Zone, the range of distances from a star where water is in a liquid state. For our sun, this is in the range 0.7AU to 1.5AU (one AU, or astronomical unit, is the distance from the earth to the sun). We would therefore require at least a 30% change in our orbital distance to radically affect all life on earth.

But all life on earth isn’t us. We would be severely uncomfortable at temperatures that many bacteria would thrive in. How big a difference is 0.00001% to us? Another way of looking at it is to measure the change in energy we’re receiving from the sun. This is usually measured in terms of the Solar Constant, the amount of energy received by 1 square meter of the atmosphere when the sun is shining directly at it. This is naturally related to the distance from the sun. Given the numbers from the previous calculation, we’re looking at a variance in the solar constant on the order of 0.000002%. Again, how big is this in terms that mean something to us? Normal changes in the earth’s distance from the sun due to axial tilt, precession and orbital eccentricity (the Milankovitch cyles) are thought to be a factor in the causation of ice ages, but the factors involved create changes on the order of a few percent, much larger than our variance.

In other words, any change in the earth’s orbit due to a collision is going to be negligable, even for an object as large as 50km across. Even then, an object of this size impacting the earth is extremely rare (there are no measured Near Earth Asteroids greater than 25km across at present). At the end of the day, it’s the dust kicked up by the impactor that has the real long term effect – it only takes a 2km meteor to throw enough ejecta into the atmosphere to result in serious environmental damage, and anything larger than that is guaranteed to cause mass extinction.

Here’s a good page on meteorites, with plenty of good links.

And here’s NASA’s comet and asteroid impact hazard site.

Proviso: any and all calculations made in this post may be completely and utterly incorrect.