Multinormal

Archive for the ‘Science’ Category

Mythbusters

Discovery Channel’s excellent Mythbusters dispute some of the moon landing conspiracy theories using a large vacuum chamber and demonstrate Galileo Galilei’s theory that, in the absence of air resistance, all objects fall at the same rate. The behaviour of a flag in a vacuum is interesting—intuitively you’d expect the lack of air to prevent movement (i.e. no wind, no flapping), but actually any small movement of the flag pole causes large and uninhibited movement of the flag itself. Cracking presentation of some basic science.

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Written by multinormal

August 31, 2008 at 3:42 pm

Posted in Science

Mirrors are Counterintuitive

Imagine you are standing in front of a bathroom mirror; how big do you think the image of your face is on the surface? And what would happen to the size of that image if you were to step steadily backward, away from the glass?

People overwhelmingly give the same answers. To the first question they say, well, the outline of my face on the mirror would be pretty much the size of my face. As for the second question, that’s obvious: if I move away from the mirror, the size of my image will shrink with each step.

Both answers, it turns out, are wrong. Outline your face on a mirror, and you will find it to be exactly half the size of your real face. Step back as much as you please, and the size of that outlined oval will not change: it will remain half the size of your face (or half the size of whatever part of your body you are looking at), even as the background scene reflected in the mirror steadily changes. Importantly, this half-size rule does not apply to the image of someone else moving about the room. If you sit still by the mirror, and a friend approaches or moves away, the size of the person’s image in the mirror will grow or shrink as our innate sense says it should.

From the New York Times.

It’s been years since I studied the physics of reflection—I was never much of a physicist anyway—and when I have time it would be fun to puzzle this one out, but a quick test shows that the article is likely to be correct about both phenomena.

It’s fascinating that we can can so fundamentally misunderstand everyday objects like mirrors. Another way of thinking about this would be to say that it is fascinating that, hundreds of years after the discovery of mirrors and the physical and mathematical properties behind them, our education system is so poor that the vast majority of people—myself included—aren’t sufficiently familiar with the relevant science to be able to answer simple questions like these.

Written by multinormal

July 22, 2008 at 12:41 pm

Posted in Science

Water (Ice) Found on Mars

The Phoenix Mars Lander has found what appears to be ice. The implication is that Mars may be able to support life, or may have been able to do so in the past. Their Twitter update reads:

Are you ready to celebrate? Well, get ready: We have ICE!!!!! Yes, ICE, *WATER ICE* on Mars! w00t!!! Best day ever!!

Written by multinormal

June 20, 2008 at 9:40 am

Posted in Science

Statistical Innumeracy & Civil Liberty

Cory Doctorow on statistical innumeracy, extremely rare events and civil liberty:

Statisticians speak of something called the Paradox of the False Positive. Here’s how that works: imagine that you’ve got a disease that strikes one in a million people, and a test for the disease that’s 99% accurate. You administer the test to a million people, and it will be positive for around 10,000 of them – because for every hundred people, it will be wrong once (that’s what 99% accurate means). Yet, statistically, we know that there’s [likely to be] only one infected person in the entire sample. That means that your “99% accurate” test is wrong 9,999 times out of 10,000!

And I heartily agree with his suggestion that:

If there’s one thing the government and our educational institutions could do to keep us safer, it’s this: teach us how statistics works. They should drill it into us with the same vigor with which they approached convincing us that property values would rise forever, make it the subject of reality TV shows and infuse every corner of our news and politics with it. Without an adequate grasp of these concepts, no one can ever tell for sure if he or she is safe.

Written by multinormal

June 15, 2008 at 10:50 am

Posted in Science