Friday, November 20, 2009

The Days, Months and Years of Our Lives (FPOTW)

Small moments... that is what our life is comprised of. 





We all see the reports of how much time the average person sits in front of a television, or how much of our lives are spent sleeping, or driving to work. But the most mundane and trivial aspects of our existence pile up to large numbers.
How much time do you spend on the toilet? How about brushing your teeth? Picking your nose?
Here are a few ponderables to while away some of the time left over in your life. After considering these, spend some time coming up with some of your own.

---- Start Fermi Problem ----

How much time does one spend picking their nose?

How much time is spent brushing ones hair.

Brushing teeth?

Masturbating?

Crying?

Laughing?

What is the total percentage of your life that your eyes are closed?

Sitting on the crapper?

Doing Fermi problems?

---- End Fermi Problem ----

Damn... my nose itches...

Sunday, November 15, 2009

The 10 weirdest physics facts bull$hit

Twitter...
Seems to me a way of mindlessly parroting what thousands before you think is cool and trendy. Heaven forbid you actually pause and think for a second about what you read.



Take the latest #physics re-tweets about an article called The 10 weirdest physics facts, from relativity to quantum mechanics.

My god... for the last week this has been re-tweeted numerous times. Don't any of these people actually read the comments to this article pointing out the obvious factual errors? Do they even stop for a millisecond and perform a sanity check?

OK people, here is a small tutorial on how to think critically about such an article.

1. Approach everything you read with a modicum of skepticism.

Any article that states weirdest physics facts causes my bullshit meter to twitch. "Facts" is a term most physicists like to avoid writing down, even if they secretly believe in those facts. All facts are open to the possibility of being disproved. Just design an experiment to test the "fact".

2. Check the authors credentials.

When I read in the opening paragraph the following, my bullshit meter starts to really twitch:

"The humanities-graduate writer of this piece would like to stress that this is his work, so any glaring factual errors he has included are his own as well. If you spot any, feel free to point them out in the comment box below"

A humanities graduate writer is writing a piece on physics? Humm... it is a pretty good bet they don't know enough to write cogently about the subject, but that is ok, they are simply going to write an article for mass consumption to promote science as cool and interesting.  Thanks for the help Mr. Humanities-graduate writer.

And don't give me any crap about Einstein being a patent clerk etc etc. Crackpots use this argument in support of their bullshit physics assertions. Einstein had the training and the credentials. For every Ramanujan out there, who literally came from nowhere (but still had the training) there are a million others who put in vast time and effort to learn the subject. Don't pander to the exceptions. 99% of the time it is safe to be very skeptical of anything a humanities-graduate writer will write about physics.

Also...
WTF? Are we, the readers supposed to correct the writers misconceptions? Whatever happened to checking your facts before posting? The writer is making the assertion, and in science it is up to the asserting person to make his case.

3. Perform a Sanity Check on one of the topics.

Lets make this easy, and lets look at the very first one:

If the Sun were made of bananas, it would be just as hot
"The Sun is hot, as the more astute of you will have noticed. It is hot because its enormous weight – about a billion billion billion tons – creates vast gravity, putting its core under colossal pressure. Just as a bicycle pump gets warm when you pump it, the pressure increases the temperature. Enormous pressure leads to enormous temperature."

Wow, where to start? Oh yeah, how about starting where he states that the sun is hot because of its enormous weight.

It is very easy to calculate the amount of energy the sun produces. This number was pretty well determined over a hundred years ago. This number is about 4E26 J/s.

We can trivially calculate the gravitational energy of our "banana sun" by assuming that the sun was assembled via self gravitation of bananas falling toward a central point from a very large distance.
The potential energy of a sun's mass of bananas falling from infinity to the radius of the sun is:



http://en.wikipedia.org/wiki/Sun gives us some facts about the sun:

M ~ 2E30 kg
R ~ 7E8 m

http://en.wikipedia.org/wiki/Gravitational_constant

G ~ 7E-11 m^3/(kg s^2)

E_G ~ 4E41 J

Therefore the gravitational energy of the bananas can produce the energy radiated by the sun for a total of 31  million years. Considering that the sun has been shining for about 5 billion years so far, we can see that the authors statement is the monkey digested remains of all those bananas.

The sun is powered by nuclear fusion. The banana's are made of the intergalactic vomit spewed by a dying star, in other words what the star could not consume. Chances are a banana sun would not last comparatively as long.

4. Don't waste your time.

At this point we have direct empirical evidence that the article will be bullshit. If the very first entry on the 10 "facts" is trivially disproved, then you have better things to do than waste any more time with the article. Go crack a book on physics. There are literally thousands of good texts or even popular accounts out there. Hell, even Scientific American is better than some random article on a internet news site.

And please stop re-tweeting this bullshit.