Friday, September 29, 2006

Stupid bloggers

Ok, so Dummy McDummerson decides to post:

6 Commonly Believed Things That Are Wrong

No sweat.  Neat concept.  The list is probably short.

The problem is that he lists these 6 things:

  1. Centrifugal Force
  2. The sky is blue because of the ocean or space
  3. Extra Dimensions
  4. Nuclear power plants can explode like a bomb
  5. Microwave ovens (or other electronics) can cause cancer
  6. Medieval people thought the world was flat

And then goes on to either explain the correct thing incorrectly, misrepresent the incorrect thing, or just plain provide a wrong answer.  Needless to say there are nearly 100 comments to Dummy’s post.  I’m not going to post the link because I don’t want to add to the dumbness.

However, I’m willing to look at the things he screws up.

So lets look at it (remember, I’m an accountant).

1.       Centrifugal Force.  He says:

There is a lot of confusion about this one. Some people think that the centrifugal force is what causes water to stay in a bucket when you spin it around or pushes you against the door when you take a sharp turn in your car. That’s completely wrong, but not helped by its name, which means “center fleeing”. Some people also call centrifugal force a fake force. This is also wrong. So what’s going on?

When something moves in an circle, it is accelerating. This acceleration is called centripetal, which roughly means “pointing toward the center”. Because acceleration is a vector, it needs a direction, and centripetal acceleration is always pointing toward the center of the circle, hence its name. Thanks to Newton, we know that F = ma, so when a mass accelerates there’s a force. But that force is not what pushes you out, because it’s actually pointed toward the center of the circle. So what’s going on?

Well, Newton also explained this one. What pushes you out is Inertia. Because your body resists changes in its direction, when it undergoes centripetal acceleration it wants to keep going in a direction tangent to the circle. That’s what pushes you against the door and keeps the water in the bucket.

So what about the “fake force” part? Well, in a normal reference frame, the centrifugal force doesn’t exist. But in a rotating frame, it most certainly does. So while we might not need it most of the time, examining forces from a rotating frame requires it. It’s not fake at all.

 

Ok, so it’s not a force any more than getting punched is a “force”.  It’s a term to explain what’s going on in a centrifugal system with vectors and direction and force acting on an object and inertia and stuff.  Centrifugal Force does not keep water in a bucket when you spin it around.  A bucket is denser than water and therefore water does not slip through the walls of the bucket just like you can’t pass through a wall (unless there’s a door).  Centrifugal Force describes the several events that coincide (acceleration, redirection, etcetera) to keep the water in the bucket.  If those forces do not coincide, you get wet.  Maybe that’s what the misconception is, that people think there electromagnetism, gravity, strong, weak, atomic, and “centrifugal” force within atoms.

 

2.       The sky is blue because of the ocean or space.  He says:

I cannot confidently say that this is a common belief everywhere, and I sincerely hope it isn’t, but when I was in high school a large number of people did believe it, and no one knew what really makes the sky blue. I won’t even go into why it’s idiotic to think this, because it’s so obvious, but the real cause is interesting and not very well known so I will elaborate on it.

The cause is known as Raleigh scattering. What happens is that the blue wavelengths of the light from the sun are absorbed and then radiated by the gasses in the atmosphere, while the rest of the spectrum remains unaffected. This radiation happens in all directions, meaning that the entire sky looks pretty much the same shade of blue. This is also why the sun looks yellow instead of white, enough of the blue end of the spectrum is removed for it to appear yellow.

It also affects sunset, causing more of the shorter wavelengths to be filtered out as the sun’s light has to pass through more of the atmosphere to reach you.

I cannot personally say that I’ve ever met someone who seriously believes this.  Nor can I honestly say that I’ve ever met someone who buys the “Raleigh Scattering” explanation as he gives it.  Why is the sky blue?  As I understand it (remember, I’m an accountant) it has something to do with refraction and reflection.  Air is clear (so is water).  The red comes through the atmosphere and some of blue reflects.  That’s good enough for me.  It’s most decidedly not the reflection of water on the sky or vice-versa.

 

3.      Extra Dimensions

He talks about xyz + Time, then tries to talk about string theory.  I’m not reposting the original because it’s all theory stuff and can’t be proven one way or another.  What it boils down to is there are 3 spatial dimensions, plus time, and from our point of view there are no other useful data points to specify where or when something occurred because if an event occurred it’s assumed it occurred in this dimension (which we can perceive) and not some other dimension that we can neither perceive nor prove exists.  It’s like saying “someone just crapped on Pluto”.  We can’t prove it happened, we can’t prove it didn’t.  So, when we say “someone just crapped” we assume it’s either here on earth or possibly in the space station, but nowhere else, so I don’t have to say North America, US, Texas, Houston, 2200 Main…  oh yea, on earth.

 

4.      Nuclear Power plants can explode like a bomb.  He said:

I know some extremely intelligent people who believe this, and it’s rubbish. Nuclear power plants don’t have anywhere close to the fissile material needed for the runaway reaction like a bomb. Modern power plants can’t even meltdown like Chernobyl did. It’s actually a great irony of history that the same day that Chernobyl’s reactors overheated the same test was done here in the US, and the reactor passed with flying colors. Safeguards in place today make overheating virtually impossible. The pollution from coal plants is far more dangerous than nuclear power ever will be, but people seem so irrationally afraid of nuclear power that it doesn’t matter that it’s the safest and cleanest means of generating energy (at least once we have a good waste disposal plan, and there are many in the works).

First off, he’s wrong.  Anything can explode like a bomb.  A coke bottle can explode like a bomb.  I think what he meant was “Nuclear power plants can explode like a thermonuclear bomb”.  That much is quite untrue.  Regular fission plants cannot explode like thermonuclear bombs because nukes work on principles of FUSION and power plants work on principles of FISSION.  So, right from initial science power plants can’t go Hiroshima on us.  Can they blow up?  Sure.  If the core melts down superheated steam has to escape somewhere and the place goes kablowey.  If I take a can of beans and heat it up unopened it blows like a bomb.  That’s what happens.  Now, the beans don’t go thermonuclear on me.  I have to eat them for that to happen (yuk, yuk).

That said, a meltdown is quite unlikely.  You’re safer living next to a nuclear plant than driving to work.  Of course, you’re much more likely to survive the long term consequences of a car crash than a nuclear meltdown in your neighborhood.  Good thing nuke reactors are pretty safe.

 

5.      Microwave ovens (or other electronics) can cause cancer.

This one he actually gets right and the simple suggestion that you can get cancer from using a microwave is completely absurd.  And you’re far more likely to get in a car wreck because you’re talking on your stupid cell phone than you are to get cancer from talking on your stupid cell phone, so put it down while you’re driving before I run you off the damn road!!!

 

6.      Medieval people thought the world was flat.  He says:

No, they didn’t. This was made up more or less out of thin air by Washington Irving in his horrid biography of Christopher Columbus. I haven’t the faintest idea why this has become so widespread, since there is ample evidence going against it, but unfortunately it’s still taught.

Look, people today think the world is flat.  There’s not many of them, but they’re out there.  They think we didn’t land on the moon, Kennedy is still alive, microwaves give you cancer, the sky is blue because of the ocean, nuclear plants will create mushroom clouds, water stays in bucket by magic, and the World Trade Center attacks were an elaborate plot to start a war of genocide.  If there are idiots like that today with all the modern technology and information available to everyone on the planet, what makes you think people 500 years ago weren’t equally (or moreso) ignorant?  People thought the world was flat.  SOME EDUCATED people may not have thought the world was flat, but SOME EDUCATED people is not EVERYBODY.

0 Comments:

Post a Comment

Subscribe to Post Comments [Atom]

Links to this post:

Create a Link

<< Home