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The other is in my large consumption of chocolate, particularly in the form of chocolate milk. I'm not sure if this is a real "addiction" or not, what I do know is that I have a hard time getting through the day with no chocolate, whether it is mixed with milk or not. I consider chocolate a food, not a drug, but some people would disagree with this.

Chocolate is mostly a food, but it does contain small quantities of drug compounds, including caffeine and THC-like chemicals. I've heard that you'd need to eat many pounds of chocolate to be equivalent to one joint, but then marijuana usage among my friends varies by probably two orders of magnitude, so perhaps some people are more sensitive than others. Also, empirical data suggests that women are much more sensitive to chocolate's mood-altering effects than men.

For more info, here are some choice links from this Google search:

• Exploring Chocolate
• Science News Online
• Psychiatric News

Ok. This reply is going to cover the three replies I've received so far. I apologize in advance for the long post. And to anyone thinking of dropping out of High School, stay it, if only for the math (you'll see why later). Bear with me.

craw wrote: "What are the sources of ambient noise in the oceans?...I'm going to assume that you are talking about high frequency sources, given that you allude to blockage."

Actually, I was referring to flow noise. Flow noise occurs because, well, water flows. When trillions of molecules of water move and tumble and collide, they make noise. Depending on water speed, depth, and temperature, water can have all three frequency ranges...

craw wrote: "However, the propagation paths will be complicated due to the vertical sound speed structure and the variablity of this function. Note that rain and breaking wave sources will be broadly distributed (including those close to the sensor)."

Correct. This is complicated further by the position of the thermoclyne(sp?).

When water is of two contrasting temperatures, the cold water will sink and slow down. It forms a fairly flat `layer'. On top of this is the warmer water. Water on top of the layer tends to move faster and have more variety of currents. Therefore, detecting sound below the layer from above the layer is more difficult than detecting sound above the layer from below the layer. Since the layer sits at between 200 and 600 feet, it's easy to stay underneath it.

Now, if I'm 100 feet below the layer, and the Typhoon is 100 feet above the layer, and the chop is about 20 feet (think mid-Atlantic in fall), I will probably have a difficult time hearing her.

If the chop is closer to 5 feet, however, and all other factors are equal, I should be able to hear the Typhoon if I'm +- 3 degrees to either side of her (like this: /\).

Below the layer, these factors are mitigated.

craw wrote: "If you are talking about low frequency signals, then the dominant source is shipping, earthquakes, and whales."

And flow noise (below the layer). Remember that the currents under the layer run at about 3 to 6 knots. These currents are not nearly as fickle as the currents above the layer, therefore, we can depend on them (a bit more).

craw wrote: "If natural fluctuation occur, then how do you differentiate betweeen natural fluctuations and the "silence" of a sub?"

If the current is coming from the East, and there's a Typhoon to my East, then depending upon the difference between our respective `altitude' (can't remamber the proper word) and distance between us, I may be able to detect her, either from an absence of flow noise, or because of a variance in what I'm expecting to hear. The point is that I should hear x amount of y different types of noise. If x is ever more than a standard deviation off, I have cause to investigate. More on this later.

Ozwald wrote: "When moving air hits a round object (or an object boing through air), it tries to go around and continue on its original path."

But is does not do this perfectly. See below...

Ozwald wrote: "Ever drive down a highway at 100 km/hour behind a truck/trailer? Being directly behind one causes your car to bounce side to side from the truck's turbulance until you finally get atleast beside the cab of the truck."

You have proven one of my points for me. (Keep in mind that Typhoons can't (and wouldn't) go 100 kph) Ok, when you're behind that semi, everything concerning the air is totally different than it would be if you were not behind that semi. Because it is there, and because it is causing a disturbance several meters behind itself (you don't tailgate, right ;-), you notice that it's there. That's one thing to look for.

Another point: have you ever sat in the back of a pickup? If it's going slow, the air is calmer right next to the cab than it is by the tailgate (it's much easier to light a cigarette there). If you're looking for a sub that's going reeeeeealy slow (as boomers are want to do), they will leave `holes' in the water at those speeds. How big a hole is a function of the speed of the boat (I wish I could remember my trig - all two weeks of it before I dropped out. Thought I forgot, didn't you?).

Diagram:

***************************
***************************
************.**************
**********...**************
*******...../\*************
******.....|T |************
******.....|Y |************
******.....|P |************
******.....|H |************
******.....|O |************
******.....|O |************
******.....|N |************
******.....|__|************
******.........************
********......*************
**********..***************
***************************

Legend:
* = Flow Noise
. = Hole in the Water (quiet water)


Because of this hole in the water, the noise that reaches the sonar will be different for roughly that shape (as in the diagram above) for a certain distance at a certain speed yadda yadda ad nauseum.

Ozwald wrote: "A aerodynamic object like a plane, submarine, trout, etc. are designed not to cause turbulance from movement alone,"

Number one: They may not be designed to, but they do. Remeber that air is a liquid too, for the purpose of this exercise. Liquids have this nasty property called adhesion. Because all of the molecules of (water|air) are togeter in a finite space, moving one molecule will case it's neighbors to move. This is called drag. For a better explination of why this is a problem and possible solutions (for aircraft, anyway), look up the Laminar Flow wing here and here).

Ozwald wrote: "but it is impossible not to if it is maintaining a speed or accelerating."

Subs have to move. Kinda like sharks. Well, they dont have to, but they need to. Why? Three reasons (off the top of my head):

• To prevent broaching. Subs are designed to be a tiny bit boyant. That's why when they move normally at a constant depth the diving planes are at a slight down angle (usually a degree or two). If the sub stops moving, she can no longer totally control her depth. That's a Bad Thing ©
• Steerage. Almost the same problem as above. Any good skipper will try to go no slower than 2 or 3 knots. That way, the boat will still be responsive to steering input. Why? beacause...
• Sonar equipment only works in cones or echelons. Problem: you cannot cover the entire 360 degrees around a boat with one passive sonar. Solution: have multiple passive sonars. Most boats have a front array, lateral array, and some (I know the Los Angeles boats do) have towed arrays. For those to work, the boat needs to be able to move the arrays around (purposes of triangulation and all).

Therefore: Subs will never not move. Boomers will usually hold a really slow speed, but it's constant. Laminar flow problems and adhesion cause disturbances in the water, especially under the layer. And a really good sonarman can detect these disturbances.

*whew* I'm done now...


Jedi Hacker (Apprentice) and Code Poet

i've read just "Surely You Must Be Joking Mr. Feynman!" book and i do not remember teller being mentioned there ...

... but using astalavista babe search engine i found this:
From Part IV "Los Alamos" - teller is mentioned there, but no feynman's opinion on him
atomic memories - some guy there leaves a note: teller was profesor ... (Ctrl+F and type teller :) [this is some survey or what about nuclear bombs, not related to feynman or teller directly]

seeing the content of firts link it would be fine to read the book again, maybe there is something more about teller from feynman.

maybe somebody relse emembers better?