Can you sink by blowing up your BC below 40m?

[blac86]

Obviously negative bubbles are why you need tec diver training to go beyond 40m.

 

[bowlofpetunias]

Bendimedes Principal

Any object, wholly or partially immersed in a stationary fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object...unless that object is below 40 meters and the fluid is displaced by air at which point the force vector is reversed and the object is no longer buoyed by any forces. Commonly referred to as "negative bubbles".

This phenomenon was discovered by Archimedes younger brother Bendimedes while he was researching early Greek halucigenics.

No no Negative bubbles are the smallest known blackholes. They were discovered by the famous Astronomer John Wheeler shortly after he discovers "Black Holes" in space. They are the only ones to be discovered on earth.

 

[boulderjohn]

I would not be too quick to dismiss the friend. He may well be repeating something he heard and believed without checking it out. It even may be a misunderstanding or a misremembering of something that is actually true.

Many years ago I heard someone call in to a very popular talk radio show and say that there is a bird that lives its entire life cycle inside a shark's mouth, getting its sustenance from the scraps between the shark's teeth. The caller was misremembering a popular biology class lesson. As an example of a symbiosis, the lesson talks about alligators and crocodiles allowing birds to pick out food scraps between their teeth--both parties benefit. As an example of commensalism, the lesson talks about fish that swim with sharks so that they can get benefit from the shark's sloppy eating skills--one party benefits, and the other isn't harmed.

The pure absurdity of an air-breathing bird getting into a shark's mouth and living there did not deter the man from believing his misunderstanding/misremembering. It did not deter the belief of the talk show host, who accepted that absurdity with awe for the wonders of nature. I am sure it did not deter the belief of many, many thousands of of listeners of that popular show, who then went on and repeated the wonderful thing they had just learned on the radio.

The topic of this thread is a heck of a lot more believable than that lunacy.

 

[JohnnyC]

In the similar vein as a bucket of steam or a sky hook, it's common to tell the new roadie that he needs to make sure he doesn't forget the cable stretcher before load out. Typically this results in a nervous roadie wandering all over the arena looking for something that he's never even seen before.

Cue smartass farm boy, walks out of the arena, grabs a cab and heads to the local farm store. Grabs a nice lunch, some coffee, generally wastes most of the day. Walks back inside and every grizzled stagehand is PISSED that he's been gone for hours.... "What the hell do you think you're doing?! Where the hell have you been?!" "Well, the LX crew chief told me to get the cable stretcher, and I'd never seen any in the road boxes, and he made it seem real important that I find one. So here ya go....." as smartass farm boy drops a fence cable stretcher onto the head LX's gak box. He didn't buy a beer for weeks.

 

[RainPilot]

"Go ask the bosuns mate for a long weight"

Air Force guys on ships really should just make life easier and paint a target on their flight suits.

 

[dmaziuk]

... as smartass farm boy drops a fence cable stretcher onto the head LX's gak box. He didn't buy a beer for weeks.

I suspect one could very carefully cool down steam so it stays in a bucket... or use something like dry ice perhaps, to achieve a similar result for "bucket of steam". Can't think of a way to make a bucket of compression, though, or a spool of water line.

 

[Aviyes]

"Go ask the bosuns mate for a long weight"

Air Force guys on ships really should just make life easier and paint a target on their flight suits.

Must not have been a maintainer. Otherwise, they would have already experienced the search for left-handed screwdrivers/wrench sets, headlight fluid, SIF paint, etc.

 

[RainPilot]

Must not have been a maintainer. Otherwise, they would have already experienced the search for left-handed screwdrivers/wrench sets, headlight fluid, SIF paint, etc.

Nope it was me and my crew spending some time on a frigate. All flying types, not useful types.

 

[Blasto]

I suspect one could very carefully cool down steam so it stays in a bucket... or use something like dry ice perhaps, to achieve a similar result for "bucket of steam".

Cooled down steam is water. What is known as "cold steam", and basically visible steam, is water mist. Real steam just expands and condenses quickly. About the only way to keep it in a bucket is to weight it down with negative bubbles.

 

[FinnMom]

Well let's see... a bubble is a nugget of air surrponded by water, so a negative bubble must be a nugget of water surrounded by air: a water droplet. So maybe he's telling you that if you fill your BCD with water at 40m, it won't float so great.

A negative bubble could also just be a manic-depressive bubble having a bad day.

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Please don't be offended by our having fun. Your friend may have been talking about many real and interesting things, he just didn't express himself well enough.