Epic overuse/misuse of words

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Originally Posted by holli4pirating

I would say... (the rest Dylan's long winded post here) ...

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In terms of physics you are probably right. Where the term comes from in the context of breathing mechanics is that relative to air pressure, the pressure in the chest is negative during inspiration. I suppose you can't truly have a negative pressure, but as Lee pointed out, it depends on the established zero point, which in this case is atmospheric pressure.
To be technically correct, I suppose it should be called "lower than atmospheric pressure breathing" but that doesn't sound as nice.

Lets see:
Negative pressure=Vacuum. When your diaphragm moves down and makes your lungs expand, it creates a vacuum that brings fresh air in.

My little annoyance is "Negative acceleration"

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Originally Posted by Mvcrash

Lets see:
Negative pressure=Vacuum. When your diaphragm moves down and makes your lungs expand, it creates a vacuum that brings fresh air in.

My little annoyance is "Negative acceleration"

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How do you define vacuum? From what you say, it appears your definition is "area of less pressure than elsewhere." It's not NEGATIVE (ERIC!), it's LESS than outside the lungs. When your diaphragm drops, there is still outward pressure on your lungs - if there wasn't they would collapse. If I was to extrapolate a negative pressure for lungs (not that there can be negative pressure)... it would be something which causes them to turn inside out.

What if you assume X acceleration is 0? Then any acceleration less than X would be negative. I'm kidding, obviously, but it's very similar to my negative pressure thing...

Hehe. I am participating in the hijacking of my own thread...

I think what mvcrash meant by vacuum is an area of lower pressure relative to the surrounding air. In that sense a vacuum is created. It's not a vacuum in terms of being totally void of anything.
I think part of the terminology just comes from a need to differentiate between "negative pressure breathing" (negative relative to the surrounding air) and "positive pressure ventilation" (positive relative to the surrounding air)
An interesting side note: the reason the lungs don't collapse because of the lower pressure is because air simultaneuosly enters to fill the "vacuum", thus the mechanics of inhalation. But... If we put a hole in the chest wall, air enters there as well and will lead to a collapsed lung, since the atmospheric pressure is higher than the internal pressure of the lung with each breath. (See pneumothorax and sucking chest wound)

Essentially we are arguing the same point, just a difference in semantics. Then again, that's what this thread is about!

If I have 20 razors and you have 10 razors, would I be correct to say that, compared to me you have:

a) less razors
b) negative razors
c) something else

Negative != less than

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Originally Posted by holli4pirating

How do you define vacuum? From what you say, it appears your definition is "area of less pressure than elsewhere." It's not NEGATIVE (ERIC!), it's LESS than outside the lungs. When your diaphragm drops, there is still outward pressure on your lungs - if there wasn't they would collapse. If I was to extrapolate a negative pressure for lungs (not that there can be negative pressure)... it would be something which causes them to turn inside out.

What if you assume X acceleration is 0? Then any acceleration less than X would be negative. I'm kidding, obviously, but it's very similar to my negative pressure thing...

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It sure is, that is why we AGREE!!!

I believe the use of 'negative' to mean 'less than' is a simplification of a scientific/engineering phrase 'negative ---- differential' - for example: 'negative pressure differential'.

It seems that over time the 'differential' has been dropped making the phrase nonsensical.

Of course this just means 'less than', but the whole point of writing a scientific paper is to make sure that no non-expert can read the paper, so we do anything we can to confuse casual readers. :)

Oh! and if you had 20 razors to my 10, I'd have fewer razors than you.

I'm certainly not arguing that the pressure in the chest is less than no pressure.
In this case, zero is set to higher than no pressure. ;)

It might be like if I went to a casino with $1000. If I gambled away $500, I would be $500 to the negative. In this example, 0 = $1000.

So, something positive can be negative, when zero isn't zero. :D

Quote:

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Originally Posted by holli4pirating

If I have 20 razors and you have 10 razors, would I be correct to say that, compared to me you have:

a) less razors
b) negative razors
c) something else

Negative != less than

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i do in-fact own fewer razors than you.

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Originally Posted by vthomlinson

i do in-fact own fewer razors than you.

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Superfluous hyphenation always gets my goat. :p