MrDarwin

I agree, but for a different reason. I belive the size (small) and position (fetal) of the fetus are what make gravity irrelevant, not the buoyancy or pressure of the amniotic fluid.

As I said above, I will grant John one thing: I think the effects of buoyancy and pressure from the surrounding amniotic fluid are negligible, and discussions of such are taking this discussion on a tangent.

That said, I believe the effects of gravity are also negligible, and John still has not demonstrated why they are significant. As Rufus points out, John's diagram is referring to adult circulation, not fetal. Until John can give us more compelling evidence that gravity is significant to fetal circulation, and why gravity would play a significant role in making my proposed redesign of the fetal circulatory system less optimal than the original design, then everything else he says is completely irrelevant.

[ November 10, 2002: Message edited by: MrDarwin ]</p>

scigirl

Well I disagree - I think a lot of people are learning a lot about science (and about the difficulty in defending intelligent design) from these exchanges from Vanderzyden.

Not only that, but his silence in the other threads (one of which he started) speaks volumes.

I absolutely agree. I'm still feeling sorry for those poor giraffes, which are all going to die if you believe Vanderzyden's calculations.

scigirl

pz

Even if they weren't, there are no grounds for banning the guy. Being unresponsive, uninformed, and uneducable are not bannable crimes, I don't think. In a lot of ways, Vanderzyden has been a model poster, in the same way that a turnip would be, if it could type.
Not just giraffes--until now, I had no idea cow-tipping was a lethal sport, and I'm going to have to be more careful when picking up mice so that I don't rotate them.

Non-praying Mantis

Sorry to butt in and pick a nit, but it is best when thinking of pounds per square inch to think of division, not multiplication. If we break down the term into units we have:

PSI = pounds per square inch = lb / in^2

Just like 1 mile per hour is 1 mile / 1 hour.

Asha'man multiplied the surface area of his abs to get the total force exerted, not pressure:

74.5 psi = 74.5 lb / 1 in^2 is equivalent to 3,725 lb / 50 in^2

(sorry if the numbers are not exactly the same, I am going from memory)

Still, 15 pounds of pressure in a swimming pool is an inaccurate statement.

Oh, and Vanderzyden, why can't you just admit that your calculations are wrong? We wouldn't think any less of you if you did (that's not saying much, but anyway...), in fact, we might think more of you (probably a very little more, but still more...). At least you would appear to be honest about this particular problem.

Remember, if I say that 2+2 = 5, and somebody shows me that it is wrong, I shouldn't keep saying that 2+2=5, unless I was trying to delude myself. Just my humble opinion.

NPM

Dr Rick

I feel sorry for his wife; if she gets pregnant, John might not let her lie down for 9 months.

John's posts serve a purpose in that they show how uneducated and closed-minded an IDer must be to maintain his untenable beliefs.

Rick

[ November 10, 2002: Message edited by: rbochnermd ]</p>

Happy Wonderer

Fair enough; I was trying to state the principle in the most simple way possible. I figured that talking about division and then multiplying might be a little too confusing...

The statement from the article:

would probably be better as

(pressure doesn't exert pressure, so as written it is a non-sequitor) and I think even that is imprecise, but adequate for conveying the intent for the intended audience.

My point is that John was taking the first statement to read "15 PSI", looking up in a table that 15 PSI is at a depth of about 30 feet, and ridiculing the statement. Showing a complete incomprehension of the effects described.

Usually one reads for understanding. When someone makes a claim that seems absurd, our reaction depends upon how we view them. If we trust them, we assume that our interpretation of the words is incorrect and put some work into figuring out why we are misunderstanding them. If we think they are an idiot, then we turn our minds off.

What John is doing is reading for misunderstanding, assuming that everybody else in the world is an idiot. It will take him a few years (maybe until he graduates from high school) that such behavior eventually makes him look like an idiot. (I was there once...)

HW

Vibr8gKiwi

MrD said "I will grant John one thing: I think the effects of buoyancy and pressure from the surrounding amniotic fluid are negligible, and discussions of such are taking this discussion on a tangent."

I really don't know anything about this, however once the fetus gets large enough that the amniotic fluid doesn't matter, what about the rest of the mother's womb? Since humans are mostly water doesn't the mother’s womb in general act like one of those gravity suits jet pilots wear? I don't see the point in focusing on just the amniotic water (unless you're Van and trying to distract the issue).

Coragyps

A tenth-of-a-millimeter skin of water is more than plenty to do all the hydrostatic pressure communication any of us ever needed in utero. I'll bet you're correct in thinking that the rest of the abdominal cage does a lot of supporting, too, but as far as pressure transmission goes, a tablespoon of fluid would be enough, inside a suitably elastic container.

Jack the Bodiless

Vander:

There is NO AIR inside the uterus. It's a bag which contains nothing but fluids and solids. Gravity is utterly irrelevant unless the fetus is lying unsupported IN AIR on the floor of the uterus. The watery amniotic fluid, because it completely surrounds the fetus and fills the whole of the available space in the uterus, will counteract gravity at EVERY POINT in the system.

You have almost gotten it several times already. Pressure increases with depth at the SAME RATE inside and outside the fetus. The amount of fluid is irrelevant: the pressure is dependent ONLY on the depth below the surface.

And it doesn't matter how "tough" the fetal skin is: it is flexible, and will therefore transmit pressure to the tissues beneath.

Without the pressures generated by the heart, the difference in pressure between the interior and the exterior of the fetus, and the difference in pressure between the interior and exterior of EVERY blood vessel within the fetus, is ZERO.

And, while I haven't dived as deep as Asha'man has, I've frequently experienced two atmospheres of pressure (three overall, counting surface pressure). The notion that the ribcage is designed to resist even atmospheric pressure (fifteen pounds per square inch) is laughable. A typical person has considerably more than three thousand square inches of skin (ballpark figure: a 6-foot by 2-foot rectangle has 6x2x12x12=1728 square inches of area on each side). At the surface, my mighty frame withstands in excess of 45,000 pounds of crushing pressure: twenty meters under water, that goes up to 135,000 pounds.

Vander, no amount of "regrouping" will save you. Nor will any number of diagrams showing pipes bulging IN AIR because they lack the protection of the surrounding pressure.

You are STILL wrong.

Jack the Bodiless

...Hmmm.

Ordinarily I try to understand the other guy's position in an argument, especially where a misunderstanding of scientific principles is occurring.

However, in this case it appears that I am dealing, not with a mere failure to apply accepted scientific principles correctly, but with a profound case of hallucinatory insanity.

Vanderzyden: I, and others, have refuted your false claims regarding the effects of gravity on fetal blood circulation. We have done so repeatedly, using various analogies and illustrations of the principles involved.

...And yet you cannot "discern" any of the refutations?

I suspect that part of the problem here is that you do not know what a "refutation" actually is. Maybe everything is true unless the Bible says otherwise?

Consider the following hypothetical conversation:
Do you discern that this is a refutation, Vander?

How about:
This is slightly tougher, because it refers to outside historical knowledge. But do you doubt that it is a refutation?

Or do you just see blank spaces in this post? Are you literally incapable of discerning refutations?