@bobdole Right. No lead can be in any consumer products, except if you live in China, North Korea, or Russia. So don’t ever worry
What is gravity? What is the effect of a solar eclipse?
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@Imperious:
Does any increase in barometric pressure have any effect on gravity? treat your answer as if we are dealing in a sealed room with all other things being equal.
The reason why i asked this was during my research i found estimates that the barometric pressure about 200-400 million years ago was about 3 times what it is today, while oxygen levels were at 35% (currently 21%). Of course there were major changes to oxygen levels during the 5 episodes of an asteroid hitting the earth and killing countless species.
I honestly do not believe that barometric pressure has an effect on gravity per se. Regardless of the barometric pressure of the Earth, moon, Saturn, Sun, etc. they will interact with each other based on their masses.
Now the relative effects on objects by an increased barometric pressure might have the effect of an increase in gravity as even air has mass, and an increase in barometric pressure would cause an increase in the mass of all air surrounding us - as the vast majority is above, it would have a crushing effect. Consider diving underwater. You have increased your surrounding “barometric pressure”. The reason your ears hurt is because this pressures your tympanic membranes inwards and the pain from the stretch receptors can only be mitigated by rising nearer the surface, or by equalizing the pressure by forcing air through your eustacian tubes by blowing against pursed lips and sealed nares.
Does this make any sense? F_alk? -
Baker, thanks for the info on the length of an eclipse.
@Imperious:
OK so what do you think as this as a possible explanation of why the larger animals died…
I think the most believable theory is the meteor impact.
And, i think you didn’t want to ask that, but that instead you wanted to ask:
“Why do you think was it possible at one stage in earth’s history that giant animals roamed the land but not today?”
(The the land is because of the Blue Whale (if it is not extinct yet) which was/is the larget animal ever AFAIR).i could have sworn that half of what F_alk said came directly from Stephen Hawkings’s “A Brief History of Time”
I don’t hope so. If so, then it didn’t happen on purpose (and i have to change my view on the book, as i didn’t like it that much).
Now the relative effects on objects by an increased barometric pressure might have the effect of an increase in gravity as even air has mass, and an increase in barometric pressure would cause an increase in the mass of all air surrounding us - as the vast majority is above, it would have a crushing effect. Consider diving underwater. You have increased your surrounding “barometric pressure”. The reason your ears hurt is because this pressures your tympanic membranes inwards and the pain from the stretch receptors can only be mitigated by rising nearer the surface, or by equalizing the pressure by forcing air through your eustacian tubes by blowing against pursed lips and sealed nares.
Hmmm … difficult.
To a degree this is certainly correct: We see what happens when he climb into high heights … and could then extrapolate to the case of higher densities.
I am not sure wether we can compare directly with the case of high pressure in water: water is a fluid after all, and fluid mechanics are different from gas mechanics.
A last thing, which is more related to the “large animals” question: higher surropunding pressure means more buoyancy, and thus less “weight” for the same mass. But, in gases the buoyancy is rather small (look at how big a zeppelin or ballon has to be to let rather small masses “float” in the air). And alone to double the pressure, we would need twice the number of atoms in the gas. This would still have no large effect on the buoyancy, which could have allowed giant growth.
So, i guess the effect that CC mentioned would be the most notable effect. If the pressure was vastly different, then we should see very strange physiology (correct word?) in the fossile records of that ages. -
Considering the atmosphere effectively ends about 100 miles above the earth (which is about 7,000) miles in diameter, and considering most gases condense to hundreths of their previous volume when frozen/solidified; even an atmosphere 10X denser than todays should produce an insiginificant change in gravity. Also, this thicker atmosphere (if it actually existed) is probably still locked inside the earth in some form or other.
As far as physiological changes, I would suspect you should see more streamlining (as in marine animals) since a denser atmosphere would make movement more difficult due to air resistance and make the effects of wind storms more severe. Smaller lungs might be a possibility due to an easier transfer of oxygen/CO2 due to the higher pressure. The effects on the tympanic membranes should be insignificant IMO because once you are stabilized at the higher/lower altitude or pressure all is well. The problems here are only with rapidly changing pressures.
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Smaller lungs might be a possibility due to an easier transfer of oxygen/CO2 due to the higher pressure.
Ok so oxygen transfer of a higher pressured world in LARGE animals is easier, while they have less ability to get air in a lower pressure?
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Ok so oxygen transfer of a higher pressured world in LARGE animals is easier, while they have less ability to get air in a lower pressure?
Well, a higher pressure (all else being equal) means there are more oxygen molecules in a given surface area. Therefore, for a given animal size, the lungs could potentially be smaller proportionally. It would not necessarily make life for large animals more possible because this might not be the limiting factor with regards to animal size.
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The September 95 issue of Discover magazine has an article on the fluctuations in the oxygen levels during the Carboniferous (p. 32). I don’t recall any literature being cited, but the 35% number was used as a reason for the huge insects of that period. The theory goes that as the concentration of oxygen increases so does the size of the animal that can be supported by diffusional oxygen transfer (also known as the squared/cubed law). This may help explain why they got so huge. So the question is rather why did they get large and secondly after the Asteroid hits every 150 million years, why dint they simply come back? IT the answer has to explain both land and sea animals, because after all the heat wave from a 100 megaton event would bake the Earth except for things burrowed in the ground or in the deep sea. (e.g. giant crabs and squids)
I am not trying to hyjack this thread, but i dont see a “good” answer for the demise of Dinasours only explained by Asteroids, because this event has occured at least 4 other times in earths history, based on geological records.
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To decrease oxygen content all you have to do is tie up the O2 into other substances, or reduce the conversion rate of other molecules to free O2.
So to decrease Oxygen levels you could:
1: reduce the amount of photosynthetic plant life (such as a die off caused by lack of sunshine due to high levels of dust in the air)
2: replace low repiratory rate animals (like reptiles) with high respiratory rate animals (like mammals)
3: have large volumes of oxidizable materials exposed to air (like a big chunk of Iron)Sounds like the asteroid theory does a good job of explaining the decrease in O2 levels to me.
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I am not debating the reason why the O2 level changed. I am trying to state the reason why the Dinasours died in both land and sea other than saying “a big rock” hit the earth so 100% were killed by that alone… or are their other factors?
- O2 levels didnt compensate for the ability of larger animals to breath
- Barometric Pressure and its effects of lungs for large animals.
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@Imperious:
I am not debating the reason why the O2 level changed. I am trying to state the reason why the Dinasours died in both land and sea other than saying “a big rock” hit the earth so 100% were killed by that alone… or are their other factors?
- O2 levels didnt compensate for the ability of larger animals to breath
- Barometric Pressure and its effects of lungs for large animals.
No but it played HAVOC with the food chain.
First you have reduced light from all the high atmospheric dust, that reduces the number of plants that can survive and plants form the foundation of the food chain, fewer plants, fewer animals. This is especially true of very big animals that need to take in either massive amounts of vegetable matter to survive, or that live on those animals that consume large amounts of vegetable matter. And don;t forget that Plankton is a plant, and is even more essential to the oceanic food chain than land-based plants. Plankton is also the producer of WAY more than half the O2 in the world.
Add in other effects, like Sulfur being released in to the atmosphere by the geological after effects of the impact, and you more than account for a huge die-off.
Also, don;t think that the other major impacts did not effect life like the dinosaur extinction event. We simply have a LOT more bones from this most recent event, and life was far more advanced into much larger creatures (thus effected more quickly) by this last massive impact.
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@F_alk:
i could have sworn that half of what F_alk said came directly from Stephen Hawkings’s “A Brief History of Time”
I don’t hope so. If so, then it didn’t happen on purpose (and i have to change my view on the book, as i didn’t like it that much).
i read the book again last night, well skimmed it is a better term (dont really feel like reading it again, i think we both kind of agree on its quality) while skimming through it i found similarites, but nothing to get my imaginary underwear in a bunch.
i will say i like the topic ,i have always liked gravity, here on earth it is basically the only constant.
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