What is gravity? What is the effect of a solar eclipse?

[Guest]

Gravity is one of the 4 principal forces (the others are electromagnetic, weak and strong force). While the other three are based in quantum mechanics, and can be unified into one force (at energies high enough EM and weak turn into “electro-weak”, at even higher energies it is predicted that EW and strong become the same as well), Gravity is based on general relativity. It is one of the most important topics of physics to find the unifying theory for quantum mechanics and general relativity.

The essence of gravity is that masses bend the space. A bent space can be viewed as a force on other particles. This means: gravity is the attractive force between two masses. It has nothing at all to do with rotation. It has nothing to do with the barometric pressure. If in an otherwise closed/sealed room the pressure rises, then the temperature in that room will also rise. This is known as the “ideal gas law”.
(in reply to

Think about it, this post is about the spinning of the world!

in the now locked thread called:

Earth’s Gravity:…

and

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.

)

Solar eclipses are the shadow of the moon, blocking the sun’s light to reach the earth. I am not sure wether they ever last longer than 10 minutes at one spot. The effect on living beings is rather small. There is a small temperature drop for the time, and some animals act strangely during the eclipse. It does not change archeological, fossile or geological records. If you have ancient records of solar eclipses, they must be written by man. The effect of a few minutes without sun is just not visible in fossiles or geological data.
(in reply to

Astronomers trying to compare ancient solar eclipse records with their predictions found that they were off by a significant amount.

)

[Jermofoot]

Nobody told you?  Guess Germany’s education system is inferior to the U.S. Don’t they have, like, books and stuff over there?
During solar eclipses, flying lunar monkeys descend upon the Earth, and become a nuisance to the planet’s barometric pressure, rotational speed, and gravity - much like a gremlin to a WW2 bomber.  Unfortunately, it’s nearly impossible to clip their wings and put them in a zoo, so we’ll have to continue suffering under their oppressive rule.  I, for one, welcome our flying lunar monkey overlords!  I’m just glad they aren’t communists…

Back to being serious - I think some confusion can be attributed to the method of simulating gravity in an orbiting space station by rotating it on a central axis.  Not gravity, but the perception could be the same, I guess (can’t say I’ve been in an orbiting space station).

[221B Baker Street]

I am not sure wether they ever last longer than 10 minutes at one spot.

http://www.krysstal.com/ecintro.html

From the article:
The maximum duration of Totality is 7m 31s. Eclipses over seven minutes long are rare; only three occurred during the 20th Century and none are expected in the 21st Century.

[Imperious Leader]

OK so what do you think as this as a possible explanation of why the larger animals died…

I guess its time to revise my claim regarding any gravity changes, but i still remember this idea discussed at length in class many years ago. I did find this offered as a better appreciation of what may have happened:

reprinted from this site-

[/http://www.equalparenting-bc.ca/members/planet_earth.htm

Why Were The Animals and Plants Larger During The Jurassic Age?

Fossil records indicate that the animals and plants, throughout the world, grew to record sizes for a period of time on this earth. This worldwide discovery of enlarged species cannot all be explained by genetic factors. Scientists, led by Dr. Carl Baugh Ph.D. from Glen Rose, Texas, researched the fossil records of plants, animals, and birds. They came to the conclusion that the Jurassic atmospheric had to contain more oxygen and more carbon dioxide with higher pressure than the present atmosphere (14.7psi.). Addition research at the University of Tokyo with tomato plants indicated that the higher pressure with more carbon dioxide stimulated growth factors in plants. Dr. Carl Baugh developed an academic model of this pre-flood Jurassic atmosphere. He believes that the atmospheric pressure was about 28psi absolute.  His academic model calls for about 23% oxygen and ten times more carbon dioxide (3/10 of 1%). His research group has built the world’s first hyperbaric biosphere.

Fascinated with these discoveries, in the early 90’s I began studies into plant growth processes. This led to my personal discovery of plant enzyme functions and pH modifiers. By the mid 90’s I had built a research greenhouse to experiment with the Jurassic plant growth hypothesizes. Meanwhile, research in the Glen Rose hyperbaric biosphere continued to produce some amazing discoveries with snakes and insects. I also came across hyperbaric oxygen research in Russia that claimed some exciting healing benefits from high-pressure chambers with pure oxygen. In 1995 I turned most of my efforts towards developing a hyperbaric oxygen chamber for people, which would be based upon this Jurassic academic atmospheric model. My chamber was designed to operate at 28 psi absolute range (13 psi gauge pressure). I used air/oxygen concentrators to produce medical grade oxygen for breathing through nasal cannulas. This new design criteria and improved mechanical features proved to be lower cost to build and operate. Doctors began sending people to my research chamber to see what effects pressurized, oxygen-enriched air had on them. Although my research and results were not extensive, I was impressed with the safety and potential use of low-pressure air mixed hyperbaric oxygen chambers.

The conventional hyperbaric oxygen chambers use much higher pressures with 100% pure oxygen to treat a wide range of medical conditions. There is over 40 years worth of worldwide research in this field and in many cases the results are very good but limited. The high-pressure use of 100% pure oxygen increased oxygen toxicity and reduced the treatment times. Even so, the conventional chambers demonstrated accelerated growth and repair processes while improving the immune system’s functions. The biggest reason for the lack of available chambers has been the high cost to buy and operate these chambers.

Finally back to the point of this brief, why were the animals and plants so large? Scientists and medical researchers have found that the enzymes, in both animals and people, build and repair their own cells, tissue, and organ parts. Plants also have enzymes involved in the repair and building processes. Enzymes are called into action by growth and repair hormones. The past hyperbaric oxygen research has demonstrated the fact that the cell and tissue regeneration speeds up while at higher oxygen and pressure. I concluded that the enzymes are moving faster during those growth or repair hormone periods. I assumed that more available oxygen allows the enzymes to work faster. This would help explain why the animals and plants grew larger during the Jurassic age. Plants also rely on carbon dioxide (CO2) for their growth processes. The Jurassic studies indicated ten times as much CO2 at almost double the atmospheric pressure. The plants would have also absorbed more carbon dioxide, which through photosynthesis produced more sugar solution for the roots, thus stimulating faster plant growth. I think this research has potential long-term benefits for mankind. I hope more scientists get involved with the necessary funding to carry on.

[Imperious Leader]

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.

[Staff Sgt. Barnes]

i could have sworn that half of what F_alk said came directly from Stephen Hawkings’s “A Brief History of Time”

[cystic crypt]

@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?

[Guest]

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.

[221B Baker Street]

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.

[Imperious Leader]

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?

[221B Baker Street]

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.

[Imperious Leader]

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.

[Guest]

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.

[Imperious Leader]

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?

1. O2 levels didnt compensate for the ability of larger animals to breath
2. Barometric Pressure and its effects of lungs for large animals.

[Guest]

@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?

1. O2 levels didnt compensate for the ability of larger animals to breath
2. 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.

[Staff Sgt. Barnes]

@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.