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Not to be flippant, but unless you're planning to attend a science convention and need to have talking points about gravity, about the only things you need to know is:
1. Definition of...
2. Speed of...
3. Dependent on...
Not to be flippant, but unless you're planning to attend a science convention and need to have talking points about gravity, about the only things you need to know is:
1. Definition of...
2. Speed of...
3. Dependent on...
After that it's gobbledygook.
Well, I did focus a great deal of effort working with the subject matter; in both formulas and monitoring equipment.
Trying to take theory and apply it directly in the real world is often where you learn the most.
From our perspective, gravity seems pretty much the same in our everyday lives regardless of where you are on the planet. But when looking at it with greater precision, we find variations around the Earth, as others have mentioned. As Pitt mentioned, the strength of gravity depends on the mass of an object. Everything with mass has a gravitational pull.
The smallest bit of matter has its own a 'center' of gravity. By itself, it isn't very strong. But when you pack enormous quantities together, the gravity of the collective mass is stronger. So you where ever you are on the planet, the strength of gravity can vary. The variance can change because the planet is in constant motion, changing both externally and internally. The interior of the Earth sort of sloshes around, while the surface constantly pulls in bit of matter from space, which adds to the Earth's mass.
Looking at the big picture, the fundamental force of gravity might cause sort of grainy texture in warping space-time, in the sense that there are enormous numbers of bit of matter of all sizes with their gravitational fields mixing and blending, one way or another, with other gravitational fields. In a way, it's sort of like ripples in a pond. If you toss in a rock, the ripples of water expand outward. If you toss in several rocks, each one sends out ripples that eventually cross and blend with the other ripples.
With gravity it's just the reverse. Instead of expanding out from an object, it's pulling inward by each object. We end up with a hodgepodge of gravitational force coming from technically all objects throughout the universe. The farther away from an object, the weaker the effect of gravity becomes. But it doesn't necessarily dissipate to nothing. It just continues to grow weaker.
As human beings, each one of us also have our own gravitational pull. That reminds me of an episode of Family Guy...
2 questions.
1) Is there any way to measure or any natural indicators of what gravity was in the past? Similar to how we know the magnetic poles have shifted based on lava flows.
2) What types of events could cause gravity to change? and by how much? I am not geologist or physicist, but a few that seem probable to me are:
a) Shifting of the earths mass within the crust. Not sure how much this would change it if at all.
b) Shifting of the moon. It affects the oceans, why not the rest of the objects on earth.
c) A drastic change to earths density. While unlikely perhaps a large meteor with a large mass of dense material, similar to the concept of what killed the dinosaurs.
Here are the roots of my questions. What has always interested me about dinosaurs is their size. Why is it that nothing walking the earth even comes close now? Whales are close but they have the counter force of water pressure to support their mass. Same thing with plants. fossil records indicate that there were trees and plants that dwarf anything we have today. How is that possible? So my largely uneducated hypothesis is the gravity was less, allowing for the plants and animals to be larger in scale. Additionally that what ever event led to their demise was also coupled with a change in gravity. This lead to the evolution of smaller species, like mammals, to take over as the large species were no longer able to support their own weight. Just a wild theory. Please feel free to call me an idiot.
The events that lead to the extinction of the dinosaurs seem entirely consistent with an increase in radiation or other factors that created genetic mutations, and a bias towards animals that were small and had relatively short lifespans - with the possible exception of water dwellers. Large long-lived animals might receive a deadly dose of radiation or active chemical before reproductive age - killing them off in a generation - while smaller animals with shorter life cycles would survive, but with multiple genetic mutations, some of which would be viable, others not so much. As time went on and the radiation or other effect passed, the natural pressures of the advantage of being larger or more long-lived would tend to re-assert slowly. Modern horses are larger than ancient ones, etc.
Your question about gravity being a factor is fairly astute, but I think you just haven't carried the possibilities far enough. I suspect that the atmosphere of the earlier Earth may have been considerably denser or thicker, rather than gravity having been less due to smaller mass or other effects.
A denser atmosphere, perhaps lower in oxygen and higher in other heavier gasses and with more water vapor, would add a little support to large mass creatures, just as water supports whales, but more importantly could improve oxygenation of the tissues, similarly to how hyperbaric chambers work. An off-the-cuff consideration is that there would be limitations to the effect but that up to 50 psi might be entirely possible. Bones and supportive tissue can be pretty strong, so they aren't a as much of a limiting factor as you might think. Giraffes are perhaps a better example than elephants, given the stresses their necks undergo.
There are gravimetric maps of the Earth. Look around online and you'll find some. The variations in gravity are pretty small, percentagewise. The moon WAS closer to Earth once, but the time scales are all wrong for the effect you describe. Sudden inclusion of some supermass at the core, like a meteor of gold a few hundred miles in diameter, just aren't within the realm of possibility.
Brainstorming, passing through a MASSIVE interstellar dust cloud, could create gravity pulls that might act to counteract that of Earth, but the pulls from the cloud on one side of the Earth would cancel out the pull from the other side, so the net effect would be nil, except to have to be constantly dusting furniture.
I think atmospheric changes, and a mutagenic situation are much more likely the factors. Just MO.
Is the rate of gravity in Kansas the same as it is in Pakistan? Is it different at the equator than say in anartica? Is gravity the same in the marianas trench or on kilamanjaro?
Also has it always been constant over the millions of years? Is/has there been a trend?
Is there anyway to measure this other than taking emperical observations?
I have no idea but was pondering the question, forgive me I'm an international studies undergrad
Realistically, science cannot with 100% accuracy say that it always has been consistent. We have no reason to believe it hasn't been consistent, but then we don't really know.
Realistically, science cannot with 100% accuracy say that it always has been consistent. We have no reason to believe it hasn't been consistent, but then we don't really know.
Realistically, science cannot with 100% accuracy say that it always has been consistent. We have no reason to believe it hasn't been consistent, but then we don't really know.
And that demonstrates your appreciation of Science.
Quote:
Originally Posted by 6 Foot 3
Well were all waiting for your answers einstein.
Hey now... I might be merely a ghost but...
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