Just a simple Qustion

What causes gravity?

Thats it. Thats all I want to know. I remeber learning in school that it was caused by the rotation of the earth, but that logic fails with just a small knowage of physics. We are spinning at approx 1100mph centrifugal force would have thrown us off the planet long ago. I googled it and got nothing. How can we not know the answwer to this little question?

Hope this helps.

Gravitation is a natural phenomenon by which objects with mass attract one another.[1] In everyday life, gravitation is most commonly thought of as the agency which lends weight to objects with mass. Gravitation compels dispersed matter to coalesce, thus accounting for the existence of the Earth, the Sun, and most of the macroscopic objects in the universe. It is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth; for the formation of tides; for convection, by which fluid flow occurs under the influence of a temperature gradient and gravity; for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena observed on Earth. Modern physics describes gravitation using the general theory of relativity, in which gravitation is a consequence of the curvature of spacetime which governs the motion of inertial objects. The simpler Newton's law of universal gravitation provides an accurate approximation for most calculations.

The terms gravitation and gravity are mostly interchangeable in everyday use, but a distinction is made in scientific circles. "Gravitation" is a general term describing the phenomenon by which bodies with mass are attracted to one another, while "gravity" refers specifically to the net force exerted by the Earth on objects in its vicinity as well as by other factors, such as the Earth's rotation.[2][3]

Source

Also this on earth's gravity.

Earth's gravity
Main article: Earth's gravity
Every planetary body (including the Earth) is surrounded by its own gravitational field, which exerts an attractive force on all objects. Assuming a spherically symmetrical planet (a reasonable approximation), the strength of this field at any given point is proportional to the planetary body's mass and inversely proportional to the square of the distance from the center of the body.

The strength of the gravitational field is numerically equal to the acceleration of objects under its influence, and its value at the Earth's surface, denoted g, is approximately expressed below as the standard average.

g = 9.8 m/s2 = 32.2 ft/s2

This means that, ignoring air resistance, an object falling freely near the Earth's surface increases its velocity with 9.8 m/s (32.2 ft/s or 22 mph) for each second of its descent. Thus, an object starting from rest will attain a velocity of 9.8 m/s (32.2 ft/s) after one second, 19.6 m/s (64.4 ft/s) after two seconds, and so on, adding 9.8 m/s (32.2 ft/s) to each resulting velocity. Also, again ignoring air resistance, any and all objects, when dropped from the same height, will hit the ground at the same time.

According to Newton's 3rd Law, the Earth itself experiences an equal and opposite force to that acting on the falling object, meaning that the Earth also accelerates towards the object (until the object hits the earth, then the Law of Conservation of Energy states that it will move back with the same acceleration with which it initially moved forward, canceling out the two forces of gravity.). However, because the mass of the Earth is huge, the acceleration of the Earth by this same force is negligible, when measured relative to the system's center of mass.

Same source.

~Keeper

Originally posted by jmotley

I remeber learning in school that it was caused by the rotation of the earth...

Well, that school gets an 'F'!

I googled it and got nothing.

Odd. Here is a link for you. Should have lots of answers.

_____________________________________
Darn, ~Keeper~! You're fast!


[edit on 19 August 2009 by weedwhacker]

In my humble opinion.

Basically gravity is a word that man created to explain that all things with enormous amounts of mass, i.e., the Earth, have an attraction to things that are close by.

The bigger the mass, the stronger the pull. Hence, gravity.

I don't think anyone can explain how it happens. It just does. Scientists everywhere will say that theres laws for it. But:
I think there's more to it than an attraction. Its what holds everything in orbit, in galaxies, and star clusters. My thoughts: Its the power of God.

But I'll probably get flamed for that one.

reply to post by tothetenthpower


This is the definition of gravity. Not what causes it. I know what causes us to stay on the surface and things to fall. I want to know what causes gravity. Lets say the earth stopped spinning. would we all float off to space.

reply to post by jmotley


No, gravity is caused by the Mass of the particular object.

Take our Sun for example. It's the largest thing in our solar system, therefore, has the most gravitational pull and effects all planets in the same way.

Just like the moon is caught in Earth's gravity. It's because of the Earth's mass, it attracts large bodies towards it.

Planets are formed this way. Matter that constantly melds and strike into each other, eventually form a core, which upon being heavy enough, starts to attract other things around it to increase it's mass.

That's over millions of years however.

~Keeper

It is not a simple question at all! It is actually a very complicated Physical Chemistry / Physics question.

No proof of the mechanism of gravity exists, but it can be observed in the smallest particles known to man! It is some kind of intramolecular force that is diametric to the charged particles. It is most likely electrochemical on the micro/molecular scale, but on a macro scale I don't think there is any definitive answer!

Sounds like a life long PhD project! If you could ever define it, you may be able to find a "cure" for it!

Originally posted by jmotley

This is the definition of gravity. Not what causes it.

That's kinda sorta the point! Well, I guess you didn't read the whole link.

I know what causes us to stay on the surface and things to fall.

You do? Then, why ask?

Lets say the earth stopped spinning. would we all float off to space.

Oh, that's your question! Answer: NO.

Try reading, maybe this will help with answers.

Originally posted by getreadyalready
It is not a simple question at all! It is actually a very complicated Physical Chemistry / Physics question.
No proof of the mechanism of gravity exists, but it can be observed in the smallest particles known to man!

There you have it. No proof of the mechanism exists. But we believe in it, because we can see the effects of it on other objects. So we have a name for it.

Gravity. What causes it? We don't know!
Bigger things hold smaller things close by. Easy.

Truth is no one really knows what causes gravity but it seems to be the more mass the more gravity. There are probably hundreds of speculative theories and attempts to link it with other forces but none with any proof behind them all we really know are the effects we can see.

If anyone ever work's it out they will probably be as famous as Einstein.

Originally posted by Teknikal
If anyone ever work's it out they will probably be as famous as Einstein.

Pretty much. Mass interacting with spacetime? Somehow? I personally suspect it has something to do with the way mass "falls into itself" in several dimensions we can't quite comprehend. Maybe someday some super duper genius will figure it all out and be able to explain it to dopes like myself.

reply to post by jmotley

Gravity is caused by mass, the more mass you have the more
gravity you get.

Gravity

Pretty straight forward.

reply to post by weedwhacker


Love the link. (the first one gave me a 404 error) Thanks. It kinda answered my question but now I have many more. Really loved the part about if we turn off gravity then we turn off space time also

Originally posted by Ex_MislTech
reply to post by jmotley

 

Gravity is caused by mass, the more mass you have the more
gravity you get.

Gravity

Pretty straight forward.

That doesn't begin to explain "why" or "how". That is like saying to get rich, you need more money!

Why does one mass attract another mass? Why does more mass increase the attraction? Forget magnetics, they do not hold up. Forget motion (at least Macro motion). Energetics and vibrations are key to forming a foundation, but it doesn't go very far.

They are trick questions, there are no answers yet, but you get the idea. My favorite part of micro chemistry is that most things are empty space! The further you break down a particle, the more empty space you encounter! There is no such thing as a "solid" mass.

you should research Tesla and read ed Leedskanlin's book ,basically Tesla believed that gravity was a force pushing down on us not pulling us down and Leedskanlin well his stuff you have to read for yourself good luck, post what you find.

gravity is caused by the word of God himself. The atoms must obey him according to his rules. that is why things attract and repel. God spoke order into the universe and it obeys his command.

Originally posted by genius/idoit

....basically Tesla believed that gravity was a force pushing down on us not pulling us down...

Well, doesn't really matter what Tesla believed, does it?? If he couldn't show the science, and at least provide a coherent and testable theory, then he may as well have believed in Unicorns. His view would seem to have been far too narrow, as it didn't encompass the entirity of the Universe, and how gravity holds it all together.

There is still a lot to be discovered, hence that is why gravity is still referred to as theory. "Theory" doesn't mean guess, nor does it mean 'belief', it is an observable and repeatable scientific concept, very well understood to be a fact, it's just the final details left to be learned.

There is still a lot to understand about the sub-atomic scale, as well. The ultra-tiny and ultra-large tie together in ways that are just beginning to reveal. Mostly, via mathematics.

Gravity in layman's terms and imagination:

Gravity is caused by matter collecting together and squeezing space out. The space moves out, but continues to exert force back from all directions to the center of the mass.

As matter continues to collect due to magnetic attraction between atoms and "friction" created by some particle exchanges between very close atoms. Space is pushed outward. Similar to how you might imagine being submerged in very deep water where the water begins to exert force or pressure on you from all directions.

Imagine the water is space and a basket ball is the matter. When you pull the ball down it will get pressure from all sides. If you happen to be living on the ball you will feel this pressure and call it gravity. It will hold you on the ball and make you weigh something because your being pushed to the center of the ball.

Since you standing on that ball creates additional surface area for space to push on, your own mass contributes to the total pressure exerted on you and the ball.

Now you probably want to know what space is. Well we do not really know but it is obviously a form of energy that we do not yet know how to detect directly or measure. Its existence can be inferred by how light photons travel through space near massive objects.



A star on the other side of our sun may have multiple reflections if viewed from the other side of our sun. It is actually right dead center of the sun yet we see the light at many locations on the edges of the sun. This means the space is bent around the sun and the light travels around its edges. I think they call this Gravitation Lens

The light side of gravity

To understand how gravity and space interact, pretend you open hand in a pool of water is matter that is spread out in space. Now quickly squeeze your hand together and the water squirts out. Your closed hand no longer has water in it and your now rounded hand is feeling pressure from the water on all sides.

This thing we call space may be a result of a interactions of matter while moving through a vacuum (nothingness or void). As far as we know everything in the universe is moving.

So no one can yet define all the things that give us gravity but I tried to explain it as best I understand it. It exists because of the way everything else interacts. Lots more detailed and scientific info available with Google or bing searches.

Just for the record, the correct answer is NO ONE KNOWS, centrifugal/centripetal force is not gravitation. It probably has something to do with the strong and weak forces at the atomic level. The simple fact of the matter is that no one knows exactly why a smaller mass will be attracted to a larger mass in the vastness of space.
I havent actually seen an answer to your question yet.

[edit on 19-8-2009 by jameslewin]

reply to post by jameslewin


Technically, james, both bodies are attracted to each other. Inertia comes into play, though, and the actual motion of the larger mass towards the smaller is imperceptible, if there is a huge disparity in mass.

SO, gravity is really a very weak force, keep that in mind. Remember, magnetism will trump gravity, at least in the Earth's gravity gradient.

Of course, no one knows how magnetism works, either! AND electricty isn't fully understood. They are useful tools, but there is a lot to learn to realize their full potential.