Gravity a "push" force?

[marked23]

...my first post here... so apologies if this was already covered.


I've long been wondering about gravity. It seems a little counterintuitive to me that gravity can be a pulling force.
Most of the forces we talk about in physics are "push" forces. A rocket, a piston, pulling on a lever ("pulling" on something is really pushing on it from the other side), pulling a chain are all examples of "push" forces. (challenge: name an example of a pulling force that is not ionic, gravity, or magnetic related)

"What's magnetism?" a question that still hasn't been answered. (at least not that I know of) Magnets clearly seem to be a pulling force. Anyone can easily demonstrate two magnets, placed near each other, leaping a short distance to join together. How does this happen? "One magnet sends an invisible rope of energy to the other magnet and reels it in." Or is it really something else... The ether between the magnets is cleansed (ordered) by their combined presense and thus a void between the magnets is created that causes the magnets themselves to fill the void...

Yes, I know all this talk about rockets, levers and magnets has nothing to do with Gravity, my intended topic... And reading back, my paragraph on magnets above is total bunk, but I'll keep it there because i hope it serves to describe why I think it's counterintuitive to have a pulling force.

Hypothesis:
Gravity is a pushing force.

Imagine the Earth and Moon being pushed together by something that exists in lesser quantity in the space between the Earth and the Moon than elsewhere in the universe. Smaller example: Imagine that the universe consists of two spheres (Earth and Moon stand-ins) and enough space to generously enclose both spheres. Also, at every point in space, there are tiny firemen spraying water in every direction at once. This water is special. It has the unbelievable ability to avoid collisions with itself or other water. (Light appears to act like this.)

So we've got these tiny firemen spraying water in every direction. What is the effect on these spheres? There are firemen all around. Even between the spheres. Because of the generously sized universe, there are far fewer firemen spraying water from between the two spheres than there are firemen spraying water from elsewhere.

The result is that there will be less "water pressure" between the two spheres than elsewhere. It's a short hop to the realization that these spheres will appear to be "pulled" together... When in fact they were actually pushed by the water.

My Problem: ...And your question
I don't know the calculus necessary to run this "two sphere" calculation, that's why I'm asking here. All things being equal, does the pressure difference in my explaination behave like gravity?

 

[jarsoffart]

a few jumbled thoughts with jumbled grammar:

Isn't gravity an attraction, it is part of the spheres, not part of the firemen. There will still be gravity even if there is nothing around the spheres, so the difference in pressure does not have anything to do with gravity. In response to the magnetism paragraph, magnets still work in a vaccuum, but there is nothing to be displaced and replaced. I sort of understand what you are thinking. You are thinking gravity is just the result of some medium (water/firemen) trying to equilibrate (make itself uniform?).

 

[Killbat]

Your model doesn't make any sense, if I'm reading you correctly.
Explain exactly why there is less "water pressure" between the spheres.

 

[Shalmanese]

For one thing, it violates Occam's razor. Your proposing a model with no empirical difference with the current model and is a good deal more complicated.

 

[Mday]

as far as i know, gravity is NOT a force.

gravity is a field. the field is imposed by matter on spacetime. the affect of this field on spacetime is an attractive force on other matter which also impose fields on spacetime creating other attractive forces. by attractive, i mean the direction of force is in the direction of the matter which is imposing the field.

the force falls off at the square of the distance between objects, so something TOO far away has no apparent force acting on the earth or the moon. and something closer with much less mass will be more affective.
--

and your question\thought experiment makes no sense.

electromagnetism is also a field.

 

[MAW1082]

(attractive force btwn 2 massive objects) = (G * m1 * m2) / (r^2)

G is a constant with a value of 6.6726E-11 m3 kg-1 s-2

And as for whether or not something is pulling or pushing, there is really no such thing. It all depends upon which reference fram you are looking at it from. For instance if we are in the reference frame of m1, m1 is stationary, but m2 is being pulled towards it. The same theory applies for m2.

If you are interested in learning mre about reference frames, I reccomend reading some of Einstein's theory of relativity, it will really bend your mind.

 

[sgtroyer]

Let me see if I can muddy things a bit.

Be very careful when you use intuition to draw physical conclusions. Physics makes no claim to being intuitive. Now, it seems like you're trying to describe the same thing in a different way. Rather than the earth and moon being pulled from the inside, they are pushed from the outside. Really, there is nothing wrong with describing this way: the net effect is the same. In fact, if I were to draw a free-body diagram, showing all of the forces on the two bodies, I would draw it exactly that way.

The more important distinction is between attractive and repulsive forces. Whether you think of it as pushing or pulling, gravity is always an attractive force. It will always pull things together, and never push them apart. The other common force, the electromagnetic force, can be either attractive or repulsive, depending on charge. (Side note, there are really only four physical forces: gravity, electromagnetic, strong, and weak. Everything can be classified as one of those. i.e. when I push down a key, the force really results from the electrostatic repulsion of the electrons in the atoms of my hand from the electrons in the atoms of the keyboard.)

You state that magnets are a pulling force, but really they can be both. Orient them north to south, and they pull together. Reverse one, and they push apart. As for what magnetism is, it is more or less understood, but complicated. And when I say it's understood, I mean by someone, not necessarily me. Your invisible rope explanation isn't far off. Particles stream from one body to the other transmitting the force. But now I'm getting into quantum electrodynamics, and if I'm not careful I'll stray into whether light is a wave or a particle, and everyone will get very worked up, so I'd better stop now.

 

[RossGr]

Physics is not about "Why" it is about creating a Mathmatical model which can be used to make meaningful predictions. We have several EXECELLENT models for gravitational forces the mathematical formulations are different, but the results are the same. As long as you come up with the correct predictions the actuall mechanism is not real important. We may NEVER know "why" or the actual mechanisms behind the universe as long as our models are useable and yield meaningful predictions they must be considered correct.

Where is the math behind your model? How do we use it? Does it correctly predict some phenomena more effeciently then the current models? If so then it may have some use. If not then...Why bother.

EDIT:
By the way, it is news to me that we do not understand magnetism.

Is your computer, like mine a electo-mechanical device? If we did not understand magnetism we would not be communicating in this way.

 

[sao123]

i believe the correct statement is....
Engineers say " we know what magnetism & gravity does, how to measure its effects, and reproduce and use them to our advantage."
Scientists say "What we need to figure out is why & how it does what it does..."

Which are you???

 

[RossGr]

Originally posted by: sao123
i believe the correct statement is....
Engineers say " we know what magnetism & gravity does, how to measure its effects, and reproduce and use them to our advantage."
Scientists say "What we need to figure out is why & how it does what it does..."

Which are you???

I assume this is addressed to me??

Good question, I am some where in the middle, not quite engineer and barely a scientist (This is my hobby!) IMHO the scientist works out the model, the engineer figures out how to apply it. Are our models a accurate representation of how the universe works or are then simply representations of what happens? As I said above, it is not clear that we will ever know. It is amazing how well we are able to model the universe with mathematics. The more you learn of how the models are created and how well they match the actual phenomena it is hard to believe anything other then the possibility that you are actually understanding how the universe works. This is the root of the belief that god is a mathematician.

But is this fact or little more then wishfull thinking? How can we KNOW?
We can't, and I doubt that we ever will. Even if we finally work out a GUT which ties it all into such a pretty little package that later generations will wonder why it took so long to figure it out something so trivial. Will it actually be a statement of how things work or will it simply be a model that given an input mimics an output.

 

[Shalmanese]

The thing is that Science by definition can never really figure out WHY something is happening. They can GUESS that when X happens, Y happens afterwards and there is a link between the two and they can say that Y happened because X happened but we can only ever infer stuff from observation.

 

[josphII]

first of all we DO know what magnetism is. magnetism is a force generating by the movement of electrons. why do electrical currents have this property? i guess we'd have to disect an electron to find that out.

and your model doesnt make much sense. you equate beams of light with water coming out of a hose, which quite simply doenst make any sense given the properties of photons are very much different thats the properties of water, ie they have no mass.

 

[josphII]

Originally posted by: Shalmanese
The thing is that Science by definition can never really figure out WHY something is happening. They can GUESS that when X happens, Y happens afterwards and there is a link between the two and they can say that Y happened because X happened but we can only ever infer stuff from observation.

simply not true

 

[Shalmanese]

josphII: Please clarify. Science can only ever observer phenomena and infer causal links. It can never provide reasons. For example, if you observed a billiard ball striking another one and the other one flying off, you could infer than the reason that the second ball moved was because the first one struck it. However, it could also be possible that billiard balls just move spontanteously on their own and that it was just a co-incidence that you happened to observe it in that sequence. Science is unable to tell you which of these two scenarios is true.

 

[Pudgygiant]

If you're gonna downplay "pulling" as "pushing from the other side", then why can't you just say gravity is "pushing from the other side"?

 

[RossGr]

Since gravity is a central force, that is one which acting towards the cm of a system it makes a lot more sense to imagine the force originate at the bodies and "pulling" them together. What is the source of your external push?

 

[DrPizza]

Actually, gravity is the least understood of the 4 fundamental forces. (and, it's the weakest of the forces)
Electromagnetic forces, by comparison, are very well understood. The force carrier for the electromagnetic force is the photon. The force carrier for gravitational force is the graviton, although gravitons have yet to be detected.

There's a Nobel prize for whoever figures out why mass attracts mass.

 

[Chaotic42]

Originally posted by: DrPizza
Actually, gravity is the least understood of the 4 fundamental forces. (and, it's the weakest of the forces)
Electromagnetic forces, by comparison, are very well understood. The force carrier for the electromagnetic force is the photon. The force carrier for gravitational force is the graviton, although gravitons have yet to be detected.

There's a Nobel prize for whoever figures out why mass attracts mass.

Give me a couple of decades. This is one of my dream goals.

 

[glugglug]

Originally posted by: marked23
...my first post here... so apologies if this was already covered.
I've long been wondering about gravity. It seems a little counterintuitive to me that gravity can be a pulling force.
Most of the forces we talk about in physics are "push" forces. A rocket, a piston, pulling on a lever ("pulling" on something is really pushing on it from the other side), pulling a chain are all examples of "push" forces. (challenge: name an example of a pulling force that is not ionic, gravity, or magnetic related)

Challenge: name an example of a force that is not related to electrical (ionic), gravitational, or magnetic (really a special case of electrical) fields. The force when you push against something that keeps pieces of matter from going through each other is just static-electrical repulsion from the negatively charged electrons orbiting each atom.

"What's magnetism?" a question that still hasn't been answered. (at least not that I know of) Magnets clearly seem to be a pulling force. Anyone can easily demonstrate two magnets, placed near each other, leaping a short distance to join together. How does this happen? "One magnet sends an invisible rope of energy to the other magnet and reels it in." Or is it really something else... The ether between the magnets is cleansed (ordered) by their combined presense and thus a void between the magnets is created that causes the magnets themselves to fill the void...

Magnetism is electrical currents interacting with each other. Sometimes this can be intuitively electrical currents, (an electromagnet created by piece of wire with current flowing through it wrapped around a metal bar for instance), or it can be that the electrons are flowing through a piece of metal in a given pattern more stably (typical magnet). Like static electrical forces, "magnetic" forces can also be attractive or repulsive. What happens is if you put two magnets next to each other in an orientation where the sides of each magnet closest to the the other repel each other, unless PERFECTLY balanced/evenly positioned, or otherwise restricted from spinning, the magnets will spin around so that sides attracted to each other are together.

 

[Hayabusa Rider]

Originally posted by: glugglug

Originally posted by: marked23
...my first post here... so apologies if this was already covered.
I've long been wondering about gravity. It seems a little counterintuitive to me that gravity can be a pulling force.
Most of the forces we talk about in physics are "push" forces. A rocket, a piston, pulling on a lever ("pulling" on something is really pushing on it from the other side), pulling a chain are all examples of "push" forces. (challenge: name an example of a pulling force that is not ionic, gravity, or magnetic related)

Challenge: name an example of a force that is not related to electrical (ionic), gravitational, or magnetic (really a special case of electrical) fields. The force when you push against something that keeps pieces of matter from going through each other is just static-electrical repulsion from the negatively charged electrons orbiting each atom.

"What's magnetism?" a question that still hasn't been answered. (at least not that I know of) Magnets clearly seem to be a pulling force. Anyone can easily demonstrate two magnets, placed near each other, leaping a short distance to join together. How does this happen? "One magnet sends an invisible rope of energy to the other magnet and reels it in." Or is it really something else... The ether between the magnets is cleansed (ordered) by their combined presense and thus a void between the magnets is created that causes the magnets themselves to fill the void...

Magnetism is electrical currents interacting with each other. Sometimes this can be intuitively electrical currents, (an electromagnet created by piece of wire with current flowing through it wrapped around a metal bar for instance), or it can be that the electrons are flowing through a piece of metal in a given pattern more stably (typical magnet). Like static electrical forces, "magnetic" forces can also be attractive or repulsive. What happens is if you put two magnets next to each other in an orientation where the sides of each magnet closest to the the other repel each other, unless PERFECTLY balanced/evenly positioned, or otherwise restricted from spinning, the magnets will spin around so that sides attracted to each other are together.

Well, that is how magnetism comes about, but not what it IS. The ultimate reality of these forces are unknown, and perhaps unknowable. It MAY be that humans are not smart enough to fully comprehend the natural universe. Doesn't hurt to keep trying though

 

[grant2]

Asking "why" is what seperates us from the lower animals.

Even a crow knows that if it drops rocks near an egg, it will eventually break.

A curious human figures out that it's the rock STRIKING the egg that breaks it, and completes the task much more efficiently.

 

[Hayabusa Rider]

Originally posted by: grant2
Asking "why" is what seperates us from the lower animals.

Even a crow knows that if it drops rocks near an egg, it will eventually break.

A curious human figures out that it's the rock STRIKING the egg that breaks it, and completes the task much more efficiently.

You have to be careful about what you mean by why. Why are we here? Why are we at all? Now many people would try to answer this with "how" The "why's" in this sense are unknowable though.

Why does a ball fall to the ground when dropped? I have no idea. I know what is responsible though. Yes, it is semantics, but the understanding of semantics is extremely important in communication.

 

[KRandor]

Hmmm.. Gravity... I've done some thinking about this before - but the local Physics Lecturer's didin't seem to 'get' my theory... (Or, more rather, didn't want to know).

The biggest problem with gravity, is that IT DOSEN'T FIT WITH WHAT WE 'KNOW' (or rather 'expect'...). The reason WHY, (in my opinion), is because it works at a much lower level than we have access to atm... So, why do I think that???

The biggest reason WHY I think gravity is far more 'advanced' than we think atm, is very simple: It's level of efficiency... Gravity is simply THE most efficient force we have ever encountered. However, because it IS so efficient, we can gain some insight into the way it works and effects objects etc...

The main things we know about gravity are:

It is a force generated by an object of mass that causes it to attract EVERY form of energy we know of/can measure in it's surrounding area - (It affects light, don't forget - which has no mass...) - in a HIGHLY CONSISTENT MANNER (I.e. the rate of acceleration is constant!). However, the rate at which it affects everything, depends on it's distance...

This can only happen if THE ENTIRE AREA SURROUNDING AN OBJECT WAS AFFECTED UNIFORMLY - and the reason why it is constant, is because what it's affecting in it's surrounding area is also constant. Area vs. Rate... The bigger the area, the slower the rate...

What we are dealing with here, at the most basic level, is Energy Transfer... And, because it seems to affect everything at a very basic level, I think that that is EXACTLY what it is doing... Which also means that the direction the objects affected by gravity move in, is also the direction of energy transfer... I.e. Gravity is caused by an object drawing in energy from it's surrounding area...

The questions, are why? - (Motion - probably - (all 'object's (particles etc) move a lot don't they?)) And what happens to the energy afterwards?

Well, thats my theory... I think the reason why we are getting no-where with gravity is that we are dealing with it at the wrong level... I don't think the 'graviton' actually exists... I think gravity is FAR simpler than that - (though it's cause might not be).

So, the only real questions I really want to see asked is WHY an object of mass needs to use energy (at a constant rate), and what happens to it (Though I think I might be close on the former).

Keill....

 

[Shalmanese]

KRandor: you sound like your dangerously close to proposing a perpetual motion machine. You've made a number of basic and fundamental errors in your assumptions.

 

[sao123]

I'm still not convinced that the universe at the elementary level isnt a perpetual motion machine, with 100% efficiency...

Why dont the 4 basic forces ever deplete and cease?
1)Strong & weak forces - atoms never run out of energy and collapse or fly apart.
2)Gravity - we have yet to figure out how to turn off gravity, or find matter that has run out of gravitational electricity.
3)Electromagnetic - every atom has a magnetic field (determined by the electron spin) which is never depleted(when all the fields of a particular group of atoms align, a magnet is created)

all these attractive and repulsive forces never deplete and must either be 100% efficient or not consume energy.
If this wasnt true...the laws of entropy and conservation of energy say the universe will eventually consume itself into nothingness. (that just aint gonna happen)