Thread: i think the universal gravitational force formula is wrong:

an object is in orbit because both centrifugal force and force of gravity are in balance or are equal

gravitational formula stablishes that force of gravity varies with distance dividing by the distance squared, im gonna prove aplying conservation of momentum that centrifugal force varies with dividing the distance to the cube with which is imposible both are in balance if the radius varies as happens in ellipses

imagine a universe with such a gravitational constant that theres a sun and a planet orbiting each other and both weight 1 kg:

in the perihelium the planet has a speed of 2m/s and is at a distance of the sun of 1 m in the aphelium speed is 1 m/s and distance is 2 m

now lets apply the centrifugal force formula f=m*v*v/r
peri: Fc=1*2*2/1=4
aphe:Fc=1*1*1/2=0.5

so with a distance of 1 m theres a centrifugal force and therefore of gravity since the object is in orbit of 4N

and with a distance of 2 m theres a centrifugal force of 0.5N

so centrifugal force taking into acount conservation of momentum varies dividing by the radius elevated to 3

then how can gravity vary dividing by the radius squared while centrifugal force varies dividing by the distance to the cube

its imposible both balance as to make an orbit varying one dividing distance squared and the other distance to the cube

whats going on here?

in the perihelium the planet has a speed of 2m/s and is at a distance of the sun of 1 m in the aphelium speed is 1 m/s and distance is 2 m

If the sun and the planet are of equal mass, they would orbit a centre of mass at exactly the same distance.

all right:

imagine a satellite orbiting earth at 2 m/s at x m distance from earths center

when the satellite is at 2x m distance(this is called an eccentric orbit) conservation of momentum states its speed will be 1 m/s

now lets calculate centrifugal force in each case, the weight doesnt really matter so ill suppose the satellite weight is 1 kg so its easier

Fc=m*v*v/r

A: Fc=1*2*2/x=4/x

B:Fc=1*1*1/2x=0.5/x

so as you can see doubling the distance implies centrifugal force reduces 8 times

this means that centrifugal force for a satellite varies with the distance dividing by the distance elevated to 3,

(think that if doubling the distance force reduced 2 times, it would be divided by distance,if doubling distance force reduced 4 times it would be divided by distance sqaured , as doubling distance force reduces by 8 times it goes dividing by distance to the cube,if you double distance and force reduced 16 times distance would divide elevated to 4...)

but weve learnt that gravity varies with distance squared

then how can centrifugal force and gravitational force balance each other as the distance varies, (most orbits vary distance cause they make ellipses) dividing one by the distance squared and the other by the distance to the cube?

Originally Posted by luxtpm

an object is in orbit because both centrifugal force and force of gravity are in balance or are equal

This statement is actually wrong. The only orbit in which both always balance is the special case of a circular orbit, and perfectly circular orbits are an ideal that never exist in nature.

If you want to think of elliptical orbits in terms of gravity and centrifugal force it can be done this way.

Starting with the orbit at apo, its orbital velocity will be such that centrifugal force will be less than gravity. The object therefore falls inward. as it does so, its speed increases and centrifugal force goes up. Eventually it will reach a point where centrifugal force and gravity are equal. But at this point the object's momentum is still carrying it inward, it continues to fall. As it does so centrifugal force increases. Finally the braking effect of the centrifugal stops the fall inward. But by this point the centrifugal force is stronger than gravity, so the object starts climbing back out again. It passes the point where the two forces equal and overshoots it again, this time going outward. It doesn't stop its outward climb until it reaches the original apo distance again. It will have traveled a 360° circuit, will be moving at the same speed as it was when it started and ready to repeat the process all over again.

So there is nothing wrong with the gravitational force formula. In fact, the very reason that such orbits are possible is because it takes the form it does.

Originally Posted by luxtpm

an object is in orbit because both centrifugal force and force of gravity are in balance or are equal

gravitational formula stablishes that force of gravity varies with distance dividing by the distance squared, im gonna prove aplying conservation of momentum that centrifugal force varies with dividing the distance to the cube with which is imposible both are in balance if the radius varies as happens in ellipses

imagine a universe with such a gravitational constant that theres a sun and a planet orbiting each other and both weight 1 kg:

in the perihelium the planet has a speed of 2m/s and is at a distance of the sun of 1 m in the aphelium speed is 1 m/s and distance is 2 m

now lets apply the centrifugal force formula f=m*v*v/r
peri: Fc=1*2*2/1=4
aphe:Fc=1*1*1/2=0.5

so with a distance of 1 m theres a centrifugal force and therefore of gravity since the object is in orbit of 4N

and with a distance of 2 m theres a centrifugal force of 0.5N

so centrifugal force taking into acount conservation of momentum varies dividing by the radius elevated to 3

then how can gravity vary dividing by the radius squared while centrifugal force varies dividing by the distance to the cube

its imposible both balance as to make an orbit varying one dividing distance squared and the other distance to the cube

whats going on here?

Yah know, once upon a time there was a pretty bright guy who wondered why orbits did what they did and how Kepler's notions of planetary motion could be explained from more fundamental principles.

So, he put his mind to it and found that an inverse square law for gravity fit the bill precisely. It is because of the inverse square law that orbit do work, and that is what this guy found out.

Along the way he had to do a couple of things to help with the analysis. He needed differential equations, so he invented calculus.

The guy's name was Isaac Newton.

You would do well to go learn the physics and mathematica developed by Newton and abandon your nonsense.

A better way to explain orbits is to look at Newton's cannon:


Se the following image:



You have a very tall mountain, (300 km, much much taller than any real mountain) on which you have a mounted a level cannon. If you fire a cannon ball out of the cannon, it will travel forward and begin to fall, and it will follow a curved path to the ground. The higher the muzzle velocity, the less curved the path. So how far the ball travels before it hits the ground depends on the muzzle speed of the cannon. (as shown by the white lines indicating cannon balls shot at different velocities.)

Since the Earth is round, the ground curves out from under the ball as it travels. At a particular speed, the curve of the ball's path and the Earth's surface become concentric (they share the same center) and the Earth's surface curves out from under the ball just as much as it curve towards the Earth. The ball travels completely around the Earth returning to where it started and still traveling the same speed. If you had removed the cannon in the meantime(otherwise the ball will smack into the back of the cannon), it will just continue on repeating the loop endlessly. In essence, the ball [is] falling to Earth, it just keeps missing the Earth. This is an orbit.

Now the example shows a circular orbit, but it works for other orbits also. If the muzzle velocity is just slightly less, the ball still travel around the Earth, but will dip to a point a little below cannon altitude at a point 180° from the cannon. After which it will climb back up to cannon altitude. This is an orbit with an apogee at the cannon. If you increase the muzzle velocity, the ball will climb to a height greater than the cannon before falling back to cannon altitude. This is an orbit with the cannon at perigee.

If you continue to increase the muzzle velocity you will create orbits with higher and higher apogees. You can do this until you exceed a bit over 141% of the muzzle velocity needed for a circular orbit. After that the cannon ball will leave the Earth vicinity and not return as yuo have exceeded escape velocity.

So in these terms an orbit can be described as a free fall ballistic trajectory that always curves toward the Earth but never intersects it. Or put another way: An object in orbit is one falling towards Earth but continuously missing.

oh thanks a lot orbits always have intrigued me, i see wheres my mistake now

Originally Posted by DrRocket

Originally Posted by luxtpm

an object is in orbit because both centrifugal force and force of gravity are in balance or are equal

gravitational formula stablishes that force of gravity varies with distance dividing by the distance squared, im gonna prove aplying conservation of momentum that centrifugal force varies with dividing the distance to the cube with which is imposible both are in balance if the radius varies as happens in ellipses

imagine a universe with such a gravitational constant that theres a sun and a planet orbiting each other and both weight 1 kg:

in the perihelium the planet has a speed of 2m/s and is at a distance of the sun of 1 m in the aphelium speed is 1 m/s and distance is 2 m

now lets apply the centrifugal force formula f=m*v*v/r
peri: Fc=1*2*2/1=4
aphe:Fc=1*1*1/2=0.5

so with a distance of 1 m theres a centrifugal force and therefore of gravity since the object is in orbit of 4N

and with a distance of 2 m theres a centrifugal force of 0.5N

so centrifugal force taking into acount conservation of momentum varies dividing by the radius elevated to 3

then how can gravity vary dividing by the radius squared while centrifugal force varies dividing by the distance to the cube

its imposible both balance as to make an orbit varying one dividing distance squared and the other distance to the cube

whats going on here?

Yah know, once upon a time there was a pretty bright guy who wondered why orbits did what they did and how Kepler's notions of planetary motion could be explained from more fundamental principles.

So, he put his mind to it and found that an inverse square law for gravity fit the bill precisely. It is because of the inverse square law that orbit do work, and that is what this guy found out.

Along the way he had to do a couple of things to help with the analysis. He needed differential equations, so he invented calculus.

The guy's name was Isaac Newton.

You would do well to go learn the physics and mathematica developed by Newton and abandon your nonsense.

If Einstein had never published his theory of relativity in the 19th century and lived today in the 20th century and chose to publish his theories on this forum, you'd probably make a similar statement. While this poster is clearly mistaken in his thesis, at least it came as a learning opportunity and worked to keep cognitive activity high. Simply libeling this poster's beliefs does very little to convince them to change; this should have been realized in the thread on "Quadrature of Circles."

anyway i understand his point since i sounded quite bad saying i though newton was wrong, but i was just honest, really thought it, obviously it was my mistake

anyway does anybody know how newton managed to know that gravity decreases with the distance squared?

could he for example know mean distance and speed of every planet calcualte centrifugal force and from there obtaining force of gravity for every planet and then see how force varies with distance squared?

how did he do it?

Originally Posted by luxtpm

anyway i understand his point since i sounded quite bad saying i though newton was wrong, but i was just honest, really thought it, obviously it was my mistake

anyway does anybody know how newton managed to know that gravity decreases with the distance squared?

could he for example know mean distance and speed of every planet calcualte centrifugal force and from there obtaining force of gravity for every planet and then see how force varies with distance squared?

how did he do it?

The orbits of the planet's were well known at this time. Kepler had already discovered his three laws of planetary motion through sheer observation.

Newton was able to take those laws and show they were explained by gravity falling off by the square of the distance. As already noted, he invented a whole new branch of mathematics(calculus) to do so.

oh thanks a lot im anxious to start diferential calculus, next year

Originally Posted by luxtpm

anyway i understand his point since i sounded quite bad saying i though newton was wrong, but i was just honest, really thought it, obviously it was my mistake

anyway does anybody know how newton managed to know that gravity decreases with the distance squared?

could he for example know mean distance and speed of every planet calcualte centrifugal force and from there obtaining force of gravity for every planet and then see how force varies with distance squared?

how did he do it?

The inverse square law is consistent with elliptical orbits. It was known through Kepler that planetary orbits are elliptical (at least to a very good approximation).

A physical clue is this: Anything that is dependent on a "flux" or particles emanating from a point source or a spherically symmeterical source can be expected to obey an inverse square law. That is because the effect would be proportional to the density pasing through a unit area normal to the flux and because the area of a sphere grows like the square of distance ( and hence the flux density decays like .

Originally Posted by Ellatha

If Einstein had never published his theory of relativity in the 19th century and lived today in the 20th century and chose to publish his theories on this forum, you'd probably make a similar statement. While this poster is clearly mistaken in his thesis, at least it came as a learning opportunity and worked to keep cognitive activity high. Simply libeling this poster's beliefs does very little to convince them to change; this should have been realized in the thread on "Quadrature of Circles."

Nope. Einstein offered a real theory that is consistent with what is known to be true experimentally. It is consistent with Newtonian mechanics and gravity in the limit of velocities small with respect to the speed of light and with gravitational fields of low to moderate strength. That correspondence is very important. It is required in order to be consistent with experiment.

This guy has gotten over it, but whenever anyone starts out with " Newton (or Einstein or ....) is all wrong", rather than "I don't quite understand why .... " they go in the crank file. I have seen lots of them. Look around, there are quite a few around here. They seem to be nearly everywhere, compliments of the internet and they do a lot of damage to young people who don't know any better.

Einstein did not go around professing that Newton was completely out in left field. He in fact made good use of Newton's theory, recognized some problems, and developed a new theory that extends that of Newton. Newtonian mechanics is seen as a limiting case of Einstein's general relativity, not something that is wildly wrong. There is a BIG difference.

You can expect nutty claims and nuts to be clearly labeled. Questions will be answered, but wild claims will be trashed. There are way too many wackos who confuse innocent people reading this stuff to do otherwise.

The "Quadring the Circle" is a good example. There is no chance of convincing the OP of the truth of the matter. That is like arguing with a tree. But one can counter that sort of thing for the passive readers, which seems to have been done effectively based on reactions from late-comers.

It is not nearly so important to get people to change (it is a the minority who do) as it is to prevent the many real wackos from damaging younger lurkers (who I believe to be numerous), Those who can understand and change will likely do so in any case.

oh im sorry i was influenced by this:

http://www.youtube.com/watch?v=izE4_...eature=related

i think science is to be questioned not to be accepted as the bible thats why its science and not religion, not place for faith in science

i think george carlin is right, children should learn to question things, even newton

myself i question current science a lot and you know what, still havent found a flaw, yet i still question it to be sure its correct

Originally Posted by luxtpm

oh im sorry i was influenced by this:

http://www.youtube.com/watch?v=izE4_...eature=related

i think science is to be questioned not to be accepted as the bible thats why its science and not religion, not place for faith in science

i think george carlin is right, children should learn to question things, even newton

myself i question current science a lot and you know what, still havent found a flaw, yet i still question it to be sure its correct

Questioning is good. But you need to know what to question.

In science there are lots of things worth questioning. But those aspects that a re covered by accepted science are only susceptible to questioning under extreme circumstances.

So, Newtonian mechanics is known to be a very good approximation whenever speeds are low with respect to the speed of ligh and when gravity is low to moderate (say away from black holes and at macroscopic scales), all at macroscopic scales. There is no point in questioning it for most purposes.

But at very small scales you need quantum mechanics. And at very high speeds or in very high gravitatinal fields you need relativity, special or general.

We also know that there are problems with incompatibility between quantum mechanics and general relativity. Something needs to change. But that change cannot result in anything that strongly disagrees with either theory under circumstances in which they are known to be accurate.

So you need to learn how and what to question. Challenging everything is not productive. George Carlin had a point, but George Carlin is not a scientist. Scientific questioning must be more disciplined than social or political questioning.

There is no pont in questioning Newton, except in extreme circumstances. You are not dealing with extreme circumstances. Question George Carlin instead.

I disagree. I absolutely hate when people tell me to trust observed fact instead of explaining how it works.

Calculus and College Physics 1 should prove Newton to you, not the unknown or unheard of "experts" that sit in their mysterious, dark cave.

Originally Posted by DrRocket

Nope. Einstein offered a real theory that is consistent with what is known to be true experimentally.

Einstein's theories weren't proved until long after he published them. Essentially, what Einstein did was sit in his patent's office, think about a scenario that would imply speed at different velocities, and infer from that the basic principles of Relativity. This is little different from what the luxtpm did.

Originally Posted by DrRocket

It is consistent with Newtonian mechanics and gravity in the limit of velocities small with respect to the speed of light and with gravitational fields of low to moderate strength. That correspondence is very important. It is required in order to be consistent with experiment.

It isn't. In fact, Einstein would later go on to apologise to Newton. When Newton first published the Principia Mathematica, they would have (at least, appear to) failed, since eliminating friction completely would have been impossible. Another example of a defect in Newton was that he wasn't willing to consider the opinions of such intellects as Leibniz on the relative nature of space and mass(derived through the identity of indescernibles). When such others chose to question Newton's beliefs (Robert Hooke, as another example) Newton often attacked them, in some cases using sarcasim and as a result, most experts consider Newton highly hypersensitive and even possible depressed.

Originally Posted by DrRocket

Einstein did not go around professing that Newton was completely out in left field. He in fact made good use of Newton's theory, recognized some problems, and developed a new theory that extends that of Newton. Newtonian mechanics is seen as a limiting case of Einstein's general relativity, not something that is wildly wrong. There is a BIG difference.

Galileo Galilei did much of what you describe in your first sentence to the founders of the Aristotelianism method (namely, Aristotle). According the the physics developed by some of the ancient Greeks, objects are pulled to the Earth because they, "long to be with it." Another example of somebody who was attacked for his beliefs was a scientist that proposed the radical theory that the Earth revolves around the sun, his name was Nicolaus Copernicus and is recognised as among the greatest astronomers of the 15th century.

Originally Posted by DrRocket

You can expect nutty claims and nuts to be clearly labeled. Questions will be answered, but wild claims will be trashed. There are way too many wackos who confuse innocent people reading this stuff to do otherwise.

The "Quadring the Circle" is a good example. There is no chance of convincing the OP of the truth of the matter. That is like arguing with a tree. But one can counter that sort of thing for the passive readers, which seems to have been done effectively based on reactions from late-comers.

This is true.

Originally Posted by DrRocket

It is not nearly so important to get people to change (it is a the minority who do) as it is to prevent the many real wackos from damaging younger lurkers (who I believe to be numerous), Those who can understand and change will likely do so in any case.

If that is your contention, than I agree. You did on some occassions in the "Quadring the Circle" thread prove that the Clearwar was incorrect (simply by evaluating the formula and showing it's not compatible to the approximation of pi).

Originally Posted by Ellatha

Einstein's theories weren't proved until long after he published them. Essentially, what Einstein did was sit in his patent's office, think about a scenario that would imply speed at different velocities, and infer from that the basic principles of Relativity. This is little different from what the luxtpm did.

It is totally different from what the luxtpm did. And you don't have the story straight.

Einstein's special theory of relativity did not contradict Newtonian mechanics for velocities small with respect to that of light. In fact special relativity reduced to Newtonian mechanics in that case. The question of the "aether" had been an open problem in physics for some time prior to Einstein's theory, and Maxwell's theory of electrodynamics seemed to indicate no preference for any specific reference frame. Even though they seem to have had little influence on Einstein, the experiments of Michelson and Morely had cast great doubt on the exisence of the aether, and Eiinstein's theory explained those results neatly.

Einstein's general theory of relativity, which addresses gravity is also consistent with and reduce to Newtonian mechanics in the limit of velocities that are small with respect to the speed of light and gravitational fields that are moderate (outside of, for instance, black holes). It serves to unite special relativity with gravitational effects, and owes a great debt to Newton. That is wildly different from espousing that Newtonian gravity is fundamentally wrong, when is known to be very accurate under almost all ordinary conditions.

The orbits of satellites, planets, and spacecraft are all computed using ordinary Newtonian mechanics for most purposes. Only when extraordinary accuracy is needed is general relativity used.

Einstein, in his paper announcing general relativity in 1916, produced calculations closely matching the known precessin of the perihelion of Mercury,. That is is in fact instantaneous agreement with observation that was not available from Newtonian gravity. He also, in the same paper demonstrated that general relativity reduces to Newtonian mechanics in the relevant limits.

Einstein was neither an idle dreamer, nor a detractor of Newton.

Originally Posted by DrRocket

And you don't have the story straight.

How Einstein derived special relativity? I can provide several sources that disagree with you. Here is one:

"In 1905, Einstein is 26, a patent examiner, working on physics on his own. After hours, he creates the special theory of relativity, in which he demonstrates that measurements of time and distance vary systematically as anything moves relative to anything else. Which means that Newton was wrong. Space and time are not absolute, and the relativistic universe we inhabit is not the one Newton "discovered."

http://www.pbs.org/wgbh/nova/einstein/genius/

Not identical word for word, but I'd hardly say this is something of relevance.

Originally Posted by DrRocket

Einstein's special theory of relativity did not contradict Newtonian mechanics for velocities small with respect to that of light.

Yes, as relativity (with regard to time and velocity) begins to occur as velocity approaches the speed of light. Newton's theory is a general one, this can easily be seen in the context of his writing. Newton's general theory than only applies to certain (or "specialized") cases (velocities that aren't approaching the speed of light). He was incorrect from a general perspective, while still providing the world with a tremendous discovery and one of a massive scope of applications. This is long accepted by physcists and mathematicians alike, and a reason why Einstein is often considered a synonym for genius.

Originally Posted by DrRocket

In fact special relativity reduced to Newtonian mechanics in that case.

Reducing something that's supposed to be general is proving it incorrect. I could also say that . But, this conjecture only holds true for numbers equal to or greater than one; this would make me incorrect.

Originally Posted by DrRocket

The question of the "aether" had been an open problem in physics for some time prior to Einstein's theory, and Maxwell's theory of electrodynamics seemed to indicate no preference for any specific reference frame. Even though they seem to have had little influence on Einstein, the experiments of Michelson and Morely had cast great doubt on the exisence of the aether, and Eiinstein's theory explained those results neatly.

What exactly is "aether?"

Originally Posted by DrRocket

Einstein's general theory of relativity, which addresses gravity is also consistent with and reduce to Newtonian mechanics in the limit of velocities that are small with respect to the speed of light and gravitational fields that are moderate (outside of, for instance, black holes).

It doesn't. Einstein's theory puts limits on Newtonanian mechanics, and requires a different subject of study altogether to describe other scenarios. Newtonian mechanics was originally supposed to work for all speeds, Einstein's theory of relativity adjusted the system in this fashion: Newtonian mechanics = speeds that aren't approaching the speed of light, and Relativity = speeds that are approaching the speed of light. It takes something that's general and makes it more complicated.

Originally Posted by DrRocket

It serves to unite special relativity with gravitational effects, and owes a great debt to Newton. That is wildly different from espousing that Newtonian gravity is fundamentally wrong, when is known to be very accurate under almost all ordinary conditions.

This is true, and has not been questioned to date. Generally however, Isaac Newton was wrong. Why was Newton wrong? Because he made a general statement that wasn't general.

Originally Posted by DrRocket

The orbits of satellites, planets, and spacecraft are all computed using ordinary Newtonian mechanics for most purposes. Only when extraordinary accuracy is needed is general relativity used.

Yes. But being partially wrong and completely wrong still hold the fundamental noun; wrong.

Originally Posted by DrRocket

Einstein, in his paper announcing general relativity in 1916, produced calculations closely matching the known precessin of the perihelion of Mercury,. That is is in fact instantaneous agreement with observation that was not available from Newtonian gravity. He also, in the same paper demonstrated that general relativity reduces to Newtonian mechanics in the relevant limits.

Newton specified general laws, which turned out not to be general (worked in one of two cases, the one being that in which we live in). The best chance of proving that Newton wasn't wrong, but not right, is if Newton never mentioned his laws of motion under speeds that approach the speed of light. Unfortunately for Newton (and you), he did, as we know by the fact that he tried to set up expirements which prove that space and time were absolute. Furthermore, you don't seem to really agree with me that Einstein was correct and Newton wrong, but more so that Newton's statements were not completely wrong, and, in the most case, right. I don't disagree here either.

Originally Posted by DrRocket

Einstein was neither an idle dreamer, nor a detractor of Newton.

Newton was in some ways Einstein's hero, so he was certainly not a detractor of him (Newton).

Originally Posted by Ellatha

How Einstein derived special relativity? I can provide several sources that disagree with you. Here is one:

"In 1905, Einstein is 26, a patent examiner, working on physics on his own. After hours, he creates the special theory of relativity, in which he demonstrates that measurements of time and distance vary systematically as anything moves relative to anything else. Which means that Newton was wrong. Space and time are not absolute, and the relativistic universe we inhabit is not the one Newton "discovered."

http://www.pbs.org/wgbh/nova/einstein/genius/

Not identical word for word, but I'd hardly say this is something of relevance.

There are lots of Einstein myths out there. If you want a good biography try Einstein by Walter Isaacson. I really don't care what was on PBS, or any other TV show.

It doesn't matter that Newton's theory does not hold in complete generality. It is pretty certain that general relativity doesn't either. Ditto for quantum mechanics.

Physics advances as a series of successive approximations. None of the current theories are likely to be absolutely correct. That is just the way that it is.

That series of successive approximations entails a very important principle, the correspondence principle. The correspondence principle requires that new theories reduce to old theories within the domain of validity of the old theories. That is why when someone claims that Newton, or Einstein, or Heisenberg, or Feynman or ... is totally wrong you can be absolutely sure that the claim is bogus.