Fun With Science

[TreborS]

We can have a lot of fun with most of the fields of science as long as we don’t get carried away and take it too seriously. Most people do take it too seriously.

 

In many of the sciences, most of the advances are theoretical. Of course, if it’s your theory that gets made fun of, you could get a little bent out of shape. We could start with something in physics. Even that name can start me chuckling.

 

Let’s pick on gravity. It’s responsible for things like weight and m’ass. You’ve gotta laugh at something that is pronounced m’cu in French.

 

Now that we’ve selected a part of science, we should get to know what we’re talking about. To be absolutely frank, gravity sucks. It sucks because it is a natural force that attracts objects towards each other. The name was first applied to the force that attracts a body at the surface of the earth towards the center of the earth. For that name, we have to thank the French word which means heaviness. We should be glad that it is not pronounced m’gravity.

 

This force results in something we call weight. This name is not to be confuse with m’ass which is the same thing at the surface to the earth except that weight is expressed in pounds while m’ass is express in kilograms. At the surface to the earth, an object that has 2.2 lb of weight has 1 kilogram of mass. Yep, same thing. Away from the surface to the earth, things change. Weight varies and mass does not. Scientists do not consider this funny. I do. It’s funny because they are caused by the same thing. Gravity.

 

To repeat the schoolbook definition, mass is the quantity of matter in an object. It is the measurement of the inertia or sluggishness that object exhibits in response to any effort made to start it in motion, stop its motion, or change in any way its state of motion. Weight is the force on an object due to gravity.

 

To me, I visualize weight as being represent by a rubber band connection the object to the center of the earth with a tension equal to the weight of the object. This is the simplistic explanation. In reality, every atom of the object is gravitationally attracted by every atom of the earth and visa versa. Nature senses all of these attractions at once. The resultant is an apparent force that is centered at the exact center-of-mass of each of the objects. Instead of zillion upon zillions of rubber bands only one is effectively connected between the center of mass of both objects. This makes computations by men using the gravitational formula F= G M1 M2/D^2 simple indeed.. Nature does it constantly between all the associated atoms.

 

Your right, there is nothing here that we can consider funny HaHa or even funny peculiar.

 

If we move out and consider the solar system, we find that nature again has the upper hand. Nature computes F= G M1 M2/D^2 considering all the components at once. Man runs into a buzz saw here.

 

In astronomy, the problem of determining the motion of three or more celestial bodies

moving under no influence other than that of their mutual gravitation. No general solution of this

problem (or the more general problem involving more than three bodies) is possible. This statement comes right out of Encyclopedia Britanica.

 

The funny thing is that there really is no such thing as three, four or more body problem in nature. Nature deals with all multiple body situations as if there is only two bodies. In our solar system, the sun solves this problem by always sensing all the planets as if they were a single body centered at the center-of-mass of all these planets. The same is true for the earth. It is gravitationally aware only of the center-of-mass of the sun and all the other planets.

 

In fact, the solar system planets center-of-mass and the sun balance each other’s mass by revolving around a common point which is the center of mass of the solar system. The resultant solar system center-of-mass is not at the center of the sun but, rotates around the center of the sun in an eccentric orbit which follows the odd variations in the center-of -mass of the planets as they travel through their orbits. Large massive bodies like the sun do not like sudden changes. It cannot actually follow the eccentric rotational motions of the combined center of mass. It cheats and follows a much less eccentric rotation. This cheating does not go undetected by the planets. Their orbital distances and velocities are modified in such a way that the erratic motion of their center of gravity are lessened. Planetary orbits thus evolve over time to reduce this eccentricity. That is one reason why most planets revolve in the same direction. Think of the increased erratic behavior a counter-revolving planet would cause. The counter-revolving planet would eventually be made to behave. Another thing is that planetary orbital changes would make planetary conjunctions as infrequent as possible. Funny peculiar isn’t it?

 

Now, back to m’ass. All objects resist changes in their state of motion. All objects have this tendency - they have inertia. But do some objects have more of a tendency to resist changes than others? Absolutely yes! The tendency of an object to resist changes in its state of motion is dependent upon mass. Inertia is that quantity which is solely dependent upon mass. The more mass which an object has, the more inertia it has - the more tendency it has to resist changes in its state of motion. Now, why is that?

 

As we have previously mentioned, there seems to be a complementary gravitational attraction between all bodies in the universe. Of course, there is a greater force of attraction between close bodies as specified per F= G M1 M2/D^2. But, that does not mean that far away bodies are excluded. Again, there is no gravitational umbrella.. If we do our rubber band trick with all the universal objects, a body like the earth would be tied to every other body with all the rubber bands exerting a force on the earth from all directions. This omni-directional force would tend to hold the earth in a fixed position. It would resist any force tending to force it out of this location. It would seem to have an inertia. The value of this inertia would be dependent on the mass of the earth which in turn would be dependent on the value of mass of the rest of the universe. Another funny peculiar because, any change in the mass of the universe such as would be caused by an expanding universe (remember F= G M1 M2) would be reflected as a change in the mass of the earth.

 

That is enough hilarity for today.

[[Tycho?]]

I lost you at that last paragraph of yours, care to go into more detail on that?

[TreborS]

I’m not sure that I can explain that last paragraph to your satisfaction, but I’ll try. Here goes...

 

A gravitational force exists between every body in the universe. I just happened to select the earth as the body of interest. Any other body anyplace in universe would have suited just as well. All of these forces are omni-directional and they all pull at the earth. This omni-directional pulling attraction has the effect of holding the earth at a universal central point which provided the earth with an inertia. The magnitude of this force is in effect the matter/energy relationship of the earth to the rest of the universe and we call it m’ass. If this is true, this mass we call the earth has a fixed value which tells us a few things about our universe. Since the earth’s mass is finite, so is the universe’s mass. Since the earth’s mass is fixed, the mass of the universe is also fixed and is not expanding or contracting (remember F= G M1 M2). If the universe is infinite, then the fixed mass of the earth also tell us that the gravitational force has a fixed limit. I had not mentioned these inferences before because I though that they were implied and need not be expanded upon.

 

Seems that this explanatory paragraph is shorter than the original one. I might not have done a good enough job....................TraborS

[uncool]

The one problem with this is that it completely misunderstands how center of mass works. The attraction is neither directly between the center of masses, nor is it only related to that. This can easily be shown by using 2 objects of radius r at distance 2r. While the attraction between the center of masses is GM1M2/4r^2, at certain points the attraction is much, much greater, such as at the point of tangency.

 

This is the reason why the 3-body problem cannot be solved. Nature doesn't act as if it's a two-body problem - if it did, then the 3-body problem would be reducible to the 2-body problem and therefore be exactly solvable, which it is not. The argument entirely breaks down there.

=Uncool-

[TreborS]

In the real world, there is no such thing as a 3-body problem. Since there is no gravitational umbrella, there is only a 2-body problem: the subject body and the rest of the universe. Any subject body cannot react gravitationally with just another or two other bodies. It is constantly solving the 2-body problem between it’s own center-of-mass and the apparent center-of-mass of everything else. Nature just does it. Man tries to reduce it to a mathematical problem by isolating a few bodies from the n-bodies of the universe. ......TreborS

[[Tycho?]]

This omni-directional pulling attraction has the effect of holding the earth at a universal central point which provided the earth with an inertia.

 

How is the earth held at a central point? And how does this provide earth with an intertia?

 

 

 

The magnitude of this force is in effect the matter/energy relationship of the earth to the rest of the universe and we call it m’ass.

 

Mass does not have an apostraphe in it. How is the magnitude of the force the matter/energy relationship of the earth to the rest of the universe? What does matter/energy relationship mean? How does this mean mass?

 

 

While this is probably true, why does it follow from the previous statement?

 

If the universe is infinite, then the fixed mass of the earth also tell us that the gravitational force has a fixed limit.

 

Gravitational force has a fixed limit? What does this mean, what sort of limit?

[uncool]

In the real world, there is no such thing as a 3-body problem. Since there is no gravitational umbrella, there is only a 2-body problem: the subject body and the rest of the universe. Any subject body cannot react gravitationally with just another or two other bodies. It is constantly solving the 2-body problem between it’s own center-of-mass and the apparent center-of-mass of everything else. Nature just does it. Man tries to reduce it to a mathematical problem by isolating a few bodies from the n-bodies of the universe. ......TreborS

 

You are utterly and entirely wrong. The center of mass is used as an approximation - not as the actual event. If, say, there is a tiny object that is an extremely small distance away - such a small distance that it has the largest effect on the other object - then even though the center of mass hasn't changed much, the gravitational pull on the object has. The center of mass is not correct as is - it is simply an approximation.

 

If what you were saying were true, then the 3-body problem itself would reduce to a 2-body problem, and therefore be solvable - which it is not.

=Uncool-

[D H]

This thread is just Mach's Principle / Einstein's Equivalence Principle writ small with a bunch of errors.

 

In astronomy, the problem of determining the motion of three or more celestial bodies moving under no influence other than that of their mutual gravitation. No general solution of this problem (or the more general problem involving more than three bodies) is possible.

 

This statement is made so often and it is just plain wrong. People solve the N-body problem every day. How do you think we are able to send spacecraft to other planets? If the problem were insoluble, why would JPL have a web site like this http://ssd.jpl.nasa.gov/?ephemerides that is all about solving the N-body problem for our solar system?

 

From Marion, J.B., "Classical Dynamics of Particles and Systems: Second Edition", Academic Press, New York, 1970 (italics added):

The addition of a third body to the system, however in general renders the problem insoluble

in finite terms by means of any elementary function

.

 

Dropping the italicized words changes a true statement into a false statement. The problem is soluble, just not in terms of elementary functions.

 

K.F. Sundman showed that an integral power series representation in terms of the inverses of the cube roots of the radial distances must exist. The French Academy of Science awarded Sundman with the de Pontécoulant's Prize for his work in solving the N-body problem. A 1915 review of his work is here: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1915Obs....38..429.&data_type=PDF_HIGH&type=PRINTER&filetype=.pdf

 

The funny thing is that there really is no such thing as three, four or more body problem in nature. Nature deals with all multiple body situations as if there is only two bodies. In our solar system, the sun solves this problem by always sensing all the planets as if they were a single body centered at the center-of-mass of all these planets. The same is true for the earth. It is gravitationally aware only of the center-of-mass of the sun and all the other planets.

 

A simple counterexample: a free-floating object inside a hollow sphere experiences no gravitational acceleration due to the sphere.

 

 

Another funny peculiar because, any change in the mass of the universe such as would be caused by an expanding universe (remember F= G M1 M2) would be reflected as a change in the mass of the earth.

 

The expansion of the universe is all about the universe's physical extent, not its mass.

 

That is enough hilarity for today.

 

Agreed.

[TreborS]

Quote:How is the earth held at a central point? And how does this provide earth with an intertia?

 

Tycho, imagine a tug-ofwar between two absolutely equal team with each rope tied to a ring that we will use to represent our earth. We are simplifying the problem by using only two team instead of an n-number of teams. Since each team uses identical pulling forces, the ring cannot move. It can be said to have inertia. It is held stationary at one point with a total force that is could be interpreted as a mass.

 

Quote: Mass does not have an apostraphe in it. How is the magnitude of the force the matter/energy relationship of the earth to the rest of the universe? What does matter/energy relationship mean? How does this mean mass?

 

We know that mass does not have an apostrophe in it–I was using the apostrophe as a comical point. Returning to our tug-of-war. If we increase the amount of matter in the earth object, the tug-of-war has an increased amount of pulling teams. This increased n+ number of teams, which is solely due to the increased amount of matter in the earth object, now feels a much greater force. This increase in force represents increased mass which in turn is of a magnitude relationship to the amount of matter in the rest of the universe.

 

What we know as matter is really the sum of the matter in an object plus all it’s internal/external forces which is energy. This, the use of the term matter/enery.

 

Quote: Gravitational force has a fixed limit? What does this mean, what sort of limit?

 

This phrase is part of the statement (If the universe is infinite, then the fixed mass of the earth also tell us that the gravitational force has a fixed limit). This statement is a bit strong. It was meant to imply that the combination an infinite universe and a gravitational that was also unlimited would sort of provide us with an inertia value for the earth that would also be infinite. How many levels of infinities can exist? TreborS

[TreborS]

Dear Uncool, I could be utterly and entirely wrong. It wouldn’t be the first time in my 76 years. If I am wrong, it won’t be for a long period of time. Then, I will know and, if your were correct, I will bow to your excellent reasoning. I may even come back and pull your toes. Until then, I’ll keep smiling and smelling the roses along the way.............TreborS

[D H]

TreborS

Your argument has a basic flaw. You are using Newtonian gravity, in which the gravitational attraction to an object inside a spherical distribution of mass is zero. The universe appears to have a very even mass distribution. The net gravitational attraction of the rest of the universe on the Earth is essentially zero under Newtonian gravity. You have to go much more elaborate models of gravity to get something inertia out of gravity.

 

Which is exactly what Einstein did with general relativity.

[[Tycho?]]

Quote:How is the earth held at a central point? And how does this provide earth with an intertia?

 

Tycho, imagine a tug-ofwar between two absolutely equal team with each rope tied to a ring that we will use to represent our earth. We are simplifying the problem by using only two team instead of an n-number of teams. Since each team uses identical pulling forces, the ring cannot move. It can be said to have inertia. It is held stationary at one point with a total force that is could be interpreted as a mass.

 

Quote: Mass does not have an apostraphe in it. How is the magnitude of the force the matter/energy relationship of the earth to the rest of the universe? What does matter/energy relationship mean? How does this mean mass?

 

We know that mass does not have an apostrophe in it–I was using the apostrophe as a comical point. Returning to our tug-of-war. If we increase the amount of matter in the earth object, the tug-of-war has an increased amount of pulling teams. This increased n+ number of teams, which is solely due to the increased amount of matter in the earth object, now feels a much greater force. This increase in force represents increased mass which in turn is of a magnitude relationship to the amount of matter in the rest of the universe.

 

What we know as matter is really the sum of the matter in an object plus all it’s internal/external forces which is energy. This, the use of the term matter/enery.

 

Quote: Gravitational force has a fixed limit? What does this mean, what sort of limit?

 

This phrase is part of the statement (If the universe is infinite, then the fixed mass of the earth also tell us that the gravitational force has a fixed limit). This statement is a bit strong. It was meant to imply that the combination an infinite universe and a gravitational that was also unlimited would sort of provide us with an inertia value for the earth that would also be infinite. How many levels of infinities can exist? TreborS

 

 

I dont think you know what you are talking about. That first point, about the external forces being equivilant to inertia and mass, or something. Can you back this up numerically? A property of intertia is that an object resists change in motion, but just because something resists a change in motion certainly does not insure that it is intertia. You'll need some equations here to back you up.

 

I dont follow your analogy with these pulling teams, and increasing the matter/force on the earth, or whatever you are talking about. You'll need to make this explanation far more technical, or go straight to equations.

[uncool]

Dear Uncool, I could be utterly and entirely wrong. It wouldn’t be the first time in my 76 years. If I am wrong, it won’t be for a long period of time. Then, I will know and, if your were correct, I will bow to your excellent reasoning. I may even come back and pull your toes. Until then, I’ll keep smiling and smelling the roses along the way.............TreborS

 

...and this is all I get for my second post. Thank you very much for showing that you have no care for content, unless you will reply to my second post (and basically, my first post as well, since you completely ignored the point of that post, too).

=Uncool-

[TreborS]

My views of the universe and all of it’s quirks (and quarks) are the result of at least 70 of my 76 years of inputs into this little brain of mine. My bread-and-butter field was electronic engineering. When I wasn’t doing that, I was ingesting everything in the sciences, religion & even pseudo-sciences. For any calculations you need all the inputs you can get a hold of.

I have no conscious control of the outputs of these calculations. Not everything that was input was accepted. Too many humans are apt to swallow anything. For example, there are almost as many religions today as there are people. When you accept all, you end up by building the rest of your outputs on quicksand. My mind has a tendency to simplify instead of complicate things. It tends to generalize instead of specialize. There has been a lot of indigestible matter that has been left by the wayside.

I’m not saying that I’m correct in all the results that I have been writing about. But, honestly, they are the best I can do after all the filtering and reorganization that this little mind did. One cannot ask for much more.

It’s true what I stated at the beginning. Too many people have digested too much and will not be too pleased with having fun poked at their specialty. I’m also too old to keep up with all the responses. I print everything out and read at my leisure. The Texas desert air is good for old codgers and for their cogitations. No bugs like in Maine where I grew up.

I do not get riled at the negative or sometimes even insulting responses. I expected that when I started. In one of the forums, I was kept too busy trying to respond to all so that I never even got to finish my input thread.

I suggest that you sit back and think, think, think. Much of the information out there is set in shaky ground. Swallow some mental “Tums”. After you settle down, smile and smell the roses.

As for myself, I have many more threads to inflict on y’all.

[TreborS]

Please refer to Fun With Science #2 for further info on mathematics.

[swansont]

One cannot ask for much more.

 

One can ask that you post in "Speculations"

[D H]

One can ask that you post in "Speculations"

 

Especially since the only math in the OP is flawed.

 

TreborS: The entire underpinnings of the Gravity Recovery and Climate Experiment http://www.csr.utexas.edu/grace/ would be deeply flawed if gravitational attraction to a collection of objects could always be reduced to an acceleration to the center of mass of the objects.

[TreborS]

DH Quark: Got to look that one up.

[D H]

The gravitational force between two objects is a function of center of mass to center of mass only in the simplifying cases of point masses. The gravitational attraction on an orbiting spacecraft by the Earth varies as a satellite moves over mountains, oceans, etc. The Grace project measures these variations.

 

The primary products of the project are sets of spherical harmonic gravity coefficients, to a ridiculously high order. If gravity was center of mass to center of mass, only the zeroth order coefficient (i.e., the mass) would be needed.

 

An overview of Grace with a video is here: http://www.csr.utexas.edu/grace/gallery/animations/measurement/

 

From the video,

"Since the earth has varied features such as mountains, valleys, and underground caverns, the mass is not evenly distributed around the globe. The "lumps" observed in the Earth's gravitational field result from an uneven distribution of mass inside the Earth."