Neutrinos back into the picture?

[ArmoSkater87]

100% vacuum would make both objects just sit in space. If you drop a hammer and a feather in a 100% vacuum they would just sit there. PUSH OR PULL THEORY THEY WOULD SIT THERE. Pull theory, there is nothing to attract the objects to accelerate them towards another objects center. Push theory, there is an equillibrium of particles hitting it from all sides keeping it in the same place.

OMG...100% vacuum doesn't mean in the vacuum of space. What i ment by that is if the Earth had no air or armosphere, or if the experiment would have been done in a chamber from which all the air had been vaccumed out. It doesn't even have to be 100%...it actually can't on earth, but it can get very close...around 99.99% I am guessing. I though you would understand why i said "asuming 100% vacuum"...i though you're smart enough to realize that i said that in order to tell you that it only works when only gravity is applying a force on the objects. Air causes friction force on them too, so do u see why i said 100% vacuum? I DIDNT mean in the vacuum of space, i ment ON earth, or the moon, or mars...whatever...u choose.

 

[urtalkinstupid]

Air causes friction forces because it "pushes" the objects. Eliminate air and there is no friction force. Now, you have a chamber where there is no air at all. Place the hammer and feather 3m above ground. Drop them at the same time. What happens? I don't think they fall at the same rate. I think they would fall faster in respect to their original acceleration. If they objects are being pulled towards the Earth center within this vaccum, they are being pulled depending on their weight. They have no air resistance, ergo they fall faster. They do not fall at the same time. Push model would make them fall slower and closer to the same rate. Less particles are in the air, allowing them to absorb less, making them fall slower.

Can anyone answer my question gravity with an ellaborate definition? Seems that you are avoiding my questions as well.

What is the distinct characteristic of matter that makes one object attract to another?

 

[chroot]

I don't think they fall at the same rate.

Why don't you do an experiment? It doesn't require much in the way of apparatus to show this to be false. All objects fall with the same acceleration in a vacuum. This very demonstration is shown yearly to thousands of freshmen at universities around the word... but wait, you haven't even completed high school yet.

I think they would fall faster in respect to their original acceleration. If they objects are being pulled towards the Earth center within this vaccum, they are being pulled depending on their weight.

You are correct that the force exerted a body falling in a gravitational field depends on its weight. As you can see by the equation

F = G\frac{M m_g}{r^2}

the force on the object is proportional to m_g, it's "gravitational mass."

On the other hand, the acceleration of an object is also dependent on its mass, as you can see from the equation

F = m_i a

where m_i is the "inertial mass."

If m_g and m_i were different, two bodies of different masses would not fall with the same acceleration. You do experiments to determine whether or not these masses are the same, and indeed experiments have been done even up into the last decade to verify that they are in fact the same. They can be shown to be the same to a few parts per trillion IIRC, which is as close as you can get to "identical" in experiment.

Now, assuming m_g = m_i = m, you can combine the two equations:

G\frac{M m}{r^2} = m a

G\frac{M}{r^2} = a

You can see that the acceleration of a body does not depend on its mass (or therefore density, which is mass per unit volume) at all. A feather and a hammer fall with the same acceleration. This is what the "pull theory" predicts, and this is what is observed in experiment.

Your push theory, on the other hand, predicts that denser bodies fall faster, and this is not what is observed. Your theory is incorrect, and glaringly so.

What is the distinct characteristic of matter that makes one object attract to another?

Mass (and energy) curve space, and free-falling masses move along geodesics (the straightest possible paths) in such curved space.

- Warren

 

[urtalkinstupid]

I'll perform your experiment.

Mass (and energy) curve space, and free-falling masses move along geodesics (the straightest possible paths) in such curved space.

That's not what I was looking. What makes the masses attract? I'm referring to Newton's pull theory not Einstein's space-time curvature.

 

[chroot]

That's not what I was looking. What makes the masses attract? I'm referring to Newton's pull theory not Einstein's space-time curvature.

Newton's theory is demonstrably wrong. Who cares what it said?

- Warren

 

[Entropy]

Can anyone answer my question gravity with an ellaborate definition? Seems that you are avoiding my questions as well.

What? I'm sorry but I can't answer fragmented sentences.

 

[urtalkinstupid]

What property of mass and energy curve space? If Newton's equations are so wrong, why are you giving me an experiment going by his theory?

This space-time curvature is still a mutual attraction through two objects. One massive object curves space, the other near by object goes down the incline. An attraction is made through space-time curvature. There is no such thing as space-time curvature.

Einstein was so dissatisfied with our lack of understanding
about gravity even two centuries after Newton that he invented
an entirely new theory of gravity as a warping of "four-
dimensional space-time" known as General Relativity Theory.
But this theory is even more mysterious and unexplained, and
also suffers from the same problems as Newton's gravitational
force theory. What is "four-dimensional space-time" and why
would the mere presence of matter warp it? Can this explain
the weight of objects in our hands or the energy expended by
gravity as it drives the dynamics of the universe? Where is the
apparently unlimited power source for it all?

 

[chroot]

What property of mass and energy curve space? If Newton's equations are so wrong, why are you giving me an experiment going by his theory?

Because you presumably wouldn't understand the same explanation in the full regalia of general relativity. Newtonian gravitation is a special case of general relativity, in the limit of small masses and velocities, and thus it is acceptable for analyzing a falling hammer and feather on Earth. Newtonian gravitation is not, however, correct in general.

There is no such thing as space-time curvature.

Of course there is. It can be measured.

- Warren

 

[urtalkinstupid]

No, we think we are measuring it. Ooh, if Newton's equation so good why is it not applicable to large scale objects. No, wait it does. It explains how planets stay in orbit. Which is explained differently by Einstein. Objects fall into the space-time curvature of the sun, and roll aroudn the sun like a marble rolling around the center of the drain never falling in.

What property of matter or energy knows what to do when it is in space? How does it know to curve the space around it with respect to time? Give me a four dimensional model of space-time curving and I will be satisfied. Until then, don't expect me to believe you. I'm sure this theory has been in place long enough to provide a great model of it's happening.

There are so many things that make a mockery of the current proposed science theories. Why? They are so unreal, they are able to fit into fiction based productions.

 

[chroot]

No, we think we are measuring it.

In principle, it can be directly measured. You can draw a large enough circle and observe that the ratio of its circumference to diameter is no longer pi. You could draw a large enough triangle and observe that the sum of its angles is no longer 180 degrees. I don't know how else you'd explain those sorts of observations.

Ooh, if Newton's equation so good why is it not applicable to large scale objects. No, wait it does.

It's applicable, but it's still not exactly correct. Newtonian gravity is an approximation of general relativity when masses and velocities are small. It's much easier to calculate things with Newtonian model than with general relativity, so we use the Newtonian model for situations in which its answers are negligibly different. For the most part, Newtonian gravity is all we need to explain the solar system. The probes that we've sent to Jupiter and Saturn, for example, required nothing more than the Newtonian model to calculate how their engine firings would move them through the solar system. The same trajectories could have been calculated with the full computational power of general relativity, but for little gain: the final positions would have differed only by centimeters or less.

There are several subtle phenomena in the solar system which cannot be explained by Newtonian gravity, however. The two most important are the perihelion advance of Mercury, and the bending of starlight near the limb of the Sun. The full power of the general theory of relativity is necessary to explain those phenomena.

What property of matter or energy knows what to do when it is in space? How does it know to curve the space around it with respect to time?

I'm afraid it's a silly endeavor to try to ascribe human properties to lumps of matter. The lumps of matter doesn't "know" anything. The universe just happens to work this way, in the same way it just happens to have two kinds of electrical charge, and so on. You can just invoke the anthropic principle if you're inclined to worry about such things.

Give me a four dimensional model of space-time curving and I will be satisfied.

G_{\mu\nu} = T_{\mu\nu}

That's the entire model. That's all you need to model every gravitational phenomenon currently known.

Until then, don't expect me to believe you. I'm sure this theory has been in place long enough to provide a great model of it's happening.

To scientists, "theory" and "model" are essentially the same thing. A theory that cannot make predictions is useless.

There are so many things that make a mockery of the current proposed science theories. Why? They are so unreal, they are able to fit into fiction based productions.

You seem to understand very little about current scientific theories, so it's no wonder you think they're "unreal." You're just beating strawmen. It's pathetic, really.

- Warren

 

[chroot]

It's kind of obvious the current theories are not taken seriously. I mean for one, you have all of these science fiction shows that try to make science more than what it is, because what's science now can easily be manipulate into fiction. With a reality based theory there would be less fiction uprisings in the form of movies, shows, and books.

By the way, this is a positively atrocious argument. How can you possibly know what kind of science fiction writers would dream up if we had a different dominant scientific model? Are you psychic?

You can't judge a theory by the caricatures of it written by science fiction writers any more than you can judge a political candidate by the satirical cartoons drawn about him in the newspaper. Surely you must be joking...

- Warren

 

[urtalkinstupid]

How about a visual model?

 

[chroot]

How about a visual model?

What's a "visual model?"

Let me guess -- you're going to claim that because humans can't visualize a four-dimensional space, that such a space can't exist.

Are you also going to claim that because humans can't visualize a square root, that square roots don't exist?

- Warren

 

[Entropy]

This space-time curvature is still a mutual attraction through two objects. One massive object curves space, the other near by object goes down the incline. An attraction is made through space-time curvature. There is no such thing as space-time curvature.

Its not an attraction for the last time. They only appear to move from your 4 dimensional perspective of the universe. I remember someone explaining this really well I'll try to find there post.

Can this explain
the weight of objects in our hands or the energy expended by
gravity as it drives the dynamics of the universe? Where is the
apparently unlimited power source for it all?

There is no energy required! I suppose charged particles have unlimited power as well since they're always exerting forces on each other? Who ever wrote this was a moron.

No, we think we are measuring it. Ooh, if Newton's equation so good why is it not applicable to large scale objects. No, wait it does. It explains how planets stay in orbit. Which is explained differently by Einstein. Objects fall into the space-time curvature of the sun, and roll aroudn the sun like a marble rolling around the center of the drain never falling in.

Newton's equations don't work for objects at high velocities or for extremely massive objects, due to time dilation. But for basic astronomy Newton's errors aren't noticable so that's why we use them for many basic things.

What property of matter or energy knows what to do when it is in space? How does it know to curve the space around it with respect to time? Give me a four dimensional model of space-time curving and I will be satisfied. Until then, don't expect me to believe you. I'm sure this theory has been in place long enough to provide a great model of it's happening.

What property of matter makes it exist? How does time know to run forward? How do two unlike charges know they should be attracted to one another? How do strings know how to wave? Dude you're retreating into philosophy. No theory is ever going to explain all the mechanisms in the universe with every little detail, atleast not in our life time.

There are so many things that make a mockery of the current proposed science theories. Why? They are so unreal, they are able to fit into fiction based productions.

Are you saying that because something like Star Trek or Babylon 5 uses terms like "wormhole" or "warp-drive" that the current theories actually support them? Dude they just throw in that stuff with their falasies to make it sound "sciency" for the layman.

 

[Nereid]

If gravity were a pull, tell me why the Universe is expanding?

You asked this question on your other thread, and I answered it; did you read my answer? Are there parts of that answer you don't follow?

I must say it's really quite tiresome to spend the time and energy to answer good questions, only to find that, a week or so later, you ask exactly the same question again.

Note to chroot: I don't think there's been anything new - other than the 'fun' paper urtalkinstupid posted a few days ago (and my questions on which remain unanswered by urtalkinstupid) - here in this thread for some time; bring it to an end?

 

[russ_watters]

Why don't you do an experiment? It doesn't require much in the way of apparatus to show this to be false. All objects fall with the same acceleration in a vacuum. This very demonstration is shown yearly to thousands of freshmen at universities around the word... but wait, you haven't even completed high school yet.

Are you saying your eighth grade science class didn't have a vacuum pump and plexiglass cylinder? Mine did. Precocious as they think they are, these guys missed a lot of what they were taught years ago.

 

[ArmoSkater87]

lol, my 9th grade science teacher did that with a penny and a feather. It was pretty neat seeing the feather fall down as fast as the penny. I actually saw it again just this past year in 11th grade when I took physics.

 

[urtalkinstupid]

Does the "pull" theory of gravity require energy to hold objects in place?

 

[chroot]

Could you be more specific, urtalkinstupid?

- Warren

 

[urtalkinstupid]

Do objects expend energy when pulling other objects to them through gravitational forces?

 

[chroot]

When two objects move closer, they lose potential energy and gain kinetic energy. Thus, it hurts when you drop a brick on your foot.

- Warren

 

[urtalkinstupid]

You've failed to answer my question. Does a mass use energy to pull another mass closer? Like the Earth keeps the moon in orbit. Does the Earth's gravitational pull on the moon require energy to keep pulling the moon towards Earth in a circle?

 

[ArmoSkater87]

obviously not...the rotation of the moon around the Earth is the affect of spacetime curvature and angular momentum. They balance each other out. The moon doesn't need energy to keep going because of Neutons first law.

 

[urtalkinstupid]

What cause the moon to not fall into the space-time curvature the Earth has created. Use the rubber sheet example. You place a bowling ball in the middle with slightly smaller balls around it...everything falls into the middle.

 

[Nereid]

'Space' is very thin gas (actually a plasma); the Earth and the Moon are massive and dense (compared to the plasma through which they move). How much friction do you think such a thin gas would create?

The Moon would 'fall' into the Earth if it had no net transverse (i.e. non-radial) motion wrt the Earth. However, it does have such motion.

If the only forces acting on the Earth-Moon system were gravitational and friction due to motion through the thin gas, how long would it take for the two to spiral in and collide? Please state your assumptions.

 

[russ_watters]

What cause the moon to not fall into the space-time curvature the Earth has created. Use the rubber sheet example. You place a bowling ball in the middle with slightly smaller balls around it...everything falls into the middle.

What if the slightly smaller balls are moving? Do they still fall toward the bowling ball?

 

[chroot]

You've failed to answer my question. Does a mass use energy to pull another mass closer? Like the Earth keeps the moon in orbit. Does the Earth's gravitational pull on the moon require energy to keep pulling the moon towards Earth in a circle?

No. Gravity is a conservative force. It requires energy to launch a rocket into orbit from the surface, but no additional energy is required once it is in orbit.

How does the Earth keep the Moon in orbit? The standard pedagogy is to study bullet trajectories. If you fire a bullet at a modest speed, it makes a graceful parabola and falls back to the ground. If the bullet is traveling pretty fast, it might go several hundred miles before hitting the ground. The Earth's surface is curved, however, not flat. As the bullet flies, the surface of the Earth is effectively curving away from the bullet. If you fire the bullet fast enough (about 17,000 mph), it's moving so fast that the Earth's surface is curving away as fast as the bullet is falling. The bullet is in orbit. Here's a little Java applet that let's you simulate firing a bullet at different speeds:

http://webphysics.ph.msstate.edu/javamirror/ntnujava/projectileOrbit/projectileOrbit.html

Try firing at different speeds and see if you can recognize the boundary condition between "projectile" and "satellite."

- Warren

 

[beatrix kiddo]

doesn't it take energy to set that bullet in motion? and wouldn't it take energy to keep the planets moving around the sun so they don't fall into it??

 

[chroot]

doesn't it take energy to set that bullet in motion?

It takes energy to get the bullet moving; it requires no additional energy to keep it moving. This is Newton's first law of motion, the law of inertia. If you neglect the small amount of atmospheric drag, a satellite in low-Earth orbit will remain in that orbit forever with no effort.

and wouldn't it take energy to keep the planets moving around the sun so they don't fall into it??

No. You seem to have some very serious misunderstandings of the theory you claim to want to overthrow.

- Warren

 

[Chronos]

Do objects expend energy when pulling other objects to them through gravitational forces?

Assuming I understand the gist of this question, no, at least not in the classical sense of 'work' being performed. A similar example would be a permanent magnet. A magnet does no work when exerting attractive force on a magnetic object. If it did, it would generate heat [an easily tested proposition].