Neutrinos back into the picture?

[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].

 

[beatrix kiddo]

well, the planets maintain the right acceleration so they don't fall into the more massive bodies they approach. if these massive bodies create a drag, wouldn't it require additional energy to maintain the right acceleration so everything doesn't fall into the most massive body in the solar system??

 

[urtalkinstupid]

By work, I'm assuming you are referring to the work equation?

 

[chroot]

well, the planets maintain the right acceleration so they don't fall into the more massive bodies they approach. if these massive bodies create a drag, wouldn't it require additional energy to maintain the right acceleration so everything doesn't fall into the most massive body in the solar system??

What drag are you talking about?

- Warren

 

[beatrix kiddo]

obviously these massive objects are going to start to slow down the less massive objects as they "pull" them closer to their center mass..

 

[Entropy]

well, the planets maintain the right acceleration

They don't maintain acceleration they maintain velocity.

if these massive bodies create a drag, wouldn't it require additional energy to maintain the right acceleration so everything doesn't fall into the most massive body in the solar system??

Well there is drag on just about everything to some degree or another. The planets feel very little drag but still feel it none the less. So yes, eventually they will fall into the sun (but not for a long long long time) unless some other body effects them and changes their orbit.

 

[beatrix kiddo]

so, basically, the planets are slowing down around the sun?? should the years be getting longer or something??

 

[beatrix kiddo]

does NASA keep a record of this slight time change? or does it only become noticeable every 100 years or something?

 

[chroot]

obviously these massive objects are going to start to slow down the less massive objects as they "pull" them closer to their center mass..

If the solar system were a perfect vacuum, there would be no drag forces and the planets would continue to orbit the Sun exactly as they do now, forever, with no energy input.

The solar system is not a perfect vacuum, however. The density of the interplanetary medium is about 5 particles per cubic centimeter, on average. Most of these particles are in orbit around the Sun in the same way the planets are, and thus are more or less stationary with respect to the planets. They produce an extremely tiny amount of drag that does act to slow the planets down. It acts so so slowly that it is entirely negligible over the lifetime of the solar system.

For the sake of planets, which are very, very massive, there is essentially no drag and they are essentially not slowing down.

- Warren

 

[Math Is Hard]

so, basically, the planets are slowing down around the sun?? should the years be getting longer or something??

no - actually they go faster when they are nearer to the sun (approaching perihelion - hope I said that right!). One of Kepler's laws.

 

[chroot]

does NASA keep a record of this slight time change? or does it only become noticeable every 100 years or something?

It would not be measurable with today's technology even over a billion years.

- Warren