How far does gravity reach?

[kurros]

How do you know this? have you ever meassured the radius of curvature of the sun's trajectory? I say any measurement of this radius of cuvature will result in a straight line trajectory - but fear not some theory will produce an appropriate curve.

The distance of the solar system from the centre of the galaxy is well known from parallax measurements as is our orbital velocity. From this we can infer the radius of curvature of the orbit. Yes we cannot tell directly (as far as I know, perhaps some actual astronomer can correct me) that the orbit is elliptical because the orbit is so big and we haven't moved very far since we have been watching, but if it is straight as you suggest then you have to explain why the galaxy still exists and hasn't flown apart in the billions of years it has existed, and how it formed at all. Gravity explains all these things very nicely, although there are the dark matter issues. We might sort that out a bit at the LHC if we are lucky though.

How do you know this? You aren't going to BB us are you?

You don't need to assume a Big Bang to model large scale structure formation in the universe, but you do need expansion. Btw these models, when you include dark matter, match the observed large scale very well and constitute very strong evidence for the existence of dark matter.

maybe gravity is dominant on latge scales, but certainly no infinite scales. Infinite scales have a mathematical reality, perhaps, that is lacking in observational support.

Well of course we can't say anything about truly infinite scales, in fact GR from a cosmological perspective doesn't say gravity extends to infinity. It extends as far as it has had time to travel during the lifetime of the universe, it travels at the speed of light after all. Observation DOES however provide strong evidence that gravity dominates on the largest scales we can observe. There is some room here for corrections to gravity, but not huge corrections such as gravity having a range on the order of the solar system scale would require.

You are discussing theory only - some one taught you this - and on which your post is lacking in physical integration.

It is certainly not just theory. I will find a nice review article on the subject for you if you like, lets see.... ok this seems ok, 0809.3730, gives you all the historical evidence for GR and explains the current problems as well. The introduction should be manageable for you I think. Keep in mind that while the author questions the validity of GR at large scales he doing it in accordance with the evidence and is not denying that gravity is responsible for galaxy and large scale structure formation. He IS pointing out that we lack PRECISION tests, so we don't know quantitatively how well GR explains the observations. Qualitatively it is very good. Also keep in mind that the large scale structure simulations are based on linearised gravity - it is impossible to full GR simulations of these systems, they are way too complex and GR is hard. Nevertheless they still explain the structure very well when you include dark matter. Also, this is an active field of research so people are continuously inproving their simulations and arguing about the results.

 

[quantum_wave]

Here is that PDF:

http://arxiv.org/PS_cache/arxiv/pdf/0809/0809.3730v2.pdf

 

[geistkiesel]

How do you explain the Sun going around the galactic center without gravity?

Is the trajectory of the sun an observed straight line or is it elliptical?

 

[geistkiesel]

Perturbations of planetary orbits due to all planets are predicted and observed but the dominant effects always come from the Sun, Jupiter and the nearest other planets. The motion of Uranus is perturbed by Jupiter, Saturn etc by a noticable amount and it was only after these were taken into account that people realised there's got to be something else tugging on the planet. Similarly, the precession of Mercury is affected by the planets and in computing the fact that Merucy's orbit precesses in a way not explainable by Newton you must include the perturbations from all other planets.

The motion of Earth is not observably effected by the mass forces of Pluto. The star Sirius has no observable effect on the the motion of Earth. The gavitational force of the Sirius-Earth stellar system is observably non-existent- The range of gavity forces is observably limited and all the theories of all cosmologists will not alter this fact.

 

[geistkiesel]

How do you explain the Sun going around the galactic center without gravity?

I have another thought on this, but I have no confidence in its physical reaity, but does not general relativity theory hold that the the motion of stellar entities is geometically modulated?

 

[Dywyddyr]

The range of gavity forces is observably limited and all the theories of all cosmologists will not alter this fact.

Unfortunately that isn't a fact.
It's an assumption based on your misinterpretation.

 

[AlphaNumeric]

The motion of Earth is not observably effected by the mass forces of Pluto.

Read the link I posted.

The star Sirius has no observable effect on the the motion of Earth.

The gravitational interaction of stars with nearby stars is observed through, because its much bigger and easier to spot.

The gavitational force of the Sirius-Earth stellar system is observably non-existent-

Oh, the old "I didn't see it so it obviously doesn't exist" logic. You do realise that physics involves measurement limits, that observations aren't perfect. The effect is beyond our current ability to measure, that doesn't mean they are zero. Quantum field theory says the photon is massless and current experiments put an upper bound on its mass of $$10^{-51}$$ kilograms but that isn't the same as it being shown to be zero. Learn the difference between zero and a non-zero upper bound, $$x=0$$ is different from $$x<\epsilon$$ for small $$\epilson$$.

The range of gavity forces is observably limited and all the theories of all cosmologists will not alter this fact.

You do realise that we see entirely galaxy clusters, spanning tens or hundreds of millions of light years which are gravitationally bound? Our galaxy is gravitationally interacting with Andromeda, 2 million lights years away. Several dwarf galaxies orbit our galaxy, hundreds of thousands of light years away. You have picked an effect known to be very very small and proclaimed it zero while utterly ignoring the huge effect of galaxies on galaxies, seperated by millions of light years.

Well done, you are showing more than your usual level of stupidity. That's like getting blood from a stone!

 

[quantum_wave]

...
Oh, the old "I didn't see it so it obviously doesn't exist" logic. You do realise that physics involves measurement limits, that observations aren't perfect. The effect is beyond our current ability to measure, that doesn't mean they are zero. Quantum field theory says the photon is massless and current experiments put an upper bound on its mass of $$10^{-51}$$ kilograms but that isn't the same as it being shown to be zero. Learn the difference between zero and a non-zero upper bound, $$x=0$$ is different from $$x<\epsilon$$ for small $$\epilson$$.

I think he realizes that, and he did not say that there was no effect.

...
Well done, you are showing more than your usual level of stupidity. That's like getting blood from a stone!

You would then have no blood?

 

[geistkiesel]

Read the link I posted.

The gravitational interaction of stars with nearby stars is observed through, because its much bigger and easier to spot.

Donm't change the subject. I was talking about Sirius v the Earth, not Sirius v other stars. But do Orion and ANtares have an observable gravitational link?
[/quote]

Oh, the old "I didn't see it so it obviously doesn't exist" logic. You do realise that physics involves measurement limits, that observations aren't perfect. The effect is beyond our current ability to measure, that doesn't mean they are zero. Quantum field theory says the photon is massless and current experiments put an upper bound on its mass of $$10^{-51}$$ kilograms but that isn't the same as it being shown to be zero. Learn the difference between zero and a non-zero upper bound, $$x=0$$ is different from $$x<\epsilon$$ for small $$\epilson$$.

We are discussing gravity force ranges - finite or infinite. Get back on the thread or get out of it.

You do realise that we see entirely galaxy clusters, spanning tens or hundreds of millions of light years which are gravitationally bound?

It isn't "I didn't see it therefore it doesn't exist", It is, "I didn't see it therefore it was not observed."

"I]You [/I] [plural right? from 'WE']see galaxy clusters; I see galaxy clusters, now who has measured the gravitational force across any galaxy spanning hundreds of millions of light years? Which of the measurements indicate 'gravitationally bound[ing]?

Our galaxy is gravitationally interacting with Andromeda, 2 million lights years away. Several dwarf galaxies orbit our galaxy, hundreds of thousands of light years away. You have picked an effect known to be very very small and proclaimed it zero while utterly ignoring the huge effect of galaxies on galaxies, seperated by millions of light years.

How do you know Andromeda is gravitationally bound and interacting with our galaxy, and that dwarf galaxies orbit our own galaxy?

Did you read this in your thirty year old copy of "Popular Mechanics", or p'haps in your P.M. crusty crumpits, or tea leaves, or did one of your integrated multidimensional integrals draw provide you a substitute for physical measurement?

Well done, you are showing more than your usual level of stupidity. That's like getting blood from a stone.

Leave it to the prick-head AlphaNumeric to be the first and only source of insults in this thread.

So take your bloody stone metaphor and shove it up your bloody ass.

 

[geistkiesel]

http://www.fortunecity.com/emachines/e11/86/solarsys.html

Describes how the inclusion of Pluto and other small objects in the solar system have not only been included but are essential to knowing the long term configuration of the solar system. Another bit of ignorance from Geist.

Now I get it. You are just dishonest, a scam, a sham, a fake, a fraud. We are discussing the range of gravitational forces nitwit. The force of Pluto's gravity has never been linked to any Earth trajectory perturbation effects.

 

[geistkiesel]

And your magical evidence for this claim is....?

Hey dip shit, I said, NO ONE HAS MADE THE MEASUREMENT. What do you need a peer reviewed paper saying no one has made the observation? You talk like drooling snot-nosed mathematician, as opposed to a, well a mathemathician, but don't take this personally.

 

[geistkiesel]

http://www.fortunecity.com/emachines/e11/86/solarsys.html

Describes how the inclusion of Pluto and other small objects in the solar system have not only been included but are essential to knowing the long term configuration of the solar system. Another bit of ignorance from Geist.

I posted this [below] a few posts back. I should have said that Pluto's gravitational force is not observed to effect Earth's motion..

The planets' mass is 1.3 x 10^-2 of that of the sun tho the angular momentum of the planets is 3.15 x 10^43 and the angular momentum of the sun is 1.6 x 10^41kg-kg-m^2/sec. There are physical paradigms at work other than a simple gravitational model.

The sun is massively much larger than Pluto's, but so what? The gravitational effect between Pluto and Earth is observationally zilch.

 

[geistkiesel]

Originally Posted by geistkiesel
B ut the range of Pluto vs the Sun is finite. ”

Supposition on your part.

A less than optimum choice of words words on mhy part. The gravitational range of Pluto is orders of magnitude less than that of the sun. I say this as the sun is more massive and will be measured at distances far beyond the last mesured gravity force of Pluto.“ The 'finite' word may be striken.

Originally Posted by geistkiesel
"maybe gravity is dominant on latge scales, but certainly no infinite scales. ”

Certainly? Based on...?
To quote you: "The religious forum is elsewhere."

No, I base it on the unavailability of measuring equipment with 'infinite measuring capacity'.

“ Originally Posted by geistkiesel
Near neighbor planet's motion and trajectory may be determined but Pluto doesn't effect Earth. ”

Supposition again.

There is no observed effect, hence the statement "it doesn't effect ."

“ Originally Posted by geistkiesel
The sun is massively much larger than Pluto's, but so what? The gravitational effect between Pluto and Earth is observationally zilch. ”


Evidence?

Thjere is no evidence., is my evidence.

 

[Dywyddyr]

No, I base it on the unavailability of measuring equipment with 'infinite measuring capacity'.

I see, so according to your "logic" the lack of ability to measure something (e.g. in this case we haven't reached infinity to check) makes it certain that that something doesn't exist?
Interesting...

There is no observed effect, hence the statement "it doesn't effect ."

Untrue - see below.
(Besides which "not observed" is NOT the same as "not there").

Thjere is no evidence., is my evidence.

Not quite true.
If Pluto weren't there are you claiming that the Earth would have exactly the same orbit?
Let's see: from the link provide by AlphaNumeric, which you dismissed as "dishonest, a scam, a sham, a fake, a fraud", (and evidently didn't bother to read before deciding it was wrong):

The planets also influence each other's motion, however, all according to the inverse square law. And we can detect these effects although they are small.

And you still haven't replied to this:

Aren't both gravity and E-M subject to the inverse square law? So why would one and not the other be "severely limited"?

 

[geistkiesel]

The distance of the solar system from the centre of the galaxy is well known from parallax measurements as is our orbital velocity. From this we can infer the radius of curvature of the orbit. Yes we cannot tell directly (as far as I know, perhaps some actual astronomer can correct me) that the orbit is elliptical because the orbit is so big and we haven't moved very far since we have been watching, but if it is straight as you suggest then you have to explain why the galaxy still exists and hasn't flown apart in the billions of years it has existed, and how it formed at all. Gravity explains all these things very nicely, although there are the dark matter issues. We might sort that out a bit at the LHC if we are lucky though.

Knowing a distance to center of the galaxy and the orbital velocity does not compute into a radius of curvature. Are there any galaxies, of all the myriad types, that have not flown apart? You are correct it is difficult to merasure curvatures. Using the Big Bang and the 'inflationary stage of expasnsion' where gravity "pushed" and then began "sucking", or so one theory goes. Looking at the scenario of gravitational activity from the assumed BB get-go gravity, as a force, is the least understood of all possible types, which makes theoretical gravitation models, to a high degree of probability, to be the farthest from "accuracy" in describing physical phenomena.

You don't need to assume a Big Bang to model large scale structure formation in the universe, but you do need expansion. Btw these models, when you include dark matter, match the observed large scale very well and constitute very strong evidence for the existence of dark matter.

Ptolemaic models of the planet motion and the predictive power of the system was as accurate as anyone desired, the model simply bore no relation to the actual physical mode of planetary motion.

Well of course we can't say anything about truly infinite scales, in fact GR from a cosmological perspective doesn't say gravity extends to infinity. It extends as far as it has had time to travel during the lifetime of the universe, it travels at the speed of light after all. Observation DOES however provide strong evidence that gravity dominates on the largest scales we can observe. There is some room here for corrections to gravity, but not huge corrections such as gravity having a range on the order of the solar system scale would require.

Here is a link discussing in detgail the matter of the speed of gravity, which is different than your model.
http://www.metaresearch.org/cosmology/speed_of_gravity.asp

leaving that issue for another day it seems contradictory that gravity forces are preceding the universes's expansion. Gravity is a mass-mass effect, hence , in your model, or whoever constructed the model, gravity has nothing to expand to, meaning no mass-mass effects are possible. The model you described seems much like an artificial mirror image of Maxwell's equationas re electrostatic potential.

It is certainly not just theory. I will find a nice review article on the subject for you if you like, lets see.... ok this seems ok, 0809.3730, gives you all the historical evidence for GR and explains the current problems as well. The introduction should be manageable for you I think. Keep in mind that while the author questions the validity of GR at large scales he doing it in accordance with the evidence and is not denying that gravity is responsible for galaxy and large scale structure formation. He IS pointing out that we lack PRECISION tests, so we don't know quantitatively how well GR explains the observations. Qualitatively it is very good. Also keep in mind that the large scale structure simulations are based on linearised gravity - it is impossible to full GR simulations of these systems, they are way too complex and GR is hard. Nevertheless they still explain the structure very well when you include dark matter. Also, this is an active field of research so people are continuously inproving their simulations and arguing about the results.

I follow your discussion, but GR and I have parted ways. That the model you discuss here use 'linearized' gravity poses many potential poroblems, analogous to redoing Mother Nature's effort just to dovetail with a theory. This may be an exageration, but I am sure you get my point. It seems, without more than your description to go on, that gravity is presumed to extend infinitely and if there is any "inverse distance squared" effects to what would the gravity field distance be measured in the ultimate vacuum of pure nothingness?

I am not an anti-modelist, but I have written enough software to understand that models without accompanying source code, are scientifically worthless and are convincing most easily to the general public (and some scientists well).

The link I brought to this post should be interesting to you as you do not appear to have learned the rules of dogmatic robotic absolutism. The link, if for no other reason is interesting and it provides a slightly different angle for the reflection of mental radiation protocols.

 

[AlphaNumeric]

...

Wow, you managed a whole post without accusing me of having a mental illness or planning a killing spree. Is it a full moon or something?

Donm't change the subject. I was talking about Sirius v the Earth, not Sirius v other stars. But do Orion and ANtares have an observable gravitational link?

So because something is beyond our current level of observation then it doesn't exist? And how does pointing out gravity extended millions of light years 'change the subject'? Or was it just too obvious a counter to your claims that you're going to pretend I didn't say it?

We are discussing gravity force ranges - finite or infinite. Get back on the thread or get out of it.

Wow, you really can't accept it when someone explains why you're wrong.

I explained to you why something being small doesn't mean it's zero. I can't see bacteria, does that mean they don't exist? Just because you can't see something with a binoculars doesn't mean it isn't there. Just because we can't currently measure the gravitational interaction between two distant stars doesn't mean it isn't there. The precise measurement of position and motion of objects trillions of metres away and millions of metres across is quite hard you know. Oh wait, you don't know. Like usual.

It isn't "I didn't see it therefore it doesn't exist", It is, "I didn't see it therefore it was not observed."

"I]You [/i] [plural right? from 'WE']see galaxy clusters; I see galaxy clusters, now who has measured the gravitational force across any galaxy spanning hundreds of millions of light years? Which of the measurements indicate 'gravitationally bound[ing]?

Yes, I tend to say 'we' when referring to a group of people, of which I am a part, which has more than one person on it. It's a pronoun I'd have thought you'd have seen before.

As for the measurements, see the references of http://en.wikipedia.org/wiki/Galaxy_groups_and_clusters . I know, I know, Googling phrases like 'galaxy clusters' is so counter intuitive it escaped you but at least try.

It isn't "I didn't see it therefore it doesn't exist", It is, "I didn't see it therefore it was not observed."

"I]You [/i] [plural right? from 'WE']How do you know Andromeda is gravitationally bound and interacting with our galaxy, and that dwarf galaxies orbit our own galaxy?

I didn't say Andromeda was gravitationally bound to our galaxy.

And we know that galaxies and their satellites interact because they visibly tug on one another. http://en.wikipedia.org/wiki/Interacting_galaxies

Did you read this in your thirty year old copy of "Popular Mechanics", or p'haps in your P.M. crusty crumpits, or tea leaves, or did one of your integrated multidimensional integrals draw provide you a substitute for physical measurement?

Oh good one. Try to insult me by saying "OMG, you read books!". Do you really think that I'm ashamed of the fact I bother to learn things and read the work of others? Do you really think I'm ashamed of the fact I check to see what work people have done or what measurements people have made if I'm not sure?

You could have found out that satellite galaxies and the galaxies they orbit visibly tug on one another in about 7 seconds if you'd bothered to use Google. But no, you just made claims which you didn't back up because they are false and thus you show your ignorance, your unwillingness to learn and your close mindedness. Well done you.

Leave it to the prick-head AlphaNumeric to be the first and only source of insults in this thread.

So take your bloody stone metaphor and shove it up your bloody ass.

Wow, are you trying to be ironic? You do realise if you call me 'prick-head' it is an insult (or an attempt) so then saying "the only source of insults in this thread" kind of makes you look a little stupid, don't you think?

But hey, I suppose you're all out of ideas about why you should ignore what I said and why you're so ignorant. Calling you ignorant isn't an insult, it's a statement of fact.

You are just dishonest, a scam, a sham, a fake, a fraud.

Maybe I'm learning it from you. Like when you claim you know vector calculus and then bugger up your attempted disproof of the Shell Theorem. Or how you make claims about cosmology in this thread but offer no evidence and then ignore every person who proves you wrong.

If you want to go toe to toe on some vector calc Geist I'm only too happy. You know, put up or shut up. I have nothing to hide.

Hey dip shit, I said, NO ONE HAS MADE THE MEASUREMENT. What do you need a peer reviewed paper saying no one has made the observation? You talk like drooling snot-nosed mathematician, as opposed to a, well a mathemathician, but don't take this personally.

What were you sdaying about me being the only source of insults?

And yes, a peer reviewed paper would be nice. It's just you utterly fail to back up anything you say. And even if noone has done that measurement the interaction of galaxies proves you wrong. If gravity doesn't extend from Pluto to Earth, a few AU, why does it extend light years and cause galaxies for form? Magic?

And you can throw every insult under the Sun at me Geist, the fact is I'm a trillion times the physicist you'll ever be

 

[geistkiesel]

I see, so according to your "logic" the lack of ability to measure something (e.g. in this case we haven't reached infinity to check) makes it certain that that something doesn't exist?
Interesting...

If a 10 kg mass is suspended on a string 100 meters land a 1000kg mass is susoended on an equal length string and the masses are separated by a distance the diameter of out solar system, and the weights are observed to remain motionless, the absence of motion is sufficient to conclude there is no effect for the particlular mass-mass system at the particlular disance noted.

Untrue - see below.
(Besides which "not observed" is NOT the same as "not there").


Not quite true.
If Pluto weren't there are you claiming that the Earth would have exactly the same orbit?
Let's see: from the link provide by AlphaNumeric, which you dismissed as "dishonest, a scam, a sham, a fake, a fraud", (and evidently didn't bother to read before deciding it was wrong):


And you still haven't replied to this:

When I say unobserved, I mean not there. If later something is observed then 'it is there.,

 

[geistkiesel]

Dywyddyr,

The very first wiords of the link is pasted below.

This article does not cite any references or sources.
Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2006)

Now just what would you have me discuss about this important document?

 

[Dywyddyr]

If a 10 kg mass is suspended on a string 100 meters land a 1000kg mass is susoended on an equal length string and the masses are separated by a distance the diameter of out solar system, and the weights are observed to remain motionless, the absence of motion is sufficient to conclude there is no effect for the particlular mass-mass system at the particlular disance noted.

Depends upon the sensitivity of the measuring instrument doesn't it?
"Not measured/ observed" is NOT the same as "not there".

When I say unobserved, I mean not there. If later something is observed then 'it is there.,

So it just appears?
For your information: in the English language "unobserved" has a completely different meaning from "not there".
I've never observed the header tank for water in my flat, but I'm damn sure it is there.

mental radiation protocols

WTF???

The very first wiords of the link is pasted below.

This article does not cite any references or sources.
Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2006)

Now just what would you have me discuss about this important document?

Oops, wrong.
The actual first words are:

Is the Solar System stable?
Carl Murray
You might be surprised to learn that the Earth's orbit round the Sun, like those of other planets,is chaotic. What does this mean for the future of the Solar System?

No mention at all of anything you state.
Read it again.

 

[quantum_wave]

Wow, you managed a whole post without accusing me of having a mental illness or planning a killing spree. Is it a full moon or something?

Well, yes it is, but maybe it is the new me. Too bad it is the old you .

But if you take my point, you again read into what he said only what you wanted to hear, and not what was obviously the intent. You should be able to admit it when you are called on it though. Geist is being a bit loose on the details and he admits if but if you actually wanted to you would get his point.