Gravity with mass or density?

[CraigD]

The gradient of the field always goes toward infinity, approaching the Schwarzschild radius.

I don’t believe this is true. I agree with Infy.

 

The Schwarzschild radius [math]r[/math] of a body B of mass [math]M[/math] is

[math]r = \frac{2GM}{c^2}[/math]

 

The force [math]F[/math] experienced at the event horizon of B by 2 connected bodies of mass m separated by distance L in the direction of the center of mass of the body, is

[math]F = GMm \left (\frac{1}{r^2} – \frac{1}{(r+L)^2} \right)[/math].

Substitution and ignoring the smaller terms we can say [math]F[/math] is roughly proportional to [math]\frac{1}{M^2}[/math].

 

Some order-of-magnitude calculations, using [math]m[/math]=50 kg, [math]L[/math]=1 m - roughly a human being:

B                M (kg)  r (m)  F (N)
Planet           10^25   10^-2  10^20
Star             10^31   10^4   10^10
Globular Cluster 10^37   10^10  10^-2
Galaxy           10^42   10^15  10^-12
Universe         10^53   10^26  10^-34

[Qfwfq]

Crag, the LaTeX gets goofed by those alignment tags so I'll repeat your equations without them:

 

[math]F = GMm (\frac{1}{r^2} – \frac{1}{(r+L)^2} )[/math].

 

[math]F= frac{mc^2L}{\frac{2GM}{c^2+L}} ( 1 + \frac{c^2L}{4GM} ) [/math]

 

Now in the first you are applying Newton's force right at the event horizon. The Schwarzschild solution is asymptotic to this in the large r limit, the event horizon is exactly where they differ the most. What you are doing, for increasing M, is essentially just considering the gradient of Newton's force at r proportional to M so it's obvious that you get a decreasing value.

 

Now the event horizon or Schwarzchild radius is that at which the solution is singular. The potential and all its r-derivatives (including the force and its gradient) have infinite limit.

 

No, they still get goofed, there's something else wrong with the LaTeX here.

[infamous]

Einsteins's theory of GR predicts that though the gravitational field around a massive black hole is stronger on the large scale, it will exert weaker tidal forces than it's smaller counterpart. Taking this factor to the extreme, say in the case of a black hole with a radius on the order of a significent fraction of our universe, crossing the event horizon would subject our space traveler to very small tidal forces. Once inside this supermassive black hole, things might appear much the same as they do in the heavily congested area of the inner portion of our own galaxy. A black hole of this size would not need to consist of super dense material. All thats required is enough gravitational force to limit light energy from reaching excape velocity. This concept can be applied to our own universe, it consists of mostly space yet, can be vaguely defined as a gigantic black hole................................Infy

While scanning through the website; AstronomyCafe, I came across an article today which lends support to the issue I proposed in the quote above. Following is the address......

 

http://www.astronomycafe.net/qadir/q2380.html

 

Hopefully, this information will clear-up any confusion...........Infy

[hallenrm]

While scanning through the website; AstronomyCafe, I came across an article today which lends support to the issue I proposed in the quote above. Following is the address......

 

http://www.astronomycafe.net/qadir/q2380.html

 

Hopefully, this information will clear-up any confusion...........Infy

 

Your experience is an evidence for my hypothesis, that thoughts are not created or destroyed, they move across space, all that is neccesary to catch a thought, is a mind properly tuned for it. :)

[CraigD]

Your experience [infamous’s scanning of AstronomyCafe?] is an evidence for my hypothesis, that thoughts are not created or destroyed, they move across space, all that is neccesary to catch a thought, is a mind properly tuned for it. :)

How does Infy’s experience, or information about the gravitational gradient near the event horizons of black holes, support the hypothesis that thoughts exist independently of brains or other “thinking hardware”?

 

(This should, I think, be a separate thread)

[Farsight]

Does anybody know anything about any theories or postulates about gravity being some kind of flow? I'm thinking about equivalence, and maybe it's more than just equivalence, it's the same. A bit wild I know, but I'd appreciate any pointers.

[CraigD]

If by “gravity as a flow”, you mean an model in which objects with mass are “carried” by gravity in a way analogous to bits of floating wood carried by the water in a river, then the only ideas like that of which I’m aware are my own back-of-the-mind musings that the Higgs particle, which some theorists believe explains inertia, may be somehow responsible for gravity, and that perhaps the search for the elusive graviton is looking for a particle that has already, nearly, been found.

 

When I drag the idea from the back of my mind to the fore, problems with it become apparent. The greatest problem is that objects experiencing gravitational acceleration don’t move very much like objects carried in a stream. In a stream, all nearby objects have the same velocity. Under gravity, however, they don’t. If you drop an object in a stream, then, as it passes a point a few minutes downstream, drop another, the two objects float along beside each other. If you release an object from one height, then, as it passes a point a few seconds below, drop another, the first object is moving faster, and continues to move faster, than the second, and they are only briefly near one another.

[infamous]

Does anybody know anything about any theories or postulates about gravity being some kind of flow?

Rationalizing gravity as a flow would be rather difficult Popular but it could in some respects be understood as a pressure. And I'm not talking about the typical Aether theories of the past. Every square inch of empty space is flush with energy in the form of field. This ofcourse cannot be absolutely proved because one would have to examine every square inch of the total volume of our entire universe to do so. Nevertheless, many scientists believe that there is no space empty of field. There are others which believe that there may exist some space empty of field but proving this is equally difficult. Until someone finds proof to the contrary, I lean in the direction of 'No space empty of field'. Assuming this point of view is true, I can imagine a universal pressure existing within our universe. An ambient pressure which might cause the effects we determine as gravity. In the event someone accuses me of making a baseless claim, I must clarify that these are not claims. They are only speculations but speculations which do have some degree of base. Following are a few reasons why I think this view deserves more thought.

 

#1.....The universe is expanding, therefore a residual field pressure resulting from the big bang might be responsible.

#2.....A great number of scientists believe that there is no space empty of field and if true, may be the underlying cause of gravity.

#3.....Without leaning upon Aether theory, one might understand this field pressure as purely geometric in character without the neccessity of discovering the sea of particles needed to explain an Aether theory.

 

Far be it from me to declare these few ideas as scientific gospel. I welcome any and all input with discovery as the goal in mind. Take what I have offered as ideas from a layman, I have no degrees in physics or mathematics. I will not be offended by correction, I'm sure I may be mistaken on some issues. All I ask is that those who read this post undertake an honest evaluation of the points I've offered and resist being insulting with their disagreements..............................Infy

[HydrogenBond]

If one integrates the gravity force vectors in the center of a sphere of uniform mass, they cancel in the center of gravity. Yet if one measures the gravity between two similar spheres, it is done via the center of mass. It is strange the place with no gravity (center) is the place where the gravity has an accumulative impact on distance spheres.

 

One way to explain this is that gravity is more than a force. The center of gravity is not only subject to vector addtion but ralso the sum of all the waves common from all directions. In other words, two waves coming from opposite direction can not only cancel, but can all add. It cancels for one spheres but is addtive when there are two spheres present. The center of gravity between two spheres only cancels because there is no matter present in the center of gravity.

[infamous]

The center of gravity between two spheres only cancels because there is no matter present in the center of gravity.

Might this be, because field pressure between the two spheres is shaded by the mass of one from the other, resulting in the migration of both towards the shaded area, namely; toward each other?........................Infy

[Farsight]

Thanks for the input guys. I'm tussling with the implications of that essay I wrote on time.

 

I just can't enthuse about the Higgs particle, Craig. I've always thought about gravity in terms of geometry, and now I'm trying to look beyond geometry, messenger particles still don't light my fire. Points noted about stream flow though, thanks.

 

I've got some thoughts on energy, infamous, which tie in with what you were saying about pressure, but I can't see how it relates to gravity.

 

But I'll have to get back to you properly later because I'm at work. I so wish I had more time for this.

[infamous]

 

I've got some thoughts on energy, infamous, which tie in with what you were saying about pressure, but I can't see how it relates to gravity.

 

Happened upon this website while searching for information on Zero Point Energy Pressure, and I thought it might shed some additional light on the issue of the gravitational relationships.

 

http://www.ldolphin.org/zpe.html

 

enjoy..........................Infy

[Farsight]

There was an interesting article in New Scientist this week, called Gravity's Secret. Shades of Podkletnov, but it does quote some papers.

 

http://www.newscientist.com/channel/fundamentals/mg19225771.800-gravitys-secret.html

 

More fundamentally, Overduin points out that introducing massive gravitons into physics could cause more problems than it solves. "A massive graviton would mean that you had to rewrite the entire standard model of particle physics," he says.

 

http://www.arxiv.org/abs/gr-qc/0610015