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Gravity: What Is It?

Hmmmm...

General relativity predicts that heavy bodies moving under the influence of gravity emit gravitational waves. Like light waves, they carry energy away from the objects that emit them. However, the rate of energy loss is extremely low, hence very difficult to observe. For instance, the emission of gravitational waves is causing the Earth to slowly spiral towards the Sun, but it would take 10(27) years for them to collide!"

P190, Universe In A Nutshell, Stephen Hawkins

So, gravity is slowly dissapating the energy in the universe anyway...
 
Force, not energy

...they will forever be attracted to it if you drop it again. They will accelerate towards the planet. Energy is obviously being applied to them. However, the planet doesn't lose 'gravity' energy if the only force it is applying is gravity...

Rigamarole, interesting questions. However, it appears that two different vectors are being interchanged too freely. Therein may be some confusion. Gravity is a force, which acts differently than energy. The difference is essentially due to the extent of the spatial dimensions in which each acts. Interestingly, dimensional analysis of force and energy by the respective equations of Newton and Einstein indicates the dimensional disparity. Force, it turns out, is the distribution of mass in seven dimensions, whereas energy distributes mass in six. Moreover, energy is more constrained parametrically than force is.

It is useful, perhaps accurate, to think of space-time as consisting of individual units in a vast mesh. The units, or quanta, of space-time only have the property of length, on the order of the Planck scale. That is, a quantum unit of space-time is represented in only one dimension, infinitesimally thick and 4.05E-33 cm long. However, when numerous quanta interrelate among each other, several dimensions result. Even fractal dimensions may explained in such terms. Moreover, mass can only move along a line of space-time. More to the point, gravity itself has an explanation, given the hypothesis outlined here.

Mass affects the "fabric" of space-time, bringing space-time quanta (STQ) together in tetrahedral forms. While STQ that are not in proximity to a mass may have any form, a concentration of tetrahedral forms next to "empty" space tends to impose structure in that space. The structure imposed is radial and concentric with respect to the tetrahedrons of STQ, where the mass is. Of course, the structure of STQ is diminished over distance, that being inherent in radial symmetry. When any other mass (with attendent tetrahedral STQ) would come near the first object, STQ symmetry would intersect. Because the mass travels along the lines formed by STQ, the two masses "attract" due to the intersection of the paths along which each may travel. Remarkably, the present hypothesis is consistent with the string theory of mass. In summary, an elegant dovetailing may be observed with not only with string theory, but quantum theory as well.
 
The reason that gravity waves, gravitrons etc have not been discovered is because they do not exist. It is because any mass in space contracts the area in which it resides that it gives the illusion of pulling objects together. Imagine a 2 dimensional piece of paper representing an area of space. First draw a vertical line in the middle and then a horizontal line to divide the sheet into 4. Call the intersection at the centre of the page point (A). From point (A) measure 4 inches up the vertical and mark this point calling it point (B).
Now place an imaginary planet Earth at point (A). Immediately point (B) is relocated one inch closer to point (A) as the planet contracts the space between point (A) & point (B). Note it is important to realize thet point (B) has not been pulled to Point(A) but that space has been compressed.
Now place an imaginary Moon at point (B). Its not important to calculate or visualize further contractions of space here as the argument is not effected. The argument under consideration now is that the moon does not orbit the earth but in fact always travels in a straight line.
Starting at point (B) the moon is travelling towards the right and its path is parallel to the horizontal line dissecting the page.From point (B) draw a parallel line to the existing horizontal line to show the straight anticipated path of our moon as it travels through space. At a place 6 inches from point (B) along the moons straight line route you can mark a point and call it (C).
From my earlier argument you will see that point (C) will be drawn closer to (A) as the Earth has compressed the space around it. Now we see that whilst the moon has in fact travelled in a straight line, it appears to have begun to orbit the Earth. The truth is that point (C) has moved.
We can complete the straight line orbit by adding point (D)(E) and so on but its the same deal as point (C). This discussion says that the moon starts at a point on the orbit where it finishes. To expand this ,my reasoning says that if you place a mass in empty space the immediate effect is for that mass to draw-in spheres of space around it like linear rods of space formed into hoops with their ends joined or bubbles if your progressing to 3D imagery.
We can go an interesting step further and regress to the flat Earth philosophy (only with an Einstein like twist). Firstly take another piece of paper and draw a circle on it. Now this circle is a 2D representation of the Earth. Mark a point at the centre of the circle and call it (A). Next mark a point at the very top of the world/circle and call it (B). Imagine a person walking clockwise around the Earth to a point 45 degrees around the circumferance to point (C). Now consider, as with the lunar orbit reasoning above, that our walker has been walking on a dead straight line and not in a circle as at first it might appear. It is the centre of mass of the Earth that has relocated point (C) to appear at a point on the circumferance of our circle. If our man keeps walking he will indeed come back to where he started as the linear track of space occupied by the surface or the planet has been formed into a hoop by the presence of Earths mass. Simple don't you think ?...............
 
Well, that´s more or less what Einstein said a hundred years ago. That doesn´t mean gravity waves shouldn´t exist though.
 
Yes you are absolutely right, Einstein's theory of space time does not envisage gravitons and relies only on the geometry in 4 dimensions. One of the great problems of our time is to join quantum theory with relativity theory. Gravitons might not exist but quantum theory predicts them. If the LHC can't find any then quantum theory has big problems.
 
Gravity in itself is a force which does exist, if it didn't exist then the universe would be an ever expanding mixture of hydrogen and helium from the moment of the big bang onwards.
Gravity as we percieve it is caused by massive objects causing distrotions in space time and a good analagy is to imagine a heavy weight on a rubber sheet, only in four dimentions.
 
Now, anyone who knows me well might tell you - correctly - that I'm no award-winning physicist but here's my take on it ...

Gravity - as a subatomic particle might not exist but it patently does exist as an effect of other pyhsical forces. This is similar in phenomenon to a gyroscope. It doesn't have gravity particles or whatever, and it is kept upright by centrifugal effect - note, not force!
Thus, gravity exists (obviously) but as an effect of combined forces and elements, including material mass, movement and - as Einstein impllied - energy supplying movement to mass. What the material mass is can be all sorts of things.

This is a sad admission from one who always wanted to "rediscover" caborite and construct his own starship. If you can get a gravity particle then you can have interaction (and negation) of it.
 
Stormkhan said:
This is a sad admission from one who always wanted to "rediscover" caborite and construct his own starship.
You've been looking for the wrong stuff! It's got a "V" in it, not a "B" - I hope that helps you find it a bit quicker. You could try to contact the inventor, but the last I heard, Professor Cavor was still stuck in the lunar caves, and the Selenites were closing in. Frankly, it wasn't looking good for him...

Back on topic (just about), while the original post is a slightly-more-confusing version of something I was taught at university many years ago, I think I've read it about right. However, the idea that mass contracts space/time does not mean that gravity doesn't exist. Gravity is just a name for whatever mechanism attracts masses over great distances, whether it be waves or whatever. There has to be some means of "transmitting" the effect though, surely - otherwise, how does a mass at B "know" about the mass at point A?
 
The interesting thing about gravity is that it acts instantaniously over any distance, if the sun where to vanish now then the planets in our solar system would start to wander off because of the lack of gravity from the sun immediatly not after the several minutes to afew hours it would take a signal traveling at the speed of light, which is why it has proved so difficult to incorporate a theory of gravity into any postulated Theory of Everything which is the holy grail of physics.
Its like your 4- dimentional sheet of rubber which you have created an indentation in with your massive object has no inertia, so it springs back flat as soon as you remove the massive object.
if you have a large ball bearing on your rubber sheet and a small ball bearing on your rubber sheet they will orbit each other and the gravitational attraction, the size of the depression made in the sheet is proportional to the mass times the inverse of the square of the distance between the two.
 
Where have you heard that gravity should act instantaneously? As far as I know gravity waves have not yet been detected, and they are generally believed to move at light speed, not at infinite speed.
 
A Scientist Takes On Gravity

But what if it’s all an illusion, a sort of cosmic frill, or a side effect of something else going on at deeper levels of reality?

So says Erik Verlinde, 48, a respected string theorist and professor of physics at the University of Amsterdam, whose contention that gravity is indeed an illusion has caused a continuing ruckus among physicists, or at least among those who profess to understand it. Reversing the logic of 300 years of science, he argued in a recent paper, titled “On the Origin of Gravity and the Laws of Newton,” that gravity is a consequence of the venerable laws of thermodynamics, which describe the behavior of heat and gases.

“For me gravity doesn’t exist,” said Dr. Verlinde, who was recently in the United States to explain himself. Not that he can’t fall down, but Dr. Verlinde is among a number of physicists who say that science has been looking at gravity the wrong way and that there is something more basic, from which gravity “emerges,” the way stock markets emerge from the collective behavior of individual investors or that elasticity emerges from the mechanics of atoms.

Looking at gravity from this angle, they say, could shed light on some of the vexing cosmic issues of the day, like the dark energy, a kind of anti-gravity that seems to be speeding up the expansion of the universe, or the dark matter that is supposedly needed to hold galaxies together.

Dr. Verlinde’s argument turns on something you could call the “bad hair day” theory of gravity.

It goes something like this: your hair frizzles in the heat and humidity, because there are more ways for your hair to be curled than to be straight, and nature likes options. So it takes a force to pull hair straight and eliminate nature’s options. Forget curved space or the spooky attraction at a distance described by Isaac Newton’s equations well enough to let us navigate the rings of Saturn, the force we call gravity is simply a byproduct of nature’s propensity to maximize disorder.

Some of the best physicists in the world say they don’t understand Dr. Verlinde’s paper, and many are outright skeptical. But some of those very same physicists say he has provided a fresh perspective on some of the deepest questions in science, namely why space, time and gravity exist at all — even if he has not yet answered them.

“Some people have said it can’t be right, others that it’s right and we already knew it — that it’s right and profound, right and trivial,” Andrew Strominger, a string theorist at Harvard said.

“What you have to say,” he went on, “is that it has inspired a lot of interesting discussions. It’s just a very interesting collection of ideas that touch on things we most profoundly do not understand about our universe. That’s why I liked it.”

The rest of the article is here:

http://www.nytimes.com/2010/07/13/scien ... gewanted=1
 
Thanks for posting that, Zilch.

Very interesting, but it's as woolly as a lorryload of sheep on the way to market! Even Prof Verlinde doesn't seem too clear about it. But as he says “It’s not often you get a chance to say something new about Newton’s laws. I don’t see immediately that I am wrong. That’s enough to go ahead.”

He said friends had encouraged him to stick his neck out and that he had no regrets. “If I am proven wrong, something has been learned anyway. Ignoring it would have been the worst thing.”

And that's how science works.

Another quote I like was from Dr. Padmanabhan: “Gravity is the thermodynamic limit of the statistical mechanics of 'atoms of space-time.'”
I'm thinking of having that tattooed on my arm... ;)
 
I refute it thus! (Continues to lounge in armchair instead of floating up to the ceiling.)
 
I'll use this as my defence if ever i decide to drop a railway sleeper from a motorway bridge onto a passing car....

seriously, it's rubbish
 
If gravity doesn't exist, then neither does levity. A lack of levity would mean that these emoticons would not exist :D :) :lol: , but I can include them in this reply, therefore gravity must exist because its opposite, levity does. ;)
 
So what causes space to wrap around the mass of the Earth, as you phrase it?
 
My first reaction on reading this topic title was "Of course it bloody does!"

Then I re-read it and saw that it said Gravity - not gravy.
 
Pietro_Mercurios said:
SHAYBARSABE said:
Xanatic_ said:
So what causes space to wrap around the mass of the Earth, as you phrase it?

Cats. It's always cats.
It's the static build-up in their fur. That's why they have to rub themselves against things all the time.

But by strapping buttered toast, buttered side up to a cats stomach and back and then dropping the cat, you will create an anti-gravity device.
 
The guy who wrote Dilbert (Scott Adams?) years ago put forward semi-humourously the theory that there is no gravity - the universe (and everything in it) is in fact expanding in all directions at 32ft per second but because its all expanding at exactly the same rate we are unable to notice it directly, we only notice the acceleration which we feel as 'gravity'.
 
Kind of similar to Robert Rankin's theory of why some ghosts appear annually - they're immune from the effects of gravity, and so basically float around in space but within the path of Earth's orbit - then once a year, the Earth runs smack into them so we see them fleetingly :).
 
To me it seems you've mixed up wormholes and Einstein's theories of gravity as space time curvature. If space was folded into a circle like you say, wouldn't you expect light to be moving in circular orbits like the planets as well?
 
There's a quotation in How Mumbo Jumbo Conquered the World by Francis Wheen, from - an English Enlightenment Philosopher, and I'm racking my brains unsuccessfully trying to remember who - which is pretty much a joke on this subject.

Something to do with an increasingly abstract philosophical discussion going late into the night - A raises doubts about the reality of gravity; B invites A to step through the window if so sure of his premises.
 
There's a quotation in How Mumbo Jumbo Conquered the World by Francis Wheen, from - an English Enlightenment Philosopher, and I'm racking my brains unsuccessfully trying to remember who - which is pretty much a joke on this subject.

Something to do with an increasingly abstract philosophical discussion going late into the night - A raises doubts about the reality of gravity; B invites A to step through the window if so sure of his premises.

The reference was to David Hume's Dialogues Concerning Natural Religion, at the opening of Chapter 4. There's another reference to Hume jesting about this later in the chapter.
 
The reference was to David Hume's Dialogues Concerning Natural Religion, at the opening of Chapter 4. There's another reference to Hume jesting about this later in the chapter.

Hume was known for good cheer: he ate and drank a lot and would often booze into the night with his friends.

'Abstract philosophical discussion going late into the night' might well be tongue in cheek.
 
Unfortunately New Scientist is a subscription service. I gave up my paper subscription last year.
 
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