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What causes gravity? |
Drafell
Grand Admiral
Mythica
Joined: May 30, 2003
Posts: 2449
From: United Kingdom
|  Posted: 2008-03-11 10:11
I was thinking about what would cause gravity, and why it is so relatively weak when compared to the other forces after seeing a documentary on Stephen Hawking last night.
I asked myself a simple question - What if gravity isn't a force, but a side effect? What would cause this effect?
According to string theory, everything in the universe is supposed to be made up of vibrating 'strings', would gravity be a manifestation of these vibrations interacting with each other?
And then I thought about dark matter, this mysterious form of matter or energy that no one has yet been able to observe, although apparently we can observe the effects of it through gravitational lensing bending light over large voids and distances.
Then it occured to me... if there are gravity "waves" that distort space and time, maybe gravity is essentially just a manifestation of drag. When a boat moves through water, it displaces an amount of water and also suffers from drag and friction. The faster you go, the bigger effect you will cause, creating bigger and bigger waves. This is apparently what is predicted to happen when you try to accelerate an object to near "C" velocities.
Maybe gravity is what happens when you get large volumes of physical matter and energy moving through this dark matter - therefore creating the "drag" effect which we perceive as gravity.
There are probably a load of logic flaws in this arguement, but I think that it would maybe explain the relative weakness of gravity compared to the other forces.
What do you guys think? And am I just rehashing old theories?
[ This Message was edited by: Drafell on 2008-03-11 10:14 ]
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YIIMM
Grand Admiral
Joined: June 16, 2005
Posts: 851
From: Barcino, Hispania Tarraconensis
| Posted: 2008-03-11 11:15
The best analogy I've heard about gravity is that it acts as if space is a flat, elastic surface (like a trampoline or a matress). More massive objects sink lower down, so things passing by get caught in the dip and are drawn in.
I know it's probably not like that at all, but it's yet one more thing I've learned from Calvin and Hobbes.
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Mastakazam *P2*
2nd Rear Admiral
Joined: May 27, 2006
Posts: 26
From: Pickering, Ontario, Canada, Metaverse
| Posted: 2008-03-11 11:33
Funny you should think such an idea.. reminds me of some scientists who believed that light is a wave and as such must travel through a medium, through which the earth and everything traveled. Their idea was that the planet would disrupt the ether so light wouldn't behave exactly the same on two points of the world, or something like that... I don't know how but they did experiments based on that, and ended up only proving that their theory was probably false.
...well, your description of the earth leaving a wake in space made me imagine something that reminded me of this xD
I watched a really good video once which talked all about string theory, and also posed that question and some ideas... I think the leading theory was something like, gravity is created from massy objects by them emitting 'gravitons' which cause an attractive force (I forget if they had more detail on that) and the reason why it's so weak is that perhaps gravitons travel not just through space but also through dimensions.. yes, by which it means other copies/versions of the universe!
Oh yeah, the video also explained that they figure that strings regularly travel and exist along not just our regular 4 dimensions (3 spacial dimensions, and 1 of time) but also 6 other spacial dimenions... and then one more dimension which is the 'barrier' between universes...
It was a while ago when I watched it, and I can't remember the name but it was great! When I find that DVD I'll come back and name it, I highly recommend it to anyone that's interested!
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Fattierob
Vice Admiral
Joined: April 25, 2003
Posts: 4059
| Posted: 2008-03-11 11:42
Quote:
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On 2008-03-11 10:11, Drafell wrote:
Maybe gravity is what happens when you get large volumes of physical matter and energy moving through this dark matter - therefore creating the "drag" effect which we perceive as gravity.
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Drags, or frictions, force works in the opposite direction of force applied. So, if earth was moving 50 m/s "that way" their'd be a drag in the oppostie of "that way"
Quote:
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There are probably a load of logic flaws in this arguement, but I think that it would maybe explain the relative weakness of gravity compared to the other forces.
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Theirs an actual equation to find the gravity between two objects.
However, it uses a "Gravitational Constant" which might explain this "drag" effect you are thinking up of.
http://en.wikipedia.org/wiki/Gravitational_constant
on a side note, nobody here is a physicist.
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Kanman
Grand Admiral
Pitch Black
Joined: August 26, 2005
Posts: 1017
From: Virginia, United States
| Posted: 2008-03-11 12:33
Gravity is weak compared to other forces. That is absolutely true. Currently, the best explanation for that is rather mind-bending. This theory is supported by mathematical equations that cover whole walls, but of course is beyond our ability to test or prove at this time.
It comes back to those superstrings you mentioned. Someone suggested that perhaps gravity was 'leaking' out of our universe, into the extra-dimensional space that we and all the other universes inhabit. This proved to not work out, however they then turned it around, considering that perhaps it is leaking IN. THIS looked to be correct via mathematics. It would seem that the force of gravity is not a feature of our universe at all, but rather a faint influence of the physics of another universe (in which we could expect gravity to be much stronger).
So, to make it simple, imagine the universe is a song being played. gravity is not an instrument in our song, but the neighbor is playing their own music, very loudly, and are using gravity in their song. We can kind of hear it while we listen to our music, but its pretty faint.
Like I said, this is just a theory without experimental proof, and so may well be proven 'crazy talk' in a matter of years, but it's the best we have.
As for dark matter, it cannot be what causes gravity because we can feel its gravity too. That is how we know it is there. We cannot detect it, see it or anything, but we can see its gravitational influence on what we can see. Stephen Hawking suggests that in one of the extra spacial dimensions of our universe (10 total spacial dimensions at last count) the universe is VERY small (about a few nanometers wide), and bowed over like a horses saddle. In this construct, a large amount of matter could be 'right here' in the sense that we feel the matter's gravitational influence, but while actually being VERY far away (the other side of the saddle). Again, a theory that works in mathematics, but not tested in experiments.
As for dark energy, that refers to an unknown source of energy in the universe which is fueling the accelleration of our universe's expansion. Not only is the universe getting bigger, but that rate at which it is getting bigger is increasing. This is completely counter to gravity, as gravity woud tend to slow our expansion and pull us back down together. The reason we are so baffled by dark energy is that not all space is expanding evenly, like you would imagine. It is rather the space in between the super clusters (larger groups of galaxies) that is expanding. This space would seem to be completely empty, yet somehow energy and forces are pouring forth from it like a faunt. It is this effect that has caused our super clusters to form threads and filaments, making the 'big picture' of the universe look like a sponge or crazy spider's web.
No, I'm not a physicist, but I was thinking of making it my minor.
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Monkey (USF Exodus)
Fleet Admiral
Lethal Assault Group
Joined: February 06, 2008
Posts: 11
From: UK
| Posted: 2008-03-11 12:44
to put it simply
mass.
any object with mass attracts other objects (with mass) with the fundamental force we call gravity.
the size of the force is goverened by the universal law of gravitation (devised by Newton).
the reason its so small is that the gravitational constant (6.67*10^-11) is very small.
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Xpli$it
Marshal
Joined: March 06, 2004
Posts: 486
From: Canada
| Posted: 2008-03-11 12:59
Quote:
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On 2008-03-11 11:33, Mastakazam *P2* wrote:
...well, your description of the earth leaving a wake in space made me imagine something that reminded me of this xD
I watched a really good video once which talked all about string theory, and also posed that question and some ideas... I think the leading theory was something like, gravity is created from massy objects by them emitting 'gravitons' which cause an attractive force (I forget if they had more detail on that) and the reason why it's so weak is that perhaps gravitons travel not just through space but also through dimensions.. yes, by which it means other copies/versions of the universe!
Oh yeah, the video also explained that they figure that strings regularly travel and exist along not just our regular 4 dimensions (3 spacial dimensions, and 1 of time) but also 6 other spacial dimenions... and then one more dimension which is the 'barrier' between universes...
It was a while ago when I watched it, and I can't remember the name but it was great! When I find that DVD I'll come back and name it, I highly recommend it to anyone that's interested!
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I'm a big fan of einsteins relativity and the string theory, and I think one of my favourited you tube videos is similar (or exact) to what you're talking about. I hope the video is within the boundaries of the RoC, if not, forgive me.
http://www.youtube.com/watch?v=yzMEAkI-yrQ
[ This Message was edited by: Fatal Xpli$it on 2008-03-11 13:03 ]
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Kanman
Grand Admiral
Pitch Black
Joined: August 26, 2005
Posts: 1017
From: Virginia, United States
| Posted: 2008-03-11 13:24
while we are hitting youtube, I have a good one.
http://www.youtube.com/watch?v=DfPeprQ7oGc
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Xpli$it
Marshal
Joined: March 06, 2004
Posts: 486
From: Canada
| Posted: 2008-03-11 15:54
lol @ grade 12 physics
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Fattierob
Vice Admiral
Joined: April 25, 2003
Posts: 4059
| Posted: 2008-03-11 16:37
WHAT?
AN INTERFERENCE PATTERN?
Oh god, I just laughed so hard. The way the voice actor said that, he was actually into it.
hahaha
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jedi42
Grand Admiral
Evil Empires Inc.
Joined: February 25, 2002
Posts: 478
From: jedi42
| Posted: 2008-03-11 21:09
Drafell. The idea you mention in the OP is essentially cosmic ether/luminiferous aether. You can read up on it here:
http://en.wikipedia.org/wiki/Cosmic_ether
A principal result of string theory could be a consistent quantum theory of gravity.
The graviton is contained within string possibilities.
[ This Message was edited by: dj42 {C?} on 2008-03-11 21:14 ]
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Grumpy Dwarf
1st Rear Admiral
Mythica
Joined: December 26, 2007
Posts: 7
From: The Forest or the Mine
| Posted: 2008-03-11 21:40
The natural order of the universe is chaos (or shall I say disorder...). Gravity generally refers to objects attracted to each other (layman version). If the universe is trying to reach an equilibrium state, doesn't it seem very circular that gravity seeks to combine seperate objects into a single mass while theologists in the science department attempt to convince the world that everything is attempting to reach a state of choas to establish equilibrium, being utter disorder?
I do realize this arguement in itself is somewhat circular. Not sure if there is a way around that.
If complete disorder and equilibrium are comparable, it would be logical to conisder an equilibrium scenario where our universe is constantly disorganized at a rate that is steady. I'm gonna go smack my head against the desk... ... ... ... anyone ever noticed how magnetic storage devices (aka HDD) need to be defragmented? Mass? Energy? Disorganization? Blaaaahhhhhh!
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Xpli$it
Marshal
Joined: March 06, 2004
Posts: 486
From: Canada
| Posted: 2008-03-11 22:01
I believe einsteins theory. Objects with mass create a dip in darkmatter which things fall into
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Sardaukar
Admiral
Raven Warriors
Joined: October 08, 2002
Posts: 1656
| Posted: 2008-03-11 23:59
Which theory of gravity supports the idea that if we were to control a quantity of mass so dense that it's gravitational force would warp the very flow of time around it, we would be able tob build a ring around that would take you backwards through time with each circuit, going as far back as the completion of the structure? Something to do with the gravitic force being so strong that inverted time, or another similar phenomenon.
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jedi42
Grand Admiral
Evil Empires Inc.
Joined: February 25, 2002
Posts: 478
From: jedi42
| Posted: 2008-03-12 00:51
In General Relativity, gravitation is not a force but curvature of space-time.
The idea of space-time was Einstein's, and he is responsible for many modern time paradoxes. (i.e. one twin leaves earth near the the speed of light, comes back after traveling 20 light-years, what happens?).
General Relativity breaks down at small scales, though. Quantum field theories, and potentially string theory, are attempts at narrowing the resolution of our understanding of gravity to Planck and sub-Planck lengths, respectively.
Quantum gravity, ultimately, intends to reconcile the electromagnetic, weak, and strong forces (and their corresponding fundamental particles) with general relativity (gravity) to create a cohesive theory that explains things consistently from the very small to the very large (i.e. particles to stars).
There are commonalities in the problems faced by all reasonable current theories:
Experimental evidence is hard to come by at the "extremes". Singularities/black holes/event horizons/etc. are a mess.
Heisenberg uncertainty suggests we cannot know a particle's gravitation field.
From my understanding, string theory contains a plausible candidate for the graviton and an explanation for the relative diminished strength of gravity contrasted with the other forces.
So, are you asking what the most advanced and speculative theory on gravity is, or are you asking what has been experimentally tested and verified?
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