Other sources of gravity
- Thread starter alsoknownas
- Start date
The strange thing about our understanding of gravity at the moment is the way they try to explain it.
The current model of explanation uses a sheet of rubber to represent space, and a heavy ball placed in the middle to represent the mass of a planet or star. The rubber sheet sags down in the middle where the heavy ball is. A second smaller lighter ball is introduced representing a moon of a planet or a planet in a solar system.
They throw the second ball into the outer edge of the depression in the rubber caused by the central ball and show that it travels around the central ball in ever decreasing circles until it finally stop against it.
This model is horribly flawed. It does not explain gravity at all. In fact it uses gravity to work. Space is represented by a two dimensional sheet and the central ball only causes a depression because it is being pulled down by gravity.
However there is no up or down in space which has at least the 4 dimensions we experience and reputedly has up to 11 dimensions. It is an illustration of a completely inadequate idea.
The current model of explanation uses a sheet of rubber to represent space, and a heavy ball placed in the middle to represent the mass of a planet or star. The rubber sheet sags down in the middle where the heavy ball is. A second smaller lighter ball is introduced representing a moon of a planet or a planet in a solar system.
They throw the second ball into the outer edge of the depression in the rubber caused by the central ball and show that it travels around the central ball in ever decreasing circles until it finally stop against it.
This model is horribly flawed. It does not explain gravity at all. In fact it uses gravity to work. Space is represented by a two dimensional sheet and the central ball only causes a depression because it is being pulled down by gravity.
However there is no up or down in space which has at least the 4 dimensions we experience and reputedly has up to 11 dimensions. It is an illustration of a completely inadequate idea.
Bob_the_lost
Elsewhere
Gravitons.
Thing is the force is so weak they have to be really really weak individually, which means hard to detect.
Signal 11
also programmed for conversational english
It is not a model or an explanation of how gravity works. It is an analogy.
Sunray
Its sunny somewhere.
Note : At > sub atomic sizes.
onemonkey
winmonkey
the Higgs boson is sort of a gravity particle... it is the particle which gives everything weight... this is completely different from a graviton which is the hypothetical particle exchanged in gravitatonal interactions but don't ask me how or why..
i mention this because the Large Hadron Collider which has just been switched on in CERN may discover the Higgs Boson within the next year or so..
http://www.guardian.co.uk/science/2008/apr/08/particlephysics.starsgalaxiesandplanets
golightly
Actively uneconomic
Doesn't the Higgs Boson give particles mass rather than weight? I know I'm being a tad pedantic, but the distinction is important.
Yep the Higgs Boson is proposed to give particles inertial mass as opposed to gravitational mass. The distinction is importnat because it doesn't provide a mechansim for gravity. There's got to be soem connection somewhere thoguh because observationally (and by the postulates of GR) inertial mass and gravitonal mass are equivalent.
FridgeMagnet
Administrator
I recall asking my A-level physics teacher this sort of question. (I used to get thanks from other people in the class for asking questions like "does a bullet have enough energy in it to melt itself?" and "so, how does gravity work? I mean really work" in double physics, because it meant they could get essays finished for the next period.)
Anyway, he must have twigged that time because he said "the current theory is that it's the exchange of virtual gravitons" in a way that had the subtext "go on, I dare you to find a way to ask about that which doesn't blatantly look like you're trying to distract me from what this lesson's supposed to be about". Stamping on a child's scientific curiosity, bah, disgraceful.
Anyway, he must have twigged that time because he said "the current theory is that it's the exchange of virtual gravitons" in a way that had the subtext "go on, I dare you to find a way to ask about that which doesn't blatantly look like you're trying to distract me from what this lesson's supposed to be about". Stamping on a child's scientific curiosity, bah, disgraceful.
YOu sould of asked him "What about the renormalization problem?"
FridgeMagnet
Administrator
I'd best time-travel back a few years and let myself know....
Sunray
Its sunny somewhere.
Well, thats the thing, they are not.
Newtons model is an approximation. The moon for instance isn't where Newtons model of gravity says it should be. Its close, but 10m out is 10m out and in maths it means Newton was a very clever bloke but ultimately wrong.
It was all detailed on that interesting Horizon on Gravity the other week. Slightly annoying bloke, but interesting documentary.
The equiavalence of inertial and gravitonal mass is assumed in Newton's universal gravitation, but it's not a central plank of the theory.
In Einstein's general relativity the equiavlence is a central plank of the theory, you just can't get it to work without it. This is 'cos in order for free falling objects worldlines to be geodesic paths in spacetime, objects moving locally at the same velcoites must follow the same paths. This is only possible if their gravitational mass and their inertial mass are proportional.
electric.avenue
lots of work to be done
Yes, this has been done. It requires really sensitive equipment to detect any force at all with objects of such low mass. It's only cos the earth is so bloody huge that we feel the gravity that keeps us on it. Gravity is a mysteriously weak force compared to the other three, (weak interaction, strong interaction and electromagnetism).
Wait while they get the Large Hadron Collider going at CERN - then they might even discover the Higgs boson which supposedly gives things their mass, and accounts for all this gravity milarkey.
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