My Theory for How Gravity Works
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The "simple" model is that gravity is not actually a force (although it's effects can be treated like one in Newtonian physics).
Instead, mass distorts spacetime; the more mass, the more bending.
This is the bit that plaits most peoples' minds: objects move in straight lines through spacetime, but because mass has distorted the spacetime, the straight lines are actually bent, so (to those animals that only evolved to see three dimensions of spacetime and live along the fourth, they appear to move in curves such as the arc of a thrown ball or the orbit of a Moon.
For the problems you're solving, I'll bet that most of the time the central force you're considering is from a string, or maybe friction on car tires, or some such thing. Gravity is one particular example of a central force. It has the interesting added complication that it's not a fixed, constant force, but depends upon the distance from the center (1/r2).
Kelsymh?
The late John Archibald Wheeler (co-author of ''Gravitation'', the textbook heavy enough to collapse into a black hole) wrote, "Matter tells space how to bend; space tells matter how to move."
Trajectories in GR are curved, not straight: they have non-zero second derivative along the metric-element (ds) direction. Technically, they are called "geodesics" and are the paths of minimum or maximum distance through the curved spacetime. In particular, they are curved in the full four-dimensional spacetime, not just in the three-dimensional spatial slices of a particular rest frame.
A more familar example of geodesics (and the reason for the name!) involve minimum distance paths on the surface of the Earth. To get from point A to point B on the surface of a sphere in the shortest time (shortest distance at constant velocity) you want to follow a Great Circle trajectory. This path is the intersection of the plane defined by points A, B, and the center of the sphere, with the surface of the sphere.
The Great Circle path is curved in the "flat" three-dimensional space containing the sphere, but it is also curved in the frame of the spherical surface itself. Except for the special cases of travel along the Equator or directly North or South, any great circle route involves a constantly varying compass heading, and is therefore "curved" in the canonical East x North coordinate system.
Guess where I'm I'm going to start passing all the physics questions on to?
. He certainly doesn't have the tenacity of Kiteman. It appears to me that he's already given up on Ibles' Head YEC, Darth Gecko Man. ROFL
YEC? In any event, apart from whatever beliefs he or anyone else has, he appears to me to be a troll looking to argue.
. At first I thought he was trolling. Then I thought he really believed what he was saying and had just been misled. Now I think he's just clueless. He seems to be quite proud of his self-imposed ignorance. :(
. "Refusing to attempt to understand, willful ignorance, that is as near as my worldview can get to 'sin' as I'd care to go." - Kiteman
As for DGM, I'm waiting for him to actually respond to my last two leaf nodes in that thread (my third question leading to descent with modification, and the trivial logical deduction of selection from observable facts of nature). If he's unwilling to continue the discussion himself, there's not much I can or should do about it. Silence speaks for itself.
...social networking jargon...
Worse, it's in American! Actually, I think you're going to fit right in, Science-wise, and you make stuff. Give it another couple of weeks, nobody will realise you're new.
If nothing else, Plasmana should have added his own projects!
Starting from the field equations, you can take the limit of weak gravity (or equivalently, nearly flat spacetime) and derive mathematical analogues to Maxwell's equations. This has inspired any number of crackpots to suppose that EM and gravity are "equivalent".
Lets take black holes for example. In the space surrounding the event horizon of a black hole the extreme gravitational effects make time appear to flow more slowly than is usualy the case.
Let us set up an hypothetical NASA mission to explore the edge of a black hole. Lets say that we have two astronauts, Astronaut A and Astronaut B. And lets imagine that Astronaut A flies his spaceship to within one mile of the event horizon while Astronaut B takes up a positon about 1000 miles away from it.
Now, the extreme gravitaional pull would try to suck anything and everything (including light) into the black hole. This would mean that the light bouncing off Astronaut A would travel AWAY from the black hole at a much slower rate than normal, while the light bouncing off Astronaut B would travel TOWARDS the black hole at a much faster rate.
This would mean that, to Astronaut B, his companion would appear to be moving in slow motion, while Astronaut A would think his friend was living at hyperspeed. Even though each astronauts "individual" experience of time would be unaffected.
This proves (I hope lol) that the idea that time rules light is actually the other way round. The speed of light determines the speed of time, and thats why time is said to be relative.
I hope that makes some kind of sense
On a side note, your happy GPS system would be off by several kilometers if the software didn't take into account both the special- and general-relativistic corrections necessary to convert the time signals from each satellite into your frame of reference on the Earth.
... when I was a graduate student, my officemate said something that we put up on the board, and it stayed there for at least five years:
Life is a sucking, swirling vortex of despair.
He was British.
The magnetic dipole moment of an atom is proportional to the spin of the atom (technically, the total angular momentum of the nuclear spin, electron spins, and electrons' orbitals).
Atoms with zero spin have zero magnetic dipole moment and are consequently not magnetic.
With a sufficiently high frequency RF field, one can probe the spins of the nucleus, or of the individual electrons, rather than just the net spin of the whole atom. This is the basis of NMR (Nuclear Magnetic Resonance).
Yes, I am well aware of the difficulties with general relativity and quantum physics. According to some, string theory is the most promising solution to explaining gravity. This theory would allow for the existence of gravitrons (although I was unaware of this when I posted the original comment). Not everyone is convinced string theory is correct, even some who work on it. I do not believe myself sufficiently knowledgeable to judge its merits, but I do know there are some problems with it that may require an even more advanced theory to explain it all.
And are you going through all my comments from months ago?
You wrote, "This theory contradicts general relativity, which explains gravity as the curvature of spacetime. " First minor quibble, we don't even have a "this theory" yet -- there are many, many competing possibilities for "the theory of quantum graviity," including string theory, M theory, loop quantum gravity, causal triangulation, and more.
You also wrote, "This theory would allow for the existence of gravitrons." The mathematically rigorous (I trust the mathematicians who say this :-) statement is actually much stronger than "would allow." No matter what form "this theory" eventually turns out to take, it must include a properly quantized propagator for the gravitational interaction.
You are quite right (as you've implied) that defining a propagator for the structure of spacetime itself (rather than for a field which is embedded in a background spacetime) is difficult and laden with pitfalls and apparent contradictions. I certainly have no idea how to get there from here myself.
I read a lot of science stuff, both technical articles in Science, Nature, etc., as well as "popular" magazines like SciAm, New Scientist, etc.
NM commented below on your last point, and it's absolutely true. The reason professionals get impatient with the crackpots and apparent crackpots who thing they've discovered The Secret, is that Science is by its nature a cumulative process.
Whether you (the general "you", not AM in particular!) want to build on and expand our existing understanding, or overturn established ideas with a new paradigm, it is your absolute responsibility to know the current field, in all of its detail, and then work to go beyond that.
<soapbox>
If you don't understand the basics, then you are simply not qualified to have an opinion about whether those basics are right or wrong. It is astonishing to me that people can take this concept completely for granted when they take their car to a mechanic, but assume it doesn't apply to understanding the functioning of the universe.
</soapbox>
I've come up with an entirely new and awesome theory to describe the universe and everything in it, despite the fact that I dropped out of third grade after repeating it four times. My theory is actually similar to super string theory, only I call it the Packing Peanuts theory, because I believe all matter is made up of tiny quantum packing peanuts, which are vibrating at exactly the rate of Pi.
The scientists all laughed at me when I described it, but that is only because they are jealous and plan on stealing my theory and are afraid of me being awarded the Nobel prize first.
My main experiment for the past 12+ years has been BaBar, which finished running back in April. I'm starting to participate (we call it "collaborate") on the ATLAS detector at the LHC, while continuing data analysis and publications with BaBar.
Thanks (about the shirt)! That headshot was taken when I had a small bit on a NOVA episode a few years ago along with a Web posting. They recently replayed it, and you can see about five minutes of stuff at SLAC at the very end.
That is so cool. I've never met a particle physicist!
!
I just watched that episode of NOVA! Except I missed the last 10-15 minutes because it was like 1 in the AM. I'll have to re-watch it on the DVR...
when there's alot of "stuff" then it attracts other "stuff", and then you've got planets revolving around the sun.
the reason "stuff" attracts each other is very complicated science...
just remember: matter attracts other matter.
for a completely un-informed guess, that was pretty good. *and wrong* but still a good guess for an epiphany...
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