I heard something about gravitons, what is the current thinking?
198939
In physics, the graviton is a hypothetical elementary particle that transmits the force of gravity in most quantum gravity systems. In order to do this, one theory posits that gravitons have to be always-attractive (gravity never pushes), work over any distance (gravity is universal) and come in unlimited numbers (to provide high strengths near stars). In quantum theory, these requirements define an even-spin (spin 2 in this case) boson with a rest mass of zero.
103690
How are you still alive?\nSo, how did you come up with the gravity idea?\nDid the apple really fall on your head or is that just a stupid story?\nHow do you back up your theories if you are the first one to come up with the theory?
438219
I know of no reputable astrophyscists who claim space is empty.  In fact, Brian Greene's "Fabric of the Cosmos" spends a lot of time talking about the stringy stuff that fills space.  The Higgs Field is also a something that fills space according to some theories.  Further, mass bends space, bent space has been observed; so it seems logical that space is a something (not a nothing) that can be bent.  So your premise that space is not empty is widely accepted.\n\nAlthough there are some short-lived massless quanta that can penetrate great distances, most cannot.  And the great distances have limits.  Even neutrinos have a limit on how deep they can penetrate a mass.  Gravity, on the other hand, is not diminished by interceding mass.  We are affected by measurable gravity in the deepest, darkest caves, for example.  So none of the known and theoretical quanta, save one, exhibit the characteristics of gravity.  \n\nThat one exception is the graviton, which is predicted by string/M theory.  The graviton has never been observed; so its existence has never been proved.\n\nSo your supposition that the effects of gravity are due to bombardments of quanta of some sort does not generally stand up to the evidence.  The one exception is the graviton, which is strictly theoretical and may not exist.
258669
if the centrifical forces are as great as you say it is. then the probablity of this force creating a dimensional vortex because of its immense gravitational energy is very probable...but how you gonna test something like this.\n\nCan I cheat and ask stephen hawkins?
250072
string theory is realy a piece of genius it came uponly since v found so many irregularities in the quantum gravity theory of einstein and others \n to no the basics u bettter read some god books onthe topic\n           i can only say that by far it is a great piece of work and only if v had better particle acc v could hav proved that the theory is correct (or wrong )\n     also rear about the m-theory if u can
134702
Gluons are the force particles of the strong nuclear force that keep the quarks together in protons and neutrons. Quarks exchange gluons between and this forces them to stick together.Compare this to a soccer team exchanging the ball between them: the players cannot be too far apart.\n\nGravitons are the force particles of gravitation. But contrary to gluons, they have not been detected.A lot of physics theory would fell apart if gravitons don't exist. \n\nGravitinos are entirely hypothetical. The arise in a theory called supersymmetry that tries to combine all four forces of nature into one.
220654
A.) In his General Theory of Relativity, Einstein developed a mathematical description of gravity—one that links space to time and mass to energy in a fundamentally geometrical fashion. In other words, mass(-energy) shapes space(-time) instead of acting like a “force” in the traditional Newtonian sense.  (Thus, in Newton’s description of gravity, one would say that all bodies exert an attractive gravitational force on one another. In Einstein’s conception, one would say that all bodies change the underlying geometry of space-time in a way that causes them to be attracted to one another.)  Thus, our best understanding of gravity is that it’s a fundamental property of space-time to be “warped” by the presence of mass(-energy). So gravity is simply a property of space-time, and most likely, it came into existence at the same time.  (One caveat: curvature or warping really only provides an analogy to what the equations tell us. If you want to imagine the effects of an object on its surrounding space-time, then you can think of it as changing the shape of space-time in its vicinity. The distortion is real—we can measure its effects—but the images that are often presented of flexible sheets of space-time with bowling balls or marbles rolling around on them, for example, simply present analogous situations.)\n\nB.)  Spinning is a common attribute of objects in the Universe because the way things form virtually always leaves them in rotation, and once things get started rotating, it’s hard to make them stop.  It’s not intuitively obvious, but if you take, say, a cloud of gas and dust collapsing to form a planetary system, then averaging all the random motions of the particles will leave you with some tiny element of rotation.  As the collapse takes place, any rotation will be magnified, so you end up with planets revolving around their parent stars, and planets themselves rotating on their axes.\n\nC.)  It’s doubtful that we’ll ever acquire much in the way of interstellar real estate, simply because the distances involved are so great.  Our best hope is to carry on radio communication with them, but even at the speed of light, it would take decades or centuries for radio signals to travel between us and the stars currently within our range of communication.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
665536
I read a book about this.  I don't remember the title, but this guy claimed he had it.  He claimed that all atoms are expanding at the same rate.  This is what causes gravity.  More massive objects expand in more space in less time than less massive objects.  \n\nI don't remember the details of the rest of the fields, but they all related to this expansion of atoms.
369316
Unknown. Without an adequate theory of quantum gravity, this object that GR predicts would be a singularity cannot be described. At quantum mechanical scales, pure General Relativity is not a realistic depcition of space-time.
642337
As mentioned in other replies, physicists don't yet have all of the "how" questions answered. Einstein, in the General Theory of Relativity, pretty much nailed the underpinnings of the current theoretical understanding of gravity. Here is my attempt at the "nutshell." I'll start with an analogy. Let's say you are driving somewhere in the midwest or plains states--essentially flat ground, with a few rolling hills. Let's say you stop your car at the top of a slight rise. As you look around you, you see flat land in every direction. You're sitting on essentially a two-dimensional plane. Taking your foot off the brake, you notice the car starting to roll forward. Your initial observation about the 2-dimensional "space" you were sitting on isn't quite accurate. The 3rd dimension (altitude) has come into play, and gravity is pulling your car into the swale. What Einstein said (and how he came up with this back in the early 1900's is incredible) was that our THREE dimensions are really a slightly inaccurate description of the world (and universe) we inhabit. A fourth dimension, time, is part of the "fabric" of our surroundings. As in the case of that slight "warp" in the 2-dimensional farmland that led to a noticeable effect on your car, Einstein said that warps in the space-time continuum are experienced as gravity. As you know, Einstein was into the "energy = mass" thing big time, and you know that mass is tied up with gravity as well. If you want to get more cozy with these related concepts, I strongly recommend David Bodanis' book, "E=mc2: A Biography of the World's Most Famous Equation" -- available as a "BooksOnTape." It's exciting, full of cool anecdotes about the heroes of 20th century physics, and... NO MATH, just concepts. Best of luck!
167775
Yes, the first part is true.  Why does that make tides more "believable"?  \n Any two gravitaionally-bound objects will orbit around a common center of gravity.  (which is closer to the more massive object).
604594
Gravity may only be a theory, but we have a good idea that it is real. We may not know the exact workings of gravity, but we know it is there.\n\nGravity affects everything. It affects all the planets, it's what makes us revolve around the sun. I'm sure the 'devil' has nothing to do with making sure all the planets get around the sun. It's trivial, and you're theory is even worse than the theory of gravity because it has absolutely no backing. We can see gravity and it's effects everyday. Scientists don't know all about it, but for the most part, we know it's real. Your theory on the other hand, there is no proof of the devil. He's a made up character, fake. Then to say he pulls us down, you forgot to take into consideration everything else effected by gravity, not just humans. \n\nIf the devil is pulling us down so effectively, he must be extremely strong. Where is your God to pull us up? Shouldn't He be able to pull us up, if He is so great? Nope, still not happening.\n\nTheory disproved. Face it, religion plays no part in science. Religion's purpose is to make people feel good about themselves, and provide answers to the answerless (such as creation). Science is out to prove what happened, and religion serves as a temporary explanation for most.
294755
I find the concept of an event horizon with a singularity behind it where spacetime curvature becomes infinite fascinating. The idea of spaghettification is intriguing (and a bit frightening!) too. And although scientists reassure us that artificial black holes would be perfectly safe, creating one seems...well, crazy. On the whole, however, I find the whole concept fascinating and wish I had time to take an advanced physics or astronomy class to learn more about it.\n\nI'm afraid I don't understand the other commentator's God reference, though. What black holes have to do with God, or at least the Christian God, is completely beyond me. Last time I checked, the Bible said nothing whatsoever about them.
263585
You do have a point. Of course Schrodinger's equation was a brilliant breakthrough but these theories necessarily have a mathematical foundation and sometimes that foundation is not as secure as generally perceived. Mathematics is evolving and some of the stuff coming out is very weird, paradoxes and all, and this ends up affecting the way scientists formulate their theories. Put it this way: most physcists are not expert mathematicians and they are often a step behind with respect to rigor. As far as quantum mechanics is concerned, one has to consider its real and significant successes as a useful theory but with the realization that any developing theory  will necessarily have growing pains and it will need to be adjusted, finetuned and sometimes overhauled in the light of new info. in order to be incorporated in a more general theory of which it is a special case much like classical mechanics had to adjust to both quantum mechanics and the special and general theories of relativity. I think the greatest revision to quantum mechanics and General relativity will occur when the large and the small, and the uncertain and the deterministic, are finally 'married' in a breakthrough theory of quantum gravity. The problem with general relativity is that it is deterministic field theory and it is based on the concept of a space-time 'continuum'. I think the concept of continuum upon which the formalism of general relativity is based, is counter-productive and it needsto be replaced with a quantized 'granular' space-time structure that would allow things to get unified. On a philosophical note, you are right, in a sense, concerning questionable foundational definitions since if you keep asking the question: and what precisely do you mean by that? It doesn't take that many questions before you are reduced to axioms which are based on presumptuous perceptions of the human mind: In otherwords we could be missing a lot.
610647
IANA Physicist, but....\n\nWe're not really sure.  The assumption that they exist is based on the fact that there isn't enough visible matter to keep the universe in the state that it's in.  That is, in order for the universe to behave in the manner that it is, there should be enough matter to generate the proper amount of gravity, but we can only see about a third(?) of the amount of matter required.  Therefore, the rest of the required gravity must be coming from matter that we can't see, hence - Dark Matter.
522903
It is scientifically possible.\n\nConsidering we do not even know what causes gravity, your experience may well be feasible due to complex aspects of gravity.\n\nWe formulate gravity by observation and assume it increases with mass of objects in proximity, and decreases dramatically as distance between objects increase !\n\nThis formulation is approximately accurate in isolation and within simple boundaries.\n\nScientists are still bewildered and shy to reveal recent discoveries that indicate most of what is around us we can not detect. Dark matter and dark energy have gravitational effect, so powerful that the current rate of expansion of universe is considered a rip - influenced by dark matter and dark energy !\n\nString theory along with dark matter and dark energy suggest a dozen or so more dimensions exist around us.\n\nSo, rather than denying unexplained phenomena, we would be better off researching them by scientific validation and verification.
211982
Greetings,\n\nKinda outta my league, but perhaps the link I posted can be of some use to you.\n\nDiscover had an article last year about a couple of inflation cosmology theorists who believed the speed of light, while constant now, was not constant in the very early universe, it was in fact slower.  Not sure about all that, but thought you might want to go digging for the article.\n\n-matt