What is the propagational velocity of gravity?  Don't dare cop out by saying it's the same as that of light!!!
451792
We don't yet have any reliable measurement. One widely held assumption is that it is the same as \n.. Doh! .. I can't say that.
779931
The speed of light in a vacuum is exactly 299,792,458 meters per second (fixed by definition). Although some people speak of the "velocity of light", the word velocity is usually reserved for vector quantities, which have a direction.\n\n\nNothing has a speed greater than the speed of light.\n(except in Science Fiction stories)
598835
Newton's gravitational constant (G) hasn't changed one bit because of Relativity (and is in fact one of only two constants in GR the other being the cosmological constant (Λ) which was thought to be zero but is now known not to be).\n\nThough I don't think there would be any meaning of a ratio between G and Λ
468084
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
727746
Well we have\n\nwavelength = h/momentum = h/mv = h/m(.0131c)\n\nwhere h is plank's constant and c is speed of light.\nso substitute and calculate.
883279
light has constant speed... a big zero acceleration....\nlight does not have mass so no inertia... but amazingly has momentum...........
470012
A couple of years ago there was a study that said that the speed of light is not a constant. I need to look it up and see if I can find it. Now I'm wondering what the reason was behind that claim.\n\nYep, I found it:\nhttp://www.newscientist.com/article.ns?id=dn6092
125809
The struggle here is that you provide too little information to recognize this problem as coherent.\n\nWe may assume that the acceleration of gravity is 9.8 m/s/s or 32 ft/sec/sec.\n\nThe velocity(V) of an object is equal to its initial velocity(v) plus its acceleration(a) times time(t). \nV = v + at or V = v - 32t (in feet per second)\n\nYour object will reach maximum height when the velocity is zero or when the initial velocity is equal to 32 ft/sec/sec * time. With your list of times, you'd just multiply by 32 to solve for the initial velocity, if that is what the problem is actually looking for. There are many other permutations of this data, but hopefully that is a start for you.\n\nGood luck.
566668
No object that has mass can be accelerated to move at the speed of light. If you were somehow moving at 0.99c and then shown a flashlight, the velocity of the photons would not be 1.99c, it would just be c. The speed of light is invariant. The true formula at relativistic speeds is the following:\n\nV = (v+u) / (1 + vu/c²)\n\nWhen the velocites are not relativistic (i.e. throwing a ball out of a moving car) this approximates to V = v+u. So if you are moving toward something that is emitting photons at c, and you yourself are somehow also moving at c, the velocity you observe the photons to be moving is still just c. Try it in the formula: V = (c+c) / (1 + cc/c²) = c\n\nIt can be derived from special relativity or the Lorentz transformations.
120276
The first thing you have to understand is that the speed of light in a vaccum is constant, no matter how fast you're moving, nor how fast the source of the light is moving. This is bizarre. If someone standing on a conver tosses a ball to you at 5 mph while you're standing on the corner, you'll see the speed of the ball as being 5 mph relative to you. But if you're driving at 15 mph and they throw it at you at 5 mph, the speed of the ball relative to you will be 20 mph. This is how most things work. But with light, no matter the speed of the source or yourself, you'll always measure the speed of light as being 299,792,458 metres per second.\n\nEinstein accounted for this by postulating his special theory of relativity, which says basically that the reason for this is because if you move really fast, three things happen: 1) time slows down, 2) mass increases, and 3) length in directions parallel to the direction of movement contract. If you take those three hypotheses, you'll also note that the concept of things being "simulatanous" is a relative term, meaning two observers moving at the same velocity (or moving at no speed relative to one another) will agree on which events are simultaneous and which are not. However, observers at different velocities will have different concepts of what is and isn't simulataneous--and yet THEY'RE BOTH CORRECT. It's pretty mind-blowing, but if you take all of these notions together, you get a consistent view of reality.\n\nThat's Einstien's SPecial Theory of Relativity. About a decade later he formed his far more complicated general theory of relativity.\n\nThe general theory says that Newton's view that gravity operates by exerting a force on a falling object is incorrect. Rather, by general relativty, a free-falling object that is in a vacuum has no forces acting on it at all. The movement of falling objects isn't due to force, but rather the curvature of space-time--massive objects actually curve the surrounding universe. In Newtonian physics, we regard there being three spacial dimensions (up/down, left/right, and backwards/forwards) and a single dimension of time. In general relativity, there are four dimensions of space-time. In Newtonian physics, a foce makes the earth orbit around the sun. In general relativity, the earth and the sun curve the surrounding space-time continuum, and both bodies move in a straight line through curved space, resulting in the perceived sense that one body is circling about the other. In Newtonian physics, light should not bend to gravity, because gravity affects massive bodies, and light has no mass. But in fact, light does bend around stars and such.\n\nGeneral relativity has been likened to a stretched sheet of elastic material, like a trampoline. Heavier objects sink more, and make the sheet curve about them, and light obejcts rolling across are deflected by this curving.\n\nGood luck understanding all that. Hope your head doesn't explode.
1126307
the opposite of the speed of light :)
11066
well first, read my other answer to your question about the speed of sound.  You would probably expect the answer to be the same, and the light to reach the other car, but this is a special circumstance because nothing can travel faster than the speed of light, not even light itself.  when a beam of light is shone ahead of a rapidly moving space vehicle, and is expected to be moving at the speed of light plus the speed of the vehicle, it is still only moving at the speed of light, which is puzzling.  Physicists have defined the speed of light to be the ultimate cutoff point for speed.\n\nAnd also, you wouldn't be able to travel at the speed of light anyway because time would probably stop since it does get slower and slower the faster you go.  Velocity warps time, the faster you go, the slower time moves for you relative to a stationary object.  I've read this, and it is definately true, we had to derive the formula in physics from, and calculate the time, lenghth(which decreases with speed), and mass (which increases with speed) distortion as well.  The effects of this are very negligable unless you are moving at speeds very very close to the speed of light, at least over 90% of the speed of light, and we haven't gotten anywhere close yet.  The denominator of this factor that time, length, and mass are distorted by actually is 1 minus the square root of the speed of light(c) over the speed in which the object is traveling (v), so the reason you can't go faster than the speed of light is because if v was greater than c, then that square root would be greater than one, meaning the denominator would be negative, meaning the factor would be negative, and the light would actually be travelling backwards in time...\n\nIf you find any of this interesting, I highly recommend "The Elegant Universe" by Brian Greene.
478673
Looks like a controversy here....but no, gravity does not travel faster than light, it would take eight minutes before the earth's orbit changed.\n\n(If gravity was instantaneous, then it would be possible to use that to send messages faster than light!)
452909
Believe it or not, we already have it and use it everyday. I want to answer this in detail, but I cant disclose the true nature of how light travels until I publish.\nI will say that light that is propagated within a closed system can and does move at superluminal speeds relative to a location outside the closed system.\n\nI know-Everybody has a theory, but I can also explain why light bends at every instance without once referring to the fabric of space/time.\n\nWhat if Einstein was WRONG...errr...ok... (just so I dont offend anyone) not completely correct? What if light actually didnt travel by propelling itself into the electromagnetic field created by....itself? What if there was no such thing as a pure vacuum with zero atomic content? (by the way, there is no such vacuum.)\nResearch it, its true, there are always atoms left over to fill the space left by the vacated ones.\nDon't you find that at least a little interesting?  No such thing as a pure vacuum?
630475
Theory of Relativity- Light is the one speed that does remain constant.
919170
The theory is that gravity, or magnetism, moves at a certain speed.  The last I heard, that speed is still unknown but under study.  Thus, if the sun disappeared the earth would remain in orbit at the "speed of gravity"  and it would remain daylight at the "speed of Light."   Which speed is greater is yet to be determined.  However, my guess is that the speed of light is faster than the speed of magnetism.
144613
light rays do not move faster or slower than the speed of light.  the speed of light is the speed of light, period.\n\nthat said, light often travels *slower* than c, which is a constant defined as the speed of light IN A VACUUM, approximately 3x10^8 m/s.  here is a way you can actually observe some honest-to-god light traveling slower than c:\n\nstep 1.  find a window.\nstep 2.  look at it.\n\ncongratulations, you have observed light traveling slower than c.  in ANY medium (air, glass, water - you name it) the speed of light is slower than the speed of light in a vacuum.  \n\nin fact, the so-called index of refraction (n, which equals 1.4 for glass) is defined as the ratio of c to the speed of light in that material.  generally, denser materials have a higher index of refraction, and people have been able to make light go REALLY slow by making some very dense materials.  all of this is perfectly consistent with general relativity.\n\nas for FASTER than c:  under certain conditions, it is possible to make photons with a "phase velocity" that is greater than c.  however, when people speak of the speed of light, they usually refer to the "group velocity".  the distinction between phase velocity and group velocity is kind of technical; but phase velocity refers to the speed at which the individual phase fronts propagate through space.  \n\nit is possible to make these phase fronts go faster than c; but because the energy or information or whatever carried by the light travels at the group velocity, the actual speed (as far as stuff like general relativity is concerned) is still less than c.\n\nanyway, all of these results are entirely consistent with general relativity.  in fact, i don't know of any published results of a scientific experiment which are not consistent with GR.  \n\nthe fact that einstein's theory, largely concocted out of the blue from basic principles and logical reasoning, has stood the test of time for so many years is a testament to the genius of the man's work.\n\nhere are some links to learn about phase velocity, group velocity and the speed of light:\nhttp://en.wikipedia.org/wiki/Group_velocity\nhttp://physicsweb.org/articles/news/4/7/8/1