h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

You appear to be thinking of Gravity as a thing. Something that 'lassos' (is that how you spell it) and object and pulls it. However is it not true that all forces (Gravity,electromagnetism etc.) are just the effect of higher dimensions. Massive bodies 'sit' in space-time and warp it, the more massive the body the greater the warping. A more massive body also exerts a greater gravitational field. It seems that these two are linked.

Each body in space wants to move in a straight line. When they enter into another bodies magnetic field they cannot and so they orbit, if its velocity is not great enough. It cannot leave its gravitaional field and cannot 'climb' out of the depression. This indicates that the Earth, for example, is not being pulled towards the sun, but rather it is falling, but its velocity is great enough to stop it and keep it in orbit.

This points towards the fact that gravity does not have a speed because it is not travelling from body to body and pulling them.

Nice explantion of orbit, but surely "falling" means by definition "being pulled towards something due to its gravitational attraction"?

Any force must propagate from source to target, even the force that causes space to warp in the first place, and the speed of propagation cannot be infinite.

Anyway, it seems that someone has now done an experiment that (chooses words carefully) lends considerable weight to the argument that gravity propagates at the speed of light:

http://www.newscientist.com/news/news.jsp?id=ns99993232

Despite this convo being barren for a year now, i wish to continue it. As many theories and conclusions get put forward in the realms of H2G2, fundemental physics is forgotten.

1.Without mass, there is no gravity

2. An apple 200 meters away from another apple in space, will not travel towars each other at the same speed as two white dwarfs.

So, in conclusion, the speed of gravity is irrelevant, because its measurement is only determined by what it attracts. Thus, it would take matter of infinate mass to attract another piece of mass towrds it at the speed of light.

I personnally believe that gravity travels faster than light, it is not restricted to relativity of light speed travel. It is a force, it has no matter, it has no restrictions, it is a side effect of mass, that has no determinable speed. Now it can be said that from this, you could determine that magnetic fields of mere apples could strech throughout the entire universe in an instant, as it travels at massive speeds and never stops. It would seem that as a force, gravity is restricted by energy, so...Gravity travels, but it is weak, as we defy gravity simply by standing up. However...how come the gravitational force of a black hole, escapes the black hole???

You "believe"? Well, you may believe in philosophy which is two doors down the corridor ...

Also, I'm not entirely sure that apples have magnetic fields, but if they did, I'm certain that their sphere of influence would be limited to light speed.

1. You have used no scientific ...anything to back up what you said

". I didnt nessasaryily measn magnetic field...unless it was an iron apple...then... but i mean its gravitational field. I was just saying that gravity is only present when there is mass. So, the speed of gravity is irrelevant, because it is only determined by the amount of mass present.
So - Infinite mass = Infinite gravity = Light speed travel for the mass attracted to it.

This is the only way matter will travel by gravity at light speeds. Concordantly, ive said it before and i'll say it again, who cares. The only reason to care about gravity is if the earth suddenly becomes hollow.
There im done

You say that the speed of light is irrelevant. But it's not, beacuse you can send information via gravitational forces. It would be an awkward means of communication, but possible. The General Theory of Relativity (GTR) limits the speed of information to the speed of light.

So, putting the speed of gravity in question means to scrap GTR.

Cefpret, your talking shit.
1. Information could not be sent by gravity. unless the gravity was carrying a medium for the information to travel e.g light rays...radio, gamma...which can only go at the speed of light.

2. What distance are you talking about? As ive said before, you would have to fingd a way of harnessing massive gravity and concentrating it, making sure nothing gets in its way. So....this is impossible as massive energy and gravity is needed, so again.... it is impossible thus pointless

This is like saying that light produced by the sun goes faster than light produced by a candle because the sun is a more powerful source. The amount of mass in a body will determine the acceleration it gives a smaller mass and thus ultimately their relative speeds, but gravity itself will propagate at exactly the same speed.

Anything that exerts an influence on something else at a distance transmits information. It is the speed of information that is limited, thus the speed of gravity must also be limited. The engineering problems involved in harnessing gravity as a communications medium are a different subject entirely.

And why is the speed of gravity irrelevant? It may be irrelevant to everyday life on Earth, but you could say the same about the big bang, black holes, most of astrophysics and astronomy in general and probably evolution as well. Some people would like to know.

When you move a mass this can be remotely detected, without using light or particles. Just by detecting the change in the gravitational force. So you can transmit information via gravity indeed.

I suppose yes, what im saying is that in everyday life, the speed of gravity is irrelevant.
Howevr gravity behaves like nothing else, we cannot even prove its substantial existance, except from its effects on other bodies. (Many scientists debate the possibility of gravitons) However, becasue of the way it acts like no other electromagnetic wav and seemingly has no matter, that is why i claim that its speed can surpass relativistic limits. Howevr, to use gravity to our advantage in space travel is impossible, as e=mc2 etc...blah blah blah
On the subject of using it to send information...why? 1. We cannot travel near light speed, concordantly, there is no need to harness gravity to communicate with ourselves as we can use phones, and in this cirumstance light and radio is more convienient. However, to communicate with alien races, we may be able to communicate with much vaster areas of space much more quickly, that could be an advantage.

So you think that the General Theory of Relativity is wrong?

No, where id i claim that? If i think that gravity is faster than light, then yes...but what im saying is that because of the state of gravity, it concords to einstiens theory. How can something with no mass defy einstien. As ive said before, i blieve that gravity is a side effect of mas in 4 dimensional space.
However what puzzles me is that gravity can be interpretted as energy, so it must have mass if E=mc2 is correct!!??!!??

Gravity is one form of energy. This is not my statement, but Einstein's.

The *information* that a certain mass is at a certain position propagates with the speed of light, and with it the effect of gravity.

if gravity travels at the speed of light and light can't escape from the event horizon of black holes then surely neither can gravity? Which would imply that objects outside black holes arent affected by them?

hi im new here but as it seems to me this conversation seems to be talking about gravity as an object, rather than as an effect caused by the presence of mass which itself can as i see it have no speed.
when we talk of the speed of light we are talking of the EM force yes?
according to The Standard Model, the four fundamental forces electromagnetic strong nuclear weak nuclear and gravity. are manifestations of "carrier" particles(See feynmanns QED for theory), the photon for the EM force, light it is this carrier particle that has speed this is what we speak of when we say the "Speed of light".The standard model suggests the carrier for gravitational force is the graviton although it is possible that if you were to single out a real graviton how could you measure its speed?
with refence to using gravity as a carrier for message. if you had two infinatley large masses an infinate distance apart then set 1 travelling towards the other it would reach its maximum speed the instant it reached the other mass and its speed would be the speed of light because of special relativity.

>if gravity travels at the speed of light and light can't escape from >the event horizon of black holes then surely neither can gravity? Which >would imply that objects outside black holes arent affected by them?
unless gravity does not travel
i dont think that makes sense how however i look at it i just keep going around in circles.
no mass can escape a black hole as the escape velocity is larger than c

In order for that to work you have to assume that gravity has mass, which isnt proven. Also you use the speed of infinate mass over infinate space, but what is the speed of the 'gravitons' being projected from each mass... how long for instance if you put no forces upon the two masses would it take for them to become attracted? Is it instantaneous?

Also the implication that gravity cannot escape an event horizon just may not work :
1) Things are attracted to black holes
2) If your theory is right its probably due to the massive mass around the event horizon, but then that would make no sence either?
So as you said it is circles.

Does gravity warp spacetime or warped spacetime give rise to gravity?

Is gravity due to a spacetime density gradient?

The move to the lower spacetime level produces the force of gravity (and may give rise to a quantum theory of gravity).

This would also account for inertia, it takes energy to change a bodies 'at rest' spacetime frame.

It also negates the graviton/blackhole paradox as the warping of spacetime around the blackhole gives rise to gravity not the other way round.

It also accounts for gravity due to acceleration, the warping of spacetime from the change in velocity, gives rise to gravity in the vector of acceleration

hmmm... well, if the big bang theory is correct, then all matter that exists has already had a chance to act upon all other matter. given that all matter has a common point of origin, then all matter has already interacted with all other matter. one could view gravity AS the fabric of the universe. close to the trampoline example, but in multiple dimensions. more like a balloon without being hollow.it's expanding, but gravity is, and has been since the dawn of time trying to put a stop to that. if you look at it this way, gravity doesn't have to travel, because gravity IS the medium being traveled through.

right, but when you pack a helluva lot of matter into a really small space, the "shape" of the gravity changes. The force/radius curve is, from my understanding, really quite steep for a black hole (really strong gravity really close, but weak far out, as compared to, say, the original star from which the black hole "gnurps" (as it doesnt spring from a star, much the opposite of that))

so with chaos theory affecting everything, moving things about, and black holes coming and going, gravity isn't a static fabric, but rather a dynamic force.

plus, there is no medium of the universe, no ether. This theory was disagreed with by einstein, and later disproved when einstein was proved. What i mean is, the speed of light in a vacuum, c, is the same for all observers.