Challenge: Is there a max. distance gravity can propogate?

I agree. Assuming gravity is propagated by gravitions: At a distance of a few miles from the electron there are often zero gravitions within a mile for your detector to detect, even if one electron emits a 10^34 gravitons per century at the speed of light. How long are you willing to wait for your detector to detect one graviton and how can you be sure it came from the electron, instead of from something 10^40 times more massive many light years away? Neil

Unless there is a smaller carrier of energy that we have yet to detect or even theorise (a possibility of unknown likihood) basically I guess you have a probalistically small chance of feeling any gravitational influence.

So at large distances from small sources of low mass you'd have to use a probablistic approach to would you experience a gravity wave - is my guess!

So what you're taught at school or University - that all matter attracts all other matter - is a bit of an over simplification.

But an object the size of a star emits more gravitons, so the distance at which you would be reduced to noticably intermittent gravitons might be quite large. I'm sure our basic description of the phenomenon is correct, but it's not very useful if we don't know how far a given sized mass propagates enough gravitons to make their influx seem continuous. Practically speaking, even if the influx of gravitons from a star is still fairly continuous at a distance of a few light years, the gravitational effect will still be so tiny as to be of little interest.

The real question is what is gravity? We don't really know. We know what it does but not what it is.

Gravitons are just a theory - they have never been detected in any experiment. There is slightly more evidence that gravity is due to particles interacting with both Higgs bosons and the Higgs field than due to gravitons. CERN though they detected a Higgs Boson at 119GeV just a few months ago.

To my recollection Physics still teaches that a Gravity field extends indefinitely from any and every source of mass or energy. I ponder how this is true if its energy falls below the minimum known energy carrier.

It depends on two things; mass and speed of rotation.

Probably the universe is not so large (as gravity totally vanishes).

Yeah........... from my little bit of reading on the subject I thought that gravity keeps going forever. You shoudl be able to detect the gravity of an electron at 6 billion light years. Apparently nothing stops gravity. *shrugs*

Scientists know we have a long way to go before we understand gravity.

Hmmm.. I'd say there is only one thing - the sensitivity of the device being used to do the measuring.

fishin' You're probably right; I'm just spewing stuff I have very little knowledge of.

Length of day and year seem to little effect gravity, as we have close up confirmation on several planets that the strength of the gravity is proportional to the square of the mass and inversely to the square of the distance. Neil

g day gday

You ask a very interesting question. I thought initially that gravity must extend infinitely. But if its quantised it can't. On the other hand no one has demonstrated gravity to be quantised as far as I know. Your question gets to the root of the problem of combining quantum theory and gravity, and the best answer gets a Nobel prize... good luck! :wink:

I think I understand the inverse square relationship from your figures.

Certainly, the gravitational pull is inversely proportional to the square of the distance between the objects.

So, you have an exponential decay in force.

Your real question seems to be - at what distance does gravity decay to an actual zero rather than an infinitessimally small amount.

I think the answer is likely to be none...at the sub-atomic level things tend to be determined by the probability of something being 1 or 0 (for the sake of argument). The probability of there being an instantaneous gravitational effect decreases until there is a smaller and smaller probability of the pull being noted...but the absolute zero point will never be reached...IMHO!

KP

I think the idea here is that a gravitational field actually amounts to radiation of exchange particles, often believed to be gravitons, from the source, and that, at some distance, you would only receive a graviton from the source, once in awhile. The gravitational effect would then amount to an occasional graviton, and you would lose the sense of being in a continuous field.

In the Graviton theory - you can ask is there a minimum energy level of a graviton and is are gravitions quantised like all other force carrier particles?

In Relativity - Gravity is the curvature or spacetime, no more or less - but space can is is quantised in Relativity down to the Planck level 10^-99 metres cubed and time appears to flow rather than be quantised, but we can't theorise events happening on a scale smaller than Plancks constant of 10 ^ -35 seconds either. So in Realitivity is there a distance F from a mass M such that the warp or curvature of spacetime is intermitent - switches on and off every few secods, days or years etc...

The Higgs Boson and Higgs field fit into both the physics of Quantum Mechanics and Relativity and are such are quantised.

So in effect I am asking is there a finite distance F from a mass M in a vaccuum such that due to the quantisation of either the curvature of spacetime or the gravity energy carrier space warps or gravity is detected as a minimal pulse only very infrequently?

Also remember a Vaccuum is proposed to be a frothing chatoic quantum sea of virtual particles and anti particles that exist for only the shortest of Planck moments. But there missing combined energy mass is one of the greatest inconsistencies of theoretical physics. Unless the virtual particles and anti particles cancel themselves out with 1 * 10 ^ -120 accuracy - a mind boggling puzzling ask - then every cubic centrimetre or space should theoretically contain 10 ^ 120 Joules of energy. Which is something we don't seem to be seeing every day!

Engineering can not detect extremely small, dilute etc, but we are extending the threshold, which is to say that which was truly negligible a few years ago, may have uses with improved technology, so I suppose we can say gravity extends to the ends of the universe, even if present technology can't detect it a trillionth that far. A possible solution is to make the detector collection area about one square light year.
Quantum theory only means there is nothing close by to detect most of the time, but eventually another quanta will arrive from even the smallest, most distant mass, which is likely easier to detect than a continuous picoplanck if there is such a thing. Neil

Taa, But this is a question more about classifying the definition of 'extends infinitely" to saying either:

1) the force carrier is not quantised and extends infinitely or

2) the force carrier is quantised so beyond the distance where the carriers value would the lowest energy state then gravity must be considered a diffuse field effect varying with time.

That last part has some interesting implications for the curvature of spacetime and also leads to more theoretical weight that gravity waves should exist and that gravity lensing should reveal gravitational difraction patterns (peaks and troughs) as gravity waves interact with each other.

To my knowledge LIGO has never detected a gravity wave nor evidence of gravitation differaction.