Space Time and Gravity

[xelasnave]

I am fascinated by gravity and enjoy my own unusual ideas as some of you who know me :hi: already know.:screwy: :whistle:
The concept of space time seems to me to provide a geometric explanation of gravity and I think I must be missing something and ask does anyone have a concept of how gravity actually works..that is how does one object communicate with another its "being there" (without using the rubber sheet and the bowling ball explanation if possible).
alex

[sheeny]

Good question Alex!

The only other concept I've heard about other than the rubber sheet analogy is the graviton particle theory. In practice they are probably the same... at least until experiment can distinguish one from the other, and see which one is closer to reality.

I'm not sure that I'm particularly up to date on gravitational theory or particle physics, but I believe the graviton is predicted by one or more theories but hasn't been detected:shrug: . Is that right?

...of course there's always the old faithful "Gravity sucks" theory!:D

Al.

[AGarvin]

Hi fellas,

There is really only one viable theory of gravity and that's Einsteins General Theory of Relativity, which says that space curves in the presence of mass. The greater the mass, the greater the curvature. The "ball on rubber sheet" analogy is a sometimes confusing way it illustrate this concept.

Also, one of the underlying concepts of GR is the principle of equivalence, that is, being in a gravitation field, such as standing on the surface of the earth, is equivalent to uniform acceleration. Based on this, gravity is like rolling down a hill of space. The greater the mass, the steeper the hill gets the closer you get to the "bottom" (ie, the source) and the faster you go.

The idea of the graviton comes from Quantum Mechanics. In QM, everything has to be quantised. Just as the photon is a quanta of electromagnetic radiation and the gluon is a quanta of the strong nuclear force, so to gravity must be quantised. Under this theory, gravity would be the exchange of gravitons between masses.

Unfortunately, the mathematics of both theories fall apart trying to explain this, GR at small scales around the Planck length, and QM just all over.

Cheers,
Andrew.

[xelasnave]

Thank you very much for your interest and input. I like the sound of the QM approach as I guess it is this physical interaction that I am trying to nail down. It is how the messages are conveyed by the not yet found particles I find interesting. I can not get my head around the "mass curves space concept" and it is not for the want of trying.
alex

[robagar]

um, the GR equivalence principle states that gravity is indistinguishable from acceleration.

I don't like the bowling ball on the rubber sheet thing either. Apart from the fact that the emphasis is on the third dimension (ie down) when it's supposed to be a 2D model, it also appears to rely on gravity itself to to pull the marble or whatever in towards the bowling ball.

Not that I have any better way of visualising curvature of 4D spacetime I'm afraid :-/

[AGarvin]

Indeed I should have chosen my words more accurately and have corrected my original post accordingly. What I should have said was non-inertial motion. Why I simply didn't say acceleration ....

[sheeny]

Alex,

An interesting book to read is "The Elegant Universe" - it's also available as a DVD (I have both). It tries to cover a lot of the GR / QM unification work that is being attempted by string and brane theory in layman's terms. I'll post more details if interested when I get home and have access to the book.

Like all attempts to explain extreme physics/maths in layman's terms it has to make assumptions about what the reader/viewer knows and also some approximations to simplify concepts, but I think it does a reasonable job. There are holes in the explanation where I don't understand things, and there are other bits that, for me, are a bit over simplified, but on the whole it's not bad.

Al.

[robagar]

btw, yesterday was the 87th anniversary of the first observation of gravitational deflection of starlight by Arthur Eddington, the first experimental evidence for curved spacetime

[josh]

Gravity is one of the signs that the universe is putting the breaks on after the bang.It wants to put itself back together again.
Perhaps it will all be drawn back together and squished after all.

[xelasnave]

Thank you all for your interest. My curiosity is how the gravity message gets from one object to another. I have notions that "star light" provides a universal radiation pressure, a pushing force which is observed as an attraction between objects. My thoughts are gravity results from an imbalance in the pressure caused by one object shielding another from the "universal pressure". Without formulea or experimental observation and prediction my idea in simply an idea. But how it really works (if different to my idea:D ) I would like to understand.:shrug: what "things" travel between stuff to trigger gravity.
alex

[Starcrazzy]

hmmm...don't know about that...any "pressure sheilding "would surely accumulate at the fringes of galaxies and indeed the universe causing areas of Less pressure and therefore less gravity..And also your theroy doesn't account for the vector of gravity..the direction in which the force acts..Like the out of the box thinkin but...There are some that believe gravity leaks into other dimensions which is why its such a weak force (compared to the other 3) which would give us a way of communicating between dimensions..There are serious attempts underway to capture a "gravity Particle"..As far as i know they have yet succeded..

[xelasnave]

Believe me if we got to chat I can answer all:D;)
alex

[Starcrazzy]

exellent...would love to hear it mate...i have had an ongoing umm, lets call it a debate, with a really really clever bloke..its been going on for about 3 years..we are debateing the age of the earth, of the universe for that matter...He is a YOUNG EARTHER...he believes the bible tells the real creation story, and puts the age of the earth at around 5000 years...an easy thingg to disprove i hear you say...well...this guy keeps the argument going by putting the science that i use into question...i say things like, carbon dateing, the decaying of beta particles of certain atoms over time...he will say stuff like, yea, but that method would need a constant level of radioactive particles in the environment over the entire time...aarrrgghhh....its been going on fer years...we both love the challenge...so...don't be afraid to post a long post explaining your theory...i have found that in trying to explain something to someone else often helps clear it up for myself aswlell...does that make any sence??

[xelasnave]

Dont encourage him or you wont get rid of him:whistle: .... have you ever followed those instructions?:) I pursued my ideas on astronomydaily.com (black hole forum) and I feel that my work to date in the area entitles me to the title of crackpot.:screwy:
I simply feel that the ideas about gravity does little to explain its workings and with the current approach needing dark matter to make everything work I felt the world needed direction ..so hence my input.;)
I fancied that the number of photons and minute particles (dust nature) and atomic particles may be enough to form a pressure.. I call it gravity rain to demonstrate how we would be pressed to the surface by the inflow of stuff...it comes from the other side of the planet also but the pressure from that side reduced because of the presence of the planet. If you think about it at any point and every point there is there will be particles from every point of the Universe passing thru it at C at every direction, from every direction, from everywhere... I feel there would exist a resultant pressure. In true Morosophic fashion I can fit anything into this idea, optics and momentum are easilty explained:D
There is plenty to sink it but I use it in an effort to find someone who can explain in a nuts and bolts fashion how gravity works:shrug: ... so far my idea is the only "nuts" and bolts model I can find.:lol:
alex

[Starcrazzy]

exellent...love it...have yopu heard of the casimir effect??
if ya havn't..google it..u will love it...it sort of fits with your theory and is a well documented and experimentally proven effect relating to the zero point energy of the universe, which is from my understanding, what your sort of prodding at...I however have a problem with this line of thought...because einstein's energy matter equivilance formula's dictate that energy as well as matter would cause a warp in fabric of space time..and if there is all this zero point energy and it is in the abundance that they say it is, well then the universe would be looped back in on itself...sort of like a massive black hole??not sure if thats the exact way to put it, but there it is...my problem ina nuts and bolts fasion(well nearly)..Basically a cosmic "pressure" in my humble opinion, wpould cause major problems with the warping of spacetime...
Ps, i could be wrong but isn't the universe's expansion accelerating at the fringes??Even all the theoretical dark matter can't seem to put the brake on??dunno...what do ya think??:shrug:

[xelasnave]

Yes I know of the effect.
As to space time what are we talking about here, after all my looking into it, I find space time is described as ..similar to a pythagras theorum (to demomstrate lenght depth and high) with a "negative" time line. I am not sure that it exists in th ereal world an is little more than a math description of an unreal world that never the les can be described and measured by "space time".. the curvature seems to me a decription of how to calculate distance taking into account c.. I would like to hear a description of how matter warps space time... the rubber sheet seems to me to use the very thing (gravity ) it seeks to describe as if it were irrelevant and un noticed in the role play.
I see no reason to find a physical looping back of the Universe upon itself if such pressure were found to be more significant than currently thought. That is a dictate of the math known to this point however I think there is always an implication that there can always be more to the story. I mean I am only trying to describe how all the Universe works in complete contadiction to current cosmology so there will be a few loose ends. However as far as the gravity idea goes I say this. If you open your mind to the proposition it makes sense ..My system gets rid of the necessity of dark matter and would explain why locally galaxies are being pushed together yet at a ceratin distance the Universal pressure is able to act so as to force them apart. I recon the Cosmological Constant may have been an attempt to describe the pushing force (I predict) however Eienstein had to drop it when Hubble came out with "facts"... his observations of galxy recession. I wonder how he may have developed the idea if timing had been different. Radiation pressure is considered now although only somwhat locally in Super Nova ( and after) situations. However radiation is not insignifficant.. recently 20% more of some kind was found to exsist which to me underlined the imporance of this form of energy within the Universe.
When pushed to determine the edge of the Universe few will say there is one, however there is nothing beyond the Universe..so we have something without sides top or bottom..limitless. However if there is nothing on the outside or indeed no outside I ask into what is the Universe expanding, a difficult problem as there is nothing beyond our Universe (so they say). Space does no exsist for a billion light years and then we get to a fence on the other side of which we find..nothing?? cant happen. I have difficulty with the Observations that lead us to see the Universe as Expanding as the question to my mind is "if it is expanding..to where does it expand?" "Into what". There can be no such thing as "nothing" only "space" which covers all over so where can it expand to?? Now we need some fast talking to get past that point.
As to where we may find the fringe of the Universe I dont know. Last I heard was the Universe is 160 billion light years across a distance covered in 13 billion light years..yet at 160 billion light years as a chosen dimention is it expanding into billions of light years of "nothing".
The current explanations call upon some difficult propositions so the difficult proposition I ask one to consider as to the possible opperation of gravity in the manner I present.. in that context I feel it is not that outrageous..
I can see no begining or end to space and feel what ever perception we may have that space is expanding may be wrong, we may be witnessing nothing more than a local "eddy" past which things are different and reveal the Universe as we cant see it.
alex
alex

[Starcrazzy]

Ok..ok..im hitting the hey now, iwill postulate a retort (lol) as i slip into slumber..But a quick note before i go, a good example of matter warping space can be found in the experiments with distant stars being acculted by large masses such as planets, other stars, galaxies and of course, your old friend,,,the black hole..or do you mean to say that the pressure wave is what causes the difraction??in a sort of particle capture mechanism??hmmmm...no sleep for me tonight...
cheers
ps..have you read hawkings latest book...the universe in a nutshell??you probably have, but if not, i will loan you my copy...you'll get a kick out of it

[xelasnave]

Think of the pressure from all directions caused by stuff travelling at c as light passes an object Sun, Black Hole or Galaxy such object sheilds the "particles" with the result that the greater presence of particles from the "exposed" side.. the light is accordingly pushed to the area of less pressure (gravity effect). Now I know Dr Eienstein has an idea on this also so you have the rubber sheet is doing it or the "particle" pressure is doing it. It is called an Aristotleian approach but hey I dont make decisions that affect anyone so what the heck. Mmmm book on the Universe I was going to write one but what the heck I could read one instead. Thanks.
Steven Hawkins approach to the Universe is similar to the Pope.. both models have a beggining and an end one model took 7 days for initial creation and the other model 300,000 years one model says the clock has run for 13.5 billion years and the other model says it has run for 6000 years. Personally I recon if we find there is a God behind all this there would be no start or finish which is very mortal in conception, for if it is not this way we will have to look for where "he/she/it/all" grew up.
alex
alex

[Starcrazzy]

oh yea..im startin to smell what ya cookin...with it coming from all directions that would explain why the effects are uniform on both sides of a planet and so forth hey??very clever..ok..so it seems in order to see if the theory hold up i reckon we need to reverse the time line back to some time after the big bang...around the time when light started to shine..so we would have an incrdeibally dence and hot region full with this immense "pressure" from particles hitting eachother at c..now..it is known that the effects of Gravity weren't strong enough to contain the outward expansion of all these particles..if your theory wwere correct then all particles in this dense soup wopuld have anearly infinate sheilding from all the other particles causeinfg an infinate force of "g"..OR..the partcles would not be sheilded enough because of the massive amounts of "c" travelling particles which would cause the early universe to expand out in a puff and not allow thwe gradual concraction of matter to form thwe stuff we love looking at so much...im not sure which one (if either) would be correct...but whatever the mechanism of gravity, it wasn't strong enough in the early universe to contain all the partlcles after the big bang, and for a pressure sheilding situation surely the pressure in this eraly stage would have been ginormous....dunno...but its great fun ..:thumbsup:
ps..as for the age of the universe thing....don't get me start6ed...lol....

[xelasnave]

I find it understandable that humans must have "a start" and not to have one seems beyond comprehension, however I say why not.:D
We all except almost without question that it is possible for the "seed" of the Universe to appear from nowhere in "nothing" and in that nothing created "space" and without further input of energy or matter or any other thing being added from "outside" , and thereupon to expand at an inconceivably rate which would see its "edges" if it had them travelling at many times the speed of light (if there was anything we could relate the speed to that is and of course there isnt???)...To me, after many years of seeing the wisdom in the theory, when it is put as I have done so above, and it be a fair statement generally, I dont think a Universe without a begining is any stranger than the current view that all there is can fit on the head of a pin at T plus .000000001 secs after "ignition". It is a long time ago so who knows really what happened how it happened (let alone why it happened if it took place that way). I know what they know but I recall steady state was the rock solid view maybe 30 years ago for many scientists... oh the olden days when we were savages? my point is the world was once flat and it took a crack pot to point out the misconception and also why those of high intelligence were fooled by the "view" of their then "observable Universe".
I liked your thoughts to fit it into the big bang plan. You certainly seem to grasp what I am trying to convey. Think about gravity lensing to get the idea quickly.
AND a qualification.. although I am seriously interested in "everything" and perhaps more in "nothing" (and the implications of the difference between nothing and "space") and above all gravity, at my age I dont give my soul to any stand.. things change new things get discovered etc ..but I enjoy a chat
Thanks for your interest and input.
alex

[xelasnave]

If you are bored I have had a bit to say elsewhere but here is a "simple" statement I made to start it off there.. dont read all of it just the first post.
http://forums.astronomydaily.com/viewtopic.php?t=4364&postdays=0&postorder=asc&start=0
alex

[Starcrazzy]

exellent...no problem...Yes, i think we are on a similar page when it comes to the current parradigm of the cosmos, thats why i will entertain the idea of the earth being younger then 5000 years( i may not believe the theory, ) but i will entertain the idea, and certainly don't take any FACT for granted..It is crackpots that change paradigms, and intellectual discussion and debate can only serve to aid the crackpots in there articualtion and continuation of there proposed idea's..I love your energy pressure/gravity theory, and have enjoyed the p[laces it has taken my mind..lol...sometimes it only takes a simple statement to start the mind boggling and bouncing through some crazzy and whacky ideas..I too don't see a need for a day 1..that's not to say the evidance doesn't point to one, but i see no need for timeline to start anywhere or end anywhere...i would be more leaning towards a loop, or a circle, perhaps the big bang was the result of a big crunch, the big coming together of all the matter in the universe under its gravity and reaching a critical energy matter singularity and resulting in a massive explosion, and in time it may all happen again??mabye its happend countless times in the past and will keep happening exactly the same way in the future...we know nothing can be made or destroyed, only changed....:shrug: I will end with this bold statement...matter can not exist without time...my real passion is in the understanding of time and how it works..
chhers alex

[xelasnave]

Just as I find contemplating a "start" hard to accept an end is more difficult. Consider the implication of a big crunch.. the most distant photon is is wizzing thru space (almost reached "the fence between nothing and space";) ) when the message arrives, big crunch time..does the photon slow to a walking pace, stop and finally start a return to the object it came from?? I doubt it personally and that would be an easy solution:) . Where are the sides in the big crunch? Does the fence between nothing and space remain in place or does nothing gather around whilst the Universe colapses to the size of a "mustard seed":shrug: . When you analyse nothing and its importance and necessity for some of these propositions to get up I think you may manage any suggestion as to what will go on inside the Universe but when it has become but a seed what will we call the stuff around it, can logic allow it to exsist even in speculation?
Time works one of two ways usually against us and usually it wins.:lol:

alex

[xelasnave]

At the risk sounding foolish,I have been reading yet more about this (space time, gravity gravitons etc etc) and ask is not "space time" a geometric expression? The key issue as far as gravity seems to be that it removes the requirement of force between objects and explains gravity as bodies following the course of the least resistence provided by space being curved near objects. I see no reason why radiation pressure could not indeed be the physical way objects affect each other and space time a system of geometry to "measure" and "quantify";).The problem of making special relativity fit with quantum mechanics leaves the graviton in the same boat really as "gravity" rain. String theory seems to support the exsistence of a graviton.. and I add I have no idea about string theory and am simply relating a snippet from my reading.
The graviton "they" look for comes from the quantum approach and they talk about it as "interacting" with other particles. It is discrete (not secretive but a "seperate" particle) with a spin 2 and I dont understand that but it implies its ability to interact with other discrete particles I gather. It seems to me whatever quantum mechanics comes up with it will have difficulty fitting SR be it my gravity rain idea or the graviton they seek. I dont know if there are any experiments looking for the graviton. The cleaning fliud tanks in mine shafts look for dark matter candidates as I understand it..wimps in particular... gravity rain would be very wimpish I recon.:lol: :lol: :lol:
alex
They dont say it acts as a pushing force yet but they are almost there:D
alex

[wraithe]

hmm, i think i need to do some more reading about what you wrote...dont dispair, my problem is that i'm doing 3 things at once and to read that and do the washing at the same can be a little confusing...cant put gravity in the washing machine and i cant put washing powder in the pc...
Love the theory, brings on a whole new way of looking at things, yet a way that has been there and dismissed...be persistent and people with little ideas like that, will slowly be accepted...most nutters turn out to be true thinkers but the "not so intelligent" do like to flex there muscles and not there brains...
by bringing force into the equation instead of attraction, you have shown another way of explaining the forces of the universe...i do have a problem with time, i see it as a constant and all other things being variables...and the big bang..hmmm...i think some one came up with that after seeing what happens to stars after they implode...the idea that the universe can be measured by us is absurd(dictionary plz)...yes maybe it did happen a few trillion times but we have no way of saying that the universes is expanding, only our little section we can measure..how big is the universe?..well i try not to think of it as i have this idea that it dont end, to base religious beliefs into that then it has an end but to accept it is endless is hard for some...(they may say it but not think it)...
if force is the constant within the universe then most of our theories are wrong(they probably are anyway)...attract and repell are the opposites of each other and can be confused with each other..its the same with electricity...if you have down any welding with an arc welder, you will see the molten metal flow away from the welding rod, but at the same time the welding rod is being attracted to the metal...now some say its the electricity force you away but it also attracts...now when a welder arcs it has a cycling effect caused by alternating current...thats two opposites, one attracting other repelling...in the universe, what is the attracting force and what is the repelling force, is it possible that both exist and we have only looked at one with the wrong idea of which one we are looking at...

anyway back to my washing...
Kath

[Doug]

G'day, if I might add a few thoughts on the debate?
Universal preasure, coming from all directions? wouldn't that balance out to zero? Take for example an object sealed in a chamber. The chamber would equalib equi eqk... balance out the forces leaving the contents of the chamber at virtual zero G, if I am understanding the idea.
The rubber sheet idea is far too simplistic to have any real value, but I wonder if 'we' threw out the baby with the bath water, when the idea of an ether was discarded? (No I don't believe in a flat Earth,... too many hills:rolleyes: )

Consider the effects of 'surface tension' on objects floating on a fluid, if there were a sort of etheral medium in which the physical universe was boyant then that would also give rise to universal attraction; provide a medium by rule of the density of which the limiting velocity is C, would be in harmony with relativity etc, etc.
The big problem I guess is that the physical universe doesn't lend itself to the idea of laying on a sheet; rubber or etheral.

cheers,
Doug

[Doug]

Dr. Russel Humphreys Ph.D., a physysist has published a paper and subsequently a book titled 'Starlight and Time'. From memory he presented a concept that more or less agreed with relativity, however he shows a model whereby the universe can be young, yet the distances for Galaxies is still valid.
A book well worth reading. One of the concepts he uses, reminds me of an ether. He wouldn't / didn't use that expression either because his work would be dismissed out of hand, or perhaps I have misunderstood what he meant. In any event he does raise the possibility of a something, not dark matter, but a something.
cheers,
Doug

[xelasnave]

Thank you Kath and Doug for your interest and input.
One can think as the pressure come from everywhere it must achieve an equilibrium however the "stuff" making up this pressure is traveling at C movements of bodies will constantly be mixing the contents of the barrel.. as the Moon travels across the sky it is pushing thru this pressure and now doubt the constant change prevents an equalibrium being achieved.
And remember that the coming from everywhere thing literally applies everywhere ..that is hard to comprehend.. Think of what stars you see at a particular place and mental move to others you see the same stars..they each castenrgy to each and every part of the Universe they touch. Look at one of my wide field shots, each star,each point of light is the centre of a many layered sphere of light extending out to space for billions of light years (ok so there are young stars as well) and as full of stars as those shots display the number of stars in the Universe number many billions fold. Yet at anypoint light from each object passes thru the selectedl point .. and perhaps an underlying "pressure" a "gravity rain" that falls everywhere in creation.I one were to sample the light travelling thru the sparsest part of space, it will contain a sample of all photons from every where.. (some will not have reached that point but I hope you can see the picture in its enormity and complexity from trying to mental put all this in a box...just think of the objects billions of years old whose light has passed that point for billions of years)
Thanks again
alex

[xelasnave]

I could not find this earlier but can you see why I like it;)

Michio Kaku: "Einstein also said that behind every great theory there is a simple physical picture that even lay people can understand. In fact, he said, if a theory does not have a simple underlying picture, then the theory is probably worthless. The important thing is the physical picture; math is nothing but bookkeeping."
:thumbsup:
alex

[g__day]

You have a number of competing theories for this one, from SuSy to super gravity to relativity. We can not answer for sure is gravity quantised yet (dip into Loop Quantum Gravity vs the Higgs Field and Higgs Bosun). We are pretty sure that Gravity can radiate in any Realtivistically dominated volume of spacetime within 97% - 100% of the speed of light (based on the theory of relativity and experiements in 2003 involving quasars and Jupiter. But we don't yet have a framework for gravity that works well at extremes of interstellar distances (just look at MOND) or microscopic distances (for that matter none of the four forces work sensibly at these down to quantum levels.

Under GR spacetime itself can expand faster than lightspeed without voilating any rules. Because its the framework or topology of spacetime, not the matter nor the energy within it, doing the streching. In laymans terms outside or between two gravitationally held volumes of space (where relativity definitely applies) say the rather large and empty void of spacetime between two super clusters, spacetime itself can expand at, equal or above lightspeed without violating General Relativity.

Too GR and its rules break down in any of the following situations:

1. Quantum level - as you approach a Planck level of space, time or distance - you are ruled by quantum mechanics not relativity, which follows a totally different and wierd set of rules

2. The really energetic places - once you the heat to the level where energy densities approach 10^15 GeV (think above 10 ^ 24 Kelvin - much, much hotter than a super nova) you are getting into the realms of the heirarchy problem. At this point the fours forces (gravity, electromagnetism, strong nuclear and weak nuclear forces) are predicted to re-combine one by one (like a backwards Big Bang cycle) until you have three, then two and finally only quantum gravity remains to control such a reality. Once strong, weak and electomagnetism merge you are nowhere near the domain of GR and the rules of gravity can be kissed away.

3. Extremely dense objects, think grav stars and black holes, again within their event horizon scenario 2 above may play. Outside the event horizon gravity is certainly the dominant force and relativity again holds sway.

The Higgs field interacting on the Higgs bosun is an interesting model, show that gravity is really just a side effect of a deeper underlying reality.

Finally here's an interesting aside for you. If all the matter and energy of the Universe was once again localised you'd have a black hole with an event horizon how big? Well about 20% bigger than the best estimate for the volume spacetime is believed to occupy today! So how did the big bang every manage to outrace its own crushing gravitational shell - that should have imploded it back into oblivion before it got past a trillionith, trillionith, trillionith of a second?

Answer - likely gravity didn't exist as a seperate force until the Universe had cooled and expanded and inflation finished - at around 10^-34 seconds after the big bang. Prior to that quantum gravity held sway. Once inflation kicked in the Universe was travelling maybe 50,000 times faster than lightspeed until it had expanded form a point in space up to the size of a orange. By this stage it cooled enough for gravity to phase into dominance. But the Universe by this stage had become casually disconnected into clumps (Hubble Spheres) expanding away from each other faster than lightspeed. So gravity could not travel from one lump to the next fast enough for the expanding peices of the Universe to catch the fleeing pieces and pull it all back together!

To this day our reality is our Hubble Sphere - a light cone 14.8 +/- 0.1 billion light years, in a Universe that may exceed 200 billion light years diammeter. Beyond this distance things are too far away and receding too faster to every influence us under GR. Perhaps this is what Dark Energy really is, our reality passing where other Hubble Spheres have come and gone and their residual gravity wells expanding our Universe!

[Shawn]

OOOh Alex this is so close to "time dilation" next it will be haircuts and sport...:P

[Shawn]

In fact, you could get away with it if you argued, Whilst I was getting a haircut, watching Sky on the hanging TV on the wall which was tuned to a football match , I had a revalation.."insert post" very subtle but you could probably get away with it.

[xelasnave]

G Day
thank you for your input and interest.
You have been more informative with very useful information in a small parcel. Of course when you see gravity as a pushing thing there is no reason to see a problem of the Universe crushing as you wondered. If it was this way the radiation pressure in effect is the gravity pressure. Its only an idea but I am trying to explain how gravity rain makes points like this managable.(at least in my mind) this way of seeing it makes it easy to see why when close things will get "pushed" closer but when they are gravitationally remote will be pushed apart by the overal pressure. Just a thought.
alex
alex

[g__day]

Alex my pleasure

Head over to the Astronomy and Astro Physics section of www.advancedphysics.org (http://www.advancedphysics.org) and you'll be able to ask questions of many folk studing for their PhDs in the field, its an excellent website I fully recommend. You could also try www.able2know.com (http://www.able2know.com) but that's amateur hour outside of physcology compared to the avdancedphysics site.

[xelasnave]

Thanks for those links. I doubt if you realise what you have done letting me loose. I have had a quick look and they both interest me and it seems like the sort of thought I enjoy is practiced (not off beat just trying with legitimate tools) I will learn much by reading the various attempted explanations and different things will click and fit, so that is so very positive. Thank you.
alex

[xelasnave]

Whilst on the subject I have been thinking about how my view of gravity may work in deep space. With our space craft leaving the Solar System they will encounter “deep space” something understood to be empty and devoid of immediate and significant gravitational influences. I read that they are slowing down in one account and in another that they were speeding up.So before I will look to see what they are doing I thought it through to see if I can predict what we will observe as they deal with “deep space”. Contrary to what others expect (I expect) I believe that we will see the craft appear to stop and then accellerate away to reach a speed of (same as Sun) after some time they will appear stop and then return in our direction.
This should show space is pushing I have a lengthy explanation if anyone cant work out why it will do that:) .. but a space time explanation tells you the same will happen. I think so on my simple attempts to understand the implications:shrug: . Space time does not really show a push or a pull in fairness but if nothing else it says that an object at rest will want to stay at rest and that an object moving relative to deep space will wish to become stationary in relation to deep space. Or such is what I take from my understanding to date.
It is as much a prediction as to the effect of space time on objects in deep space as it is a gravity rain prediction commenting on the same. Gravity rain from all directions as it will be in deep space (and space time the rain is in the direction of the mass:D ) means I think that deep space will hold objects not subject to a considerable gravitational influence.
I suspect that when craft enter deep space they will be stepping out of the solar system bubble of influence and become their own separate bubble, and as such governed by the events of deep space not of the events within the solar system. When stuck in space the speed of craft will become that of our Sun simply by being stationary in relation to deep space. Eventually the Sun will show a corridoor of less gravitational pressure and the craft will start back. this will appear to us that it is slowing not returning however.
. Imagine an island in a lagoon at the edge of the lagoon and all around the water and the island is a small sea wall, such that the wall forms a circle all around the island and its laggon. When one stands on the wall you can look and see the island in the centre of lagoon and that the whole is enclosed in the sea wall ..on the other side of the wall is an ocean not joined in any way to the island other than the water that laps the outside of the wall. Looking to the outside ocean you notice that it rushes past at considerable speed although iots surface is smooth and unruffled as you would not expect given the apparent rush of water past your view, it is rushing faster than you could paddle your canoe in the lagoon. You drag your canoe out of the laggoon and over the wall and set it in the ocean, as soon as you push off from the sea wall you are carried away from your island sea wall at considerable speed.. you stop paddling but the island still rushes away . The surface you find yourself upon is calm not showing any evidence of the speed you noticed when your island was close.. even birds float about ..it is as calm as you have experienced in your Lagoon.. but you know your island travels thru this Ocean as if it had a destiny elsewhere (and it must).
I see similar when the space craft leave the influence of the Sun and solar system. Our system is like a bubble in deep space. The barrier where the Solar wind hits "deep space" may be where we find this sea wall between our island and lagoon, the Solar System, and the out side ocean of deep space..
When space craft get into deep space they will appear to race away from the Sun because of the Sun's speed relative to deep space in a similar fashion to the canoe racing away from the island. And although out of the expected range of gravitational effect if there be no other body present to confuse my outcome the Sun will still provide the only "shielding" or gravitation , the next major star is 5/6 light years away so I doubt if any space craft will get close to be taken within that stars gravitational bubble. So it is expected by me that the craft will return. If in the canoe we let out a line attached to our sea wall we could eventually pull ourselves back and although weak the only gravity (shield) presumably will remain the Sun and this is where the craft must return unless they find another.
When the craft returns to Earth (assuming it has no renetry problems at the wall of the Solar System which may be a consideration ) they can "date" materials on board to see if time dilation is real or imagined and given the time before the return there will be more than nano seconds to work with and that will settle the matter even for the layman suspicious of small numbers.. so if I wait long enough that should show the pushing thing at least I expect... and maybe that time dilation does or does not happen in real terms.. all that and its not even my mission:D .
alex

[xelasnave]

and I am finding the sites to be excellent, in so far as there are many matters disussed that are of interest to me. Also they are a bright and well educated bunch on my observation, some are gruff but markedly reserved given some of the questions that appear.
Thanks again
alex