What is gravity?

[Nesti (Mark)]

Originally Posted by xelasnave

How are the tragectories of our space craft calculated? What math is used Is Newtonian sufficient or do they use GR?
alex

Absolutely! Newtonian gravity can calculate a spacecraft voyage across billions of kilometers and through a 100m x 100m window. Add relativistic considerations, and it can be much better...the true on-board [relative] time can also be calculated...which is important.

I believe it depends upon what the application is as to whether they use one or the other. Don't forget, GR is calculation intensive.

[xelasnave]

Mark said
For me, everything, every effect must be attributed to a cause, there is no independent self fulfilling system; everything must pertain to a common purpose or central reality.
All phenomena link together in a mutually conditioning network
Buddha, 500BC
Is this the first TOE..???
anyways a Universe that recognises the aether and takes its interaction with matter into account has a chance of sucsess...
alex

[xelasnave]

Originally Posted by Nesti

Absolutely! Newtonian gravity can calculate a spacecraft voyage across billions of kilometers and through a 100m x 100m window. Add relativistic considerations, and it can be much better...the true on-board [relative] time can also be calculated...which is important.

I believe it depends upon what the application is as to whether they use one or the other. Don't forget, GR is calculation intensive.

Thank you, thank you thank you...may be old hat to you but stuff like this takes me a long ways forward in understanding stuff.
May I ask then to be specific..in respect to the prediction NASA made re the Pioneer..was their prediction based upon Newtonian or GR calculations.
alex

[sjastro]

Originally Posted by xelasnave

How are the tragectories of our space craft calculated? What math is used Is Newtonian sufficient or do they use GR?
alex

You don't use GR. For low velocities and low gravity fields, Newtonian physics is used.

In fact for trajectories involving gravitational slingshots, Newtonian physics has it all over GR.

Regards

Steven

[shane.mcneil]

Originally Posted by sjastro

"What is gravity" is actually a philosophical or metaphysical question.
Science struggles with "what is" questions. "How" questions are easier to answer.

A person of religious disposition would argue that God created gravity, a philosopher might answer that gravity is part of our consciousness.

Steven

Well to be honest, this thread went over my head several pages ago. Although I asked the question, I didn't expect it to be such an involved or debated subject. It wasn't meant as a philosophical question. Perhaps I should have asked, "How does gravity work?" I'd been reading some books on gravity and it wasn't clear to me if GR was the generally accepted description of gravity (and thus geometric) or if Quantum Physics covered it (and thus the graviton). I see now why the books weren't so clear. No one seems sure.

However, I believe that everything has a "mechanism", including gravity. Even if there is a God who created gravity, it still has to work some how. Or if it is a result of our consciousness, again it works some how. That's why I love science. It tells us how things work. The individual can then ponder, Why?

I think we will work it out one day. I just hope I can understand the explanation.

Regards,

Shane

[Nesti (Mark)]

Originally Posted by xelasnave

Mark said
For me, everything, every effect must be attributed to a cause, there is no independent self fulfilling system; everything must pertain to a common purpose or central reality.
All phenomena link together in a mutually conditioning network
Buddha, 500BC
Is this the first TOE..???
anyways a Universe that recognises the aether and takes its interaction with matter into account has a chance of sucsess...
alex

Google 'Jainism', and have a hunt around for Jainst Cosmology...I bet the level of intelligence 3000 years ago knocks your socks off.

Their TOE must encapsulate everything, including one's soul and Karma.

[Nesti (Mark)]

Originally Posted by xelasnave

Thank you, thank you thank you...may be old hat to you but stuff like this takes me a long ways forward in understanding stuff.
May I ask then to be specific..in respect to the prediction NASA made re the Pioneer..was their prediction based upon Newtonian or GR calculations.
alex

I wasn't aware that NASA were discussing the issue...are they???

[xelasnave]

Shane you can not post anything about gravity without a major responce because grav ity is the most interesting topic any human can discuss...
Gravity is the machine that runs the Universe and although specialisation takes our eye off the ball that will be found to be the fact.
I do believe humans have madee a fundamentally incorrect assumption and that is that a force of attraction exists when it does not...yet in an attempt to fit the Universe into human understaqnding attraction is the only tool they seek to use... yet it is clear at a higher level it is not attraction that controls things..even dark matter will prove unworkable..my math tells me that and would tell anyone the same if they reasoned so... but gravity is it..everything comes back to it in my universe it is all the forces in my view... manifested in different forms but all gravity nevertheless...and gravity is no more than the flow of everything creating an infinite energy flow that "runs" everything... can I prove that ..no... it is an opinion based on an overall observation of everything and how it may fit with everything else...in my view gravity is a pressure of everything coming from everywhere... and there is no way one could support such with math as it must be far too complex.

alex

[shane.mcneil]

Thanks Alex. And maybe you are right?? That's why I think science should never be certain that they know it all, because it creates blind spots. Many a thing has been taught in a science class room that was later proved to be wrong. So that's why I try and keep an open mind. What I was wanting to do was understand what the current, generally accepted view of gravity is.

As to the Pioneer craft. Are you talking about how they are slowing down unexpectedly and no one can explain why?

Shane

[xelasnave]

Originally Posted by Nesti

I wasn't aware that NASA were discussing the issue...are they???

Before the Pioneer left the heliosphere they (NASA) expected certain things I expected other things..My expectations were based on a belief that space was "sticky" as a result of my thinking re push gravity...now my thoughts are simple, crude and unsupported but I expect that for NASA to think the Pioneer would do different to my expectations they may just have used math..they do that and I bet their predictions had a math base... and so I ask... for them to consider what the Pioneer would do when they passed thru the barrier that seperates our solar system from "outter space" did they use Newtonian or GR physics? They must have worked out something and I ask how did they work out their view... sorry to be verbose to get to such a small point... and I already expect that they used Newtoian from what you have said so far... but I doubt that GR would have predicted slowing either.
alex

[Enchilada]

Originally Posted by xelasnave

Before the Pioneer left the heliosphere they (NASA) expected certain things I expected other things..My expectations were based on a belief that space was "sticky" as a result of my thinking re push gravity...now my thoughts are simple, crude and unsupported but I expect that for NASA to think the Pioneer would do different to my expectations they may just have used math..they do that and I bet their predictions had a math base... and so I ask... for them to consider what the Pioneer would do when they passed thru the barrier that seperates our solar system from "outter space" did they use Newtonian or GR physics? They must have worked out something and I ask how did they work out their view... sorry to be verbose to get to such a small point... and I already expect that they used Newtoian from what you have said so far... but I doubt that GR would have predicted slowing either.
alex

Good point. It is complicated, but the differences between them is very small - and in especially testing theoretical explanations for the real cause of the anomaly. I.e. It could have been influenced by another gravitational force by an unknown gravitation body. I..e. An asteroid, etc. My thanks for asking what seems as genuine question, Alex.

[xelasnave]

Originally Posted by shane.mcneil

Thanks Alex. And maybe you are right?? That's why I think science should never be certain that they know it all, because it creates blind spots. Many a thing has been taught in a science class room that was later proved to be wrong. So that's why I try and keep an open mind. What I was wanting to do was understand what the current, generally accepted view of gravity is.

As to the Pioneer craft. Are you talking about how they are slowing down unexpectedly and no one can explain why?

Shane

Of course I am right Shane my major authority is that I am always right
Before the Pioneer left our Solar System there was room for consideration and in my case speculation..
For years I followed investigation of gravity and concluded we knew little as to its machinery etc...so I considered how the Pioneer would act in a push Universe... once out of our Solar Sysrtem I believed they would be subject to more "push" in effect and as such must slow..also that their atomic piles if they had any would expire faster..I dont know how or if they have atomic stuff in fact but if they did my view would suggest different to the expectations...anyways they slowed as I thought they would..now that means zip as all sorts of things could be responsible for them slowing but as you can appreciate the fact that they did made me feel as if I was on the money...and so I humbly say I can explain why they slow and the fact that they did really makes me think I could be correct in my view of how the Universe works...now no one will ever know how the Universe works but you probably can understand it gave me some hope that my view of the Universe was more correct than possibly the current view.
I really feel that attraction is a myth and that is so hard to believe..as we see attraction all over but I see all attraction as a mere push misinterpreted... dark energy if it is there suggests that Dr A had some foundation in his cosmological constant....or as I like to call it "push"... push works for me and although at odds with all science that is accepted I "see" universe governed by a push mechanism.
It makes things simple..no dark matter for a start... a simpler explanation for how an atomic bomb works, how electricity works, how magnatism works,..in fact hbow everything works..I see it but no one else can and so I diddle along with feelings and hopes but no math in support of my views...and thats cool ..the neat thing is no money is at stake so what the heck..its a view..an idea... simple..not a big deal.
But it is what I think about and fit everything else into...
alex

[shane.mcneil]

I remember reading some other suggestions about the pioneer craft. One was a gas leak and some others I can't remember, other than as has been said, an unknown body affecting them?

As far as a push universe goes, I would have thought that if that were so the universe would look very different. An object would be pushed away from something until it became close enough to something else and then it would be pushed away from that. It would be like a cosmic pinball machine wouldn't it? Can you describe a curve or an orbit in a push universe?

Shane

[xelasnave]

Enchilada said ....could really take apart some of the ridiculous nonsense stated here - but really who has the time in an amateur forum like this one.
Mate dont get upset it is not that big a deal.

A simple truth must be able to be stated simply..now Dr A said similar but I dont have his specific quote to that effect..Firstly how could one embrace the complexity of the Universe here or anywhere..a lifetime is horribly too short..may I remind you the most wonderful minds humans have put forward, Dr A, Hawking Witten Newton etc (how could one make a comprehensive list and be credible really) still have not grasped all of it or even a small part of it... so it remains that all humans are entited to speculate, to have a view and to believe what they may..who cares if some are wrong.... why look down and say anyone is wrong..what is the point in that..do you think I am really serious when I post.. this is a forum where all folks get to have a go ..most do not project their "real" knowledge because it is a forum after all.......I am only serious if there is money or life involved other wise its a game...as it can be and should be...

Gravity is still the biggest question hanging over humans,,, and if anyone has the answer why dont they come forward..if you think GR or Newtonian physics is the whole deal I suggest you could think further because the fact remains humans know zip about gravity and the rest of the Universe...

As you go thru life you finally realise diffderent folk have diffent views and finally there is no absolute truth..if you say there is then time will put you in the box tagged "idiot"... Nothing is constant or permantly "real"..all there is finally is folks views on stuff...If you want to back everything our science tells us is fact today you are doomed to a humiliating review by folk in the future... as difficult as it is to comprehend we are not at the point where we know everything..now that may not rest easy but take a couple of years to consider what I say before you fix your position on all things...science evolves and will continue to evolve and to fail to recognise that sees one condemded to stupidity and you are well above that I feel.

alex

[xelasnave]

Originally Posted by shane.mcneil

I remember reading some other suggestions about the pioneer craft. One was a gas leak and some others I can't remember, other than as has been said, an unknown body affecting them?

As far as a push universe goes, I would have thought that if that were so the universe would look very different. An object would be pushed away from something until it became close enough to something else and then it would be pushed away from that. It would be like a cosmic pinball machine wouldn't it? Can you describe a curve or an orbit in a push universe?

Shane

To understand everything start where there is nothing.
Ask what may be there and how it may effect stuff..it is that simple.

If it works by push it will be like a pressure "from everywhere".

Anyways I have tried to communicate my ideas and present my observations upon this and it really boils down to ...you see it or you dont.. I see things different to others I conclude..and I am not trying to be different or stand out for non conformity it the way I "see" things.. I visualise maybe to a higher level that other folk so what I see is easy ... but make other brains "hurt"..others see via math or via illustration etc..I see things perhaps in a complexity that makes it difficult to desciobe... I really try to be like the others and talk as simple as I can to communicate ..that has most folk thinking I am stupid..and thats ok...I have nothing to prove other than I am not a geek anymore.
alex

[xelasnave]

Anyways settle down folks..
are we all not interested in similar things...no one has to stand over anyone else... everything is finally a belief..even our best science is a belief... we believe because we have "the facts" but as humans we grow and learn more facts and as we get more facts our views modify..but it matters not who thinks what here I would like to think... we are all interested in the Universe..can we not rejoice in that...

Male humans are prone to seek domination over other male humans...that is the way of it...but that is a legacy from our animal days.. we are now better..we are now able to live and let live... if you are right or wrong puts no food on your table so nothing is important unless you rank your ego as worthy of prominance in your being.
alex

[xelasnave]

Page 8 ...are we closer to an answer..or closer to a recognition that we know zip about gravity other than being able to move space craft with confidence.... a higher level must be available to us if we recognise we are the past for someone elses future.
alex

[AlexN]

Closer to the recognition that we know zip I would think Alex..

I am sure there is an answer to the question, but whether or not mankind will find this answer in my lifetime.. Thats another question all together. The problem I see is that people hold onto science history so tightly that they lose the ability to consider different options and different approaches to the question... GR was not fully accepted from day one, simply because people held onto Newtonian gravity for so long that the thought of something as radical as GR was hard to come to terms with..

Einstein didn't like the idea of QM at all, even after lengthy debates with plank and bohr, he still did not want a bar of it.. Why? Because it did not always agree with GR, and GR is how he'd come to understand the universe...

[michaellxv (Michael)]

Originally Posted by avandonk

If we know so little about gravity Alex, how did those ignorant twits at NASA fly their probe through the Cassini division?

How did anyone prior to Newton know how to aim a projectile?
We don't have to fully understand something to use it.

I have a couple of theories.

Firstly dark matter/energy are just a place holder that kinda make the maths work for what we see. A bit like calling sqroot(-1) = i - when no such real number exists.

Next, the spacetime continuim is such that all times and places co-exist. Our conciousness just moves from one state to the next (should fit with quantum theory I reckon). Dark matter/energy is just all of that matter and engery which exist at times which are not now hence we cannot see it. All of this should make time travel possible when we do work it all out

Unlike 400 years ago we at least acknowledge that we do not know everything. If you look at the increasing rate at which scientific discovery builds on previous work it should only take one more generation to work it out.


Michael

[AlexN]

Michael, I agree completely with regards to dark matter/dark energy being placeholders to make the current mathematics work/suit what we have observed... And that what we observe is dependant on our state in spacetime.