gravity is supposed to be distortion of space time by mass right?
but can anybody tell me WHY does mass distort space time at all?
i would like to have the 'conventional' answers or whatever is mentioned in relativity...i would love to hear ur own ideas..but pls mentions if they r so so tht i wont be confused...
i am not a relativity expert or anything but i know some about it,but i never got to read or hear anything on why exactly mass distorts space time.
i really wanna know coz this really amazin idea fer an alternate hypothesis hit me but i wanna clear some of my concepts before trying to derive it mathematically.
thanks a lot.

ecclesiastes:

It is an observed fact that if you jump out of the window, you will feel weightless. Einstein merely elevated this observation to the status of a law of nature, called the Principle of Equivalence. It says:

There is no (local) experiment you can do which will distinguish between being stationary in a gravitational field and being in a region of zero gravity with a constant acceleration.

Think about what this means. It means that if you are skydiving, then ignoring air resistance you will feel no forces. Gravity, for you, doesn't exist. On the other hand, standing still on the Earth's surface, you feel the ground pushing upwards on your feet; this is the force which causes your perception of weight, not any kind of gravitational force.

There is no problem with this provided observations are made in a small enough region of space. But if you look at large regions, funny things happen. Drop two objects on opposite sides of the Earth and they appear to move in opposite directions (both go towards the centre of the Earth). Moreover, they move towards each other. Yet according to Einstein neither one has a force on it, since gravity is not a force. So, how can we explain their relative motion?

It turns out that we are inevitably led to the idea of curved spacetime. The Earth curves the spacetime around it in such a way that on one side of the Earth it is curved in one direction and on the other side it is curved in the opposite direction. Balls dropped on either side follow the local curvature and so move towards one another. The important point is that no force is involved, and so Einstein's Equivalence Principle holds.

It also turns out that Einstein's description of gravity is much more successful than Newton's in explaining various observed phenomena, so even though it is harder to understand and formulate mathematically, the extra explanatory power makes it all worthwhile.

yeah.but what i wanted to know was why does mass(eg. earth) distort or curve space time at all? have physicists ever asked themselves that questions?
some professors like explainin distortion of space time using the waterbed analogy..if a ball is placed on a waterbed then it gets depressed n say marble in the vicinity of the depression sorta rolls into the pit...similarly earth depresses space time..but in a higher dimension fashion...arnt i right?
but the ball distorts the bed because of the pressure applied on the bed which is in turn caused by its weight which is in turn the effect of a force field(gravitational field)
and also if the ball were blaced on a wooden table there would be no distortion which means the fabric of the medium in which it is placed is important,which actually is the elasticity of the medium.
so for mass to distort space time ..there should be some background field...maybe force/energy/unknown factor...which sort of causes the 'pressure' of the mass on space time....and im also suggesting that space time has sum sort of 'elastic' factor....which may or may not be uniform..
in case its not uniform, the same mass can cause different degrees of distortion at different points of space time...which might account for sum percent of the dark matter....
and also, this 'elasticity' factor leads to the idea of a sort of layering ...because elasticity is mainly a layer phenomenon...the neutral layer n all tht jazz...n layering reminds us of quantisation..
these were just ideas which went thru my head a few days back (had high fever-had nothing better to do n increased brain activity)..
i just wanted to know if there r ideas similar to mine suggested by scientists or anywhere in the literature....i do realise that my background field could be einstein's quintessence or cosmological constant...though i wudnt bet on it...
id really like to know wht u think o this...hope u dunt include this in pseudoscience...

An important point to be made about the 'waterbed' analogy. The object is not laying on the waterbed, but rather in it's membrane. The usual illustration shows a ball rolling on a tarp, but actually the curvature is to the center of mass.

ecclesiates:

yeah.but what i wanted to know was why does mass(eg. earth) distort or curve space time at all? have physicists ever asked themselves that questions?

Believe it or not, I think I explained why mass distorts spacetime in my last post. It distorts it because otherwise gravity wouldn't work as it does.

Remember that spacetime distortion is a theory which explains observations. There may be other possible pictures which describe the effects of gravity, but I'm not aware of any description which is as useful as Einstein's curved spacetime. Does that mean spacetime really curves, or is it just a convenient way of picturing what's going on? Well, that's a philosophical argument more than a scientific one.

Bear in mind that even in Newtonian physics, people have no idea why two masses have an attractive force between them. These kinds of questions aren't answered by physics. Physics aims to describe the world by noticing regularities in nature; in fact, the same could be said of all science. You can keep pushing the questions back as far as you like:

What causes an apple to fall off a tree? Gravity.
What causes gravity? Mass.
What causes mass? The big bang.
What causes the big bang? ??????

some professors like explainin distortion of space time using the waterbed analogy..if a ball is placed on a waterbed then it gets depressed n say marble in the vicinity of the depression sorta rolls into the pit...similarly earth depresses space time..but in a higher dimension fashion...arnt i right?

Yes, but as with all analogies you should be careful of pushing this one too far. In fact, you've seen what the problem is:

but the ball distorts the bed because of the pressure applied on the bed which is in turn caused by its weight which is in turn the effect of a force field(gravitational field) and also if the ball were blaced on a wooden table there would be no distortion which means the fabric of the medium in which it is placed is important,which actually is the elasticity of the medium.

The analogy relies on a pre-existing force. But in the curved spacetime description of relativity, the curvature itself is the description of the apparent force. This is where the analogy fails. No "extra" force is needed to make an object follow local spacetime curvature, whereas an extra force seems to be needed for a ball to follow the curvature of a trampoline.

so for mass to distort space time ..there should be some background field...maybe force/energy/unknown factor...which sort of causes the 'pressure' of the mass on space time....and im also suggesting that space time has sum sort of 'elastic' factor....which may or may not be uniform..

The question is: what do you hope to gain in terms of explanatory power by introducing such a force? Will it give us a more useful description of gravity? Will it solve any problems which we can't solve without it?

hey ur sayin mass distorts space time because u need gravity to work tht way..
but i always thot gravity works tht way BECAUSE mass distorts space-time..
yeah n i guess these r fundamental laws,just like u said newtonian physics does not explain why 2 masses attract each other....its just that if we explore in detail we could understand better..which is one of the goals of science...
n yeah as i said the elastic idea could account for sum percentage of dark matter..its just an idea...basically i wanted to know whether there were any other proposed reasons as to why mass bends space time....apart from the fact that we want it that way so we can explain gravity..
n also do u think its the motion of masses which could be the reason it distorts space time? u know like a stone flung into water...throughout its journey it causes a sort of suction..n extend it to higher dimension...so that way we dont need the idea of a background field...just wondering again...i hope im not wastin ur time..

n yeah as i said the elastic idea could account for sum percentage of dark matter..

How, exactly?

basically i wanted to know whether there were any other proposed reasons as to why mass bends space time....apart from the fact that we want it that way so we can explain gravity.

Not that I'm aware of. Nobody knows why mass causes gravity. It just does.

n also do u think its the motion of masses which could be the reason it distorts space time?

No. Mass doesn't have to move to have gravity.

Not that I'm aware of. Nobody knows why mass causes gravity. It just does.



James R:

How can you make statements like that and yet at the same time back relativity, knowing that relativity cannot account for the cause of gravity?

Have you ever stopped to think that there might be an alternative and real physical reason for gravity ant it's effects?

Don't you think that making statements like "It just does" is a little shallow minded!

yeah...it just hit me as real strange that physicists so far never thought why mass bends space time thus causing gravity,i thot maybe i never came across it in the literature....since im just a 19 yr old graduate student...but i got a fair idea abt cosmology n relativity n such.
ok suppose the universe has a sort of elasticity...not the physical elasticity that we encouter everyday...but an analogical factor...maybe we can deduce it mathematically....n if this elasticity of the universe isnt uniform...that is there r regions some of which r less elastic than others...then at these regions..the same mass would cause more distortion(thus more gravitational effect) than what we expect....does that makes sense?
moreover,about motion.....everything in the universe IS moving...nobody knows wht wud happen at absolute rest...so maybe it is this motion which causes sort of like a thrust to space time....n that way we wont require a background field or even this elastic idea....like even in zero gravity space a ball could bend a water bed if it is FLUNG on to it...i hope i am right?temme if im wrong....
the change in momentum would have an impact on the fabric...distorting it...so the continuous motion of bodies through space time might be wht causes it to bend? n we all know velocity has an important role to play in relativity n the functioning of the universe etc.

dav57:

Don't you think that making statements like "It just does" is a little shallow minded!

No. All physics ultimately comes to that.

Why do three quarks combine to make a baryon? Nobody knows.
Why are there only three families of neutrinos, and not four or seventeen? Nobody knows.
Why are there only four fundamental forces, and not three or six? Nobody knows.
Why is there something rather than nothing? Nobody knows.
Why is the electron mass 9.1 × 10^-31 kg, and not some other number (perhaps 8.7 × 10^-31 kg, say)? Nobody knows.

There are lots of questions like this. Maybe one day we'll find the answers to some of them, but if so, it won't be by looking for them directly. Where would we start? Nobody knows. The best approach is to go ahead and describe what we see as accurately as we can. When we do that, inevitably we get unexpected insights into things we didn't initially think were connected.

yeah.agreed.was just wonderin if there were answers that i ws unaware of.thank u james

James R:

So you obviously agree that nobody knows or understands the cause of gravity but are implying that there could be a good reason for it, and that science could well uncover these reasons some time in the future.

may I ask you a question.....What do YOU think causes gravity? And please don't mention relativity because relativity only describes the observations in a mathematical sense. I'm trying to understand the REAL cause in physical terms.

We all know by now, James R, that relativity fits in perfectly with observations but fails to pin down the root causes.

dav57:

I have no idea what causes gravity. I know it is associated with mass and energy, but why they cause gravity I have no idea.

Do you think gravity needs a cause?

Maybe God causes gravity. Maybe you can't have a stable universe without gravity. Maybe gravity is a quantum field made of spin 2 gravitons which come into being via some mysterious fundamental interaction which incorporates all four forces we now call "fundamental".

The thing is, it is very easy to dream up possible causes. But science is about testing and observation and evidence. If you have no evidence, your dream is not much use. Well, actually, it's ok as long as there is, in principle, some way to test it. But untestable concepts are unscientific; they must be based on faith so they're more like a religion than a science.

is there any way of achieving absolute rest? like if sumbody manages to get out of a gravitational system like a galaxy or a galaxy cluster n is in free space,would they still move along with the expanding universe?
im askin abt absolute rest so my idea of motion causing gravity can be verified that way? or is there a simpler way of achieving absolute rest on earth(though i think thts impossible coz i mean our earth;s continuously moving)
im tryina think of more ways to verify my suggestions..i'll post em when im satisfied with them...

According to relativity, there is no absolute standard of rest.

gravity is supposed to be distortion of space time by mass right?
but can anybody tell me WHY does mass distort space time at all?
i would like to have the 'conventional' answers or whatever is mentioned in relativity...i would love to hear ur own ideas..but pls mentions if they r so so tht i wont be confused...
i am not a relativity expert or anything but i know some about it,but i never got to read or hear anything on why exactly mass distorts space time.
i really wanna know coz this really amazin idea fer an alternate hypothesis hit me but i wanna clear some of my concepts before trying to derive it mathematically.
thanks a lot.

You have asked for personal ideas that are not yet accepted or fully supported.

I am pleased to direct you to my own web site for some alternative thinking on the issue. Have fun.

http://www.paygency.com/

dav57:

I have no idea what causes gravity. I know it is associated with mass and energy, but why they cause gravity I have no idea.

Do you think gravity needs a cause?

Maybe God causes gravity. Maybe you can't have a stable universe without gravity. Maybe gravity is a quantum field made of spin 2 gravitons which come into being via some mysterious fundamental interaction which incorporates all four forces we now call "fundamental".

The thing is, it is very easy to dream up possible causes. But science is about testing and observation and evidence. If you have no evidence, your dream is not much use. Well, actually, it's ok as long as there is, in principle, some way to test it. But untestable concepts are unscientific; they must be based on faith so they're more like a religion than a science.

James R., after all this time and you have "NO" idea. Let me suggest once again that some people have offered ideas on this subject but your response has been, "I don't need to no." "I am not interested." "That is philosophy not science." :D

from my understanding; the gravity of all mass pulls on watever ius around it, if nothing is there it pull on nothing(space)

from my understanding; the gravity of all mass pulls on watever ius around it, if nothing is there it pull on nothing(space)

Gravity may not be a pull at all but a push from space.

hey u know MacM your universal kinetic field could be the background field tht i ws suggesting :-D u think so?
i dont wanna explain my idea in more detail because it would look too lame/pseudoscientific in this forum...but if u wanna i'd love u to tell u my idea..maybe u could incorporate it in ur theory or sumthing?

hey u know MacM your universal kinetic field could be the background field tht i ws suggesting :-D u think so?
i dont wanna explain my idea in more detail because it would look too lame/pseudoscientific in this forum...but if u wanna i'd love u to tell u my idea..maybe u could incorporate it in ur theory or sumthing?

:D Got my hands full with UniKEF as it is but you are welcome to join:

http://groups.msn.com/McCoinUniKEFTheory/home.htm

Throw your ideas around there and let the members kick them around.

okay then *kicks the idea out the window*

*catches it n throws it back*
:D

MacM:

Perhaps you should have actually read my post when you quoted it in your reply. I have plenty of ideas. But if I have no evidence which supports them, they're just pie in the sky.

MacM:

Perhaps you should have actually read my post when you quoted it in your reply. I have plenty of ideas. But if I have no evidence which supports them, they're just pie in the sky.

James R., don't get sensative on me. I merely quoted your post. In it "YOU" said "I have no idea what gravity is".

Am I correct that you have on numerous occasions also said "I don't need to know", "I don't want to know", etc?

If you are shifting your stance a bit I would see that as a positive and welcome move. But please don't accuse me of not reading your post or mis-quoting you.

MacM,


If you are shifting your stance a bit I would see that as a positive and welcome move. But please don't accuse me of not reading your post or mis-quoting you.

Let me remind you. You mis-interpreted my posts so...so many times. You also often mis-interpreted what written in the books. I would say that is one of your serious weakness. Even when someone suggested you to relook into your own post to correct your own mis-interpretation, you refused. That was another of your weakness, being sloopy and stubborn. Do you think to be a good scientist, someone need not quote from others or books accurately? Well, I know you are not a scientist and also you are not young anymore...so, you don't have to worry so much about those qualities.

Anyway, this is just a wake up call for you. You can carry on sleeping, nobody care. :D

MacM,

Let me remind you. You mis-interpreted my posts so...so many times.

Ditto to you.

You also often mis-interpreted what written in the books. I would say that is one of your serious weakness.

That is in fact rare and your opinion is worthless.

Even when someone suggested you to relook into your own post to correct your own mis-interpretation, you refused.

Bullshit.

That was another of your weakness, being sloopy and stubborn.

Sloppy? Only when it comes to those that want to knit pick posts rather than address the issues. I grant you that ome here are sticklers in that regard.

Do you think to be a good scientist, someone need not quote from others or books accurately? Well, I know you are not a scientist and also you are not young anymore...so, you don't have to worry so much about those qualities.

Funny. Ever hear the adage the knowledge and experience of the elderly? You might do well to come down of your self imposed mount and learn some also.

Anyway, this is just a wake up call for you. You can carry on sleeping, nobody care. :D

Better napping than brain dead. :D

MacM:

I have never changed my position on this. Perhaps my point of view is a bit subtle for you to understand.

My conception of "what gravity is" is based on science, not fantasy. While I might dream up all kinds of underlying "mechanisms" for gravity, to do so would be worthless, as such mechanisms are inaccessible to scientific investigation. I can imagine little green pixies pushing particles around in such a way that all the laws of gravity are reproduced, but do the pixies add anything useful to our pixture of gravity? Of course not.

MacM:

I have never changed my position on this. Perhaps my point of view is a bit subtle for you to understand.

Ditto


My conception of "what gravity is" is based on science, not fantasy. While I might dream up all kinds of underlying "mechanisms" for gravity, to do so would be worthless, as such mechanisms are inaccessible to scientific investigation. I can imagine little green pixies pushing particles around in such a way that all the laws of gravity are reproduced, but do the pixies add anything useful to our pixture of gravity? Of course not.

Unless of course the truth of it is that gravity is little green pixies pushing particles around. :D

Why would you assume that any underlying mechnisim is inaccessable to research? The only guarantee of that is if one does not attempt to look for the mechnisim.

You're still missing the point. Your 'underlying mechanism' is nothing more than a guess.

It would be one thing if you had some form of logic or proof to support it. You have neither.

You're still missing the point. Your 'underlying mechanism' is nothing more than a guess.

It would be one thing if you had some form of logic or proof to support it. You have neither.

I do not here intend to make more of it than it is but only point out that there is good logical reasons to believe the "guess".

Indeed I am looking forward to having the mathematical basis to adjust the time-space dimensions of the universe per UniKEF to fit Mercury's orbit and then use that scale of the universe to see if the UniKEF integration falls in line with observed rotational anomaly of stars around galaxies.

If those two points fit then I suggest you should take another look at the concept. If not then it will finally be over but not before.

but can anybody tell me WHY does mass distort space time at all?
i would like to have the 'conventional' answers or whatever is mentioned in relativity...i would love to hear ur own ideas..but pls mentions if they r so so tht i wont be confused...

I think relativity theory does not have a conventional answer.

My idea, an unsupported hunch at this point, is that gravity (the distortion of spacetime by mass) is Lorentz contraction (special relativistic length contraction). Distances are measurably reduced by Lorentz contraction, which in turn is caused by acceleration. Particles as tiny as electrons accelerate within all matter. Perhaps this acceleration contracts the spacetime around matter in a way that adheres to the inverse square law. This explanation doesn’t require gravitons, hypothesized particles that work between the earth, say, and every other object in the universe to enable the gravity. Lorentz contraction is effectively action at a distance.

I think relativity theory does not have a conventional answer.

My idea, an unsupported hunch at this point, is that gravity (the distortion of spacetime by mass)

We could agree to here.

is Lorentz contraction (special relativistic length contraction).

I don't make that connection.

Distances are measurably reduced by Lorentz contraction, which in turn is caused by acceleration. Particles as tiny as electrons accelerate within all matter. Perhaps this acceleration contracts the spacetime around matter in a way that adheres to the inverse square law.

Ufortunately the inverse square law is grossly invalid on cosmic scales.

This explanation doesn’t require gravitons, hypothesized particles that work between the earth, say, and every other object in the universe to enable the gravity. Lorentz contraction is effectively action at a distance.

I do agree only that gravity may be a quantum affect and "action at a distance".

Ufortunately the inverse square law is grossly invalid on cosmic scales.

How so?

How so?

Reference the following attachment (Link)

http://www.sciforums.com/attachment.php?attachmentid=2974&stc=1


The blue symbols are actual star motion observations. The MOND Curve stands for Modified Newtonian Dynamics, a new theory advanced, Ad Hoc, to change the mathematics of Newton's 1/r^2 to make it fit observation. Newtonian gravity is shown on the lower curve and is grossly in error except for a range limited to approximately 0.1 light years distance.

I will have to disagree with you here, Mac. I don't know where you got that diagram,
(MOND site, perhaps?) but it is not correct according to the actual latest observations
and data from WMAP and SDSS. MOND was considered, but failed to produce the
results that were consistant with the data. It has been rejected, as I have told you
before and gave you links to the WMAP data and results. Newtonian mechanics did not
give 'grossly inaccurate results', it indicated a presence of unseen mass, Dark Matter
of course. It has nothing to do with cosmic distances to the galaxies, but the mass
of the galaxies themselves and MOND could not explain the unusual rotations within
the galaxies and speed of the rotations either.

I will have to disagree with you here, Mac. I don't know where you got that diagram,
(MOND site, perhaps?) but it is not correct according to the actual latest observations
and data from WMAP and SDSS. MOND was considered, but failed to produce the
results that were consistant with the data. It has been rejected, as I have told you
before and gave you links to the WMAP data and results. Newtonian mechanics did not
give 'grossly inaccurate results', it indicated a presence of unseen mass, Dark Matter
of course. It has nothing to do with cosmic distances to the galaxies, but the mass
of the galaxies themselves and MOND could not explain the unusual rotations within
the galaxies and speed of the rotations either.

I am not a MOND supporter. I am showing the difference between Newtonian (inverse square) and actual star velocity. If one assumes the presence 4-5 times the observed mass, just located in the right locations, then yes things can be claimed differently. But Newtonian inverse square based on actual mass known to exist does not compute.

It would appear that tests that seem to indicate Dark Matter may very well also indicate a failure of the Newtonian concept and not presence of Dark Matter. Until it is somehow verified directly neither solutions has a claim to truth.

Since my own work favors the integration concept which appears to supply a means of changing gravity mathematics to coincide with observation, I take presence of Dark Matter with a grain of salt (as well as my own concept).

Either or Neither may be the truth.

And, of course, neither would UniKEF since it is only 'slightly' different than inverse square. And neither did MOND or any other alternative theory of
gravity.

And, of course, neither would UniKEF since it is only 'slightly' different than inverse square.

Oh dear.. you shouldn't have said that 'coz now all hell is gonna break loose again ;)

And, of course, neither would UniKEF since it is only 'slightly' different than inverse square. And neither did MOND or any other alternative theory of
gravity.

No. You clearly do not understand the concept and the subsequent mathematics that would support it.

The following is a crude graph in the difference of the functions.

http://www.sciforums.com/attachment.php?attachmentid=2975&stc=1

Rather than turning this into another UniKEF debate and getting off topic, the following link gives adequate explanation as to how such curve becomes generated.

http://www.paygency.com

Oh dear.. you shouldn't have said that 'coz now all hell is gonna break loose again ;)


:D Not really just a graph to correct a misunderstanding of principles.

:D Not really just a graph to correct a misunderstanding of principles.
It is not the first time that you show this graph. Please, could you explain it, and how this graph gives validity or invalidity of the 1/r^2?

1100f,

" Not really just a graph to correct a misunderstanding of principles. ”

It is not the first time that you show this graph. Please, could you explain it, and how this graph gives validity or invalidity of the 1/r^2?

I would love to but to keep within James R., intent of the thread he started and to not sidetrck this thread which I didn't start, I will do so over on the UniKEF thread.

See: http://www.sciforums.com/showthread.php?p=617811#post617811

I'll be posting info there for your consideration.

1100f,

You may have deleted this post since I don't see it here but it shows in my e-mail.

Why did I have this feeling that you won't give me the explanation?

But just in case this is to inform you that a detailed explanation is given in the UniKEF Analysis topic. Link provided above.

1100f,

You may have deleted this post since I don't see it here but it shows in my e-mail.



But just in case this is to inform you that a detailed explanation is given in the UniKEF Analysis topic. Link provided above.
After posting this, I have seen that you indeed replied to this post in another thread, so it was irrelevant, this is the reason that I deleted it.