[Anilkumar]

dimreepr, on 2 December 2011 - 05:01 PM, said:

Hi anilkumar I see you've posted on my thread that "theory" explains it. As for the maths I'd need alot of help 2 express.

I feel 'Theory' gives a feel of whats happening.

And Mathematics gives a proof of it.

[guenter]

Anilkumar, on 1 December 2011 - 04:38 AM, said:

If there was a Rocket, shuttling between those two points at a fixed uniform velocity, prior to our bringing Earth near them;

will now take less time or may be more time, to reach between the points, after we place Earth near them?

for the person observing from far away.

Replacing the rocket by radar signals, we talk about the Shapiro Delay. Those signals reflected by mars take more time to return to earth in case they pass near by the sun than compared to an analogous measurement without the sun. The effect is tiny but measurable and demonstrates the spacetime curvature due to the sun.

[IM Egdall]

Anilkumar, on 2 December 2011 - 04:49 PM, said:

Is this similar to Space warp due to Gravity. The difference being that, the Magnet deflects the Magnetic-needle, whereas Gravity deflects everything with mass & even Time.

Like saying;

if there is a Ball on top of a Table. Instead of saying 'The Ball is on the Table' we say 'The Table is under the Ball'.

Instead of saying 'Gravity influences Motion' we say 'Gravity warps Space'.

With all this writing as above;

Am I anywhere near interpreting the phenomenon of Space-Time warp?

You are close. However, it is not quite correct to say "gravity warps space." It is better to say the presence of mass/energy warps space (and time). LIke the presence of the Sun warps space and time in its vicinity.

And this warping or curvature of space and time (spacetime curvature) is what causes planets to orbit the Sun and holds us down to the Earth. We call this effect gravity. So spacetime warp or curvature IS gravity.

Physicist John Archibald Wheeler said something like "mass/energy grips spacetime and tells it how to curve -- and curved spacetime (gravity) grips mass/energy and tells it how to move."

This post has been edited by IM Egdall: 4 December 2011 - 03:27 PM

[Anilkumar]

IM Egdall, on 4 December 2011 - 03:24 PM, said:

You are close. However, it is not quite correct to say "gravity warps space." It is better to say the presence of mass/energy warps space (and time). LIke the presence of the Sun warps space and time in its vicinity.

And this warping or curvature of space and time (spacetime curvature) is what causes planets to orbit the Sun and holds us down to the Earth. We call this effect gravity. So spacetime warp or curvature IS gravity.

Physicist John Archibald Wheeler said something like "mass/energy grips spacetime and tells it how to curve -- and curved spacetime (gravity) grips mass/energy and tells it how to move."

If it is right to say that;

"Gravity influences Motion & Time"

Why are we creating unnecessary misunderstanding by saying, the other way round, that;

"Presence of mass/energy warps space &Time. And this warped space affects motion. This effect is called gravity".

While we very well know that;

• Space is a structureless entity. And so altering the structure of that entity which does not have any structure does not arise.
• We do not know how it can be done.

IM Egdall, on 2 December 2011 - 03:36 PM, said:

As to why mass/energy causes the warping of spacetime -- I think we need new physics to answer that. Maybe the combining of general relativity and quantum mechanics in a new theory of so-called "quantum gravity" will someday tell us why.

guenter, on 3 December 2011 - 04:14 PM, said:

Replacing the rocket by radar signals, we talk about the Shapiro Delay. Those signals reflected by mars take more time to return to earth in case they pass near by the sun than compared to an analogous measurement without the sun. The effect is tiny but measurable and demonstrates the spacetime curvature due to the sun.

I have no objection in the fact that the path & duration of the signals are altered.

But I have objection in how we say that.

We say that;

"mass/energy warps Space & Time and so, the Signals take the altered path".

I object this method of its interpretation, because, Space is a structureless entity. And there is no way, the structure of a structureless entity can be altered.

So instead I want us to say that;

"Mass has Gravity. And this Gravity alters the Direction and Duration of anything that is moving, in its vicinity"

This post has been edited by Anilkumar: 5 December 2011 - 06:23 AM

[guenter]

Anilkumar, on 5 December 2011 - 06:45 AM, said:

"mass/energy warps Space & Time and so, the Signals take the altered path".

I object this method of its interpretation, because, Space is a structureless entity. And there is no way, the structure of a structureless entity can be altered.

There is a way, Anilkumar. The Friedmann-Robertson-Walker cosmological model is derived from the einsteinian equations. Here the mass density is thought homogeneous like sugar in the tea. Being perfectly structureless, the curvature as expressed by the sum of the angles in a triangle can be hyperbolic, euclidian or spherical. Depending on the mass density.


@IM Egdall: "As to why mass/energy causes the warping of spacetime -- I think we need new physics to answer that."

Why? There is no need, as long as the predictions of the theory are in excellent agreement with the observation. The problem of General Relativity is the singularity.

[Anilkumar]

Thanks Quenter,

for your concern.

guenter, on 5 December 2011 - 10:01 PM, said:

There is a way, Anilkumar. The Friedmann-Robertson-Walker cosmological model is derived from the einsteinian equations. Here the mass density is thought homogeneous like sugar in the tea. Being perfectly structureless, the curvature as expressed by the sum of the angles in a triangle can be hyperbolic, euclidian or spherical. Depending on the mass density.

@IM Egdall: "As to why mass/energy causes the warping of spacetime -- I think we need new physics to answer that."

Why? There is no need, as long as the predictions of the theory are in excellent agreement with the observation. The problem of General Relativity is the singularity.

To act, one needs 'SOMETHING' to act on;

one cannot act on 'NOTHING' ;

SPACE is 'NOTHING' ;

it is 'EMPTINESS'.

Mass or mass density, denotes EXISTANCE of physical material, and Empty-Space denotes NON-EXISTANCE of anything.

Then,

how can something that 'exists' act on something that 'does not exist'.

The very proposition that Space i.e. 'INFINITE - EMPTINESS' has a geometrical shape of its own, is incomprehensible.

How can empty space, have a geometrical shape? It is like saying 'The Non-existent', 'THE-ABSENT', or 'THAT WHICH IS MISSING' has a shape of its own.

This post has been edited by Anilkumar: 6 December 2011 - 10:18 AM

[StringJunky]

Anilkumar, on 6 December 2011 - 10:17 AM, said:

How can empty space, have a geometrical shape? It is like saying 'The Non-existent', 'THE-ABSENT', or 'THAT WHICH IS MISSING' has a shape of its own.

The geometry of space is inferred or extrapolated from the observed behaviour of bodies within it.

[IamJoseph]

Anilkumar, on 6 December 2011 - 10:17 AM, said:

Mass or mass density, denotes EXISTANCE of physical material, and Empty-Space denotes NON-EXISTANCE of anything.

Magestic engineering is seen throughout the universe, as with the human body. However, unlike our engineering values, the starting point [origins] is an enigma.

Space is exactly the same matter as all other physical matter. This is the bottom line effect of Einstein's space bending premise. If space was 'nothingness' it could not bend! Space is a rarer form of matter, rarer than atmospheric matter, as in: solids; liquids; atmospheric matter [less rare; air]; non-atmospheric matter [still rarer - but never 'nothing']. Everything contained in the universe is basically the same matter - only their densities vary.

The real beguiling question is: where does it end? I don't refer to the horizonal or vertical mediums of space, but what does this bendable space rest upon? Remember that once there was no space - because once there was no universe. The expanding universe says that the space is expanding; the question thus remains, where is the space expanding to - and upon what foundation? The finite factor negates the existence of anything contained in the universe - to exist outside or not within the universe.



My answer: we cannot know the true 'origins' of anything. We do not know the origins of stars, life or pineapples.We get away from this enigma by wrongly accounting the universe as infinite [MV; Parallel Uni's]. But the expanding universe says it was not infinite 10 seconds ago.

guenter, on 5 December 2011 - 10:01 PM, said:

There is a way, Anilkumar. The Friedmann-Robertson-Walker cosmological model is derived from the einsteinian equations. Here the mass density is There is no need, as long as the predictions of the theory are in excellent agreement with the observation. The problem of General Relativity is the singularity.

There is no singularity in the universe, nor can there ever be according to scientific understandings. Basically, aside from the mathematical and theoretical perspective, a singularity aligns with the premise of one indivisible and irreducible entity, namely a pristine 'one'. A pure, pristine 'one' cannot exist in the universe: if it did it could not produce an action, which requires a minimum of two interactives. A sole and lone pristine one would remain the same at all times, namely it can be seen as an infinite entity, one which requires no other counterpart to exist or cause an action. We know also, that if the universe is finite - it cannot contain an infinite.It takes two to tango applies.

[Anilkumar]

StringJunky, on 6 December 2011 - 12:56 PM, said:

The geometry of space is inferred or extrapolated from the observed behaviour of bodies within it.

Why don't we accredit, the observed behavior of bodies, to their 'INHERENT PROPERTIES' ?

Why ascribe it to 'NOTHING'?


-------------------------**********************-----------------------------------

IamJoseph, on 6 December 2011 - 01:34 PM, said:

. . . Space is a rarer form of matter, rarer than atmospheric matter, as in: solids; liquids; atmospheric matter [less rare; air]; non-atmospheric matter [still rarer - but never 'nothing'] . . .

This does not accord with the definition of Space.

This post has been edited by Anilkumar: 6 December 2011 - 04:17 PM

[swansont]

Anilkumar, on 6 December 2011 - 04:15 PM, said:

Why don't we accredit, the observed behavior of bodies, to their 'INHERENT PROPERTIES' ?

Because a mass will not move or accelerate on its own. There is an external influence, and in GR, this is geometric in origin.

[IamJoseph]

Anilkumar, on 6 December 2011 - 04:15 PM, said:

Why don't we accredit, the observed behavior of bodies, to their 'INHERENT PROPERTIES' ?

Why ascribe it to 'NOTHING'?


-------------------------**********************-----------------------------------



This does not accord with the definition of Space.

But it does. Space is a less rare density of matter. The difference is in degree not in kind:

Quote

Vacuum
From Wikipedia, the free encyclopediaJump to: navigation, search This article is about empty physical space or the absence of matter. For other uses, see Vacuum (disambiguation). Pump to demonstrate vacuumIn everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure.^[1] The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in practice. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they simply call "vacuum" or "free space", and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. The Latin term in vacuo is also used to describe an object as being in what would otherwise be a vacuum.

The quality of a vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%.^[2] Much higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10⁻¹²) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm³.^[3] Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average.^[4] However, even if every single atom and particle could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, and other phenomena in quantum physics. In modern Particle Physics, the vacuum is considered as the ground state of matter.

[Anilkumar]

swansont, on 6 December 2011 - 04:46 PM, said:

Because a mass will not move or accelerate on its own. There is an external influence, and in GR, this is geometric in origin.

Seems appealing,

But where does the Geometry originate from?

Certainly,

the Space is incapable of providing it.




---------------------------------***********




IamJoseph,

Space & Vacuum are two different things.

IamJoseph, on 7 December 2011 - 12:48 AM, said:

But it does. Space is a less rare density of matter. The difference is in degree not in kind:

Does Physics say this?

This post has been edited by Anilkumar: 7 December 2011 - 06:09 AM

[swansont]

Anilkumar, on 7 December 2011 - 06:06 AM, said:

Seems appealing,

But where does the Geometry originate from?

Not really a question of physics.

Anilkumar, on 7 December 2011 - 06:06 AM, said:

Certainly,

the Space is incapable of providing it.

That would be a preconceived notion applied to the situation. Experimentally we see that it is indeed true.

[Anilkumar]

swansont, on 7 December 2011 - 10:59 AM, said:

Not really a question of physics.

That would be a preconceived notion applied to the situation. Experimentally we see that it is indeed true.

Well fine then,

what is the role of Differential Geometry, here?

ajb, on 4 June 2011 - 01:50 PM, said:

You will need to "pull apart" the Einstein field equations to understand this in proper detail . . .

DrRocket, on 25 November 2011 - 07:12 AM, said:

Differential geometry . . .

But:

• Experimentally we see that mass bends space.
• Physics is not interested in knowing about the origin [= why/how Mass bends EMPTY Space'.] of 'Geometry of Space or the origin of the 'Influence', for Motion', which also CLEARLY means, that: - 'Differential Geometry has no role in 'telling us' why/how Mass bends EMPTY Space'.
  
  Then what role does 'Differential Geometry' play, here?

This post has been edited by Anilkumar: 7 December 2011 - 03:26 PM

[swansont]

GR tells us how mass curves space, i.e. it gives us the details of the curvature. That's why differential geometry is involved. It does not tell us why this curvature happens.

[Anilkumar]

Great,

you have put this in right words,

"It does not tell us why this curvature happens".

swansont, on 7 December 2011 - 09:18 PM, said:

GR tells us how mass curves space, i.e. it gives us the details of the curvature. That's why differential geometry is involved. It does not tell us why this curvature happens.

Could you please elaborate on;

'What type of details are these?'

'Where, i.e., at what juncture, the services of Differential geometry is brought in & for what purpose?'

[swansont]

Anilkumar, on 8 December 2011 - 04:11 AM, said:

Great,

you have put this in right words,

"It does not tell us why this curvature happens".



Could you please elaborate on;

'What type of details are these?'

'Where, i.e., at what juncture, the services of Differential geometry is brought in & for what purpose?'

It gives you the equations.

[Anilkumar]

swansont, on 8 December 2011 - 10:43 AM, said:

It gives you the equations.

The Einstein's field equations?

[swansont]

Anilkumar, on 8 December 2011 - 01:38 PM, said:

The Einstein's field equations?

I was thinking of the solutions to them. But at this point you should be talking to someone who is better versed in GR than I.

[IM Egdall]

Anilkumar - May I suggest the following website as an intro to the use of differential geometry in general relativity. Check it out:

http://math.ucr.edu/home/baez/gr/