# A Question for Curved Spacetime.

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The existence of matter tells space how to curve, and curved space tells matter how to move. This is layman's terms to basic principle Behind Einstein's Genius thinking and is the heart of Relativity. Einstein's successfully linked for the first time, the phenomenon of gravity with that of spacetime and relativity. If mass exist anywhere in the Universe ,spacetime around it will curve.  But depending on a few variables can affect how much. But if you take away the mass causing this Warped Spacetime, what causes the "Curved Fabric of Space"  return to its previous state,  into its unbent position?

Edited by J.Merrill
Missing question

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It's spacetime that's curved. Not fabric of space.

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31 minutes ago, J.Merrill said:

But if you take away the mass causing this Warped Spacetime, what causes the "Curved Fabric of Space"  return to its previous state,  into its unbent position?

The fact that the mass is gone that was warping spactime.

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3 hours ago, mistermack said:

It's spacetime that's curved. Not fabric of space.

The fabric of space is space time you didn't really argue anything here.

Its the fact that mass causes warped spacetime, and this in return causes gravity.

Edited by J.Merrill
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3 minutes ago, J.Merrill said:

Its the fact that mass causes warped spacetime, and this in return causes gravity.

Warped spacetime IS gravity.

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3 hours ago, Bufofrog said:

The fact that the mass is gone that was warping spacetime.

This does not explain anything, the question is why all of this happens in the first place. Why does Mass have an affect on Spacetime which causes Gravity.

Newton described Gravity as Action from a distance.

His Fg = m1 *m/rwas later proven to be flawed even though it worked on everything, except it contradicted its self when it came down to light.

This was later replaced by space time curvature by Einstein And that gravitation isn't determined by mass and position directly, but by the curvature of space, which itself is determined by the full suite of matter and energy throughout the Universe. If the Sun were to just immediately blink from existence, disappearing from the Universe, we wouldn't know for some time. Earth wouldn't Immediately fly off in a straight line; it would continue orbiting the Sun's previous location for another 8 minutes and 20 seconds. In this we can conclude its not mass that determines gravitation, but rather the curvature of space.  And that is determined by the sum of all matter and energy in it.

So taking away the sun, this would cause space to go from being curved to being flat, but that transformation isn't an instantaneous. Because spacetime is a fabric, that kind of instant transition would have to occur in a form of snapping motion, which would send very large ripple/ gravitation waves through out the universe propagating outward like ripples in a pond. Because this transition is slow . This mean there is another force or phenomenon at work here.

3 hours ago, Bufofrog said:

Warped spacetime IS gravity.

Yes I agree with this it is not my intentions here to disregard and discredit this.

Edited by J.Merrill
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19 minutes ago, J.Merrill said:

Why does Mass have an affect on Spacetime which causes Gravity.

The answer is, that is not a physics question, that is a philosophy question.  Just like the question, "why does a positive charge attract a negative charge" is a philosophy question.

Edited by Bufofrog
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3 hours ago, Bufofrog said:

The answer is, that is not a physics question, that is a philosophy question.  Just like the question, "why does a positive charge attract a negative charge" is a philosophy question.

I disagree, physics derived from questioning things just like this, and to just shove aside questions like these in the physics community only shows the lack of answers.

If questions to unanswered problems is philosophy then what do we really understand, if every thing just creates another problem that cant be answered.

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8 minutes ago, J.Merrill said:

I disagree

That's fine, but most physicist agree with me.

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3 hours ago, Bufofrog said:

That's fine, but most physicist agree with me.

Physics a branch of science related to the study of basic or complex laws of nature and their manifestations , related to different natural occurring phenomena.

For Physics to even be what it is you must question explanations in their own right of answers, until you have a definitive proof and no questions are left.

Philosophy is simply the Science of Science.  It can also be considered the "fundamental  science"  It is the question WHY? That we have arrived at any conclusion we can't just not include philosophy from science.

Edited by J.Merrill
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1 hour ago, J.Merrill said:

For Physics to even be what it is you must question explanations in their own right of answers, until you have a definitive proof and no questions are left.

Proof is not really the realm of science.  Theories are never proven, they are only supported by the evidence

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2 hours ago, J.Merrill said:

The fabric of space is space time you didn't really argue anything here.

No, you're not getting it. Spacetime is the shape of space, over time.

In other words, space does not curve, as you state in the OP. If you are picturing curved space, and asking why it returns to it's "unbent" condition, then you are talking about something that doesn't exist. Spactime is a model combining three spatial dimensions with the time dimension. You combine uncurved space with time, in a gravitational field, and you get a curved four dimensional model.

Picture a brick, in space, rotating round a fixed point on a tether. Forgetting losses, it will rotate forever. You can model it as spactime having a constant curve, making a circular path. As soon as you release the tether, the brick will instantly travel in a straight line. Space was never curved, it was the tether that made the brick rotate.

A satellite oribiting the Earth would do exactly the same thing, if the Earth suddenly lost it's gravity, for the same reason. It's lost its "tether".  It's not space "springing back straight", it was never curved. You are just confusing curved spacetime, with curved space.

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3 hours ago, mistermack said:

No, you're not getting it. Spacetime is the shape of space, over time.

I'm not sure you understand what I stated, did you even read all of it or simply take things out of context and claim I don't understand?

Gravity is the curvature of the universe, caused by massive bodies, which determines the path that an Object Travels. That curvature is dynamic, it is moving as Celestial bodies move through Space and Time Spacetime. It was Einstein's view of the world , that changed the view of gravity to the understanding that is the direct result of Curved spacetime caused by Mass.

To argue this as you have quoted me, is to argue Einstein.

Edited by J.Merrill
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John Wheeler came up with this wonderful phrase to summarise what GR is about. But buzzwords can only get you so far. If you have a situation in which a small object moves in the vicinity of a stellar object that heavily distorts space-time around it, then it's fair to say that the star tells space-time around how to bend, while the relatively small stuff moving close is told how to move. However, consider the collision of two black holes. In that case, both the motion of the objects and the warping of space-time are very difficult to tell apart. For those cases, the only alternative is to appeal to the equations and have a computer solve them for you. The equations are highly non-linear, which means that ultimately it's impossible to express the warping as the sum of contributions of this and that piece of matter. Gravity itself gravitates. See my point?

Another aspect I would like to point out is that mass is not the source of the gravitational field. It's energy-momentum that plays that role.

The "mental operation" that you're proposing here, if I've understood you correctly, is to remove the sources and be left with an empty space-time, and then you ask yourself what shape does that space-time have. Well, think about this: Einstein's field equations have many solutions corresponding to an empty space-time. Gravitational waves are a particular example of solutions to the Einstein vacuum equations.

So I guess my answer is: No, you can't figure out what space-time is like with nothing in it. Not a priori. You have to make a guess.

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3 hours ago, mistermack said:

A satellite orbiting the Earth would do exactly the same thing, if the Earth suddenly lost it's gravity, for the same reason. It's lost its "tether".  It's not space "springing back straight", it was never curved. You are just confusing curved spacetime, with curved space.

To explain gravity like this is to try and explain gravity with gravity that does not work.

Your tether is gravity and to lose the tether is to lose gravity and that makes not sense at all.

If you jump into the air, your head is moving through time slightly faster than your feet. This time gradient results in motion, not towards the source of gravity but along the curvature of space time.

Time causes gravity. Gravity is not a force, it is an effect of spacetime curvature.

The effect is know as "Gravitational Time Dilation" It is predicted by Einstein's theory of General Reactivity and has been verified with Multiple experiments.

3 hours ago, joigus said:

John Wheeler came up with this wonderful phrase to summarise what GR is about. But buzzwords can only get you so far. If you have a situation in which a small object moves in the vicinity of a stellar object that heavily distorts space-time around it, then it's fair to say that the star tells space-time around how to bend, while the relatively small stuff moving close is told how to move. However, consider the collision of two black holes. In that case, both the motion of the objects and the warping of space-time are very difficult to tell apart. For those cases, the only alternative is to appeal to the equations and have a computer solve them for you. The equations are highly non-linear, which means that ultimately it's impossible to express the warping as the sum of contributions of this and that piece of matter. Gravity itself gravitates. See my point?

Another aspect I would like to point out is that mass is not the source of the gravitational field. It's energy-momentum that plays that role.

The "mental operation" that you're proposing here, if I've understood you correctly, is to remove the sources and be left with an empty space-time, and then you ask yourself what shape does that space-time have. Well, think about this: Einstein's field equations have many solutions corresponding to an empty space-time. Gravitational waves are a particular example of solutions to the Einstein vacuum equations.

So I guess my answer is: No, you can't figure out what space-time is like with nothing in it. Not a priori. You have to make a guess.

Yes and thank you!

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5 hours ago, J.Merrill said:

But if you take away the mass causing this Warped Spacetime, what causes the "Curved Fabric of Space"  return to its previous state,  into its unbent position?

How do you “take away” the mass? It’s the energy it represents that matters, so it can’t just disappear.

If you try and analyze a situation that violates physical law, you can’t get a valid answer.

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2 hours ago, swansont said:

How do you “take away” the mass? It’s the energy it represents that matters, so it can’t just disappear.

I'm not entirely sure how people take things so literal, the question I am proposing still stands and is still unanswered.

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5 hours ago, J.Merrill said:

The existence of matter tells space how to curve, and curved space tells matter how to move. This is layman's terms to basic principle Behind Einstein's Genius thinking and is the heart of Relativity. Einstein's successfully linked for the first time, the phenomenon of gravity with that of spacetime and relativity. If mass exist anywhere in the Universe ,spacetime around it will curve.  But depending on a few variables can affect how much. But if you take away the mass causing this Warped Spacetime, what causes the "Curved fabric of space"  return to its previous state,  into its unbent position?

matter = mass x Length dimension

1 hour ago, mistermack said:

You combine uncurved space with time, in a gravitational field, and you get a curved four dimensional model.

You can use a spherical, elliptical, or hyperbolic curvature for G.R., no?

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Just now, J.Merrill said:

I'm not entirely sure how people take things so literal, the question I am proposing still stands and is still unanswered.

You are asking what physics says about a situation that is unphysical. Physics has nothing to say about it.

Just now, NTuft said:

matter = mass x Length dimension

No.

Please don’t make stuff up and post it. Matter is a description; it has no units.

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2 hours ago, NTuft said:

matter = mass x Length dimension
You can use a spherical, elliptical, or hyperbolic curvature for G.R., no?

Matter is the presence of  energy, called "rest energy" What distinguishes the matter - energy from other forms of energy is that all "Matter" Has inertia and is subject to the force of gravity, when at rest and as well as when in motion.

About a 4D model.... hmm no, you can't make a 4D model but only a 3D representation of 4D space and it's still not as it would be in a real 4Dimensional world.

There are many forms like Tetrahedron or a 24 cell. A Hyper Sphere or maybe a tesseract.  All of these we can only under stand 3 Dimensionally.

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12 minutes ago, swansont said:

No.

Please don’t make stuff up and post it. Matter is a description; it has no units.

I need a more concrete description, so I tried to define it.

How would you describe or define matter? I do think this is at issue from the premise, "The existence of matter tells space how to curve...".

5 minutes ago, J.Merrill said:

Matter is the presence of  energy, called "rest energy" What distinguishes the matter - energy from other forms of energy is that all "Matter" Has inertia and is subject to the force of gravity, when at rest and as well as when in motion.

About a 4D model.... hmm no, you can't make a 4D model but only a 3D representation of 4D space and it's still not as it would be in a real 4Dimensional world.

There are many forms like Tetrahedron or a 24 cell. A Hyper Sphere or maybe a tesseract.  All of these we can only under stand 3 Dimensionally.

Thank you. Technically, I was not asking you the second part, but thanks anyway.

Edited by NTuft
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3 hours ago, swansont said:

How do you “take away” the mass? It’s the energy it represents that matters, so it can’t just disappear.

If you try and analyze a situation that violates physical law, you can’t get a valid answer.

Every theory violates physical laws, and they are only laws because we say they are. The big bang is full of things that point in the right direction but creditably fall apart at the source.

It's like asking to describe the universe before the big bang.  You can't represent physically what it is, a singularity is infinitely small, it has no Dimension so describing it as a simple dot does not do anything. Because a dot has a physical length and width.

The only reason we say energy can only be transformed and transferred , never destroyed is because we say so.

1.) Law of Thermodynamics, Energy can be changed from one form to another, but cannot be created or destroyed, the total amount of energy and matter in the universe remains constant, merely changing from one from to another. Why? Because we said so, and built a foundation around this.

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18 minutes ago, NTuft said:

I need a more concrete description, so I tried to define it.

The classical view is matter has mass and takes up space. A deeper dive shows that it’s anything comprised of fundamental fermions.

9 minutes ago, J.Merrill said:

Every theory violates physical laws

Bullshit. Back this up.

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14 minutes ago, swansont said:

The classical view is matter has mass and takes up space. A deeper dive shows that it’s anything comprised of fundamental fermions.

Bullshit. Back this up.

Composite fermion, proton: " Because protons are not fundamental particles, they possess a measurable size; the root mean square charge radius of a proton is about 0.84–0.87 fm (or 0.84×10−15 to 0.87×10−15 m)"

Unclear distinction between fermions and baryons, from a short wikipedia expedition.

Edited by NTuft
--sorry, I clearly missed, "fundamental" as your qualifier.
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3 hours ago, swansont said:

Bullshit. Back this up.

Theories are theories because they can be verified and falsified. And we don't just verify and falsify based on being skeptic alone.

We back these verifications or falsifications with Math that is either directly inline  with laws of physics we set in place.

As my suggestion of removing matter like the sun in my explanation.

The Big Bang is one of many theories with many obvious violations and unverified answers to problems.

The Big Bang

It violates the first law of thermodynamics, which says you can't create or destroy matter or energy.

The first long-lived matter particles of any kind were protons and you guessed it neutrons. And together they make up the atomic nucleus. These came into existence around of 0.0001 a second after the Big Bang, Before that there was really no material in any familiar sense.

Why do you think people purpose alternative explanations to the origins of the universe? Because they can for one and for two they have reason to believe based on knowledge that it was flawed in some way. And these flaws derived from questioning things.

How do you think relativity was born.

I'm not listing all theories and the flaws but they all have them and the flaws either mean 2+2 =5 or in other words violates things we presume are not true or have evidence of.

Edited by J.Merrill

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