Thread: curvature of spacetime...

This was what einstein defined gravity, my point is that i could not figure out in what sense did he think the curvature and why would the mass curve the space time.
Is it because of the mass of an object and if it was so ,if space wasn't there then an object would continuously falling, is that what happens.

no.

Easy way to visualise it, try this at home. You need 2 chairs, 1 sheet, 2 balls of different sizes. Spread the chairs out as far apart as your sheet is long. Stretch the sheet so one end is on one chair and the other is on the other chair. The sheet is your space-time Now place the big ball on the sheet, it will be the sun. The ball will curve the sheet, that is gravity. Now place the smaller ball on the sheet, it will roll towards the bigger ball following the curve.

"If space wasn't there" If space wasn't there, what would be causing an object to fall? Gravity? No, gravity is the curvature of space. So why would an object fall if there is no space which also means there is no gravity. Hope this helps.

What do you mean by "fall"? Normally, this means the object would be attracted to another object due to gravity, and they would "fall" towards each other. However, if there is no gravitational attraction, what is this object going to fall to?

Originally Posted by shawngoldw

Easy way to visualise it, try this at home. You need 2 chairs, 1 sheet, 2 balls of different sizes. Spread the chairs out as far apart as your sheet is long. Stretch the sheet so one end is on one chair and the other is on the other chair. The sheet is your space-time Now place the big ball on the sheet, it will be the sun. The ball will curve the sheet, that is gravity. Now place the smaller ball on the sheet, it will roll towards the bigger ball following the curve.

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If i try doing this at home it is the same thing you are defining the gravity as the force, since chairs,ball,and the sheets are all under the influences of gravity , isn't it .

OK!! suppose if i do this experiments in the space, i should be consider the spacetime as the sheet as u have written and the earth as the small metal ball , then as the metal ball why doesn't the earth fall towards the sun and one more thing ,mercury, which is the nearest planet, had to be already falling. isn't it, why does this not happen?

AND if space wasn't there, its mass would have made an object to fall continuously. SInce spacetime act as the resisting force for the fall of an objects which you have considered the spacetime as an objects(sheet)

you took the experiment to litterally. You are right, it is all under the force of gravity that is why the experiment works. But that is why I said it is a good way to visualize it, not explain it.

OK!! suppose if i do this experiments in the space, i should be consider the spacetime as the sheet as u have written and the earth as the small metal ball , then as the metal ball why doesn't the earth fall towards the sun and one more thing ,mercury, which is the nearest planet, had to be already falling. isn't it, why does this not happen?

I'm not 100% sure I know what your asking here. I'll give you an answer based on what I thought you were saying but clarify your question if I'm wrong.

Your asking why doesn't the earth fall towards the sun, when in your experiment it does. In your experiment, instead of just placing earth, roll it at a 45 degree angle from the sun. It starts to orbit around the sun, but not for long. That is because of the gravity we experience, which isn't part of the experiment, and you haven't rolled it with the right force at the right angle.

The earth doesn't fall to the sun because it's orbit balances out the gravity. Well actually it is falling towards the sun a little bit every year, someone correct me if I'm wrong. But it is negligible for the short time we are alive. Mercury experiences the same effect.

AND if space wasn't there, its mass would have made an object to fall continuously. SInce spacetime act as the resisting force for the fall of an objects which you have considered the spacetime as an objects(sheet)

No, space-time does not act as a resisting force. It is not a force. It doesn't resist motion. An object moves through space-time only when force is applied to that object. Gravity is a force which causes things to "fall" as we have been wording it this whole time.

Without space-time, there would be no gravity because GRAVITY CURVES SPACE-TIME. Falling is the wrong term to use for this because falling is due to gravity, but lets stick with it anyways. As I said before, an object only moves when force is applied, if your standing around without space-time what is going to make you fall? Remembering that space-time does not resist motion and also, which way is down? Even if your thought was correct, the force pulling you down would be countered by the force pulling you up. Left would be countered by right. You would not move.

Of course, we've never had a way of testing gravity in a motionless system. The Earth itself spins, and revolves around the Sun.

For all we know, motion might actually be a component of what drives the force.

Motionless? What exactly is a motionless system?

Originally Posted by shawngoldw

you took the experiment to litterally. You are right, it is all under the force of gravity that is why the experiment works. But that is why I said it is a good way to visualize it, not explain it.

Ok then what can visualise mean, we can only visualise if we are convinced. like a steel ball needs a sheet to make a curve to the sheet which is both a matter , i think you know that a matter interact with matter,It's the interaction of the matter that the curve is created,i.e do you mean that spacetime is also a kind of matter or any kind of energy,i bet yes because how can matter act with nothing(spacetime).

Originally Posted by shawngoldw

Your asking why doesn't the earth fall towards the sun, when in your experiment it does. In your experiment, instead of just placing earth, roll it at a 45 degree angle from the sun. It starts to orbit around the sun, but not for long. That is because of the gravity we experience, which isn't part of the experiment, and you haven't rolled it with the right force at the right angle.

I did't really get what was your explanation.

Originally Posted by shawngoldw

No, space-time does not act as a resisting force. It is not a force. It doesn't resist motion. An object moves through space-time only when force is applied to that object. Gravity is a force which causes things to "fall" as we have been wording it this whole time.

If spacetime wasn't like a kind of resisting force then why is the sun is at it's fixed position rotating at very slow pace.I mean what is making that sun stay at a same position.

hey sorry for taking a while to make this reply I've been really busy. Visualizing this curve helps you understand because it is hard for people to believe or understand something if they can't see it. When we try to visualize it, we have to use matter for everything because that is what people can understand the easiest. Space-time is not matter. It's described as a fabric, which is a personification that we people give to it so we can understand it.

As for how can matter interact with nothing, although space-time is not matter, gravity is a force. Just like electromagnetism and the strong and weak nuclear forces. They all interact, if space-time was nothing then matter would not be able to interact with it because "nothing" can't be interacted with. But space-time is not nothing or matter.

I did't really get what was your explanation.

All I am trying to say is that the direction the earth and other planets move around the sun balance out the force of gravity to create a pretty much stable orbit.

If spacetime wasn't like a kind of resisting force then why is the sun is at it's fixed position rotating at very slow pace.I mean what is making that sun stay at a same position.

First of all, if space-time was a resisting force, why would that stop the sun from moving? Second of all, the sun may seem like it is not moving because it is at the center of our solar system. It is the densest and largest object in our solar system, that causes it to create the most gravitational pull and everything to orbit around it. Third, the sun IS moving. It is orbiting the center of the galaxy which is accelerating outwards from the center of the universe. I'm not sure about the speeds, but that is all happening VERY fast.

Originally Posted by newspaper

This was what einstein defined gravity, my point is that i could not figure out in what sense did he think the curvature and why would the mass curve the space time.
Is it because of the mass of an object and if it was so ,if space wasn't there then an object would continuously falling, is that what happens.

I do understand Einstein defined space-time as to be responsible for gravity. He assumed the objects like
planets, comets etc. twisting space-time. The closest I could get is he assumed space itself as to be
space-time resp. had mistaken space and space - time or was about to give space itself a new name. He
has seen time as being something in fact existent. I have no other clue.

In times of Einstein space missions, space travel, entering space in some way and receiving information
about weightlessness in particular was unknown. This also was a major fact which was not to
underestimate.

When you would do some research on the issue you will find no one, who was predicting some state of
weightlessness, anti gravity, microgravity as we are used to today. No one had an even theoretical idea
about that fact. First, known since space was entered. This was my outcome on the issue at least. That's
an very interesting phenomena btw., one's own kind. All the associated information, think about the
soaring water for example, were unknown to Einstein as well as to colleagues, previously. I will say he
built up his work with the help of information all missing information out of spaces characteristics. One
good sample I think is a boat going uphill on a river. As you are aftern on the boat throwing a plastic bottle
behind the ship the bottle will follow the ship, even uphill, for a while.

I think he imagined earth for example exposing this behavior to space as the planet moved trough the
universe. He also could have some tornado like invisible vortexes resulting from earths motion named as
to be his space-time.

I don't think objects in space would fall as space wasn't there. First, if spaces wasn't there, no other object
was there. All the objects which are in space need to get the materials they are made of from space in
some way and to the full extend of their volumes. Related to weightlessness, I would say gravity was the
own result of earth circling in space around the sun. As objects on earth have hit the ground, it becomes
clear the objects have even here on earth not have weight, actually, or were exposed to some forces
smashing them on the ground but they simply couldn't sidestep the approaching earth. That's all. Gravity
to me was an illusion due to unawareness of experiences.

As an interesting aside, there was like a legality in space as well. Similar to any object on earth will fall
to the ground. Objects won't fall some ever same direction but do move some way as well.

I mean earth circling the sun as well as other celestial bodies. Space was not a static environment
though gravity was not taking any effect I think. By there, there are several similarities kind of
connecting earth and space as the information truly was.

Surface is responsible for curvation of space, surface of planet for example, the curvation is responsible for falling, because near the surface of planet the surface is curved and flat at the same time, the space tends to take flet position, therefore pushes the matter down, there has to be a deepest study on this, this is just a hypothesis, but it seems more likely to be true about curvation and falling relation.