# Bending space and space time - what is the difference?

• Premanand
In summary, the conversation discusses the concept of space-time curvature and its effects on gravitational forces. The participants also address the difference between "bent space" and "bent time" and how they are interconnected. They also mention that adding mass can increase the curvature of space and time, and how this affects our perception and experiences. The conversation also touches on the different types of curvature and how it relates to gravity and our understanding of the universe.
Premanand
Sorry... This question may be very basic. As a self taught, I understand that the mass will bend the space around it such that any other mass entering the bent space will immediately be pushed towards the center because of the bent space. Higher the mass, higher will be the bent (if that is the right word)... and since speed of light is constant, the 'experience' will also vary accordingly as all our nerves and all other biological activity happens by electromagnetic waves... Thus, time and space are interconnected... However, can I just say that space gets bent by presence of mass... Because somewhere I read that it is incorrect to say space gets bent because it is the space time that is bent... What is the difference? Because to me adding mass to bend the space is perfectly OK and time is just a side effect of it.

Premanand said:
What is the difference?
Space time curvature has a very precise meaning and it is perfectly possible to have a curved space time with a flat space. GR is about curved space-time, not about curved space. Space may be curved as well, but you reqlly cannot neglect the time part.

Premanand said:
Because to me adding mass to bend the space is perfectly OK and time is just a side effect of it.
Then you would be wrong.

Orodruin said:
Space time curvature has a very precise meaning and it is perfectly possible to have a curved space time with a flat space. GR is about curved space-time, not about curved space. Space may be curved as well, but you reqlly cannot neglect the time part.Then you would be wrong.
Thank you... Could u answer one more question please? Does adding mass to the object bends the space? Is the bent space a reason for increase in force of attraction when mass is increased?

Premanand said:
Sorry... This question may be very basic. As a self taught, I understand that the mass will bend the space around it such that any other mass entering the bent space will immediately be pushed towards the center because of the bent space. Higher the mass, higher will be the bent (if that is the right word)... and since speed of light is constant, the 'experience' will also vary accordingly as all our nerves and all other biological activity happens by electromagnetic waves... Thus, time and space are interconnected... However, can I just say that space gets bent by presence of mass... Because somewhere I read that it is incorrect to say space gets bent because it is the space time that is bent... What is the difference? Because to me adding mass to bend the space is perfectly OK and time is just a side effect of it.
It is possible to imagine "bent space" without "bent time" (note that these expressions refer to the mathematics). If you have the concept that "bent time" is a necessary effect of "bent space" then the result is the same.

Premanand
harrylin said:
It is possible to imagine "bent space" without "bent time" (note that these expressions refer to the mathematics). If you have the concept that "bent time" is a necessary effect of "bent space" then the result is the same.
Thank you... So on conceptual level... I can bend the space further by adding more mass? ... I mean adding mass increases 'the force of attraction' by bending the space 'more' ?

Premanand said:
I mean adding mass increases 'the force of attraction' by bending the space 'more' ?
No, the effect of "attraction" is mostly related to the time distortion (gravitational time dilation). The spatial curvature only causes minor effects. See link in my previous post.

Premanand
As you posted, time and space ARE interconnected...here are a few insights.

You can picture the paths of a particle as curves in special relativity as you would curves on a flat graph paper. SR involves relative motion and relative time,and one type of curvature but not gravity. When gravitational curvature is involved, as in general relativity the graph paper itself on which the curved paths are drawn is itself curved. That's not obvious and is why it took an 'Einstein' to figure it out.

In general, when relative motion and mass is involved, both space and time are distorted, that is, 'bent' or 'curved'. And there are lots of types of curvature!

Premanand said:
Higher the mass, higher will be the bent (if that is the right word)... and since speed of light is constant, the 'experience' will also vary accordingly as all our nerves and all other biological activity happens by electromagnetic waves... Thus, time and space are interconnected..

yes space and time ARE interconnected. But don't think 'experience' is all about electromagnetic waves, or light. If you bump your head on a door in the dark, there are no electromagnetic waves, but you'll not like that experience, right? And what about loud firecrackers...those are SOUND waves [air molecules hitting your eardrum] not electromagnetic waves and you might not like those either; but music, now those are nicer sound waves. And don't forget about taste and smell either..not electromagnetic in nature.

As already noted 'curvature' of space and time often goes together. One way I have found to think about 'distortion' of time is that near big masses, lots of gravity, time is 'distorted' a lot. Time runs slower in higher gravity [potential] when viewed from a distance. Another way to think about curvature or distortion is to remember there are three dimensions of space [up/down,left/right, in/out, or x,y,z]; by analogy just think of time as a fourth component and you have 'spacetime'...and all four components can be 'curved'.

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Finny said:
And don't forget about taste and smell either..not electromagnetic in nature.
(My emphasis)
Careful here, while not electromagnetic waves, all of the phenomena which are mentioned here are mainly electromagnetic in nature, just like all forces we experience on the molecular level. If not for the electromagnetic force, air molecules hitting an eardrum would pass right through it. From when you go away from internuclear forces to when you arrive at scales at which gravity plays a role, all forces are electromagnetic in nature.

Finny

## What is the difference between bending space and bending space-time?

Bending space refers to the idea that objects with mass can cause distortions in the fabric of space, creating a curvature that affects the path of other objects. Bending space-time, on the other hand, takes into account the fact that the fabric of space and time are interconnected, and mass can also cause distortions in time. Essentially, bending space-time involves both the curvature of space and the warping of time.

## How is space and space-time bending possible?

According to Einstein's theory of general relativity, mass and energy can cause the fabric of space-time to curve. This is due to the principle that mass and energy are equivalent, and therefore can affect the geometry of space and time. The more massive an object is, the greater its gravitational pull and the more it will bend the fabric of space-time.

## What are some real-life examples of space and space-time bending?

One of the most famous examples is the bending of light around massive objects, such as stars. This was observed during a solar eclipse in 1919 and is now used to study distant galaxies. Another example is the slowing down of time near massive objects, known as gravitational time dilation. This has been observed in experiments using atomic clocks.

## Can we control or manipulate space and space-time bending?

Currently, we do not have the technology or understanding to intentionally manipulate space and space-time bending. However, scientists are researching the possibility of creating artificial gravitational fields and manipulating the fabric of space-time for practical applications, such as faster space travel.

## What are the implications of understanding space and space-time bending?

The understanding of space and space-time bending has led to a deeper understanding of the universe and has revolutionized our understanding of gravity. It has also opened up possibilities for advanced technologies and future space exploration. Additionally, it has helped to confirm and further develop Einstein's theory of general relativity, which has had a profound impact on modern physics.

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