# Exploring Spacetime Curvature and Light

• Isaac0427
In summary, according to GR, energy (both light and mass) bends spacetime and light is also affected by spacetime curvature. The exact effects of this curvature on light's movement and dynamics, other than gravitational lensing, are not fully understood as there is no perspective of light.
Isaac0427
Hi,
So according to GR, energy bends spacetime, right? So that would include both light and mass. If I am understanding this right, light bends spacetime, and is also affected by the spacetime curvature. Could someone explain exactly what the spacetime curvature does to light (I mean like how it affects the movement and dynamics of light, not gravitational lensing). Thanks in advance!

Isaac0427 said:
Hi,
So according to GR, energy bends spacetime, right? So that would include both light and mass. If I am understanding this right, light bends spacetime, and is also affected by the spacetime curvature. Could someone explain exactly what the spacetime curvature does to light (I mean like how it affects the movement and dynamics of light, not gravitational lensing). Thanks in advance!
Probably you should clarify better what you would like to hear, for gravitational lensing is an important aspect of how space-time "curvature" affects "the movement and dynamics" of light...

I am not sure what you mean by "I mean like how it affects the movement and dynamics of light, not gravitational lensing". Gravitational lensing is a result of gravity affecting the movement and dynamics of light! Light moves along geodesics in space.

HallsofIvy said:
Light moves along geodesics in space.
In spacetime.

vanhees71
Right, thanks.

HallsofIvy said:
I am not sure what you mean by "I mean like how it affects the movement and dynamics of light, not gravitational lensing". Gravitational lensing is a result of gravity affecting the movement and dynamics of light! Light moves along geodesics in space.
Like how it affects the speed of light, or how light travels from light's perspective. Not just how light looks to us near an object with a lot of mass.

A.T. said:
What?
From your perspective if you were light. But I understand it now.

An important point in relativity is that there is no such thing as the perspective of light. It is never possible to be moving alongside a light ray, and trying to work out what would happen if you did do that impossible thing always leads to contradiction and confusion.

Isaac0427

## 1. What is spacetime curvature?

Spacetime curvature is a concept in physics that describes how the presence of mass and energy can bend the fabric of spacetime. This bending is what causes objects to move towards each other under the force of gravity.

## 2. How does light behave in curved spacetime?

In curved spacetime, light follows the curvature of space and time, causing it to appear to bend as it travels through space. This is known as gravitational lensing and is a key piece of evidence for the theory of general relativity.

## 3. What is the relationship between spacetime curvature and the curvature of space?

Spacetime curvature and the curvature of space are closely related, but they are not the same thing. Spacetime curvature describes the overall curvature of both space and time caused by the presence of mass and energy, while the curvature of space refers specifically to how space itself is curved.

## 4. How does the presence of mass and energy affect spacetime curvature?

According to the theory of general relativity, mass and energy are what cause spacetime to curve. The more mass and energy that is present, the greater the curvature of spacetime will be. This is why massive objects like planets and stars have a significant effect on the curvature of spacetime.

## 5. Can we observe the effects of spacetime curvature in our everyday lives?

Yes, we can observe the effects of spacetime curvature in our everyday lives. The most well-known example is the force of gravity, which is a result of the curvature of spacetime caused by massive objects. Additionally, GPS technology relies on precise calculations of spacetime curvature in order to accurately determine location and time.

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