Here's a general explanation of how photons are affected by gravity:
Gravitational Lensing: When light passes near massive objects, such as stars, galaxies, or black holes, the gravity of these objects can cause a bending or distortion in the path of the light. This effect, known as gravitational lensing, is a consequence of the curvature of spacetime induced by the presence of mass. The more massive the object, the stronger the gravitational lensing it produces.
Gravitational Redshift: When photons travel through a gravitational field, their frequency or energy can change. As photons move towards a region with a stronger gravitational field, they lose energy, resulting in a shift of their frequency towards the red end of the spectrum. This phenomenon is called gravitational redshift. Conversely, photons climbing out of a gravitational field gain energy and undergo a shift towards the blue end of the spectrum, known as gravitational blueshift.
Gravitational Time Dilation: According to the theory of general relativity, the presence of gravity can slow down the passage of time. This phenomenon is known as gravitational time dilation. Photons, like all other particles, are affected by time dilation. As they travel through a strong gravitational field, time slows down for them, leading to a stretching or expansion in their wavelength. This effect contributes to the gravitational redshift of photons.
In summary, while photons are massless particles, their energy and momentum allow them to be influenced by gravity. The effects of gravity on photons are observed as gravitational lensing, gravitational redshift, and gravitational time dilation. These phenomena play a significant role in various astrophysical observations and have been experimentally verified, supporting the predictions of general relativity.
