Here's a breakdown:
* Massless: While photons don't have rest mass, they still have energy and momentum. This is a fundamental aspect of their nature as electromagnetic radiation.
* Stationary: It's important to note that photons cannot be truly "stationary" in the traditional sense. As massless particles, they always travel at the speed of light.
* Gravity's Interaction: Gravity is not solely a force that acts on mass. It's actually a curvature of spacetime caused by the presence of mass and energy. Since photons carry energy, they contribute to this curvature.
How it manifests:
* Gravitational Lensing: Light from distant objects bends around massive objects (like galaxies or black holes), effectively acting as a lens. This bending is due to the gravitational curvature of spacetime caused by the massive object.
* Gravitational Redshift: Photons traveling in a strong gravitational field lose energy, causing a shift towards longer wavelengths (redshift). This is another manifestation of the interaction between photons and gravity.
In summary:
Photons interact with gravity because they carry energy, and gravity is fundamentally about the curvature of spacetime due to mass and energy. Even though photons are massless, their energy still contributes to this curvature, leading to observable effects like gravitational lensing and redshift.
