At each moment, light (as well as electromagnetism and gravitational force) is coming towards you from every direction, in a sphere around you. The light has left its location at different times, from the Moon; 2 seconds ago, the Sun; 8 minutes ago, Vega; 25 years ago, Andromeda; 2 million years ago and so on. You could imagine a set of concentric spheres, each one containing a part of the universe you are experiencing. The greater the radius of the sphere, the farther back in time you experience that part. In the diagram this is represented as the “past light cone”; each ‘sphere’ becomes a circular slice of that cone. The present moment of each location in spacetime is the focused intersection or standing wave pattern of all waves and forces originating within the past light cone of that location. Likewise, all electromagnetic and gravitational waves and forces traveling into the future of the present are ‘dispersed’ relative to the observer by the inverse square law; intensity is proportional to 1/(distance²). For example, all the light the bounced off of a pterosaur 200 million years ago and passed through Earths atmosphere is still out there, traveling, 200 million light years away. It is incredibly diffuse, you would need to construct a telescope billions of light years across to create an image, but the information still exists.
For forces that travel at light speed, we only experience and effect the surface of the light cones. Matter, which travels at less than light speed through space, influences us and is effected by us within the volume of the light cones. All matter and forces travel at light speed, but in different dimensions. Light is restricted to space dimensions, and does not experience time. Matter travels at light speed primarily through time, and can also travel through space relative to other objects. To maintain light speed, matter will move less through time, giving rise to relativistic effects such as time dilation. Here I will cite "The Fabric of the Cosmos” by Brian Greene, an excellent book that shaped my thinking on this subject.
The implications of light cones are incredible. At each moment your body is being influenced by the volume of the entire universe, in a gradient from moments ago to the big bang. The size of the effect is mediated by the inverse square law, so the closest things effect you the most. However if one star in the andromeda galaxy, 2 million years ago, disappeared, there would be a minute change in the gravitational pull on the atoms of your body. Perhaps a salt ion in one of your neurons wouldn’t exit an ion channel, and your thoughts and life would be different. This effect goes forward into time as well, every action we take effects everything in out future light cone. As beings, we are completely integrated into the Universe, composed and created by every event in our past light cone, and manifesting everything in our future light cone.
