We live on a “dot planet”, Earth, the only planet in solar system where life exists. Sun is the ultimate source of energy for all existence on earth. The energy coming in the form of light from Sun is converted into chemical energy i.e food by the plants by photosynthesis. All the fossils fuels are derived from plants which existed millions of years ago. The existence of life on earth is dependent on sunlight.
The speed of light is 3*10^8 m/s. Sunlight takes around 8 minutes (precisely, 8 minutes 20 seconds) to reach earth. This means what we see Sun is its past view of 8 minutes. What we view is the past image of Sun which is the ultimate source of energy on earth. Many chemical reactions depends on sunlight which is necessary for survival. The fossil fuels like natural gas, coal etc. which takes million years of formation. These energy sources are created over a very long period of time from decayed and fossilized living matter, mainly plants and animals and the energy in these living matter originally came from Sun through photosynthesis. Sun is also responsible for changing weather pattern on earth. The existence of all forms of life on earth is fueled by sunlight, directly or indirectly.
Similarly, when we see Moon, it is 1.3 second past view of it as moonlight takes 1.3 seconds to reach earth. The speed of sound is 343 m/s. Although, the speed of sound depends on its medium of travel. When we speak, sound takes its own time to reach us. This means what we hear is past. Also, what we see is the past image including that of sun and moon. Our eyes also take some time to process the image.
Having said that, this raises an important question. Do we live in the present? We see the past and we hear the past. The ultimate source of energy on earth i.e sunlight takes 8 minutes to reach us. Our entire process is dependent on sunlight. Then do we live in present or in past. If we use telescope to see some planets of our solar system, we will see the past image and not the current one as light takes its time to reach us. If we see images of stars or planets of Milky Way Galaxy, we will see the past of it. Similarly, if some aliens will view our earth from their place of residence (assuming that there might be some habitable planet), they will see our past and not the present.
Consider an example. Planet Earth reflected its light which took 100 earth years to reach Planet X. Now Planet X people if use a telescope to focus on earth can see the light emitting from earth will be 100 years ago reflected by earth. Zooming in (assuming they have that high precision telescope), they will see us 100 years past image, meaning if it is 2021 on earth, they will be seeing 1921 earth. This will happen for us as well if we focus on say, Planet Y and light takes 50 years to travel to earth, then we will be seeing 50 years past of Planet Y. In fact, what we see in the night, the various twinkling stars, we are viewing their past light emitted from these stars, few years ago depending on the distance of those stars from earth. So is the case with sound. Space science had proved this that what we see is the past and not the present. This means that everything we see is the past and everything we hear is the past. Then how can we live in present? Do we really live in present?
Philosophically, we should try to live in present. But is it practically possible when everything going around happening is the past? This question might seem awkward, but I wanted to share with you all. You may have encountered or thought of this question. Hoping to get answer to this question. The answer to this question is subjective and can be debatable. Please share your views.