Mick's Muses's

Most people understand that light travels at a fantastic speed, about 186,000 miles per second. This means the furthest that can be see, even with the most powerful of telescopes, is some 13.7 billion light years away. This is known as the observable universe. Anything beyond that distance simply cannot be seen, because any light beyond that point will not have sufficient time to reach us.

Sometimes it is a bit mind-boggling to comprehend such vast distances, but if we think in more parochial terms of just our own solar system, we know it takes about 8 minutes for the light emitted from our sun to reach us. That means when we look into the sky during the daytime, the clouds we see are being illuminated by light that is already 8 minutes old, the same as any object we see on the earth.

Condensing these figures into broad understandable terms, it means that if you hold your hand about one foot in front of your face, it takes the light reflected from your hand, about one billionth of a second, known as one Nanosecond to reach your eyes. Although for all intents and purposes we would consider this instantaneous, it still means that a given amount of time has elapsed between the moment you looked at your hand, and before the reflected light from your hand reached your eye. Technically that is now in the past and not the present.

It does not matter what you look at, or how close to your eye something is, a given amount of infinitesimal time will have elapsed before the light reaches your eye.

This means that technically we can never see the present, only the past.

Filed under: Uncategorized, We can never see the present | Tagged: Nanosecond, Past and Present, speed of light, time |