There is a distinction between the past, present and future. A case in point asking this question. Where were you when your parents ( or grandparents if you like ) were little? Everybody answers with the same conclusion. How could they exist at the time.

We all can not exist several years younger than we are now nor several years older we are going to be several years into the future. We can only exist at our current age in the now. The same could be said of our future children not born yet can not exist now until born several years into the future.

The same point with technology. In all of history technology today could not exist in the past. Take Microsoft history of the windows operating system. Windows 8 could not exist when windows 3x ( 3.0 )  was the latest system in the early 90's. Computer technology as a whole, in the now is drastically different ( or advanced if you like ) since then. And the technology to come doesn't exist  now until the future.

The future second has become the now and past second by the time you finish this sentence. It is clear every second travels from the future, present to the past. We measure clocks ( including digital time pieces ) in the present minute even though they are really only 60 second  periods in the present minute. The same with the future, past and present, hour, day, month, year, century, milliner,( thousand years ) million, or billion years. in fact period is made up of seconds of time.

Science and sports coaches make athletes win or lose by fraction of seconds in the now time while the rest of us tend to dismiss as to quick nick picking accuracy. We all hear TV motor sport commentators and car shows announce lap times and nose to tail following distance dramas less than a second  pronounced in decimals fractions. 0.25 is a quarter second, 0.33 is a third, 05 a half and 0.66 is two thirds and 0.75 is three quarter second considered quite critical.

Light is a time factor we measure the distance it travels in a second. It obeys Newton's first law of motion once set in motion continues in that motion indefinitely in light's case in the zero resistance of out of space coasting at a maximum speed limit that doesn't travel any faster.

It is a distance of just under three hundred thousand kilometers ( or a hundred and eighty thousand miles if you like ) by the time we say one thousand and one, the hand of analogue clocks moves a division, the second of digital time pieces and the time we walk a meter. In other words every one of those periods equals by the time  light travels just under three hundred thousand kilometers we can honestly call a light second: the distance light travels in second. Our mathematical instinct aggress in principle the maximum speed limit is mathematical constant which is symbolized c.

Despite the zero resistance of space it coasts no faster than the distance it travels per second. In out of space  it just doesn't the distanced any faster that amount of time every second. No matter how fast we travel light in out of space is always maxed out to three hundred thousand kilometers. ( Just under to be precise ).

In 1905 Albert Einstein realized star and planet gravities, ( as the atmospheres, the clouds of dust of nebulas and gas planets ) slows the passage of light. It takes longer to travel the same distance in the zero resistance of a vacuum. ( Deep space if you like ). The slower it goes the longer it takes to travel that distance. In other words if light was twice as slow it would travel three hundred thousand kilometers in two seconds ( Or a hundred and fity thousand kilometers in a second ).

When free of from resistance of the earth's gravity and atmosphere the distance traveled though the atmosphere closes. If twice as slow is anything to go by light accelerates and stops accelerating to its constant three hundred thousand kilometer per one second . In other words the faster light goes the faster it travels a distance and the slower it goes the slower covers a distance.

In other words entering the gravitational filed of earth's atmosphere slows light. Enough solidness stops dead in it's tracks. In less than a second it reverses direction traveling back out of the earth's atmosphere. The resistance gets less and less at more and more altitude. The distance becomes to maximum becomes shorter light speeding  back up finally reaching the maximum distance constant in out of space.

Light from the moon we see is nothing more than the origin of the sun's light deflecting an image of it like a straight mirror in the direction of earth. Although the moon varies in distance it is over a light second away. Our mathematical instinct agrees if we do some arithmetic on this taking less than a couple of seconds multiplied by c gives the us the distance. Our mathematical instinct recognizes the law of mathematics allows us to project with a known distance and c the seconds away.

Our instinct agrees at maximum coasting since there is sixty seconds in a minute traveling at a fixed distance every second the distance light travels in a minute is merely a simple calculation of sixty times c every second.  We can honestly say the distance light travels at maximum velocity in a minute is a light minute: the distance light travels in a minute. Our math's instinct will agree sixty light seconds of distance.

Light takes eight light minutes to reach our eyes from the sun. This means the sun is a distance of only eight light minutes away. In real time light is three hundred thousand kilometers above the sun's surface by the time you finish this sentence. We don't see this light till eight minutes into the future. Our mathematical instinct agrees the distance from the sun to earth ( in terms of kilometers or miles what ever you prefer ) is sixty times eight times c.

Current light we see every second is nothing more than light's image of the sun as it was eight minutes ago every second. It is three hundred thousand kilometers ( or a hundred and eighty six thousand miles if you like ) away from earth by the time you finish this sentence every second of time as well.

Our mathematical instinct agrees the fixed constant is sixty times sixty ( or sixty squared ) equals three thousand six hundred seconds times c the distance light travels travels by the time a one hour TV program.

Clocks change the western calendar date every twelve midnight. Our mathematical instinct agrees if we start with the first second past midnight to the date changes again is sixty squared times twenty four giving us a total of every eighty six thousand four hundred seconds the date changes. The distance light travels in that time is all those seconds times c.

In other words every time clocks changes the date is eighty six thousand four hundred periods additions of a fixed distance distance of just under three hundred thousand kilometers of time.

Mathematics tells our math's instinct the reciprocal of c every second is eighty six thousand four hundredth of the date change period. Our math's instincts agrees proof when we muiltiply a hundred and eighty six thousandth by a hundred and eighty six thousand equals one a date change period. In other words a light day.

We can project from known distances the planet of our solar we can project them in light days away at light speed.

Operating on the same principle we can add up the first second twelve midnight Monday morning though every day of the week to the first second of the following twelve midnight Monday morning times c the distance light travels in a week. In other words a light week. We can project from known distances planet of the our solar system in terms of weeks away at light speed.

The western calendar divides up mouths into different days. They vary from as little as twenty eight to as much as thirty one. We are open to project how many moths a planet of our solar system is away at light speed.

However our mathematical instinct whole heartily agrees we can project all the seconds in a year by sixty squared times twenty four times three hundred and sixty five days of the year. Times c projects the distance. ( In terms of kilometers or miles which every is preferred ).We end up with a figure over thirty one million seconds the distance light travels familiarly known to all of us as a light year.

Calculating for the distance light travels in a decade we need to take into account of the extra day at the end of every February every third leap year. Taking into account of all the leap years in a decade we can deduce the distance in years the equivalent light years, light travels in a period of a decade.

Operating on the principle we can deduce the years equivalent of light years the distance light travels in a century, a milliner ( a thousand years ), a million years, a billion even trillions of centuries of time passes on earth. The earth is only a little more than several million centuries old. Those into challenging mathematics can convert years to centuries and vice versa centuries to years of time passes on earth.

The point of the first light from the big bang that has supposed to have created our universe is only just over fourteen and a half light years away from earth. Those into challenging math's can challenge themselves to work the time of the big bang in terms of  in simple equivalent years converting to centuries to the astronomical unit parsecs.

In the meantime we can only ponder on how far away from earth the opposite direction away light has traveled from earth. For all we know it may have already reached equal distance away ages ago.