The life long journey is really long. During my 67 years I have traveled a distance nearly 2 trillion kilometers. Here is the math.

They say life is about the journey, not the destination. That got me thinking about my life long journey in objective terms. After celebrating my birthday last week, I got to wondering about the distance my life long journey had covered.

So, let’s do the math.

Start with walking. Averaging more than 7,500 steps a day, in 67 years I have taken perhaps 200 million steps. That adds up to around 160 thousand kilometers distance just walking around.

Then, the planet, solar system, galaxy and universe took me for a ride. During my life long journey, this really adds up.

- At my typical latitude, I have traveled 2.1 million kilometers as Earth rotates.
- Once a year Earth travels 960 million kilometers orbiting the Sun. After 67 years, I have traveled 6.4 x 10
^{10}kilometers through the Solar System. - Meanwhile, the Solar System revolves around the Milky Way. Add another 500 billion kilometers.
- Finally, our galaxy moves 20 billion kilometers through the Universe each year. So, my total journey through the Universe during 67 years sums to 1.3 x 10
^{12}(trillion) kilometers.

So, this idea of life being a journey really has legs. Since birth, I have traveled close to 2 trillion kilometers. If you are my age, so have you! Check out this video about how fast we are traveling.

## Life Long Journey – Keeping Track of Time

Time is probably our oldest measurement. Pretty amazing, given that time is entirely abstract. The earliest time keeping was done with calendars, and they were lunar rather than solar. This lasted about 6,000 years before the Romans switched calendars to the sun. Clocks arrived around 1500 BC using sundials and water-flow. These gave way to mechanical clocks in the 11^{th} Century. Up to the 14^{th} century we were happy with knowing just hours. It took another 200 years to get down to minutes and seconds.

Today we have atomic clocks measuring minute increments of time and remaining accurate for 100 million years. At least, so we are told.

The human journey is one of space and time. But the sad part is that I have spent 20 years sleeping. And, if we lived on Mars, with its slower orbital period, I would only be 35 years old!