Will we ever reach the nearest star, Alpha Centauri? How about walking?
Hard to Imagine
What is a light year?
It's not a measure of time. It's a measure of distance; the distance that light travels in a year.
How far is that?
Well, to get that answer we must multiply the number of seconds in a year (31,557,600) by the speed of light expressed in seconds (186,000 miles or 300,000 km.). The answer is 5,869,713,600,000 miles (9,467,7280,000,000 km.). So, you can see why astronomers prefer to use a light year as the unit of measurement.
The Moon is about 240,000 miles away (380,000 km.). Divide that by the speed of light per second and we get 1.3. So, it takes light about 1.3 seconds to get there from the Earth, or we could say the distance to the Moon is 1.3 light seconds.
The average distance of the Earth from the Sun is roughly 93,000,000 miles. How long does it take light to travel from the Sun to the Earth? Dividing that distance (93,000,000 miles) by the speed of light per second gets 500. Thus, it takes light 500 seconds to reach the Earth or 8 minutes and 20 seconds. The Sun is 8.3 light minutes from us.
Alpha Centauri, the nearest star not counting the Sun, is 4.3 light years distant.
How far has the human species walked if you calculate it in a straight line without any interruptions for sleep and rest?
Modern Homo Sapiens has been around for about 160,000 years, or 900,000 years if you include the Archaic types. Beyond 900,000 would be Homo Erectus.
There are 8,766 hours in a year. Multiply 160,000 years of existence by 8,766 hours. We get 1,402,560,000 hours of walking. Multiply this by a walking speed of 3 miles an hour and we would cover 4,207,680,000 miles by walking non-stop. Rounding it off to 4.2 billion miles makes it farther than the 2.8 billion miles to the farthest planet Neptune. We’ve left the solar system, but still far from Alpha Centauri.
What about including the Archaics? Doing the math, we get 23,668,200,000 miles of walking. Rounding this off to 24 billion miles and it’s nowhere near Alpha Centauri's distance of 25 trillion miles. We would be only one thousandth of the way there after walking for 900,000 years.
So, how fast would our ancestor need to have been speeding for 160,000 years to be reaching Alpha Centauri just about now? The answer is 18,000 miles (28,800 km.) an hour.