How long would it take for a human to walk one light year?

A light-year is approximately [math]10^{16}\rm{m}[/math] or ten trillion kilometres.

Human walking speed is about five kilometres per hour or, let's say, forty kilometres per day (allowing for eight hours walking, eight hours sleep, and eight hours contemplating the meaning of a long walk on each day).

That is going to take [math]\frac{10\,000}{40}=250[/math] billion days, or a bit less than a billion years (allowing for the occasional holiday at some of the places being passed).

About a fifth of the Earth's existence - thirty million human generations, and about five hundred times as long as the genus Homo has existed.

Dedicated human walkers could do it faster and, I dare say, the species at the end of those millions of generations would be considerably better walkers than the best Olympic walkers today.


Assuming we can walk about 2 mph. And assuming we go non-stop for sleep, meals, potty, etc,


One opinion : 225 million years

How Long Would It Take To Walk A Light-Year?


What would had happened if the earth did not revolve nor rotate?

There would be no day or night change, it would be either sunny all the time or dark all the time. One portion of the Earth would be unbearably hot and the other unbearabley cold, the only temperate zones would be on the fringes of the hot cold dividing line.

What are some of the monumental obstacles, that humans will have to overcome, in the coming years, if we are to survive as a species?

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If you were going to die tomorrow, where would you go?

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