Some scientists argue it may be too late to reverse climate change, and it's just a matter of time before the Earth becomes uninhabitable.
The recent movie Interstellar raised the notion that we may one day have to escape a dying planet. But is this even possible?
The laws of physics and the principles of engineering could go a long way to helping us answer this question.
Nature has given us a speed limit. We call it the speed of light - about 186,000 miles per second - and it is a hard upper limit on all relative speeds.
So, if it takes light one year to get somewhere, we can't possibly get there sooner than one year.
There is also the fact that the universe is big, really big. It takes light about eight minutes to get to our sun, three years to get to the next-nearest star, 27,000 years to get to the center of our own galaxy and more than 2,000,000 years to get to the next galaxy.
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