The cradle rocks above an abyss, and common sense tells us that our existence is but a brief crack of light between two eternities of darkness. -Vladimir Nabokov
Last Friday, I posed a question to you, and you kindly responded by voting as to whether, when you crossed the event horizon of a black hole, the lights would stay on or go off. The results so far?
You could be in a strong gravitational field, like exists near a black hole. Or, you could be accelerating due to your engines. Or — if you like your science with a little more fiction in it — you could be accelerating because you’re caught in a tractor beam.
No one doubts that the lights would stay on if you were simply accelerating, do they? Well, is crossing into the event horizon of a black hole any different?
Why don’t we ask Al. In 1907, two years after publishing his special theory of relativity, Einstein had what he would later call, “my happiest thought.” He had an insight that all accelerations were equivalent to an observer, regardless of what caused them and regardless of how fast the accelerations were.
He called this the principle of equivalence, and this is where we find our answer to the question.
It doesn’t matter how big your acceleration is or what causes it. It doesn’t matter what direction you accelerate in or how hostile your environment is. And, to give you the final answer, it doesn’t matter whether you’re inside of a black hole or not. As long as you still physically exist (i.e., you can neglect the tidal forces trying to tear you and your spaceship apart), the lights stay on!
And oddly enough, once you do cross the event horizon, if you want to maximize the time it takes for you to reach the center of the black hole, do you know what you should do to your ship’s engines? Turn them off completely! Any extra acceleration you put out, even if it’s directed perfectly away from the center of the black hole, will actually pull you in faster than if you turned all of your engines off. That’s, umm… a survival tip that could buy you precious extra seconds to get to the end of The Count of Monte Cristo. (Spoiler alert.)
All human wisdom is contained in these two words — wait and hope.
And that’s how you know that the lights stay on!