Going back in time is a common science fiction/fantasy scenario. Sci-fi depictions of time travel often feature elaborate and unbelievable contraptions, from a souped-up Delorean in Back to the Future to a Victorian plush velvet reclining chair in H.G. Wells’ The Time Machine.
But, what if turning time’s arrow backward is as simple as understanding scrambled eggs, coffee, and entangled particles?
1. Time As A One-Way Street
“Time’s Arrow” was the term astrophysicist Arthur Eddington coined in 1927. It is a theory, so far unchallenged, that time only has one direction – forward. It’s often raised as the reason time travel is impossible. Since time can only move in one direction, we cannot rewind it back to relive moments of the past. More than just a theory, the arrow of time is based on one of the most important laws of physics.
2. A Physical Law Forbids Time Reversal. Or Does It?
Eddington based his concept of Time’s Arrow on the second law of thermodynamics. In physics, the concepts of time and energy are interrelated due to the natural state of disorder. This basically means that as one travels forward in time disorder increases, and that going forward is the only choice.
3. Cream, One Sugar, And A Swirl Of Disorder
This is complex stuff for anyone to wrap their head around, so here’s an example of how disorder is part of our every day lives. Consider a morning cup of joe. What if you add creamer to a cup and start stirring, but then remember you wanted to have it black? You cannot unmix the coffee and cream – they are now in a disordered state. And what about your breakfast plate?
4. Disorderly Eggs Prove A Point
Another example is a plate of scrambled eggs. A fresh new egg is in a low state of disorder. When you crack the egg it is in a higher state of disorder. Take it a step further, and scrambled eggs are very disordered. You cannot unscramble eggs, and they certainly do not unscramble spontaneously.