We all know that time has direction, because we've all experienced it; you will never again be as young, for example, as you are at this very second. Or this second. Or this second. The directionality of time prohibits it.
But according to the laws of physics, there is no intrinsic difference between the past and the future; how we experience time, and distinguish between what happened last week and what may happen tomorrow, is what is known as an "emergent feature." And yet, it's our ability to experience the directionality of time that allows us to make sense of the world around us, up to and including the origins of the universe.
But here's the bit that's really mind blowing. According to Cal Tech physicist Sean Carroll — guest narrator for this week's Minute Physics, featured up top — it is by understanding the origins of the Universe that we'll come to truly understand the directionality of time, that we used to make sense of the Universe in the first place. [Minute Physics]