Time travel is a great concept — but how do you show it happening? This weekend's Looper picks a pretty simple way of showing gangsters jumping through time, but we've also seen kids in time-traveling spaceships, portal-jumping bandits, and a hot tub that lets you relive your past.

We're used to seeing lots of fantasy picture books aimed at little kids — so it's nice to find a bunch that are more geared towards science fiction. Check out a look at some new science fiction picture books... plus one classic.

We take it for granted that the past is fixed. History always happened the way we remember it happening. But how do we know for sure that that's the case? If time travel is possible, time travelers could be zipping back and changing things around all the time. How would we even be able to tell if that was the case?

Art student Dan Henriksson built this gorgeous representation of a time machine using arduino circuit boards and a CNC milling machine. This is geek DiY ingenuity mixed with science fiction art.

We've seen the raunchy trailers and learned the sad backstories of our midlife crises time travelers, now it's time to witness the first red band clip. Watch what lead to the eventual hot tub time portal.

The brand-new redband Hot Tub Time Machine trailer is out, and it's stuffed with filth, 1980s ski sluts, grown men crying, and sex. Also, it finally answers the burning question: How can 44-year-old John Cusack score with 18-year-old ladies? NSFW.

In honor of Moon, opening today, we went kinda loony (get it?) coming up with our favorite lunar scenes in film and TV. (We restricted the list to our own planet's moon; sorry, Saturn and Endor fans.) Watch them here.