Time travel is currently only a thought experiment, but if you have to dream, dream big. Who hasn’t fantasized about going back in time to choose the winning lottery numbers, or to kill Hitler, or to say no to the prom date who drenched you in pig’s blood?

There ought to be a guide for time travelers. But in the fine tradition of 1950s nuclear safety movies, why have a guide when you can learn by fear? So here’s a look at what you can and should be afraid of in your time travels.

GETTING STUCK IN THE PAST/FUTURE

Because time travel is the stuff of science fiction and not fantasy, it likely requires some sensitive equipment to work. How sensitive? It needs to land you in both the right time and the right place (as well as the correct elevation, so that you won’t end up cemented inside a mountain). But as any Windows user can tell you, technology sometimes fails spectacularly.

And that’s the sort of thing that can leave you stranded where and when you least expect it.

If you’re sent to the past and your equipment craps out, most likely you’re absolutely and irrevocably stuck. After all, the raw ingredients that power your thingamawhatzit may not have been refined or even discovered yet. And your Uranium-235 might be able to let you witness the Crucifixion, but it’s no better than pound cake if it’s buried in a mountain along with your feet.

Now if your equipment fails in the future, you may actually have a shot at returning…if you can obtain the necessary requirements discreetly, of course. However, if the natives recognize you for what you are—a person born at the beginning of the computer age—be careful: you could be taken against your will and experimented on. After all, you still have the dregs of semi-unpolluted air in your lungs, and your brain can actually remember the feel of real sex. That makes you a valuable commodity.

Should you find yourself stuck in the past, it’d be a bummer knowing that Buffy the Vampire Slayer is forever out of reach. But let’s face it, that’s a million times better than life in the future—as a special exhibit in a zoo.

CHANGING THE UNIVERSE

Some time travel issues are more treacherous than others, and nothing is more fraught with peril than accidentally altering history. If you step off a predetermined path and crush a butterfly, time has a way of telling you that you should have joined PETA.

Think about it: every germy sneeze in the direction of a pregnant woman, every booze-fueled game of Russian Roulette with a stranger, you run the risk of altering the timeline. For every inconsequential moment, there’s a chance of turning all the intellectuals you know into fans of The Jersey Shore.

If your time travel device adheres to the Novikov Self-Consistency Principle (you can’t change history), then you’re good to commit mass Lepidoptera-cide. But even if your device allows for the consequences of your actions, it’s best to limit yourself to lurking in the shadows of historical events. If not, you could return to a world that seems eerily similar, yet for some strange reason your friends now call you Slappy.

CREATING PARALLEL UNIVERSES

One of time travel’s unintended consequences is the risk of creating a parallel universe. But there could be an upside to this: in one world, you can settle down and start a family, and in the other, you can be free to pursue your work.

Think about it. In one universe, you get to live the mindless existence of a parent to a newborn and in the other the mindless existence of an entrepreneur endlessly seeking funding. In each of these realities, you’d wonder if the choices you made were correct ones, causing major self-confidence issues. So, unsure of yourself, you fracture the universe again, creating all new worlds where you aren’t perpetually caught in traffic or where you always got the last donut of the day.

Unfortunately, no matter how many parallel universes you create, the sad fact is you’re still going wind up stuck on the 101, breathing in someone else’s exhaust fumes.

ENFORCED CHASTITY

In order to avoid sleeping with your eventual grandmother, thus creating a nasty paradox, time travelers should adhere to a strict abstinence policy. But like most humans, you’ll likely fall victim to those surging hormones known as the sex drive. ‘Cuz really, if there’s a choice between time travel versus sex with an attractive and willing partner, chemistry typically trumps physics.

But watch out. That busty barmaid or that handsome lad with a compound bow could be your great-grandparent. The cutie by the DNA-altering medispa? That’s your great-grandchild. So buckle up your chastity belt, because if you hit that, your offspring will be born with twelve toes and a horrific sense of self-loathing.

We exaggerate. Cousins can safely interbreed. It’s just icky.

CHANGING SOMEONE’S LIFE FOR THE WORSE

You may be restricted from changing the timeline in any way, but since you’re devious, you can try to get someone to change it for you. Of course, that, too, would be a mistake.

Revealing information about the past or the future can cause unforeseen results in the person you reveal the information to. Ask a new friend to buy stock in IBM in the year 1930. There’s no guarantee that he’ll do what you say. But if he does, who’s to stop him from taking the dividends for himself?

Think about it. Your actions can condemn your friend to getting rich and dying alone as he calls out in vain for the only things he’s ever loved: his sled and his slave-powered munitions factory.

IN CONCLUSION

So before you push the button that sends you into a time not your own, don’t. True, riches, glory, and revenge may beckon, but that there’s fool’s gold, son. The risks just may not be worth the reward.

Sure, you may be missing out on witnessing great events in history, but you can console yourself by knowing you’re already traveling through time…at exactly one second per second into the future.