I was thinking to learn how to build a Clipper ship and a strong working knowledge of navigation by the stars (along with sextant and compass). Think how far these things would go in opening up the world and furthering the Empire.
And while you’re at it, take back a working knowledge of how to make pasta and pizza and speed things up a bit for them. Then buy up the future site of the Vatican and will the deed to your dependents…
THIS IS THE TIME PATROL. THIS IS YOUR ONLY WARNING. CEASE AND DISSIST IMMEDIATELY. IF YOU FAIL TO DO SO, WE WILL TAKE THE NECCESARY ACTION AGAINST YOUR GREAT-GRANDFATHER.
Time Patrol out.
Shit, if all you want to do is get rich, then bring back some coca plants and become a crack merchant.
Just call me “Pimpus Daddius.”
how do we know time travel hasnt already fucked up history through schemes such as this? there’s so many things that just make no sense when you think about them.
Give them knowledge of improved bridles. Roman horses could pull only about five hundred pounds because of the poor design of their horse collars. Medieval horses could pull up to three thousand because of improved design. I’m not sure how well that would be recieved, since slaves did the heavy pulling, but it’s worth a shot.
Ships wouldn’t be a good idea - the Romans were unapologetically landlubbers. When they did sea battles, they often used the ‘corvus’ - essentially, a plank with spikes on the bottom. They’d park their ships right next to the enemy, lower the corvus, which would latch onto the enemy ship and act as a bridge for the soldier aboard to fight on their own terms.
Me, I’d introduce the corvus, if it wasn’t already invented, if only for the cool name.
Introduce the longbow and the crossbow. It worked wonders against the mounted and heavily-armored French at Agincourt (okay, really bad weather helped the English, too) - imagine what it would do against foot soldiers. Armor sucked at the time - you probably could pierce it with a spitball. While longbows require loads of strength to operate, they’re very effective at picking off soldiers, armored or not. Crossbows are a lot harder to make and have poor range, but they can be used even by weaklings like me.
Issues
What a wonderful question! There is so much to say about it!
It would really be quite difficult to bring either knowledge or items back to Classical times.
You will have difficulty with culture and the knowledge frame-set. For instance, Greek mathematics was closer to a religion – if you went to Pythagoras and started discussing mathematical issues he might want you killed as a punishment for revealing secrets. Remember he had Hippasus drowned for discovering irrational numbers. That’s if he understood you. It’s most likely he wouldn’t, even if you spoke perfect Greek.
To understand why, look at Aristotle’s explanation of force transmission. We think in, and use, Newtonian terms. He did not. As well as learning Latin and Greek, you would have to fit yourself into a frame of thought where ‘transmission of force’ translates as ‘propagation of species’, which sounds like biology. Classical physics operated with a fundamentally different approach to ours – objects moved or existed because it was ‘in their nature’ to do so. You can see that, without very specialist study of classical science and local cultural mores, you would be in the position of knowing more than them, but being unable to put it over.
I don’t think you could make a living calculating either - there was not the same stress on data for engineering, so there was less raw material for computers (the people, not the machines). There were, for instance, no standards for force measurement.
It is instructive to look at the experiences of people who lived in those days (or these days!) who have new and different ideas. They tended to get locked away, or worse. To succeed in a culture you have to fit in. And that means not being too far removed, or annoying the local establishment too much.
Even military hardware might be difficult to sell. Look at the submarine. The British didn’t encourage it because it was ‘unsporting’, and that was only a hundred years ago. Total War existed in classical times but was different – there would be no glory in using a machine gun from a hole in the ground, so a local military leader might reject modern weaponry for cultural reasons.
So perhaps, if there is so much difficulty working with a different culture, you might want to reject it and run on your own as a bandit? Modern weaponry would certainly give you an edge, but what would your modern immune system do? Smallpox, plague and cholera were much more common, possibly with other unknown diseases. I don’t know if modern vaccines would be effective against 2000-year-old diseases. And I suspect the modern bugs you bring with you would prove much more effective in killing the local people than any weapon you could carry.
Assuming you survive the local bugs, Art might be an effective cross-cultural item to trade. The only difficulty we have here is that classical art was a lot better than ours, so the interchange would be a bit one-way.
L. Sprague de Camp wrote a time-travel story about this, too. A Brookhaven physicist invents a time machine a goes back in time to correct Aristotle’s ideas in the story “A Gun for Aristotle”. Disastrous results, of course.
Amaze everyone with your ability to read silently. No, really- even the educated classes usually read aloud to themselves. There’s a bit in Augustine’s Confessions where he marvels at Ambrose reading silently.
But that won’t make any money.
Figure out how to make a working adhesive out of local materials, and invent band-aids. Try to get the ladies to stop using lead-based makeup. Learn how to make fine-quality soap- I don’t think they had it. If you’re artistic, introduce 3-D drawing.
take back some rubber plants. Keeps us dry, makes travel confortable, can be done using low technology. Just make sure that you aren’t burnt for witchcraft
I’d want to take back a good working knowledge of medicine and surgery, along with a decent supply of antibiotics and painkillers. You’d be invaluable and inexpendible.
That, a few good guns, and a helluva lot of ammo. I would hide most of it away but carry an easy concealable handgun like a walther ppk.
Must have been:
Proof that coffee can make one rich:*
*besides Starbucks
Longbows wouldn’t work well. The technology is pretty simple, but Asimov was able to make the case that the English were the first people sociologically capable of effectively using the longbow.
The idea is that to make them effective, you need large numbers of folks using them, and all of those folks had to be extensively (and expensively) trained. The numbers required meant that bowmen had to be commoners, but the training made them non-expendable, and non-expendable commoners was an idea completely alien to most military thought prior to the English.
If you’re still planning on taking something back that’ll make you rich, how about pins or nails or something else that was handmade and expensive back then, but is cheap now? Glass beads, buttons, very fine chain or wire… you’d need a lot, and I think knowledge is still the best way to go, but oh, well…
Even simpler than the antibiotic thing- study medicine, then go back and wash your hands between cases. You’ll be famous as the person who’s patients don’t die.
Why bother concealing it? The Romans wouldn’t recognize a handgun if you hung it from a necklace. You could just carry a Desert Eagle around.
Heck, that would solve a lot of the culture barriers, wouldn’t it? If people’s heads start exploding whenever they attack you for heresy, your social standing would shoot up 'REAL quick.
Can anyone here translate “This…is my BOOM STICK!” into Latin?
Ranchoth
Cervaise has got it exactly right. Addictive drugs. Those Roman upper classes are famous for their partying.
Marijuana is not really that addictive. Can you grow coca, poppies or tobacco in Rome? You’d have to bring an initial supply large enough to hold you over until you can grow the plants and process the end product.
Err, about being the best darned doctor this side of the Tiber…
I heard a story a long time ago about a particular Roman doctor who was forced to give up his practice because he was so successful at keeping his patients alive that he was said to have cheated Hades (well, Pluto, but they’re basically the same God, having gone through the name-change bureau). I don’t know how true this is, but I wouldn’t put it past the Romans, or almost any people at the time.
Maybe saunter off to India? I hear they had flying machines and nuclear weapons around that time :).
Armor wasn’t any worse than that of most of the middle ages: they had chain mail (lorica hamata), scale armor (lorica squamata), and armor made of segmented plates (lorica segmentata). They also wore greaves and well-made helmets. The chief weapon was the spear or javelin; only after they’d mowed down a few ranks did they then close in and use the gladius (the short sword).
You might be able to persuade the mounted legions to adopt the stirrup, which otherwise wouldn’t show up in Europe until the invasion of the Huns.
“habeo boom-stick!”
funney!
And the thought of a Caligula style bachanalia with the Emp on X is just amusing as well… although in a totally icky way.
Hmmmmm…
Knowledge about China, India, Africa, and the nations and politics in those regions might come in handy. Set yourself up as a gentleman adventurer of some sort.
They already had opiates from Asia Minor.
BTW, they also already had a form of pizza (a wheel of bread covered with meat and cheese), not to mention hamburgers, hotdogs, and fast-food shops to serve them. Clever bunch, those Romans. 
As far as the plebian/Roman citizen question, several cities in Italia were granted citizenship (Pompeii is one example). Claim to be a plebian from one of those–but you’ll have to bluff it out if anyone inquires as to who your patron was ‘back home.’
I think your best bets are medicine, as stated before by others, or real estate: take back enough gold to buy a property and build an upscale apartment house. If you install a never-before-heard of contrivance, the fireplace for cooking and heating, into your apartments, your building is at a lesser risk for fire. If you go for medicine, be sure to learn herbal medicine for those patients who will want a simple tincture of chamomile or valerian.
I read the thread twice, and I didn’t see mention of a printing press. Or, more correctly, bringing back the tools and knowledge needed to make printing presses and paper (there was mention of paper, in reference to Lest Darkness Fall).