Antibiotics and lots of them. Medical books. A life time supply of contact lenses and a couple pairs of glasses. Dental tools & a book on how to use them, and, to make friends and influence people: cigarettes, candy and nylon stockings.

Latin dictionary.

I think you'd meet mostly with befuddlement with the cigarettes and stockings.

standard carry-on dimensions

Carry-on what? What am I traveling in/on? If it's a time machine, I would like to keep it so I can travel back to this time and have electricity. Unless...can I bring electricity? Because I would really like to have electricity.

And stuff to plug into the electricity.

Comic books from the 1970's. No reason I should be any more prepared to deal with life or have any special advantages since I can't be fucked to do anything like that in the modern era.

If history has taught us anything it's that you have to time travel naked.

Nothing. I'd save all space in the carry-on for bringing stuff back.

Maybe a video camera.

I'd carry a set of history books and set myself up as a prophet. License to print money, as long as I didn't get myself killed. Which you know I would.

Oh, I missed the 'permanently'.

chocolate.

mygothlaundry has the right idea. Of course, I'd add a comprehensive history of the times, and a very detailed historical atlas.

Maybe add a gun and some light steel stock?

Condoms, so I don't get pregnant from all the orgies.

Sheep gut would be locally available.

A history of early Rome would be nice. As a prodigy, you might be introduced to people in power, and it would be nice to know who to associate with.

I'm sort of assuming the time-travel process has taught you latin.

Yeah, antibiotics, medical books, and dental stuff. Books on things like engineering and mechanical technology and history. Gold, spices, gems? A seriously good compass. Acid-free paper for recording stuff and fountain pens (can make more ink when you run out.)

I also agree with mygothlaundry (and carter - although I suspect that the local language could be sussed eventually) but with some minor differences.

In the vein of the medical books, I'd introduce septic theory (ala Pasteur's experiments). Instead of antibiotics, pure specimens of various bacteria that produce various antibiotics (so I can renew my supply) and basic equipment to isolate said antibiotics. Not only will you be able to take care of yourself, you'd also have a valuable service/goods that you can trade.

Chemistry books would be useful, too.

Also, less practical for me since I have little skill in the area (as opposed to biology/chemistry) - books describing metallurgy and geology (how to identify iron ore, coal deposits, and how to smelt iron ore and alloy it into steel) for additional service/goods that can be traded (think "transparant alumininium" from ST4).

Considering that if you filled a full-size carry on with gold, you'd have a brick weighing a good fraction of a ton (around 875 kg/1925 lbs by my figuring), I'd have to say a suitcase full of either cloves or cinnamon.

Seeds are an awfully tempting idea though. Tomatoes, potatoes and modern cross breads like frost-tolerant wheat and canola could be really useful. Would chocolate, coffee or tea grow in the Mediterranean?

Shouldn't someone bring up the whole "if you alter the past by improving Roman Science you may very well never be born" thing?

Or maybe you'll just make yourself less real without altering history, a la "The men who murdered Mohammed".

Coffee's originally from Ethiopia, just across the Med.

If you're so inclined to the geology route, I'd thing a really good set of survey maps should be at the top of your list. At that point, I don't think anyone knew about the South African diamond fields, for example.

A good atlas. A pair of 1860 Army black powder revolver and enough bullets and powder for a hundred or so shots. A good size engineering and micro-agriculture library in microdot format (or maybe those funky metal disks from the www.rosettaproject.org) and a few magnifing glasses. I'd also have practiced making a moveable type press with nothing more than the tools I can fit into the remaining space. And then pack the tools.

There is a great series of books about a guy who gets time travelled to medival Poland and turns Poland into a super power with the help of his engineering knowledge.

True, but it won't come into wide use for at least a thousand years. Plus by bringing your own seeds, you get the jump on hundreds of years of breeding.

How about some fire extinguishers? Or maybe I'll just print out that page and bring it with me so that they know what to expect, since I'll be dead.

Soap. A whole suitcase full.

I'd say books on some kind of luxury crafting, like glass blowing or ceramics. Considering that there was a big luxury market in Rome, you could really clean up with your modern techniques, if you brought gold to start up a business. And because it's nothing new, just something old made better, no one would get curious, the way they would if you started selling guns or flashlights.

I'm not sure what the intention is of bringing a gun other than limited personal safety. I mean a skilled Roman archer will be able to take you out faster than you can say "reload"

An atlas will be essential. In fact you should bring several copies, have more copies made and start selling them - you'll be rich in no time. Put imperfections though in your first run or only offer subsets of geographical areas at one time otherwise some crafty guy will sell knock-offs.

Same idea with some books on advanced metallurgy. Basically the quickest best way to become rich then is the same as today: Become an arms dealer.

Lots of loose fake jewels and other small pretties, the means to make penicillin, a basic survival guide, medical manuals, a complete botanica, instruction sheets on papermaking/quill/ink/etc., seeds (thanks, earlier posters!), A solar powered taser. (Hey! I'm a woman - those people would probably want to be burning me or drowning me, or otherwise offing me right off the bat!). A few solar powered calculators to be placed into the proper hands (worth a shot, eh?). Many photographs of myself (I figure this ought to make me godlike real quick), a diagrammic book of musical instruments. A kaleidoscope or two, some binoculars, magnifying glasses, comapsses, Swiss army knives. Pack it all in salt.

Actually, you could get really, really stinkin' rich in 100 AD Rome by making high-quality paper. All they had way papyrus and vellum, no one knew how to make wood-pulp paper. Forget bringing a roll or two of TP, you'd make a mint selling the stuff to the average mater familias.

Also, dyes. There are natural petroleum seeps in Turkey. Glass-blowing was good enough to make stills then. Take along a few chemistry books and start producing aniline dyes. You'd be richer than Croesus!

I'm not sure what the intention is of bringing a gun other than limited personal safety.

Yep, limited personal defense. Most people didn't bring an archer to a knife fight, any more than cowboys slung rifles in the wild west. Personal defense needs are almost always up close and personal. I don't want someone mugging me for my carryon before I can hire some protection.

If I had the time, I'd start by educating myself (with lots o' help from smart people) so that I would know how to, for example, speak Latin, make antibiotics and anesthetics from stuff I could obtain in Rome, make lenses, mix gunpowder, predict astronomical events and earthquakes, etc. I wouldn't take a history book because I would count on changing future history mighty quickly with everything I knew. I would take a list of what the weather was like (or as much as is available to us). And I would take samples of useful things that could be reverse engineered by smart locals: a mechanical clock, a sextant, a mechanical adding machine, a model steam engine. And I would take a list of people in Rome who we figure might be useful contacts, maybe the best (and best-connected) scientists and philosophers, and I would go with some knowledge of their specialties, maybe some little bit of knowledge that would get me in good with them. I would tell them I had been lost from a ship that comes from a land far away where people can do all sorts of things, and that they'd better get cracking on replicating all this stuff if they wanted to hold their own against the people in my homeland. The plan would be to get the emperor to put a lot of people on replicating this stuff quickly, before I died. I hesitate about the gunpowder, but I would want the empire to be able to defend and spread (through colonization) all the good stuff I intended to introduce.

Hmm, I was googling around for producing steel from iron by the puddling method (which I had misrememberred as being a renaissance invention - I was probably thinking of crucible steel) and was reminded of wootz steel which apparently was a known technology from India as far back as ~2 or 300BCE (and was probably the basis for fabled weapons and armours made from "Damascus" steel - see also Neal Stephenson's Baroque Cycle). In fact, Alexander was reported to have received gifts of high quality Indian steel back in 300BCE.

Still, perhaps setting up a steel shop and selling high quality steel (as it was still relatively rare) to the Emperor/rich Senators for private armies might get one set-for-life.

Instead of helping the Romans out, perhaps bring steelmaking technology to China and convincing them that gunpowder can be used for more than fun and games?

Which civilization could provide the highest potential quality of life, in that era?

Which civilization had the hottest (by modern standards) women/boy-toys/gigalos, anyway - the Muslims (the hygene and washing thing), the Romans (the whole narcissism thing), N. Americans (the whole clean-living thing)?

Hmm, procowity - the Greeks had pretty good knowlege of steam engines and converting energy into work. Problem was that slaves were available and slave labour was the path of least resistance.

Perhaps couple Mitheral's typepress to force emancipation, then intoduce industrialism?

Good point on sextants and navigational knowledge in general. I'm under the impression that Roman ships of that era weren't worth much of a damn - I wonder what shipbuilding technology could be replicated in that era (to facilitate exploration, trade, and the movement of troops)?

Dang, I suppose four is too many, so no Little Nellie. I guess just the one will have to do....

Seriously, the permanently part is problematic. I'd persoanlly prefer a round-trip, because I'm an inveterate tourist. I'd love to accompany Hanno the Navigator, for example, but that's WAY earlier. If I could pick a time, though, I'd be hard-pressed -- there are so many interesting choices. 100 BC was the flowering of the Republic, but of course the Empire is more interesting to us in many ways and had a higher civilization. I'd also like -- given the permanent bit -- to make at least one major change, and the one I'd choose would be to go back to 150 BC or earlier, and give all my tech to Carthage instead. I just wonder how it would have turned out, ya know? And I have a longstanding admiration for Hannibal.

There's also an angle where would I rather make a nice life for myself, or would I rather change the future for the better? I can see lots of ways to do the latter with a few small, well-timed or -placed interventions. Medical knowledge, of course, or political writings. Oh, I'd love to go to Alexandria and peruse the library (if I could, I'd hope to learn what happened to it). I'd especially love to read the lost Poetics of Comedy.

And if I could go later, I'd of course want to find out more about what this guy was like. He really fascinates me, for some reason.

Everyone knows the way to riches is to invent something people throw away.

So bring a Gilette manufacturing plant along.

That'd be quite the carry on.