You can also make an absolute commitment to publicize the convention afterwards. In that case, bring a time capsule or whatever it may be to the party, and then bury it afterwards.

Cool - how many parties can you publicize after the fact? On the other hand, "Unfortunately, we of the present (2005) don't have time travel, and so we only have one chance at observing the convention," writes Dorai. "If the time travelers don't leave us their secrets, we won't be able to go back in time and see our convention in all its glory unless it is publicized in advance."

Good point, although my head is starting to hurt.

And if I am from the future and wish to attend? "Come as you are! No dress code whatsoever. We do request that you bring some sort of proof that you do indeed come from the future, and haven't just dressed like you do. We welcome any sort of proof, but things like a cure for AIDS or cancer, a solution for global poverty, or a cold fusion reactor would be particularly convincing as well as greatly appreciated."

Hey, sports scores for the next ten years or so wouldn't be bad either.

"If you subscribe to alternative-world theory, then time travel makes sense at some level," MIT mathematician Erik D. Demaine told the NY Times. "The universe is inherently uncertain, and at various times it's essentially flipping coins to make a decision. At any point, there's the heads version of the world and the tails version of the world. We think that we actually live in one of them, and you could imagine that there's actually many versions of the universe, including one where suddenly you appear from 10 years in the future."

Or not. Planner Dorai calculates the odds of a time traveler showing up at he party between one in a million and one in a trillion. But stranger things have happened: we all exist, don't we?