If I go back to 1970 with key dates, I could simply set someone up with power of attorney to make explicit stock buys/sells on certain dates.
You can’t go back to 1970. Sixty year minimum, remember? Admittedly, you could try what you’re suggesting in 1940, but it involves being very trusting. Your attorney-in-fact is not going to hear from you for a long time, after all.
Two things here, amigo. One is that I expect time-travel’s no-changing history rule isn’t like footballs’s…um…okay, I can’t actually name any football rules. It’s not a condition set up and enforced by the will of the officials and the self-discipline of the players. It is, rather, like the laws of thermodynamics. It’s a consequence of the way the universe works. It might be better stated that no change in history will be perceptible or meaningful to the persons who send the traveller to the past and return him to the future.
Let’s consider Hitler. Let’s even grant that World War II and the Holocaust would never have happened without him, and that let’s say that Mossad Officer Ziva David stumbled across this tech and decided to off the painter. So she pops back in time, intending to kill him. Now, Ziva’s a badass, so it’s surely possible that she’ll figure out a way that might work. But, nonetheless, HER history prevents it. If she kills Adolf and averts the Big One, she also removes all her own motivation for coming back in time in the first place. Maybe this creates a alternate universe in which WWII never happened; maybe this means the time travel machine was subtly miscalibrated, and instead of being the past of of world (Earth Analog 1938740943-pds), she went to the past of Earth Analog 1938740943-qbs. In either case, the people she left behind in our time won’t perceive any difference.
Still not buying it. If nothing I do can actually change history, I don’t see how I can interact with the past at all. Say I’m innocently roaming around Egypt in 1796, and accidentally destroy the Rosetta Stone. Crushed it to powder when I dropped my backpack on it or whatever. That rock is now dust, has been dust since 1796 and won’t be there for Lieutenant Pierre-François Bouchard to [del]surrender to it[/del] discover it in 1799.
Or say I happen to play intramural badminton against Neil Armstrong at Purdue in 1947. He falls while trying to reach my famous drop shot, and puts his own eye out when he lands on the shuttlecock. He never goes on to become a fighter pilot or an astronaut, because he couldn’t pass a flight physical. Somebody else takes that “One small step…”
Which means that you won’t be able to drop your backpack on the Rosetta Stone.
I didn’t say that time travellers cannot CHOOSE to change history. I said that they simply cannot. Likewise, your Neil Armstrong example is prevented by destiny. Or else you the time travel device was miscalibrated and you’re in an alternate past. In that case, you may be able to do things that would seem to cause history to unfold in a different way than you recall; but you’ll also lack the information to do so in any way that’s meaningful to you.
I daresay you’re fighting this hypothetical because you so strongly believe in free will. (Which I do as well, but but for this exercise.)
Probably. Such is my nature. But now I wanna go drop my backpack and watch it hover over the Rosetta Stone. 
It says here that a single 1856-O double eaglewas recently auctioned for $1.8 million. What’s to prevent me from spending 1,200 2010 dollars for an ounce of gold bullion, then going back to 1856 New Orleans, going to the mint, trading my bullion for coins and coming back with them.
And why stop at bullion? What’s stopping me from traveling back to Springfield, Illinois in 1860, picking up a copy of the local paper on the day Lincoln was elected President, strolling over to Abe’s law office, getting him to autograph the newspaper, and taking it to Sotheby’s when I return to 2010.
So, profit or not?
If it would work, I’d not have a problem with it. I’m not sure it would work, though. Are you planning on pretending that the autograph has not travelled through time? Because, presumably, it won’t seem to be 150 years old, and thus will fail authentication.
As to the first matter, I think it would be worth the effort would depend on how much the time travel trip cost. The Russians charge, what $25 million for a ride. I can’t imagine the time travel trip being less.
Oh, it’ll work. I simply have to work out my family tree back to the Civil War, and go back and make a moderately rich man of one of my great-great grandfathers. A few intstructions about making regular transfers to my secret swiss account, as well as where to hide the 1936 Packard 120 Convertible and viola! Bob’s my uncle!
Now all I need is the time machine.
Again, I don’t have a problem with it; if you’re going to the Real Past, then whatever you’re planning is destined anyway. I just am less sanguine about the plan working than you are. 150 years is a long time. If you’re rich enough to pay for the time travel trip in the first place, I can’t see bothering with the scheme.
I thought The Complete Time Traveler: A Tourist’s Guide to the Fourth Dimension had a pretty good setup, although it’s been years since I’ve read it.
It’s mentioned that one of the first things that the time travel commission did upon formation was travel back five years to the past, so they’d have enough time to design the rules and regulations for time travel.
Of course it will work. The paper and ink were manufactured in 1860. It doesn’t matter whether I lock them in a safe or time travel them back with me. In 2010 they’ll be 150 years old and easily go through the authentication process.
Another question. Maybe I can’t change history myself, but suppose I go back to 1940 and meet my father as a young man. I happen to mention that he’ll be married in the next couple of years, then a world war will break out and he’ll be drafted, leaving a pregnant wife behind.
All things come to pass, except this time my father decides to use condoms every time he has sex. When 1942 arrives, he is indeed drafted but his wife isn’t pregnant. Poof, my sister is never born, nor is my other sister conceived while he’s home on leave. Of course, I wasn’t conceived until long after the War was over, so there’s no paradox in *my *being born. But what about my sisters?
The reason you can’t pop out Armstrong’s eye is that you didn’t. If you go back in time and play badminton with him, you haven’t changed the past, because you had already played badminton with him before you ever left. Every action you take in the past already happened. There’s no cosmic censorship principle, no time patrol, no clock roaches. It’s just that there’s no way to change the past, because it already happened. Of course, the obvious corollary of this sort of time travel principle is that you can’t change the future either, because the future has already happened too. No free will, complete predestination.
Expect a lot of people to start jumping out of tall buildings when they find out their lives are completely meaningless. Of course, they were predestined to do that, so there’s nothing you could have done to stop them anyway.
Of course, this is only one theory of time travel. There are others…
Presumably, the time travel process does not subject the ink to whatever effects of aging ink usually suffers, in the same way as you yourself will not return to 2010 a decrepit old man (or arrive in 1860 a, uh, mere twinkle in your male ancestors’ eyes).
I don’t know much about the authenticiation of old documents, but I should think that the fact that the dox in question didn’t experience the intervening 150 years, any more than you did, would mean they’d fail the test. And obviously the time traveller doesn’t experience the 150 years, as he doesn’t come back dead.
So you have to lock them in a safe or whatnot. That might work; but you just can’t be absolutely certain of it, because you’re not present in the intervening time.
Honestly, I can’t imagine the Abe Lincoln signature being worth the the expense of the trip.
One theory I’ve heard is that time travel is inherently unstable. Any time travel into the past will have some effect, great or small. So history is constantly changing as time travelers keep making all these changes. And at some point, either deliberately or accidentally, somebody will change history in such a way that time travel is never invented. And at that point, all time travel stops and there are no futher changes in history. So even if there are a billion different possible timelines with time travel and only one possible timeline without time travel, we always end up in the one with no time travel.
I disagree. It would be easy to manufacture paper and ink in 2010 using methods that were used back in 1860. So the manufacturing methods alone aren’t going to prove the age of the paper and ink.
It sounds like for all practical purposes you’re a disembodied being, ie you’re there but cant do anything meaningful. So the main attraction is observation rather than what you can do.
If you can interact in ‘insignificant’ ways, you could go back and have nookie with famous figures or the like, but really, would you want to given past hygiene practises??
If its incredibly expensive theres no obvious profit motive from Abes signature or the like, it would have to be bigger than that. You could get Picasso to do another work I guess and the time travel people could certify it and the market would decide if it was worth more or less than genuine ‘old’ works. Presumably there would be a limit, where Picasso has to get on with his known work and you risk dropping dead on the way to see him so as not to interfere. Sort of time travelling roulette?
The main thing for me would be solving mysteries - greek fire, Jesus, what happened to the USA Vikings etc. Are you allowed to nick stuff thats currently unfound anyhow, eg gold on the Titanic or whatever?
Otara
It’s not exactly that you can only interact in insignificant ways. It’s that the significant ways you interacted have already happened. So you certainly can go back in time and kill Xerxes Zizzik, who would have become ruler of Kazakhstan in 1922 and instigated the Central Asian Genocide which would have killed 100 million people. In fact, someone already has, maybe it was you. That you’ve never heard of Xerxes Zizzik doesn’t mean his death was insignificant, only that it already happened.
But you’re right that since you can’t change what has already happened (and therefore can’t change what’s going to happen since it’s already happened in the future), then there are certain constraints on what time travel can be used for. Gathering information is one. Certainly you can bring back artifacts from the past, or bury things in caches to be recovered in the “present”. But you can’t go back in time and save JFK, and the proof that you can’t save him is that nobody saved him, because he died. I don’t know why your plan to save JFK will fail, all I know is that it must fail, because it has failed.
If that is true, then there’s no reason to not treat time-travelling like a holodeck, and just go back in time to indulge any twisted fantasy one might have. Why not nuke Manhattan? Won’t really change anything in history as we know it…
Abe Lincoln signatures are valuable because they are rare compared to the number of people who want one. That near-proof Liberty coin is valuable for the same reason–it is very rare. If time travel make Licoln signatures and proof gold coins common then the price will fall.
One regulation not mentioned is that everyone who goes hunting in the Jurassic has to be able to handle a Continental .600 rifle.