Imagine that you’re hyper-genius friend QUERCUS SHOSANNA reveals to you that she has invented a time machine. Quercus’s technique is subject to the Novikov self-consistency principle, (Novikov self-consistency principle - Wikipedia ) meaning that travel in this fashion can never effect a change in history. Trying to avert anything known to have occurred — weather as trivial as a failed geometry test or as monumental as 9/11 — will always fail. Both the mathematics of Quercus’s theory and experimental evidence (she has already made more than a hundred time travel trips) bear this out. She even takes you back several times so that you can see this for yourself.
Quercus’s time machine does not allow for travel into the future of the traveler, only the past. Assuming a traveler chooses to return from their trip (that is neither required nor assured), they always arrive approximately 427 milliseconds after leaving. Additionally, because of the way the machine works, travelers are gravitationalally locked to the nearest planetary body when using it. In other words, they don’t have to worry about accounting for the Earth’s movement through space when using the machine, as they are unable to leave the Earth in the first place. Again, both the mathematics of Quercus’s theory and repeated experimental evidence bear all this out.
Quercus has shared this knowledge and experience with you because she values your opinion. She is considering whether to share this knowledge with the world. How do you advise her on this issue?
Is there any reason not to? If you can’t change anything, it’s more like a VR time viewer than a time machine. Maybe do a little more beta testing with a variety of experts first, but then roll it out.
Here’s a (possibly opposing?) view: People here-and-now are making decisions all the time, and these decisions are based in part on our knowledge of the past. But our knowledge of the past is incomplete and not always accurate. (Just think of all the secrets our politicians keep and the lies they tell. If the truth were known, other people would be making different decisions.)
So if someone could go into the past and discover stuff for themselves, and could then bring this knowledge back with them (which they might or might not share with others), then they (and perhaps others) will make different decisions than they would have.
I don’t know, and won’t speculate, whether this is a good idea. But one could ask if it would be a bad thing if this time machine were only available to some people and not equally available to everyone. Can it be good if some people can make decisions based on “insider knowledge” that is not available to everyone?
Of course, that happens all the time already. The Q.S. time mochine will just make it even more so.
Novikov’s self-consistency principle does not mean that a time traveler can’t change things, any more than it means that we ordinary non-time-travelling beings can’t change things. It just means that when you change things, they stay changed. Effects can still be caused by a time traveler; it’s just that the traveler, when they step into their machine, will already remember those effects (assuming they’re something the traveler knows of).
And you tried to get around some of the problems by preventing “travel into the future”, except that you removed the parts that are no problem at all, and left in the parts that cause the big problems. Travel into the future is easy, and we already know how to do it.
If the world had access to a time machine of this type, society would quickly crumble in a sea of anarchy and criminality.
Imagine all those with evil intent who are kept in check by the fear of consequences for their actions. With a way-back machine, consequences could be easily avoided.
Want to murder someone? Go for it. If the cops start closing in on you, go back in time and start with a clean slate. Do it again if you want. Keep murdering until you get away with it. Not only does the victim in your current timeline get murdered, but all the alternate timeline victims get murdered, too. That’s a lot of murdering for one person to endure.
Personally, I would consider it excessively inconvenient to be murdered more than once.
This scenario assumes Chrono’s interpretation. In the OP version, you’d just have to commit the crime (once or multiple times) and go back further in time each time so that the consequences never catch up to you.
I’m happy to yield to your superior understanding of the physics. But let’s ignore that part. Simply granted that Quercus’s machine allows for backwards travel only, not alteration of history, is there any reason to oppose the dissemination of the technique?
As for the elimination of future travel, I did THAT simply because I’m not interested in it.
Why would your scenario of criminals escaping prosecution via time travel be any worse than their doing so by traveling to countries lacking extradition with the jurisdiction where their crimes occurred?
I am always happy to help Quercus with the practical and ethical deficits which commonly accompany genius. In order to answer her truthfully I must know what she knows about this tech and the theory behind it. Once this is done, the only question is whether to strangle Quercus or abandon her in the distant past using her own machine. Time travel of this sort brings only knowledge. Knowledge contributes to insight and thus power. Should Quercus share this tech? To even pose this query is madness, for to do so is to share power. Infantile.
Novikov self-consistency specifically rules out alternate timelines. If you go back in time and change something, that change has always been there and is part of the future timeline, even if you didn’t know about it when you set off.
For instance you could go back in time, set up a few high-interest savings plans or shares portfolios, and come back to the present to collect the money and the interest. Those bank accounts have always been there, it’s just that you need not have known about them before you set off. The invention of Novikov-consistent time travel could cause financial havoc in a fairly short time, by concentrating wealth into the hands of time-travellers.
Not to fight the hypothetical . . . but what do you mean by “not alteration of history”?
To me, that seems to mean, “no change in anything, no matter how small” (which you imply in your OP).
While, how can one be in a place without effecting it? Displacing molecules that weren’t displaced before.
A problem with popular “history is fixed, but we’re going to time travel anyway” stories is that they only focus on a few specific outcomes as being fixed. Things that happen to be in the history books. The problem is that “history” is literally everything that happened, not just the things that have been recorded or that we have direct evidence of in the present. There is no way for a person to be in a place they weren’t before, and have zero impact on the history of that place.
And, all that is to say, I’m not sure what time travel looks like in this context. If the traveler can’t interact in any way with any matter or substance of the past (which doesn’t sound like time travel at all), then what benefit or use is this tech to begin with? How do you even know you’ve time traveled, if you can’t prevent photons from reaching the blade of grass behind you by intercepting them with your eyes?
Somewhere I read a short story on something similar - it was a view-only time-machine, so no problems with changing the past. Now that I think about it, I’ve read two stories like that, one may have been Dangerous Visions.
It was ruthlessly controller/suppressed by the government because it was the ultimate surveillance app (in one story - the other imagined what society would be like if it was generally available) - the past is the instance that happened just before now, so given the desire to look, you could basically use it to watch anything real-time.
At any rate, it would completely upend current view of privacy - I could pop into the Oval Office and listen to the president at will. I think general access to such devices would lead to a more open society. Not sure if that would be a good thing or not - certainly no way to know, since we can’t use it to future travel.
I think most people are misunderstanding the mechanics of the Novikov consistency principle. Your time travel actions would already be part of history, even before you do it. It’s not that you can’t change anything, it’s that your changes have already had the effects on your current timeline.
That’s right; that is what consistency means in this context. It doesn’t mean that you can’t go back in time and do things; it just means that the things you do are already part of history. So you could go back and open some high interest accounts, but they would already be part of history before you set off.
We’ve discussed the view-only time machine in a recent thread, about whether it would kill religion. My own opinion about this was that it would not, but it might kill certain religions that are based on lies. It could also kill certain political movements that are based on lies too.
Don’t forget that we can travel into the future, using current technology, just by waiting for things to happen in the normal way.
I don’t know for sure my bitter enemy George is alive, but don’t have any reason to believe him dead. Can I go back and kill George? A world with a dead George is not incompatible with the way I understand the world to be at the moment.
In order to really understand the hypothetical, we would need to know how the Novikov self-consistency principle is enforced. Either there are going to have to be severe restrictions on the application of the time machine, or else there are going to be severe restrictions on free will.
So what happens if a person sets the time machine to a place where he historically wasn’t? Does the machine simply fail? In that case I would imagine that there would be a lot more failures than there are successes. Also if you do succeed in going back but try to act ahistorically what happens.
The easiest solution to this is a look but don’t touch style time machine. The other way would be a more useless version in which you could send particles back in time but had no control over where they ended up and what they did. Sort of like the reason you can’t use quantum entanglement to send information. The third possibility would be to totally eliminate free will. While it may already be the case that free will doesn’t exist and what we think of as free will is an illusion, the existence of such a time machine would instantly dispel that illusion as the first thing any experimenter would try would be to go back 5 minutes and say hello to ones self.