Can there be an equation for the likelihood of a time traveler in our time? Something akin to Fermi’s Paradox?
I don’t see how you can make the equation based on possibilities without a 0 sneaking in there.
You mean the Drake Equation, there.
And sure, you can break any unknown up into a bunch of multiplicative factors like that, but it’s never particular useful, not here, and not in the Drake Equation, because there’s bound to be at least one factor in the breakdown about which you’re just as ignorant, if not more so, as about the original quantity.
If time travel were possible, then observers ought to have been spotted at major historical events.
And if changing history is possible, this would almost certainly have been attempted, which invokes Niven’s Law. Since the temptation to change the past is irresistible, the past would be changed, over and over – the Guelphs keep the Ghibbilines from existing in the first place, etc. – until the only stable conformation is a world where time travel is never discovered.
Seems to me that were someone from the 93rd century technologically/intellectually advanced enough to have mastered time travel, remaining undetected wouldn’t tax their capabilities.
But even in the 93rd century I’m betting there will be someone human enough to fuck it up. “Foolproof” is always the first barrier mankind tears through.
Well, for all we know, maybe this did happen. Repeated time-walkers going back, re-arranging history, until the overall course of history finally converged on a stable conformation. Or maybe that convergence hasn’t fully happened yet and is still a work in progress.
Is this your or Niven’s example? A not so famous quarrel, nowadays.
Time travelers are from a sufficiently advanced future to send invisible, intangible presences. They are all around us.
Prove me wrong.
I came from the future and I’m both visible and tangible.
Prove me wrong.
EVEN if Time travel is possible, the fact we don’t see them everywhere proves nothing.
Obviously, as already stated, they might be undercover so to speak (given the nature of time travel, it might be a damn good idea to do so).
Also, even if time travel IS possible, if its not easy and common, time travelers are not going be flooding our streets (and takin er jobs!).
Opal. Maybe our time is a crappy backwater compared to all the other destinations the finite number of time travelers with discriminating tastes have to choose from.
Opal 2.0. Maybe time travel is invented 1000 years in the future. But for practical physics/engineering/economic/timey wimey reasons something like a few hundred years is as far as you can go.
Opal 3.0. Time travel is possible but not invented on Earth (because Hillary Bush is elected president in 2095 and destroys the Earth). Other planets have invented time travel, but what are the chances of them traveling in time AND visiting Earth?
The accuracy of something like the Drake equation depends on two things, really:
- whether you build in all the relevant components. We really don’t know anything about what’s necessary for time travel other than an intelligent species with technology.
- whether you know the right data to plug in. Is time travel possible at all? If it’s possible, are there limitations that prevent observers in our time? The only number we have evidence for is 0%, so we could just start there and not worry about the rest.
One of the least unfeasible methods of time travelling is by wormhole. You create a wormhole with two mouths, put one mouth in a relativistic rocket on a circular trip, and when it comes back you can travel back and forth through time via the 'holes.
But only as far back as the first creation of the wormhole time machine; you can’t ever go back any further than that. Perhaps that is why we don’t see any time travellers yet; no-one has built the first time machine. Once this is done you wouldn’t be able to move without tripping over a time traveller, but not before.
Isn’t one of the major problems with time travel the Earth’s movement through space? Even if you could travel back to last week you would find yourself suspended in empty space because the Earth has moved on since then. Unless time travel involves rewinding the whole universe so that the Earth goes back in time (and space) as well as you. But rewinding the entire universe seems like a big ask when all you want to do is send one person back a couple of days.
Pretty sure that science supports that any form of time travel is only possible to the future and not to the past.
What makes you say that?
Because we know how to travel to the future, we don’t know how to travel to the past.
This is partly meaningless and partly wrong.
As eburacum45 posted, “science” - you know, actual theoretical physicists - have determined that travel to the past via wormholes is theoretically possible, at least on paper. “We” - meaning they - don’t have the physical mechanism for that, and no physical mechanism might ever be possible, but the equations are science supported.
However, we don’t know how to travel to the future. We just do. Nobody has ever found the mechanism for this or a way to slow or suspend it. This is a fail for any meaning of “how.” Nor can we travel faster into the future than one second per second, which holds true in all reference frames. (Some reference frames may disagree on the totality of the number of seconds, but each travels to that total at the rate of one second per second.) Since we can’t go faster in any reference frame we also can’t skip ahead to any future in any reference frame, so we can’t travel into the future either. (Except by moving into a different reference frame.)
Right now, the only meaningful way to talk about time travel is the way actual scientists do. And they don’t agree with you.
“Yet” and “still” are tricky words when the topic is time travel. As Larry Niven pointed out in “The Theory and Practice of Time Travel,”
That’s true for some models of time travel, but not all. Consider a multiverse-based approach, where any time someone travels to the past, it essentially creates a new copy of the universe (or rides along with an already created copy.) So, you leave your wife and kids behind to fix the past, and you DO fix the past, but to your wife and kids, you just disappeared and never returned.
I like this model because it dodges the paradox. You go back and kill your grandfather, and on that timeline, you’re never born. No problem. But you did appear and kill your grandfather. Of course, it does it at the cost of adding whole universes. If you’re already a multiverse fan (which I’m not particularly), no big deal.
This model raises the question of what travel forward in time would mean. The simplest solution is that it’s the same as staying in the timeline but without having any effect on it. If it branches any number of times due to someone jumping back, then any number of copies of you arrive in the future (just as they would if you’d actually been there.)
Admittedly, my model would take most of the fun out of sci-fi time travel.
An even bigger problem is the energy equation. If you manage to transpose yourself in time AND space to land on the right spot, you’ll be going the wrong direction (SPLAT!) That is, you would if you still have any kinetic energy relative to the environment. If you do, you must have removed it from the past. That kinda messes up conservation equations at that time, doesn’t it? Seems to me you’re screwed either way. If nothing else, you’ve messed up conservation of matter.
I wonder how the wormhole models handle this.