Searching the Internet for evidence of time travelers

n5bb · 15 Jan 2014, 11:22 AM

This is a very interesting and simple investigation. It gives a time traveler an easy way to show their presence:
http://arxiv.org/ftp/arxiv/papers/1312/1312.7128.pdf

Bill

DrStrabismus · 16 Jan 2014, 04:01 AM

The first rule of time travel club is that you don't talk about time travel club. If time travel weren't carefully controlled there wouldn't be lottery rollovers.

n5bb · 16 Jan 2014, 12:22 PM

It's difficult to talk rationally about time travel.

Most people probably think about time travel to the past as it's portrayed in most fiction (such as movies). The traveler disappears from their "home" time, from their point of view instantaneously appears at their "vacation" time (as a new being which wasn't present before that point), and then lives with some reasonable amount of free will in that earlier timeline.
But this view of time travel has little support from physics. We currently have a poor understanding of time in science, but the current assumptions are that we exist not in space and time independently, but in a unified geometric spacetime. You can consider the spacetime distance between two events, and the speed of light is the constant which relates space and time distances. So if you are time traveling 8 minutes into the past, it's similar to traveling to our Sun as far as spacetime distance is concerned. It's hard to imagine a technique (other than a catastrophic event such as entering the event horizon of a black hole) which would allow us to travel such spacetime distances instantaneously from the traveler's point of view.
If you looked up the lottery past winners today on a website and them could break known physics and instantaneously travel to the vacation universe an hour before the lottery closed, would you have the free will to choose that known winning lottery number? And would the vacation universe lottery pick the number you had from the "future", or still meet the known laws of physics and produce a random result irrespective of your "sure bet"? If the vacation universe picks the lottery number you brought back, that implies that there is no free will in that timeline. So I don't see why the original winner doesn't still win the lottery.
But if the vacation universe has normal physics and allows what we interpret as free will and provides random results from certain tests, the time traveler will be just another agent in that universe. They might know the current state of that vacation universe from future recorded history (which is never perfectly known), but future changes to that timeline would proceed in a normal fashion, with random events and our conception of free will. So events could turn out dramatically different from what the time traveler remembers from her home universe timeline.
Now I have no idea what would happen in either vacation universe case (static history or free will normal progression of events) if the time traveler could return to their home time. Do they return to the same history at their home as when they left, or to the normal free will progression future history?
In any case, I just don't see the conventional fictional time travel story playing out.

Bill

15 Jan 2014, 11:22 AM	#1
n5bb Intergalactic Postmaster Join Date: May 2004 Location: Irving, Texas Posts: 8,929	Searching the Internet for evidence of time travelers This is a very interesting and simple investigation. It gives a time traveler an easy way to show their presence: http://arxiv.org/ftp/arxiv/papers/1312/1312.7128.pdf Bill

16 Jan 2014, 12:22 PM	#3
n5bb Intergalactic Postmaster Join Date: May 2004 Location: Irving, Texas Posts: 8,929	It's difficult to talk rationally about time travel. Most people probably think about time travel to the past as it's portrayed in most fiction (such as movies). The traveler disappears from their "home" time, from their point of view instantaneously appears at their "vacation" time (as a new being which wasn't present before that point), and then lives with some reasonable amount of free will in that earlier timeline. But this view of time travel has little support from physics. We currently have a poor understanding of time in science, but the current assumptions are that we exist not in space and time independently, but in a unified geometric spacetime. You can consider the spacetime distance between two events, and the speed of light is the constant which relates space and time distances. So if you are time traveling 8 minutes into the past, it's similar to traveling to our Sun as far as spacetime distance is concerned. It's hard to imagine a technique (other than a catastrophic event such as entering the event horizon of a black hole) which would allow us to travel such spacetime distances *instantaneously from the traveler's point of view. If you looked up the lottery past winners today on a website and them could break known physics and instantaneously travel to the vacation universe an hour before the lottery closed, would you have the free will to choose that known winning lottery number? And would the vacation universe lottery pick the number you had from the "future", or still meet the known laws of physics and produce a random result irrespective of your "sure bet"? If the vacation universe picks the lottery number you brought back, that implies that there is no free will in that timeline. So I don't see why the original* winner doesn't still win the lottery. But if the vacation universe has normal physics and allows what we interpret as free will and provides random results from certain tests, the time traveler will be just another agent in that universe. They might know the current state of that vacation universe from future recorded history (which is never perfectly known), but future changes to that timeline would proceed in a normal fashion, with random events and our conception of free will. So events could turn out dramatically different from what the time traveler remembers from her home universe timeline. Now I have no idea what would happen in either vacation universe case (static history or free will normal progression of events) if the time traveler could return to their home time. Do they return to the same history at their home as when they left, or to the normal free will progression future history? In any case, I just don't see the conventional fictional time travel story playing out. Bill

16 Jan 2014, 04:01 AM	#2
DrStrabismus The "e" in e-mail Join Date: May 2002 Posts: 2,804	The first rule of time travel club is that you don't talk about time travel club. If time travel weren't carefully controlled there wouldn't be lottery rollovers.