Tangled Invitation

Just read a Wired article on the potential for forward-only time travel using quantum entanglement. Cool article, lays it out cleanly even for those that don't know a ton about quantum mechanics. Based on what I know of this field, and what I know about quantum entanglement, I totally buy this argument - I think it's completely reasonable, and almost obvious to those that happen to look in that direction.

Here's the quick idea - two particles (typically photons) can be created so that in some ways they act like one, until they are measured in a particular way, at which point one takes the 'positive' value, and one takes the 'negative' value. If they aren't both measured the same way, then they aren't guaranteed to be mirror images of one another, and so the act of measuring an entangled photon in Guam is actually impacting (instantly) the value of measuring its entangled sibling in Bermuda. This behavior is pretty well established in the scientific community, lots of experiments that confirm this behavior, lots of theoretical support for this behavior, etc. The thing that all of these experiments have in common, however, is that they separate the two photons by a certain amount of space. What the scientists in this article demonstrated was what happens if the particles are separated in time, or rather that it was actually possible to create a situation where two entangled particles were separated by time, not space. What you then end up with in that scenario is the ability to teleport quantum information from one end of that linkage to the other. (caveat - I'm only part of the way through the arxiv article)

So that got me to thinking (we are in Completely Unsupported Bullshit Land, btw) - if you can entangle the past to the future, it seems like you could reverse that effect: measure the future particle "first", which would cause the entanglement to collapse "before" the "older" measurement, which could then allow you to teleport a quantum state backwards in time.

There would be a catch - the entanglement has to be generated from the "older" point in time, and at that point you don't know what information might be sent back, so you'd have to generate the "carrier states", read them and reconstruct a quantum state on the *assumption* that one was teleported back from whatever the future target time was, and see what you get. Sort of like sending a self-addressed, stamped envelope into the future and seeing what was sent back.

Assuming you manage to engineer all of the kinks out of that process, including the reminder to send something back in time, 15 minutes from now (instead of grabbing that coffee you needed), then you've just created a way to directly evaluate the 'multiverse' theory of time evolution.

some scientists believe that every possibility of every decision actually takes place, and results in multiple universes in which each of those possibilities is played out. some believe that the universe is neatly buttoned up, and you are simply unable to do something that would violate the self-consistency of the decisions that have and will be made. This is hard to envision until you start thinking about time travel. Maybe just watching "Back To The Future" (parts 1-3) would give plenty of explanation: if you go backwards in time and convince your mother to be a nun, would you suddenly disappear, would you continue to exist as this alternate story played itself through without your birth, or would history somehow "heal" itself by finding some other means of causing your birth?

With this 'backwards in time' setup, you could measure that directly -when you send an invitation into the future, then the reception of information back from the future could alter that future. if the future disappears / changes sort of 'instantaneously' based on changes in the past, then that should tend to disrupt the ability to receive a coherent message back from that future. For example, I receive a string of numbers from the future that looks like a lottery number, I'm going to suddenly stop focusing on science and get my ass to the nearest gas station to try that sucker out. If it was legitimate, then I might be to hungover the next day to go to the lab and send that number back to myself. Heck, I might have taken a sudden trip to Bermuda. If the future is changing based on my having won the lottery, then it seems like it would be difficult to receive (at the very least) more information after that lottery number, since that was the information that would *cause* the future to change drastically, but possibly even getting *close* to the completion of that number would cause oscillation among the possible futures, some of which sent the message back to me, some of which did not. Sort of like talking to a multiple personality individual whose personality switches were triggered by the word "the". Pretty much any conversation with this person cause multiple switches, and really hamper their ability to participate in the conversation.

Bottom line, is that if we ever demonstrate this effect in reality, and if my conjecture regarding the ability to send information backwards is accurate, then the ability to receive a clean signal from the future would significantly weaken the multiverse theory, while the inability to receive a clean signal would support the multiverse theory.