Hello friends :wavey: The Maniac Insomniac has a question for those who know more about this subject than I do. In mathematical models more complex for me to even begin to understand, it is theoretically possible to travel back in time. For the moment, please ignore the logistics of making this happen and the numerous philosophical questions about meeting your past self and whatnot. In my feeble, but curious, little mind, it could only be possible to travel backwards in time, while actually arriving in a past physical state of the universe, if there happened to exist within the universe a "memory" of sorts which "stored" a "record" of all previous states within which one could return. This would open up the question of in what manner is such information stored. If not, then we would have two possible other outcomes as far as I understand it so far, one of them rather unsettling. The unsettling possibility is that the universe, including life, is deterministic. Time travel would be, essentially, turning back the gears or plugging in previously used values for variables into the same equation. The second would be that the time travel only happens technically, but that whatever occurs in that situation is one that we do not have the ability to predict, perceive nor explain. Maybe that which is subjected to time travel is sent to some in-between layer of spacetime whose dimensions are imperceptible to us. Maybe the universe crashes like a faulty piece of software with a major glitch in the code. Maybe I just need to get to bed :|
Like many other things in life, it can be more complicated than you first imagine: A-series and B-series - Wikipedia, the free encyclopedia
This has to do with how we understand event sequencing, rather than time as an entity in an of itself. I'm looking for an answer in psysics, not philosophy. Although I do love me some good old philosophy.
We all travel forward in time. Relativity allows us to look ahead to traveling faster than others forward in time, once the propulsion technology is available. The physics are against backwards travel.
Just think, about 25 or 30 years ago if you saw a person walking down the street or going into an elevator talking into a blue-tooth ear piece, you would had him shot !! imagine what we can come back in time and do 30 years from now.
Conversely, God created time, which means that the rules of physics (as we understand it) may be circumvented by the One who created everything, if and when He so chooses.
Since we have only experienced time, it's difficult for us to conceive of an absence of time. God created time, which means time has limited parameters. All created things have parameters. God has no parameters, which means He is outside of time.
The notion of a present-day, free-styling God is an interesting one. If true, there are no physical laws, just permissions from the Big Guy. Things could go sideways at any moment; there are no rules and the universe is predictable only as He lets it be. Got any examples of this happening in our era?
Getting back on-topic for a moment, not only is backwards time-travel not indicated by the physics, it would seem that it has not ever been discovered--even in our future--for if it will be true in the future, we'd have visitors from there. Or perhaps they are here and are managing to stay hidden.
Or perhaps it's possible, but it requires two functioning apertures, and the first one hasn't been invented yet.
"Déjà vu all over again." (Yogi Berra). :smile: Yes - we have "been here" before. There was a thread discussing this classic science fiction story involving backward time travel: Timescape - Wikipedia, the free encyclopedia Thread is here: http://www.degreeinfo.com/off-topic-discussions/26317-retrocausality-aka-time-travel.html BTW - I have no idea how the Stanford experiment (described by Dr. Bear) at retro-time travel turned out. Maybe I should go back to 2007 for a look? :smile: Johann
I think the question of most import also directly relates to the question of this thread. What exactly happens to something that travels backward through time? We can imagine that it shows up in some previous point along our same timeline as if conjured, which is pretty much what Rich talks about in his post above. On the other hand, since it is not the universe itself, but only a limited amount of matter that is being subject to time travel, we can phrase that question in a different way: what happens to something whose time has been reversed? You see, since time is relative (which opens the possibility of this discussion to begin with) it could very well be that nothing in the universe is affected by the time-jumping mechanism other than that which is submitted to it. In that case, what happens to it? I imagine that its entropy should decrease... but how would that actually affect the time traveling thing in practice? :crazy: With any luck, Stephen Hawking himself will chance upon this thread, point out all of my errors of fact and reasoning, and answer all of my questions.