While growing up, I’ve often been captivated by movies and books on time travel. Things pertaining to time travel, that I once truly thought were possible have become absolutely absurd. Even through physicists’ explanation of machines that one day can manipulate space-time travel or wormholes has never sound so scifi to me before.
How can one, through speculation or all serious theories believe for one second that it is at all possible. Sure, more recently than ever, we would love to believe anything is possible. But I honestly think this is one exception to the belief.
To say that time travel is even remotely possible, in my opinion is just plain ludicrous.
Even if time travel were possible, at what point was the starting point? Is now really now or our past.? If time is no longer a constant (single) plane with in this universe, then time would have to be readily reoccurring at all times like a reel of film.
This explanation of a Multi-verse or Parallel Universe, where all different possibilities make up one reality and the bending of space and time to arrive at one of those different scenarios makes my head really, really hurt.
If this were even one of the more possibilities…how can that possibly be called time travel or even related to it?
If this far fetched theory is even slightly correct…How in the world would it affect us in this universe should some one alter or disrupt time? Theoretically…who ever time traveled to one of these parallel universes has only changed reality as he/she knows/knew it. Those of us in the current universe would go unaffected if events have been altered…right?
I dunno, the cause/affect/and even possibilities are too out of this world to fathom it.
Well, events would have already been altered. If time travel is possible, and there are countless parallel universes, then there would be universes in which time travelers from other universes inserted themselves into the timeline. If we lived in such a timeline, that time traveler’s appearance would already be part of our history.
Good point, haven’t thought of it in that perspective. But…if this were the case. To what purpose would time travel to any of the parallel universes serve? If these parallel universes exist, wouldn’t the individual traveled to one of these, only gain for self? People have speculated that time travel could possible help and change the world for the good or worse or maybe even affect as little as a group or one persons life. How can this be if parallel universes exist? In fact, why change anything? Apparently since there is supposed parallel universes, all one would have to do is travel to a specified event or path he/she is seeking since it already exists through multiple streams of time. Hell,…am I even me? I apparently may already be dead in many of those universes.
I think it was Kip Thorne, an eminent physicist, who a decade or so ago decided he was fed up being asked about time travel and set about to prove it was not possible. He was surprised to find that there was nothing in physics, as it is (or was then) understood, that prohibited it.
That said for a lot of sticky and paradoxical reasons no one is really comfortable with thinking it is really possible and kind of assume there is something that prevents it that we just have not figured out yet.
Nevertheless there are some reasonable proposals out there for how it might be achieved (e.g. tug one end of a wormhole around at close to light speed and travel through the wormhole). However, all those ideas rest on as yet untestable and/or unproven things (no one has seen a wormhole for instance) not to mention practical considerations (tugging around one end of a wormhole at near light speed can’t be easy and traveling through one may not be possible) so it remains in the realm of science fiction.
Traveling to a parallel universe might seem like time travel in as much as you end up in an alternate reality but it is not time travel per se I think. You’d just be moving yourself to a universe where they were not as far along the timeline. It should be noted the Many Universes idea of quantum mechanics, while not debunked, is another of those ideas just too astounding for most people to really accept as true. Even if it was true how you would move between them is perhaps even more problematical than time travel. If you could though it would be amazingly cool. All of us (and I do mean all of us) could travel to a universe where we were Emperor of the Earth…or whatever floats your boat. Pick a reality you like best and go live there.
Quite an existential quandary, isn’t it? If there are billions of “you” out there, many of whom will be committing evil acts, are you a good person or a bad person? If you went to a world that seemed almost exactly like your own, but the people there weren’t technically “your” friends, family, country, planet, etc., is there any reason to help them?
Here’s the thing: to my knowledge, we really know almost nothing about the nature of time, and barely any more about structures like wormholes and other things that dwell in conditions far outside of anything in our experiments. In short, it might be possible, and we simply can’t do anything to prove or disprove it for the foreseeable future. Any actual physicist is urged to show how everything I’ve said is wrong.
The fact that we haven’t been inundated with future-tourists suggests to me that if time travel is invented, it’s so far in the future that whatever species accomplishes it has no interest in us homo sapiens, meaning we’ve either been replaced or have evolved into something entirely different, which I guess is the same thing anyway. In either case, it won’t be in our grasp anytime soon.
I’m assuming your talking about a travel faster than the speed of light scenario, that doesn’t involve a multi-verse. Who’s to say that hasn’t happened already (as spittletoad similarly stated) and why would it be so far into the future that we have already evolved? In that regards it may have been Bigfoot a sign that we reverted back to an ape like state. If so, then maybe there is proof that we already have a time traveler among our existence!lol
No, really. If time travel were at all possible, then I believe nature or our universe would have some sort of evidence that it could reveal it to be possible at all.
The splitting of atoms occur naturally. Therefore, we are able to wield and modify it to benefit us. Fire occurs naturally, therefore we can produce a spark and too carry a flame or even intensify it to degrees hotter than the sun. Where, at any moment in our reality does even the slightest manipulation of time occur “naturally” in any distant relation? The fact that time moves forward can’t possibly justify the thought that it can be moved backwards? Could it?
Another possibility is that if time travel is possible, it’s only possible back to the creation of the wormhole or whatever that allows it. Or it’s possible but has a price that future people are unwilling to pay, like being unable to return ( such as in a multiple-futures scenario, where there are billions of billions of possible futures - which did you come from ? ).
Or there’s an idea Larry Niven came up with; if you can travel back in time and change the past, and that affects the future, the end result will be a timeline where no one ever invents time travel. Because if time travel IS invented, the past will be changed, and changed, and changed; the only stable timeline in that scenario would be one where time travel is never invented. Niven’s Law something-or-other.
I’d like to think it was possible. Unfortunatelly Der Trihs is correct in that all of the currently theorised potential time machines are only able to take you back to the time they were activated.
For example (and I will be back with a cite later) the most likely theoretical time machine involves using materials with high refractive indexes to slow light down so it is possible within the machine to travel back in time. However, you can only travel back in time to the time it was activated.
At the moment time travel seems on the face of it, theoretically possible, but it causes lots of problems not least of which are the possible paradoxes. For this reason some physicists – such as Stephen Hawking with his Chronology Protection Conjecture – have hypothesized that time travel must be impossible.
I personally don’t think paradoxes rule out time-travel, because there may be ways to sidestep the paradoxes. e.g. parallel universes, or maybe just an explanation that we haven’t though of yet.
I would say however, that one ‘resolution’ that many people give – e.g. that in the “grandfather paradox”, you could travel in time but you’d be unable to kill your grandfather – is particularly implausible to me, since it would require some sort of context-sensitive physics.
My final point is to the OP: Your assertion that time travel is ludicrous seems entirely based on your own intuitions. But intuition is not a good guide for many aspects of physics. The idea that spacetime is curved/warped by matter seems intuitively absurd. And yet the evidence strongly supports this theory.
That’s confusing… If this device was activated, you would have never really left the time or physical spot with which your in? Basically still left with a theory? What about it’s ability to move forward? Is it limited as well or is that an impossibility in that theory? That reminds me of that kid in school who claims to be faster than the eye can see,…“Wanna see?..See…I told you I was fast…you shouldn’t have blinked!”
I agree with your statement above. My Assumptions of certainty with in quantum physics is entirely based upon my own intuition with no evidence to support my belief. There is a modest amount of evidence to support claims of time manipulation. Most of these theories support “forward” moving time whether in a crawl like state or where time has jumped forward. Does this actually make science fiction time travel a reality? Would it be true that through these variable possibilities, one could travel backwards?
Feynman discussed auditing a philosophy class one day, and in an effort to understand a concept they were discussing (“essential objects”) he asked: “Is the inside of a brick an essential object?” His goal was to discover whether “essential objects” included theoretical constructs; he was going to point out that no one has ever seen the inside of a brick, because the moment you break the brick, it’s half a brick with a new outside. The idea that a brick has an inside is basically a model, a useful concept to understand and predict the nature and behavior of bricks.
All of science, all of our understanding of the universe is based on the idea of a model. I’m sure the first “law of gravity” said something like, “Objects fall at such-and-so rate of speed.” That was a useful model, because it accurately described the behavior of objects. As time went on, we refined it to note that air resistance could change the speed of falling objects. Still later we refined it again because it turns out that objects fall at different speeds on the moon, and relative to a space capsule in orbit they don’t fall at all. The best model, we declared, is that any two objects are pulled towards each other with a force proportional to the product of their masses divided by the square of the distance between them.
I say all this only to say that it’s possible, at some point in the future, we may discover a circumstance in which F=GM[sub]1[/sub]M[sub]2[/sub]/r[sup]2[/sup] is no longer the best model, and if we find ourselves thus, we’ll revise the model to deal with the new circumstances. That’s the essence of the scientific method.
Now, time travel.
Time travel undercuts a basic assumption that allows us to manage the scientific method: the law of cause and effect. I’m not going to say that time travel backwards is utterly impossible – but it’s nearly so, because if it isn’t, then every single thing we think we understand about the way the universe works will have to be revised. The change of the model, in other words, would be vast and its implications dramatic. We have neither the language nor the analytical tools to approach it.
There’s a time travel problem I’ve never seen addressed. It’s kind of an engineering problem. Suppose travel backwards in time is just like travel forwards in time, but backwards. (I.e., no teleportation through time, but rather, smooth continuous travel backwards along the time dimension.) Then when a body begins to travel backward in time, it seems like it should sort of “collide” with its heretofore forward-moving self. I don’t know exactly what the result of something like this would be.
-FrL-
ETA: This is the only real problem I had with the mechanics of time travel in the movie Primer, and I shouldn’t call it a “real” problem since in almost any time travel story I’m going to have to suspend some kind of disbelief.
It seems to me that for time travel to be possible, the past must ‘exist’. If it exists, then our perspective of the ‘present’ is an illusion because the people/things in our past would think the same way.
So, does the past actually physically ‘exist’? Is the battle of Tarawa actually being fought ‘right now’ somewhere?
Serious question…Let’s assume the past does not exist as an axiom and see if this results in a contradiction. I am not a physicist…but is there something in physics that would imply that the past not existing results in an absurdity?
Mankind hasn’t been able to demonstrate itself as being sufficiently bright enough to pay attention to pretty much every time travel story ever written for people to invent the thing and not use it. Once invented, the ability should be available from that point forward, so, unless this particular time (aka our recorded history) is considered so fantastically dull that nobody wants to visit it, we should be up to our armpits in time travelers.
There’s a time travel problem I’ve never seen addressed. It’s kind of an engineering problem. Suppose travel backwards in time is just like travel forwards in time, but backwards. (I.e., no teleportation through time, but rather, smooth continuous travel backwards along the time dimension.) Then when a body begins to travel backward in time, it seems like it should sort of “collide” with its heretofore forward-moving self. I don’t know exactly what the result of something like this would be.
This to me is why time travel through this scenario is unlikely. That would mean your current self, as traveling back through time would have to dematerialize to a non existent state. This would also be true to your current mind, cells, and the device that provided backwards time travel. What force could shield the recession of what time has contributed to self (biologically)and the device in which was used to travel in?
