Travelling forward in time is no big deal. We all do it all the time at a speed of one second per second: sometimes awake, sometimes asleep! Every second of every minute of every hour we go from present to future.
Travelling backward in time, however, is thought to be impossible. There's the so-called "Grandfather Paradox": If you could travel backward in time, you could murder your grandfather, though why you would want to is never explained.
But if you did murder your grandfather before the birth of your father then you would never be born, and therefore you could never go back in time and murder your grandfather. The paradox seems fierce enough, but there is a way around it. First though let's take a closer look at what travelling forward in time entails.In science fiction people travel for thousands of years to distant galaxies by virtue of deliberately induced coma, deep hibernation, cryogenic freezing or similar means. Shut down consciousness for the journey, and it doesn't matter how long it takes to get there.
Whether it's a hundred or a thousand years, if you're in a coma your mind is not gathering new data, but the rest of the Universe is. When you come out of the coma, when your consciousness is restored, the world has changed but you have not. "You" have moved in time from A to B without "you" changing, with the essential "you" intact, (if you define "you" to be your mind/consciousness -- a dubious proposition in my view).
In contrast, Going back in time is believed by some* to be impossible: that to go back in time would prevent going back in time from happening, in the first and last place, per the Grandfather Paradox.
(DIGRESSION ALERT: BTW I don't understand why it has to be the Grandfather Paradox. Why not simply the Father Paradox? Killing your father before your birth prevents you from being born just as effectively as killing your grandfather before your father's birth. End Digression.)
Nor does there have to be any killing for the paradox to exist: just to be where/when you don't belong introduces a change to the present and therefore to the future. So even if you could go back in time and very kindly refrain from killing your grandfather, just by being when/where you shouldn't be means you couldn't possibly be when/where you are, were, will be...
But in my view there is a resolution to the Grandfarther Paradox, if the Everretian “many worlds”/Multiverse interpretation of quantum physics holds true.
In the “many worlds” interpretation, Reality is continuously splitting into different “slices”, which in turn are themselves continuously splitting into new reality pathways or worldlines, in an infinitely iterative process of quasi-random, self-similar fractalisation (nah, just kidding -- made that last bit up!).
In one slice, I smoke a cigarette while writing this post. In another slice I do not. In another slice, I light a cigarette but stub it out immediately. In another slice, the cigarette smokes this post while typing me.
The point is that in an Everettian Multiverse, there could be a slice of reality – a worldline -- in which your grandfather exists but neither your nor your father exist, another slice in which all three of you exist, another slice in which none of you exist, etc. The existence of mutually contradictory worldlines is permissible only as long as there is no connection of any kind, causal or otherwise, between the various slices. They are all quarantined from each other for all time.
If you were to travel back in time and murder your grandfather before the birth of your father, you would create a new slice of reality: one in which neither you nor your father exist. This would be in addition to the slice of reality in which both you and your father exist. But there can never be any connection between the two slices: they are mutually exclusive. Still, the fact that there can’t be and is not a connection between two contradictory things doesn't mean that they can’t or don't both exist. They can and do, just as long as they have nothing to do with each other.
In contrast to the “many worlds interpretation” is the standard model, the "Copenhagen Interpretation".
- The Copenhagen Interpretation holds that there are many possible/potential worlds and worldlines, but only ever ONE is actually actualised (via the collapse of the wave function (a mathematical expression used to calculate the probability that a particle will be in a given location or state of motion at a given moment in time (which doesn’t exist))).
- According to the Many Worlds Interpretation, there are many possible/potential worlds and worldlines, and they are ALL actualised: they all exist.
* There's nothing in principle preventing the Laws of Physics running backwards in time: all known physical processes and events are reversible in theory and some believe have been reversed in practice at another phase / in other phases of the Universe's lifecycle. For example, there is nothing in the Laws of Physics preventing or outlawing a process whereby a shattered mirror falls up from the floor and reconstitutes itself whole upon the bathroom wall. The so-called "arrow of time" is a great mystery. Does time have an arrow, or is that an illusion? If it is, it's a real illusion: the illusion really exists.
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Hi
Its very Nice to do some judo with time theories. But sorry:-)
First prove me time does exist
I think thats inpossible.
Time is a concept an idea
A shared hypnotism in my thoughts.
So how about that :-).
Hi just another Martin,
I agree with your way of thinking about time. It is a concept, an idea, a word, a piece of language. We invented it in the first place. We think we know what the word "time" means, but that's only because we defined the word in the first place.
It's very hard to prove that time exists. It may be impossible, but it is at least very hard. For sure, there is no absolute time, only relative time: Einstein taught us that.
The meaning of time depends on the scale/context/stage on which it plays out. If the scale is the entire universe, then there is no time: everything happens at once, everywhere.
If I am as big as the entire Universe, then something that happens at the tip of the finger of my right arm happens at exactly the same time as something that happens at the tip of my finger of my left arm, even though there is an entire universe of space --- trillions of trillions of lights years --- between my arms.
And lastly, many people say that time is an illusion. Well, that may be. But if time is an illusion, it is a real illusion. The illusion really exists. It's more accurate to say, I think, that Time is not what we think it is, rather than to describe it as an illusion.
Thanks for your comments, and for stopping by. Cheers, MM
They can't make up their minds on the number of universes, dimensions, etc. before they pontificate. Meanwhile, politicians find it convenient to allocate lots of moolah for them to solve "fundamental" questions - supposedly far more important than other issues facing humanity.
Even in matters that are a lot less esoteric, the outlook for rationality is dim:
http://www.alternet.org/media/most-depressing-discovery-about-brain-ever
http://www.alternet.org/culture/theres-such-thing-human-nature-right
Hi mgeorge,
re the cosmologists, it's a strange sort of "post hoc" pontification.
It seems, to me at least, that what you DON'T do is think about how many dimensions the universe does/could/should have, then build a theory around that thinking, then conduct an experiment to test your hypothesis.
What you DO is build the theory first. Then you search for numbers/values that don't break the theory. Oh, and you never test your hypothesis: it is acknowledged that it is impossible to test the hypotheses of string theory experimentally.
The question about people and their brains is: was it ever thus? I think that peoples' rationality and the quality of their decision-making have both been roughly stable (at a very low base) for a very long time, but that it is only in recent times, 1) that it is becoming more evident, and easier to measure and identify due to improvements in testing techniques and an improving understanding of human psychology.
It's also easier to identify and measure because the effects are becoming very dramatic and plain to see, though apparently not for everyone. GRoupthink on a global scale at work.
The irony is that the more most of us come to depend on technology the less most of us understand it.
Thanks for your comments. Cheers, MM
mgeorge, sorry, couldn't resist the following hypothetical dialogue:
Cosmologist: The Universe consists of 11 dimensions.
Average Jo: How come we can't see them?
Cosmologist: They're very small.
Average Jo: Can't we use very powerful microscopes?
Cosmologist: Nah. They're rolled up too tightly: compactified you see.
One of the explanation of the double slit experiment, is that when the electron/photon is confronted with the choice of 2 slits. The electron/photon doesn’t split into 2, but rather it splices reality into 2. One for going through each of the slits, and hence a new universe with an alternate ending is created..
Its the same thing in concept, to time travel and killing the grand father.
I suppose with each and every decision we creates an alternate reality. In an infinite multi-verse.
And yet there is unity/cosmic-oneness. When un-observed the universe is an un-determined state.
Schrodingers’ car is both death and alive, until the box is opened.
Ricky, that's a really neat resolution of the "Many Worlds" and "Copenhagen Interpretation". Works for me. Thanks for expanding my knowledge. Cheers, MM
"Professional wrestling illustrates cooperative deception, which protects participants from extreme harm and thwarts tedium. We also see this in science, economics, business, war, politics and love." - Eric Weinstein, 2011
Theoretical physics allows a lot of leeway, without anyone laughing in your face, just like theology. The current consensus among the druids seems to be that backward travel in time, and even sending info backwards, is not possible.
Forward travel is on sound footing. It is old hat in science fiction, having taken off after H G Wells or Einstein. In a typical scenario, the travellers in their advanced ship bring salvation to a devastated Earth - a sort of Peace Corps of the future. In reality, it seems that those travelling even 100 years into the furure are likely to be irrelevant, except as temporary curiosities. Morover, we are from from even a conception of how spacecraft will even be shielded. As for sending info into the future, perhaps it can be used to fight censorship.
Hi mgeorge, I think it is cooperative deception that is actually bringing down extreme harm on the human race these days. We are cooperatively destroying everything in sight, and mainly deceiving ourselves that it's all gonna be alright on the night.
In professional wrestling, the basic dynamic is "pretend to hurt, and to get hurt, but in fact avoid hurting and avoid getting hurt"
In human culture today, the basic dynamic is "pretend to avoid hurting anything or getting hurt, but in fact get out there and cause as much hurt as you can as long as you get yours".
Re backward time travel, reminds me of the numerous examples of leading physicists who have said this or that is impossible (eg people travelling by train) only to be proven wrong.
The grandfather paradox is a fearsome beast. I'm not claiming that my little thought about using the many worlds model to resolve the paradox, actually resolves the paradox. But I think it does invite an answer to the question: Why can't all possibilities be true as long as they don't interfere with each other.
Thanks for your comments. Cheers, MM
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