If your going to think about time travel and how it really works I think you will also have to simultaneously tackle the "double slit experiment" the phenomenon where a single electron exists in an infinite number of superpositions, all modifying its own existence, while coming to rest as a collapsed wave form as a single particle.
The double slit experiment proves to us that a one-universe linear view of time doesn't work. For a particle to seemingly interact with ITSELF, then go back, pick one route, and hit the wall as a particle means that quantum events seem to thumb its nose at our notion of time.
I am not sure if that means that our notion of _time_ is completely broken. You're assuming an electron is a sphere, that goes like a tennis ball through one slit, then goes back in time through another slit to interfere with itself.
In Quantum Mechanics, there is no such thing as a _particle_ taking _this single path_. There is a continuum---that of the probability distribution of the position of the particle in a region of space, by the very axioms of QM. By definition, the statement "an electron exists here" has no meaning in QM.
That's the part that gets me: the particle seemingly interacting with itself. How do you know that it is indeed the same particle interacting with itself??!!
Because even when you fire electrons one at a time through 2 slits, the same wave pattern is seen to emerge. It appears as though a single electron explores every one of its options before it chooses a single route. The exploration process seems to leave footprints in a universe we can't see which causes the electron to behave strangely.
Basically, the idea is that if you are alive and capable of travelling backwards in time to attempt (directly or indirectly) your own murder, then your attempt has to fail by virtue of the fact that you're alive in the present. There's a nice thought experiment with a billiard ball here: http://en.wikipedia.org/wiki/Novikov_self-consistency_princi...
We all travel through time at varying speeds all the time:
There are two twin brothers. One brother goes on a space journey traveling at 99% of the speed of light. The space traveler stays on his journey for one year, whereupon he returns to Earth. On Earth, however, seven years have elapsed, so his twin brother is 7 years older at the time of his arrival. This is due to the fact that time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveler’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers.
Question: Did the traveler go forward in time or did the Earthbound brother go backward in time when they meet up later?
Question: How is it possible that one of the brothers shifted 7 years and yet they can meet in the same universe?
Are you asking to learn, or to provoke others to think?
If you were asking, reply and I'll dig up some links about how c is the speed of the universe and equals 1, spacetime and mass, and how velocity changes the relationship of time in spacetime.
I'd rather you answer the first one, how a person can move forward in time while staying in visual contact of the person staying behind. If you can answer that and prove it, then you will have made an amazing contribution to the understanding of the universe.
Two kids are on a merry go round, one in the center, one on the edge, the edge is traveling at .99 speed of light, when they communicate via cellphone, one voice sounds very deep and low, the other sounds fast like a chipmunk. Yet if you were to sample the sound relative to each point, you would hear a normal voice, because of some bizarre principle.
(I have to make some assumptions about your understanding of relativity.) The big breakthrough that Einstein made in general relativity was the 'relative' bit. There is no absolute thing of 'time', no universal tick of a clock. There is the time as experience by the traveller and the time as experienced by the brother. So there is no discontinuity that has to be merged when they meet.
It seems to me your question makes an implicit assumption that there is a universal tick that is thrown out of whack when the brothers meet. But there isn't, so the question is invalid.
I wonder if perhaps you regard space as one thing and time as a separate thing. It might help to throw that out and regard it as a four-dimensional object called spacetime.
For the merry-go-round, I'm not sure why you say one voice sounds low and the other high. They won't. Einstein's big thought experiment was to realise that the speed of light is constant no matter the speed of the observer.
As an aside, it is an unfortunate historical artifact that we call c the speed of light. It isn't. C is the "speed" of any massless particle in spacetime; it is unitless and equals 1. Photons are massless so they travel at c.
Why is the grandfather paradox the grandfather paradox and not the father/mother paradox? Why go back a generation more than is necessary? I've always seen it staged in this way and have never understood why.
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[ 1.7 ms ] story [ 34.4 ms ] threadWhat if the operator halts the collision when he detects said signal?
The double slit experiment proves to us that a one-universe linear view of time doesn't work. For a particle to seemingly interact with ITSELF, then go back, pick one route, and hit the wall as a particle means that quantum events seem to thumb its nose at our notion of time.
http://www.youtube.com/watch?v=DfPeprQ7oGc
If you want do some time traveling yourself, use a laser pointer and three mechanical pencil leads:
http://www.youtube.com/watch?v=UANVMIajqlA&feature=relat...
In Quantum Mechanics, there is no such thing as a _particle_ taking _this single path_. There is a continuum---that of the probability distribution of the position of the particle in a region of space, by the very axioms of QM. By definition, the statement "an electron exists here" has no meaning in QM.
Basically, the idea is that if you are alive and capable of travelling backwards in time to attempt (directly or indirectly) your own murder, then your attempt has to fail by virtue of the fact that you're alive in the present. There's a nice thought experiment with a billiard ball here: http://en.wikipedia.org/wiki/Novikov_self-consistency_princi...
There are two twin brothers. One brother goes on a space journey traveling at 99% of the speed of light. The space traveler stays on his journey for one year, whereupon he returns to Earth. On Earth, however, seven years have elapsed, so his twin brother is 7 years older at the time of his arrival. This is due to the fact that time is stretched by factor 7 at approx. 99% of the speed of light, which means that in the space traveler’s reference frame, one year is equivalent to seven years on earth. Yet, time appears to have passed normally to both brothers.
Question: Did the traveler go forward in time or did the Earthbound brother go backward in time when they meet up later?
Question: How is it possible that one of the brothers shifted 7 years and yet they can meet in the same universe?
If you were asking, reply and I'll dig up some links about how c is the speed of the universe and equals 1, spacetime and mass, and how velocity changes the relationship of time in spacetime.
Two kids are on a merry go round, one in the center, one on the edge, the edge is traveling at .99 speed of light, when they communicate via cellphone, one voice sounds very deep and low, the other sounds fast like a chipmunk. Yet if you were to sample the sound relative to each point, you would hear a normal voice, because of some bizarre principle.
It seems to me your question makes an implicit assumption that there is a universal tick that is thrown out of whack when the brothers meet. But there isn't, so the question is invalid.
I wonder if perhaps you regard space as one thing and time as a separate thing. It might help to throw that out and regard it as a four-dimensional object called spacetime.
For the merry-go-round, I'm not sure why you say one voice sounds low and the other high. They won't. Einstein's big thought experiment was to realise that the speed of light is constant no matter the speed of the observer.
As an aside, it is an unfortunate historical artifact that we call c the speed of light. It isn't. C is the "speed" of any massless particle in spacetime; it is unitless and equals 1. Photons are massless so they travel at c.
http://www.reddit.com/r/askscience/comments/g6zbd/if_we_depa...
http://www.reddit.com/r/askscience/comments/fu5io/help_me_un...