Cosmology Intelligent Design Physics Science fiction

Would backwards time travel unravel spacetime?

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File:Wooden hourglass 3.jpg
passage of time, imaged/S. Sepp

Astrophysicist Ethan Siegel offers two scenarios where it wouldn’t:

The second way out is to assume that the past isn’t written, and your actions do matter. The Universe, as it exists today, is not bound to the state its in right now if you travel back to the past. In a way, every action you take creates a new, alternate history for the Universe. You can kill your own grandpa before your parents are conceived; you can prevent your parents from meeting and falling in love; you can kill Hitler before World War II or assassinate Brutus and Cassius and Marc Antony before they assassinate Caesar.

In short, you can change history. The only thing you have to give up, then, is that the Universe you inhabit after traveling back in time is the same as the Universe you inhabit before you went back.

And in this new future, you may not even be born. You may simply have come into existence at the moment you arrived at your time-traveling destination. You would literally be a visitor from another Universe.Ethan Siegel, “Ask Ethan: Would Traveling Back In Time Destroy The Universe?” at Forbes

Except that there isn’t another universe; that one didn’t exist, remember? So then how could one have come to exist in order to go back?

Maybe it works better as science fiction.

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See also: Astrobiologist: Why time travel can’t really work

Carlo Rovelli: Future time travel only a technological problem, not a scientific one. Rovelli: A starship could wait [near a black hole ] for half an hour and then move away from the black hole, and find itself millennia in the future.

and

Rob Sheldon’s thoughts on physicists’ “warped” view of time An attempt to force complete symmetry on a universe that does ot want to be completely symmetrical

6 Replies to “Would backwards time travel unravel spacetime?

  1. 1
    FourFaces says:

    Ethan Siegel is a crackpot.

  2. 2
    vmahuna says:

    “Except that there isn’t another universe; that one didn’t exist, remember? So then how could one have come to exist in order to go back?

    Maybe it works better as science fiction.”

    Well, yeah, that’s the way I write MY Science Fiction.

    But part of the your problem is that you’re assuming ONLY ONE Time Traveler EVER existed. If we assume that many people have found ways to move “sideways” into one of the many alternate Timestreams over the many millennia, then the alternate timestream in which you arrive was already there BEFORE you arrived because its existence does NOT depend on your arrival. Also note that an alternate stream can exist not only as a “back-forth” (1 dimension stream), but as a parallel “left-right” stream or a parallel “up-down” stream (i.e., timestreams are “3 dimensional”). That is, you can move to a timestream that is 0 seconds younger than the one you start in, but 1 second “Left” or 3 seconds “Up”.

    And of course in any particular timestream, many, many details are different from what History was in your original timestream.

  3. 3
    bornagain77 says:

    Unrestrained imagination that is unconstrained by empirical evidence parading as scientific insight once again???

    Sigh!!

    Imagination has its place in science, in the forming of a hypothesis, but if that conjectured hypothesis cannot be established empirically by reference to the real world by empirical testing then it is worse that useless since it is, more likely than not, bound to mislead rather than enlighten. I see little to no reference to empirical testing in Siegel’s article. In other words, his article is virtually complete science fiction.

    For instance of ‘constraining imagination’ by empirical testing, Einstein utilized imagination in his formulation of Special Relativity which was later empirically verified.

    And Einstein’s Special Relativity, since it is now established empirically, certainly reveals far more to us about the true nature of time than Siegel’s unrestrained imagination does.

    Specifically, Einstein would often imagine what it would be like to travel the at the speed of light. His breakthrough insight for Special Relativity came when he imagined moving away from the face of a clock at the speed of light.

    Einstein: Einstein’s Miracle Year (‘Insight into Eternity’ – Thought Experiment 55 second mark) – video
    http://www.history.com/topics/.....racle-year

    Einstein imagined that if he were to move away from the face of a clock at the speed of light then the hands of the clock would be frozen and that time, as we understand it, would therefore come to a complete stop.

    This phenomena is known as time dilation. Time Dilation has now been empirically confirmed to be true for both Special and General Relativity:

    Time dilation
    Excerpt: Time dilation: special vs. general theories of relativity:
    In Albert Einstein’s theories of relativity, time dilation in these two circumstances can be summarized:
    1. –In special relativity (or, hypothetically far from all gravitational mass), clocks that are moving with respect to an inertial system of observation are measured to be running slower. (i.e. For any observer accelerating, hypothetically, to the speed of light, time, as we understand it, will come to a complete stop.)
    2.–In general relativity, clocks at lower potentials in a gravitational field—such as in closer proximity to a planet—are found to be running slower. (i.e. For any observer falling to the event horizon of a black-hole, time, as we understand it, will come to a complete stop.)
    http://en.wikipedia.org/wiki/Time_dilation

    More interesting still, the ‘reality’ of Time dilation is VERY friendly to the Christian’s belief in a eternal heavenly dimension that is above this temporal dimension.

    “For those of us who believe in physics. the distinction between past, present, and future is only an illusion, however tenacious this illusion may be.”
    – Albert Einstein – March 1955 – in the letter to comfort the family of a dear friend who had passed away. (of note: Einstein passed away the next month, in April of that same year)
    Einstein: A Biography, pg. 402

    “The laws of relativity have changed timeless existence from a theological claim to a physical reality. Light, you see, is outside of time, a fact of nature proven in thousands of experiments at hundreds of universities. I don’t pretend to know how tomorrow can exist simultaneously with today and yesterday. But at the speed of light they actually and rigorously do. Time does not pass.”
    Dr. Richard Swenson – More Than Meets The Eye, Chpt. 11

    Moreover, on further reflection of this ‘timeless’ nature of light, we find out many interesting things.

    For instance, we find that the only way it is possible for time not to pass for light, and yet for light to move from point A to point B in our universe, is if light is of a higher dimensional value of time than the temporal time we are currently living in. Otherwise light would simply be ‘frozen within time’ to our temporal frame of reference.

    Spacetime
    Excerpt: In 1908, Hermann Minkowski—once one of the math professors of a young Einstein in Zurich—presented a geometric interpretation of special relativity that fused time and the three spatial dimensions of space into a single four-dimensional continuum now known as Minkowski space. A key feature of this interpretation is the definition of a spacetime interval that combines distance and time. Although measurements of distance and time between events differ for measurements made in different reference frames, the spacetime interval is independent of the inertial frame of reference in which they are recorded.
    Minkowski’s geometric interpretation of relativity was to prove vital to Einstein’s development of his 1915 general theory of relativity, wherein he showed that spacetime becomes curved in the presence of mass or energy.,,,
    Einstein, for his part, was initially dismissive of Minkowski’s geometric interpretation of special relativity, regarding it as überflüssige Gelehrsamkeit (superfluous learnedness). However, in order to complete his search for general relativity that started in 1907, the geometric interpretation of relativity proved to be vital, and in 1916, Einstein fully acknowledged his indebtedness to Minkowski, whose interpretation greatly facilitated the transition to general relativity.[10]:151–152 Since there are other types of spacetime, such as the curved spacetime of general relativity, the spacetime of special relativity is today known as Minkowski spacetime.
    https://en.wikipedia.org/wiki/Spacetime

    One way for us to more easily understand this higher dimensional framework for time that light exist in is to visualize what would happen if a hypothetical observer approached the speed of light.
    In the following video clip, which was made by two Australian University Physics Professors, we find that the 3-Dimensional world ‘folds and collapses’ into a tunnel shape as a ‘hypothetical’ observer approaches the ‘higher dimension’ of the speed of light.

    Optical Effects of Special Relativity – video
    https://www.youtube.com/watch?v=JQnHTKZBTI4

    To give us a better understanding as to what it would be like to exist in a higher dimension, this following video, Dr. Quantum in Flatland, also gives us a small insight as to what it would be like to exist in a higher dimension:

    Dr. Quantum in Flatland – video
    https://www.youtube.com/watch?v=B5yxZ5I-zsE

    It is also important to note that although hypothetically traveling at the speed of light in this universe would be instantaneous travel for a person going at the speed of light (since time does not pass for that observer), this ‘timeless’ travel is still not completely instantaneous to our temporal framework of time. And is therefore not completely transcendent to our temporal framework.
    That is to say, speed of light travel, to our temporal frame of reference, is still not completely transcendent of our framework since light still appears to take time to travel from point A to point B from our temporal perspective. Yet, in quantum mechanics, instantaneous travel is not only achieved for the speed of light framework but instantaneous travel is also achieved in our temporal framework.

    Quantum Physicists Confirm Spooky Instant Correlations – Giulio Prisco – August 28th, 2015
    Excerpt: Researchers in the Netherlands, Spain, and the UK have confirmed in the lab that the weird instant correlations between remote “entangled” particles are real. The experimental result has important implications for both fundamental physics and future cryptography.,,
    https://hacked.com/quantum-physicists-confirm-spooky-instant-correlations/

    Looking beyond space and time to cope with quantum theory – 29 October 2012
    Excerpt: “Our result gives weight to the idea that quantum correlations somehow arise from outside spacetime, in the sense that no story in space and time can describe them,”
    http://www.quantumlah.org/high.....uences.php

    That is to say, the instantaneous travel of quantum information is instantaneous to both our temporal framework and the speed of light framework, not just the speed of light framework.
    Quantum correlations are not limited by time, nor space, in any way, shape or form, in any frame of reference, as light is seemingly limited to us in this temporal framework. Quantum correlations are truly instantaneous.

    Of particular interest to all this is that this discrepancy between what Einstein termed the ‘physical time’ of relativity and what philosophers termed ‘The Now’ of the mind is one of the primary reasons why Einstein never received a Nobel prize for Special Relativity.
    In fact, Einstein went so far as to say that “The time of the philosophers did not exist.” (and even said that ‘the experience of the now’ would never be a part of experimental physics),,

    Einstein vs Bergson, science vs philosophy and the meaning of time – Wednesday 24 June 2015
    Excerpt:,, Einstein said: “The time of the philosophers did not exist.”,,
    Bergson was outraged, but the philosopher did not take it lying down. A few months later Einstein was awarded the Nobel Prize for the discovery of the law of photoelectric effect, an area of science that Canales noted, ‘hardly jolted the public’s imagination’. In truth, Einstein coveted recognition for his work on relativity.
    ,,, In 1922, the jury was still out on the correct interpretation of time.,,,
    Just when Einstein thought he had it worked out, along came the discovery of quantum theory,,,
    Some supporters went as far as to say that Bergson’s earlier work anticipated the quantum revolution of Niels Bohr and Werner Heisenberg by four decades or more.,,,
    Was Bergson right after all? Time will tell.
    http://www.abc.net.au/radionat.....me/6539568

    This following video goes over that clash between Einstein and the leading philosopher of his day.

    Albert Einstein vs. Quantum Mechanics and His Own Mind – video
    https://www.youtube.com/watch?v=vxFFtZ301j4

  4. 4
    bornagain77 says:

    Yet, contrary to what Einstein thought was possible for experimental physics, ‘the experience of the now’ is now found to be very much a part of physical measurement.

    As the following researcher stated, “It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it,”,,, “The atoms did not travel from A to B. It was only when they were measured at the end of the journey that their wave-like or particle-like behavior was brought into existence,”

    New Mind-blowing Experiment Confirms That Reality Doesn’t Exist If You Are Not Looking at It – June 3, 2015
    Excerpt: The results of the Australian scientists’ experiment, which were published in the journal Nature Physics, show that this choice is determined by the way the object is measured, which is in accordance with what quantum theory predicts.
    “It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it,” said lead researcher Dr. Andrew Truscott in a press release.,,,
    “The atoms did not travel from A to B. It was only when they were measured at the end of the journey that their wave-like or particle-like behavior was brought into existence,” he said.
    Thus, this experiment adds to the validity of the quantum theory and provides new evidence to the idea that reality doesn’t exist without an observer.
    http://themindunleashed.org/20.....at-it.html

    Thus, contrary to what Einstein thought was possible for experimental physics, ‘the experience of the now’ is now found to be very much a part of physical measurement.

    It is also very interesting to note that many of the characteristics found in Near Death Experience testimonies are exactly what we would expect to see from what we now know about Special Relativity and General Relativity: For instance, many times people who have had a Near Death Experience mention that their perception of time was radically altered:

    Time and the Near-Death Experience
    Excerpt: Our time on earth seems like only a brief instance. Time in the spirit realm does not exist. By getting rid of the illusion of time from our minds, we have the power to expand our consciousness. We will realize that we are already living in timelessness right now.
    – per near death research dot com

    In the following video clip, Mickey Robinson gives his Near Death testimony of what it felt like for him to experience a ‘timeless eternity’.

    ‘In the ‘spirit world,,, instantly, there was no sense of time. See, everything on earth is related to time. You got up this morning, you are going to go to bed tonight. Something is new, it will get old. Something is born, it’s going to die. Everything on the physical plane is relative to time, but everything in the spiritual plane is relative to eternity. Instantly I was in total consciousness and awareness of eternity, and you and I as we live in this earth cannot even comprehend it, because everything that we have here is filled within the veil of the temporal life. In the spirit life that is more real than anything else and it is awesome. Eternity as a concept is awesome. There is no such thing as time. I knew that whatever happened was going to go on and on.’
    In The Presence Of Almighty God – The NDE of Mickey Robinson – video (testimony starts at 27:45 minute mark)
    https://www.youtube.com/watch?v=voak1RM-pXo

    And here are a few more quotes from people who have experienced Near Death, that speak of how their perception of time was radically altered as they were outside of their material body.

    ‘Earthly time has no meaning in the spirit realm. There is no concept of before or after. Everything – past, present, future – exists simultaneously.’
    – Kimberly Clark Sharp – Near Death Experiencer

    ‘There is no way to tell whether minutes, hours or years go by. Existence is the only reality and it is inseparable from the eternal now.’
    – John Star – NDE Experiencer

    As well, Near Death Experiencers also frequently mention going through a tunnel to a higher heavenly dimension:

    Ask the Experts: What Is a Near-Death Experience (NDE)? – article with video
    Excerpt: “Very often as they’re moving through the tunnel, there’s a very bright mystical light … not like a light we’re used to in our earthly lives. People call this mystical light, brilliant like a million times a million suns…”
    – Jeffrey Long M.D. – has studied NDE’s extensively
    http://abcnews.go.com/Nightlin....._gydvW8jbI

    The Tunnel and the Near-Death Experience
    Excerpt: One of the nine elements that generally occur during NDEs is the tunnel experience. This involves being drawn into darkness through a tunnel, at an extremely high speed, until reaching a realm of radiant golden-white light.
    https://www.near-death.com/science/research/tunnel.html

    In the following video, Barbara Springer gives her testimony as to what it felt like for her to go through the tunnel:

    “I started to move toward the light. The way I moved, the physics, was completely different than it is here on Earth. It was something I had never felt before and never felt since. It was a whole different sensation of motion. I obviously wasn’t walking or skipping or crawling. I was not floating. I was flowing. I was flowing toward the light. I was accelerating and I knew I was accelerating, but then again, I didn’t really feel the acceleration. I just knew I was accelerating toward the light. Again, the physics was different – the physics of motion of time, space, travel. It was completely different in that tunnel, than it is here on Earth. I came out into the light and when I came out into the light, I realized that I was in heaven.”
    Barbara Springer – Near Death Experience – The Tunnel – video
    https://www.youtube.com/watch?v=gv2jLeoAcMI

    And in the following audio clip, Vicki Noratuk, who has been blind from birth, besides being able to see for the first time during in her life during her Near Death Experience,,,

    Kenneth Ring and Sharon Cooper (1997) conducted a study of 31 blind people, many of who reported being able to see during their NDEs. 21 of these people had had an NDE while the remaining 10 had had an out-of-body experience (OBE), but no NDE. It was found that in the NDE sample, about half had been blind from birth. In all, 15 of the 21 NDEers and 9 of the 10 OBEers could see during their experience while the remaining participants either claimed that they did not see or were not sure whether or not they had seen.

    ,,, besides being able to see for the first time in her life, Vicki also gives testimony of going through a tunnel:

    “I was in a body, and the only way that I can describe it was a body of energy, or of light. And this body had a form. It had a head, it had arms and it had legs. And it was like it was made out of light. And it was everything that was me. All of my memories, my consciousness, everything.”,,, “And then this vehicle formed itself around me. Vehicle is the only thing, or tube, or something, but it was a mode of transportation that’s for sure! And it formed around me. And there was no one in it with me. I was in it alone. But I knew there were other people ahead of me and behind me. What they were doing I don’t know, but there were people ahead of me and people behind me, but I was alone in my particular conveyance. And I could see out of it. And it went at a tremendously, horrifically, rapid rate of speed. But it wasn’t unpleasant. It was beautiful in fact.,, I was reclining in this thing, I wasn’t sitting straight up, but I wasn’t lying down either. I was sitting back. And it was just so fast. I can’t even begin to tell you where it went or whatever it was just fast!” –
    Vicki’s NDE – Blind since birth –
    https://www.youtube.com/watch?v=e65KhcCS5-Y

    And in the following quotes, Mary Neal and John Burke both testify that they firmly believed that they were in a higher dimension that is above this three-dimensional world and that the reason that they have a very difficult time explaining what their Near Death Experiences felt like is because we simply don’t currently have the words to properly describe that higher dimension:

    “Regardless, it is impossible for me to adequately describe what I saw and felt. When I try to recount my experiences now, the description feels very pale. I feel as though I’m trying to describe a three-dimensional experience while living in a two-dimensional world. The appropriate words, descriptions and concepts don’t even exist in our current language. I have subsequently read the accounts of other people’s near-death experiences and their portrayals of heaven and I able to see the same limitations in their descriptions and vocabulary that I see in my own.”
    Mary C. Neal, MD – To Heaven And Back pg. 71

    “Well, when I was taking geometry, they always told me there were only three dimensions, and I always just accepted that. But they were wrong. There are more… And that is why so hard for me to tell you this. I have to describe with words that are three-dimensional. That’s as close as I can get to it, but it’s really not adequate.”
    John Burke – Imagine Heaven pg. 51 – quoting a Near Death Experiencer

    Moreover, besides heavenly experiences, there are also hellish experiences that also corroborate what we would expect to see from what we now know about General Relativity.

    To Hell and Back: The Dark Side of Near Death Experiences – Brent Swancer – May 25, 2016
    Excerpt: Nancy Evans Bush has estimated that one out of every five NDEs involve terrifying traumatic experiences such as black, cold voids, total sensory deprivation, yawning chasms of loneliness, prowling monsters, or indeed visions of an actual Hell, the description of which can vary wildly from person to person. In her book Dancing Past the Dark, Bush explains about these different permutations of Hell
    http://mysteriousuniverse.org/.....periences/

    Thus, in conclusion, Christians, far from being ‘anti-science’ as atheists often accuse Christians of being, can appeal directly to Quantum Mechanics, Special Relativity, and General Relativity to powerfully back up some of their core beliefs about God and the afterlife.

    2 Corinthians 12:3-4
    And I know that this man—whether in the body or out of it I do not know, but God knows— was caught up into Paradise. The things he heard were too sacred for words, things that man is not permitted to tell.

    Colossians 1:15-20
    The Son is the image of the invisible God, the firstborn over all creation. For in him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things have been created through him and for him. He is before all things, and in him all things hold together. And he is the head of the body, the church; he is the beginning and the firstborn from among the dead, so that in everything he might have the supremacy. For God was pleased to have all his fullness dwell in him, and through him to reconcile to himself all things, whether things on earth or things in heaven, by making peace through his blood, shed on the cross.

  5. 5
    ScuzzaMan says:

    Leaving the “many time streams” notion to one side for a moment – because as noted there’s no way it could ever be tested on the table – let’s consider a single time-stream universe, such as the one currently apparent to us, and the possibility of time-travel within that single stream.

    If you go back in time and change things so that “now” is significantly different between the two possibilities (the one that existed up to the moment before you time traveled, and the one that existed the moment after you changed things a thousand years ago) then there’s a question as to how things get re-arranged within the single stream. You see there’s an enormous amount of energy expended over a thousand years (indeed, there’s an enormous amount of energy expended across the universe every second) and the energy required to unravel a thousand years of universal history, and then re-run it forward, is quite prohibitively not going to be found in a small device you can fit in your local self storage unit.

    Or galaxy.

    OK, but you claim it is only the differential arrangements here on earth that need to be accounted for; your time-travel doesn’t affect the vast majority of the universe at all.

    Still the question remains: where does the energy come from to re-arrange things?

    The notion of the “space-time continuum”, the idea that space and time are related in a similar manner to electricity and magnetism, is one of the most pernicious theoretical cul de sacs of modern times. Dreams of “folding space” in order to avoid all that tedious traveling through it lead naturally, once space is coupled to time, to dreams of folding time … in order to avoid all that tedious traveling through it.

    And remind me of the old joke about the best way to time travel: just wait a while.

    But it aint necessarily so, and if it aint actually so then moving backwards in time requires reversing time, which requires all the energy in the universe, which means the energy threshold is never going to be reached by anything within this universe but could only in theory be reached by something outside of the universe, that has access to energy levels far exceeding those of this universe, combined with the technological capability to very finely control and direct such mind-boggling energies … well, one can easily see why people prefer to believe there’s some sly method of bypassing all that and just skipping stones through the streams of time.

    The whole exercise is a childish wish-fulfilment fantasy, wrapped in scientific jargon to give it a patina of intellectual respectability.

    Meh.

  6. 6
    ScuzzaMan says:

    … and then you get to the many-universes or many-streams time-travel variants, whereby every possible state exists somewhere, and uncountable new universes are created every moment.

    Where all that energy comes from is anyone’s guess. More fluctuations in the quantum foam perhaps.

    The ironies are thick and easily sufficient to collapse such speculations back into the non-existence they so richly deserve. One worth noting is that self-styled skeptics posit such fantasies with a straight face.

    Another is that these same people appear to think these schemes are more simple and elegant, a la Occam, than God.

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