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New Time Travel Simulation May Resolve ‘Grandfather Paradox’


New Time Travel Simulation May Resolve ‘Grandfather Paradox’

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On June 28, 2009, the world-famous physicist Stephen Hawking threw a party at the University of Cambridge, complete with balloons, hors d’oeuvres and iced champagne. Everyone was invited but no one showed up. Hawking had expected as much, because he only sent out invitations after his party had concluded. It was, he said, “a welcome reception for future time travelers,” a tongue-in-cheek experiment to reinforce his 1992 conjecture that travel into the past is effectively impossible.


But Hawking may be on the wrong side of history. Recent experiments offer tentative support for time travel’s feasibility—at least from a mathematical perspective. The study cuts to the core of our understanding of the universe, and the resolution of the possibility of time travel, far from being a topic worthy only of science fiction, would have profound implications for fundamental physics as well as for practical applications such as quantum cryptography and computing.


Closed time like curves

The source of time travel speculation lies in the fact that our best physical theories seem to contain no prohibitions on traveling backward through time. The feat should be possible based on Einstein’s theory of general relativity, which describes gravity as the warping of spacetime by energy and matter. An extremely powerful gravitational field, such as that produced by a spinning black hole, could in principle profoundly warp the fabric of existence so that spacetime bends back on itself. This would create a “closed timelike curve,” or CTC, a loop that could be traversed to travel back in time.


Hawking and many other physicists find CTCs abhorrent, because any macroscopic object traveling through one would inevitably create paradoxes where cause and effect break down. In a model proposed by the theorist David Deutsch in 1991, however, the paradoxes created by CTCs could be avoided at the quantum scale because of the behavior of fundamental particles, which follow only the fuzzy rules of probability rather than strict determinism. “It’s intriguing that you’ve got general relativity predicting these paradoxes, but then you consider them in quantum mechanical terms and the paradoxes go away,” says University of Queensland physicist Tim Ralph. “It makes you wonder whether this is important in terms of formulating a theory that unifies general relativity with quantum mechanics.”


Experimenting with a curve

Recently Ralph and his PhD student Martin Ringbauer led a team that experimentally simulated Deutsch’s model of CTCs for the very first time, testing and confirming many aspects of the two-decades-old theory. Their findings are published in Nature Communications. Much of their simulation revolved around investigating how Deutsch’s model deals with the “grandfather paradox,” a hypothetical scenario in which someone uses a CTC to travel back through time to murder her own grandfather, thus preventing her own later birth. (Scientific American is part of Nature Publishing Group.)


Deutsch’s quantum solution to the grandfather paradox works something like this:


Instead of a human being traversing a CTC to kill her ancestor, imagine that a fundamental particle goes back in time to flip a switch on the particle-generating machine that created it. If the particle flips the switch, the machine emits a particle—the particle—back into the CTC; if the switch isn’t flipped, the machine emits nothing. In this scenario there is no a priori deterministic certainty to the particle’s emission, only a distribution of probabilities. Deutsch’s insight was to postulate self-consistency in the quantum realm, to insist that any particle entering one end of a CTC must emerge at the other end with identical properties. Therefore, a particle emitted by the machine with a probability of one half would enter the CTC and come out the other end to flip the switch with a probability of one half, imbuing itself at birth with a probability of one half of going back to flip the switch. If the particle were a person, she would be born with a one-half probability of killing her grandfather, giving her grandfather a one-half probability of escaping death at her hands—good enough in probabilistic terms to close the causative loop and escape the paradox. Strange though it may be, this solution is in keeping with the known laws of quantum mechanics.


In their new simulation Ralph, Ringbauer and their colleagues studied Deutsch’s model using interactions between pairs of polarized photons within a quantum system that they argue is mathematically equivalent to a single photon traversing a CTC. “We encode their polarization so that the second one acts as kind of a past incarnation of the first,” Ringbauer says. So instead of sending a person through a time loop, they created a stunt double of the person and ran him through a time-loop simulator to see if the doppelganger emerging from a CTC exactly resembled the original person as he was in that moment in the past.


By measuring the polarization states of the second photon after its interaction with the first, across multiple trials the team successfully demonstrated Deutsch’s self-consistency in action. “The state we got at our output, the second photon at the simulated exit of the CTC, was the same as that of our input, the first encoded photon at the CTC entrance,” Ralph says. “Of course, we’re not really sending anything back in time but [the simulation] allows us to study weird evolutions normally not allowed in quantum mechanics.”


Those “weird evolutions” enabled by a CTC, Ringbauer notes, would have remarkable practical applications, such as breaking quantum-based cryptography through the cloning of the quantum states of fundamental particles. “If you can clone quantum states,” he says, “you can violate the Heisenberg uncertainty principle,” which comes in handy in quantum cryptography because the principle forbids simultaneously accurate measurements of certain kinds of paired variables, such as position and momentum. “But if you clone that system, you can measure one quantity in the first and the other quantity in the second, allowing you to decrypt an encoded message.”


“In the presence of CTCs, quantum mechanics allows one to perform very powerful information-processing tasks, much more than we believe classical or even normal quantum computers could do,” says Todd Brun, a physicist at the University of Southern California who was not involved with the team’s experiment. “If the Deutsch model is correct, then this experiment faithfully simulates what could be done with an actual CTC. But this experiment cannot test the Deutsch model itself; that could only be done with access to an actual CTC.”


Alternative reasoning

Deutsch’s model isn’t the only one around, however. In 2009 Seth Lloyd, a theorist at Massachusetts Institute of Technology, proposed an alternative, less radical model of CTCs that resolves the grandfather paradox using quantum teleportation and a technique called post-selection, rather than Deutsch’s quantum self-consistency. With Canadian collaborators, Lloyd went on to perform successful laboratory simulations of his model in 2011. “Deutsch’s theory has a weird effect of destroying correlations,” Lloyd says. “That is, a time traveler who emerges from a Deutschian CTC enters a universe that has nothing to do with the one she exited in the future. By contrast, post-selected CTCs preserve correlations, so that the time traveler returns to the same universe that she remembers in the past.”


This property of Lloyd’s model would make CTCs much less powerful for information processing, although still far superior to what computers could achieve in typical regions of spacetime. “The classes of problems our CTCs could help solve are roughly equivalent to finding needles in haystacks,” Lloyd says. “But a computer in a Deutschian CTC could solve why haystacks exist in the first place.”

Lloyd, though, readily admits the speculative nature of CTCs. “I have no idea which model
 is really right. Probably both of them are wrong,” he says. Of course, he adds, the other 
possibility is that Hawking is correct, “that CTCs simply don't and cannot exist." Time-travel 
party planners should save the champagne for themselves—their hoped-for future guests seem 
unlikely to arrive.

  • Anatole Wilson · Top Commenter · Pittsburgh, Pennsylvania

    Still sounds like “a big ball of wibbily wobbly timey wimey…stuff” is as good an explanation as any.
  • Richard Guy · Hunterdon Central Regional High School

    If I travel back in time, I will have to make a note not to read this article again.
  • Ray Thackeray · Top Commenter · Bangor University

    There was a young fellow named Bright,
    Who could bicycle at the speed of light.
    He set off one day,
    In a a relative way,
    And came home the previous night.
  • Brian Sienkowski · Top Commenter

    Oh, people showed up for the party, just not in this universe.
  • Fred Bullmer · Top Commenter · Pendleton, South Carolina

    Stephen Hawking and his caterers are TELLING us no one showed up. If they let is slip that someone from the far future showed up then spilling the beans would create the wrinkle in time that could prevent future events… Just Saying… 😉
  • John Scotto · Top Commenter · International Affairs at Universal Exports

    Did they forget about slingshotting around the sun?
  • Darrell Burgan · Top Commenter · The University of Texas at Austin

    My prediction is that some major discoveries relating directly to the notions of causality, determinism, and the feasibility of time travel will be made in the next few decades. There are several avenues of science – not just physics, but also mathematics, theoretical computer science, systems theory, and others – that are all converging on the same fundamental set of problems. It’s going to be fascinating, whatever they discover.
  • Nashida Rikiishi

    Wow, I really enjoyed reading this article, though I’m not sure I understand what these fellows are really saying. I’m not a mathematician by any stretch and therefore realize my short comings to fully comprehend this
    • Vamroc M Sylar · Top Commenter

      Deutsch’s model of CTCs is saying that the moment a time traveler goes back he creates a divergent reality and it doesn’t matter if the grandfather dies because he’s not YOUR grandfather he is the grandfather of the possible “you” in that new reality. The other guy is saying that if you killed your grandfather suddenly you might not remember anything because you haven’t been born but their exists the possibility of someone preventing you from going back which is how the paradox is avoided.
    • Paw Paw Simmons · Top Commenter · Liptovský Hrádok

      Thanks Vam…..Simply put….Very nice.
  • Christopher Charles Currie · Providence, Rhode Island

    The problem with quantum mechanics is that it is a statistical approach for measuring reality. So far, it has successfully been used to describe some kinds of physical phenomena more accurately than deterministic theories (mathematical formulas), because those mathematical formulas are based on assumptions that are not entirely accurate. For example, the speed of light through outer space is often assumed to be constant, but it isn’t, because “outer space” is far from being a pure vacuum. Most cubic meters of outer space contain at least a few atoms of hydrogen, many more sub-atomic particles, plus gamma rays and light rays crisscrossing each other from virtually all directions. And when you consider how many cubic meters of outer space a light ray has traveled through (while going from one galaxy to another), it is quite reasonable to assume that outer space itself acts somewhat like a prism (thereby creating a “red tint” which some scientists speculate to be evidence supporting their “big bang theory.”) Also, if all of those galaxies are accelerating away from each other (as “big bang” theorists claim), then how can the Hubble Telescope photograph galaxies that at colliding with each other?

    On the other hand, quantum mechanics has been used to support claims that a particle can be “a two different places at the same time”, but that may simply reflect that fact the slice of time used for that experiment was too large to accurately measure where that particle actually was.

    So we need to re-examine the fundamental assumptions that are being made in order to create such mathematical models. Is it the speed of light that is constant or is it a precisely measured incremental advancement of time that is really the constant? If the advancement of time (which is part of the “speed of light” formula) is in fact what is really constant, then all this talk about “bending the fabric of space-time) leaves much to be desired.

    • Scott T. Currie · South Paris, Maine

      …if I only had a little more time…..
    • Dre Day · Top Commenter · Technical Support at ThreatTrack Security

      “On the other hand, quantum mechanics has been used to support claims that a particle can be “a two different places at the same time”, but that may simply reflect that fact the slice of time used for that experiment was too large to accurately measure where that particle actually was.”

      The double slit experiment confirmed that particles can be two places at once. The wave/particle duality makes it look that way because when the particle this something (being observed) parts of the wave overlaps and cancels out while other parts of the waves reinforce each other.

      Also accurate measuring a particle gets harder not because of time, but because of the amount of energy needed to observe it. At some point, the light waves you use to try and measure both position and velocity will disturb the light wave of the particle and all you’ll come up with is probabilities of where it could be (Heisenberg Principle)

      Also, as for the big bang theory and colliding galaxies, I heard it somewhere that the gravitational pull of the two galaxies (in the relatively local sense)exceeds the force of the expansion (Which most physicists will attribute to dark energy vs dark matter) Because the force of the expansion is so weak at greater distances, it doesn’t really affect a galaxies that are relatively close.

  • Jerry Greenberg · Top Commenter · Engineer at Various media and R&D for electronic systems.

    There are valid theories about how time travel can be achieved. At the sub atomic particle level time shifting of specific particles have been achieved. This involved very large amounts of power and usage of particle accelerator facilities.

    If we look back to the early to mid 1800’s when existence of radio waves may be possible was only a theory by some scientists of the time, there were others commenting that radio waves would be impossible for any human to make. Then when the scientists who were working to make radio waves said these waves may be able to carry intelligent information they were ridiculed and regarded as to being fools.

    If we look to the early 1900’s radio broadcast with human voices in real time were being used, and real time pictures (television) was being experimented with.

    Before television existed there were engineers and scientists saying this type of medium would be impossible to accomplish. Once accomplished there were engineers saying it would never be practical and reliable to have in the home.

    Now we move up a hundred years or so, we can have super high definition television fit in the palm of a person’s hand, where we can see live or recorded pictures instantly from any part of the world.

    With television we can look back in to the past because of film, video tape, and now digital recording on a chip that can be made smaller than a human finger nail.

    As for time travel, it is interesting that some governments are pouring in a lot of money. This research is being kept very quiet, and is titled under other types of research projects. It is unfortunate that there are people making huge exaggerations about time travel and its existence to make profits from the excitement and fascination with this subject.

    Just like everything else that has been accomplished, with all that has been done in various types of science and industry, we have to be opened to all possibilities. Maybe in a few hundred years from now tele-transport and time travel will be common place!

  • Kenneth Glen Price · Top Commenter · College of San Mateo

    My hypotheses on this subject is, travel to the future it seems would be the impossible journey as for the future has not yet happened. The future does not exist for any one person, only the now and the past.
    It would be like trying to climb a set of stairs in a building that has not been built yet.Since the past has happened, then time travel should let one be able to interact with past events.

    As to the paradox, well since you are here, you did not kill your grandfather. Most likely you would not be able to do so, as it had not happen in your time line or you would not exist. Doing so may start a divergent time as as others have stated, but that would not effect you.

    This is all conjecture though, with out a time machine to test the hypotheses.

    • Richard Ustick · Top Commenter

      Your basic premise may be wrong, and with that your whole argument would fall apart. You assume the future has not happened yet because you view time as linear only. You live it as a line so everything must be that way. You are Cyrano De Bergerac floating to the moon on bottles of morning dew because if there is air down here, then certainly there is air up there.
    • John Timmons · Works at Retired

      My brain still ‘urts!
    • Napoleon Smith III · Top Commenter · Scottsdale, Arizona

      Uh. We have already proven hay time travel is possible to the future. Any man that has gone into space has actually travel in future on a micro scale. As you get closer to the speed of light, time in fact travels slower for you than other outside the travel
  • Chris Gleave · · Newburg High

    well i think that the fact the we are constantly moving or falling through space as they like to put it then how are you going to send anything back in time say you want to even send me back 15 minutes well 15 minutes ago i was 10k revolutions to the left not to mention how far we have moved in space even a fifteen minute jump might send me 1500 feet into the air just to come crashing down
    and to take one body move it through a length of time …. i might end up at the edge of our solar system … do i get a suit for this trip?
    • Brad Mareci · Top Commenter

      you would have to calculate relative distance to a gravity well.
    • Richard Ustick · Top Commenter

      So if you travel in time, but NOT in space, then you would be in a lot of trouble going back even one day. The earth woudl not be in this location in its orbit.
    • Paw Paw Simmons · Top Commenter · Liptovský Hrádok

      Ya know?….people ought to discriminate this topic into catagories of physics and math and metaphysics and then social-science and politics. Fact: So far we haven’t traveled back in time in any way physically. Fact: so far we can do it easily on paper. Fact: if you look at the middle east?…those folks haven’t made it to the year 1900 as yet !!!!!, all we need to do to travel back in time is to go there. Fact: as of the year 2014?….this country has fallen back in time about 35 years to the year 1979, what with our employment crisis and our political crisis’ and our govermentmental woes….I mean geeeeeesh.!!!!! What is goin on man?
  • Frank Scoblete · Author at Book writer

    I just spoke with my great, great, great, great grandson who is a time traveler and he said not to worry about anything. I trust the guy.

    Frank Scoblete author of “Confessions of a Wayward Catholic”

  • Robert Dams · Houston, Texas

    I believe that the universe we live in is like a sheet of glass. When you look at it in the front it is a 2d surface but as you turn it you see the 3d perspective. In this dimensional shift if you were to travel back in to time then you would wind up in a parallel universe that may hold another choice you made in your life and the outcome it entails. Thus it is possible to go to another dimension in time on another sheet of glass but not make changes to the existing dimension you came from.
  • Jerry Engelbach · Top Commenter · Pátzcuaro

    Thought experiments are fun.

    But real time travel would destroy science fiction, a great loss to literature.

    However, we “travel” through time when we observe the distant universe, since we are seeing events that occurred many millennia ago.

    Thus, it may someday be possible to capture light rays from the past and thus observe it.

    • Paw Paw Simmons · Top Commenter · Liptovský Hrádok

      Uh,,,Jerry,..You do keep up with astronomy don’t you?…and you know about all the galaxies that are hundreds of thousdands if not millions of light years away?…..we are observing them in the distant past…..just pointing that out.
  • Timothy Weaver · Top Commenter

    If I was an astronaut, I would definitely show up, since, according to special relativity and atomic clocks, they would have traveled to the future even if the shift forward in time was measured in millionths of a second.
    • Dw Schoenthal · Top Commenter

      Big difference between travel into the future and travel into the past. SH conjectured that travel into the past is effectively impossible, future is possible however would require more energy then our Sun will ever put out to move 1 gram 1/100 of a second into the future.
    • Darrell Burgan · Top Commenter · The University of Texas at Austin

      Dw Schoenthal I disagree. Each one of us is moving into the future expending no energy at all. It requires energy to change the rate of movement, but the ground state is not motionlessness.
    • Dw Schoenthal · Top Commenter

      Darrell Burgan I guess I forgot relative to the timeline the rest of us are on. However the total amount of energy spent in the Universe in that 1/100 of a second is even larger.
  • John Crane · Top Commenter · Works at AT&T

    The paradigm of cause and effect already break down. If I instigate a cause C in order to produce effect E, which is really cause and which is really effect?

    The desire to produce effect E, is the cause of cause C.

  • Lloyd Walsh · · Top Commenter · PennValley College KC MO.

    aren’t we already time travelers so to speak, since we are traveling into the future
  • Eric Burgess · Top Commenter · Baker MI

    Funny, I don’t remember that blue Police box being there before.
  • Richard Anderson · Top Commenter

    I’ve long been jealous of persons with job titles such as, “Theorist”. Someone gets paid to think up things that are “statistically possible”. I can and do that all the time for free!

    Seriously, though, my belief system is based on science, and rejects religious teachings which require “blind faith”, based on anecdotal “evidence”. Many recent theoretical scientists are putting forth ideas that would have been considered science fiction decades ago. My problem is that “theoretical” literally means conjecture to a certain extent. Granted, conjecture based on mathematical evidence, but conjecture nonetheless. My point being, the line between religion and science, in their explanatory roles concerning the universe has become increasingly blurred – though I remain on the science side of the equation, due to factual evidence being essential to even theoretical ideas.

    BTW – “Theo” as a preface means, “relating to God or deities”, so that would suggest a philosophical component to physics.

    • Dre Day · Top Commenter · Technical Support at ThreatTrack Security

      Theorists do have some pretty important work. They can provide benchmarks for future experiments once we have the tech to do so. They could also lend ideas to problems that aren’t thought about at the moment. They are very intelligent individuals who can think outside the box of physics and not get stuck in tunnel vision. Remember Einstein’s GR and SR were theoretical for a long time until his predictions were actually observed.

      Sure some theories turn out to be debunked but I wouldn’t go so far as to say anyone can do it. Even theoretical, it has to be substantiated by a very pedantic community to be accepted.

  • Edward Schillenger · Top Commenter

    I wish someone smarter than I could explain this to me. If ya’ll will forgive my arrogance, my reading comp skills are pretty top-notch, and I love science and subjects such as this, but it’s tough for me to actually visualize and comprehend exactly what’s going on and why the grandfather paradox actually get’s resolved. I’m still wondering why there can’t be multiple timelines…. when has that been disproved? Such a thing instantly solves a bunch of time-travel paradox’s. You CAN go back in time and kill your grandfather, because as soon as you go back in time, technically the person being killed is no longer YOUR grandfather. Great, now I feel the need to go smoke a joint……..
  • Dave Schutt

    for ever change thus creates an alternate reality. like a fork in the road. so if you went into the past then YOUR future would change while everyone from THAT alternate reality would go unchanged. so the idea of changing the past for the sake of mankinds future is irrelevant. It would in essence only change your future. So the whole idea of time travel and changing the past is just selfish. **BUT**…traveling to the future to prevent things from happening for people from your timeline would then benefit because they have yet to experience any of those events. Like a train switching tracks at the last second to avoid a collision.
  • Paw Paw Simmons · Top Commenter · Liptovský Hrádok

    You do realize this is the year 2014?……even now, talking, even from Hawkings is still dribble on this subject…we haven’t gone to the Moon permanently and we haven’t even gone to Mars yet. We haven’t transported any kind of matter from one place to another using a particle matter beam or even invented a warp drive engine for space travel. It is however somehow just romantic as hell to talk about science fiction as if it was real…Oh Sleep..per chance to dream !!!!! Everybody go to sleep.
  • Clear Fog · Top Commenter

    If time is infinite, then there will be an infinite number of time travelers and they will visit each second of time an infinite number of times. Don’t try to raise the argument that they may not want to, if time is infinite, atoms (or leptons and quarks if you will) will randomly assemble themselves into an infinite number to time machines with and infinite number of time travelers. Where are they?

    If time is not infinite, we need a new theory of time and therefore a new theory of time travel.

  • John Marker · · Top Commenter · San Diego, California

    as for the grandfather paradox, there is none. IF there was such a thing as a space time continuum, and time travel was a reality, traveling back in time breaks the continuum. The continuum runs throughout a person’s lifetime, and when the life TIME is broken by time travel, there is no longer any connection between the future person and the past person. You could even kill your past self in time travel, and it would not effect the other you.
    • Brian Dickey · Lab Technician at Schlumberger

      Agreed!!! Nothing in the universe suddenly “blinks out of existence”, time travel or not. Traveling back in time and killing your grandfather doesn’t suddenly make you fade into nothingness, or spontaneously “wink out” it just turns you into someone who just killed a guy!
    • Ray Thackeray · Top Commenter · Bangor University

      Wrong. You need to read the definition of paradox.
    • Bob Plugh · Top Commenter

      You are still thinking of time as a linear thing and not an object like a coordinate in three dimensional space. Nothing prohibits me from taking a piece of paper and folding it such that the piece of paper intersects itself multiple times. Einstein postulated space-time – that is – 4 dimensions. That fourth dimension only appears to be different to us, but in reality, it must act just like the other three dimensions. So, instead of having a piece of paper that represents x,y,z, think of it as representing x,y,t where t is time. When you fold it now, the “t” coordinate can intersect in multiple places so, indeed, there is no lack of continuity.
  • Chris Stutts · Jet-propelled roller-skate designer at ACME

    There was a novel, well-received, written a couple decades ago by physicist Gregory Benford. In his story, the guys doing the experiment think that the one-photon switch just described in the article sort of hangs halfway between off and on, jittering between the two states. It wasn’t clear to me what observer could see it toggling; who possibly exists that can see the switch move?
  • Steven Brumfield

    So pushing it, if there is a 50/50 chance of encountering grandpa, you could basically say that quantum physics will insure that you couldn’t interact with your grandpa at all . No matter how hard you tried , or would send you back. before you could, or create an alternate universe to avoid a paradox. Of course if you could kill grandpa then that would prove the rumors that grandma was unfaithful true.
  • Jeff Conway · Top Commenter

    Maybe no one showed up to his party because they considered him to be a boar and had better ways to spend their time. Maybe time travel won’t be realized until so far in the future that no one knew of it or him. Maybe the human race simply doesn’t survive long enough to realize time travel.
  • Will Martin · Top Commenter · Southeastern Massachusetts University

    I went to sleep on Tuesday.. Woke up on Wednesday.. But I thought it was still Tuesday all day.. So i went 1 day into the future.. But was temporally existing in the past.. Therefore, I went forward *and* backwards in time in a very small space-time contuum…
  • Andy Stanton · Top Commenter · Forest Hills High School

    The article postulates that time travel may be possible for QUANTUM particles only. There’s no scientific theory that would permit non-quantum matter, such as a human being, to travel in time.
  • George Freiberg · Top Commenter · Works at Dollar Tree

    If I time traveled to the future, do I not run the risk,(knowing not the inevitable date my death will occur in the future), of arriving at a time after I have deceased, and have I then in fact, short circuited my possible life span, BY TRAVELING BEYOND IT?
    • Dre Day · Top Commenter · Technical Support at ThreatTrack Security

      No because you’re still you that was propelled into the future. You cant encounter yourself in the future because you haven’t been there yet. That would mean that all time is predetermined. Science fiction likes to play around with encountering a future you from a different timeline that is not yours. If you were able to do that, you would not exist in your timeline until you go back.
  • James Clovispoint

    It seems to me that if a future time traveler was expected at Dr. Hawkins’ party, he should have sent out invitations to a (anonymous at least) guests through the mail so that such a guest may one day receive it in order to show up at the party. No?
  • Steve Peters · Top Commenter

    Been there ~ done that ~ done that ~ been there, been here ~ done thatt paradoxically a new wrinkle ~ Have we not learned our guys/gals in space have been time traveling all along??
  • Mike Schmitt

    They didn’t feel they needed to meet him and interfere with our history since he was wrong. They didn’t come to my party so time travel is impossible. I wish the religious people thought like that.
  • Mark Schwartz · Top Commenter · Works at Facebook Blows

    If Schrodinger’s Cat (we’ll call him “Mr. Muffins”) travels back in time to run away before being shoved in a box to either die or not die, wouldn’t he be better off simply wishing he were dead?
  • Humphry Trivargo · Top Commenter

    I go with the multi-verse theory myself. The grandfather you kill will not be your own, it will be one of your other self’s grandfather, so no paradox has occured..
  • Kenneth Whitmire · · The University of Texas at Austin

    I read ‘entanglement’, ‘cat-in-the-box paradox’, ‘quantum computing’ and ‘chronology protection conjecture’. Nothing new here.
  • Robbie Raymo · Top Commenter

    the body vehicle is a STARGATE, intelliegence never proofs anything yet intellect allows us to observe beyond the solidified dispositions
  • Jake Ward · Top Commenter

    Anything we set our minds to is possible if we give it time.. Stephen Hawking will learn a great many lessons the day he wakes up and sees he does not know everything.
  • Jim Pappas · Colorado Technical University

    I do not care whether or not time travel is possible. What I do KNOW though, is that it is a really bad idea to do it. So, if you can figure out a way to travel back to the past, DON’T DO IT.
  • Dave Wicks · Burney, California

    time travel is fun at parties, but not realistic, or possible EVER, and these “Brainiacs’ all know it.
  • Don Mockaitis · New Mexico State University

    Why would anyone want to go back and kill their grandfather? Perhaps go back and kill Hitler while he was still young.
  • Gary Carter · Works at The Home Depot

    if time traveling was a possible. i wouldn’t go see Steven. I would go watch important time events.
  • Maziar Malek · Top Commenter

    One wonders if the author has any plans of making a trip to the event horizon of a black hole and meet one of his ancestors!
  • Dw Schoenthal · Top Commenter

    The past no longer exists as someplace to go to according to SH. That in and of itself makes it impossible to go to.
  • Roger Marshar · Top Commenter · Milwaukee, Wisconsin

    If people did show-up, he would have to lie and say they didn’t, to preserve the time line.
  • Corey Baun Metallic · Campbellton, New Brunswick

    He got the idea from Big Bang Theory when they were going over the Roommate agreement
  • Mikelodean Centeio · Top Commenter · Clipper at Toenail clipper

    So is this in laymans terms? I still don’t get it. I understood up until after the experiment.
  • Razooka Joe · Top Commenter

    Gotta get back in time
    Gotta get back in time
    Get me back in time
  • Caleb J Fielding · Top Commenter · Victory Baptist Bible Collage

    if you could time travel would you want to go to a party nobody else went to?
  • Nathan Allen Bobo · Top Commenter · Olentangy High School

    What if I told you you are time traveling right now?
  • Michael Zydzik · Top Commenter · Creative Director at Creative Director at Fusionfarm

    fascinating.. but now my head hurts
  • Gary Gadd · Top Commenter

    If time does exist, someone may eventually create time travel. If time is merely an artificial measure of the means by which we perceive sequential events, nope.
  • Charles Fourness · Wayzata, Minnesota

    One more sorry. Then devise a means to map the expansion of the universe and our rotations in it, back to a specific point in time? Program that into the crystal too, on to the photon, into the hole, and magically back to 600ad lol
  • Steve Benton · Top Commenter · National Labor College

    Cool. Maybe real soon they can fast forward Kansas into the 21st Century.
  • Charles Fourness · Wayzata, Minnesota

    Now I don’t have all the facts mind you, and am going speak crazy but… Wouldn’t it be interesting if they took the experiment, with quantum entanglement and used it with this time travel idea? They spank a qubit of information onto a photon but using this-
    • Dre Day · Top Commenter · Technical Support at ThreatTrack Security

      The only problems with QE is the Heisenberg Uncertainty Principle. It’s almost impossible to know what state the pairs are in because the more precisely you measure a particle, the more you disturb it. You cant know its position or velocity at any one time. It’s called the EPR paradox or Einstein, Podlosky and Rosen.
  • David de Medicis · Top Commenter · Alabama

    My brain just exploded.
  • Peter O’Loghlen · Top Commenter

    My head hurts.
  • Richard Somers · Top Commenter

    How does he know if no one showed up? A time traveler could have showed up. Then later decided not to show up. So he or she went back in time not to show up. Therefore not showing up at all.
  • Nelson Silva · Passaic High School

    Today, using a telescope an astronomer sees stars
    being born or dying in events that happened millions
    of years ago. I do not know, but it seems what happens
    now is happening forever( that’s to the senses of an observer)
    • Bob Plugh · Top Commenter

      We are only seeing the light from the even that occurred millions of years ago. If you could instantly transport to the origin of that light you would view the current state of that object.

      As that light travels it also dims since it is being dispersed over a larger and larger sphere so that “event” does not appear as bright here as it did at any distance closer to the originating object.

    • Dre Day · Top Commenter · Technical Support at ThreatTrack Security

      IF it’s still there.

Supersonic subs look to cross the Pacific in under two hours, research

Supersonic subs look to cross the Pacific in under two hours




The distance between Shanghai and San Francisco is around 6,135 miles (9,873 km), and a team of scientists aims to make that trip possible in 100 minutes. Researchers at Harbin Institute of Technology’s Complex Flow and Heat Transfer Lab have developed new tech that allows submarines to traveling a crazy-high speeds beneath the water. The solution? Create an air “bubble” of sorts that leverages supercavitation, a technology applied to torpedoes, to reduce drag caused by water while in route. Theoretically, this means that the vehicles could reach the speed of sound underwater (around 5,800km/h or 3,694 MPH while submerged), reducing the travel time between the aforementioned cities to under two hours.

As you might expect, several issues face the implementation of the tech — like the fact that the sub would have to be launched at a high rate of speed to maintain the requisite air bubble. Traditional steering methods (read: rudders) wouldn’t work inside the air pocket either, as they wouldn’t have water to push back on. However, to combat the two conundrums, researchers say allowing a vessel to constantly “shower” a liquid membrane on its surface would reduce drag until it gets up to speed. From there, the same membrane creates the supercavitation and controlling the friction on it would aid navigation. Even with those issues under control, a rocket engine with a range that would enable such long trips still needs to be developed. So for now, you’ll have to stick to spending several hours flying the friendly skies.

Update: The headline of this story has been updated to reflect that the research into the supersonic tech is on-going and theoretical. It wasn’t intended to be misleading, but I can certainly see how it was.

[Image credit: Sam Yeh/AFP/Getty Images]


Water-Based Tractor Beam Could Confine Oil Spills, Control Floating Objects

This Water-Based Tractor Beam Could Confine Oil Spills, Control Floating Objects


We may be one step closer to building a real-life tractor beam.

Scientists in Australia have developed a water-based tractor beam, and while it’s not exactly the marvel made famous by “Star Trek,” it’s pretty darn impressive. It can control water flow patterns, maneuver floating objects and could even help confine oil spills.

A tractor beam is a popular term which, I think it captures quite well the basic principal,” lead researcher Dr. Horst Punzmann, an engineer at the Australian National University in Canberra, told the Australian Broadcasting Corporation. “You put an object there and it propagates, it floats backwards to the source of the wave.”

And Punzmann and his team were able to do much more than make an object change course and travel backward.

“We’ve managed to manipulate floating objects to move toward the wave, to move in the direction of the wave or to keep them stationary in the flow,” Punzmann explains in a video released by the university (see above). It shows researchers using the wave-manipulation device to steer a ping-pong ball around a tank.

To manipulate the ball, researchers first determined the size and frequency of the waves required to move it. Then they observed the surface movement produced by the waves.

“We found that above a certain height, these complex three-dimensional waves generate flow patterns on the surface of the water,” Dr. Michael Shats, a professor in the university’s College of Physical and Mathematical Sciences, said in a written statement.

Shats added that existing mathematical theories cannot describe the currents produced by the larger waves.

“It’s one of the great unresolved problems, yet anyone in the bathtub can reproduce it,” he said. “We were very surprised no one had described it before.”

While the water-based tractor beam is new, Punzmann’s team is not the first to propose the idea of a working tractor beam. NASA previously awarded scientists a $100,000 grant to investigate particle-moving technology.

And in 2012, researchers in Singapore detailed how a special type of laser, called a Bessel beam, might be used to push an object backward toward the beam’s point of origin. In 2013, a team in Scotland debuted a working prototype capable of moving minuscule particles.

The new research was published in the August 2014 edition of the journal Nature Physics.


Meet the Starship Enterprise of the Sea

A French architect’s audacious plans for a ship that will change the ocean exploration is done.


Garnering comparisons to Star Trek’s starship Enterprise, the SeaOrbiter is the brainchild of French architect Jacques Rougerie. Set to begin construction this spring, the 190-foot-tall semisubmersible vessel will be the culmination of nearly 30 years of Rougerie’s research and development.

Six of the SeaOrbiter’s 12 floors are below sea level, allowing for uninterrupted underwater observation. Although the ship’s main mission is to research the biodiversity and climate of the sea, the real goal for Rougerie is to give the public a better understanding of how crucial the ocean is to Earth’s well-being.

Ninety-nine percent of the $50 million project was financed through the French government and private companies. To get people more involved, Rougerie is crowdfunding the last 1 percent of the project. “The more humans understand about the underwater world, the more respect they will have for it,” he says.

22 People: Number the SeaOrbiter can host. The ship will carry a mix of scientists and crew members.

Quite a View: ‘We want people to appropriate the project to themselves,” says Rougerie. Which is why he raised money through KissKissBankBank, a French crowdsourcing website, to fund construction of the Eye of the SeaOrbiter. Equivalent to a ship’s crow’s nest, the Eye towers 60 feet above the surface. It serves as a lookout and houses a communications system that lets the crew send live broadcasts of life on board.

Hard at Work: Keeping busy won’t be a problem for the crew. The “modular lab” can be used as a laboratory for scientists as well as a fitness room equipped with treadmills. The lab also includes a medical zone. A certified doctor with basic surgery skills will be on board in the event of an emergency.

2,600 Tons Displacement: The overall weight of the ship. It is built from 500 tons of Sealium, a recyclable aluminum designed for marine environments.

A Life Aquatic: Given that voyages will last three to six months, there will be ample time to collect data and perform experiments. The underwater area, known as the hyperbaric lab, is equipped with an observation deck made of transparent polycarbonate panels, allowing for direct underwater observation. Because the conditions underwater are similar to those in space in terms of pressure and isolation, the SeaOrbiter will be used by NASA and ESA (the European equivalent) for protocol training as well as physiological and psychological experiments.

Go With the Flow: The SeaOrbiter was designed primarily to float along with the ocean’s natural currents, allowing scientists to study the relationship between those currents and climate. The keel weighs 180 tons and helps provide stability to the ship. It can be retracted when the vessel is in shallow water.

5 Ships: The total number of SeaOrbiters Rougerie eventually hopes to build, one to sail in each of Earth’s oceans. A number of partners have given their support to the SeaOrbiter project, including National Geographic and UNESCO.

IMAGE: Courtesy Company
From the March 2014 issue of Inc. magazine

Community broadcasting? Where’s the value in that?

Community broadcasting? Where's the value in that?

By Juliet Fox, University of Melbourne

The National Commission of Audit - released on May 1 – recommends slashing all community broadcasting funding in Australia. For some, this is a logical response to the nation’s need to collectively “shoulder the burden” of our apparent economic woes. For others it appears both unexplained and unjustified.

Certainly it raises questions with regard to both the role of media in our society, and the “value” of community broadcasting.

There are more than 360 community radio stations around Australia, each of them, in theory, with an inclusive governance structure producing local media content by and for their local communities. The stations – ethnic, religious, youth, GLBTI, radio for the print handicapped, music, Indigenous, along with more than 80 TV stations – make up Australia’s third media sector, and are powered by more than 20,000 volunteers.

The sector often flies under the radar of the Australia psyche, yet internationally it is consistently held up as one of the world’s most expansive and successful examples of community broadcasting.

In the last budget the sector received A$17.7 million in Federal Government funds – with just over $5 million of that dedicated to the transition to digital radio technology. Yet in three short sentences – in Volume 2 of the Appendix – the Commission of Audit has deemed community broadcasting unworthy of Federal Government funds:

The Commonwealth Government already provides over $1 billion per annum to the operation of the public broadcasters. There is a limited rationale for the Commonwealth to also subsidise community radio services. Continued government funding of this area does not meet the Report’s principles of good governance.

Since 1984 the Community Broadcasting Foundation (originally called the Public Broadcasting Foundation) has transparently distributed public funds to community broadcasters. As an independent non-profit funding body, it allocates grants through competitive rounds assessed by volunteer committees.

David Jackmanson

The grants are small financial contributions that in many instances make the difference between a station covering its basic running and transmission costs, or not. Isn’t this public money well spent?

Community broadcasting began in Australia in the mid 1970s and is different to public broadcasting. It arose out of an identified need to provide an accessible space for ordinary Australians to have a voice. That need has not disappeared.

Despite more than four decades of radical change within media technology and content production, there remains a critical need to actively facilitate the voices, issues and opinions that are underrepresented in the mainstream media.

The Commission of Audit noted that:

Media convergence, especially the availability and access of text, audio and video media via the internet, is increasingly eliminating the traditional arguments for public broadcasting. The need for government intervention or support has now been largely superseded by technology and commercial imperatives.

Where is the evidence to support such a claim? While the internet provides many opportunities, it does not have a democratic intent, or a big picture focus on the role of the media in striving for the betterment of society.

Online media platforms do not seek to address issues of inequality and injustice. Information and access online is not free, and in many parts of the country even getting online remains a challenge.


Neither online technologies, nor public broadcasters, actively facilitate marginalised people having a voice in the media. Community broadcasting does all of these things – which is why its democratic function remains essential.

The recommendation by the Commission of Audit to stop funding community broadcasting goes to the heart of what we value – and what “value” indeed means in our present-day society. It makes us contemplate what is deserving of our public funds. Among the many questions raised are the following:

  • Do we consider independent, local community news and information, along with community language radio shows, and a significant space for local music and culture, to be of value?

  • Do we want to have community owned and operated media outlets?

  • Do we need a third media sector – separate from public and commercial – that prioritises the access and participation of everyday Australians?

  • Are we going to accept that public funding of community broadcasting activities doesn’t equate with “good governance”?

Martin Djablik

The issue of value is deeply ingrained in an ideology that is ubiquitous throughout the Commission of Audit and the Abbott Government. It is a value system that clearly prioritises the economy above community.

There is absolutely no evidence to suggest this model presents increased opportunities for the poor and marginalised to participate in the media. Similarly, there is no evidence that a “free” market economy equates with an egalitarian distribution of freedom of speech.

Consistently the public’s active participation in society is considered vital to a functioning democracy. And the media plays a central role in the flow of information, along with the sharing of views and ideas.

Community broadcasting is in a unique position to contribute to communicative democracy. If there was ever a need to step up and voice your support for a non-commercial, independent community broadcasting sector in Australia it is now. Before the first nail is placed in the community broadcasting coffin.

The Conversation

Juliet Fox is 3CR's Project Coordinator. From 2004-2010 she was a volunteer, elected representative on the grants committee of the Community Broadcasting Foundation and served as Board member and Treasurer (2008-2010).

This article was originally published on The Conversation.
Read the original article.