Time Travel: Theories, Paradoxes & Possibilities
he were to move only through time and not through space? In the seventh series episode “Hide,” the Doctor does exactly that. Such a construct is not uncommon in the annals of science fiction. are used by science-fiction authors as means of exploring the relationship between time, space, and human existence. Space, Time & Medicine [Larry Dossey] on south-park-episodes.info Recovering the Soul: A Scientific and Spiritual Approach by Larry Dossey Paperback $ . space does not make time change, rather the view from space and your relationship to Healing is something I am interested in and to find a medical doctor to explain . Space and time are to space-time what arms and legs are to humans. In some All answers are provided by Dr. Sten Odenwald (Raytheon STX) for the NASA.
Rudy RuckerThe Sex Sphere When, in youth, I learned what was called "philosophy" … no one ever mentioned to me the question of "meaning. I imagined that logic could be pursued by taking it for granted that symbols were always, so to speak, transparent, and in no way distorted the objects they were supposed to "mean.
Beginning with the question whether the class of all those classes which are not members of themselves is, or is not, a member of itself; continuing with the problem whether the man who says "I am lying" is lying or speaking the truth; passing through the riddle "is the present King of France bald or not bald, or is the law of excluded middle false?
These conclusions are unpleasant to my vanity, but pleasant to my love of philosophical activity: It ought to arouse our suspicions that people who spend enormous efforts on interpreting [ Martin Heidegger 's] work disagree on the fundamental question whether he was an idealist. For the purposes of this discussion, his lack of a resolute commitment to the basic facts is enough.
Suppose you took the notion of Dasein seriously, in the sense that you thought it referred to a real phenomenon in the real world. Your first question would be: How does the brain cause Dasein and how does Dasein exist in the brain?
Or if you thought the brain was not the right explanatory level you would have to say exactly how and where Dasein is located in the space time trajectory of the organism and you would have to locate the right causes, both the micro causes that are causing Dasein and its causal effects on the organic processes of the organism.
There is no escaping the fact that we all live in one space-time continuum, and if Dasein exists it has to be located and causally situated in that continuum. Furthermore, if you took Dasein seriously you would then have to ask how does Dasein fit into the biological evolutionary scheme? Do other primates have it? What is its evolutionary function? But taking these questions seriously is the price of taking Dasein seriously, unless of course you are denying the primordiality of the basic facts.
In Newton's system of mechanics In Einstein's theory time and space are interwoven, and the way in which they are interwoven depends on the observer.
Instead of three plus one we have four dimensions. Willem de Sitter"Relativity and Modern Theories of the Universe," Kosmos It may be helpful to a good understanding of the conception of the physical universe implied by the general theory of relativity, to consider the different definitions of a straight line.
In the old mechanics, there are four of these, viz.: Are they still identical in the theory of relativity? The definitions 1 and 2 define the straight line as a projection on the three-dimensional space x, y, z of a geodesic in the four-dimensional space-time continuum.
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This projection will be a geodesic in three-dimensional space only under very special conditions. In the general case the two projections will differ from each other, and neither of them will be a geodesic.
Also the projection may be a geodesic in one system of coordinates but not in another. The stretched cord is by definition a geodesic in the three-dimensional space.
As a rule, this will not be a geodesic in the four-dimensional continuum. The rotation axis is also by definition a line in three-dimensional space. The definition, however, presupposes the possibility of the rotation of a rigid body, which would be possible only in a homogeneous, isotropic, and statical field, i.
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The definition is thus meaningless in the general theory of relativity. Science at the Edge In string theory one studies strings moving in a fixed classical spacetime. One of the fundamental discoveries of Einstein is that there is no fixed background. The very geometry of space and time is a dynamical system that evolves in time. The experimental observations that energy leaks from binary pulsars in the form of gravitational waves —at the rate predicted by general relativity to the The hypothesis underlying all approaches to the landscape is that there is a cosmological setting in which different regions or epochs of the universe can have different effective laws.
This implies the existence of spacetime regions not directly observable These regions must either be in the past of our big bang, or far enough away from us to be causally unrelated. Lee Smolin, "A perspective on the landscape problem" arXiv Feb 15, The positive energy theorem was for half a century or more an open challenge to relativists. Many attempts were made to prove flat spacetime was stable, but none completely succeeded completely until a majestic tour de force of geometric reasoning of Shoen and Yau.
This was followed two years later by a proof of Wittenwhich was as elegant as it was short.
Lee Smolin"Positive energy in quantum gravity" arXiv Jun 10, Minkowski, building on Einstein's work, had now discovered that the Universe is made of a four-dimensional "spacetime" fabric that is absolute, not relative.
ThorneBlack Holes and Time Warps: Einstein's Outrageous Legacy There are really four dimensions, three which we call the three planes of Space, and a fourth, Time. There is, however, a tendency to draw an unreal distinction between the former three dimensions and the latter, because it happens that our consciousness moves intermittently in one direction along the latter from the beginning to the end of our lives.
Really this is what is meant by the Fourth Dimension, though some people who talk about the Fourth Dimension do not know they mean it. It is only another way of looking at Time. There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it. But some philosophical people have been asking why three dimensions particularly—why not another direction at right angles to the other three?
You know how on a flat surface, which has only two dimensions, we can represent a figure of a Three-Dimensional solid, and similarly they think that by models of three dimensions they could represent one of four—if they could master the perspective of the thing.
WellsThe Time Machine Minkowski calls a spatial point existing at a temporal point a world point. These coordinates are now called 'space-time coordinates'.
The collection of all imaginable value systems or the set of space-time coordinates Minkowski called the world. This is now called the manifold. The manifold is four-dimensional and each of its space-time points represents an event. Friedel Weinert, The Scientist as Philosopher: And now, in our time, there has been unloosed a cataclysm which has swept away space, time, and matter hitherto regarded as the firmest pillars of natural science, but only to make place for a view of things of wider scope, and entailing a deeper vision.
The scene of action of reality is not a three-dimensional Euclidean space but rather a four-dimensional world, in which space and time are linked together indissolubly. However deep the chasm may be that separates the intuitive nature of space from that of time in our experience, nothing of this qualitative difference enters into the objective world which physics endeavors to crystallize out of direct experience. It is a four-dimensional continuum, which is neither "time" nor "space".
Only the consciousness that passes on in one portion of this world experiences the detached piece which comes to meet it and passes behind it as history, that is, as a process that is going forward in time and takes place in space. It is remarkable that the three-dimensional geometry of the statical world that was put into a complete axiomatic system by Euclid has such a translucent character, whereas we have been able to assume command over the four-dimensional geometry only after a prolonged struggle and by referring to an extensive set of physical phenomena and empirical data.
Only now the theory of relativity has succeeded in enabling our knowledge of physical nature to get a full grasp of the fact of motion, of change in the world. Spacetime tells matter how to move; matter tells spacetime how to curve. In the famous mathematician Minkowski made a remarkable discovery concerning the Lorentz formulae. He showed that, although each observer had his own private space and private time, a public concept which is the same for all observers can be formed by combining space and time in a particular way.
If we regard an inverval of time as a kind of 'distance' in the time dimension, we can convert it into a true distance by multiplying it by the velocity of light, c; in other words, with any time interval we can associate a definite spatial interval, namely the distance which light can travel in empty space in that period.
If, according to a particular observer, the difference in time between any two events is T, this associated spatial interval is cT. Then, if R is the space-distance between these two events, Minkowski showed that the difference of the squares of cT and R has the same value for all observers in uniform relative motion. The square root of this quantity is called the space-time interval between the two events. Hence, although time and three-dimensional space depend on the observer, this new concept of space-time is the same for all observers.
An Introduction to Cosmology Space-time is curved in the neighborhood of material masses, but it is not clear whether the presence of matter causes the curvature of space-time or whether this curvature is itself responsible for the existence of matter.Is Gravity An Illusion? - Space Time - PBS Digital Studios
With regard to the Newtonian concept of absolute rotation, Eddington admitted that Einstein's plenum does in fact provide a world-wide inertial frame, with respect to which it can be measured.
Nevertheless, Eddington believed that Einstein attributed to important a role to matter, for in his universe it appears that not only the metrical properties, as in General Relativity, but the very existence of space depends on the existence of matter.
Eddington preferred to regard matter as a manifestation of the 'structure' of space-time. Shortly after Einstein published his original memoir Moreover, in de Sitter's model, space-time is ' hyperbolic '. There is no absolute time, and each observer will perceive a horizon at which time will appear to him to stand still. An artist's impression of a black hole like the one weighed in this work, sitting in the core of a disk galaxy. The black-hole in NGC weighs , times more than our own Sun.
The ship and its crew would be traveling through time," physicist Stephen Hawking wrote in the Daily Mail in Ten years would pass elsewhere. When they got home, everyone on Earth would have aged five years more than they had.
Cosmic strings Another theory for potential time travelers involves something called cosmic strings — narrow tubes of energy stretched across the entire length of the ever-expanding universe. These thin regions, left over from the early cosmos, are predicted to contain huge amounts of mass and therefore could warp the space-time around them. The approach of two such strings parallel to each other would bend space-time so vigorously and in such a particular configuration that might make time travel possible, in theory.
Time machines It is generally understood that traveling forward or back in time would require a device — a time machine — to take you there. Time machine research often involves bending space-time so far that time lines turn back on themselves to form a loop, technically known as a "closed time-like curve.
BBCAmerica To accomplish this, time machines often are thought to need an exotic form of matter with so-called "negative energy density. Such matter could theoretically exist, but if it did, it might be present only in quantities too small for the construction of a time machine. However, time-travel research suggests time machines are possible without exotic matter.
The work begins with a doughnut-shaped hole enveloped within a sphere of normal matter. Inside this doughnut-shaped vacuum, space-time could get bent upon itself using focused gravitational fields to form a closed time-like curve.
To go back in time, a traveler would race around inside the doughnut, going further back into the past with each lap. This theory has a number of obstacles, however. The gravitational fields required to make such a closed time-like curve would have to be very strong, and manipulating them would have to be very precise. A classic example is the grandfather paradox, in which a time traveler goes back and kills his parents or his grandfather — the major plot line in the "Terminator" movies — or otherwise interferes in their relationship — think "Back to the Future" — so that he is never born or his life is forever altered.
If that were to happen, some physicists say, you would be not be born in one parallel universe but still born in another.
Others say that the photons that make up light prefer self-consistency in timelineswhich would interfere with your evil, suicidal plan. Some scientists disagree with the options mentioned above and say time travel is impossible no matter what your method. The faster-than-light one in particular drew derision from American Museum of Natural History astrophysicist Charles Lu. That "simply, mathematically, doesn't work," he said in a past interview with sister site LiveScience. Also, humans may not be able to withstand time travel at all.
Traveling nearly the speed of light would only take a centrifuge, but that would be lethalsaid Jeff Tollaksen, a professor of physics at Chapman University, in Using gravity would also be deadly. To experience time dilation, one could stand on a neutron starbut the forces a person would experience would rip you apart first. Time travel in fiction Two articles by Space.
Some methods used in fiction include: One-way travel to the future: The traveler leaves home, but the people he or she left behind might age or be dead by the time the traveler returns.
In "Interstellar"there are "tesseracts" available in which astronauts can travel because the vessel represents time as a dimension of space. A similar concept is expressed in Madeleine L'Engle's "A Wrinkle In Time"based on the book series that started inwhere time is folded by means of a tesseract. The book, however, uses supernatural beings to make the travel possible.
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Travelling the space-time vortex: Time travelling while standing still: In "Primer"a traveler stays in a box while time traveling. For each minute they want to go back in time, they need to stay in the box for a minute. If they want to go back a day in time, they have to stay there for 24 hours. Traveling faster than light: The Movie"Superman flies faster than light to go back in time and rescue Lois Lane before she is killed. The concept was also used in the novel "Timescape" by Gregory Benford, in which the protagonist sends hypothetical faster-than-light tachyon particles back to Earth in to warn of disaster.