Theory of relativity and time?
397782
If the clock is constantly moving at constant velocity, then you're right, the people on earth will say the plane's clock is going slower, whereas the people on the plane will say the earth's clocks are slow.\n\nHowever, when the plane starts and stops in these experiments, it undergoes an acceleration, which differentiates the two frames. That's why the plane's clock is behind when it's compared to the earth clock. Basically it's because the plane changes which inertial frames it is a part of when it accelerates. Your point is similar to the twin paradox, I suggest you check out my source, that should clear things up, you sound like you have a solid enough background to understand it.
459592
Let's suppose you had a theory which explained that something would take t seconds.  Another theory says that it would take t + x seconds.  You want both theories to be true.  What do you do?  Well, if you are a genius like Einstein you say that time stretched from t to t + x seconds when you went from one theory to the other.\n\nTake another example.  Suppose you are running a race with a stop watch.  At the end of the race your stop watch says you took 60 seconds.  My stop watch says you took 90 seconds.  The logical explanation is that one or both of our clocks are wrong.  But, if you are an Einstein, you say that time was stretched, and your clock moved slow relative to my clock, but is still accurate.
299439
You've confused the statement of the theory. Let two observers be in the same inertial reference frame with two synchronized watches. One observer accelerates in a negligibly small amount of time to some fraction of the speed of light relative to the other observer. The latter observer will be called O1 and the moving observer O2. \nO2 will measure the time in 01's reference frame to be going *slower* than the time in his frame. Likewise, O1 will measure the passage of time in 02's frame to be going *slower* than in 01's frame (the half-life of particles "increases" depending on their speeds). In other words, given two events A and B that always occur t seconds apart in O, they will occur at some separation T > t when measured from O'. The same will occur if O' is switched with O in the sentence above.\nQuestions like this usually come from confusing the relativity of simultaneity. Remember that in relativity, there are no two events that are simultaneous with respect to all inertial frames. \nI recommend you check out the text "Spacetime Physics" by Wheeler et al.
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YES! Time travel is possible. For example, an object traveling at high speeds ages more slowly than a stationary object. This means that if you were to travel into outer space and return, moving close to light speed, you could travel thousands of years into the Earth's future.\n\nNewton's most important contribution to science was his mathematical definition of how motion changes with time. He showed that the force causing apples to fall is the same force that drives planetary motions and produces tides. However, Newton was puzzled by the fact that gravity seemed to operate instantaneously at a distance. He admitted he could only describe it without understanding how it worked. Not until Einstein's general theory of relativity was gravity changed from a "force" to the movement of matter along the shortest space in a curved spacetime. The Sun bends spacetime, and spacetime tells planets how to move. For Newton, both space and time were absolute. Space was a fixed, infinite, unmoving metric against which absolute motions could be measured. Newton also believed the universe was pervaded by a single absolute time that could be symbolized by an imaginary clock off somewhere in space. Einstein changed all this with his relativity theories, and once wrote, "Newton, forgive me."\n\nEinstein's first major contribution to the study of time occurred when he revolutionized physics with his "special theory of relativity" by showing how time changes with motion. Today, scientists do not see problems of time or motion as "absolute" with a single correct answer. Because time is relative to the speed one is traveling at, there can never be a clock at the center of the universe to which everyone can set their watches. Your entire life is the blink of an eye to an alien traveling close to the speed of light. Today, Newtonian mechanics have become a special case within Einstein's theory of relativity. Einstein's relativity will eventually become a subset of a new science more comprehensive in its description of the fabric of our universe. (The word "relativity" derives from the fact that the appearance of the world depends on our state of motion; it is "relative.")\n\nWe are a moment in astronomic time, a transient guest of the Earth. Our wet, wrinkled brains do not allow us to comprehend many mysteries of time and space. Our brains evolved to make us run from saber-toothed cats on the American savanna, to hunt deer, and to efficiently scavenge from the kills of large carnivores. Despite our mental limitations, we have come remarkably far. We have managed to pull back the cosmic curtains a crack to let in the light. Questions raised by physicists, from Newton to Kurt Gödel to Einstein to Stephen Hawking, are among the most profound we can ask.\n\nIs time real? Does it flow in one direction only? Does it have a beginning or an end? What is eternity? None of these questions can be answered to scientists' satisfaction. Yet the mere asking of these questions stretches our minds, and the continual search for answers provides useful insights along the way.
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The basic idea behind space-time comes from Einstein’s General Theory of Relativity, so if you’ll bear with me for a moment… What he proposed was a totally new, geometrical description of space and time that led to a different description of gravity—one that linked space to time and mass to energy in a fundamentally geometrical fashion. In other words, mass(-energy) shapes space(-time) instead of acting like a “force” in the traditional Newtonian sense. This alteration in the fundamental geometry of space-time is often described as the “curvature” or “bending” of space. \n\n(Thus, in Newton’s description of gravity, one would say that all bodies exert an attractive gravitational force on one another; “space” is just the place where it happens. In Einstein’s conception, one would say that all bodies change the underlying geometry of space—and time, too—in a way that causes them to be attracted to one another.)\n\nWhat’s important to note is that, in Einstein’s conception, space and time are linked together in a way that doesn’t allow the two to be considered separately.  So we often talk of space-time being “warped” or “curved” by the presence of mass(-energy). The only we see space-time deformed in the Universe around us is by the presence of a lot of matter—light being bent around the Sun, clocks being affected by Earth’s gravity, that sort of thing.  \n\nThe caveat I feel compelled to add is that curvature or bending really only provides an analogy to what the equations tell us. If you want to imagine the effects of an object on its surrounding space(-time), then you can think of it as changing the shape of space(-time) in its vicinity. The distortion is real—we can measure its effects—but the images that are often presented (of flexible sheets of space-time with bowling balls or marbles rolling around on them) simply present analogous situations.\n\nI guess that’s a lot more than you asked for.  I hope it helps.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
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2006 \n\n With a brilliant idea and equations based on Einstein’s relativity theories, Ronald Mallett from the University of Connecticut has devised an experiment to observe a time traveling neutron in a circulating light beam. While his team still needs funding for the project, Mallett calculates that the possibility of time travel using this method could be verified within a decade.
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Time And Relative Dimension In Space
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The key concept of relativity is 'inertial reference frame'.  For the person in the space ship traveling at the speed of light (how they got going that fast, I don't know), they will watch the hands move on their clock in a normal manner.\n\nNow, imagine that you were outside the space ship as it goes whizzing past you at a relative velocity of C and imagine that you could look into the spaceship and see the clock.  As far as you can tell, the clock has stopped.  Even if you had some sort of imaginary telescope that allowed you to watch the clock over a long period of time as it moves past you, it would appear to you as if time was not passing on the space ship.\n\nSince it would take infinite energy to accelerate the space ship up to the speed of light, it is better to think of this in terms of limits or 'as you approach' the speed of light.
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Relativity comes from that the speed of light is constant (everyone sees light moving at the same speed), and that you can't have both this and everyone experiencing space and time the same way.  \nThis then leads to a link between space and time into something some folks call spacetime.  Now just as you can think of something having momentum through space you can think of something as having momentum through time.  Momentum is a physicsy word for that kind of umph you feel when you are hit by a moving object, an aspect of motion related to both speed and mass (mass is what you would probably think of as weight).  More mass = more momentum, more speed = more momentum.  Hopefully that gets that idea across\nAnyhoo, so the E=m C^2 thing can be thought of the momentum of something that is sitting still in space but moving through time.
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i was gonna suggest my physics book. it dedicates one chapter to relativity and Lorentz transformation equations are there.\nIt's University Physics by Young and Freedman.
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Visit this link for a good explanation:\n\nhttp://en.wikipedia.org/wiki/Theory_of_relativity
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EINSTIEN once said that he can't travel in time but one can SEE THE FUTURE . he said that if such a lense can be made that  it can allow us to see the edge of the EARTH in the prescence of  a   powerful laser the affect shall be like: one endsup seeing himself and in a totaly other situation and thus he proposed a theory on this concept of time travel\n\nbut we have to  just cross the speed of light ....... to have this another theory in action\n         this theory states that one can travel in time when he travels the  7times faster speed of light, and   it is surely going to take a lot of time to prove or disprove this theory ................as EINSTEIN could never prove the previous one!!!!!!!!!!!!!!!!!!!
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Well\nrelativity \n\nPhysical theory, introduced by Albert Einstein, that discards the concept of absolute motion and instead treats only relative motion between two systems or frames of reference. One consequence of the theory is that space and time are no longer viewed as separate, independent entities but rather are seen to form a four-dimensional continuum called space-time. Full comprehension of the mathematical formulation of the theory can be attained only through a study of certain branches of mathematics, e.g., tensor calculus. Both the special and general theories have been established and accepted into the structure of physics. Einstein also sought unsuccessfully for many years to incorporate the theory into a unified field theory valid also for subatomic and electromagnetic phenomena.\n\nEvolution from Classical Theory\n\nThe modern theory is an extension of the simpler Galilean or Newtonian concept of relativity, which holds that the laws of mechanics are the same in one system as in another system in uniform motion relative to it. Thus, it is impossible to detect the motion of a system by measurements made within the system, and such motion can be observed only in relation to other systems in uniform motion. The older concept of relativity assumes that space and time are correctly measured separately and regards them as absolute and independent realities. The system of relativity and mechanics of Galileo and Newton is perfectly self-consistent, but the addition of Maxwell's theory of electricity and magnetism to the system leads to fundamental theoretical difficulties related to the problem of absolute motion.
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space time is theory, it is not an individually absolute\nconcept, it depends on relative motion between\ndifferent objects and distinct observers......\nDifferent observers will have different answers\nfrom their point of reference.....\nWe all exist in space time, yet space & time as a\nwhole are different from the parts which we try\nto understand with our perceptions which can and\ndo show illusions of our mind-set ...\nYou can find this idea of space & time in Einstein's\nSpecial Relativity Theory ........\n\nentanglement falls under Quantum Physics and deals\nwith the phenomenon of spatially distant particles having\ncorrelated properties .......
71991
cool question ! i dont believe in time travle , and thats a good point ! thanks
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Two views on the space and time.\n1.\n There are an independent space and independent time:\nWe notice it on our planet - Earth.\nIt is a fhree - dimensional space.\n2.\nThere is simultaneous union of space and time:\nIt is negative four-dimensional (Minkowski) space.\nHerman Minkowski :\n“ Henceforth, space by itself, and time by itself, \nare doomed to fade away into mere shadows,\n and only a kind of union of the two will preserve an independent reality.”\nQuestion.\nWhat  is the “a kind of union of the two “?\nThe answer.\nIt is Vacuum. T=0K.\n=========================\nhttp://www.socratus.com
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Actually time does NOT move forwards or backwards. Don't confuse "motion related" terminology that we use to describe our perception of time with reality.\n\nSo what is time? It is true that our current theories of physics are time invariant, which is just a fancy way of saying that it doesn't matter if time is "moving" forward or backward (here I am using your terminology to say that it doesn't matter if the process is progressing into the future or is regressing back into the past). However, we know that in the real world, things don't regress back into the past, i.e. broken pieces of objects don't spontaneously come together and fix itself. So this fact tells us that the Universe does have a prefer direction even if our physical theories don't.\n\nBut that still does NOT tell us what is time. It just tells us that there is a prefer direction (this direction is related to Entropy as others have said). Still, you may be right in saying that perhaps everything happens all at the same instant, or a better way to say this is that everything that will happen has already happened (i.e. time doesn't really exist). It may be that it is just our perception, our consciousness that give us the illusion of time moving into the future.\n\nThe most definitive description that I know of time is from Einstein's Theory of General Relativity, which describes space and time together as one entity, and spacetime forms the fabric of reality. It is the stage onto which real events can occur and all of existence is defined. But this fabric is dynamic and interacts with matter and energy (the very stuff which can only exist because of spacetime), meaning that matter and energy can affect spacetime.\n\nThis is quite an amazing fact. We usually think of time as something that just "happens". We don't have any influence on it. But Einstein says NO. We may not have a great impact on it, but there are objects in the Universe that does affect spacetime greatly. An example is a blackhole, which warps spacetime.