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scuddyx

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About scuddyx

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  1. Thanks for the link in your post. Like most twin paradox explanations it says the spaceship carrying one twin experiences forces as it turns around and finishes with the question "what role does the acceleration play in this?" The twin paradox can be explained without resorting to acceleration by merely by showing there is simply a change in inertial frame. No forces (GR) are required. SR is sufficient. The twin paradox is extremely useful as it shows that there is no absolute time reference, each inertial frame has its own independent time and that there is no contradiction that two inertial frames observe the time in the other moving more slowly.
  2. The 'deflected' path is actually a geodesic as described by general relativity and is by definition a 'straight line' or shortest path in 'curved spacetime'. Physicists skilled in general relativity may be able to visualise curved spacetime, stress-energy tensors and Riemannian space. But if you accept that gravity causes time dilation - it follows that objects 'simply' take the shortest path (for whatever reason) by travelling close to massive objects. Gravity may eventually be shown (consistent with Einstein's GR) to be an emergent phenomenon from the nature of time itself. Admittedly this is a working hypothesis and, as yet, I don't have supporting maths. 😉
  3. The first observation of light deflection was performed by Arthur Eddington, during the 1919 total solar eclipse, when stars near the Sun were observed to change position. Starlight took a shorter path thanks to gravitational time dilation caused by the Sun.
  4. I think the concept of spacetime makes the understanding of GR unnecessarily difficult. Closer you are to a massive object time slows down. Anything passing through space where time has slows down (to external observers) must also appear to experience travel shorter distances to ensure the speed of light is constant. If something wants to take the shortest path (why it would want do so is another issue) it would travel close to the massive object.
  5. The clocks in every inertial frame of reference run independently of the clocks in every other inertial frame of reference. In addition, there is no absolute time reference that each inertial frame can be compared to. Yes SR is capable of handling accelerating frames. The point I am making is that the twin paradox can be explained without resorting to acceleration. Many twin paradox explanations just end by saying the spaceship carrying one twin experiences forces as it turns around - leaving the novice thinking the forces somehow corrupt the mechanical workings of the clocks. The twin paradox gives profound insights into the nature of time. Special relativity asserts that the speed of light is the same in all inertial frames. The Lorentz transformations are a set of equations that relate the space and time coordinates between inertial frames.
  6. The Twin Paradox doesn’t explain what Time IS – but tells us a few things about it: 1. There is no absolute time reference – each inertial frame has its own independent Time 2. There is no contradiction that two inertial frames observe the time in the other moving more slowly 3. Einstein was wrong. The Twin Paradox can be explained without invoking accelerations
  7. I am trying to explain the twin paradox without acceleration. In my example all the spaceships are moving at constant speed. No startup accelerations, decelerations or turning around. The clock synchronisation is done instantaneously as they pass very close to each other. Is there still an acceleration I am missing? My explanation emphasises the fact that there is no absolute time reference. Many twin paradox explanations flippantly claim its all about the spaceship turning around. Hi Mordred. Thanks for your comments. Do you agree with my reply to swansont?
  8. Is this explanation ok that avoids using forces? Thanks Rather than twin flying it is best to consider synchronised clocks. This avoids talking about acceleration at certain times is the flight. Special relativity doesn’t require an understanding of acceleration – this is dealt with in general relativity. It is not necessary for an actual twin to follow the out and back path or to experience an acceleration at the turning point. Outgoing and incoming spaceships could simply exchange clock readings or videos when they pass each other. Clock A stays on earth and is synchronised to clock B on a spaceship flying past (3/5c). After 5 earth years the spaceship will be at 3 light years and synchronises the clock C on a spaceship flying in the opposite direction. This clock will arrive back at earth after another 5 earth years. The moving clock will only show that a total of 8 years has elapsed. As the twins move apart both will see the other age slower by the same amount (4/5). This is after the time has been corrected for the video to travel between them. When the clocks are synchronised at the turning point there is a change in the frame of reference. For the spaceships to continue watching each other (videos and heart pings) the clocks need to be resynchronised. As they pass by the outbound rocket twin will relay the total number of pings counted so far to the inbound rocket and then the inbound rocket will continue counting all the way to Earth. Outbound rocket twin will be getting low frequency pings and the inbound rocket will be getting high frequency pings. The pings represent the heartbeats so the number of heartbeats by Earth twin will be greater and therefore Earth twin will be older. On the inward journey, there is a new meaning of simultaneity. There is a new clock synchronisation. Remember there is no background absolute time. The synchronisation of clocks must include the time for the clock reading to travel between them at the speed of light. The outgoing spaceship (B) receives pings from the clock left on Earth (A) and from the clock on returning spaceship (C). Clock C will be slow due to time dilation so that when it arrives at Earth it will show a total of 8 years has elapsed whereas the clock left on Earth will show 10 years has elapsed. This is consistent with the twin paradox. Note that clocks A and B will continue to run slow when compared to each other. This is consistent with special relativity as there is no absolute time reference.
  9. "Why does it move at all?" Is this a question that General Relativity answers or one waiting for an answer? Thanks for your replies.
  10. Thanks for replying to my posts. Professor Jim Al-Khalili (theoretical physicist) at the end of his BBC programme “The Amazing World of Gravity” says: Why does the apple fall? Hundreds of years of Scientific inquiry investigating this single action have led us to completely redefine the way we think about the very nature of space and time. And now I’ve been presented with this extraordinary proposition that somehow, in some profound way, the apple falls because it's seeking out the place where Time runs the slowest.
  11. If time runs slower closer you are to a massive object - is it not correct to say matter will move in the direction of decreasing time? This is easier to understand than saying 'spacetime' is curved.
  12. I find it hard to understand General Relativity when it is casually referred to as curvature in spacetime or as the sagging in a trampoline mat. Would a better explanation for the novice be to say things fall because they are seeking out the place where time runs the slowest? For instance, when explaining how light is deflected as it passes close to a star imagine it surrounded by voxels (3D blocks of space). Time runs slowest in the voxels close to the star. Because the speed of light is constant in all frames of reference and as speed = distance /time the voxels close to the star would appear to be smaller to the photons of light. Consequently the quickest route for the path of light would be to travel close the the star. This neatly explains the deflection. Do you agree? Does gravity dictate the flow of time or does time itself define gravity? Thanks
  13. Are you saying the wave function (ψ) is just a number (a vector in Hilbert Space?) and a quantum mechanical operator is required to convert it into a physical quantity? For instance, the expectation value of momentum <p> = ψ*p^ ψ Where p^ = ih(bar)d/dx Thanks
  14. Thanks Studiot. I will try to understand and get back to you.
  15. Closing this thread may be ScienceForums' Greatest Blunder 😉
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