What is confusing about the paradox is that if I see your clock run slower and you see my clock run slower how can one of us age faster than the other? Since the frames of reference appear symmetrical (I am moving in your frame of reference and you are moving in my frame of reference) how do you explain an age difference? So where is the asymmetry? First off, I want to point out that whether acceleration is instantaneous or not doesn’t really matter for the analysis. What is important is who is doing the acceleration and the duration and size of the relative motion. Suppose you go off in a spaceship and I stay back on earth. To make the analysis simple let’s assume you accelerate instantaneously to the speed of light (with respect to me), you stay at that same relative motion for half a year and then instantaneously decelerate so that you are stationary with respect to me, you stay that way for 5 seconds then instantaneously accelerate to the speed of light to travel back towards me. Let’s see what you observe. Since you are travelling at the speed of light you see my clock standing still. The ray of light sent out to you when the second hand om my clock moved (one second after you left) never catches up to you (until you decelerate). Only when you decelerate to stationary (with respect to me) after half a year do you see my clock suddenly start to tick exactly at the same rate that I see it tick. When, after 5 seconds you accelerate and travel back to Earth you see my clock tick at a much faster rate (twice as fast as what I observe to be exact) as you intercept the light rays counting off the seconds on my clock as each of those light rays are travelling shorter and shorter distances to reach you as you head back to Earth. What do I observe when you stop (with respect to me) after half a year? Nothing!! I will still see your clock standing still. In fact, I will see your clock stand still as long as there are light rays are travelling to Earth that you sent while moving away from me. This is the missing asymmetry we needed! When you are half a light year away, it will take half a light year before those rays reach Earth (so in total a year after you left). Only after that half a year (so in total 1 year) will I see your clock suddenly start to tick at a (for me) normal rate. But only for 5 seconds because after half a light year and 5 seconds (after you stopped with respect to me) you will have landed back on Earth! So summarising: you saw my clock stand still for half a year, run at the same rate that I saw my clock run for 5 seconds and then run twice as fast for half a year. Both you and I will have seen my clock measure off 1 year and 5 seconds. I however will only see that your clock has moved forward by 5 seconds when you land. You saw yourself take off, then suddenly see your clock tick for 5 seconds where your ship was a half light year from Earth, then land. Outside those 5 seconds you had no perception of time. Both you and I will have seen that my clock measure off 5 seconds. If you have a problem with the perception of no time passing whatsoever you can replace light speed with 99.99% of light speed or in fact any other percentage you care to use. Then you will see some time pass on your clock outside the 5 seconds (however small). This all sounds like a latency issue. Where does time dilation creep in? The answer is that whether I am moving away from you or towards you at light speed the light rays I send off also move at light speed to you due to the constancy of light supposition. In a Newton world those speeds (and the resulting analysis) would yield different results due to the effect of using a Newton based velocity addition instead of a relativistic velocity addition. This is a bit more speculative but we could explain time dilation as saying when your clock slows you are packing more “physical time” between two clock ticks. Since speed = distance/time and thus distance = speed * time if I can pack more physical time in my time measurement then for any given speed I will have more physical distance. In my view, with Lorentz contraction there is no actual physical distance shortening, it is our metric (the physical length of a meter) that is changed due to a change in time. Meters are defined using time: the distance light travels in 1/299 792 458 of a second second. If I change my duration of a second then clearly the distance measured will change too.

What is confusing about the paradox is that if I see your clock run slower and you see my clock run slower how can one of us age faster than the other? Since the frames of reference appear symmetrical (I am moving in your frame of reference and you are moving in my frame of reference) how do you explain an age difference? So where is the asymmetry? First off, I want to point out that whether acceleration is instantaneous or not doesn’t really matter for the analysis. What is important is who is doing the acceleration and the duration and size of the relative motion. Suppose you go off in a spaceship and I stay back on earth. To make the analysis simple let’s assume you accelerate instantaneously to the speed of light (with respect to me), you stay at that same relative motion for half a year and then instantaneously decelerate so that you are stationary with respect to me, you stay that way for 5 seconds then instantaneously accelerate to the speed of light to travel back towards me. Let’s see what you observe. Since you are travelling at the speed of light you see my clock standing still. The ray of light sent out to you when the second hand om my clock moved (one second after you left) never catches up to you (until you decelerate). Only when you decelerate to stationary (with respect to me) after half a year do you see my clock suddenly start to tick exactly at the same rate that I see it tick. When, after 5 seconds you accelerate and travel back to Earth you see my clock tick at a much faster rate (twice as fast as what I observe to be exact) as you intercept the light rays counting off the seconds on my clock as each of those light rays are travelling shorter and shorter distances to reach you as you head back to Earth. What do I observe when you stop (with respect to me) after half a year? Nothing!! I will still see your clock standing still. In fact, I will see your clock stand still as long as there are light rays are travelling to Earth that you sent while moving away from me. This is the missing asymmetry we needed! When you are half a light year away, it will take half a light year before those rays reach Earth (so in total a year after you left). Only after that half a year (so in total 1 year) will I see your clock suddenly start to tick at a (for me) normal rate. But only for 5 seconds because after half a light year and 5 seconds (after you stopped with respect to me) you will have landed back on Earth! So summarising: you saw my clock stand still for half a year, run at the same rate that I saw my clock run for 5 seconds and then run twice as fast for half a year. Both you and I will have seen my clock measure off 1 year and 5 seconds. I however will only see that your clock has moved forward by 5 seconds when you land. You saw yourself take off, then suddenly see your clock tick for 5 seconds where your ship was a half light year from Earth, then land. Outside those 5 seconds you had no perception of time. Both you and I will have seen that my clock measure off 5 seconds. If you have a problem with the perception of no time passing whatsoever you can replace light speed with 99.99% of light speed or in fact any other percentage you care to use. Then you will see some time pass on your clock outside the 5 seconds (however small). This all sounds like a latency issue. Where does time dilation creep in? The answer is that whether I am moving away from you or towards you at light speed the light rays I send off also move at light speed to you due to the constancy of light supposition. In a Newton world those speeds (and the resulting analysis) would yield different results due to the effect of using a Newton based velocity addition instead of a relativistic velocity addition. This is a bit more speculative but we could explain time dilation as saying when your clock slows you are packing more “physical time” between two clock ticks. Since speed = distance/time and thus distance = speed * time if I can pack more physical time in my time measurement then for any given speed I will have more physical distance. In my view, with Lorentz contraction there is no actual physical distance shortening, it is our metric (the physical length of a meter) that is changed due to a change in time. Meters are defined using time: the distance light travels in 1/299 792 458 of a second second. If I change my duration of a second then clearly the physical distance measured will change too.

Worst case scenarios involve guesstimations when out of Wifi range. Twins of age become of different age due to travelling under spacetime transformations.

I want to be the observer in the ship, I've always wanted to travel through time, but wait, I'm already traveling through time. In fact I've already traveled 63yrs. into the future.

I thought up a variation of the Twin Paradox, which I call “A One-way Trip to Proxima Centauri.” Is it a Real or just a Seeming Paradox? Summary: As Gracie gets very close to Proxima Centauri, a radio message from Earth tells her one thing, but her super-telescope tells her another. Let's start with some numbers, which I got from Professor Greene's lecture: Proxima Centauri is 4.25 light years from Earth. A rocket ship heading there at 80 percent of the Speed of Light would take 5.31 years to get there (according to a clock on Earth). But the rocket ship's clock, upon arrival at Proxima Centauri will claim that only 3.19 years have gone by. Picture Planet Earth near the left side of your page or screen, and picture Proxima Centauri on the right side. Gracie starts her journey in a rocket ship far to the left of Earth (to use scientific terminology) and she has accelerated to a final and constant 80 percent of the speed of light as she passes Earth, heading toward Proxima Centauri on the right. I had Gracie get a running start for a reason -- to avoid the complication of acceleration on the “important” part of her trip. To be clear: she does not accelerate on the part of her trip from Earth to Proxima Centauri, and we are not concerned with any possible return trip. As she passes near Earth, she sends this message to George: “I am setting my Rocket-Clock to Zero.” He sends her a simultaneous message: “I am setting my Earth-Clock to Zero.” Throughout her trip, George looks through his super-telescope and he notices that Gracie’s Rocket-Clock is moving slowly. Why? Because she is traveling at a very high velocity, and Special Relativity says this causes time dilation. However, when Gracie looks back at Earth with her super-telescope, she notices that the Earth-Clock is moving slowly. Why? Because from her inertial Frame of Reference, she is standing still and the Earth is traveling at a very high velocity away from her. After approximately one year and 22 days on Earth (or 1.06 years), George sends this radio message to Gracie: “My Earth-Clock now reads one year and 22 days.” That message takes 4.25 years to get to Proxima Centauri, and arrives there around the same time Gracie arrives there. She does some math – adds 1.06 years (on the Earth-Clock) to 4.25 years (the radio signal’s travel time at the speed of light) and gets 5.31 years. She figures that is how much time has passed on Earth since she and George synchronized their clocks. But now she is confused. She looks in her super-telescope and it tells her that Earth-Clock is NOT reading 1.06 years – it shows considerably less time (possibly .6 years ?). I assume that light reaches her telescope at the same speed as the radio waves reach her radio receiver. Her super-telescope has told her continuously that the Earth-Clock was moving slowly compared to her Rocket-Clock. But the radio message from George tells her that the Earth-Clock did NOT slow down. To me, that is a real paradox, not a seeming paradox. When she receives George’s radio message, she looks at her Rocket-Clock and sees that, because of Special Relativity’s time dilation, only 3.19 years have passed on her clock. HER clock slowed down, not the one on Earth. She re-checks her math: 1.06 + 4.25 = 5.31 years. Gracie sends this message back to Earth: “My Rocket-Clock reads 3.19 years.” George gets that message 4.25 years later. At that time, his Earth-Clock reads 9.56 years (5.31 + 4.25); but when he adds her “3.19” to 4.25, he gets only 7.44 years. It seems to me that only one Frame of Reference is correct: George’s. That’s because Gracie is the one who is really moving. So, what happened to the notion that all inertial Frames of Reference are equal? I think Einstein said something like: "There is no experiment that can be performed to determine whether one is at rest or moving with constant velocity." Isn't the radio message just such an experiment? Or am I, a non-scientist, missing something? Related to that, Professor Greene stated: "The only time that you can claim to be at rest and the rest of the world is moving by you is if you are going at constant velocity, constant speed in a fixed direction." Well, Gracie is going at a constant velocity. I have a question for Gracie: "When you rendezvoused with Proxima Centauri, and you looked at your Rocket-Clock, it told you that only 3.19 years have passed in your space ship. But Proxima Centauri is 4.25 light years from Earth. How do you explain that? If you were standing still, and Proxima Centauri was moving towards you, was it moving at a speed faster than the speed of light? That's a no-no. And, hanging over this whole trip is another nagging question: how could she not know that she is the one who is moving? I mean, really. She's the one in a rocket ship!