Existence

"Clocks on GPS satellites run faster than clocks at rest on the earth’s surface. Thus GPS satellite clock frequencies need to be adjusted by a fraction of about -5.3 x 10^-10 relative to the earth’s geoid, to compensate for this effect."Found on pg. 8.Clocks tick faster for the satellites because they are further away from Earth's center of gravity than the clocks on the ground. These clocks are also adjusted by ground command from time to time to make up for these relativistic effects. This is required because the receiver is receiving time signatures from the satellites. The difference in the time signatures is used to calculate how far away the satellite is because the speed of light is constant. If the clocks in the satellites were not adjusted on a regular basis then GPS wouldn't work.

And they have to do so by adjusting the definition of time. These numbers are way off, but they have to redefine an hour as taking 61 minutes instead of 60. This is because time moves more quickly for the satellites compared to an observer on the surface of the Earth. Even with this internal correction the time on the satellites has to be constantly reset by ground control.Edited by Taq, : No reason given.

Then what word should we use for the observed fact that time moves at different rates in different frames of reference? We could use the amount of time it takes for light to travel one meter. The oscillation of cesium has been mentioned before. Pretty much any physical interaction that depends on time would be applicable. For example, the rate at which iron is oxidized by free oxygen could be used. The rate at which a specific pendulum swings.

The experimental results that clearly demonstrate that clocks tick at different rates dependent on their position within a gravitational field. The time it takes for light to travel a meter. Use whatever units you want to. Why don't you look up the units for frequency. Last I checked, frequency is measured in Hz which is cycles/second. Everything depends on time. It is an integral part of the universe. Can you name a single event that does not have a time component? It occurs at a specific rate in a specific environment. Rate is measured in time. Or do you really think that a car will completely lack rust and then be completely rusted in less than a Plank second? The velocity of the pendulum is measured in distance/time. The oscillations of the pendulum are measured in cycles/time. Time exists whether man is there to measure it or not.

Yes and no. If you are in the spaceship with the cesium clock you will record the same number of oscillations per second as you did on Earth.Let's say you synch up two cesium clocks. You devise a way to precisely measure the number of oscillations per second so you will be able to measure any changes in the frequency of the clock. You send one clock up into space along with someone who can measure the oscillations per second. You let the spaceship stay up for a month or so, and then bring it back down to Earth.So what are the observations? The clocks are now out of synch. The clock that went up into space is ahead of the clock that remained on the Earth. When you compare notes on the actual measurements of the oscillations you will find that they were the same from the time the clock was on the Earth, while it was in space, and on the return trip.How do you explain this? [qs]The reduced gravity will make the clock tick faster because of less force exerted upon the atoms.[/quote]False. The oscillations stay the same.

The second, as a unit, is an arbitrarily agreed upon segment of time that can be defined by quite a few phsyical events such as the speed of light, oscillation of a cesium atom, etc. No matter what our units are the speed of light is the same (in a vacuum), as is the rate of oscillations within a cesium atom. Of course. It just so happens that the rate of chemical reactions are consistent so they could, conceivably, be used as a timer if you wanted. The passage of time, no matter the definition as measured by physical interactions, is relative between frames of reference. I defined it in my example with the satellite with the atomic clock.ABE: If you want very precise definitions of time, then here are a couple:One second is the amount of time it takes light to travel 299,792,458 meters in a vacuum. It is also the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. Take your pick, they are both the same amount of time.Edited by Taq, : No reason given.

Then what word should we use to describe the observed fact that objective measurements of time differ between frames of reference where there is a difference in gravity or velocity between frames of reference?Perhaps it would help if we describe what time dilation looks like, and why it got that name. Let's say that you are parked in a space ship near a black hole. Someone gets into an airplane, starts up the propeller, and flies towards the event horizon of the black hole. You watch the airplane from the space ship.Your observations from the space ship:As the airplane approaches the event horizon you notice that the propeller goes slower, and slower, and slower, until it appears to almost stop moving (along with the entire airplane) as it nears the event horizon. The plane never crosses the event horizon in the time you observe it, nor over the next few years.The observations made by the airplane pilot:The pilot notices nothing out of the ordinary. The speed of the propeller never changes, the airplane itself never slows down, and the pilot moves right past the event horizon in short order.So why is there a difference in the observations? Relativity. The passage of time is different between frames of reference. From the spaceship, it appears that time is being stretched so that everything slows down. That is time dilation.If you don't like this description or the use of "dilation" then please come up with a different word to describe these observations. And we showed why his argument is not valid. He's a crackpot. The aging rate is the same. The passage of time is different between the two frames of reference. For the twin in the spaceship not as much time has gone by compared to the twin who stayed on earth.

If this is your position then perhaps you should discuss the science instead of arguing semantics. The GPS satellites have been put forth. They demonstrate relativistic effects quite nicely, and you continue to ignore it.There is also the Hafele-Keating experiment. From the wiki page:

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According to special relativity, the rate of a clock is greatest according to an observer who is at rest with respect to the clock. In a frame of reference in which the clock is not at rest, the clock runs slower, and the effect is proportional to the square of the velocity. In a frame of reference at rest with respect to the center of the earth, the clock aboard the plane moving eastward, in the direction of the Earth's rotation, has a greater velocity (resulting in a relative time loss) than a clock that remains on the ground, while the clock aboard the plane moving westward, against the Earth's rotation, has a lower velocity than the one on the ground, resulting in a relative time gain.

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According to general relativity, another effect comes into play: the slight increase in gravitational potential due to altitude that speeds the clocks back up. Since the aircraft are flying at roughly the same altitude in both directions, this effect is more "constant" between the two clocks, but nevertheless it causes a difference in comparison to the clock on the ground. . .

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The published outcome of the experiment was consistent with special and general relativity. The observed time gains and losses were different from zero to a high degree of confidence, and were in agreement with relativistic predictions to within the ~10% precision of the experiment. The results were verified in an improved experiment in 1976 by the University of Maryland, this time verifying the relativistic predictions to a precision of about 1%.[3][4] A reenactment of the original experiment took place on the 25th anniversary of the original experiment, using more precise atomic clocks, and the results were verified to a higher degree of accuracy.[5] Nowadays such relativistic effects are, for example, routinely incorporated into the calculations used for the Global Positioning System.[6]

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It was meant to illustrate the reasons that "dilation" is used to describe relativity. First off, everyone would see the mallet strike before the sound waves reached them. This is because the propogation of light is faster than the propogation of sound in our atmosphere. This is not time dilation. Also, each of is sitting down in the same arena so we are both in the same inertial frame of reference.How does this relate to the GPS satellite example or the Hafele-Keating experiment? No, it doesn't. I think you are confusing "crack pot" with "verified theories". He is a crackpot because his he keeps pushing false conclusions and bad math on an internet website. The travel time would not be the same for both of you. Your wife would witness a 4 year trip. You would experience a shorter trip due to time dilation. You and your wife would be much closer in age after your trip.ABE: Here is a decent website with a nice chart.C-ship: The Dilation of TimeAt 0.5c, a day to you would be 1.15 days to your wife, the difference being 0.15 days. Multiply that by 4 and by 365, the number of days that you are traveling at 0.5c, and you get 219 days. Your wife would actually age 219 days more than you during the journey. You would actually experience a shorter trip by 219 days than what your wife observed from Earth. If you are exactly 6 months apart, you would arrive back at Earth to find that your wife is now older than you by a few weeks.Edited by Taq, : No reason given.

Your wife will witness a 2 year trip, but using the same clock she is using you will observe a much shorter trip. This difference in the passage of time increases as your velocity increases. If you are travelling at 0.99c a travel distance of one light year will take about 51 days by the clock used by the traveller. This has all been confirmed by the Hafele-Keating experiment that I linked to before. It has nothing to do with the gravitational force on the clock mechanism. Time ticks at different rates in different interial frames. This was confirmed in the Hafele-Keating experiment where both planes flew at the same altitude. The clocks went out of synch based on which direction they flew (east vs. west) compared to the stationary clock on Earth. The plane flying with the rotation of the Earth did not show as much time dilation as the plane flying against the rotation of the Earth. The effect of altitude is removed from this experiment. False. Time itself moves faster.

You left out the Lorentz transform for each inertial frame. It's called relativity. You know, that thing we have been telling you about in this thread. Your clock ticks at a slower rate when you travel at 0.5c compared to your wife's inertial frame. This is because light HAS TO BE the same speed for all inertial frames. This means that our clocks tick at different rates and our rulers change length in order for light to be the same speed for all observers. A constant speed of light is more than a good idea. It is the law.

Evidence please. Please show that the duration of events is the same for all inertial frames.

Your math is wrong because differences in velocities cause a difference in the passage of time by any measure. We have shown you the equations to use in order to include this observed reality in your calculations. So why don't you include it?

We have, multiple times. We have pointed you to the equations that you need to use in order to measure the passage of time in each frame of reference. You refuse to use them. I even gave you a reference to a real world experiment where these equations were used to accurately predict the time dilation on two planes and an Earth based clock. The equations work, and time dilation is a real observation. So why do you continue to leave them out of your equations? Stubborness?

Then your only complaint is that we call it time dilation instead of duration dilation? So let's use this example to explain what is happening with duration dilation. Before the two stop watches go off on separate journeys the coaches sit down and time the same races. They find that they their results match very closely, to within a few microseconds. From this they know that both of the stop watches are working the same. One of these coaches takes a spaceflight with his team. The other coach promises to watch their progress from Earth using the infinitely powerful and accurate telescope spoken of before.When the Earthbound coah takes a peak on the team in the space ship they are travelling at 0.5c. He times a few 100 meter dashes and records them. When the team gets back from their space trip the two coaches sit down and compare numbers. What do they find?To their surprise, the Earthbound coach thinks that the spacers were running slower than they were on Earth. The coach from the space ship vehemently disagrees. They sit down to compare numbers. In each and every case the Earthbound coach recorded times that were 1.15 times slower than the space ship coach recorded. The coach on the space ship would record 10.00 flat while the Earthbound coach would record 11.5 seconds. This is WAY MORE than the discrepancies seen between the stop watches seen on Earth.Since you have already agreed that stop watches are an accurate way to measure duration, then I can only assume that this example meets your criteria for duration dilation.

NoNukes did a fine job of that. You forgot to add in duration dilation for the traveller due to the constant speed of light.