Back to my DVD analogy.

We aren't writing on a blank DVD. We are in the middle of a pre-recorded DVD.

The whole DVD is already there, but we don't know the end until we get there.

We still have no evidence to base that untestable assumption on.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

That sounds similar to the way I've posted about it, for one. I don't think of time as real, not in the truest sense, anyway. In the first sense, there is only space and matter. No past, no future; only now, the present. There is space and there is matter; the universe, existence. There are no increments of time creeping by, or river of time, or moments.

But then there is motion. Matter moves through space regularly, consistently changing positions and states, and that is where time steps in. My definition of time is a measure of a comparison between two or more motions. For instance, the rotation of the Earth we call a day, or the revolution of the Earth around the sun for a year. Those are really just cyclic regular motions we use to compare everything else. We can do this with any motion that is steady and consistent, as with a clock. So in my way of thinking about it, there is really just space, matter, and motion, always in the now in the primary sense, and time comes secondary to that, but only as a measure, a convenient mathematical tool for comparing motions.

My definition of time coincides with astromark's comments rather well. The way I have defined time above, time itself does not and cannot run faster or slower, for it does not run at all. Only the devices that compare motions, such as clocks, along with everything else that exists within the same frame of reference, can run slower or faster, and so a comparison between two frames of reference is really a comparison of the rate of the motion within each frame to the other.

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To run off on a tangent somewhat, you also mentioned time travel, and this would lie on similar ground. In order to reverse time, one must first somehow reverse all of the motions that have taken place. Some things might not run as well forward as back, though, so some of the physics might also need to be altered. To truly be as they were, we must reverse everything, like a video tape, right down to the last particle and photon. But many of the photons would have already travelled far away from the central zone we wish to reverse, perhaps light years away, depending upon how far back we wish to go, and we would have to find some way to retrieve them and send them all back the same way they came.

So as a fun exercise, let's say we build some kind of containment field around the Earth. Nothing can escape and nothing gets in. We are capable of altering the physics within this field in such a way that motion can be run backward and forward at will. Any particles and photons that reach the boundary of the field will just bounce back in, and when the field is reversed, they will just come back and bounce the other way, the way they came. Everything can be run forward or back, just like in a video tape.

But you see, there is a problem with that as well, because when most people talk about going back in time, they mean going back within their own history with the knowledge they have now. Going back wouldn't do much good if they just go back with the same knowledge they had and do the exact same things over again, not even knowing they had already done the same things before. In order to retain that knowledge, they must leave the containment field, reverse all of the motions from the outside, and come back in. But if they do that, then the essentially part of their life's history is missing, themself. While reversing the motion, they would no longer be present, so everything they affected, everyone they had contact with, and every particle and photon that react with them would now pass through where they ordinarily would have been, and play out in a different way, and things would reverse to an entirely different history than they remembered, mostly depending upon how far back everything is reversed.

Now, if one just went back a little bit like that, they might not change too much of their own history, although anyone they had direct contact with at the point that the reversing stops would be surprised to see them suddenly gone, since that's the last thing they remembered. Also, one could probably go back to the day before, knowing the lottery numbers for the next day, as long as they hadn't had any direct contact with anybody on the lottery commision or anything, or anything that might affect how the numbers turn up.

One couldn't go much further back than when the containment field was built, either. If they did, the history would come out differently than it did before the field was in place also, and since many particles and photons and such would already be lost to the rest of the universe, it would probably just make a big mess the further back they tried to go. I'm wondering also, in order to solve that reversing one's own history without them present thing, if one could leave the containment field, record some important knowledge, and then return to within the field and reverse everything then. Maybe they could make a clone and send that back with the same knowledge to be reversed somehow. Well, anyway, that was fun to think about, but it's beginning to sound like a sci-fi novel, and I'm sure you get the idea, so I'll stop here ...

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Let's put together the pieces of The Grand Puzzle . (website)

"Let's define another operator, Sz, which we won't pay any attention to."
"This transformation will automatically make zero equal zero."
"It may be true that zero equals zero -- and that is certainly an equality -- but I don't want to go into the details at this time."

Ah, Now you've got it!

So, where is a second really a second? Only at one very special place at precisely the right radius from r=0...

Hence the three questions...

and, is a second passing any differently for a person at the center of the Earth than it is for me sitting here typing this?

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Everywhere. A second can never be anything but a second, or you have the wrong definition.

If relativity is correct, and it seems to be, the answer is "no".

I was in a terrible rush that day... as in 'understand,' 'pertinent,', irrelevant' or even rephrase... i admit... that was very messy... i just don't have the time to be as accurate sometimes.

A second for someone walking is slower than for someone sitting still. Too small to notice, but slower nevertheless.

But what if the person who's walking is walking west (thus rotating around the Earth slightly more slowly)?

The second is not slower for the someone walking, and it's not slower for the person standing still. What is slower is the way the standing person conceptualizes a second for the walking person-- the way the standing person matches up mentally the beginning and end of his/her second to the beginning and end of the walker's second. The way to tell this must be true is to note that the walking person thinks it is the standing person's second that matches up to be too long. In the presence of acceleration or gravity, like in the twin paradox, you can make the two come together, and only then will they have to agree on the same "matching up", which will also end up exhibiting less elapsed time for one than the other. But that doesn't mean anyone's "time was slower", it just means you ended up matching up less time to more time between the two.

I can see why the curvature of space-time effects clocks, aging ect. within its area of curvature, but why do clocks slow when in motion or to put it another way, why does the astronaut age less and less as he goes faster and faster (from our viewpoint)?

Think of the space-time interval, which is an invariant across frames. When you are seen to move through space you must be seen to move slower through time to compensate. Or to put it another way, time is maximal in your own rest frame, if you are moving as seen from a different frame, then your time must be seen to be slower than your rest-frame time to maintain the same space-time interval.

As in the two space ship analogy? one above the other sending a beam between each other,from our viewpoint we would have to compensate for the movement across space-time of the beam. That is easier to understand than the actual physical effect it would have (the astronauts driving the space-ships aging less). Could I ask it like this so I understand it better.. From the astrounauts viewpoint there aging does not need to compensate for motion so stays the same, looking at it from our view point, our aging has to take into account the motion of the astronauts across space-time, so we age more?

Close-- I liked how you put it from the astronauts viewpoint, that was true to loglo's correct description of the situation, but when you take our viewpoint I would have said that we have to take into account their moving, so we perceive them as aging less than we perceive our own aging. Remember, the astronaut perceives us as aging less too, not more-- unless you turn his ship around and head back.

The space-time interval is defined (roughly) as
change in spacetime = change in time minus change in space. It is the same when measured from any frame.

As you can see if you if you are at rest then
change in spacetime = change in time

but when you are moving relative to something else then the change in space is subtracted from the change in time ie
your time is seen to run slower when someone on that object looks at your clocks.

Any deeper explanation will have to come from someone who hasn't been working all night.

Yeah - what Ken said

Yes... I hadn't stated from the point of view of the astronaut of us, only the view of themselves and our viewpoint of them.. but I understand what you are saying.

So if I'm looking at this right everything we see, everything is time, its not just that our consciousness perceives a sense of time... if I go outside and look at the night sky.. that is time.. everything is time and we live in it and are connected physically to it. If that is the case? I can understand why space (a word which never made any sense to me, a word without meaning) is a none descriptive word without it's connecton of space-time ?

Hope that didn't sound over the top but i'd never seen it till then

OK.. so you must have 2 observers according to the above. But Carl Sagan said that it was true that atoms decay more slowly the closer they get to the speed of light.

So if I have 2 perfectly synchronized watches, and put one on a ship going 1/10th the speed of light, and wait for it to come back, they should be out of synch. The only observer is me when the other watch gets back.

I had it already, but your description threw me.

You first asked "Clocks run slower at 14,000 ft in the mountains than they do at sea level, Correct?" to which I replied, no they don't.

Then you said "So at 14,000 ft a clock/time is running slower than it is at sea level, and this is a well know concept, and KenG or someone else should have stepped up and explained that this is 'another' time concept as well."

This is still incorrect. A clock runs "faster" at 14,000ft than a clock does at sea level. If you were trying to describe time-dilation as predicted by special relativity, it is only really useful in describing relative motion in empty space. When you mentioned "mountains" or altitudes and the level of the seas, General Relativity was required.

Yes, Special Relativity is required too, but the time dilation caused by the difference in motion at 14,000 ft when compared to sea level is really very small in comparison to the dilation in the other direction caused by the increased distance from the Earth's centre of mass.


As Ken said, a second is always a second, wherever you are. An observer always regards their own seconds as being the correct length. You never find yourself in a place where you look at your clock and think "Hey, it's ticking too fast!" (or too slow).

However, you might observe someone else's clock and perceive it to be running at a faster or slower rate than your own. But of course, they would say the same - that their clock is correct and it is yours that is wrong!

If I hark back once again to the twins paradox, where one twin makes a relativistic journey and ages only half a