[simplified]

People thought   mirage is illusion of water, but  mirage is sky under a corner of refraction  []

[yor_on]

Yeah, it's a truly weird subject. But time dilation is a direct result of 'frames of reference', or if you like, the idea of 'frames of reference' is the answer to 'time dilation'.

And as it exists?

[simplified]

Yeah, it's a truly weird subject. But time dilation is a direct result of 'frames of reference', or if you like, the idea of 'frames of reference' is the answer to 'time dilation'.

And as it exists?

I have no right to answer your question,because I do not recognise imaginary experiments of Einstein. []

[yor_on]

I was not referring to relativity. I was referring to his ideas on time being an illusion.

And I'm not derailing the thread. I'm just asking you to present some evidence to support your claim that time is an illusion. That was an idea that Einstein came up with very late in his career, long after his work on relativity.

yeah, that is relativity - timelessness is part of relativity, a direct solution to General Relativity, hence it is not merely an idea which was kicked around. Understand that and you might get over yourself for a second.

I never seen Einstein saying that the 'arrow' doesn't exist?
Can you show me where he said that?

That he said that there is no 'now' doesn't state that you don't have a 'arrow of time'. He just defined in from a conceptual point of view in where your 'now' and mine 'now' will differ. But the arrow of time is what makes you age, and think.
===

And another thing, saying that time doesn't exist in fact invalidates Einsteins 'SpaceTime'. Notice the combination Space&Time. Einstein saw it as one 'whole thing', indivisible as I've understood it?

Maybe there are some quote from him where he redefine relativity too, that I missed?

[yor_on]

"In 1949, Gödel wrote an essay in which he used Einstein’s relativity theory to point out that we can send a message to the past. Gödel went a step further. Using Einstein’s general theory of relativity, he arrived at a universe whereupon we can physically travel to the past. He stated that “by making a round trip on a rocket ship in a sufficiently wide curve, it is possible in these worlds to travel into any region of the past, present, and future, and back again, exactly as it is possible in other worlds to travel to distant parts of space.”

  In the same book, some pages later in an article entitled “Reply to Criticisms,” Einstein commends politely his colleague’s paper with these words: “Kurt Gödel’s essay constitutes, in my opinion, an important contribution to the general theory of relativity, especially to the analysis of the concept of time.” This often-quoted statement has been used as a reaffirmation by Einstein that, according to physics, time travel is possible. But did Einstein really confirm Gödel’s findings? Not at all. Just the opposite. He immediately wrote: “The problem here involved disturbed me already at the time of the building up of the general theory of relativity, without my having succeeded in clarifying it.”

    How does Einstein clarify the issue? He doesn’t do it within general theory of relativity. He goes outside relativity to thermodynamics and invokes the Second Law, the law of irreversibility of natural processes and the increase of entropy—the inseparable sister of energy. With the aid of a diagram, Einstein shows Gödel that we cannot “telegraph” back to our own past because the flow of time has an arrow and “there exists no free choice for the direction of the arrow.” He makes it clear that he wants to secure “the one-sided (asymmetrical) character of time.” These are strong and unambiguous words. Einstein explains the reason: “What is essential in this is the fact that the sending of a signal is, in the sense of thermodynamics, an irreversible process, a process which is connected with the growth of entropy (whereas, according to our present knowledge, all elementary processes are reversible).” "
===

And from a solely local definition of a 'frame of reference'. Defining and measuring from its 'inside', whatever that may be, we will find 'entropy' work, or as I see it 'times arrow' keeping a constant duration, the arrow unmeasurable as differing, no matter what you do, speeding away or not.

And that's what I call unique 'room time geometries'.

[yor_on]

The problem of 'time' only comes to be when we try to define it as 'unchanging' for a whole universe. We all know from our own reality that we have a 'arrow' splitting reality in a past as well as a 'future' with something we call a 'present' or 'now' defining where we 'are' in a temporal fashion. What you want to call that 'arrow' I don't really care, as long as you agree on it being undifferentiated, as measured from, and in, your own 'frame of reference'.

And then we come to Newtons 'universally unchanging time'. Well, forget it. That one is a illusion, a conceptual expectation, coming from our experiences of being able to correlate our 'arrows' with each other, inside a more or less common 'frame of reference' aka Earth.

That's not the truth. Einstein gave us the way it really worked. But as measured from the 'inside' of one single 'frame' Newtons definition will hold as far as I can see.

So?
==

Maybe it would be worth it defining what one think might be a 'illusion'?

A. If you make a measurement inside your own 'frame of reference' stating some fact, testable for others. Is that a illusion?

B. If you can't find a way/experiment to prove a proposition to be false, does that make that proposal a illusion?

C. If you believe yourself to define a truth conceptually, without being able to test it inside your 'frame of reference', is that an illusion?
==

A. My idea of 'common durations' of 'times arrow' inside your 'frame of reference' is testable, if we use a wristwatch against heartbeats, or any clock as compare to any other time device, keeping durations.

As for B.? The only way to define it as 'false' is from a 'conceptual standpoint' as I know it? Making a general statement that 'time', or a 'now',doesn't exist on that 'conceptual plane'.

As for C.?
Well, that's for those of you that see it as there existing no 'arrow' to decide.
Is C. a illusion?

It's a tangle that one.

[Bill S]

as measured from the 'inside' of one single 'frame' Newtons definition will hold as far as I can see.

Surely, if that were not the case, the "frame" would not be an inertial frame.

[yor_on]

I'm losing you there Bill?
A inertial frame is defined as a uniformly moving one?

Do you mean that in a accelerating frame my heartbeats will differ when compared to my wristwatch? That is, that times arrow, when measured, will express itself differently. If you mean that, do you have a experiment, or a reference to how?
==

If you assume a constantly (uniformly) accelerating frame, then we're talking gravity according to the principle of equivalence. That should then be Earth. And there my statement will hold.

If you assume an non-constant acceleration? I don't see how 'times arrow' can differ if measured inside that frame of reference? To see the difference I understand it as you will have to compare 'frames of reference'. If we take two space ships coasting either can become your 'inertial frame of reference' for the other. If one of them accelerates, constantly or not, you will observe a temporal difference when compared to your 'frame of reference', just as they will assign to you too, as they pass you. But that only is possible in comparisons between 'frames'. From the inside of its 'frame of reference' the accelerating ship will measure the same timely durations as they had when coasting, well, as far as I know?

[yor_on]

You might be thinking of what happens with a photon that get sent out from a light-source in the front of a accelerating ship, wandering to the aft where you receive it. But then you're thinking energy, and not times arrow.

And as I understands it, when it comes to the energy in a constantly accelerating ship, as that is equivalent to the photon falling into a gravity well, it will blue shift to you sitting further down the gravity well. The same goes for a non-constant acceleration.

Associating the changing frequency with timely 'durations'?

If we would use the light waves as a clock, defining 'times arrow' as ten cycles per second. Then measuring the wave inside that accelerating ship finding it to be twenty cycles per second as it now is compressed relative us. We then could assume that a second now was of a longer duration than before. So far I'm with you, assuming that I'm right in my assumptions about what happens with the light here.

This reasoning is slightly wrong, the clock measuring it inside the ship would be as influenced by gravity, being matter waves, as all other waves. For it to work we will have to assume someone still relative the acceleration measuring that light. So now I'm dropping into 'frames of reference' anyway, comparing between them. But it still works I think.

But notice that the 'durations' I'm discussing as 'never changing', those measured inside any 'frame of reference', or 'room time geometry', won't change. They will, to you, be of the exact same 'duration' as always.

Why I think this works is because the photon will 'cycle up' in 'energy' relative you watching it as it 'falls' into that gravity well. And so should you, assuming that matter-waves react to gravity the same as ordinary waves do. And the reason you do have nothing to do with motion, rather your proximity to the gravity well? 

But, and this is a big 'but'. Either it's like i think but then it can't be only the gravity, can it? No, it has to be the whole 'room time geometry' hasn't it? not only gravity but the speed in itself.. Or I'm totally bicycling up the walls


But then consider what happens if you're up very close to light speed, now turning of your engines, not accelerating any more. According to my earlier reasoning the 'gravity well' that our engine created stops to 'exist'. And as we now are uniformly 'coasting' there is nothing differing us from any other uniformly moving object. Inside that ship the light from your light-bulb no longer will show you any other cycles than it would do from any other uniformly moving, or if you like, inertial object. So does this mean that the relativistic phenomena created by my velocity, outside the ship, have disappeared, just because I turned of the engine? The light from suns in front of me no longer blue shifted relative me?

Not as I know. So using the frequency as a proof for a time dilation inside your own frame of reference? I don't know, you got a point though. But then if we want to use that as a 'acid test' a time dilation only can come to be when accelerating, and as soon as you stop accelerating, no matter your velocity, all time dilation should 'stop'? Also it becomes a question of the Lorentz contraction, as that one still should be there, even with the engines of.

If the 'time dilation' only exist in your acceleration, then if we still see a Lorentz contraction outside the ship? Would that be real? Then you have two ways of 'shortening a journey.

A Time dilation & Lorentz contraction when accelerating
A Lorentz contraction only when 'coasting', moving uniformly.

Alternatively no Lorentz contraction at all as soon as you start 'coasting', no matter what velocity you got from your former acceleration.

Or defining only a 'time dilation' as being real.

Pick your choice
==

I'm open for suggestions

[yor_on]

Another interesting point. If that reasoning was true, then the 'aging' one experience inside that ship is a relation to gravity, not speed per se.

I kind'a like that idea actually
==

It fits very nicely with my question what the ultimate rest frame for matter is.
I suggested that it was infalling, into a black hole, if anyone remember.
That means, matter will only be 'at rest' at 'c', aka 'infinite gravity'

And then we have several statements coming together.

'Times arrow' becomes a function of gravity.
And 'speed/velocity' doesn't exist, neither does 'distance' as such.
Only gravity have a reality of its own.

I really need to think about this, it's very weird though
==

But to get back to my first question, would my heartbeats differ as compared to that clock?
Nope, I don't expect them too myself, so the 'even durations' I was thinking of should be the same? Which gives me a headache

[Geezer]

I thought I saw something recently about atomic clocks that are sufficiently stable to demonstrate the effects of gravity on time by comparing the results from two stationalry clocks in different graviational fields. I don't seem to be able to find it again, so maybe I imagined it.

[yor_on]

No, I seen some experiments sensitive enough to feel if you moved a clock down on the floor relative leaving its twin on the table recently on the net too. Probably have them somewhere?

Nevermind
We seen it both at least )

[yor_on]

Using cycles for defining a time dilation becomes weirder still if we consider that we all consist of 'matter waves'. Then the question becomes if the distance to the gravity well will have an importance for the 'time dilation'

I don't think it have myself? what should define it is the gravitational metric/potential and that one will differ slightly with the distance, although how much?

[yor_on]

And that one neatly solves what a 'time dilation' is.

A 'time dilation' if so, should be a result of gravity acting on matter/waves, compressing them locally. But what causes the 'time dilation' is then not the speed, but the gravity? Still, we need the 'speed' to define a 'gravity' to the space-ship.

And then it should only be accelerating that does it, which should make Lorentz contraction, if still existing with engines of, an illusion

Ahhh )

Hmmm.

Or, which seems more reasonable to me, considering muons, leave Lorentz contraction as being just as real as a time dilation. Which then should be noticeable as you would see a different, much stronger 'time dilation' for a accelerating object than for a 'coasting', if so. But both would present a 'time dilation' to you, as the contraction is equivalent to a time dilation.

How about lightening up that ship one second, as measured from Earth, into 99.99999% of light speed? Then turn of the engine? What would that be equivalent to time-dilation wise? Would doing ten seconds at ??.? of light speed give the exact same 'time dilation'.

would I age 'slowest' if I kept a constant acceleration/deceleration as compared to accelerating then coasting decelerating?

I don't know?
But it's a nice idea.

[Geezer]

No, I seen some experiments sensitive enough to feel if you moved a clock down on the floor relative leaving its twin on the table recently on the net too. Probably have them somewhere?

Nevermind
We seen it both at least )

Yes! Thanks, that was it! What's nice about that one is that it's a very simple and static configuration. No aeroplanes or satellites involved, no twins (unless we say the clocks are twins), and no trips around the Universe. The lack of variables minimizes any opportunity for general obfuscation and wavy arm explanations.

If time is an illusion, I wonder how we might explain the results of that experiment?

[yor_on]

Time is a illusion Geezer

Gravity isn't.
If you was the clock.

Times arrow, aka the 'durations' is the same to you on the floor as on the table, but when looked at from another 'frame', like your wife standing beside you, she will see you age 'slower' the closer you come to the gravity source. I changed my discussion above a little, to fit as I was introducing two frames without thinking of it, so it was slightly wrong, but I actually think it works all the same.

So 'times arrow' becomes an expression of gravity, but the 'durations' of them, although seen to be changing from outside your own 'room time geometry' will to you inside it always be the same.

So sweet
And no math..

[yor_on]

Then maybe assigning some sort of weird 'density' to Space isn't that bad an idea?
After all, we see it in 'inertia', don't we?

[Geezer]

Yes, time (spacetime?) is being influenced by gravity, but isn't it time that controls the motion of the "pendulums" in our atomic clocks, as well as every other process in that locality? Just because it doesn't have a constant effect, that does not mean it's an illusion - in that respect it is a bit like air pressure.

Of course, the clocks don't know anything different. How could they? They are measuring time at their locations.

[yor_on]

According to me heh
Time should be gravity. I've felt something similar a long time, but not being able to formulate it. Bills and yours comments gave me the right 'push' to see how I could put it together.

'Speed' exists of course, as well as 'distance', and 'time' too. It's on that conceptual plane speed and distance disappear to give place for gravity, as their common nominator.

I've had so much trouble with understanding frames of reference Geezer
But now it feels as if I have an idea of what they are.
Ahh, maybe )

[Geezer]

Were your arms waving when you said that?  []

Look! I'm waving mine too.