[yor_on]

Ahh, then you and Geezer might agree?
Okay.

So what about 'gravity'?

[simplified]

Apples in Geezer's garden  are their quantity, but motion is not quantity of motion. Because the quantity of apples can decrease or increase.  Quantity of motion only increases.
 Here I am wrong,because quantity of  created apples only increase.

[yor_on]

Try another example Sim, I'm not sure what you mean by 'quantity of motion'. Are you imagining the apples containing 'frozen motion'?

So if motion is 'time' and matter is 'motion' in some other state, what is gravity?

[simplified]

Try another example Sim, I'm not sure what you mean by 'quantity of motion'. Are you imagining the apples containing 'frozen motion'?

So if motion is 'time' and matter is 'motion' in some other state, what is gravity?

Quantity of motion is time.Quality of motion is speed.I do not know what is gravity.

[Ron Hughes]

I'll make a prediction. The speed of light slows as the Universe expands and has been slowing since the BB. The less dense (mass per cubic meter) the Universe becomes the faster it's clocks will run hence the slowing of c.

[yor_on]

Let's try a new track.

Assume that SpaceTime is a whole thing, whatever that means. Like some blob of jelly, in that blob we have four properties we can see. Length, width, height, time. Those four are needed everywhere.

Then assume that they have some sort of 'proportion' to each other and that by doing one of them you will affect the other. Like speeding So you speed away.. Now, three of them are interchangeable. Width, length and height are just names for one thing.

Distance.

Then we have 'two' things to look at. Distance and time. Those two combined will give you a position. to get the position you will need all three types of distance of course, but they all represent the same. You don't need 'time' for that, even though it is meaningless introducing a position without involving the arrow i believe you can do so on any surface/dimensions theoretically. But time will get introduced when you move, you can't move without involving 'times arrow counting' durations.

For this we also have to assume that none of those dimensions are special. So when you move you simply change the jelly, pushing three dimensions in one way, and time in another. Does this explain it? I can't say it does. It depends on how you look at the universe of course. Me, I look at it from expending 'energy' and from that view a time dilation, as it actually involves less energy consumed by one of the twins relative the other (Younger than) there has to be some equivalence to the 'energy won' by him, if you like.


But I also look at 'energy'  as something only existing as a relation to what defines it. You will get a 'time dilation' from gravity too, and as the 'gravitational potential' even might be outside the invariant mass in a complicated system, as a guess here I could be at rest relative some system in space, moving uniformly, still having a stronger 'time dilation' than any of those objects of invariant mass.

So where is the 'energy' in that? You might assume that gravity then is a form of 'energy' on its own. Which actually make sense to me

If you assume that infinite gravity equals timelessness then all gravity is a time dilation. But it doesn't take care of speed, not without introducing 'invisible/non existing' things like relative mass/momentum/'energy'.

And all of those need an interaction to be true.
==

There are two ways too look at it. From the conceptual plane you can define infinite gravity as being 'timelessness', watching the object hovering forever as it closes in on that center of gravity. Then there is the viewpoint of the object itself. There, as far as I understands it, times arrow never stops ticking, and what you observe as no motion, equaling 'timelessness' that object will see as both a motion, and durations.

As I said, no motion without durations.

[yor_on]

So what exist without needing relations to be shown? But before we do let's put down some ground-rules. Although everything may interact through radiation there is a simple and definite difference between that, and what we observe as being 'here' in a prolonged manner. And you just have to find those socks, just where you put them last night to confirm that(fat chance of that though:).

Distance? that one is really interesting. Is Lorentz contraction a geometric illusion or is it real. but still, even if Lorentz contraction exist distance will still be needed for matter, how ever contracted it might become. And that should mean that matter and distance have a 'reality', independent of anything else. So matter exist, and 'distance' exist, even though 'plastic', changing according to invariant mass and speed. What more exists independently? Light?

I don't think so myself. Light only exist in its interactions, that we find it to have a speed is not a proof of it existing independently. Remember that I'm speaking from the inside of our jelly discussing the idea of 'independently' here. Meaning that I look at what I could expect to exist inside without needing to be defined by anything else but as seen from the inside. I do have some other ideas about light, but those are not as seen from inside our jello. And I'm jumping between concepts the whole time, but I have a purpose with it, I hope Anyway, speed becomes, as we can see conceptually, only a expression of what frame you are in. Then again, we have one frame where times always tick, the one you exist in, and in that one speed must exist as long as you're made out of matter. But even so it doesn't prove that light has one, as you only can observe it in its interaction. Light quanta is not your socks.

There are two ways here of course. You might want to define it as the only thing being sure is those light quanta, as nothing can exist without them confirming it through their interactions, be it touch, looking, or measuring some other way.
==

So yes, in one way you can define both speed, distance and matter to have a existence 'independently' as they never, not even nearing a infinite gravity will totally disappear. They can't. That I define 'timelessness' as 'infinite gravity' doesn't mean that any of those properties can reach that state, from any frame. Except when compressing, aka a Black Hole that is. But not by speed.

What would happen if the universe suddenly got a infinite gravity? As far as I can see the whole universe would, from a 'outside' observer, contract, maybe under what would be possible to measure for that observer. What would happen for us inside that universe then?

Assume no new 'tidal forces' coming for it, would we all disappear, becoming infinite gravity too, would we get event horizons? If we would then the universe still would need to exist.
==

So what differs a compression from speed? With a speed there will never be a state where you won't be observable from another observer, no matter how near you come to lights speed in a vacuum. With a compression there comes a 'state' in where the universe closes you in behind that event horizon and where we can't know what's happening anymore.

How did it do that?

It eats the radiation. Assume that this universe of infinite gravity exist, eating us. If there is no event horizon(s), where is its center? Assume you were alone in that universe of infinite gravity, no tidal-forces acting on you, would you notice a gravity? For this you might assume that the 'gravity' is equally in all points.

Would it exist to you?

[Geezer]

Assume that SpaceTime is a whole thing, whatever that means. Like some blob of jelly, in that blob we have four properties we can see. Length, width, height, time. Those four are needed everywhere.

Works for me. I'm glad to see you are finally coming round to accepting my atmospheric pressure analogy  [].

BTW - what flavour is the jelly? Personally, I like lime best.

[yor_on]

Ha, just you wait. I'm going to turn it outside in
The jelly should be lime, shouldn't it?

[Geezer]

Careful now. We don't want to accidentally rip the fabric of spacelime, do we?

[yor_on]

Nah, turning the universe outside in should mean that it still is 'whole', just outside in
Maybe )

[yor_on]

There is a definite difference between 'gravity' and anything else I can think of. If we look at SpaceTime as this ah, lime-jelly then that jelly will exist for an 'outside' observer no matter what speed he deems our universe to have. but with a 'infinite gravity' acting on it I expect him to see it disappear.
==

And one more thing. As seen from where we are we exist, and time, speed, distances, light and matter, and space all play a game defining limits for that existence. And the only thing I see crossing that boundary defining SpaceTime is gravity.

Compression is another description, is that the same? Nope, compression is a definition we use for describing matter under pressure. The pressure being gravity in my example. So, could we compress something into a black hole without using gravity? I don't know, but I know that the last state will be gravity alone, taking care of the creation of a Black Hole.
==

I called speed and distance, and matter 'independent' didn't I? I'm not sure of that description, they are independent in that they seem to be able to exist inside the jello without 'disappearing', having a true existence if you like, unlike our concept of 'energy' that I only can see as a expression of relations coming true. On the other hand they all seem to be relational to the jello 'SpaceTime', don't they? But Gravity seems to be able to 'exist' on its own even without a SpaceTime. And then we have 'light'. If I look at light as the traffic police of SpaceTime, setting the speed limit then does that mean that light also show this adaption?

Nope.

In a way light is even weirder than gravity. Where gravity is one thing only, well, as I see it light is two things, or more. Light have only one speed, the same from wherever you look. But it also have this 'frequency' that also is its energy, adapting to all other frames. We also find that light can be something not having any definite boundary at the same time as it express itself as 'light quanta' aka 'photons' begetting the same finite properties as all other 'particles', well, except a 'restmass'  that is.

So if I want to look at particles, how should I do it? How do we do it? We measure by radiation, or by other particles of restmass, right? We take a massless timeless point particle and 'bounce' it, or a particle of restmass. And what we use is either 'kinetic energy' or momentum. You can also point out that we use 'energy' 'frequency' for it, but as I doubt 'energy' as anything else than a relation, well, maybe, to me you can see it several ways? But however I see it light exist, and it have a 'energy' that can differ. So how do we create it? Its energy I mean. We use a relation, something, a laser pumping maybe, A cyclotron using EM. We set the 'energy' by that, and of course by what way we let it interact. But if you look at a particle my way it is the relations that define it.

And light is weird.
==

How did we define a 'time dilation'? By comparing frames, right? How do we compare frames? By radiation. That was the way Einstein realized that there would be a 'time dilation' too as I understands it. By looking at the radiation, and the way it only presented one speed, in, and from, any frame of reference chosen. It didn't matter if you already was traveling at 99.99999~ of 'c'. We on earth would still see the light from you coming at us at 'c' no matter if you were traveling towards us, or from us. And to make sense of that he looked at 'time'. Adapting 'times arrow' as compared between frames of reference made it possible for light to behave this way. But it also meant that 'time' no longer was a isolated entity, for it to adapt as it did he had to assume SpaceTime to be a 'whole experience'. It meant that we no longer could expect 'time' to be one unchanging continuous 'force' sweeping the same through SpaceTime. But there is one catch to it as I see it, to you, or me, or anyone it still is that 'force', if we just stay inside our own 'frame of reference'.

So radiation defines a 'time dilation', but to do it we need to compare frames of reference, or bring back the twin to Earth, as in the twin experiment, to actually see the biological difference created by the speed. Does this mean that any of those twins found their time elongated or compressed? Do you find your time being such? Well, as far as I understand it is both, simultaneously, you just need to choose the right 'frame of reference' to compare yourself against, and you can measure both if you like. Assuming that this is correct, have you now lost your past? Your present? Your future? Did your 'arrow of time' jump out the window as you read me

[briligg]

Plowing through this thread in order to get up to date has been really hard, and i admit to skimming sometimes... I take it the last 3 pages are thought experiments directed at building a model in which an arrow of time objectively exists, as a function of gravity, perhaps. I also take it that the kernel of the vast discord in this thread is objection to the idea that time is an illusion. As physicist like to have at least a provisional answer to questions as huge as 'what is time', even though currently physics is completely unable to answer that question scientifically, I think it is fair enough to call it an illusion. They have plenty of well established, well developed fundamental theory that implies it does not flow. All the formulas dedicated to calculating how it *does* flow in our perceived reality are not concerned with the fundamental nature of the universe, just with how it apparently functions. But 'illusion' is just a fill-in assessment as investigation continues. There is no explanation for the arrow of time, so it has to do. With your thought experiments, you have just tried to flesh in a more mentally comfortable structure, but in order to do that, you have had to engage in a huge amount of speculation. Some people prefer to solve the dilemma in this way, some prefer to use QC's method of sticking to what has been established so far, however uncomfortable and inadequate the resulting conclusions are. Humans are weeny, tiny, insignificant creatures. We will never know what is really going on in the Universe. I believe it is important to remember that, in discussions like these, in order to avoid getting all tensed up about it. After all, if there really are beings out there whose understanding are completely beyond our own (i vote there are, on another question in which nobody can claim to know) they would look at our musing on time and chuckle tolerantly. Or be bored. Or crush us with their cosmic pinkies. Something like that.

That said... i am also tremendously interested in the question. I find it pleasant to think of time as a landscape where past and future always exist, even though we for some reason cannot perceive that. I tend to think there is more than a psychological reason for that, as psychology is much less fundamental to reality than physics (unless you assert there is no such thing as objective reality, which is certainly logically defensible). The model i come up with in order to feel cozy with the idea is that our universe is sort of like a wave moving through the dimension of time, like how if you passed a 2D plane through a 3D object, the figures on the plane would constantly change, but what was visible on it at any moment existed for the entire time, and was not moving at all.

I can't find it, but i remember reading a proposition that the double-slit experiment can be nicely solved if you remove time. The patterns on the screen are due to the fact that the photons (or atoms, or what have you) are connected to the future and the past, so the fact they are measured in the future naturally affects the path they take. Feynman also was comfortable with explaining ramifications of his Feynman diagrams in terms of some particles moving from the future to the past. It comes up in the lectures of his that are available online - http://www.vega.org.uk/video/subseries/8  . The April 2010 issue of Discover reported experiments by Tollaksen and Aharonov showing future measurements affect past measurements. It is available through coverleaf.com, but you have to buy it. I'm going to try to put in an excerpt in my next post.

[yor_on]

Yep, you're right. It's all thought experiments, from us all

So, what defines SpaceTime?

Radiation defines it, everything we do, everything we see communicates through radiation, right? And radiation have a 'speed'. How do we know that radiation have a speed? Well, we use the properties we can see inside SpaceTime, like distance and time. Then we say that everything '¨moves' relative each other and that there is no way we can define anything as being at rest relative each other. That's one way of looking at it but not the only one I think.

We already know that 'gravity' can operate outside SpaceTimes boundary's. That we assume it to communicate is a direct result of our idea of SpaceTime as place where nothing is 'lost', and where the conservation laws have a reality of their own. So, how do a Black Hole 'communicate with SpaceTime? This is my view okay I say it doesn't. The Hawking radiation may set a spin by its pair-particle twins annihilation but that spin isn't read by anyone. the idea of a communication is only meaningful if it gets 'read'. It's not enough with assuming that it 'exist'. If nobody had heard Einstein, would the information exist? Yes, on the conceptual plane it would, but for you, here and now, and your sons? And their daughters? That's number one. Then we come to the idea of how it 'communicates'. Nobody more than me having a problem with how we define that spin? If we define it by a measurement what do we mean by that?

That it only can be when a human look at it that the wave function collapse and a 'final' state of that spin comes to bear? how about a dog? How about a steel plate stopping our particle? How about a 'beam splitter' splitting a photon? How can we guarantee that this didn't set a spin? That we will see a opposite spin is true, but that will be true any which way, won't it?

Then we come to the idea that the universe is 'meaningful'. That is the assumption you make when you define an idea of the Universe that in its 'smallest parts' containing 'information' that also need to be 'conserved' for the universe to 'work'. I agree in that the universe for us is 'meaningful' but I'm not as sure if it is our ideas of meaningfulness that defines it. I look at the Universe as a place where it's our mission to find out what that 'meaningfulness' really is. And I expect the universe to have a different conception than us. We have already changed those ideas of meaningfulness several times through history and I'm sure we will do it again.

So is the definition of what spin that particle twin have 'meaningful' to the universe? In a way maybe? We might expect that in 'n' number of annihilations it should be a fifty percent statistical even distribution. If it isn't then that should tell us something about the 'rules' we play by. So that way it should be 'meaningful'. But do the universe need to set every spin to a preset pattern? I don't expect it to need that.
==

And yes, we're still discussing 'time' and 'time dilations'. And I agree, that's my point of view too. That there is a 'arrow of time'. You might want to define it as process of 'decay' like entropy, but it won't chance the facts. Inside your own 'room time geometry' there will always exist a 'arrow of time'. That one is very easy to see. And without it nothing would be able to be discussed. When it comes to Feynman diagram they rest upon the 'time reversibility' we see on a quantum level. That reversibility is a sign of what 'time' is too, just as time dilation is. But so is the arrow you actually have. One can't just pick two and ignore the third, at least I can't?

So the arrow exist.

[briligg]

Coverleaf won't let me copy and paste from their site, so i have to put in an image:

[briligg]

We already know that 'gravity' can operate outside SpaceTimes boundary's.

How do we know that?

If nobody had heard Einstein, would the information exist? Yes, on the conceptual plane it would

The conceptual plane? As in, an actual plane that actually exists? I know the human mind really can't get away from that way of looking at it... but we aren't proposing it's a 'place', are we?

[briligg]

If i understand correctly, yoron, you discuss 'measurement' and 'meaning' in order to show the inadequacy of the interpretation of the double slit experiment as showing that human interaction affects reality. But if past and future always exist, their is no need to think what people 'measure' affects what is real. The particle/wave behaves according to what its past, *and* its future dictates. What it does is interact with its environment, including the dimension, if you will, of time.

[yor_on]

Well, yes briligg. As I see it there's a lot of stuff we define conceptually. Time dilations, entanglements, how we think it works on a Quantum level etc. And it has a 'reality' too, even though sometimes at a right corner to what we see normally. the 'reality's' clash, don't they If you're a convinced QM you will defend that 'reality' above all others. If you want a reality based on what we see macroscopically you will 'defend' that.

But that you know already, right?
==
As for how a black hole operate 'outside' SpaceTimes 'boundaries'? It depend on what you think information is, don't it But it is also a fact that a 'Black hole' is a 'singularity', closed to SpaceTime. If you want to define it otherwise you need to show me that you can. I would love to see that proof, and yes, it will need more than string theory, like a actual experiment?

[yor_on]

Okay, that one suits me fine. But I need to take up some history first. Let's first look at entanglements. Einstein was the one that with Podolski and Rosen set up that experiment. He did not like the idea of a 'spooky action at a distance'. "The idea is this: set up an interaction such that two particles are go off in opposite directions and do not interact with anything else. Wait until they are far apart, then measure the momentum of one and the position of the other.

Because of conservation of momentum, you can determine the momentum of the particle not measured, so when you measure it's position you know both it's momentum and position. The only way quantum physics could be true is if the particles could communicate faster then the speed of light."

That is the essence of the EPR experiment, not the spin, even though the spin is as described. The Copenhagen interpretation of this, according to Bohr is that before its measurement the particle exists in a superposition of all possible states. " Bohr liked the idea and used it in his Copenhagen interpretation. Remember our experiment with electrons? Each possible route that the electron could take, called a ghost, could be described by a wave function.

As we shall see later, the "damned quantum jumping" insures that there are only a finite, though large, number of possible routes. When no one is watching, the electron take every possible route and therefore interferes with itself. However, when the electron is observed, it is forced to choose one path. Bohr called this the "collapse of the wave function". The probability that a certain path will be chosen when the wave function collapses is, essentially, the square of the path's wave function. Bohr reasoned that nature likes to keep it possibilities open, and therefore follows every possible path. Only when observed is nature forced to choose only one path, so only then is just one path taken."

And the equations Bohr saw supporting him was primary Erwin Schrödinger's wave functions. "Erwin Schrödinger created quantum equations based on wave mathematics, a mathematical system that corresponds to the world we know much more then the matrices. After the initial shock, first Schrödinger himself then others proved that the equations were mathematically equivalent.

Bohr then invited Schrödinger to Copenhagen where they found that Schrödinger's waves were in fact nothing like real waves. For one thing, each particle that was being described as a wave required three dimensions. Even worse, from Schrödinger's point of view, particles still jumped from one quantum state to another; even expressed in terms of waves space was still not continuous. Upon discovering this, Schrödinger remarked to Bohr that "Had I known that we were not going to get rid of this damned quantum jumping, I never would have involved myself in this business."

And then we have the Pauli exclusion principle splitting what it mean to be of 'restmass' (electrons/Fermions) and of no 'restmass' at all, like photons (Bosons)and perhaps the most important of them all? The Uncertainty Principle where Werner Heisenberg in 1925 proposed that it is in fact physically impossible to determine both the position and the momentum of a particle at the same time. "if you determine an object's position with uncertainty x, there must be an uncertainty in momentum, p, such that xp > h/4pi, where h is Planck's constant."

[briligg]

As I see it there's a lot of stuff we define conceptually. Time dilations, entanglements, how we think it works on a Quantum level etc. And it has a 'reality' too, even though sometimes at a right corner to what we see normally. the 'reality's' clash, don't they If you're a convinced QM you will defend that 'reality' above all others.

Maybe that's heaven. []