# World Lines & (x, y, z, t)

Discussion in 'Physics & Math' started by Dinosaur, May 4, 2014.

1. ### Motor DaddyValued Senior Member

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You lost me. At exactly 10 AM which cog do you see moving? How far does it move or rotate at exactly 10 AM? Did you see it move at 10:28? How about 11:01? When did you see it move?

3. ### Write4UValued Senior Member

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But that does not make hop backward in time, only in space; your timeline is always forward iow, you can never go back to an older spacetime coordination. It no longer exists as it did then.

Regardless which 3 dimensional direction you want to hop, you will always create a chronology of hopping. That chronology can be measured in all 3 dimensions, up, down, sideways, diagonal, straight, curved, but always forward in time. Time is an emergent non-causal account of duration.

5. ### Motor DaddyValued Senior Member

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Very good! Did you interpret what I said to be any different? I was making that very point to Farsight. If you really want to take it to extremes then you'd have issues with Einstein's illusionistic ways.

So you agree that an expanding light sphere in space will not necessarily simultaneously reach all receivers that are equal distance away from the center of the sphere at t=0? How does length contraction and time dilation fit into your scheme of 3 dimensional directions and lengths and times?

7. ### Write4UValued Senior Member

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I understand we are theorizing here but at "t0" we were part of a singularity (no outside observers) and at "t10^-36" the universe was in a state of pure energetic chaos, which slowly cooled and one by one allowed for the formation of particles and their obedience to spacetime laws such as GR and QM.

One might ask if a bunch of photons were released inside the sun, they would all arrive at earth at the same time 8 minutes away. The answer is NO and the time difference might be tens of thousands of years. No one sees the same event exactly the same from their point of observation. Ever.

8. ### Motor DaddyValued Senior Member

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You were born at t=0. Your lifespan (duration) is ticking as we speak. We have a point in time that you were born (t=0) and we are counting until the point in time you die. Then we do a little math and find out the total amount of time (duration) you lived from the point in time you were born (t=0) to the point in time you died (t=83 years).

9. ### Farsight

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And you are right.

As I said some time ago, time is very simple, once you get it. You've got it.

10. ### Farsight

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When I looked at it. When did you see exactly 10AM? When the second-hand of your clock moved past the 12?

LOL!

11. ### Motor DaddyValued Senior Member

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So you looked at it at 10 AM and it was moving? How far did it move at 10 AM?

12. ### Write4UValued Senior Member

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Absolutely. My timeline started at t0, however my time line is imbedded in the universal timeline which had its own t0 moment, but is now 13.6 bilion years old (duration) counting by human earth measurments.

13. ### Motor DaddyValued Senior Member

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And all the times and durations of all the objects that have their own timeline like you do elapse at an absolute 1 second per second. No time dilation involved!

14. ### Farsight

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As far as the second hand on your clock moved when it was exactly pointing to the 12. LOL!

The latest figure is 13.8 billion years. See this. Of course, with time being an emergent property of motion, we could be like some guy in a movie. He says the movie is 13 minutes old when it's been running for 13 minutes, even though before that it sat motionless for 13 hours. Or days. Or years. Et cetera.

15. ### Motor DaddyValued Senior Member

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The second hand is at an exact location at 12:00:00, so that means when YOU open the clock and look at it at 12:00:00, then there is no cogs moving at 12:00:00 like you say they do. So please speak about how the cogs are moving at 12:00:00 like you said they do when you open it up and look at it at 12:00:00??

You're the one that said the cogs move when you look at them, so prove it. How far did they move at 12:00:00??

16. ### Write4UValued Senior Member

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I don't know. I see time also as a limitation of the fastest way reality can become explicated. It takes time to change from one state to another state. Thus perhaps , for you, yes time would move at an absolute rate. This rate may not appear the same relative to someone else, but for them their timerate would also move at an absolute rate.

Relativity has nothing to do with individual objects. Relativity always involves at least two object moving relative to each other. Any time distortions would be found in the measurement of that relationship, IMO.

Any talk about time dilation just means there is a different physical condition which affects the apparent duration of an event. It has nothing to do with time itself. Time is a non-causal result and non-perturbative. IOW You cannot manipulate time itself, you can make certain time predictions but they are always dependent on current physical conditions during the event (experiment).
be it GR or QM.

IMO, the universe has uniform properties, with pockets of concentrated energy where otherwise latent natural laws (potentials) would not be apparent.
E = Mc^2 is a perfect example of a latency which only becomes "expressed in reality" under very specific conditions.

17. ### Motor DaddyValued Senior Member

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My time rate stays the same as every other object's time rate stays the same, at 1 second per second, whether I am accelerating or not. If I start at a zero velocity, and I accelerate at a rate of 9.8 m/s^2, then one second after I started to accelerate I am 4.9 meters from the point in space I started to accelerate, and it is 1 second later, and my velocity is 9.8 m/s. This is not debatable, for anyone, it is a fact!

18. ### Write4UValued Senior Member

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Yes, I agree. I tend to look at it from a little different aspect. I see Time and its peculiarities as resulting from physical change. The fastest possiblw way for something to be able to become reality is at the speed of light "c". This is where reality cannot keep up with change and time stands still for one of the observers and the object becomes infinitely long for the other observer. The trick lies in the translation.
If the event is a function of GR time will result in a GR recording of the event. If the event is a function of QM the time associated will reflect that.

I have a feeleng that most of the arguments lie in the different applications of GR and QM and knowing when/where to apply what.

19. ### lpetrichRegistered Senior Member

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(space is fundamental but time isn't)
Not it isn't. Einstein-thumping is not a very good argument, and what's worse, Einstein agreed with me and not you.
On the contrary, I agree with him on space and time -- time is much like an extra space dimension, part of a space-time continuum. But what would it matter if I disagree with him on something? He's not some inspired prophet of revealed truth. Farsight, your arguments are the sorts of arguments a theologian would make, not a scientist.
From my graduate-school years and from studying the professional literature, mathematics and all. You have mainly been working from sources comparable to the Discovery Channel and New Scientist.

He was trying to explain GR in nontechnical terms, much like the Discovery Channel and New Scientist. What you have been doing with it is quote mining it, like a creationist about evolution.

That's the sort of stupidity one sees from creationists. Like a creationist asking how a bird's wings had evolved from a wingless body. This ignores a rather elementary fact of comparative anatomy: birds' wings are front limbs, so existing front limbs were modified into wings. Farsight, I keep on seeing similar elementary blunders from you.
That's a VERY lame approach to bibliographies. Even very informal ones.

20. ### przyksquishyValued Senior Member

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No you can't. You're limited by the speed of light for starters. In practice (being stuck in a human body) it would take you about a second or so to move a metre, and not without an energy cost. You certainly couldn't just casually hop over to Alpha Centauri and back in time for breakfast tomorrow.

There's a "physics" in "relativistic physics". Viewing time as part of a four-dimensional spacetime does not imply arbitrary freedom of displacement in time, just as you do not have arbitrary freedom of displacement in space. In relativistic mechanics, a worldline is normally continuous (i.e. no discrete jumps, either in space or in time) and constrained to having a velocity less than the speed of light (i.e. gradient limited by 45 degrees on a Minkowski diagram), which means a worldline should not be able to loop around backward in time.

So? Why should that be such a terrible thing?

Why should that be evidence of widespread failure to understand the difference between space and spacetime among physicists? Why should it even be evidence that Wheeler misunderstood it? That quote just looks like a casual remark to me, not necessarily intended to be precise.

Proper time doesn't need to be a fundamental quantity to be used in a useful abstraction. It just needs to be measurable.

Even if I agreed with that, why should that be a good reason? You don't own the word "motion" or English language prepositions such as "in" and "through", and you don't hold a monopoly on how they are allowed to be used.

21. ### btrRegistered Member

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Hello Farsight,

In Geons, Black Holes and Quantum Foam (the 2000 paperback edition) Wheeler says something similar on page 235, only with "spacetime" in place of "space". He is actually quoting from another of his books, A Journey into Gravity and Spacetime, but I don't have access to that right now. The version you gave (with "space") doesn't appear anywhere in Wheeler's writings as far as I can see, but I admit I don't had the time or will to make an exhaustive search. Could you post a link so I may see the quote in its original context?

The reason I ask is this: in my experience it is not uncommon to see "spacetime" referred to as a "four-dimensional space" or simply a "space". This is actually a perfectly correct use of terminology - see [1] for the technical meaning of "space", for example. It may be that some ambiguity could arise when we start talking about spacelike hypersurfaces (which are also "spaces", though 3-dimensional, and correspond closely to the everyday meaning of "space"), but the context and the actual mathematics being presented would be enough to resolve the ambiguity for someone familiar with the subject.

To put it mildly, I would consider it a safe bet that Wheeler is not confused about the distinction between the four-dimensional space we call "spacetime", and the 3-dimensional "spaces" it contains as spacelike hypersurfaces. It is virtually certain to me that either (a) it is a misquote, or (b) the quote is accurate, but in context the meaning of "space" is seen to be "spacetime", rather than something like "spacelike hypersurface". If you could dig up the source for that quote I'm sure we could verify that.

Best regards.

---

References:

[1] en.wikipedia.org/wiki/Space_(mathematics)

(Apparently I need 15 posts or more before I can post links.)

22. ### brucepValued Senior Member

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That's not what Wheeler said. He was a contemporary of Einstein. He knew what the geometry is for GR so I doubt he'd be making comments using Euclidean coordinates. This is what he said: [as I'm sure you're aware of] "Mass tells space-time how to curve, and space-time tells mass how to move." Farsight has an extremely low 'intellectual honesty' quotient.

http://astronomyandspace.blogspot.com/2010/06/quote-john-wheeler.html

Welcome.

Last edited: May 8, 2014

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