Questions about Space, Time, Motion, Blackholes and Stuff

Discussions on the nature of being, existence, reality and knowledge. What is? How do we know?

Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 16th, 2017, 4:31 am 

BurtJordaan » April 16th, 2017, 3:41 am wrote:Going back to Newton's concept of time, as you suggested earlier, takes us some distance back towards the 'dark ages' - many observations become unexplainable using Newton's concept of time.

With respect Burt, the dark ages were exemplified by the trial of Galileo where the keepers of the current ideology came down hard on any questioning of the then current orthodox ideology. You are mistaken that I am advocating going back to Newton's concept of time, but seem to be utterly incensed that I asked a question about the fundamental assumptions of the current ideology.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby mitchellmckain on April 16th, 2017, 4:25 pm 

rajnz00 » April 16th, 2017, 3:31 am wrote:
BurtJordaan » April 16th, 2017, 3:41 am wrote:Going back to Newton's concept of time, as you suggested earlier, takes us some distance back towards the 'dark ages' - many observations become unexplainable using Newton's concept of time.

With respect Burt, the dark ages were exemplified by the trial of Galileo where the keepers of the current ideology came down hard on any questioning of the then current orthodox ideology. You are mistaken that I am advocating going back to Newton's concept of time, but seem to be utterly incensed that I asked a question about the fundamental assumptions of the current ideology.


Modern science is not an ideology because it is founded on testing things with objective evidence rather than using rhetoric to push what you want. What it looks like you are doing is replacing science with ideology because you are simply deciding what must be the case and looking for a way to prove it. That is not how science does things. Science performs experiments to answer questions and not push desired answers.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 16th, 2017, 4:58 pm 

Modern science is not an ideology because...
Dont try and lecture me what science is about. It sounds like an ideology through some people who try and act like they are high priests of a belief.
Science performs experiments to answer questions and not push desired answers.
Again you haven't a clue what science is about. I didn't hear any questions from you only very emphatic answers, some of which have been wrong.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby mitchellmckain on April 16th, 2017, 8:08 pm 

rajnz00 » April 16th, 2017, 3:58 pm wrote:
Science performs experiments to answer questions and not push desired answers.
Again you haven't a clue what science is about. I didn't hear any questions from you only very emphatic answers, some of which have been wrong.

LOL What? You think anything people do in an internet forum is science? LOL Anybody who imagines such a thing is completely deluded. Science is something have I done and that is why I know the difference from all the other things I do. Science is an activity, NOT a way of life or an ideology. So when Dawkins writes "The God Delusion" or Hawkings write "The Grand Design", I know very well that none of this is science. It is just rhetoric and opinion on religious and philosophical subjects, by people who happen to have done some science.

Science is NOT simply asking questions. Any two year old can do that. Sure asking questions is important. Being willing to listen and test the answers given with something other than bull-headed rhetoric is even more important. But some elaboration is a good idea at this point. For what I speak of here is the work of science. There is also the facts of science and these are the theoretical tools used over and over in the work of science. Examples of such tools include the theory of evolution, General and Special Relativity, and Quantum Field Theory. So to be a scientist, first you master the tools and then you participate in the work. I have done this, have you?

But of course, one of the things people also do is education in science -- helping students to master these tools and that is also something which I did for many years. It is something that can be done to some small degree on internet forums by those who interested. But that is usually not the main reason people participate in internet forums. Science is hardly my only interest, even if informs some of my other interests. So yeah, this is a philosophy venue and I like to talk philosophy. And when we talk philosophy about science then it is only natural for me to bring my experience in science to bear on the subject.

rajnz00 » April 16th, 2017, 3:58 pm wrote:Dont try and lecture me what science is about. It sounds like an ideology through some people who try and act like they are high priests of a belief.

I agree that people do indeed do this. This is why I have said science is not about belief. However, when it comes to the facts of science (i.e. the tools of science) then it is about what works. The good thing about this forum is that it has two sections, so we can keep the philosophy out of the science section and stick to the facts of science there.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 16th, 2017, 10:00 pm 

mitchellmckain wrote:What? You think anything people do in an internet forum is science?

I prefer to take my definitions of science from people who might me a little wiser than you, and I'm not singling you out alone, but others who maybe similarly deluded (as to their own wisdom).

Science is both a body of knowledge, ("facts" as you call them), and a process.
One definition defines Science as "a way of investigating, understanding, and explaining our natural, physical world and the wider universe."

So yes, in so far as it involves investigating, (not necessarily in CERN or Los Alamos, which few have access to), understanding, and explaining our natural, physical world, science can be done on the internet.
Science is NOT simply asking questions. Any two year old can do that.
When he or she does, they engage in one of the processes of science, which is not exclusively your domain, or that of other wise men on here, but belongs to everyone with an inquiring mind.
For what I speak of here is the work of science....So to be a scientist, first you master the tools and then you participate in the work. I have done this, have you?
I believe I have in a modest way. I am an engineer. But first elaborate what you mean by "the work of science", then only can we see what "work of science" we have done.

Here is a definition of science I particularly like, it's by Richard Feynman, Nobel Prize winner, who some consider as the successor of Einstein:

"Science alone of all the subjects contains within itself the lesson of the danger of belief in the infallibility of the greatest teachers in the preceding generation . . .As a matter of fact, I can also define science another way: Science is the belief in the ignorance of experts."

If the greatest teachers of science need to be modest, how much more so, those who are not as great, but believe themselves to be?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 17th, 2017, 1:19 am 

rajnz00 » 16 Apr 2017, 10:31 wrote:With respect Burt, the dark ages were exemplified by the trial of Galileo where the keepers of the current ideology came down hard on any questioning of the then current orthodox ideology. You are mistaken that I am advocating going back to Newton's concept of time, but seem to be utterly incensed that I asked a question about the fundamental assumptions of the current ideology.

My apologies, I agree that you did not advocate that absurdity! I was working on two threads around the same time, with the other poster wanting a return to Newton's absolute time... ;(

Since you did nor comment on the rest of my post, can I assume that you are happy with the core of my reply? I am more than willing to answer well formulated questions on the funadamentals, like I see from you ;)
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 17th, 2017, 1:27 am 

Hi Burt, Not a problem :)
re: the rest of your reply, yes I do have some questions, which I will put to you a little later when I have time.
Regards
Raj
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 17th, 2017, 1:52 am 

I might as well ask the questions now:
BurtJordaan on April 16th, 2017, 3:41 am wrote: The only sense in which spacetime 'moves' is when we consider two reference frames that move relative to each other,
How then is the expansion of the Universe accommodated in spacetime? The so-called "Metric expansion of space" how does it fit into spacetime?

Also some people argue that time is being created also along with space and some say independently of space.
BurtJordaan on April 16th, 2017, 3:41 am wrote: Worldlines are not static, but are traced out by objects moving through 4-D spacetime. So it leaves a trace in its past, but its future is indeterminate.....To make sense out of the world, we need to choose a sensible dimension of the 4-D to represent time, but the structure of the 4-D spacetime does not really care whether we can make sense out of it or not.


What precisely do you mean by “a sensible dimension”? What according to you is time? Why do we need to choose a dimension for it? How do objects move through spacetime? Why do objects only move from the past into the future?

mitchellmckain - SR and GR are perfectly causal and deterministic.

From what I have read I think he is right, so how do say the future is indeterminate?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 17th, 2017, 5:33 am 

rajnz00 » 17 Apr 2017, 07:52 wrote:How then is the expansion of the Universe accommodated in spacetime? The so-called "Metric expansion of space" how does it fit into spacetime?

Distant cosmological objects are all in different inertial frames (spacetimes) than us. And their spacetimes 'move' relative to ours. In an expanding space, the spacetime is negatively curved, even if that space is perfectly flat. This means the distance of objects static in each spacetime are increasing from us (i.e. metric expansion).

What precisely do you mean by “a sensible dimension”? What according to you is time?

When we look around in space, we see events happening - let's take Einstein's famous lightning strikes. Say they leave marks on a flat piece of Earth, so that we can take a meter stick and measure exactly where they have happened in our 3-D coordinate system.

If we have also recorded the arrival time of the light from the strikes on our clock, we can work back and see exactly when, in our time, the strikes must have happened. We can then tell the order in which they have happened. This is how I sensibly decide which is the time dimension of my 4-D spacetime.

How do objects move through spacetime? Why do objects only move from the past into the future?

If I observe a great number of objects, I find that at any time on my clock, some objects get closer to me and some go farther away, but I observe my time to go only forward. This is how I know the objects move through spacetime (in any spatial dimension), but only forward in the time dimension. Why only forward for time, I have no concrete ideas. ;)

I will answer your question about "determinate vs. indeterminate" later, because it goes a little beyond SR and GR.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 17th, 2017, 6:08 am 

rajnz00 » 17 Apr 2017, 07:52 wrote:
mitchellmckain - SR and GR are perfectly causal and deterministic.

From what I have read I think he is right, so how do [you] say the future is indeterminate?

While it is true for pure SR and GR, we also know that they do not convey the complete picture. For SR, quantum dynamics has developed into Quantum Field Theory (QFT), which includes SR, as Mitchell has already mentioned. For GR, that feat has not been achieved.

But anyway, for worldlines in QFT/SR, we can say that the past wordlline is fully determined, but the future worldline is essentially probabilistic. Given the information we have that determines the future worldline of some object in SR, in QFT it is only a probabilistic determination.

Since this is in the epistemology department, one may perhaps argue that even in pure SR (without quantum effects), there may be some future event (say a lightning strike) that we cannot know about at present, but which may influence the future wordline of an object. Does this pass as an indeterminate future worldline?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 17th, 2017, 12:56 pm 

BurtJordaan on April 16th, 2017, 3:41 am wrote: Objects or effects move through spacetime. The only sense in which spacetime 'moves' is when we consider two reference frames that move relative to each other, with the operative word the unified 'spacetime', not 'space and time'.

BurtJordaan on April 17th, 2017, 5:33 am wrote: Distant cosmological objects are all in different inertial frames (spacetimes) than us. And their spacetimes 'move' relative to ours. In an expanding space, the spacetime is negatively curved, even if that space is perfectly flat. This means the distance of objects static in each spacetime are increasing from us (i.e. metric expansion).

Can objects remain static in spacetime? How? Distance increasing from us? Over what? Time? Why are you referring to space and time separately here when you caution against using them separately earlier. You seem to be contradicting yourself.
BurtJordaan on April 17th, 2017, 5:33 am wrote: … let's take Einstein's famous lightning strikes [Never heard of it]. Say they leave marks on a flat piece of Earth, so that we can take a meter stick and measure exactly where they have happened in our 3-D coordinate system.
If we have also recorded the arrival time of the light from the strikes on our clock, we can work back and see exactly when, in our time, the strikes must have happened. We can then tell the order in which they have happened. This is how I sensibly decide which is the time dimension of my 4-D spacetime.

Let the strikes, at points A and B, be 10 Km apart.
Therefore xab = 10 Km
Synchronised clock at A records time of strike at 1 sec
Synchronised clock at B records time of strike at 1.00001 sec
Therefore cTab = 0.00001 sec
Time it would have taken light to travel from A to B = 0.00003333 sec

How can we tell the order in which they happened?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 17th, 2017, 4:22 pm 

rajnz00 » 17 Apr 2017, 18:56 wrote:Can objects remain static in spacetime? How? Distance increasing from us? Over what? Time? Why are you referring to space and time separately here when you caution against using them separately earlier. You seem to be contradicting yourself.

Sorry, poor word choice - I should have said "static in each reference frame". This is usually taken as meaning an object's x,y,z coordinates remain the same in some reference frame, but obviously its time coordinate is changing. There is nothing that can be "static in spacetime". When we have to translate the math to physical descriptions, the splitting of space and time is unavoidable.

I just wanted to correct the above, but I will return to your temporal order question when time allows.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 17th, 2017, 6:21 pm 

BurtJordaan wrote:Sorry, poor word choice - I should have said "static in each reference frame". This is usually taken as meaning an object's x,y,z coordinates remain the same in some reference frame, but obviously its time coordinate is changing.

“Inertial frames” are not real, objects are. They are as fictitious as lines of longitude and latitude. An inertial frame can only be defined by an object or a group of objects linked together, not the other way around. We cannot have an arbitrary x,y,z, coordinate in space, defining placement of objects, without going back to Newton's concept of absolute space.

So your earlier statement, on April 17th, 2017, 5:33 am: "Distant cosmological objects are all in different inertial frames (spacetimes) than us.", placing objects in spacetime rather than in an arbitrary inertial frame, to me, is not a poor choice of words, but rather, true. And because it is true, the objects are not at rest, either temporally or spatially, because of the expansion of space. But if that be true, then I think, the movement of spacetime is also true.

BurtJordaan on April 17th, 2017, 5:33 am wrote: When we have to translate the math to physical descriptions, the splitting of space and time is unavoidable.

Again, to my mind, maths is only true when it describes something about nature. When it doesn’t, I think we should question the maths, rather than question our experience of nature.

The “obviousness” of time changing only comes from our experience of the flow of time. This is not “obvious” from the maths of GR.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 18th, 2017, 12:49 am 

rajnz00 » 18 Apr 2017, 00:21 wrote:“Inertial frames” are not real, objects are. They are as fictitious as lines of longitude and latitude. An inertial frame can only be defined by an object or a group of objects linked together, not the other way around. We cannot have an arbitrary x,y,z, coordinate in space, defining placement of objects, without going back to Newton's concept of absolute space.

Not quite. Although mental constructs, a Minkowski inertial frame is defined by a non-rotating, non-accelerated, non-expanding lattice of fictitious standard rods and synchronized clocks, somewhere in empty space. Observers can be either stationary in such a frame, or be moving relative to it. And such inertial frames can be in motion relative to each others. In cosmology, we normally set such inertial frames to be co-moving with the Hubble flow, meaning any observer static such a frame, will observe an isotropic cosmic background radiation (CMB), with the same average temperature in all directions.

So your earlier statement, on April 17th, 2017, 5:33 am: "Distant cosmological objects are all in different inertial frames (spacetimes) than us.", placing objects in spacetime rather than in an arbitrary inertial frame, to me, is not a poor choice of words, but rather, true.

Yes, this true, but my correction was for the sentence "This means the distance of objects static in each spacetime are increasing from us (i.e. metric expansion)." I corrected that to: This means the distance of objects static in each reference frame are increasing from us (i.e. metric expansion).

Again, to my mind, maths is only true when it describes something about nature. When it doesn’t, I think we should question the maths, rather than question our experience of nature. The “obviousness” of time changing only comes from our experience of the flow of time. This is not “obvious” from the maths of GR.


The math of GR can be formulated with a pre-choice of a time axis as part of its 4-D, or without that pre-choice being made. It makes no difference to the outcome. To a trained GR-specialist, it is perfectly clear how to get the time coordinate out of the Einstein field equations during the process of solving them. In the cosmological solution, a time coordinate falls out in a pretty obvious fashion.

I'll go your temporal order questions in the next reply.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 18th, 2017, 1:43 am 

rajnz00 » 17 Apr 2017, 18:56 wrote:
BurtJordaan on April 17th, 2017, 5:33 am wrote: … let's take Einstein's famous lightning strikes [Never heard of it].

Strange, it is more than 100 years old and still repeated today as a good introduction to the relativity of simultaneity. Here's a short, modern Youtube video: https://www.youtube.com/watch?v=wteiuxyqtoM

Let the strikes, at points A and B, be 10 Km apart.
Therefore xab = 10 Km

But where is the observer? Simultaneity is always relative to some inertial frame with an observer stationary in it. For less clutter, let's choose nanoseconds (ns) and ft as units, because light propagates at very close to 1 ft per ns.

So let the distance be 100 ft between A and B. We can choose the observer anywhere, but let's put Pam 40 ft from A, on the line to B, perfectly measured out with a tape measure. So she is 60 ft from B.

Now let's say Pam sees a flash from A at 1 pm sharp on her clock and a flash from B at 20 ns past 1 pm. The light from A had to take 40 ns to reach Pam, so the coordinate time of strike A is t_A = 1 pm - 40 ns. Likewise the coordinate time for strike B is t_B = 1 pm + 20 ns - 60 ns = 1pm - 40 ns. Hence despite Pam seeing strike A before strike B, in her inertial frame, A and B happened simultaneously.

Can you now see how by altering either the distances and/or the time at which Pam sees the flashes, can cause A to have happened before B or after B? This is how temporal order is determined.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 18th, 2017, 3:13 am 

BurtJordaan » April 18th, 2017, 1:43 am wrote: But where is the observer?

There are 2 observers. One at A and the other at B.

There are 2 clocks at A and B which have been previously been synchronised.

The clocks are stopped at the exact moment of the flash and the times compared later.

It happens exactly as I have stated. It doesnt matter, nano seconds or feet, the fact is that the time interval between the two lightening flashes is less than the time it would take for light to travel from A to B.

How would you tell the order in which the two events happened?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 18th, 2017, 3:31 am 

BurtJordaan on April 18th, 2017, 12:49 am wrote: Not quite. Although mental constructs, a Minkowski inertial frame is defined by a non-rotating, non-accelerated, non-expanding lattice of fictitious standard rods and synchronized clocks, somewhere in empty space. Observers can be either stationary in such a frame, or be moving relative to it. And such inertial frames can be in motion relative to each others. In cosmology, we normally set such inertial frames to be co-moving with the Hubble flow, meaning any observer static such a frame, will observe an isotropic cosmic background radiation (CMB), with the same average temperature in all directions.

Would you agree that “objects” are real? (Be they stars, galaxies, atoms or fundamental particles?).

Would you also agree that a “mental construct” is something fictitious? As is a fictitious, non-rotating, non-accelerated, non-expanding lattice, of fictitious standard rods, and (fictitious) synchronized clocks, somewhere in empty space?

Since we are doing mental visualisations, suppose some of these lattices, in empty space, have no body in it, how would you define the location of this lattice?

It is undoubtedly useful to construct such fictitious lattices to calculate the motion of bodies, (provided there are bodies in them), but it seems to me the fundamental thing here are the bodies themselves.

I could more fundamentally say, if I have a set of bodies that are not in relative motion with each other and observe the CMB the same in all directions, then they are comoving with the Hubble flow. I could then construct an imaginary lattice, with your fictitious rods and clocks, around them, so that this lattice is not in relative motion with them, and that would be the “mental construct” that you are talking about.

Unless you can convince me otherwise, I am quite clear in my mind that, in the ultimate analysis, bodies define the lattice and not the other way around.

BurtJordaan on April 18th, 2017, 12:49 am wrote: The math of GR can be formulated with a pre-choice of a time axis as part of its 4-D, or without that pre-choice being made. It makes no difference to the outcome. To a trained GR-specialist, it is perfectly clear how to get the time coordinate out of the Einstein field equations during the process of solving them. In the cosmological solution, a time coordinate falls out in a pretty obvious fashion.

I don’t quite understand what you are saying here. Are you saying that time disappears in the GR solutions?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 18th, 2017, 8:24 am 

rajnz00 » 18 Apr 2017, 09:13 wrote:It happens exactly as I have stated. It doesnt matter, nano seconds or feet, the fact is that the time interval between the two lightening flashes is less than the time it would take for light to travel from A to B.

OK, I see what you mean - the spacetime interval is spacelike and the order of the two events could be different for specific observers, as Mitchell has pointed out. But, for your observers A and B, in their inertial frame, event A has clearly happened before event B.

However, because the interval is spacelike, for another set of synchronized observers, say C and D, stationary in an inertial frame that moves in the direction A to B, at a relative speed greater than c/3*, event B would have happened before event A. But whatever the relative speed, the two events remain spacelike separated and hence one could never have been the cause of the other one.

I'll leave it here until you are comfortable with this answer.

* with B,C moving relative to A,B at c/3, the two events would be simultaneous for B and C.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 18th, 2017, 2:14 pm 

BurtJordaan on April 18th, 2017, 8:24 am wrote: I'll leave it here until you are comfortable with this answer.

Of course, I am comfortable with that answer. There was never a shadow of a doubt in my mind that event A happened before event B. And I care a damn about “observers” whizzing around at breakneck speeds, recording the events, and trying to figure out which one came first.

Also, there are two lightning strikes at two different places, so in the real world, again, lightning strike at A did not cause lightning strike at B. That is obvious. I do not need SR /GR equations to figure that out (or to confuse me).

However further back (in time), in the cloud, the emission of the first lightning burst could well have been the cause of the second lightening burst.

So, from my thought experiment, adapted from Einstein's, I can conclude that:

Even “spacelike” separated events can be/ are ordered in time (proper time?) absolutely and unambiguously, and,

Although, spacelike events cannot be the cause of each other, yet they could be linked to other causes, in which, eventually, one caused the other, and led to a cascade of events which eventually led to the spacelike events happening.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 18th, 2017, 3:16 pm 

rajnz00 » 18 Apr 2017, 20:14 wrote:Even “spacelike” separated events can be/ are ordered in time (proper time?) absolutely and unambiguously, and,

Although, spacelike events cannot be the cause of each other, yet they could be linked to other causes, in which, eventually, one caused the other, and led to a cascade of events which eventually led to the spacelike events happening.

I'm afraid that these conclusions are incompatible with relativity theory, if I understand correctly what you wrote. No sequence of cause and effect can lead to spacelike separated events being causally related in any way.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 18th, 2017, 3:47 pm 

rajnz00 » 18 Apr 2017, 09:31 wrote:Would you agree that “objects” are real? (Be they stars, galaxies, atoms or fundamental particles?).

Yup, and so are rods and clocks. I only said "fictitious" because nobody will ever put such a 'lattice' in space. Maybe "hypothetical" would have been the better word.

It is undoubtedly useful to construct such fictitious lattices to calculate the motion of bodies, (provided there are bodies in them), but it seems to me the fundamental thing here are the bodies themselves.

We usually do the construction on paper, so then there are no physical bodies there... ;) But, you are right that in the real world there are always at least particles (energy), even if it is only light.

I could more fundamentally say, if I have a set of bodies that are not in relative motion with each other and observe the CMB the same in all directions, then they are comoving with the Hubble flow. I could then construct an imaginary lattice, with your fictitious rods and clocks, around them, so that this lattice is not in relative motion with them, and that would be the “mental construct” that you are talking about.

Yes, but my "mental construct" does not depend on the CMB. I can put it anywhere in empty space, where gravity is either uniform, or absent. And it can move inertially in any way I prefer. In relativity parlance it is just an inertial frame of reference and all the provisos are unnecessary.

I don’t quite understand what you are saying here. Are you saying that time disappears in the GR solutions?

Not quite; only if we use the math of tensors in the formulations of the spacetime metric of relativity. In the solutions we normally choose a coordinate system which has one time component. This is rather specialized mathematics and perhaps not suitable for discussion in this section of the forum.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 18th, 2017, 4:14 pm 

BurtJordaan wrote:
rajnz00 » 18 Apr 2017, 20:14 wrote:Even “spacelike” separated events can be/ are ordered in time (proper time?) absolutely and unambiguously, and,

Although, spacelike events cannot be the cause of each other, yet they could be linked to other causes, in which, eventually, one caused the other, and led to a cascade of events which eventually led to the spacelike events happening.

I'm afraid that these conclusions are incompatible with relativity theory, if I understand correctly what you wrote. No sequence of cause and effect can lead to spacelike separated events being causally related in any way.

Why not? The lightening at A and B were caused by something.

Let the final cause of event at A be a1.

Let there be a series of events, going backward in time, a1 was caused by a2,...was caused by a(n-1) was caused by an, every one of them was an actual cause and hence everyone are timelike.

Similarly
Let the final cause of event at B be b1.

Let there be a series of events, going backward in time, b1 was caused by b2,...was caused by b(n-1)

an caused both both a(n-1) and b(n-1), which are all timelike intervals.

A and B are then causally linked. They didnt cause one another, but they are linked to an original cause.

After all everything in the universe is linked to an original cause, why then are you saying it is impossible?

If that is incompatible with relativity theory, then there is something wrong with that part of Relativity theory, as it is being interpreted.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 18th, 2017, 4:42 pm 

I worked it out, you are right

"an caused both both a(n-1) and b(n-1), which are all timelike intervals."

I plugged in some numbers an cannot be timelike with b(n-1)

But do you agree with my first conclusion?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 18th, 2017, 6:42 pm 

Yup, I agree. I'm glad you found the solution. :)
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 18th, 2017, 7:25 pm 

I only agree with your statement that “No sequence of cause and effect can lead to spacelike separated events being causally related in any way”, in accordance with Relativity theory.

But I also believe that Relativity theory is not the last word in our understanding of the universe, just that it greatly enhances our understanding of it, just like Newton did.

One way that it maybe overcome is if tachyons exist and they can be involved in causes in some way.

By first principles every event in the Universe can be traced back to a first cause and they must be causally related, backwards in time, in much the same way as all life is related backwards in time, through a phylogenetic tree.
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 19th, 2017, 2:24 am 

Agreed. ;)
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby rajnz00 on April 19th, 2017, 3:22 pm 

Anti-Gravity?

Technical speak - "A negative effective mass can be realized in quantum systems...." https://journals.aps.org/prl/abstract/1 ... 118.155301

Translated into plain English - "Physicists have created a fluid with "negative mass", which accelerates towards you when pushed." http://www.bbc.com/news/science-environment-39642992

Newton's Second Law - every action has an equal and opposite reaction - this has seemingly been violated?

Negative effective mass? Is it repelled by other masses? Can it be considered as the equivalent of a hydrogen or helium balloon in air, except a "negative mass" in spacetime?
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Re: Questions about Space, Time, Motion, Blackholes and Stuf

Postby BurtJordaan on April 25th, 2017, 12:33 am 

rajnz00 » 19 Apr 2017, 21:22 wrote:Anti-Gravity?
I'm not a particle physicist, but as I understand, "negative effective mass" is just a way to deal with a very complex electron reflection.

PhysicsForums wrote:Physically, the fact that the electron accelerates opposite to the direction of the force is because the electron must reflect off the zone boundary. As it approaches the boundary, it must decelerate. This behavior is of course due to the complex interaction with the periodic potential, but the effective mass serves as a convenient tool to understand how the electron will behave without knowing the details of these internal forces.


Anti-gravity requires 'exotic' (unknown) material with 'real' negative mass, and lots of it.
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