Utopia and Time Travel

[The Greater Fool]

Without a reference frame we could not describe the movement of the ball.

Just to clarify, "observational reference frame" does not imply a person, though in our case we have assumed one in each. Not sure I communicated this well.

It is revealing that having the complete knowledge of having defined the scenario [the objective view], you are working hard to artificially confine yourself to an 'observational reference frame'.

As this strikes me as... well... unrealistic and less than forthcoming, I think further exploration of the topic will be less than worthwhile.

Thank you for your time.

 

[RussDill]

No - there is the obvious need for beings of consciousness to exist in relation to the theories because measurements are involved and measurements can only be made by beings of consciousness.

What it applies to relates to objects which are not considered conscious, but in that the relationship is still about consciousness re those objects.

Remove consciousness from the equation as a thought experiment, and those objects related to each other are still being viewed in the position of being within the universe and the position of observing the objects is within the universe.

One cannot separate consciousness from the equation and still have those theories.

OK, then do this thought experiment. Give everyone of the earth a dose of anesthesia, enough for everyone to be out for an hour. During this time, do the laws of physics cease to exist? Anyway, this is a sidetrack, whether or not the universe exists independent of sentient beings existing. In any case, if consciousness does have some effect on physical theories, I challenge you to design an experiment to test it's existence.

 

[Roboramma]

You seem to choke when I call (imagining) the entirety of reality an objective frame of reference, so don't call it that. Call it the entirety of reality as it exists, though 'objective view' I should think would cover it. Call it whatever you want when you describe the actual motion of a bouncing ball on a moving train.

Here's what I think you are missing: reality is the entirety of spacetime, not the entirety of space and time as separate things. You are trying to see the whole universe at a particular moment of time, but that doesn't work because space and time are interconnected as spacetime.

Things which are spacelike separated really don't happen in some particular sequence. They happen, and they happen with a relationship to other events, but not in the naive way that you are imagining.

 

[Roboramma]

Here's a simple example to explain the concept:

Draw some shapes on a piece of paper: a square, a triangle, a circle, etc. Just lay them down randomly on the paper. Now, looking at the paper you will see, perhaps, that the triangle is at the bottom whereas the square is at the top of the page.

Walk around to the other side (or simply turn the paper), and now you'll find that the triangle is that the top while the square is at the bottom. Yet nothing about the relationships of the shapes to each other has changed.

The shapes on the page have some properties that are invariant with respect to rotations in my reference frame: the distance from the centre of the square to the centre of the circle, for instance, in invariant with respect to rotation. They also have properties that are reference frame dependent and are not invariant with respect to rotation: for instance their distance from the top or bottom of the page as defined by the page's position in relation to me.

That seems pretty obvious and even silly, but a very interesting thing about our universe is that the distance between two objects and the duration between two events is reference frame dependent, it is simply an arbitrary description of the underlying 4D reality, much like my description of the shapes on my page as nearer to the top or the bottom. There is still an underlying reality, but it is not made of distances and durations, it is made of spacetime separations.

 

[JimOfAllTrades]

It is revealing that having the complete knowledge of having defined the scenario [the objective view], you are working hard to artificially confine yourself to an 'observational reference frame'.

I don’t think it’s artificial though.

Imagine this. A person is on a flat train car. The car is rolling at 5 mph toward a loading dock that is the same height as the surface of the flat car. The person is bouncing a ball straight up and down a few inches from the leading edge of the train car.

Now we can say that in the objective view the ball is “really” bouncing straight up and down, even though to someone watching the flat car go by the ball is moving in arcs and to someone in a jet plane it’s moving backwards. But we know, because we defined the scenario, that objectively it’s “really” just going straight up and down.

But now while the ball is in the air the flat car hits the loading dock and stops. The ball is still moving forward at 5 mph. It now bounces down the dock moving in arcs. No force acted on the ball. Its path (disregarding air resistance and assuming spherical cows) has not changed. But now we would say that objectively the ball is “really” moving in arcs. The only change is the reference frame.

You must specify reference frames when describing movement. No matter how silly it seems most of the time, its true.

 

[psionl0]

So for every individual, there is an individual universe?

Can you explain how these universes superimpose to appear to be one universe?

Can you explain why individuals exist together that way?

eta

Furthermore, how do you explain that scientists Such as J. Richard Gott, professor of astrophysical sciences understand the same SR but still refer to 'the universe' as a singular reality, rather than as you say, 'there is one for every individual'. and thus, no single reality?

It's not surprising that you would attempt to dismiss this as nonsense. Relativity is a difficult concept to grasp and "separate universes" is an imperfect (but descriptive) way to explain it.

Different observers moving relative to on another will still observe the same objects in the universe but because their system of measurements are different in "their universe", their measurements on the object will differ.

You will probably continue to say "nonsense" because that is easier than trying to comprehend the distortions caused by relative motion.

As an aside, define a point in space.

 

[Pianoro]

As another side note, while the thought experiment with the train and the bouncing ball was initially meant to illustrate special relativity, in the last couple of posts I was trying, unsuccessfully, to use it to explain reference frames, the idea that the laws of motion are the same in all (inertial) reference frames and that they (the reference frames) are all equally valid. This is a much older idea introduced by Galileo and thus called Galilean invariance.

What distinguishes the physics of Galileo and Newton from special relativity is that in the former time is universal, while in the latter it is dependent in the reference frame. If Galileo's and Newton's model was correct the "universal now" discussed on the previous pages would exist.

 

[The Greater Fool]

Here's what I think you are missing: reality is the entirety of spacetime, not the entirety of space and time as separate things. You are trying to see the whole universe at a particular moment of time, but that doesn't work because space and time are interconnected as spacetime.

Things which are spacelike separated really don't happen in some particular sequence. They happen, and they happen with a relationship to other events, but not in the naive way that you are imagining.

Yeah, naive, that's me all over.

You think I am ignoring space/time. I am not. Reality, with all it's space/time, still exists as it exists "now" and again "now." Just as you or I exist "now" and "now".

You don't like "now" in relation to reality, but we understand "now" is a state of reality at that specific "now" instant. I guess rather than "now" we should say "space/now."

 

[psionl0]

Reality, with all it's space/time, still exists as it exists "now" and again "now." Just as you or I exist "now" and "now".

Who's "now"?

 

[Navigator]

OK, then do this thought experiment. Give everyone of the earth a dose of anesthesia, enough for everyone to be out for an hour. During this time, do the laws of physics cease to exist? Anyway, this is a sidetrack, whether or not the universe exists independent of sentient beings existing. In any case, if consciousness does have some effect on physical theories, I challenge you to design an experiment to test it's existence.

You obviously are misunderstanding this simple enough concept. You and others who keep arguing against it by using examples which all have the observer in them. I lean toward this being a purposeful ploy. But whatever. *shrugs* its a boring game and wasteful use of intelligence.

 

[psionl0]

You obviously are misunderstanding this simple enough concept. You and others who keep arguing against it by using examples which all have the observer in them. I lean toward this being a purposeful ploy. But whatever. *shrugs* its a boring game and wasteful use of intelligence.

observer =/= sentient being.

 

[Roboramma]

Yeah, naive, that's me all over.

You think I am ignoring space/time. I am not. Reality, with all it's space/time, still exists as it exists "now" and again "now." Just as you or I exist "now" and "now".

You don't like "now" in relation to reality, but we understand "now" is a state of reality at that specific "now" instant. I guess rather than "now" we should say "space/now."

So perhaps you can outline a scenario and explain to me what the state of some system is at a given "now"? Make the system as simple as you like.

Understanding the relativity of simultaneity will make many of the other apparent paradoxes of special relativity very clear and intuitive.

You really should try drawing some spacetime diagrams and seeing how this works. I think you'd find it rather illuminating.

As Pianola said, the example of the ball on the train is an example of Galilean relativity, and it's pretty straightforward and extremely established physics that velocity is relative. So, can you understand how the statement "The ball has a velocity v" for any value of v is dependent upon one's reference frame? This means that the separation in space between two events is also dependent upon one's reference frame: did that ball move up and down over the same point or move in forward moving arcs? This depends upon how one defines one's coordinate system and isn't an intrinsic characteristic of the world. How far is the ball's first bounce from it's second? This depends on one's coordinate system. In special relativity time is also not invariant.

Given that this is extremely well established physics do you agree or disagree with the above?

 

[Roboramma]

I don’t think it’s artificial though.

Imagine this. A person is on a flat train car. The car is rolling at 5 mph toward a loading dock that is the same height as the surface of the flat car. The person is bouncing a ball straight up and down a few inches from the leading edge of the train car.

Now we can say that in the objective view the ball is “really” bouncing straight up and down, even though to someone watching the flat car go by the ball is moving in arcs and to someone in a jet plane it’s moving backwards. But we know, because we defined the scenario, that objectively it’s “really” just going straight up and down.

But now while the ball is in the air the flat car hits the loading dock and stops. The ball is still moving forward at 5 mph. It now bounces down the dock moving in arcs. No force acted on the ball. Its path (disregarding air resistance and assuming spherical cows) has not changed. But now we would say that objectively the ball is “really” moving in arcs. The only change is the reference frame.

You must specify reference frames when describing movement. No matter how silly it seems most of the time, its true.

+1

Very well expressed.

 

[JimOfAllTrades]

You must specify reference frames when describing movement. No matter how silly it seems most of the time, its true.

As a bit of an aside, I'm absolutely fascinated by the fact that all the descriptions of the path of the bouncing ball are equally true. It is moving in a straight line, it is moving in arcs, it going forward and backward, and in some frame it's probably standing still. All equally true. Such a simple situation that shows a tiny bit of the true strangeness of reality. It's just cool.

 

[alexi_drago]

Here's a simple example to explain the concept:

Draw some shapes on a piece of paper: a square, a triangle, a circle, etc. Just lay them down randomly on the paper. Now, looking at the paper you will see, perhaps, that the triangle is at the bottom whereas the square is at the top of the page.

Walk around to the other side (or simply turn the paper), and now you'll find that the triangle is that the top while the square is at the bottom. Yet nothing about the relationships of the shapes to each other has changed.

The shapes on the page have some properties that are invariant with respect to rotations in my reference frame: the distance from the centre of the square to the centre of the circle, for instance, in invariant with respect to rotation. They also have properties that are reference frame dependent and are not invariant with respect to rotation: for instance their distance from the top or bottom of the page as defined by the page's position in relation to me.

That seems pretty obvious and even silly, but a very interesting thing about our universe is that the distance between two objects and the duration between two events is reference frame dependent, it is simply an arbitrary description of the underlying 4D reality, much like my description of the shapes on my page as nearer to the top or the bottom. There is still an underlying reality, but it is not made of distances and durations, it is made of spacetime separations.

I like this, I'd make the paper circular, mark 0 to 360 degrees around the edge and mark various random named points anywhere. From any known angle that you look at it you can list the order of points from closest to furthest. According to navigator you could remove the reference to angles around the edge and somehow imagine the order the points are meant to be in.

 

[The Greater Fool]

So perhaps you can outline a scenario and explain to me what the state of some system is at a given "now"? Make the system as simple as you like.

Am I the only that has used the word "now"? Wow.

Let me look it up...

now
adverb
1. at the present time or moment:
You are now using a dictionary.

2. without further delay; immediately; at once:
Either do it now or not at all.

3. at this time or juncture in some period under consideration or in some course of proceedings described:
The case was now ready for the jury.

4.at the time or moment immediately past:
I saw him just now on the street.

and it goes on and on.

When *I* use the word now, I accept that reality was as it was at the time (err, space/time). Like, well everyone, I can only describe a very small piece of it at any given "now" (err, space/now).

Draw some shapes on a piece of paper: a square, a triangle, a circle, etc. Just lay them down randomly on the paper. Now, looking at the paper you will see, perhaps, that the triangle is at the bottom whereas the square is at the top of the page.

Walk around to the other side (or simply turn the paper), and now you'll find that the triangle is that the top while the square is at the bottom. Yet nothing about the relationships of the shapes to each other has changed.

Again, you illustrate my point. You represented reality on a piece of paper with multiple shapes. No matter where you view the drawings, have they changed location IN REALITY? No. You established the actual [objective] relationships when you put the shapes on the paper. What an observer sees doesn't change the reality of how the shapes appear on the paper.

 

[Roboramma]

Am I the only that has used the word "now"? Wow.

I didn't ask you to define the word, I know what it means. I asked you for a simple scenario with a specific state at a specific point in time. It's not hard.

For instance:

Bob wants to synchronise his clock with his friends, Cindy and Dave. They are all standing on a straight road 1 km apart. Bob is in the middle. They each have a large digital display clock. Bob can look at Cindy and Dave's clocks and see what time they read. Since light takes time to get to him the time when he reads the clock will be slightly later than the time that he reads, but because of the symmetrical situation: Cindy and Dave are both equally distant from Bob, he will know the numbers he sees on their clocks are simultaneous. If Cindy's clock read's 12noon and Dave's clock reads 1 pm he will know that Dave's clock is just set 1 hour ahead, but that at any moment in time the number on Dave's clock will just be 1 hour ahead of Cindy's. He can even tell Dave to reset his clock to 1 hour earlier to synchronise with Cindy's.

It seems pretty straightforward then that, once they have synchronised their clocks in this way, if Cindy's clock reads 2pm now, Dave's also reads 2pm now.

But now let's add in Alice. She is in a spaceship flying down the road at high velocity. Alice sees Bob, Cindy, and Dave moving toward her. Because Bob is moving toward Cindy and away from Dave, it takes longer for a signal to get from Dave to Bob than it takes for a signal to get from Cindy to Bob. This means that if Bob is looking at their two clocks what he sees on Cindy's clock must be from later than what he sees on Dave's clock. If Bob sees both clocks saying 12 noon then Dave's should actually be 11:59:59... some earlier than 12 noon. Clearly this effect will be magnified both by Alice's velocity and the separation between Cindy, Bob, and Dave.

So again, who is right? At what time on Dave's clock is it 12noon on Cindy's? At what time on Cindy's clock can she say now it is 12noon on Dave's?

When *I* use the word now, I accept that reality was as it was at the time (err, space/time). Like, well everyone, I can only describe a very small piece of it at any given "now" (err, space/now).

You can describe as much of the universe as you like at a particular moment. The issue is that the time label is arbitrary and dependent upon reference frame.

Again, you illustrate my point. You represented reality on a piece of paper with multiple shapes. No matter where you view the drawings, have they changed location IN REALITY? No. You established the actual [objective] relationships when you put the shapes on the paper. What an observer sees doesn't change the reality of how the shapes appear on the paper.

We both agree that there is an objective reality. We disagree that it includes simultaneity as a property of systems. Things can be said to be simultaneous in a particular reference frame but not in another, and there is no preferred frame.

 

[The Greater Fool]

I didn't ask you to define the word, I know what it means. I asked you for a simple scenario with a specific state at a specific point in time. It's not hard.

For instance:

Bob wants to synchronise his clock with his friends, Cindy and Dave. They are all standing on a straight road 1 km apart. Bob is in the middle. They each have a large digital display clock. Bob can look at Cindy and Dave's clocks and see what time they read. Since light takes time to get to him the time when he reads the clock will be slightly later than the time that he reads, but because of the symmetrical situation: Cindy and Dave are both equally distant from Bob, he will know the numbers he sees on their clocks are simultaneous. If Cindy's clock read's 12noon and Dave's clock reads 1 pm he will know that Dave's clock is just set 1 hour ahead, but that at any moment in time the number on Dave's clock will just be 1 hour ahead of Cindy's. He can even tell Dave to reset his clock to 1 hour earlier to synchronise with Cindy's.

It seems pretty straightforward then that, once they have synchronised their clocks in this way, if Cindy's clock reads 2pm now, Dave's also reads 2pm now.

You are focusing your example on SR and synchronicity and reference. I don't disagree with SR or anything you say about SR.

You can describe as much of the universe as you like at a particular moment. The issue is that the time label is arbitrary and dependent upon reference frame.

No, I can't describe much of the state of reality at all. Nor have I tried.

You, on the other hand, keep showing me examples of reality (bouncing ball on a moving train, shapes on a paper, something about Bob, Cindy, Dave, and Alice) then showing me how that reality appears from different angles. Yet, the reality you created remains unchanged. ETA: We can understand your examples of pieces of reality, yet we can't understand the similar concept on the whole of reality?

We both agree that there is an objective reality. We disagree that it includes simultaneity as a property of systems. Things can be said to be simultaneous in a particular reference frame but not in another, and there is no preferred frame.

Then what are we arguing about?

What we are arguing about is:
I say there is an objective frame of reference. I can only build this frame logically, because as SR demonstrates, there is no real way we can view the objective frame:

1. Reality;
2. At any instant, reality exists in a specific state;
3. From any real perspective, SR is in charge.
4. No one, no thing that exists that can take in the whole of reality as it exists

I believe we agree to this point. We could stop here and be in happy agreement. And I'm at a loss that the next step is a problem...

Reality happens the way it happens in the sequence in which it happens. I am making no claims about any two or more subsets of reality and how they relate. I am only saying they do, objectively, relate in a specific way, in a specific sequence.

 

[Roboramma]

1. Reality;
2. At any instant, reality exists in a specific state;3. From any real perspective, SR is in charge.
4. No one, no thing that exists that can take in the whole of reality as it exists

The highlighted is wrong and in direct contradiction with special relativity.

If it were not wrong you could, for instance, tell me what the specific state of Dave's clock is when Cindy's reads 12 noon.

We can define a coordinate system and say within that system that at a time t, the universe exists in a particular state. Another coordinate system will show that synchronous with event A, which happens at time t in the original coordinate system, event B is also happening, but in the original coordinate system event B happens at time t+1.

The following are contradictory statements:
1. Both coordinate systems are valid.
2. Events B does not happen after event A in reality.

 

[The Greater Fool]

The highlighted is wrong and in direct contradiction with special relativity.

If it were not wrong you could, for instance, tell me what the specific state of Dave's clock is when Cindy's reads 12 noon.

We can define a coordinate system and say within that system that at a time t, the universe exists in a particular state. Another coordinate system will show that synchronous with event A, which happens at time t in the original coordinate system, event B is also happening, but in the original coordinate system event B happens at time t+1.

The following are contradictory statements:
1. Both coordinate systems are valid.
2. Events B does not happen after event A in reality.

OK.

Thanks for the discussion.