Utopia and Time Travel

[RussDill]

You keep saying universal now. Does that have some sort of scientific definition? Providing an accurate definition would be the first step to determining if such a thing exists.

 

[Navigator]

Like I said...

 

[RussDill]

Like I said...

you mean this definition, "All the different things happening in that moment, and the distance between those things has no bearing on the moment - the universal now."

That's the definition of now. The problem is adding the quantifier "universal". Different inertial observers will have a different list of things that are happening in any given moment. Which inertial frame of reference refers to the universal now?

 

[Mojo]

I am speaking about now in relation to a universal concept, but even one this planet, if you are one one side experiencing a night and I was on the other side experiencing a day, we still experience the same moment, only the subjective experience is different.

Not according to relativity, because they have different velocities.

 

[Roboramma]

I am certain that my point need not be misunderstood.

Objectively, the universe is in a constant state of now, regardless of how it is subjectively observed.

On that, we should all be able to agree on.

The objective reality is the 4-dimensonal spacetime. Relative motion results in different perspectives on those 4 dimensional objects. What you see as time I might see as space, to some extent (and to a greater extent the greater our relative motion).

A very accurate analogy is different people observing objects from different viewpoints: a circle from most angles looks like an ellipse, for instance. In this analogy relative motion is like a rotation of that perspective.

Because we are embedded in this 4 dimensional spacetime there is no objective way to choose a "real" reference frame. All are equally valid and all describe the physics of the universe equally accurately, though depending on the situation one may be more convenient than another.

 

[Roboramma]

The monument can serve as a sundial if it doesn't move. You would set up a radiating index around it like sundials typically have.

But you are going to have a problem if the monument moves like a reed swaying in the winds, or moves around like a live giraffe.

The monument works as a sun dial precisely because it is moving relative to the sun. Specially it is its 24-hour cycle of revolutions around the earth's axis that is being measured by a sun dial.

 

[Roboramma]

There is a common misconception that Navigator may be under regarding the relativity of simultaneity, so just in case I'd like to correct that misconception:

Let's say that you and I are sitting across the room from each other having a conversation. We are not moving relative to one another. For fun we're speaking in sign language. Imagine for a moment that our eyes are so sensitive (and our brains so accurate in processing delays in time) that we are able to notice the tiny delays in speed of light signal time across the distance of a room. We both say hello to one another at the same time, but I notice a delay between me saying "hello" and you saying "hello". You notice the same delay. From this naive view it seems that we can't agree on "now", as we both see the other as having acted after ourselves.

But this isn't what's meant by the relativity of simultaneity. Relativity works just fine with calculating that delay and saying that we both said hello at the same moment. In this example we both observe the other as saying hello at the same moment. So, Navigator, if you think that's what has been suggested as an issue you are right to think that's not a problem for some universal "now".

The problem arises when we go into relative motion. We can go deeper into it, but the short version is that once we are in relative motion we both calculate the other to (for instance) have said hello first. And there is no way to say that one of us is right and the other wrong.

If you think that doesn't make sense, perhaps we can look at an actual example and you can see if you can find some way of determining what the actual order of events is.

 

[alexi_drago]

No. You just require an understanding that the universe is one thing happening in the same moment in relation to objectivity. The understanding can be subjective, but the actuality is objective.

That no individual has the ability to see everything that happens in the universe at any given moment, is besides the point, and there is no need to go outside the universe to have subjective verification that it is one thing. The mind is capable of being able to perceive of such a simple concept, provided that one accepts that the universe is one thing of itself and that all things happening within it are happening simultaneously in relation to that one thing.

In my example, in what order did the signals reach and reflect off the 2 ships? According to the ship in the middle it was simultaneous, another observer might observe the signal reaching the first ship first and another observer might see it reaching the last ship first, which one is correct? They all are, within their own reference frame, to have what you're suggesting, you need some sort of universal reference frame, something like an aether.

 

[alfaniner]

Just watch any live interview between someone in the studio and someone on the other side of the world. The delay is noticeable between any questions asked and answered given because of the distance it takes the signal to travel.

 

[The Greater Fool]

Imagine there are 3 ships in space all in line maintaining equal distance between the 1st and 2nd, and 2nd and 3rd. There is no fixed reference to determine if they are in motion along the direction of the line they lie on.
The one in the middle emits a signal which is reflected back by both the others, the returned signals from both directions are recieved simultaneously by the middle ship regardless of whether they are all in motion or not.
According to the middle ship the reflections occurred simultaneously, but since there is no fixed reference to determine if the ships are moving or not then it's impossible to tell if the reflections did in fact occur simultaneously or if the reflection from one occurred before or after the reflection off the other.
For a universal now, i think you would require a fixed reference to the universe, an aether.

Imagine the two outer ships emit a signal at exactly the same instant.

Did you imagine this? Or were you unable to imagine it?

If you were able to imagine it, that is Navigator's 'universal now'

 

[Pianoro]

Just watch any live interview between someone in the studio and someone on the other side of the world. The delay is noticeable between any questions asked and answered given because of the distance it takes the signal to travel.

To cover the longest distance on the surface of the Earth, light only takes 1/15 of a second. I doubt it would be possible to notice this lag in a human conversation. If a lag is observed, most likely it would be caused by other delays in the transmission system.

Like Roboramma just pointed out (again), observational delays due to large distances have nothing to do with the concept of simultaneity in special relativity. Even very distant events can, rightly, be considered to occur simultaneously, it does not matter that observation is only possible much later.

 

[Hokulele]

Imagine the two outer ships emit a signal at exactly the same instant.

Did you imagine this? Or were you unable to imagine it?

If you were able to imagine it, that is Navigator's 'universal now'

But that is relative to a third position, yours. To the ships, or to a fourth observer, they weren't emitted at exactly the same instant. There is no such thing as a universal "now", any more than there is a spatial universal 0,0,0.

 

[The Greater Fool]

But that is relative to a third position, yours. To the ships, or to a fourth observer, they weren't emitted at exactly the same instant. There is no such thing as a universal "now", any more than there is a spatial universal 0,0,0.

This is the crux of the disconnect.

I didn't say nor imply any person was observing anything. Just as with the other illustrative examples, it is a given that an event (or events) happen in a particular way. In this case, that two signals were created at the same instant.

If you can't imagine two signals being created at the same time, what does imagining two or more observers add? How three observers experience the two signals would be rather meaningless concept if the two signals did not have some objective relationship to each other.

 

[Navigator]

I really am amazed that people are resorting to relativity as if they cannot simply go into their minds and understand such a simple concept without it. I wonder if that happens when people deride the imagination for long enough that they cease to have one.

Yet - if one was to say "They universe would not exist if consciousness did not exist" the same folk have hernias over that.

Go figure.

 

[Pianoro]

I really am amazed that people are resorting to relativity as if they cannot simply go into their minds and understand such a simple concept without it. I wonder if that happens when people deride the imagination for long enough that they cease to have one.

People are resorting to special relativity because it is the best scientific theory we have to provide an answer to a question such as "is there a universal now?". The answer is no.

Intuition, imagination and "common sense" are insufficient tools to understand reality, especially outside the realm of direct human experience.

Within the environment that humans evolved in and directly experience, intuition can sometimes give "correct" answers to "simple" questions. On Earth and for all people on Earth there is indeed a "universal now". Because the relative motions of the various observers are very slow and distances very limited, the effects that give different observers different planes of simultaneity are negligible.

On a cosmological scale, that is not the case and we need (in this case) special relativity, not intuition, to find the correct answer.

 

[Navigator]

People are resorting to special relativity because it is the best scientific theory we have to provide an answer to a question such as "is there a universal now?". The answer is no.

I don't see how special relativity theory was created for that reason. It was created specifically to give coherence in relation to points of consciousness within the universe, not to somehow show that the universe didn't exist in space as a complete thing.

Intuition, imagination and "common sense" are insufficient tools to understand reality, especially outside the realm of direct human experience.

Exactly. Direct human experience. The subjective position within the universe. That was the reason for the math.

Within the environment that humans evolved in and directly experience, intuition can sometimes give "correct" answers to "simple" questions. On Earth and for all people on Earth there is indeed a "universal now". Because the relative motions of the various observers are very slow and distances very limited, the effects that give different observers different planes of simultaneity are negligible.

That is not my argument. By saying that yes for sure, the universe in its completeness is situated in NOW, regardless of individual points of consciousness experiencing that NOW, at different points within it.

Surely that is simple enough for someone to acknowledge without invoking "if the math cannot verify it, then it cannot be the case"
One does not need math to understand such a simple concept.

On a cosmological scale, that is not the case...

What is 'not the case?

and we need (in this case) special relativity, not intuition, to find the correct answer.

In what 'case'?

Are you thus agreeing with me that the universe exists as a whole thing, and that whole thing exist within the moment NOW?

 

[The Greater Fool]

People are resorting to special relativity because it is the best scientific theory we have to provide an answer to a question such as "is there a universal now?". The answer is no.

Based on Navigator's statements, I interpret the "Universal Now" to be the objective state of the universe at a given instant.

SR explains how observers would subjectively experience this objective universe.

 

[Navigator]

Based on Navigator's statements, I interpret the "Universal Now" to be the objective state of the universe at a given instant.

SR explains how observers would subjectively experience this objective universe.

Finally ! Someone who is able to understand what is such a simple concept.

The arguments against the universe existing of itself in NOW (as related to time) tend toward the conclusion that without consciousness within the universe, the universe wouldn't exist.

What I am saying is that without consciousness within the universe, the universe may as well not exist.

Big difference right there.

But...perhaps the math says otherwise and this is what peps are arguing?

We shall see...

 

[Pianoro]

I don't see how special relativity theory was created for that reason. It was created specifically to give coherence in relation to points of consciousness within the universe, not to somehow show that the universe didn't exist in space as a complete thing.

Special relativity was created to make mechanics consistent with electrodynamics, and specifically to modify mechanics so that Lorentz instead of Galilean invariance applies (i.e. remove the assumption that time is independent of the observer).

That is not my argument. By saying that yes for sure, the universe in its completeness is situated in NOW, regardless of individual points of consciousness experiencing that NOW at different points within it.
Surely that is simple enough for someone to acknowledge without invoking "if the math cannot verify it, then it cannot be the case"
One does not need math to understand such a simple concept.

It's easy enough to understand the concept, it just isn't applicable to our reality. Special relativity does not allow for a "now" independent of an observer. What verifies special relativity are observations, not math.

What is 'not the case?

That a "universal now" exists. It does on Earth, as an approximation.

In what 'case'?

In the case of asking the question "is there a universal now?". The applicable scientific theory that gives an answer to this is special relativity.

Are you thus agreeing with me that the universe exists as a whole thing, and that whole thing exist within the moment NOW?

I am not sure exactly what this means, but if your claim is that a "universal now" independent of an observer exists, then we disagree.

 

[Pianoro]

Based on Navigator's statements, I interpret the "Universal Now" to be the objective state of the universe at a given instant.

SR explains how observers would subjectively experience this objective universe.

Yes, that is my understanding of his/her statements as well.

Through scientific inquiry it has been shown that the ideas of a "universal now" or an objective state of the universe are not part our reality. Mechanics that assume a "universal now", like Newton's do, are incorrect. In order to provide a correct theory of mechanics, special relativity removes this assumption.

To be clear, there is no place for an "objective state" of the universe in special relativity or any other theory that conforms to observations. Special relativity does not just describe a "special subjective case" of how observers experience the universe, it is a universally applicable theory of mechanics.