Time Travel... the fly in the ointment

[beero1000]

Of course, he'll definitely see reason now...

 

[untermensche]

To travel to Europe from America you would have to somehow create it whole.

To travel to the Europe that existed in 1960 you most certainly would have to.

Time is the freedom that allows 3 dimensional objects to move and change. It allows travel through space.

You would need some other kind of dimension to travel through time.

A fanciful dimension that doesn't exist.

 

[Juma]

To travel to Europe from America you would have to somehow create it whole.

To travel to the Europe that existed in 1960 you most certainly would have to.

Time is the freedom that allows 3 dimensional objects to move and change. It allows travel through space.

You would need some other kind of dimension to travel through time.

Not really. Space is what allows you to move through space. And you are always travelling through time.

 

[skepticalbip]

To travel to Europe from America you would have to somehow create it whole.

To travel to the Europe that existed in 1960 you most certainly would have to.

Time is the freedom that allows 3 dimensional objects to move and change. It allows travel through space.

You would need some other kind of dimension to travel through time.

A fanciful dimension that doesn't exist.

You are still arguing that Einstein's spacetime is wrong because it doesn't mesh with your understanding of Newton's description of space. Einstein explained for us that we have always had that fourth dimension (the one you are calling fanciful) but had been misidentifying it. You have heard that Newton didn't get it quiet right haven't you?

You really need to google spacetime and read. The past being just right over there-then (we really need some new words for discussing some things) is one thing... however, being able to get to it (so we can unfold Bilby's piece of paper and read it) is a problem we haven't solved yet, maybe we won't.

 

[untermensche]

To travel to the Europe that existed in 1960 you most certainly would have to.

Time is the freedom that allows 3 dimensional objects to move and change. It allows travel through space.

You would need some other kind of dimension to travel through time.

Not really. Space is what allows you to move through space. And you are always travelling through time.

No. If all you have are three dimensions then you cannot have change.

The forth dimension is what allows three dimensional objects to change location, to move and change.

 

[untermensche]

You are still arguing that Einstein's spacetime is wrong because it doesn't mesh with your understanding of Newton's description of space.

That's not at all what I'm arguing.

His linkage of space with time is right.

That in no way implies it is possible to go back to a prior moment in time.

I'm arguing that some are extending way beyond the science and they have not a shred of evidence to allow it.

 

[skepticalbip]

You are still arguing that Einstein's spacetime is wrong because it doesn't mesh with your understanding of Newton's description of space.

That's not at all what I'm arguing.

His linkage of space with time is right.

That in no way implies it is possible to go back to a prior moment in time.

I'm arguing that some are extending way beyond the science and they have not a shred of evidence to allow it.

You seem to have made a major shift of goalposts here. You had maintained that we can't go back to a prior moment because it doesn't exist. Are you now changing that to the past exists but we can't go back to it (for some as yet unspecified by you reason other than that the past doesn't exist)?

I personally wouldn't make absolutist predictions about future science. I am still working on improving my abysmal postdicting record.

The past being just right over there-then (we really need some new words for discussing some things) is one thing... however, being able to get to it (so we can unfold Bilby's piece of paper and read it) is a problem we haven't solved yet, maybe we won't.

 

[bilby]

Not really. Space is what allows you to move through space. And you are always travelling through time.

No. If all you have are three dimensions then you cannot have change.

The forth dimension is what allows three dimensional objects to change location, to move and change.

Only because we move in time with constant velocity. In a four dimensional universe, change in three dimensions is an illusion; nothing changes; we just experience a different point of view as our T coordinate changes - in exactly the same way that our point of view changes with variations in the X, Y and Z coordinates.

To use an analogy in three dimensions, a series of two dimensional slices through a cone, each slice further from the tip than the last, produces the illusion of an expanding two-dimensional circle. But the cone stays the same; only the perspective changes. The circle is a slice of a higher dimensional reality, and change only occurs as an artefact of thinking about the situation in terms only of the two dimensions we are considering at the time.

 

[DBT]

To travel to the Europe that existed in 1960 you most certainly would have to.

Time is the freedom that allows 3 dimensional objects to move and change. It allows travel through space.

You would need some other kind of dimension to travel through time.

A fanciful dimension that doesn't exist.

You are still arguing that Einstein's spacetime is wrong because it doesn't mesh with your understanding of Newton's description of space. Einstein explained for us that we have always had that fourth dimension (the one you are calling fanciful) but had been misidentifying it. You have heard that Newton didn't get it quiet right haven't you?

You really need to google spacetime and read. The past being just right over there-then (we really need some new words for discussing some things) is one thing... however, being able to get to it (so we can unfold Bilby's piece of paper and read it) is a problem we haven't solved yet, maybe we won't.

Well., actually, the idea of spacetime has its problems and different ideas are being put forward by physicists :

'Physicists continue work to abolish time as fourth dimension of space;
''In their paper, Sorli and Fiscaletti argue that, while the concepts of special relativity are sound, the introduction of 4D Minkowski spacetime has created a century-long misunderstanding of time as the fourth dimension of space that lacks any experimental support. They argue that well-known time dilation experiments, such as those demonstrating that clocks do in fact run slower in high-speed airplanes than at rest, support special relativity and time dilation but not necessarily Minkowski spacetime or length contraction. According to the conventional view, clocks run slower at high speeds due to the nature of Minkowski spacetime itself as a result of both time dilation and length contraction. But Sorli and Fiscaletti argue that the slow clocks can better be described by the relative velocity between the two reference frames, which the clocks measure, not which the clocks are a part of. In this view, space and time are two separate entities.''


“The definition of time as a numerical order of change in space is replacing the 106-year-old concept of time as a physical dimension in which change runs,” Sorli said. “We consider time being only a mathematical quantity of change that we measure with clocks. This is in accord with a Gödel view of time. By 1949, Gödel had produced a remarkable proof: 'In any universe described by the theory of relativity, time cannot exist.' Our research confirms Gödel's vision: time is not a physical dimension of space through which one could travel into the past or future.”

 

[beero1000]

You are still arguing that Einstein's spacetime is wrong because it doesn't mesh with your understanding of Newton's description of space. Einstein explained for us that we have always had that fourth dimension (the one you are calling fanciful) but had been misidentifying it. You have heard that Newton didn't get it quiet right haven't you?

You really need to google spacetime and read. The past being just right over there-then (we really need some new words for discussing some things) is one thing... however, being able to get to it (so we can unfold Bilby's piece of paper and read it) is a problem we haven't solved yet, maybe we won't.

Well., actually, the idea of spacetime has its problems and different ideas are being put forward by physicists :

'Physicists continue work to abolish time as fourth dimension of space;
''In their paper, Sorli and Fiscaletti argue that, while the concepts of special relativity are sound, the introduction of 4D Minkowski spacetime has created a century-long misunderstanding of time as the fourth dimension of space that lacks any experimental support. They argue that well-known time dilation experiments, such as those demonstrating that clocks do in fact run slower in high-speed airplanes than at rest, support special relativity and time dilation but not necessarily Minkowski spacetime or length contraction. According to the conventional view, clocks run slower at high speeds due to the nature of Minkowski spacetime itself as a result of both time dilation and length contraction. But Sorli and Fiscaletti argue that the slow clocks can better be described by the relative velocity between the two reference frames, which the clocks measure, not which the clocks are a part of. In this view, space and time are two separate entities.''


“The definition of time as a numerical order of change in space is replacing the 106-year-old concept of time as a physical dimension in which change runs,” Sorli said. “We consider time being only a mathematical quantity of change that we measure with clocks. This is in accord with a Gödel view of time. By 1949, Gödel had produced a remarkable proof: 'In any universe described by the theory of relativity, time cannot exist.' Our research confirms Gödel's vision: time is not a physical dimension of space through which one could travel into the past or future.”

I won't go as far to say "crackpot" but "fringe" doesn't quite capture it...

 

[DBT]

Well., actually, the idea of spacetime has its problems and different ideas are being put forward by physicists :

'Physicists continue work to abolish time as fourth dimension of space;
''In their paper, Sorli and Fiscaletti argue that, while the concepts of special relativity are sound, the introduction of 4D Minkowski spacetime has created a century-long misunderstanding of time as the fourth dimension of space that lacks any experimental support. They argue that well-known time dilation experiments, such as those demonstrating that clocks do in fact run slower in high-speed airplanes than at rest, support special relativity and time dilation but not necessarily Minkowski spacetime or length contraction. According to the conventional view, clocks run slower at high speeds due to the nature of Minkowski spacetime itself as a result of both time dilation and length contraction. But Sorli and Fiscaletti argue that the slow clocks can better be described by the relative velocity between the two reference frames, which the clocks measure, not which the clocks are a part of. In this view, space and time are two separate entities.''


“The definition of time as a numerical order of change in space is replacing the 106-year-old concept of time as a physical dimension in which change runs,” Sorli said. “We consider time being only a mathematical quantity of change that we measure with clocks. This is in accord with a Gödel view of time. By 1949, Gödel had produced a remarkable proof: 'In any universe described by the theory of relativity, time cannot exist.' Our research confirms Gödel's vision: time is not a physical dimension of space through which one could travel into the past or future.”

I won't go as far to say "crackpot" but "fringe" doesn't quite capture it...

Maybe, but the nature of time has still not been fully explained.

The past is just recorded memory and future does not exist. The only experience we have of 'time' is an ever changing present moment, which our clocks measure as the rate of change (local).

Perhaps you are able explain the nature of time?


''Efforts to understand time below the Planck scale have led to an exceedingly strange juncture in physics. The problem, in brief, is that time may not exist at the most fundamental level of physical reality. If so, then what is time? And why is it so obviously and tyrannically omnipresent in our own experience? “The meaning of time has become terribly problematic in contemporary physics,” says Simon Saunders, a philosopher of physics at the University of Oxford. “The situation is so uncomfortable that by far the best thing to do is declare oneself an agnostic.”

 

[Speakpigeon]

Time is the freedom that allows 3 dimensional objects to move and change. It allows travel through space.

You would need some other kind of dimension to travel through time.

A fanciful dimension that doesn't exist.

Interesting idea.

Still, space could be the dimension that allows you to travel through time.

And one can argue that we are already travelling through time, in the direction of the future, without any apparent need for another dimension for achieving that.
EB

 

[Speakpigeon]

Space is what allows you to move through space.

Well, moving really seems always to take time. The way we move through space, we need time.

What about photons though? To a photon, its moving from A to B doesn't require time at all. Looking from the outside, though, a photon isn't everywhere at once and does take time to go from A to B.

So, if time is relative, isn't that saying that it doesn't really exist as such?
EB

 

[Juma]

Space is what allows you to move through space.

Well, moving really seems always to take time. The way we move through space, we need time.

What about photons though? To a photon, its moving from A to B doesn't require time at all. Looking from the outside, though, a photon isn't everywhere at once and does take time to go from A to B.

So, if time is relative, isn't that saying that it doesn't really exist as such?
EB

Position is relative.

 

[Speakpigeon]

No. If all you have are three dimensions then you cannot have change.

The forth dimension is what allows three dimensional objects to change location, to move and change.

Only because we move in time with constant velocity. In a four dimensional universe, change in three dimensions is an illusion; nothing changes; we just experience a different point of view as our T coordinate changes - in exactly the same way that our point of view changes with variations in the X, Y and Z coordinates.

To use an analogy in three dimensions, a series of two dimensional slices through a cone, each slice further from the tip than the last, produces the illusion of an expanding two-dimensional circle. But the cone stays the same; only the perspective changes. The circle is a slice of a higher dimensional reality, and change only occurs as an artefact of thinking about the situation in terms only of the two dimensions we are considering at the time.

Ach, that's exactly the kind of angle I've tried to work out since ages and ages but you see it doesn't really work too well. The problem is that you still need to explain the changing of the T coordinate. We can imagine a still universe with four coordinates as you say, one being T, and sure our experience is dependent on the T coordinate. However, in your model, there is no longer any reason for us to be conscious of any one particular point in space-time and there is no longer any reason not to be conscious of all space-time points (not all together, all separately). You would also have to explain the apparent relation of cause and effect. Since everything is still, why would there be a relation between the universe at T and the universe at T + 1?
EB

 

[skepticalbip]

I won't go as far to say "crackpot" but "fringe" doesn't quite capture it...

Maybe, but the nature of time has still not been fully explained.

The past is just recorded memory and future does not exist. The only experience we have of 'time' is an ever changing present moment, which our clocks measure as the rate of change (local).

Perhaps you are able explain the nature of time?


''Efforts to understand time below the Planck scale have led to an exceedingly strange juncture in physics. The problem, in brief, is that time may not exist at the most fundamental level of physical reality. If so, then what is time? And why is it so obviously and tyrannically omnipresent in our own experience? “The meaning of time has become terribly problematic in contemporary physics,” says Simon Saunders, a philosopher of physics at the University of Oxford. “The situation is so uncomfortable that by far the best thing to do is declare oneself an agnostic.”

While it is true that it is a bitch trying to get a handle on the nature of time, I find it just as difficult to try to get a handle on any of the other dimensions. Try painting a mental image of an X-axis all by itself without respect to the other dimensions. Now try explaining the "nature" of that dimension.

Models like spacetime or any other model are not necessarily “reality”, whatever the hell that is. Models are mathematical constructs that allow us to predict events and to “understand” the connections between events. Modeling time as a fourth dimension has proven to be better at allowing us to do this than any other model so far. Does that mean it is “reality”? Not necessarily, but it is the best at predicting events in “reality” we have yet found

 

[Speakpigeon]

Well, moving really seems always to take time. The way we move through space, we need time.

What about photons though? To a photon, its moving from A to B doesn't require time at all. Looking from the outside, though, a photon isn't everywhere at once and does take time to go from A to B.

So, if time is relative, isn't that saying that it doesn't really exist as such?
EB

Position is relative.

Ok so space doesn't exist either.

Fine with me.

What does exist, though?
EB

 

[Juma]

Position is relative.

Ok so space doesn't exist either.

Fine with me.

What does exist, though?
EB

What does "exist" mean to you? To me "space-time is a working model " = "space-time exist"

 

[Speakpigeon]

Equally, it is impossible to tell whether or not the past exists in a four dimensional spacetime (or even whether the fourth dimension itself is 'real') by reference to the three dimensional space we can observe.

According to the empirical method the past exists because we have very many first-hand witness accounts about it. We have nearly all been there, we have observed the past, we have memorised how it looks like, we have recorded data about it in our information systems. We have accumulated more than enough evidence to claim that the past does exist. It's not really scientific because we can't reproduce any observation of the past. Well, you need to be there (then) to observe the past. And so the problem is we don't know how to go back to it to dupplicate observations. If space-time is still as you suggested then we can't go back to a point in time when we weren't there in the first place so no time-travel. Just the impression of travelling in the direction of the future. But maybe space-time is folded unto itself in such a way that here and there (now and then) there is a merging of big chunks of space-time from the future and from the past. That's probably against some law about entropy but maybe the law is wrong.
EB

 

[Speakpigeon]

Ok so space doesn't exist either.

Fine with me.

What does exist, though?
EB

What does "exist" mean to you? To me "space-time is a working model " = "space-time exist"

To me "exist" means what it means for all of us based on empirical evidence, as for example for Descartes: I think therefore I exist. Our notion of existence is based on our own perceived existence, not as legal or moral person but as a thinking thing here and now. From this we extend the notion of existence speculatively to other things like trees, people and God. The existence of time or space is in this respect also speculative. We only know the now and here, not the then and there. So I don't think the existence of time or space should be regarded as a given. Rather, they appear to be constructs of our mind to make sense of our perceptions of the world. So, not far from you view perhaps. To me, space-time is probably just a working model. It exists as a model but we shouldn't confuse the model and whatever it may be the model of.
EB