Status of the block universe in the field of physics

citrus burst · 07-11-2012 04:34AM

roosh wrote: »

However, you still didn't "categorically address" the point about reciprocal contractions; you simply stated that the relation between events exhibits hyperbolic geometry; you haven't clarified how it comes to exhibit this hyperbolic geometry; for example, how a clock which is at rest relative to an observer can go from being physically uncontracted for both, to being physically contracted when it starts moving relative to that observer, but remain uncontracted itself. Saying that it displays parabolic geometry is simply a restatement of the thing that is being questioned.

Because of the speed of light being the same in every reference frame.
And every reference frame being correct.

roosh wrote: »

Are you honestly trying to suggest that for two observers, at rest relative to each other, the loudness of the radio is subject to length contraction and time dilation; or that the length contraction and time dilation, which lead to relatively moving observers measuring the speed of light to be the constant c, is due to the motion of the light relative to the air?

No I think what he meant was that like the loudness of a radio, length contractions and time dilation are relative. ie they depend on the situation of the observer. In the case of a radio it will be louder to some standing right next to it relative to some one 5 meters away. Similarly length contractions and time dilation are relative to the velocity of the observer. Some one at rest will observe length contraction/time dilation for a relatively moving frame. That is a spaceship moving relative to an observer will be shorter as measured by the observer, then the spaceship as measured by someone on the ship. The shortness is relative to the speed of the ship as the loudness of the radio is relative to the distance from the radio.

Morbert · 07-11-2012 10:56PM

roosh wrote: »

Apologies, I took the point that you "categorically addressed" to mean the issue of presentism.

However, you still didn't "categorically address" the point about reciprocal contractions; you simply stated that the relation between events exhibits hyperbolic geometry; you haven't clarified how it comes to exhibit this hyperbolic geometry; for example, how a clock which is at rest relative to an observer can go from being physically uncontracted for both, to being physically contracted when it starts moving relative to that observer, but remain uncontracted itself. Saying that it displays parabolic geometry is simply a restatement of the thing that is being questioned.

As I said before (x10000), it is not a physical contraction or dilation. What is physical is the causal structure of events. This structure is hyperbolic. Take the time to study this structure. You will see that the difference between reference frames, and hence the difference between the length of an object, or the passage of time, is a hyperbolic rotation. It is no more physically mysterious than looking at a rubik's cube from different frames of reference and seeing different colours.

And you're still trying to peddle that specious analogy!

Are you honestly trying to suggest that for two observers, at rest relative to each other, the loudness of the radio is subject to length contraction and time dilation; or that the length contraction and time dilation, which lead to relatively moving observers measuring the speed of light to be the constant c, is due to the motion of the light relative to the air?

Because, if not, your analogy isn't representative of the issue.

"How can a radio be both physically loud and quiet at the same time? One of the observers of the radio must be more correct than the other."

krd · 07-11-2012 11:30PM

Morbert wrote: »

As I said before (x10000), it is not a physical contraction or dilation.

No, the contractions and dilations are physical. They're just very difficult for beings like us, who can only imagine 3 dimensions as projections onto 2 dimensional space, to witness, or even imagine. When we imagine 3d objects, it's always just a projection onto a 2d surface. We can know there is a 3rd dimension, but we never witness it directly, as we can't. Maybe we can witness three dimensions when we put objects in our mouths, or when we put parts of ourselves in someone else's mouth, but in terms of our eyes, or what we can see in our minds, we never see beyond two dimensions.

If you were some kind of godlike being, who could see the entire universe instantaneously, both the light, and by some magical instantaneousness everything else - in proper 4d - then you'd see the contractions and dilations.

roosh · 08-11-2012 02:37PM

roosh wrote: »

Maybe if I put it as a stand alone point you won't be able to continue ignoring it:

if you don't have a block universe, what you've got is presentism.

How wrong I was!

Maybe if I repost it, you won't ignore it?!

I'm considering your most recent post; it is certianly food for thought. But this is a separate point.

Morbert · 09-11-2012 07:38PM

krd wrote: »

No, the contractions and dilations are physical. They're just very difficult for beings like us, who can only imagine 3 dimensions as projections onto 2 dimensional space, to witness, or even imagine. When we imagine 3d objects, it's always just a projection onto a 2d surface. We can know there is a 3rd dimension, but we never witness it directly, as we can't. Maybe we can witness three dimensions when we put objects in our mouths, or when we put parts of ourselves in someone else's mouth, but in terms of our eyes, or what we can see in our minds, we never see beyond two dimensions.

If you were some kind of godlike being, who could see the entire universe instantaneously, both the light, and by some magical instantaneousness everything else - in proper 4d - then you'd see the contractions and dilations.

They're not physical. Length contraction is a frame-dependent phenomenon, and physics is independent of the chosen reference frame.

Morbert · 09-11-2012 07:44PM

roosh wrote: »

How wrong I was!

Maybe if I repost it, you won't ignore it?!

It's a completely irrelevant question.

roosh · 10-11-2012 04:13AM

Morbert wrote: »

It's a completely irrelevant question.

It wasn't a question, it was a statement; one which pertains to the question of whether or not the block universe is a logical necessity of Einsteinian relativity or not.

Either the 4D Minkowski spacetime represents a block universe or it represents a "presentist" universe.

Morbert · 12-11-2012 05:12PM

roosh wrote: »

It wasn't a question, it was a statement; one which pertains to the question of whether or not the block universe is a logical necessity of Einsteinian relativity or not.

Either the 4D Minkowski spacetime represents a block universe or it represents a "presentist" universe.

This is getting stranger and stranger.

Again, the question of whether or not there is such a dichotomy is irrelevant. What is relevant is presentism is not a logically necessary inference from relativity.

krd · 12-11-2012 10:01PM

Morbert wrote: »

This is getting stranger and stranger.

Again, the question of whether or not there is such a dichotomy is irrelevant. What is relevant is presentism is not a logically necessary inference from relativity.

I think I know where he's getting this......There's a guy on the internet who claims the "present" is its' own dimension. He claims it "explains everything" but it doesn't really. I think his explanation is that the plane of the present, from whichever direction you're looking at it in Euclidian space is facing towards you - so like a cartoon character, who's been flattened by a steam roller, you can't see them if they're turned on their side.

roosh · 13-11-2012 01:00AM

Morbert wrote: »

This is getting stranger and stranger.

Again, the question of whether or not there is such a dichotomy is irrelevant. What is relevant is presentism is not a logically necessary inference from relativity.

It's really quite simple, and not strange at all; either the block universe is a necessary consequence of Einsteinian relativity, or it is compatible with presentism; that is, either the idea, that past and future co-exist with the present, in 4D spacetime, is a logical necessity of Einteinian reltativity, or Einsteinian relativity is compatible with presentism; because presentism is simply the idea that past and future don't exist.

roosh · 13-11-2012 01:06AM

krd wrote: »

I think I know where he's getting this......There's a guy on the internet who claims the "present" is its' own dimension. He claims it "explains everything" but it doesn't really. I think his explanation is that the plane of the present, from whichever direction you're looking at it in Euclidian space is facing towards you - so like a cartoon character, who's been flattened by a steam roller, you can't see them if they're turned on their side.

I can't say that I'm familiar with said "guy on the internet", or his explanation. Presentism stems from the most fundamental fact of empirical observation, namely that no observer ever has or, dare I say, will ever be able to, make an observation that is not in the present moment. That means that there is no evidence that past and future co-exist in 4D spacetime, that doesn't require us to assume the conclusion.

It also stems from the idea that time doesn't exist; given that we have no way of measuring physical time; because nowhere in the process of a clock is something physical called time actually measured; this means time is more a system of measurement, as opposed to a physical property to be measured. There is no evidence for the existence of time that doesn't require us to assume, a priori, that time exists.

Maximus Alexander · 13-11-2012 01:37AM

roosh wrote: »

It also stems from the idea that time doesn't exist; given that we have no way of measuring physical time; because nowhere in the process of a clock is something physical called time actually measured; this means time is more a system of measurement, as opposed to a physical property to be measured. There is no evidence for the existence of time that doesn't require us to assume, a priori, that time exists.

Surely this is the same as saying that nowhere on a ruler is something physical called distance actually measured.

citrus burst · 13-11-2012 02:47AM

Maximus Alexander wrote: »

Surely this is the same as saying that nowhere on a ruler is something physical called distance actually measured.

I often wonder why people never question why things are spatially separated, yet always question why things are temporarily separate. I mean they wonder how time changes, gets from the past to the present to the future, so to speak, or t1 to t2. But they never wonder why two things are separated by a distance.

Nobody seems to question what distance actually is and what it means.

roosh · 13-11-2012 07:07AM

Maximus Alexander wrote: »

Surely this is the same as saying that nowhere on a ruler is something physical called distance actually measured.

Distance, I think, is a little trickier for us, psychologically, than is time; because spatial dimensions seem so obvious, whereas we only ever experience the present moment, and as such, no temporal dimension.

The point could be argued that "distance" too, is just conceptual, even if physical spatial dimensions aren't; but that wouldn't affect the point about how a clock measures time, or rather, how it doesn't measure a physical, temporal dimension.

roosh · 13-11-2012 07:09AM

citrus burst wrote: »

I often wonder why people never question why things are spatially separated, yet always question why things are temporarily separate. I mean they wonder how time changes, gets from the past to the present to the future, so to speak, or t1 to t2. But they never wonder why two things are separated by a distance.

Nobody seems to question what distance actually is and what it means.

I would say that "time" doesn't change at all; there is an ever changing present moment; what we refer to as "past" and "future" are just psychological constructs.

Would the Pauli exclusion principle add some clarity as to why things are spatially separated?

Maximus Alexander · 13-11-2012 08:18AM

roosh wrote: »

The point could be argued that "distance" too, is just conceptual, even if physical spatial dimensions aren't; but that wouldn't affect the point about how a clock measures time, or rather, how it doesn't measure a physical, temporal dimension.

I don't agree at all. A clock measures time in precisely the same sense that a ruler measures distance. A second is just as clearly a distance between two events as a meter is.

Let me put it to you this way:

Imagine yourself locked in the carriage of a train, which travels east forever. There is no way you can get out, there is no way you can take the controls to reverse the train.

Does everything to the west cease to exist because you are no longer there? Does only your current location in space exist?

No, you are separated from the west by both distance and time.

roosh · 13-11-2012 08:33AM

Maximus Alexander wrote: »

I don't agree at all. A clock measures time in precisely the same sense that a ruler measures distance. A second is just as clearly a distance between two events as a meter is.

Not really though; you can lay a ruler down beside a physical object and clearly see the beginning of the ruler and the end, or the physical dimension that is being measured; a clock only ever exists in the present moment so the only "time" you ever see is now; you don't see the clock extending from the past into the future and measure it thusly.

Maximus Alexander wrote: »

Let me put it to you this way:

Imagine yourself locked in the carriage of a train, which travels east forever. There is no way you can get out, there is no way you can take the controls to reverse the train.

Does everything to the west cease to exist because you are no longer there? Does only your current location in space exist?

No, you are separated from the west by both distance and time.

Imagine I'm not locked in a carriage and can see "the west" even though I'm traveling east forever; I can also see "the east" approaching me; the same cannot be said of time. That is, there is no empirical evidence that "past" and "future" exist, that doesn't require us to assume the conclusion.

But even within the carriage, I can see one end of the carriage, while standing at the other; here the spatial dimensions of the carriage appear to be self-evident; even if this is an illusion, the same cannot be said of time; we only ever experience the present moment.

Maximus Alexander · 13-11-2012 08:39AM

roosh wrote: »

Imagine I'm not locked in a carriage and can see "the west" even though I'm traveling east forever; I can also see "the east" approaching me; the same cannot be said of time. That is, there is no empirical evidence that "past" and "future" exist, that doesn't require us to assume the conclusion.

But even within the carriage, I can see one end of the carriage, while standing at the other; here the spatial dimensions of the carriage appear to be self-evident; even if this is an illusion, the same cannot be said of time; we only ever experience the present moment.

Do you accept that both Africa and America exist, despite the fact that you cannot see them both?

roosh · 13-11-2012 08:41AM

Maximus Alexander wrote: »

Do you accept that both Africa and America exist, despite the fact that you cannot see them both?

I can travel to both; and there's empirical evidence of their existence, that doesn't require me to assume the conclusion*.

*Putting aside any disucussion on whether countries actually exist.

Maximus Alexander · 13-11-2012 08:43AM

roosh wrote: »

I can travel to both; and there's empirical evidence of their existence.

You can not travel to both at once. So, if there is no empirical evidence for time, you cannot accept the fact that you have been to Africa as evidence for its existence.

roosh · 13-11-2012 08:46AM

Maximus Alexander wrote: »

You can not travel to both at once. So, if there is no empirical evidence for time, you cannot accept the fact that you have been to Africa as evidence for its existence.

No, but I can travel to both; I cannot travel to the past or the future.

It is possible that, in the time I have been traveling back from Africa, that it has been eradicated from the face of the earth, but I can set up a sattelite link that allows me to conclude that it existed up until very recently. Again, I can travel back there just to check if it still exists.

I can't do that with either the past or the future.

Maximus Alexander · 13-11-2012 08:48AM

You have travelled from the past to the future. When you read this very post, you'll be in the future, but you're not there yet as I type.

Your experience of the past is no less valid than your experience of Africa, which was in the past.

roosh · 13-11-2012 08:57AM

Maximus Alexander wrote: »

You have travelled from the past to the future. When you read this very post, you'll be in the future, but you're not there yet as I type.

Your experience of the past is no less valid than your experience of Africa, which was in the past.

No, I have always existed in the present, the present is just continually changing. I'm writing this post in the present, and when you read this post it will also be the present moment.

What you refer to as me reading this in the future was just your imagination projecting an image of me reading it; but you were writing it in the present moment and I am reading it in the present moment; what we call the past, that is, your typing the above response only exists in your memory - unless we assume the conclusion.

The difference between between my experience of the past and my experience of Africa is that I can return to Africa whenever I choose - given certain necessary conditions, such as money, transport, etc.

Also, my experience of Africa wasn't in the past, "when I was there" it was the present moment, not this current manifestation of the present moment, but it was former manifestation of the present moment.

The present moment is constantly changing and what we term "the past" is just a memory, and only exists in our imagination - without assuming the conclusion.

"The past" does continue to exist in some sense though, because everything that made up "the past" still exists now, it has just changed shape, so to speak. It's like baking a cake; you get the milk, eggs, butter and flower, and pre-heat the oven. You have the ingredients sitting on the worktop. Then you make your mix and bake your cake. Now, the milk, eggs, flour, and butter all still exist, they just don't exist in their individual packets anymore; the milk carton is in the bin, but it still exists, and all the ingredients still exist, they're just mixed together in the form of a cake.

The future also exists in the same way, because everything that will be in "the future" already exists, just in a different form.

Maximus Alexander · 13-11-2012 09:10AM

roosh wrote: »

"The past" does continue to exist in some sense though, because everything that made up "the past" still exists now, it has just changed shape, so to speak. It's like baking a cake; you get the milk, eggs, butter and flower, and pre-heat the oven. You have the ingredients sitting on the worktop. Then you make your mix and bake your cake. Now, the milk, eggs, flour, and butter all still exist, they just don't exist in their individual packets anymore; the milk carton is in the bin, but it still exists, and all the ingredients still exist, they're just mixed together in the form of a cake.

The future also exists in the same way, because everything that will be in "the future" already exists, just in a different form.

So... this entire discussion is actually about semantics then?

citrus burst · 13-11-2012 09:12AM

roosh wrote: »

I would say that "time" doesn't change at all; there is an ever changing present moment; what we refer to as "past" and "future" are just psychological constructs.

Well how long is the present moment?

roosh wrote: »

Would the Pauli exclusion principle add some clarity as to why things are spatially separated?

I don't think that two fermions cannot exist in the same quantum state, says much about how things are spatially separate.

roosh · 13-11-2012 09:33AM

Maximus Alexander wrote: »

So... this entire discussion is actually about semantics then?

No, it's about the continued physical existence of what we refer to as "the past", and the physical existence of what we term "the future". I say that what we term "past" and "future" do not have any ontological status, the don't co-exist in 4D spacetime along with what we term "the present". To conclude such we would have to assume it.

Maximus Alexander · 13-11-2012 09:39AM

Is that not actually a philosophical discussion though, rather than a physical one?

roosh · 13-11-2012 10:00AM

citrus burst wrote: »

Well how long is the present moment?

Do you mean what length of time does it last?

citrus burst wrote: »

I don't think that two fermions cannot exist in the same quantum state, says much about how things are spatially separate.

Does it not also that only certain combinations of matter can exist in the same space, so assuming that not all matter exists in the same combination, the necessary conclusion would be that they must be spatially separated.

roosh · 13-11-2012 10:01AM

Maximus Alexander wrote: »

Is that not actually a philosophical discussion though, rather than a physical one?

The physical existence of the "past" and "future"? It appears to be a conclusion reached through physics, although it would appear to be a conclusion which has to be assumed.

citrus burst · 13-11-2012 10:13AM

roosh wrote: »

Do you mean what length of time does it last?

yes

roosh wrote: »

Does it not also that only certain combinations of matter can exist in the same space, so assuming that not all matter exists in the same combination, the necessary conclusion would be that they must be spatially separated.

Well matter is either a fermion or a boson. Fermions can't have the same quantum state. There wavefunctions might overlap, but they must be asymmetric

Status of the block universe in the field of physics

Comments