Register to reply

Block Universe Implications

by Chestermiller
Tags: block, implications, universe
Share this thread:
DaleSpam
#55
Jul9-12, 11:34 AM
Mentor
P: 16,947
Quote Quote by Vandam View Post
People who accept the real significance of "relativity of simultaneity" know that Block Universe is a fact.
There is no experiment which can be performed to distinguish the block universe interpretation of SR from other interpretations of SR. So, no, it is not a fact, even given the relativity of simultaneity. The block universe happens to be my prefered interpretation, but I am not deluded enough to call it a fact.
nitsuj
#56
Jul9-12, 11:55 AM
P: 1,097
Quote Quote by DaleSpam View Post
The block universe happens to be my prefered interpretation,
and then it was and lastly but then 'cause this ground has been covered many times.

I wouldn't have guessed you to prefer an Eternalism interpretation of time.
DaleSpam
#57
Jul9-12, 12:20 PM
Mentor
P: 16,947
Quote Quote by nitsuj View Post
and then it was and lastly but then 'cause this ground has been covered many times.

I wouldn't have guessed you to prefer an Eternalism interpretation of time.
Sorry to cause such distress!

I probably should mention that my preference is practical rather than philosophical. Specifically, I simply find it easier to correctly work most problems by using the block universe interpretation to organize my thinking than by using others. I don't particularly "believe in" any interpretation philosophically and so I shamelessly use other interpretations (even LET) whenever they suit the particular problem at hand.
nitsuj
#58
Jul9-12, 12:43 PM
P: 1,097
Quote Quote by DaleSpam View Post
Sorry to cause such distress!

I probably should mention that my preference is practical rather than philosophical. Specifically, I simply find it easier to correctly work most problems by using the block universe interpretation to organize my thinking than by using others. I don't particularly "believe in" any interpretation philosophically and so I shamelessly use other interpretations (even LET) whenever they suit the particular problem at hand.


Now that's a "Dalespam" response, thanks I feel better now!
bobc2
#59
Jul9-12, 08:50 PM
P: 848
Quote Quote by Vandam View Post
People who accept the real significance of "relativity of simultaneity" know that Block Universe is a fact.
Vandam, you are actually in pretty good company, embracing the Block Universe concept: Physicists and mathematicians like Einstein, Hermann Weyl, Kurt Godel, and many others. Einstein commented that General Relativity would not have got any father than its long clothes without Minkowski's 4-dimensional continuum of special relativity.
PeterDonis
#60
Jul9-12, 09:14 PM
Physics
Sci Advisor
PF Gold
P: 6,034
Quote Quote by bobc2 View Post
Einstein commented that General Relativity would not have got any father than its long clothes without Minkowski's 4-dimensional continuum of special relativity.
I don't think Einstein was talking about the "block universe" concept in that quote, at least not as "block universe" is being used in this thread. "Block universe" is an *interpretation* of what 4-d spacetime, as it's used in SR and GR, means. Einstein was just talking about the theoretical usefulness of 4-d spacetime, in particular how viewing it as a geometric object opened the door to letting that geometric object be dynamic instead of fixed, which led to GR. Einstein was not talking about any particular interpretation of what 4-d spacetime means.
bobc2
#61
Jul9-12, 10:13 PM
P: 848
Quote Quote by PeterDonis View Post
I don't think Einstein was talking about the "block universe" concept in that quote, at least not as "block universe" is being used in this thread. "Block universe" is an *interpretation* of what 4-d spacetime, as it's used in SR and GR, means. Einstein was just talking about the theoretical usefulness of 4-d spacetime, in particular how viewing it as a geometric object opened the door to letting that geometric object be dynamic instead of fixed, which led to GR. Einstein was not talking about any particular interpretation of what 4-d spacetime means.
In my response to Vandam's post I was trying to assure him that he is not alone in his feelings about the block universe. And there is some support for the view that Einstein embraced the concept. Here are excerpts from the other block universe link the you mentioned earlier. They go to the notion that Vandam should not feel alone in his views.

Paul Davies: The idea that events in time are laid out ‘all at once’ motivated Einstein to write the words… “The distinction between past, present and future is only an illusion, even if a stubborn one.”

Paul Davies: “…there is only one rational conclusion to draw from the relative nature of simultaneity: events in the past and future have to be every bit as real as events in the present.”

Paul Davies: “Einstein himself wasn’t too thrilled with the unified spacetime idea at first, dismissing Minkowski’s new four-dimensionality as ‘superflous’ pedantry, but he came around to the idea in due course.”

Paul Davies: ”Weyl once wrote: ‘The world does not happen, it simply is.’ If you believe Weyl, Einstein did; hence the quote penned in consolation to Besso’s widow following his death: ‘The distinction between past, present and future is only an illusion, even if a stubborn one.’

Paul Davies: “In their professional lives most physicists accept without question the concept of the block time, but away from work they act like everybody else, basing their thoughts and actions on the assumption of a moving present moment.”

Paul Davies: “I have already explained how the theory of relativity leads to the notion of block time, and the picture of time as the fourth dimension simply ‘laid out all at once.’ Since Einstein, physicists have generally rejected the notion that events ‘happen,’ as opposed to merely exist in the four-dimensional spacetime continuum.”

Paul Davies: “David Park is a physicist and philosopher at Williams College in Massachusetts with a lifelong interest in a time which he too thinks doesn’t pass. For Park, the passage of time is not so much an illusion as a myth, ‘because it involves no deception of the senses… One cannot perform any experiment to tell unambiguously whether time passes or not.’ “

“When it comes to the truly objective properties of the world, reference to the flow of time appears superfluous.”

Paul Davies: “Einstein scuttled the notion of a universal now, and pointed the way to ‘block time,’ in which all events—past, present and future—are equally real. To the physicist, human beings of the twenty-fifth century are ‘there’… They are there in the future.”
nitsuj
#62
Jul9-12, 10:24 PM
P: 1,097
Quote Quote by bobc2 View Post
Vandam, you are actually in pretty good company, embracing the Block Universe concept: Physicists and mathematicians like Einstein, Hermann Weyl, Kurt Godel, and many others. Einstein commented that General Relativity would not have got any father than its long clothes without Minkowski's 4-dimensional continuum of special relativity.
I've read some wiki about "block universe"; it is seems to me to be a sort of "anti-continuum".

I am of the mind set the universe is a 4D continuum, and not a static block that plays tricks with the measurements/observations we make of time, noting a distinct (but not absolute) future-past continuum.

From the "perspective" of EM and whatever else maybe at that end of the time/length "spectrum" eternalism seems fine to me. I kinda like the PoV that "energy" "flows" at c, and from a causation perspective is an example of "eternalism". but isn't that,clearly, only one perspective of multiple measurable/observable dimensions?

imo bobc2, I think both physically & philosophically our minds have a better grasp of the 4D's, specifically time, than you give it credit for.

Paul Davies: The idea that events in time are laid out ‘all at once’ motivated Einstein to write the words… “The distinction between past, present and future is only an illusion, even if a stubborn one.”

RoS is plenty for all those "Einstein tidbits" in your #61 post, "Eternalism" is just some added poetry, added after the poor fellow cannot speak for himself. In addition I would guess Einstein was purposefully coy with that comment.
Austin0
#63
Jul9-12, 10:35 PM
P: 1,162
Quote Quote by bobc2 View Post
But the point of the space-time diagram is that both events, R1 and R2, exist and are real, and the Red guy exists and is real at both R1 and R2 events. That is, when the brown guy and the blue guy meet, R1 exists in Blue's instaneous 3-D world while R2 exists in Brown's instantaneous simultaneous world.

Don't overcomplicate the problem by asking what you mean by real. I think we all know what we are talking about. We simply use a protype example of real. When Blue and Brown meet, Brown observes that Blue is a real observer and Blue observes that Brown is a real observer. If you and I are standing in a room talking, I identify you as a real body and you identify me as a real body--that's our prototype example of real--unless you are a Solipsist--but Einstein was quite emphatic about prohibiting solipsism in relativity).

Now, it is not a question of whether Brown or Blue correctly identifies the Red observer as being real. Both Brown and Blue are correct in observing that a real Red body exists in their respective 3-D worlds at the event of Brown's and Blue's world lines intersecting (Brown and Blue meet).

That's the whole point of the block concept: the Red body must be a 4-dimensional body for both Brown and Blue to each have Red existing as a 3-D body in their respective instantaneous 3-D worlds. Brown and Blue each observe a different 3-D cross-section of Red's 4-dimensional body.


Again, by extension, we could keep adding more and more observers with different Lorentz boosts until the original Red world line is seen to be a continuous 4-dimensional body, i.e., a real physical body extending continuously along Red's world line. We could then develop the concept for every other observer and every other object in the universe until we recognize the entire universe is 4-dimensional populated by 4-dimensional objects. That's the block universe concept.


I thought you got the concept in that other thread that simultaneity was not transitive in SR So R1 being simultaneous to R according to Blue's clocks and R2 being simultaneous to R by Browns clocks does NOT mean that R1 and R2 are simultaneous.
Any such statement is totally in contradiction of fundamental SR which says that any evaluation of distant events regarding temporal relationship is purely conventional and without any real temporal meaning.
In this case Both Red and Brown would disagree with Blue that R1 and R were simultaneous.
Both Red and Blue would disagree with Brown that R2and R were simultaneous.

So you have just selectively chosen two arbitrary frame evaluations of a set of events,applied an interpretation of actual simultaneity to the clocks in both Blue and Brown systems which is against the principles of SR and then concluded that this is proof that SR necessarily implies a Block Universe.
To me this appears self evidently circular. Applying the block time interpretation and expectations to SR to prove block time,ignoring the fact that this contradicts fundamental SR principles in the process.
bobc2
#64
Jul9-12, 10:48 PM
P: 848
Quote Quote by nitsuj View Post
I've read some wiki about "block universe"; it is seems to me to be a sort of "anti-continuum".

I am of the mind set the universe is a 4D continuum, and not a static block that plays tricks with the measurements/observations we make of time (past-future).
Hi, nitsuj. It's always good reading your posts. Actually, the block universe concept is definitely based on the continuum concept. Einstein never would relenquish his continuum, and insisted it must be that way. I recall a specific reference, but will have to look it up to make sure I'm presenting it correctly.

Quote Quote by nitsuj View Post
From the "perspective" of EM and whatever else maybe at that end of the time/length "spectrum" eternalism seems fine to me, but isn't that,clearly, only one perspective of multiple measurable/observable dimensions?

imo bobc2, I think both physically & philosophically our minds have a better grasp of the 4D's, specifically time, than you give it credit for.
You may have a good point there. I have trouble working through the concept of time as the 4th dimension and various observers having different cross-section views of space-time, with different "mixtures" of space and time.

I can easily handle the process of watching a woven waste basket sitting statically over in the corner of my room while time is passing. But, it's much easier for me to handle conceptually by thinking of the basket extended into the 4th dimension as a 4-dimensional structure (the spaghetti-like picture represented by the world line extending 10^13 miles along the 4th dimension).

In that picture the 4-dimensions are all spatial and the 4-D basket just sits in 4-D space while time passes. But, evidently, that is not the picture that Einstein and all physicists subscribe to. So, in that sense, I'm presenting a speculative concept, which I really don't wish to do on this forum. Einstein definitely refers to space-time with time as the 4th dimension (I know of a reference for this comment, but again it would take a little while to dig it up).
nitsuj
#65
Jul9-12, 11:18 PM
P: 1,097
I had typed up a somewhat lengthy post explaining my interpretation and how it's not compatible with "eternalism".

But luckily had re-read Dalespams post a realized I was merely being opinionated in a physics thread.

bobc2 I do find the Block Universe interpretation fascinating, but philosophically (and from a physics perspective) I don't subscribe.

I am sure you can appreciate the difficulty in conveying such a complex interpretation as "eternalism" in particular via typing it out. You seem to have a deep grasp of the Block Universe Concept and feel strongly about it. Who am I to try and "knock" that, I have no authority on the subject.

So this is all that is left of that "lengthy" post.
harrylin
#66
Jul10-12, 04:13 AM
P: 3,181
Quote Quote by bobc2 View Post
Vandam, you are actually in pretty good company, embracing the Block Universe concept: Physicists and mathematicians like Einstein, Hermann Weyl, Kurt Godel, and many others. Einstein commented that General Relativity would not have got any father than its long clothes without Minkowski's 4-dimensional continuum of special relativity.
Hi Bob, if you refer to his early comments about GR then that's certainly a misinterpretation of what he meant as he did not want to suggest anything philosophical - quite the contrary as Peterdonis suggested:

"Space is a three-dimensional continuum. [..] the world of physical phenomena which was briefly called "world" by Minkowski is naturally four dimensional in the space-time sense. For it is composed of individual events, each of which is described by four numbers".
See: http://www.bartleby.com/173/17.html

And for a discussion of Paul Davies we have your other thread.
DaleSpam
#67
Jul10-12, 04:36 AM
Mentor
P: 16,947
Quote Quote by bobc2 View Post
Vandam, you are actually in pretty good company, embracing the Block Universe concept: Physicists and mathematicians like Einstein, Hermann Weyl, Kurt Godel, and many others. Einstein commented that General Relativity would not have got any father than its long clothes without Minkowski's 4-dimensional continuum of special relativity.
So what? You can take any position on any topic and compile a similar list of "good company". Particularly if you are willing to take quotes out of context.
DaleSpam
#68
Jul10-12, 04:46 AM
Mentor
P: 16,947
Quote Quote by bobc2 View Post
In that picture the 4-dimensions are all spatial and the 4-D basket just sits in 4-D space while time passes.
That picture is wrong. The signature is -+++, not ++++, so the dimensions are not all spatial.
bobc2
#69
Jul10-12, 06:54 AM
P: 848
Quote Quote by nitsuj View Post
I had typed up a somewhat lengthy post explaining my interpretation and how it's not compatible with "eternalism".

But luckily had re-read Dalespams post a realized I was merely being opinionated in a physics thread.

bobc2 I do find the Block Universe interpretation fascinating, but philosophically (and from a physics perspective) I don't subscribe.

I am sure you can appreciate the difficulty in conveying such a complex interpretation as "eternalism" in particular via typing it out. You seem to have a deep grasp of the Block Universe Concept and feel strongly about it. Who am I to try and "knock" that, I have no authority on the subject.

So this is all that is left of that "lengthy" post.
Nitsuj, I certainly have no more authority on the subject than you and would be embarrassed to think anyone would think I considered myself to have more access to truth than anyone else here.

Besides, there are experienced physicists around here, whereas I spent only a year or so as a college physics instructor (undergraduate courses only) and since have had a career limited to applied classical physics with no work at all related to special relativity or QM. You've probably been exposed to more relativity topics from your years on the forum than I have (probably less than a year on the forum for me).

In any case these discussions have nothing to do with me, and my personal views are not relevant. I've tried mainly to present concepts expressed by real physicists to help new visitors to the site find a wider range of views that are out there in the physics community. DaleSpam, harrylin and PeterDonis have fairly called me out on the speculative comments, and I need to be more careful there.
Vandam
#70
Jul10-12, 07:33 AM
P: 126
4D spacetime consists of events. Events are the buiding blocks, permanantly available to be part of a 'now'world. A 'now' world is your world at a specific point in time.
How one's worldline runs through spacetime determines which events out of total spacetime you will select as being 'simultaneous'. Our 3D world is a construction (made by ourselves) of a limited collection of in spacetime permanently available events. This collection is your world during a split second in your life. In spacetime there are no 'simultaneous' events as such, because 'simultaneity' is something we stick onto the events that we consider happening the same time. Other people will put the simultaneity sticker to oher events.
Whether a world at a specific point in time (= per definition made of simultaneous events) is 'physical' or 'real' is not that important (this gets philosophical), BUT if you consider one world 'real', then all other now worlds of all other 'moving' systems are also to accepted as 'real'. Therefore: all events of spacetime are 'real', or none is 'real'.
Every day I find it mindboggling that this is so difficult to understand by people juggling with Einstein's formulas. Relativity of simultaneous events is so easy, but apparently for many a too great mental step to take...?
I have not read every post of bobc2, but I think bob took that step.
bobc2
#71
Jul10-12, 07:40 AM
P: 848
Quote Quote by Vandam View Post
4D spacetime consists of events. Events are the buiding blocks, permanantly available to be part of a 'now'world. A 'now' world is your world at a specific point in time.
How one's worldline runs through spacetime determines which events out of total spacetime you will select as being 'simultaneous'. Our 3D world is a construction (made by ourselves) of a limited collection of in spacetime permanently available events. This collection is your world during a split second in your life. In spacetime there are no 'simultaneous' events as such, because 'simultaneity' is something we stick onto the events that we consider happening the same time. Other people will put the simultaneity sticker to oher events.
Whether a world at a specific point in time (= per definition made of simultaneous events) is 'physical' or 'real' is not that important (this gets philosophical), BUT if you consider one world 'real', then all other now worlds of all other 'moving' systems are also to accepted as 'real'. Therefore: all events of spacetime are 'real', or none is 'real'.
Every day I find it mindboggling that this is so difficult to understand by people juggling with Einstein's formulas. Relativity of simultaneous events is so easy, but apparently for many a too great mental step to take...?
I have not read every post of bobc2, but I think bob took that step.
A very nice and efficient summary of the situation, Vandam.
DaleSpam
#72
Jul10-12, 08:11 AM
Mentor
P: 16,947
Quote Quote by Vandam View Post
Every day I find it mindboggling that this is so difficult to understand by people juggling with Einstein's formulas. Relativity of simultaneous events is so easy, but apparently for many a too great mental step to take...?
Translation: "I have an untestable philosophical position that I have good reasons for liking. Therefore everyone who doesn't like it as strongly as I do must be mentally deficient."


Register to reply

Related Discussions
Accelerating Universe Expansionís Implications? (laymanís questions) Cosmology 6
Confused about implications of flat universe Cosmology 9
Block Universe General Discussion 2
Block Universe / Frozen Universe / Block Time Cosmology 1
What is gravity and what implications does it have for the future of the universe Special & General Relativity 2