Sharing the same "now"

[asprung]

Why is "now" not absolute ? It is the essence of exsistance.

[iNow]

No, it's not. It is an abstract concept with no bearing on the universe. Once you realize this, you will have an easier time accepting the responses of others regarding temporal relativity.

 

Now is a perceptual idea, not a fact of the universe.

 

 

I've said this before... I'm sympathetic to your views, but it's philosophy, not science. Try not to conflate the two, as it will only lead you to further confusion.

[asprung]

I am confused. If the universe only exists "now" what could be more absolute?

[iNow]

I am confused. If the universe only exists "now" what could be more absolute?

 

Let's start there. What proof do you have that the "universe only exists now?" What are the parameters of this temporal coordinate, "now?"

 

 

You see "now" as some infinite, and all eveloping entity, right?

You see "now" as an ever expanding moment that encompasses all futures and all pasts all at the same time, right?

You see "now" as the absolute consistent thread through the entire universe and through all epochs, right?

 

I understand. I've had these thoughts myself, but it's philosophy, not fact or science, and especially not relativity.

 

 

I'll give you a hint that I realized... It's only absolute within your own perception... within your own mind. After that, it's no longer absolute.

[NowThatWeKnow]

I see "now" as a single point in time if I could be everywhere in the universe at once. The clocks on Earth and the clocks on the GPS satellites may run at different speeds but they do share a simultaneous point in time. With enough information you could compare your "now" to any locations "now" in the universe. Therefore a universal absolute "now" is possible. What is the flaw in my logic?

[iNow]

The clocks on Earth and the clocks on the GPS satellites may run at different speeds but they do share a simultaneous point in time.

How so? Time is inseparably coupled with space. The earth and the GPS satellites occupy different points in space, ergo experience different time.

 

Like I said to asprung, the only place "now" is consistent (or absolute) is in your mind... or, if you'd prefer, in your own reference frame.

 

 

With enough information you could compare your "now" to any locations "now" in the universe.

Again, this seems to assume a decoupled spacetime.

 

 

Therefore a universal absolute "now" is possible. What is the flaw in my logic?

It was in your premises.

[NowThatWeKnow]

It was in your premises.

 

What you are saying is two people on different floors of a building can not share the same "now". Einstein Online defines "now" and I interpret it to say two events in two different frames can be simultaneous. Isn't that what you understand from the quote below?

 

As posted earlier in this thread.

 

The definition of "now"

http://www.einstein-online.info/en/spotlights/Now/index.htmll

 

"two events are simultaneous if and only if they can be seen on the same photograph, taken with a double camera placed exactly in the middle between their locations."

Edited February 25, 2009 by swansont
fix url

[swansont]

The definition of "now"

http://www.einstein-online.info/en/spotlights/Now/index.htmll

 

"two events are simultaneous if and only if they can be seen on the same photograph, taken with a double camera placed exactly in the middle between their locations."

 

How does that reconcile with "a universal absolute "now" is possible." ?

 

——

 

But, I think that the original context of this discussion was the twins paradox, where the second twin has returned, and the twins are co-located. They will both observe an event, and the signal will reach them simultaneously, i.e. "now". IOW, if they each sent out a flash of light when they observed the event, the flashes (the sources being being co-located) would be simultaneous in anyone's frame. However, they will disagree on when the event occurred, according to their own clocks.

 

Why is that a problem?

[NowThatWeKnow]

How does that reconcile with "a universal absolute "now" is possible." ?

 

An infinite number of cameras would show any location would share a point in time with any other location.

 

Maybe my thoughts are not coming out clear but I do not disagree with what you are saying or have been saying. Actually, I am not sure how or why I got back into this thread.

[iNow]

An infinite number of cameras would show any location would share a point in time with any other location.

 

But an infinite number of cameras won't result the output of a single photograph (to use the definition you provided from einstein online).

[asprung]

If we could quantatize "now" and the progression of "now" we might have a better understanding of the universe.

[iNow]

Like the tip of an ever enlarging cone? Like the breaking edge of the collapsing wave function? What do you mean? Like what?

[asprung]

I see the universe as a single ever progressing "now". You dont. What do you see it as?

[john5746]

I see the universe as a single ever progressing "now". You dont. What do you see it as?

 

I'm always seeing the past.

[iNow]

I see the universe as a single ever progressing "now". You dont. What do you see it as?

 

I never said that I don't. I tend to agree with much of your sentiment. However, did you realize how you began your sentence with the words "I see..."? By doing so, you implicitly acknowledge that you are only speaking from your own reference frame. That's the point. Your now and my now are not the same, ergo... not universal.

 

The issue is in perception, in your conscious existence, not the universe itself... Or, at the very least, we have no evidence to support the idea that the universe shares some absolute thing we call "now."

 

It's philosophy, and it's fun to play around and explore, but it's not science and it doesn't help our understanding or ability to manipulate the universe for our own gain. That's where relativity and QM come it...

[asprung]

You are not seeing the past. You are seeing its history "now".

---

Merged post follows:

Consecutive posts merged

Maybe its a starting pont to put relativity and QM together.

[swansont]

I see the universe as a single ever progressing "now". You dont. What do you see it as?

 

From what I can tell of how you are using "now," the universe does not behave the way you see it.

[NowThatWeKnow]

But an infinite number of cameras won't result the output of a single photograph (to use the definition you provided from einstein online).

 

You don't need a single photograph to know that every location will share a point in time with any other location. Einstein Online just shows that events at any two locations can be simultaneous and they call that "now".

[Martin]

...

Maybe its a starting pont to put relativity and QM together.

 

Asprung, I'm going to say something that may sound dismissive even condescending but I don't mean it that way.

Your problem is not directly about being right or wrong---the problem of time in physics is still unresolved (read Rovelli's essay, I'll get a link)---your problem with the informed people on this board is being naive.

 

What you need to watch out for, and remedy, is naive over-interpretation of what you hear, and reckless leaps of inference.

 

But still, allowing for that, I like the independent imaginative way you think and hope you continue with the good aspects of that.

 

As you may have heard, cosmologists use a rough time scale called universal time for some limited purposes. There is an idea of universe-wide "now" in cosmology which is essential to defining the main formulas, equations, the conventional model.

 

Just because in some area of research they find a universal timescale useful for certain purposes doesn't mean you can over-interpret that and advocate absolute time in a broader context. That is taking a naive leap. Science is a community. If you want to talk with members of the community you have to stay within bounds. The proper stance about time is to reserve judgment. There are too many unresolved issues about time.

 

Also I think you need to learn more. Thanks for listening to a fellow non-expert in these matters.

[swansont]

You don't need a single photograph to know that every location will share a point in time with any other location. Einstein Online just shows that events at any two locations can be simultaneous and they call that "now".

 

But they will not be simultaneous at all points in all reference frames.

[asprung]

Where and when might the universe exsit other than "now"? It seems that there is a problem equating the progression of "now" with time. As I see the progression of "now" It is a demension (other than distance) that occurs between events.

[iNow]

Where and when might the universe exsit other than "now"?

 

Relative to what?

[swansont]

Where and when might the universe exsit other than "now"?

 

That's just it — it's a tautology. It's always now. As such, "now" adds no information to the discussion. There's no physics in it.

 

 

And we've been over this ground before

[asprung]

It may allways be "now". But "now"progressed from former "nows". Why is it not physics? It presents a view of the universe and its ageing.

[Martin]

It may allways be "now". But "now"progressed from former "nows". Why is it not physics? It presents a view of the universe and its ageing.

 

Einstein worried about this question. It bothered him that conventional physics as we know it (and as he knew it back in the 1950s) was unable to define "now".

 

There is a record of a conversation he had with the philosopher Carnap about this.

 

Asprung you have got to stop and educate yourself a little and get less naive.

You have an interesting idea with some validity. So you need to read stuff by established scientists that agrees in some sense with you.

 

For example here is a video lecture at the Perimeter Institute in Canada in which the hypothesis of the reality of time as a succession of present moments (the reality of "nows") is explored by a physicist.

http://pirsa.org/08100049/

What I do is download the MP3 audio and have it ready to start. Then I click on "windows presentation" which takes a minute or so to warm up and as soon as the video starts I quickly start audio, so they are in approximate synch. For some reason the windows presentation no longer has its own synched sound.

The Einstein-Carnap conversation is quoted in this talk. The slides are downloadable as PDF. It's controversial but quite interesting.

 

The issue of time in physics has not been settled and the prevailing concepts of time are constantly being challenged. A prominent foundation that supports scientific research has set up an essay contest asking about The Nature of Time. Some prominent scientists have submitted essays. Here is one for example that says that to get a good quantum gravity model, the model may have to have no time axis at all, its world may have to be only "now" in a sense.

http://www.fqxi.org/data/essay-contest-files/Rovelli_Time.pdf

The essay may be shocking but it could win the contest. The guy is a leader. Even his rivals, the string theorists, invited him to give a plenary talk to their big annual conference last year, Strings 2008. A talk describing his quantum gravity research program and results to date. The ideas may be shocking but the guy is recognized world-class. Not a fringe or a crackpot.

 

What can be gained by your arguing for your position in isolation, without reading what other people have had to say about the same issues?

 

I don't like seeing you do this. If you argue in ignorance you will just get your bum kicked and nothing will be accomplished.

Edited February 27, 2009 by Martin