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Author Topic:   What is "the fabric" of space-time?
Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 58 of 327 (458678)
03-01-2008 2:48 PM
Reply to: Message 55 by randman
03-01-2008 2:07 PM


randman writes:

My understanding is that dark energy and dark matter are somehow related, but it's still fairly theoritical. It will be interesting to see how it pans out.

This might describe the view of some cosmologists, but in the view of most they are separate and distinct concepts. While we've given them names, we do not yet know the nature of either.

Dark energy is the name given to the driving force behind the accelerating expansion of the universe.

Dark matter is the name given to the purported source of extra gravity that keeps rotating galaxies from flying apart. Proposals for the identity of dark matter are MACHOS (Massive Astrophysical Compact Halo Objects) and WIMPS (Weakly Interactive Massive Particles). WIMPS seem to be the preferred alternative at present.

Most likely, it is spiritual (non-physical) energy.

You might want to consider the advisability of applying the term non-physical to something so intensely physical that it is driving the entire universe toward oblivion.

--Percy


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 Message 55 by randman, posted 03-01-2008 2:07 PM randman has replied

Replies to this message:
 Message 61 by randman, posted 03-01-2008 6:11 PM Percy has replied

  
Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 67 of 327 (458742)
03-01-2008 8:30 PM
Reply to: Message 61 by randman
03-01-2008 6:11 PM


randman writes:

You might want to consider the advisability of applying the term non-physical to something so intensely physical that it is driving the entire universe toward oblivion.

It's intensely physical but has no energy or mass?

Maybe you thought I was referring to dark energy instead of the fundamentals of what gives rise to space-time?

You kept referring to a field, and at heart all phenomena in the universe, including the dark energy your post opened with, are just perturbations of the quantum field.

About "what gives rise to space-time," which is probably the same question as, "Why something instead of nothing?", Cavediver usually expresses this more clearly, and he'll correct me if I'm wrong, but if the quantum field is made up of "something" or "somethings", we don't know what that is at present. Amongst the scientists working at the frontiers of cosmology I'm sure you'll find some interesting speculations, but as far as scientific evidence for what comprises space/time, I don't think there is anything that points in any particular direction right now, or even that says it must be made up of anything.

I don't see the point of arguing with Cavediver about what he meant. He's the one that would know, and I don't think he would purposefully lead you to erroneous conclusions.

--Percy


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Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 136 of 327 (459287)
03-05-2008 4:28 PM
Reply to: Message 133 by randman
03-05-2008 1:25 PM


randman writes:

But I think rather than clouding the issue with labels since under your definition of physical, all spiritual things are actually physical too...

I don't think anyone in this thread is arguing for or against the spiritual. That's not the topic, and this is a science thread anyway. If you want to argue in favor of giving the spiritual scientific status you should probably propose a new thread for Is It Science?.

If space and time are derived properties as well as energy and mass of the field, then absent the derived properties, what does this field consist of?

I think we all understand that this seems like a meaningful question to you, but the field is fundamental. This is nothing more fundamental for it to "consist of".

Btw, Cavediver said he describes it "as mathematics" and so under your definition coupled with his comment, math itself is a physical thing.

Cavediver was not arguing that mathematics is a physical thing. He's was making the same point PaulK has been making to you, that the quantum field is the most fundamental physical thing we know of.

When a physicist or cosmologist is speaking for a lay audience he may give way to saying things like, "Entanglement operates outside of space and time," but in such cases he's only referring to the layperson's classical understanding of space and time. Entanglement does not operate outside of space/time. After all, entanglement was predicted by the mathematics of quantum theory, our current most fundamental model of space/time.

--Percy

Edited by Percy, : Grammar.


This message is a reply to:
 Message 133 by randman, posted 03-05-2008 1:25 PM randman has replied

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 Message 138 by randman, posted 03-05-2008 5:20 PM Percy has replied

  
Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 143 of 327 (459300)
03-05-2008 5:56 PM
Reply to: Message 138 by randman
03-05-2008 5:20 PM


randman writes:

Just because something is fundamental does not mean it doesn't consist of anything.

In this context we're using the term fundamental to mean that it is not made up of anything that's more, uh, fundamental. Our present understanding is that the quantum field cannot be deconstructed into more fundamental components. That's why we call it fundamental.

What properties normally associated with physical or material things does the quantum field, as you put it, have?

If you mean classical physical properties, the quantum field doesn't possess such qualities. The quantum world is not at all like the classical world. That's why it's so difficult to understand, because the physical analogs we're so used to using don't apply there. Maybe it was Feynman who said something like, "The quantum world is not only stranger than you think, it's stranger than you can think."

Just because energy, matter, mass and space are derived from it does not mean it consists of energy, matter, mass and space...

Nobody is making this claim. What we experience as our macro world reality is actually just expressions of the quantum field.

So it does not consist or behave in a manner congruent with the normal limitations of physical things.

No one is saying it is or does. The quantum world is not the physical world of everyday experience writ in miniature. It's something completely different. What we experience in everyday life as very much physical matter and energy is actually just ripples in the quantum field. That's what the physical actually is.

It exhibits instant action at a distance regardless of time and space, for example. If you want to call that a mechanistic or physical action, fine, but it certainly defies what we know about physical things in space and time.

No one is saying that entanglement is a mechanistic or physical action. We're carefully refraining from drawing such analogies. In fact, we're trying to argue that such analogies can be very misleading when trying to think at the quantum level, and we're trying to encourage you to abandon them.

Zeilinger says the process is outside space and time. He's not being superfluous there.

He's talking for laypeople trying to give them a sense of the strangeness of the quantum world. You shouldn't be trying to draw quantum level conclusions from his classical level analogies.

Zeilinger isn't the only physicist or cosmologist who does this, by the way. Any such people constructing popularizations of quantum theory for unscientific laypeople will be doing this. It's why those who draw quantum connections to the mystical have such an easy time quoting scientists in their support.

I'm sure there must exist scientific popularizations directed at more scientifically sophisticated laypeople, and you'd be much better served drawing your information from these rather than from run-of-the-mill popularizations or news accounts. Maybe someone can suggest a couple.

--Percy


This message is a reply to:
 Message 138 by randman, posted 03-05-2008 5:20 PM randman has replied

Replies to this message:
 Message 148 by randman, posted 03-05-2008 7:35 PM Percy has replied
 Message 149 by randman, posted 03-05-2008 7:38 PM Percy has replied

  
Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 159 of 327 (459327)
03-05-2008 9:27 PM
Reply to: Message 148 by randman
03-05-2008 7:35 PM


randman writes:

The quantum world is not the physical world of everyday experience writ in miniature. It's something completely different.

Isn't that exactly what I have been saying and trying to get you guys to discuss the properties which indicate it is "completely different."

I don't think that viewpoint is shared by anyone but you. To everyone else you seem to be confusing classical and quantum descriptions of reality.

You can call something "completely different" physical if you wish, but it's completely different than what is thought of as physical.

But we're not calling the quantum world physical in the classical sense. In our most accurate model to date, the quantum model, the foundation of reality is the quantum field. The objects in the macro world that appear so substantial and so real to us are actually just manifestations of the quantum field.

It's description actually fits better with what men in the past have called "spiritual"...

Well, to repeat, if you want to make the case for the "spiritual" deserving scientific status, you should probably propose a new thread.

And as has been said several times now, I think most of us would agree with you that descriptions of the quantum world directed at laypeople have a very spiritual quality to them. Gazing upon the foundation of our universe, be it at the level of the quantum field or at the macro level of star nurseries and the background radiation of the Big Bang, brings out spiritual feelings in us all. It's what makes us human. But you won't find spiritual claims in the math or the technical papers.

--Percy


This message is a reply to:
 Message 148 by randman, posted 03-05-2008 7:35 PM randman has replied

Replies to this message:
 Message 170 by randman, posted 03-09-2008 4:35 PM Percy has replied

  
Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 160 of 327 (459329)
03-05-2008 9:38 PM
Reply to: Message 149 by randman
03-05-2008 7:38 PM


randman writes:

The way I look at this discussion is I am trying to get you guys to abandon your old worldview and accept the implications and facts of QM.

Uh, okay. Meanwhile, back here on planet Earth you'll find that the views of quantum theory expressed here by Cavediver and Son Goku are pretty widely shared throughout physics and cosmological circles.

No, he's doing more than that. He's actually pointing out that entanglement is a process outside time and space because it occurs independent of space-time separation.

As I said before, entanglement does not operate outside of space/time. After all, entanglement was predicted by the mathematics of quantum theory, our current most fundamental model of space/time. How could entanglement be operating outside the theory that predicted it?

--Percy


This message is a reply to:
 Message 149 by randman, posted 03-05-2008 7:38 PM randman has replied

Replies to this message:
 Message 163 by Silent H, posted 03-05-2008 10:06 PM Percy has taken no action
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Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 162 of 327 (459331)
03-05-2008 10:01 PM
Reply to: Message 155 by randman
03-05-2008 9:00 PM


Re: Cavediver: determinism
randman replying to Cavediver writes:

You say:

Standard QM breaks causality

You needed to read on. The full context is:

cavediver in Message 154 writes:

Standard QM breaks causality because it is not relativistic. It is therefore unrealistic and cannot be used in relativistic situations, not can it explain concepts such as particle creation and annihilation. That is why relativistic QM was developed, finally becoming quantum field theory.

In other words, Standard QM is not causal, and that isn't its only shortcoming. The more accurate and useful quantum field theory *is* relativistic (special theory only, I believe) and addresses many of Standard QM's shortcomings, including the lack of causality. It is definitely not an accepted view within the field of quantum physics that causality is violated.

Son Goku's Message 119 did a great job of putting things in context vis-à-vis the various stages of progress in the development of quantum theory.

Any errors or mistakes are my own. As always on this particular topic, I defer to Cavediver and Son Goku if I've misunderstood or misexplained anything. I'm trying to help understanding, not get in the way.

--Percy


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Percy
Member
Posts: 20709
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.4


Message 173 of 327 (459742)
03-09-2008 5:13 PM
Reply to: Message 170 by randman
03-09-2008 4:35 PM


Hi Randman,

If you'd like to argue that the spiritual, in whatever way you would like to define it, should be given scientific status, I again suggest you propose a new thread.

So much of your post was off-topic diatribe that I can find nothing I can respond constructively to. If you'd like to continue discussion then I suggest you reply to one of the earlier messages, but not in the same manner you just did.

--Percy


This message is a reply to:
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