Dimension Interaction

 
Now that you say that, kind of seems like it. The whole 'empty space' thing I think is going to always cause problems though. I see empty space like I see air. If you and I were talking face to face in clean air, it'd appear to be nothing between us.. but it's just nothing we can really observe. So to me, space will always be something.. just something that appears to be nothing to us, for the moment. As our technology advances, we'll probably find a way to observe it.. but as our space travel advances, we'll probably find new pockets of "empty" space to make known as well.

 

Yes, since by definition space that is devoid of matter and fields (fermions and bosons) is empty. Of course that does not mean such space does not have properties (such an intrinsic energy density), but that does not detract from its emptiness.

 
In exactly what way does quantum entanglement suggest space is an illusion? Do you have any experiments to point to that even suggest entanglement has any measurable effects on space?
 

 
In what way is space not empty? If you remove all charges, currents, matter, and fields from a region of space, what is left? Now, if you're talking about the popular notion of "virtual particles", then understand that it is nothing more than a mathematical tool to understand the dynamics of a Feynman diagram. If one can formulate a non-perturbative quantum field theory, then one can dispense with virtual particles concept entirely. Landau-Ginzburg theory is a fine example of a non-perturbative QFT.

If you are talking about quantum fields, you would be correct. But such fields are only measurable by their excitations (i.e particles). If a given space is devoid of such excitations, then (from the approach of an experimentalist or a practical theoretician) it is meaningless to talk about the contribution of such fields or their presence.

 
This is patently false! All Casimir demonstrated is that if you bring two tiny plates close together, certain electromagnetic modes will be excluded while others won't, and this difference results in an inward pressure causing the plates to draw into each other. The zero-point energy phenomenon is an idea that results directly from standard quantum theory and is independent of the Casimir effect.

 

 
That is assuming you can.. we've not been able to recreate a state like that. We can create vacuums, but all a vacuum is.. is devoid of matter. The vacuum of space is just that, devoid of matter.. but still full of energies and currents and charges and fields. Even if we could artificially recreate a state that is complete empty of all charges, currents, matter, fields, energy, and anything else you'd want to throw in there.. that doesn't mean it can naturally happen on it's own. It's like if we recreate abiogenesis in the lab.. that doesn't mean how we did it is how it happened on Earth billions of years ago. Now if some mad scientist can create a state completely empty of all energies and currents and fields, hopefully without creating a black hole that consumes Earth in the process.. then I will believe that it is a more plausible possibility that a region of space can naturally be empty of all energy, all charges, all fields, all everything. Til then, it appears that empty space is actually not empty of everything.. and possibly never will be.

 

Your contention seems to be one that is experimental in nature rather than to deal with fundamental physics. I agree with you, that we cannot experimentally create a true vacuum in the sense of removing all matter and fields, but we can create good approximations of a vacuum and observe regions of space that are very close to being a true vacuum (intergalactic space fits the bill, with something like a hydrogen atom per cubic meter), and it behaves in a way that is practically indistinguishable from a true vacuum. Also, just because we cannot recreate or observe a true vacuum (in the absolute sense), does not mean we can't make definitive statements and subtract the noise from the data. If that was the case, then no science could ever be done.

 

Curious, if you accept the zero point energy, would that not contradict your admission under question? Also, simply because there are no particles to measure the fields effects doesnt therefore mean the field is absent.

Btw you are right about Casimir effect.

Also, do fields give rise to matter or vice versa?

- oni, if we are derailing your thread lmk and ill shut up ;-)

 

 
No.. the fundamental physics states, as you agreed, that we cannot create a true vacuum like you are talking about. So a region of space that is completely empty of EVERYTHING is experimental, theoretical. It's not a theory that we haven't been able to create a state that is completely empty of everything.. cause we haven't. The regions of space that are close to being a true vacuum aren't actually close to being a true vacuum cause as of now, we don't even know if a true vacuum can exist. Those regions of space are what we refer to as dark energy.. meaning that it is energy, just energy that is currently dark to us.. meaning there is something there and unknown aside from it's effect on the universe. Sure, if you want to make a definitive claim even though we don't know if an absolute vacuum can even exist, have at it.. but being that you know we cannot recreate or observe a true vacuum, you also know that all you're left with is math backing up your theory.. right? Then understand "empty space" is nothing more than a mathematical tool to do science with.

 

Editted

 

 
No, because zero-point energy is a property of empty space. It follows directly from the energy-time uncertainty principle which requires that empty space must have a ground-state energy. Again, this does not at all detract from space being empty.

True, but science is concerned with only measurable quantities. A field that cannot be measured might as well not exist and is a philosophical question, not a physical one.

This is a very good question. To give a simplified answer, in the classical limit (i.e classical field theory), the fields are created by matter and its interactions. In quantum field theory, however, matter is actually treated as a special kind of field in and of itself.
 

Let's stop here. Nothing in fundamental physics prohibits the existence of a true vacuum, and this is more of the result of the 2nd law of thermodynamics (which is not a fundamental law of physics, contrary to popular notions) which doesn't allow a vacuum with zero entropy.
 

You are contradicting yourself. For a fact a true vacuum cannot exist in the universe, but again this is due to the emergent laws of thermodynamics rather than anything fundamental to the actual structure of the universe (such as, for example, the conservation of angular momentum, or the constancy of the speed of light in all inertial reference frames).

I'm sorry, but this is just plain wrong. The 'Dark' energy, as it is currently understood in the standard model of cosmology, permeates all of space. It is an intrinsic property of space it self, and the term "dark energy" is a misnomer as it is more of a pressure than an actual energy density. A perfect vacuum can still have this intrinsic property and not detract at all from its emptiness.
 

Except we are not debating that here. The initial debate was about a gedanken experiment where if we removed all of the currents, the matter, and the fields, if the resulting space would still be empty? Now, you're absolutely right that such spaces are mathematical constructions that only exist on the blackboard, however such constructions can teach us a lot about the universe we live in. Virtual particles, for example, are another type of construction. You can't do perturbative QFT without them, but there are no physical eigenstates for virtual particles.

 

The question then is, what is zero poiny energy? Because our disagreement was that 'empty space' is actually devoid of matter and fields. If ZPE exists as neither a field nor matter, Houston!

That is not completely true unless you reject theoretical physics as metaphysics. I'd also say its a bit anthropocentric of you to say 'a field that cannot be measured mighy as well not exist'. We cannot directly measure radiation at the Planck length or smaller, yet if radiation actually exists at this theoretical scale, even thought we cannot measure it, it very much matters (incidental pun).

So in QED the field preceeds/gives rise to perceived matter? I know you kind of touched on this, but what then of virtual particles? If the concept actually applies to physical reality then it is also supposed that there are untold numbers of virtual particles per given volume, to the point where it would be incorrect to say its empty. Sure their existence is RELATIVELY brief when observed from our macro scale, but so is our existence on a universal scale, yet it would also be incorrect to say the universe is devoid of humans because they pop in and out of existence too fast.

Food for thought anyway. Interesting and stimulating discussion and i appreciate your poise.

 

P.s. in regards to your comment about ZPE being a property of empty space (as you said devoid of field and matter) but if energy can be converted to and from matter, how can an all pervading ZPE be considered empty?

From wiki

" Vacuum energy is the zero-point energy of all the fields in space, which in the Standard Model includes the
electromagnetic field, other gauge fields, fermionic fields, and the Higgs field ."

So you take away the field you take away the ZPE, you arent even left with space, you have a literal NOthing. Not empty space, but NO space NO thing NO time.

Feel free to correct me where im wrong (which is a liberty you've endulged previously anyway).

 

 
Umm.. dark energy is unknown to us, so therefore you can't claim to know what it is. Sure, it is an intrinsic part of the universe.. but what it is is still unknown to us. We know that it is something.. just don't know what that something is.. but don't take my word for it, take NASA's: http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/

 
There is no misnomer to dark energy.. because we don't know what dark energy is. If you think you cracked it and know that it is just a pressure that isn't caused by an unknown energy, then maybe you should tell NASA and everyone else working on figuring out the universe?
 

 
No, this whole thing started when you said empty space is not a misnomer.. which it is, because it's not actually empty. You're the one who brought in a hypothetical experiment just to combat empty space being a misnomer. Which I don't understand because you've even said that such a space only exists as a mathematical concept.. so you seem like you should know that empty space isn't actually empty and therefor the term "empty space" is a misnomer. So I am not sure why you are even dragging this out.. cause based on what you've said, you should know that there is no such thing as empty space in the universe. If you know that, then you know the 'empty' part of space isn't truly empty.
 
Notice I never said to not use empty space as if it weren't empty.. I even said that it is a mathematical tool, just like virtual particles.. and dark energy. I am just confused as to why you are arguing so much against the whole "empty" space thing when even you seem to know that there is no such thing as truly empty space. If you want to go about it as a thought experiment (I hope you're German and didn't just try to look fancy by using gedanken) then sure.. truly empty space exists as a thought experiment. Seeing as it only exists in our thoughts.. it doesn't change the fact that empty space in the universe is a misnomer.

 

the fact that something can happen instantly over a long distance suggests that distance might not actually be there.

What we percieve as time and space is a mental construct used to make sense of energy interactions

-yuri

 

 
I think the problem arises because you are interpreting the term "energy" in the classical sense. Let's return to classical electrodynamics (ced). In ced, the energy density u that is stored in an EM field is given by the sum of the electric and magnetic field components. Now, this energy density is a real energy that you can "get back" to do work.
 
The zero-point energy is not in any way like this. It is a consequence of quantum laws that forces space to have a lowest non-zero energy state. It is not something you can harness to do any useful work, unlike the previous case with EM fields, and hence it is not accurate to look at it as energy stored in the vacuum but rather an intrinsic property of the vacuum it self. Think about it in the same sense that matter has the intrinsic property of inertia. Now, does that necessarily mean that matter must always be in a state of definite momentum?
 
 

Good contention. Allow me to clarify. What I meant earlier was something that cannot be fundamentally studied by its nature, not something that cannot be tested because our detectors are too primitive. In principle, there is nothing that stops us from doing physics at the Planck scale other than engineering and experimental challenges. However, something that cannot be measured or lacks repeatability is no longer part of the realm of science, but rather philosophy. Alder's Razor is a good principle to have in mind, "If something cannot be settled by experiment then it is not worthy of debate".
 
For example, in quantum mechanics, there are no definite position and momentum eigenstates (corresponding to a continuous spectra) for a free particle, and hence every time you attempt to measure either the position or momentum of the particle, the wave function will shortly thereafter change and a new measurement of either the position or momentum would yield a different value. Therefore, it becomes meaningless from a scientific perspective to talk about the position or momentum of the particle in any definitive way.
 

In QED, matter it self takes the form of a field. As for virtual particles, they are nothing more than a mathematical artifact of a perturbation theory. To help drive this point home, let's return to the classical case. Consider an EM wave propagating along the z-axis, its electric field (circularly polarized) is written in complex form. Now, does this mean that the real field component of the wave is complex (in the mathematical sense)? No, it's nothing more than mathematical convenience.

And where exactly did I claim to know what it is? Please don't put words in my mouth. I never claimed to know the true nature of the "dark energy". However, what I was saying is based on the fact we can measure the effects of the dark energy and the most accepted empirical understanding of the dark energy is as a cosmological constant. This does not mean we understand what the dark energy is at a fundamental level, but that our best guess of it as a cosmological constant in the Lambda-CDM model fits nicely with the observational data and is the most widely accepted.
 
If you want to know more about this matter beyond the simplified fluff propagated in popular science, I suggest you read this fantastic paper posted on arxiv: The cosmological constant and Dark Energy.
 

By that logic, me calling the "dark energy" dark gravity, or dark momentum, or dark acceleration? After all, we don't know what it is, so anything goes!

Can you please stop putting words in my mouth? And you also seem to be completely misinterpreting what I am saying. Dark energy has a positive energy density, and a negative pressure. It is NOT a form of stored energy in the vacuum of space, which seems to be what you think it is. This picture is the most consistent with all the observational data and the most accepted by the scientific community at large. I highly suggest you read that paper I linked so you can educate yourself on this topic.
 

OK, then please answer the question: If you remove all fields and matter from space, then what is left except empty space?
 

I guess wasn't I being clear enough. Empty space (in the absolute fundamental and abstract sense) is perfectly empty and not a misnomer. What I'm trying to combat here are popular notions that it is not, and that at a fundamental level there are virtual particles popping in and out of existence. This is not at all the correct way to looking at an empty vacuum.

Then I think this is just a great big misunderstanding. We seem to be in perfect agreement as far as the true nature of empty space is concerned.

 

 
This is where the confusion must be.. cause yes, if you did remove everything.. you would be left with nothing, but so far.. removing everything is ONLY a thought experiment. The idea of empty space in the universe is not that.. because the empty space of the universe is made up of something, we just don't know what that something is. I'm not talking about a thought experiment, you are.. I am talking about the reality of the universe. Out there, the vacuum of space isn't devoid of everything.. it is only devoid of matter.
 
Not once was I ever talking about a thought experiment in terms of empty space.. and I am not going to say "ok.. just because you can create a thought experiment about truly empty space means there is such a thing as truly empty space" cause if I validate your theory based on a thought, then I'd have to validate all theories based on a thought.
 
So far, it's not physically possible to removed EVERYTHING from space.. you can only do so in thought experiments. That why, in terms of the reality of empty space.. it's not actually empty, which would make.. it.. a.. misnomer..
 

 
If you'd want to.. go for it, but not much of a point. The dark in dark energy isn't so much because it is on a level that can't really interact with light.. but because we can't directly observe it. The dark in dark energy is like the dark in the dark side of the moon.. which isn't actually dark, it get's light plenty, but we can't directly observe it from Earth. Being that is it unknown as to what it is actually made of.. you could technically make up anything you'd like in the meantime.. but like I said, wouldn't really be a point.

 

Lets talk about that. I am only broadly and superficially educated on this stuff. I love science, especially physics, but the more i look into it the more i have come to believe its a lot of smoke and mirrors.

I would say yes to your question. Velocity is only relatively meaningful, so subracting velocity, mass = momentum. So definite momentum IMO is spin, velocity is subjective on frame of reference.

 

Dimensions aren't places. This is not soemthinf any scientist believe

M theory dimensions are true dimensions. Like up down left right.

There are jjust more than the 4 possibilities we can percieve

It is impossible for things to exist in only one dimensions and not interact with things in other dimensions, because its still the same world.

-yuri

 

We are always constantly shifting through dimensions and parallel universes.


We are only able to notice this once we reach higher levels of awareness ourselves.

 

We are in the dimensions we are designed to inhabit. I believe that the discovery of these other dimensions could expose our fragile bodies to pressures and energy unimaginable. Just me though ??!!!

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