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Author  Topic: What is "the fabric" of spacetime?  
randman Suspended Member (Idle past 4134 days) Posts: 6367 Joined: 
Catholic, it's a little deeper than that. Cells actually consist of physical properties. What cavediver is saying when he says it consists of "nothing" is that it consists of no matter or energy (defined by physics). Personally, I question stating a field has no energy even if it is a field that has no matter but I recognize what that's problematic for physics (definition of energy must contain matter).
But whatever this consists of, it does give rise to matter. Imo, this is worth thinking about. My word for "nothing" is "immaterial." It's not nothing because we see it's effects and it can be described mathematically, but since it has no matter, it is an immaterial something.


randman Suspended Member (Idle past 4134 days) Posts: 6367 Joined: 
Emergent properties from one physical system to another so that the sum is greater than the parts is worth discussing. It's not really the thread topic.
But what we are talking about is that physical existence (matter and energy) stems from a nonphysical existence or thing. Edited by randman, : No reason given.


New Cat's Eye Inactive Member 
Actually, I think it is deeper than the depth that you think it is.
If energy/matter is an emergent property of the field, then what's the problem?
Think of it as energy being an emergent property of a quantum field. Then the field, itself, doesn't need to have energy.
Immaterial, to me, means that it just lacks mass. Light is immaterial, but it isn't nothing.
Well, if you want to use the word 'immaterial', then go right ahead.


randman Suspended Member (Idle past 4134 days) Posts: 6367 Joined: 
There is no problem. Just pointing out the "field" as you say has no energy or matter. Energy and matter originate from an immaterial state.
Light is not immaterial. Maybe you aren't getting the concept here?


New Cat's Eye Inactive Member 
So what?
Maybe not. Please enlighten me.


randman Suspended Member (Idle past 4134 days) Posts: 6367 Joined: 
Light consists of photons. Photons are particles and have energy. We were talking of what gives rise to particles, mass and energy, not emergent properties after that occurs.


New Cat's Eye Inactive Member 
What I said in Message 18 is: quote: What I was saying is that light doesn't have (rest) mass so by some definitions it can be called immaterial. Its a small point, but I think that is a better definition than immaterial means "nothing". quote:
And what gives rise to particles, mass and energy is not made up of particles, mass and energy. They come from quantum fields. Like I was originally saying, you could think of particles, mass and energy as emergent properties of the quantum field. My position is both veracious and consistent, so can we move forward now? Where we left off was me asking: quote:


Calypso Junior Member (Idle past 4391 days) Posts: 28 Joined: 
Hmm you lost me there I think. Objects that we know from mathematics? Is not mathematics just the language we use to describe what we see out in the universe? So I would think we know these objects from mathematics because we invented mathematics to describe what we see happening in the real world. Correct me if I'm wrong. Are you asking why they fit a mathematical model so well? Did we not come up with that mathematical model to fit our observations rather than the other way around? Or did I misunderstand what you meant by that question? If so please expound on it if you could? It intrigues me and probably because I think I do not understand it, or what you meant by it. Also when you said "They're not made of anything  they are the underlying reality  everything else is made from" My question to that would be so mass is warping nothing? How can you warp nothing? I'm having a hard time understanding this concept. I would think if there is nothing there, then there is nothing to be warped or deformed. As far as I see it, mass is warping something is it not?


fallacycop Member (Idle past 4756 days) Posts: 692 From: FortalezaCE Brazil Joined: 
mass warps space


Chiroptera Inactive Member 
To be more precise, spacetime is a manifold  that is, it is a four dimensional object that has a certain shape. The fact that the shape isn't completely flat is what we call "warped". This "warping" of spacetime  the fact that in places it is very much not flat  is what we experience as "mass".
Mass doesn't warp spacetime. Rather, mass is the warps in spacetime. If I had a million dollars, I'd buy you a monkey. Haven't you always wanted a monkey?  The Barenaked Ladies


randman Suspended Member (Idle past 4134 days) Posts: 6367 Joined: 
So what in your view does the quantum field consist of?
Cavediver makes an interesting statement, namely that energy and mass arise from something that has no energy and mass. Photons have energy. Photons arise from this something other. What is it?


Calypso Junior Member (Idle past 4391 days) Posts: 28 Joined: 
I've heard it said like this: Mass tells space how to curve, space tells mass how to move, Or something like that. I'm paraphrasing but this would mean mass does warp space. So is this not correct?


New Cat's Eye Inactive Member 
I don't think that it "consists" of "stuff". It is prestuffs. It is a very complicated field and I don't feel capable of explaining it to you. How much do you know about fields? Somebody can't just come in here and say: "The quantum field consists of blah blah blah...." You have to understand the math and some pretty difficult concepts to begin to understand, or spout, the descriptions of what a quantum field is.


New Cat's Eye Inactive Member 
A tidal wave is a warp in the ocean, so does the ocean warp waves?


Chiroptera Inactive Member 
This is an interesting question.
Disclaimer: I do not have any real experience with GR. From the physics side of my education, GR requires a knowledge of differential geometry, which is not part of the standard curriculum for physics students even at the graduate level. It is mostly those students who are specializing in GR who end up studying it. On the math side, I did take a course in differential geometry. But I never really got an intuitive feel for what a nonpositive definite metric "looks like" (I can "visualize" an nmanifold with a positive definite metric), nor did I ever see physics applications. So, my "explanation" is going to consist of what I understand from the math side. Manifolds automatically come already curved. In fact, it is how the manifolds are curved that distinguishes them. The curvature is basically the shape. The only significant difference between a sphere and an oblate ellipsoid is that the curvatures are different. If I hand you a sphere, it is already curved  that is what makes it a sphere. So, when our universe is modelled by a Lorentzian 4manifold, it has to come with some shape. In the physical GR model, mass density is a parameter (or one of several parameters) that is part of the mathematical equations that describe the curvature. Now the interesting question is: is there some physical quality called mass that forces the otherwise flat manifold to curve? Or is does the manifold already come curved, and our experience of mass simply how we percieve this curvature? This becomes a metaphysical question, about how exactly we are going to interpret the mathematical equations to make sense of what we actually observe. But in the end that's all we have: the mathematical models, a way of interpreting the results of calculations in terms of potential observations, and some measure of how close the potential observations match up with our actual observations. The actual ontological nature of the universe is, I suspect, beyond what science can really answer. If I had a million dollars, I'd buy you a monkey. Haven't you always wanted a monkey?  The Barenaked Ladies



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