What Defines the Fabric of Time in Space?

[36grit]

What is space? it's got to be the biggest thing in the universe. I'd even go so far as to say it defines our universe from (if there are any) other universes.
but what is it?
Is it literally a fabric of time? If so then how and/or what defines the past, present, and future physically?
Are there space specialists? What would you call someone who specializes in the study of the space time fabric?

 

[Blibbler]

Oh golly, such a big question.

Space and time can't be seen as distinct as far as Relativity is concerned. According to Relativity space and time are a 4 dimensional manifold as described by Minkowksy. So, instead of having spatial dimensions x, y and z with time dimension t, Minkowsky spacetime is simply x1,x2,x3,x4; with time being whichever of those dimensions suits your frame of reference.

This doesn't help you.

The problem is that the observable universe, the Present, is a Minkowski x1,x2,x3,x4 manifold deformed by mass and energy according to Einstein's equations. However, the observable universe, the Present, is not the whole story. We also need to consider the universe at time t to include not just x1,x2,x3,x4 but also what I call the Absent - that part of the observable universe which is affected by quantum processes in dimensions very close to our universe but which form not the "real" universe but the Dirac sea of virtual particles and their antiparticle correlates.

The Absent is simply the Present from a different frame of reference. What we see as the Dirac sea in the vacuum is simply real matter in a universe whose shockwave of its own Present intersects with our own universe for a nothingth of a second. A different Present. Part of our Absent. But still part of Now.


The key word here is "vorticity". The world we see around us is a surface, a shockwave if you like, propagating through time. What we see as the present is merely the surface of the shockwave as it converts the highly entropic future into the zero entropy past. This surface appears to have the properties of a superconducting superfluid and yet we can't describe it as an ether or as anything real. We can only describe the particles that exist within it as wavelike entitities which when integrated over time look like vortex lines in a quantum superfluid such as helium 3. These wavelike entities, integrated over time, look like tubules of spacetime, fibres with a property of vorticity. They occur in different famililes, analogous to the families of vortices found in superfluid helium. Magnetic flux is an example of this superluid vorticity.


So, without getting too verbose, your problem really touches on the incompatibility of quantum mechanics and relativity. There is no aether. But what we see as the present is simply a surface between the past and the future. The rate at which a particular part of that surface migrates through time is a function of how much energy and or mass there is in its vicinity.

Hope that helped.

 

[36grit]

So, you basically saying that the space time fabric is a fabric of xyzt, influenced by a force that is absent and yet defines the present shockwave of the physical for a nothingth of a second and then becomes the past. I guess. I'll read a couple more times. It's hard to follow.

Now I'm wondering where these absent forces reside. Are they the probably future ?
are they housed by any physical entity?
does time move in a path of least resistance?
or am I way off base and confused?

 

[kgbgru]

I have always thought of space as the board that the game of life is played on. It is what we use as a refrence points to relate the elements of our reality.

 

[harrylin]

What is space? it's got to be the biggest thing in the universe. I'd even go so far as to say it defines our universe from (if there are any) other universes.
but what is it?
Is it literally a fabric of time? If so then how and/or what defines the past, present, and future physically?
Are there space specialists? What would you call someone who specializes in the study of the space time fabric?

In a nutshell: there are no "space specialists" as such. And different people mean different things with that word.

In Minkowski's world (which is most popular nowadays), for the description of events the measurement of spatial distance is interlinked with the measurement of time, and this led to the concept of a space-time or "space" of 4 dimensions; basically a mathematical space[1]. Over the years, the concept of "spacetime" has become understood as if it is itself a physical entity, and this philosophy has become associated with relativity theory.

However, in Einstein's world (at least 1920-1924), the space-time functions of general relativity reveal that a physical space exists - roughly bringing back the "ether" concept (Lorentz style)[2]. In his view then, space has properties that depend on nearby mass, and in turn it affects time keeping by clocks. That concept has become unpopular, but see next.

In the world of quantum mechanics, space is basically the same as "the vacuum" and it has physical properties - it is certainly not nothing. And if established theorems such as Bell's are correct (look up Joy Christian for a challenge), then effects can propagate instantly over large distances - in any case, much faster than light, although this cannot be directly measured. In recent years it has been argued that this implies the existence of a true (but not measurable) simultaneity in nature and that challenges the "spacetime" philosophy [3].

1. http://www.bartleby.com/173/17.html
2. http://www.tu-harburg.de/rzt/rzt/it/Ether.html
3. http://hep.princeton.edu/~mcdonald/examples/QM/hardy_prl_68_2981_92.pdf

 

[Blibbler]

A very succinct way of putting it is to say that if space is where you arrange information, time is where you re-arrange it.

We live in an informatic, numerical, computational universe. Information is the fundamental quantity of our universe and any successful grand unified theory of physics will be a grand unified theory of maths, consciousness and turbulence.

 

[Dremmer]

Space is what keeps everything from happening in the same place.

 

[brainstorm]

I was recently reading about Goethe's theory of colors and it seems that the big difference between Newton and Goethe where light and color was concerned is that Goethe thought that dark(ness) interacted with light to produce color, whereas Newton believed that white light contained all colors, which is why it could be separated into them using a prism.

I tend to think a Goethe-type perspective often comes out in discussions about space (where space it viewed as a substance similarly to Goethian darkness). Space can't really be its own thing within Newtonian physics because it doesn't consist of matter-energy. Space is to matter what a shadow is to light. So conceiving of space or spacetime as a fabric (beyond as a conceptual metaphor) seems incorrect to me.

If anything, I think space can be thought of in terms of gravitational fields extending beyond other field-forces. If strong nuclear force and gravitation were co-terminous fields, then space would not exist. It's only the fact that nuclear force condenses electrons within a denser configuration than super-particles composed of protons and electrons (i.e. atoms & molecules, etc.) that space can exist amid matter-energy.

Beyond that, how can space exist in any substantial way? It is not a force or a field of any kind.

 

[dreiter]

Well I know this isn't helpful to the conversation, but I don't really see how anyone can say they KNOW what space is. At this point all we have to explain it is an abstract mathematical construct, and even the theories describing that are not set in stone.

Just my 2c. :)

 

[franklinhu]

What is space? it's got to be the biggest thing in the universe. I'd even go so far as to say it defines our universe from (if there are any) other universes.
but what is it?
Is it literally a fabric of time? If so then how and/or what defines the past, present, and future physically?
Are there space specialists? What would you call someone who specializes in the study of the space time fabric?

It sounds like you want to know what "substance" space is made up of. Officially, it's made out of nothing as there is no 'aether'. However, they also say that space is filled with Higgs particles or virtual particles or vacuum energy. It certainly doesn't sound like 'nothing'.

It would be purely speculative to name the 'substance' of space. So for example, let us then speculate on what it could be. If nobody knows what space is made out of, let's make something up out of the blue. My favorite candidate is a positron/electron dipole combination. This means space is built out of oridinary matter positron/electron dipoles which fills all available space. I call them poselectrons. Why would be believe such a thing? Well, if we send high energy gamma rays into space, we see pair production - the generation of positrons/electrons. Where did they come from? The breaking up of the poselectron is a posisble candidate. There is also mainstream evidence of a virtual sea of positrons/electrons popping in and out of existence. But to answer your question, we need to first assign a 'substance' to space and so this is as good as any.

So, once we have our 'sea' of particles, we can then speak of time as being measured as the smallest amount of time it takes for one poselectron to move another poselectron. This would then define the smallest amount of time possible in space and would define the quanta of time as a finite and fixed amount. The notions of time are what you would think they are.

Past are interactions which have already happened. Present are the interactions which are happening the moment and the future are interactions that will happen. Nothing spectacularly interesting about this when you think of time as being mediated by a sea made out of poselectron particles. What you don't get from this picture is the ability to go back into the past or move ahead in the future. Such things are impossible in a physical model such as this.

Under this model, the universe 'ticks' like the clock in a computer with a universal speed. Effects such as time dilation can be seen as actions taking more or fewer clicks of the universal clock. So time in a real sense, time does not slow down, but only the rate of interaction between particles slows down. So a particle heading at near the speed of light, takes far more ticks to move from point A to point B than would the same particle at rest. The physical reason for this is that at high speed, a particle moving from point A to point B must go past many, many more particles than a particle at rest.

Once again, this answer is purely speculative and defies most of relativity, but I'm just trying to frame an answer that gives you a possible answer to the relation between space and time based upon a physical model. There are no official answers to this question, so I have provided one which you could basically consider 'science fiction', but provides a model you might be able to understand.

 

[36grit]

I feel like this question has at the very least spurred some imaginations. I appreciate the input and now I do have a better understanding.
Space: Distance as bands of history imprinted by photons and energy forces and occupied by mass.

One time I saw light from a pulsar bend around a large galaxie. By the time it reached Earth it looked like twin pulsars. The narrator said it was called a lenzing effect. I couldn't help but think that the light was pushed away from the galaxie by the distance history radiating from it.


Why yes, I'm a proffessor of timeology at Iguess U. :rofl:

 

[36grit]

Shear Poetry in my eyes

Oh golly, such a big question.

Space and time can't be seen as distinct as far as Relativity is concerned. According to Relativity space and time are a 4 dimensional manifold as described by Minkowksy. So, instead of having spatial dimensions x, y and z with time dimension t, Minkowsky spacetime is simply x1,x2,x3,x4; with time being whichever of those dimensions suits your frame of reference.

This doesn't help you.

The problem is that the observable universe, the Present, is a Minkowski x1,x2,x3,x4 manifold deformed by mass and energy according to Einstein's equations. However, the observable universe, the Present, is not the whole story. We also need to consider the universe at time t to include not just x1,x2,x3,x4 but also what I call the Absent - that part of the observable universe which is affected by quantum processes in dimensions very close to our universe but which form not the "real" universe but the Dirac sea of virtual particles and their antiparticle correlates.

The Absent is simply the Present from a different frame of reference. What we see as the Dirac sea in the vacuum is simply real matter in a universe whose shockwave of its own Present intersects with our own universe for a nothingth of a second. A different Present. Part of our Absent. But still part of Now.


The key word here is "vorticity". The world we see around us is a surface, a shockwave if you like, propagating through time. What we see as the present is merely the surface of the shockwave as it converts the highly entropic future into the zero entropy past. This surface appears to have the properties of a superconducting superfluid and yet we can't describe it as an ether or as anything real. We can only describe the particles that exist within it as wavelike entitities which when integrated over time look like vortex lines in a quantum superfluid such as helium 3. These wavelike entities, integrated over time, look like tubules of spacetime, fibres with a property of vorticity. They occur in different famililes, analogous to the families of vortices found in superfluid helium. Magnetic flux is an example of this superluid vorticity.


So, without getting too verbose, your problem really touches on the incompatibility of quantum mechanics and relativity. There is no aether. But what we see as the present is simply a surface between the past and the future. The rate at which a particular part of that surface migrates through time is a function of how much energy and or mass there is in its vicinity.

Hope that helped.

In the last paragraph you mention a surface of presence. Would this be comprised of mostly matter?
It stands to reason that the future is probably made of the same thing as the past. Mostly distance and energy. I see know reason why there must be a beginning or an end, Or why there should be only a single "Unified time entity" (Universe).

The understanding that have gained has led me to advance my "Jet Theory" a little further. I'll post it under the name "Infinity Theory" in the "not the standard model" Forum here on the site.

 

[brainstorm]

There is also mainstream evidence of a virtual sea of positrons/electrons popping in and out of existence. But to answer your question, we need to first assign a 'substance' to space and so this is as good as any.

If space was a "sea of particles," you are left with the problem of what exists in between the particles. For this reason, it makes more sense for space to be conceptualized as a continuous rather than discrete entity. The best candidate therefore, imo, is for space/time to be viewed in terms of overlapping field-forces, defined as distance/time among "tighter" fields as a result of those "tighter fields" being situated within "looser fields." More specifically, electromagnetic force is weaker than nuclear force and therefore creates "space/time" within atoms. Gravitational force is weaker than electromagnetic force, thus creating "space/time" within gravity fields for atom-constituted matter. Spacetime "fabric" at the largest astrophysical scale could be either the topography of coterminous gravity fields OR it could be some other force, even weaker than gravity that emerges to a significant degree only at perhaps the (super)galactic level. If nothing else, the "overlapping" of weak and tight force-fields would explain space/time without the problem of infinite regression into the question of what's in between the smallest particles.

 

[Fredrik]

What is space?

It's a big ball of wibbly wo...no wait, that's time.

Seriously though, there are only two kinds of answers to questions about reality: theories and garbage. Assuming that you don't want garbage, I can only tell you how space is defined in each theory. The definitions are mathematical, so you may not like this answer very much, but the only way to improve it is to include more details about the definitions, and I suspect that you wouldn't be interested in more details.

The very short version is that you define "spacetime" first, as a 4-dimensional vector space, affine space, or smooth manifold, and then you slice it up (either the whole thing or a part of it) into a one-parameter family of 3-dimensional subspaces or submanifolds that you call "space", while calling the parameter that labels the subspaces/submanifolds "time". In pre-relativistic physics, only one way to do the slicing is considered valid. In special and general relativity, there are infinitely many valid ways to do it.

Space: Distance as bands of history imprinted by photons and energy forces and occupied by mass.

What theory says that?

Are there space specialists?

People working with solutions of Einstein's equation (general relativity) can be considered spacetime specialists.

 

[brainstorm]

It's a big ball of wibbly wo...no wait, that's time.

Seriously though, there are only two kinds of answers to questions about reality: theories and garbage. Assuming that you don't want garbage, I can only tell you how space is defined in each theory. The definitions are mathematical, so you may not like this answer very much, but the only way to improve it is to include more details about the definitions, and I suspect that you wouldn't be interested in more details.

The very short version is that you define "spacetime" first, as a 4-dimensional vector space, affine space, or smooth manifold, and then you slice it up (either the whole thing or a part of it) into a one-parameter family of 3-dimensional subspaces or submanifolds that you call "space", while calling the parameter that labels the subspaces/submanifolds "time". In pre-relativistic physics, only one way to do the slicing is considered valid. In special and general relativity, there are infinitely many valid ways to do it.

I think the OP was asking about what constitutes spacetime at the physical/material level, not how it is defined mathematically, although that is also relevant.

 

[Naty1]

No one knows what space is,,,,, any more than they know what time is...or mass, energy, gravity...nor dark energy...for most we can describe the observational effects but not the fundamental origin nor "what is..."

It is believed they appear as superficially separate manifestations now but at the moment of the big bang were unified (combined into one high energy entity). The strong, weak and electromagnetic forces have been combined (unified) into one mathematical framework...and that has not, I don't believe led to new fundamental insights,...but gravity and the other entities have not bee "unified".

Space and time are in the eye of beholder...the faster an observer moves the smaller distant space becomes and the slower time appears to pass elsewhere. So while special relativity says they transform into one another as speed changes, GR says that both curve, that is, are warped, by gravitational potential...those relationships are the only ones that I can think of that might give a glimpse of what else may come.

QM suggests that at ultra small distance( space) and time scales, these entities morph into each other, become uncontrollably energetic and unrecognizable amdist quantum "foam", and none are thought to exist below Planck scales (of energy, space,time...

 

[franklinhu]

No one knows what space is,,,,, any more than they know what time is...or mass, energy, gravity...nor dark energy...for most we can describe the observational effects but not the fundamental origin nor "what is..."

You state quite accurately that no one knows what space,time,mass,energy, gravity or dark energy is.

Isn't this a rather pathentic state for physics to be in? With billions going towards fancy accelerator and neutrino experiments, you'd think we'd have the basics down. These are very fundamental concepts, yet we don't know what these are.

What is more troublesome is that any attempt at explaining these is considered "crackpottery" by definition and is immediately ignored or suppressed.

Now, I could easily give a mechanically plausible explanation for each of these concepts, but then, I would be considered a "crackpot", since doing so would mean tossing out the last 100 years of physics and most of physics' sacred cows. So how are we to find an answer to these questions when no one's willing to discuss the alternatives?

 

[turbo]

What is space? it's got to be the biggest thing in the universe. I'd even go so far as to say it defines our universe from (if there are any) other universes.
but what is it?
Is it literally a fabric of time? If so then how and/or what defines the past, present, and future physically?
Are there space specialists? What would you call someone who specializes in the study of the space time fabric?

May I suggest a book that might interest you? It is "The Philosophy of Vacuum" edited by Saunders and Brown. It's a pricey little book, so you might want to hunt for a used copy or borrow it from a library.

https://www.amazon.com/dp/0198244495/?tag=pfamazon01-20

 

[franklinhu]

If space was a "sea of particles," you are left with the problem of what exists in between the particles. For this reason, it makes more sense for space to be conceptualized as a continuous rather than discrete entity.

If we have a sea of particles, I would imagine that 'nothing' exists between those particles. I don't see how this is a problem. I suppose space could be considered on two levels. On one level, we have space composed of matter particles - "the poselectron sea". At another level we have space as simply being 'empty' (devoid of matter) space which still has measurable volume.

If you believe that space is some kind of continuous field, then you have the bigger problem of explaining how these fields are mediated through 'nothing' (the space devoid of matter). If you have no physical explanation, then you are building castles in the air. So, please explain how your 'fields' work from point A to point B with nothing between.

On the other hand, if you believe that space is made up of discrete particles, then we immediately have a medium through which all fields can be mediated. The descreteness also places limits on the smallest size and unit of time. Nothing can be infinitely divided into smaller pieces. I suspect the embarassment of infinities in the standard model is due to considerding space and time as infinitely dividible instead of being distinct quanta.

 

[Fredrik]

I think the OP was asking about what constitutes spacetime at the physical/material level, not how it is defined mathematically, although that is also relevant.

I know what sort of answer he expected. That's why I didn't feel like including all the details of the the definitions. What I said is still the best possible answer. I explained that there are exactly two kinds of answers to questions about reality: theories and garbage. I then described briefly what the relevant theories say. There can't be a more accurate way of answering the question, regardless of what the OPs expectations were.

People in general have really naive expectations when they ask questions about reality. They tend to expect theory-independent answers about the actual state of affairs (as if that makes sense), instead of answers in the form of "theory X says Y". They don't understand that we need a theory just to define the terms used in the question, or that once we have chosen a theory that defines the terms, the logical next step is to tell them what that theory says.

When someone asks a question that reveals such naive expectations, I think they should be given a proper answer. I think that even an answer that they don't fully understand, along with a hint that they need to change the way they think, is better than an answer that's dumbed down to the point where it looks like a straight answer about the actual state of the affairs "in terms they can understand".

The more specific question of "what constitutes spacetime at the physical/material level" can only be answered by taking the definitions I mentioned as starting points. In all of these theories, matter is defined in terms of curves in spacetime, or fields on spacetime. So at first glance, it seems that matter is fundamentally different from spacetime. However, in general relativity, the most accurate of these theories, a spacetime is defined by a smooth manifold and a metric, and the metric is a field. (In this context, a field is a local section of a vector bundle over the spacetime manifold). So one of the two ingredients in a spacetime is actually the same kind of "thing" as matter.

The spacetime manifold on the other hand can't be said to be "material" in any way I can think of. It is however "physical" in the sense that it's an essential part of a theory of physics. (What else can that word mean?)

 

[Fredrik]

You state quite accurately that no one knows what space,time,mass,energy, gravity or dark energy is.

Isn't this a rather pathentic state for physics to be in? With billions going towards fancy accelerator and neutrino experiments, you'd think we'd have the basics down. These are very fundamental concepts, yet we don't know what these are.

What is more troublesome is that any attempt at explaining these is considered "crackpottery" by definition and is immediately ignored or suppressed.

What you don't understand is that science can't tell you what anything "really is". Experiments can only tell you how accurate a theory's predictions are, and theories are just sets of statements that can be used to make predictions about results of experiments. Science is the process of developing new theories and finding out how accurate their predictions are. When we find a theory that makes accurate predictions, we feel that we can understand something about reality by making sure that we understand the theory. We will however never find out what something "really is".

The terms you list have exact definitions in theories that make absurdly accurate predictions about results of experiments. That's really the best we can hope for, so it doesn't mean that we don't "have the basics down".

It is sometimes the case that a new and better theory comes along and explains an axiom of the earlier theory. For example, General relativity explains Newton's law of gravity. But the new theory is based on another set of axioms, and the only thing that can explain those is another theory. So you can always argue that we don't understand "the basics", because what could possibly be more basic than the axioms of the most fundamental and most accurate theory we have?

This doesn't mean that we have failed to do science well, but it does mean that there are limits to what science can tell us. Unfortunately, science is the only way to make any kind of progress at all.

 

[franklinhu]

What you don't understand is that science can't tell you what anything "really is". QUOTE]

What do you mean? Science has told us exactly what 'Water' really is. It is 2 hydrogen atoms connected to an oxygen atom in an L shape. We have isolated out the component oxygen and hydrogen and proven they exist without a doubt. So, we do know what water really is.

The OP simply wants to know what 'space' really is and be given an answer like "it is made out of H2O" and not an excuse like "we can't ever tell what anything really is". If early chemists had that same attitude, do you think they would have gotten far?

I don't thnk it is beyond the ability of modern day science to find out what space is made out of. Maybe its made out of Higgs particles, or maybe out of my hypothetical poselectron particles. But to find it, scientist have to theorize what it is and then "look" for it instead of just waving their hands saying nobody knows, nobody cares, nobody can know. What is lacking is any attempt at making a testable theory of space.

Even with the Higgs boson, we are looking for something, we don't even know what it is except for it is massive. How can you find something if you don't know what you are looking for? At least the "poselectron" (if it exists) could be detected or refuted with currently available experimental apparatus. But of course, no one would believe such unmittigated crackpottery and so no one is ever going to look for it and we will never find the substance of space.

Is "nobody knows, nobody cares, nobody can know" really a legitimate postulate of science?

 

[MattRob]

I liked what Brainstorm said about Goethe's theory of colors. People have a knack for taking things and making them way too complicated. But then again, at the same time, Einstein and Newton only made advancements through thought experiments. The only reason we have relativity is because Einstein was so inquisitive and spent so much time thinking of abstract ideas.

The only way to get anywhere is with this sort of abstract questioning, but in order to make sure we're going in the right direction, we need to make sure our theories match current experimental evidence, which is where Goethe failed with this theory of colors. Speaking of which, our "theories" are actually just hypothesis until we actually experiment with them.

Anyways, Fredrik stole the words from my mouth. I was about to post about how science can only really confirm hypothesis through experimentation, which is, by definition, the scientific process. Forming our hypothesis is arguably bordering the realm of philisophy. We think of the universe, try to understand it in ways that make sense to us. We try to form a picture, and our picture says X should behave so. When X doesn't behave so, we're wrong, when it does, we test again and again until we're sure it doesn't. After all, it's only when we're wrong that progress can be made ;-) . How boring would it be if everything you thought of was right? (Though, it would arguably be quiet awesome. I guess it's more correct to say, how much fun would it be if other people were always right?)

Alright, almost forgot. Speaking of "making sure X behaves so", franklinhu, if the effects of relativity come from velocity increasing the number of reactions that must take place, then the Lorentz factor would be linear, since doubling speed doubles the units of distance you travel per unit of time. If we describe each particle pair as a unit of distance, than doubling the speed would double the number of required reactions. Tripling it would triple it, etc.
However, the Lorentz factor follows the equation of (since my keyboard doesn't have the actual "Lorentz" symbol :P )
L = c / sqrt ( c^2 - v^2 )
Which is certainly not linear. Time to go back to the drawing boards with that idea. No shame, when it comes to light bulb filaments, Edison was wrong several thousand times and he was only right once. Not to say his invention didn't make any difference :-)

EDIT: To expound on this a little more, it's not "nobody knows, nobody cares, nobody can know", it's more along the lines of a challange: "Come up with something that WORKS!", that is, when put to the text of experimentation.

Hmm... It seems just about everybody has their own little theory about the universe. There's nothing really wrong with that, it's just it can't be taken seriously unless it's proved itself through experimentation. Make the theory, write it out in MATH, so there's TANGIBLE implications. If reality follows the pattern, keep going, you may be onto something. If reality doesn't follow the math, don't worry, that just means your one of the six billion others who aren't revolutionizing science ;-)
If you want to do more in this area, then take courses in physics and get used to describing EVERYTHING with math. Once you've done that, then I'd say join the club. But I can't technically say that since I'm not "in the club"... yet :p .

Back to the original question, a little apology to the OP since we've gone so OT,
from my understanding space is the distance in-between objects. In the strict mathematical sense, it's a decay in the amount of force objects exert on each other. If gravity is a force, then this would hold true.
However, if gravity is a curve, which definitely seems to be the case, then space is really more of a 4 dimensional fabric, where the fourth dimension is time, as intrinsic to the fabric as the spatial dimensions are. Which, lol, didn't really answer the original question. So to answer that, then I think I'd say space is the gravitational potential an object has, along with it's relation of how strong other objects' forces exert on it. Essentially the same answer as the "strict mathematical sense", except with the gravitational potential bit added on.

 

[brainstorm]

If you believe that space is some kind of continuous field, then you have the bigger problem of explaining how these fields are mediated through 'nothing' (the space devoid of matter). If you have no physical explanation, then you are building castles in the air. So, please explain how your 'fields' work from point A to point B with nothing between.

If the universe consists of only force-fields with no external "container" for those fields, the fields could work in their own right, sui generis, without anything to mediate them except themselves. In other words, where there is no field-force of any kind there would also be no spacetime. Can gravitational fields end? Or do they just keep getting increasingly weaker ad infinitum? Do not all moving objects within them ultimately reach a point of curving back toward their source if they don't go into orbit within a different gravity-well? The problem with this is that I don't know what would cause light to turn around far from the center of a gravity-well except the possibility that spacetime curves in such a way that it has no other direction to go in. I suspect this is the case, because I have no reason to believe there is something empirical about spacetime except gravitation, which I believe must also be the medium for light since field-force has no mass and can be "tensed" and "relaxed" to make waves.

On the other hand, if you believe that space is made up of discrete particles, then we immediately have a medium through which all fields can be mediated.

How? That's like saying if alphabet soup is made up of discrete letters, then there is immediately broth for them to float in. You still haven't addressed the issue of the "broth" that has to be present for the particles to be discreet and thus have something in between them.

The descreteness also places limits on the smallest size and unit of time. Nothing can be infinitely divided into smaller pieces. I suspect the embarassment of infinities in the standard model is due to considerding space and time as infinitely dividible instead of being distinct quanta.

Fine, but a photon still has to get from one electron to another, so what does it go through to get to it? That's the issue here.

 

[MattRob]

Brainstorm, the force of gravity is an asymptote to the escape velocity.

Think of it this way, if every step you take gets you halfway to a doorway, then you'll never reach the doorway even with an infinite amount of steps.

In the same way, every moment gravity pulls back on an object is a "step" back, slowing the velocity of the object. However, gravity gets weaker as the object gets further away. So although it is an infinite number of additions, it is a finite number, the escape velocity, so light does not have to curve back to the source. But that still fits in with the idea that it can only exist in a gravitational field, since a gravitational field is endless, it can travel outwards for eternity and still be within some gravitational influence... I really hope I understood you correctly, lol.

Anyways, what was that about the Minkowski x1 x2 x3 x4 manifold earlier? Is it really true that according to mainstream science time is a dimension that is the same as any spatial dimension? I'm chasing an idea here I'm on the verge of starting a new thread on if that's the case, which would be the case if you can pick any three to be space and anyone to be time.

 

[Fredrik]

My claim that "science doesn't tell you what anything really is" may be too strong. I need to think about what I should say instead, but I don't have time right now. Probably not tomorrow either.

I stand by my comment that my answer to the OP is the best possible answer.

 

[brainstorm]

so light does not have to curve back to the source. But that still fits in with the idea that it can only exist in a gravitational field, since a gravitational field is endless, it can travel outwards for eternity and still be within some gravitational influence... I really hope I understood you correctly, lol.

I don't know if a gravitational field would be endless for light if the light was not able to crossover into a further gravitational field. I also don't know if spacetime-curvature due to gravity doesn't create paths between gravity-wells that have very little to do with the expected spatial relations between those wells. E.g. if a vehicle was going from Venus to Mars and Earth was not in the direct path between them, the vehicle would curve closer to Earth on its way to Mars, though this would be the straightest gravitational path it could follow.

Energy cannot be created or destroyed, so light moving away from a star must eventually find its way to some gravity-well, even if it only does so because of curving around according to whatever gravitation it generates on its own. Can you imagine EM radiation occurring in a context totally devoid of gravity?

 

[franklinhu]

Alright, almost forgot. Speaking of "making sure X behaves so", franklinhu, if the effects of relativity come from velocity increasing the number of reactions that must take place, then the Lorentz factor would be linear, since doubling speed doubles the units of distance you travel per unit of time. If we describe each particle pair as a unit of distance, than doubling the speed would double the number of required reactions. Tripling it would triple it, etc.
However, the Lorentz factor follows the equation of (since my keyboard doesn't have the actual "Lorentz" symbol :P )
L = c / sqrt ( c^2 - v^2 )
Which is certainly not linear. Time to go back to the drawing boards with that idea. No shame, when it comes to light bulb filaments, Edison was wrong several thousand times and he was only right once. Not to say his invention didn't make any difference :-)

The idea that speed increases physical travel length which then contributes to dilation effects isn't my idea. See "Simple inference of time dilation due to relative velocity"

http://en.wikipedia.org/wiki/Time_dilation

When considering anything that "measures" time, one must consider something ticking between point A and B to do the measuring. It is this distance, plus the velocity and a simple application of pythagorean theorem which cause the dialation. The situation you referred to would be a system where there is no distance between A and B, in which case, this system cannot be used to measure time in a practical matter and is really a special case of a^2 + b^2 = c^2 where a = 0 in which case b = c - a linear equation.

Come on people, this is first year physics - did you forget that already? Velocity increasing the reaction rate (which is equivalent to overall distance traveled through space and equivalent to the number of particles something would have to get past to get from point A to point B in my particle sea) is perfectly consistent with existing scientific thought.

What is strange is that this common derivation screams that there is some substance that light travels through which allows it to take this longer path, yet we don't believe an any such substance. Getting back the OP's question ... could that be 'space'?

What is stranger is that MattRob didn't realize he was disproving Einstein.

 

[harrylin]

[..] Back to the original question, a little apology to the OP since we've gone so OT,
from my understanding space is the distance in-between objects. In the strict mathematical sense, it's a decay in the amount of force objects exert on each other. If gravity is a force, then this would hold true.
However, if gravity is a curve, which definitely seems to be the case, then space is really more of a 4 dimensional fabric, where the fourth dimension is time, as intrinsic to the fabric as the spatial dimensions are. Which, lol, didn't really answer the original question. So to answer that, then I think I'd say space is the gravitational potential an object has, along with it's relation of how strong other objects' forces exert on it. Essentially the same answer as the "strict mathematical sense", except with the gravitational potential bit added on.

Well, geometrical space is certainly simply the measured distance between objects; and as such it's just nothing but math. But there is also the concept of something that is physically "there", in the void between material objects and that's what the OP apparently thought of with "it's got to be the biggest thing in the universe."
After reconsidering that question concerning General relativity (see also my earlier answer), Einstein concluded that space determines the metrical relations in the space-time continuum under influence of nearby matter - thus in his view, the gravitational potential and force relations are not space, but they describe the state of that space. That's the subtle difference between physics and math. ;-)

 

[Naty1]

You state quite accurately that no one knows what space,time,mass,energy, gravity or dark energy is.

Isn't this a rather pathentic state for physics to be in?

In a sense, yes!, yet medicine, for example, is in a similar state...just what is "life"? Why does one drug work and another not? What is sanity? It's along the lines Fredrick posted...hypothesis, testing, experiments... and usually elusive..

What is more troublesome is that any attempt at explaining these is considered "crackpottery" by definition and is immediately ignored or suppressed.

I agree...If you read books by Smolin, Thorne, Kaku, Susskind,Thorne, I don't think any would agree with Fredrick's (and others) earlier posts which he seems to be reconsidering. It's too common a theme in these forums,

An obstacle to genuine understanding of essentials, or fundamentals, in physics is that reality is not fixed...different observers sometimes see different things...both relativity and quantum mechanics have versions of this within their theoretical framework.

Don't let anybody convince you the sciences are not interesting is "what is" questions...it's just that such questions are very complicated and very subtle...and too many people hate to admit they don't have the answer.

 

[Grimstone]

What is space? it's got to be the biggest thing in the universe. I'd even go so far as to say it defines our universe from (if there are any) other universes.
but what is it?
Is it literally a fabric of time? If so then how and/or what defines the past, present, and future physically?
Are there space specialists? What would you call someone who specializes in the study of the space time fabric?

Space. the distance between one point and another.
also known as, the dream, game board we play our reality on.

 

[G01]

It's a big ball of wibbly wo...no wait, that's time.

wibbly wobbly, timey wimey...

 

[brainstorm]

Einstein concluded that space determines the metrical relations in the space-time continuum under influence of nearby matter - thus in his view, the gravitational potential and force relations are not space, but they describe the state of that space. That's the subtle difference between physics and math. ;-)

So your point is that if Einstein takes something for granted, that's enough to accept it as fact? If it wasn't, would you have any other basis for reasoning that such a thing as space/time exists beyond the interspursing of gravitational fields? If gravity takes place in space instead of itself constituting space, shouldn't there be some theoretical and/or empirical situation in which space is present and gravitation is not? What kind of situation would occur in space without the presence of gravitation?

 

[harrylin]

So your point is that if Einstein takes something for granted, that's enough to accept it as fact? If it wasn't, would you have any other basis for reasoning that such a thing as space/time exists beyond the interspursing of gravitational fields? If gravity takes place in space instead of itself constituting space, shouldn't there be some theoretical and/or empirical situation in which space is present and gravitation is not? What kind of situation would occur in space without the presence of gravitation?

No, why would you think that? Einstein had suggested the contrary for a while. That wasn't my point and thus I did not mention the arguments that made him finally change his mind. As I highlighted in bold, my point was the difference between the mathematical space concept and the concept of "the biggest thing" that the OP asked about. Anyway, the OP seems to have moved on.

 

[heatwaveqc]

http://en.wikipedia.org/wiki/Dark_fluid
best answer I've found so far. When looking at theories, I tend to judge based on two things: simplicity and explanatory power. I think that this theory has both, and gets rid of the two biggest issues I have with the current Standard Model of the universe: Dark Matter and Dark Energy.