M-Theory is a theory which 'combines' the five superstring theories

[drcrabs]

Waddup guys. To my understanding M-Theory is a theory which 'combines' the five superstring theories and supergravity.Also i understand that matematics is not yet advanced enough to make it work(or so I've been told) I am still not sure how this theory is meant to end up as a theory of everything. You thoughts?

 

[James Jackson]

When 'theory of everything' is banded about, it means a theory which unites all the four fundamental forces into one common framework. The forces are, of course, electromagnetic, strong, weak and gravitational.

 

[Mike2]

When 'theory of everything' is banded about, it means a theory which unites all the four fundamental forces into one common framework. The forces are, of course, electromagnetic, strong, weak and gravitational.

I believe a TOE would also explain where spacetime itself came from and how particles emerged from that.

 

[drcrabs]

Yea thanks i already know what a TOE is and the four fundamental forces are thanks ne way

 

[Mike2]

Waddup guys. To my understanding M-Theory is a theory which 'combines' the five superstring theories and supergravity.Also i understand that matematics is not yet advanced enough to make it work(or so I've been told) I am still not sure how this theory is meant to end up as a theory of everything. You thoughts?

Gravity is thought to be curvature of spacetime itself. But String Theory and M-theory are various dimensional submanifolds embedded in a background spacetime. Gravitons are thought to be some type of string or brane. So there seems to be a contradiction. Strings and branes are thought to be gravitons of gravity which is thought to be spacetime itself in other theories. So where did the background come from in the first place?

 

[Mike2]

Gravity is thought to be curvature of spacetime itself. But String Theory and M-theory are various dimensional submanifolds embedded in a background spacetime. Gravitons are thought to be some type of string or brane. So there seems to be a contradiction. Strings and branes are thought to be gravitons of gravity which is thought to be spacetime itself in other theories. So where did the background come from in the first place?

So what if they find a background independent formulation of string/M-theory? What would that mean? You would still have gravitons and all other particles explained in terms of this background, i.e. vibrations of something within a background space, right? The formulation would simply be background invariant, not depend on whatever spacetime is chosen in which to describe the theory, right? But that would still REQUIER a background, which the theory would not explain. Is that correct?

 

[selfAdjoint]

So what if they find a background independent formulation of string/M-theory? What would that mean? You would still have gravitons and all other particles explained in terms of this background, i.e. vibrations of something within a background space, right? The formulation would simply be background invariant, not depend on whatever spacetime is chosen in which to describe the theory, right? But that would still REQUIER a background, which the theory would not explain. Is that correct?

All the difference in the world between particles flying around in a curved, fixed, background space on the one hand, and particles causing the spacetime to bend, while it causes them to curve in their paths. Background independent means that the space is in the foreground, taking part in the physics, and dynamically altering and being altered.

 

[Mike2]

All the difference in the world between particles flying around in a curved, fixed, background space on the one hand, and particles causing the spacetime to bend, while it causes them to curve in their paths. Background independent means that the space is in the foreground, taking part in the physics, and dynamically altering and being altered.

How can gravity be both a curved spacetime and a particle moving through spacetime simultaneously? If gravitons are particles moving through a background spacetime, then where did the background come from? Even if it doesn't matter what the background is (it still results in the same physics), you still seem to need a background in order to calculate the particle properties. Where did that background come from? Is there a 5th force which does bend the background spacetime? If it doesn't matter what the background is in order to obtain the particle properties, then the particle properties cannot depend on the background, so the background, likewise, cannot be influenced by the particles, right?

 

[selfAdjoint]

How can gravity be both a curved spacetime and a particle moving through spacetime simultaneously? If gravitons are particles moving through a background spacetime, then where did the background come from? Even if it doesn't matter what the background is (it still results in the same physics), you still seem to need a background in order to calculate the particle properties. Where did that background come from? Is there a 5th force which does bend the background spacetime? If it doesn't matter what the background is in order to obtain the particle properties, then the particle properties cannot depend on the background, so the background, likewise, cannot be influenced by the particles, right?

All good questions. Nobody knows. If we quantize gravity by any method, there will be quanta of gravity. If our quantization is background independent - that is, it is a quantization of spacetime itself - then these quanta of gravity will also be quanta of spacetime. Einstein thought of "the field" as replacing spacetime, and there have been others who thought of spacetime as replacing the field! Quantize that!

 

[Mike2]

All good questions. Nobody knows. If we quantize gravity by any method, there will be quanta of gravity. If our quantization is background independent - that is, it is a quantization of spacetime itself - then these quanta of gravity will also be quanta of spacetime. Einstein thought of "the field" as replacing spacetime, and there have been others who thought of spacetime as replacing the field! Quantize that!

You understand the contradiction, don't you? You assume a continuous spacetime in order to calculate the quanta of spacetime. So which is it, right?

I'm trying to understand the meaning of background independence. Doesn't that mean an invariance of some sort, that the physics is the same no matter what the curvature of spacetime is. Is this right? I understand the term independence to be invariance, but you suggest it means quantization. Are you saying that invariance equal quantization. Maybe there is a principle to this effect that I forgot.

 

[nightcleaner]

If you start with nothing, and then make two somethings out of it, it should not surprise you if, when you add the two somethings together again, you get nothing. Does this mean that neither of the two somethings exists on its own? Of course not. This is the value of separation. A positron and an electron can be perfectly good somethings, until they happen together. Then they return to nothing again. The energy, or action potential, which results and propagates, wavelike, is not something, in itself, but only the reactions of the other somethings. Not?

Be well,

Richard

 

[Mike2]

If you start with nothing, and then make two somethings out of it, it should not surprise you if, when you add the two somethings together again, you get nothing. Does this mean that neither of the two somethings exists on its own? Of course not. This is the value of separation. A positron and an electron can be perfectly good somethings, until they happen together. Then they return to nothing again. The energy, or action potential, which results and propagates, wavelike, is not something, in itself, but only the reactions of the other somethings. Not?

Yes, I've often thought about this. I think it is expressed as a conservation of information law in the universe, though I don't have any proof of this. What I mean is that whatever structure exists is describable by some mathematical means. Its construction stands opposed to nothingness, obscurity, and chaos. There is information associated with its being, information necessary to describe it. However, there is also dissipative effects going on in the universe. For example, it might be that the expansion of the universe itself is a dissipative effect that increases the entropy in the universe. With expansion, more possible states exist for things to dissipate into. So there are dissipative effects that increase entropy which causes information loss, and there are constructive events which decrease entropy which increases information. It may be necessary for new, more complex structures to arise as the universe expands.

 

[Mike2]

You understand the contradiction, don't you? You assume a continuous spacetime in order to calculate the quanta of spacetime. So which is it, right?

String/M - theory does not explain where the background spacetime comes from to begin with, nor does it explain how the string/particles arise from the background. So of course their having problems with how spacetime is defined, which Calabi-Yau manifold is correct. And of course their having trouble deriving the mass of the particle. These problem seem inherent in how they approach the problem- that strings vibrate in the background, without defining the background or how mass emerges from it.

This inherent problematic approach may also affect Causal Dynamical Triangulation. For CDT also does not define where the background came from to begin with, nor does it say how mass arises from that background. So they too will probably not determine the correct ground state nor the masses of the particles.

 

[zelcon]

The M-theory does not state that it is the "T.O.E." or Unified Theory. Although it may be used to determine various possibilities and theories, but it is NOT a Unified Theory. There are countless properties of nature it cannot explain.
For more info on this subject, I recommend http://en.wikipedia.org/wiki/M-theory

 

[Mike2]

The M-theory does not state that it is the "T.O.E." or Unified Theory. Although it may be used to determine various possibilities and theories, but it is NOT a Unified Theory. There are countless properties of nature it cannot explain.
For more info on this subject, I recommend http://en.wikipedia.org/wiki/M-theory

The first sentence of your reference reads: M-theory is a solution proposed for the unknown theory of everything which...

Anyway, string theory isn't even able to calculate the thing it was originally investigated for, the masses of the particles. I wonder if this is not something problematic in the approach. Without first explaining how strings emerges from the underlying bulk, it may be that we are given a problem without initial conditions to calculate a unique solution. And this allows many different solutions from which we have no method of choosing the correct one. So we have the problem of the "Landscape".

And similarly, we cannot describe how strings or branes emerge from the background spacetime until we know what the background spacetime geometry is. So in order to get the masses, we need to know the background geometry which we cannot solve for until we have the initial conditions for that.

It seems at this point we may have no other option than to try to start from the very beginning of spacetime itself in order to make any progress at all.

Or is it the case that we are trying to find the initial conditions from the final solution, given the mass of particles can we find out how mass came into being in the first place. Is there an analogous situation from differential equations where we can derive the t=0 conditions from the t=something conditions? It seems problematic though to try to derive the given conditions from the given conditions. There is no way of knowing that your diff eq is correct to begin with, right?

 

[selfAdjoint]

The M-theory does not state that it is the "T.O.E." or Unified Theory. Although it may be used to determine various possibilities and theories, but it is NOT a Unified Theory. There are countless properties of nature it cannot explain.
For more info on this subject, I recommend http://en.wikipedia.org/wiki/M-theory

Whether or not M-theory will ever become a Theory of Everything, a theory that really did what the M-theorists would like to do - unify all four of the basic forces - would deserve the name. What are the "countless properties of nature it cannot explain"? emergent ones? They are still causally underpinned by particle physics. See self-organized criticality.

 

[Mike2]

Whether or not M-theory will ever become a Theory of Everything, a theory that really did what the M-theorists would like to do - unify all four of the basic forces - would deserve the name. What are the "countless properties of nature it cannot explain"? emergent ones? They are still causally underpinned by particle physics. See self-organized criticality.

Would String/M-theory explain where spacetime came from to begin with? Would it explain how particles emerged from the background to begin with?

 

[selfAdjoint]

Would String/M-theory explain where spacetime came from to begin with? Would it explain how particles emerged from the background to begin with?

Maybe it would. Consider the Ekpyric hypothesis as an example showing it could. And I believe present day physics has something to say about how the particles emerged.

 

[nightcleaner]

Hi Mike2

You ask "Would String/M-theory explain where spacetime came from to begin with?" This is not an uncommon question. It gets asked a lot in one form or another. To begin, let me make the assumption that String/M-theory certainly would answer the question if it could. Could String/M-Theory answer the question? I believe I know the answer to that, even though I am not able to function as a String/M-theorist. No.

Let me rephrase the question just a little, to generalize it to a more fundamental question. Where did spacetime come from to begin with? You see I have removed the part about String/M-Theory. I don't mean to avoid the intent of your quetion, as I hope to show in a moment.

Where did spacetime come from to begin with? I am sure you don't mean, "Who thought of the idea of spacetime?" I think you are asking about the physical origins of the physical observables.

Then consider the set that contains all of space and all of time and all of the relationships between space and time. This set contains the first time and all of the space present at the first time, as well as the last time and all of the space present at the last time, and all of the times and all of the spaces between the first time and the last time. Is there any space or any time or any spacetime that is not contained in the set of all spacetime? I think you will agree that there is not and in fact cannot be. Now let us return to the form of your question. You ask where spacetime came from to begin with. Where? Surely the place must be contained in the set of all spacetimes. And when, as you say, to begin with? Surely that time must also be contained in the set of all spacetime.

So the question, it seems to me, has no meaning as it is stated. You are asking, what part of spacetime is not part of spacetime!

Surely String/M-theory cannot answer a question that has no meaning. So the answer to your original question as originally stated can only be, No.

I don't want to seem harsh. You have shown great merit in attempting to think about these difficult things. But if you really want an answer, you have to go deeper. You have to think about what spacetime is. You have to transform your question, and your vision. You have to learn to think as a creature who inhabits more than our common three dimensions of space and one of time.

And there is so much more.

I wish you well. Have fun thinking.

Richard

 

[nightcleaner]

Maybe it would. Consider the Ekpyric hypothesis as an example showing it could. And I believe present day physics has something to say about how the particles emerged.

Hi selfAdjoint

I don't find anything on Google about Ekpyric hypothesis. It asks if I mean Ekpyrotic hypothesis, which seems to have something to do with theology. I don't have much interest in studying things that cannot be known so I did not go there.

Ekpyric. Out of the fire, as my memory of Greek serves me? Or maybe, just out of fire. That sounds right, since I find in the literature (Weinberg, The First Three Minutes, for example) that particles are thought to have condensed out of the cooling, expanding energy ('fire') sometime after the big bang.

Could you be more specific? I miss chatting with you here.

Richard

 

[Sempiternity]

nightcleaner, are you just saying that the question is meaningless simply because outside of the "set of all spacetime," space and time isn't defined? Which would be like asking what happened before the beginning? It's a meaningless question because if time was created at the beginning, there conceivably can't be a "before the beginning" if there's no conception or notion of time 'before' it was created.

(Spacetime, in The Elegant Universe, is defined as "A unsion of space and time originally emerging from special relativity. Can be viewed as the 'fabric' out of which the universe is fashioned; it constitutes the dynamical arena within which the events of the universe take place.")

Aside from this matter, M-Theory does explain where spacetime "came from," or it's origins. M-Theory makes usage of cosmic membranes that forms a multiverse, or a collection of many universes.

Michio Kaku explains in Parallel Worlds that the universal law that everything abides by is the quantum principle. He says that even when there is nothing at all, the quantum principle remains, and according to the quantum principle, even nothing is unstable. Before there was anything, there was nothing. This 'nothingness' bubbled with uncertainty due to the quantum laws and these bubbles spontaneously and arbitrarily expanded into a great multitude of baby universes. Michio Kaku conjectures that from this sea of bubble universes, our universe was formed, but of which is only one out of the myriad of universes formed in the beginning from the quantum laws.

 

[nightcleaner]

Hi Sempiternity

Well, yes, that is what I am saying, but beyond that, I believe what is required for better understanding of the origins of measurable phenomena, is a view which transcends our customary view of three dimensions of space and one of time. "Spacetime" is a concept which was advanced by Einstein and Minkowski to indicate the equality of space and time, in which questions about what came before the beginning or what lies outside the boundaries of our universe become meaningless. Better questions are required to explore the idea of what, if anything, lies outside the definition of spacetime.

I would like to try to encourage people who ask this kind of question to evolve beyond the 3 space 1 time mindset. I am sure you will agree that the branes and the bulk in which they are said to reside are not adequately described by three dimensions of space and one of time. Quantum theory requires us to study imaginary numbers, the complex plane, non-commutative algebras, higher dimensional geometries, and other mathematics which go beyond our ordinary visualizations of reality.

thanks,

Richard

 

[Sempiternity]

Thinking "outside of the box" is certainly something that must be done when dealing with such unusual ideas and concepts. It's a mind-bending journey attempting to grasp the conceptuality of multiple dimensions and fundamental origins, which makes your encouragement very well-founded :)

 

[Mike2]

Of course I meant "How did spacetime come into existence to begin with" and not where or when. The only answer is that it grew from a singularity. How it grew, by classical or quantum means I don't know.

Branes colliding to form our present spacetime only beg the question as to where the branes come from and how the spacetime in which the branes move came into existence.

I can't accept that spacetime arose from nothing through quantum effects. For quantum effects only effect things that exist, or at least can be calculated as if they exist. It seems quantum mechanics can only be done by using a background of space and time. Thus it assumes the existence of spacetime and so cannot be used to explain how spacetime emerged to begin with.

 

[Sempiternity]

On page 94 of Parallel Worlds, Michio Kaku further explains the concept of something from nothing:

The matter content of the universe, including all the stars, planets, and galaxies, is huge and positive. However, the energy stored within gravity may be negative. If you add the positive energy due to matter to the negative energy due to gravity, the sum may be close to zero! In some sense, such universes are free. They can spring out of the vacuum almost effortlessly...

This idea of creating a universe from nothing was first introduced by physicist Edward Tryon of Hunter College of the City University of New York, in a paper published in Nature magazine in 1973. He speculated that the universe is something "which happens from time to time" due to a quantum fluctuation in the vacuum.

 

[Spin_Network]

Of course I meant "How did spacetime come into existence to begin with" and not where or when. The only answer is that it grew from a singularity. How it grew, by classical or quantum means I don't know.

Branes colliding to form our present spacetime only beg the question as to where the branes come from and how the spacetime in which the branes move came into existence.

I can't accept that spacetime arose from nothing through quantum effects. For quantum effects only effect things that exist, or at least can be calculated as if they exist. It seems quantum mechanics can only be done by using a background of space and time. Thus it assumes the existence of spacetime and so cannot be used to explain how spacetime emerged to begin with.

Do you accept that at a singularity, everything exists?...I mean that everything you can think of is located at one point..the Singularity.

But then one has to consider the Vacuum?..Is this also within the Singularity? is there a Space Vacuum Of minimum content external to the Singularity?

The Singularity contains the Maximum Energy at the Minimum Location, is this similar(one the same), to the Minimum Energy contained at the Maximum Location that is Space Vacuum?..can the Bounce be reached from a Space Vacuum containing Singularity Location, and also from a Singularity, containing a Vacuum Point?

 

[Mike2]

Do you accept that at a singularity, everything exists?...I mean that everything you can think of is located at one point..the Singularity.

But then one has to consider the Vacuum?..Is this also within the Singularity? is there a Space Vacuum Of minimum content external to the Singularity?

The Singularity contains the Maximum Energy at the Minimum Location, is this similar(one the same), to the Minimum Energy contained at the Maximum Location that is Space Vacuum?..can the Bounce be reached from a Space Vacuum containing Singularity Location, and also from a Singularity, containing a Vacuum Point?

As I said in another post recently, a single point, which is what a "singularity" is cannot be described; it does not exist. there are no features that a single point has all by itself. Certain fields can have different values at different points. But if all that exists is a single point, singularity, then there is nothing else with which to compare it to, so it has no description. So it cannot exist... does not exist in the sense of describing it with respect to other points that do not yet exist.

Now that I think about it, does this argue for a continuous growth of spacetime from a singularity, or a quantum leap? At what point in its growth from nothing does it then exist?

 

[Sempiternity]

at a singularity, everything exists

Perhaps not everything, but at least everything known in our universe. If parallel universes do exist, then a singularity origin wouldn't have contained everything that exists, just everything in the known universe.

 

[Spin_Network]

Now that I think about it, does this argue for a continuous growth of spacetime from a singularity, or a quantum leap? At what point in its growth from nothing does it then exist?

Mike2, in my post I have try to convey a scenario whereby there are different singularities ,where one contains the other?..then if one emerges from a specific location, say at a point ofMaximum Energy at the Minimum Location ..then this location is/can..be contained within another Singularity!..the Background of which can evolve into a separate Singularity.

Let me specifically state again:One singularity that has a Maximum Energy at the Minimum Location is quite distinct and separate from another singularity that is Minimum Energy contained at the Maximum Location these two concepts are quite individual, whilst they can evolve from one to the other, the specific choice of one does mean important Leaps and Bounds for understanding.

Another poster 'Sempiternity' has convieniently highlighted this problem.

Einstein has I believe tackled these very notions above, but in a different context, let me relay this Einstein Quote How are we to proceed from this point in order to obtain a complete theory of Atomically constructed matter? In such a theory, singularities must certainly be excluded, since without such exclusion the differential equations do not completely determine the total field.

Now later Einstein gives a complete example of Quantum Wave "jumping", with respect of motion form one frame of reference to another. I believe it was with Dr Rosen?

 

[Mike2]

Let me specifically state again:One singularity that has a Maximum Energy at the Minimum Location is quite distinct and separate from another singularity that is Minimum Energy contained at the Maximum Location these two concepts are quite individual, whilst they can evolve from one to the other, the specific choice of one does mean important Leaps and Bounds for understanding.

Then what do you mean by singularity. My understanding is that a singularity is where you have infinite value only at one particular point. So if the whole universe consisted of only one particular point, then there is no comparing the value of a field with another point which does not exist yet.

I wonder how you would mark the differences between manifolds of slightly different differential sizes. It seems to me that if you don't have things like particles or strings yet, then there would be some sort of invariance with size, no means of distinguishing the quality or value of empty but growing universes. What's this called, conformal invariance? You'd have to know which point was the starting point and which points in the differential region were not the singualar point. But I think that the idea of a manifold growing from a singularity is that after it grows, you can no longer tell which point is the center. It seems then that you have some other invariant properties such that each point is just as likely to be the center as any other point. The laws of physics are the same at every point in space; there is then no preferential frame of reference for any measurable thing. And if that is so, then how do you even measure the size of the universe as it grows? Maybe that is why it may seem that space is broken into portions of the plank volumes. Below such scales there is no distinctions that can be made, no "measureable" observables.

 

[nightcleaner]

Perhaps it would be helpfull to refine some definitions. For example, the idea of a point. There seems to me to be nothing measurable about a point except its position in some extended matrix of points. We need to have a mathematical treatment to approach the idea of a point. Does mathematics describe reality? Yes, but not to the perfection of a point. No matter how subtly we build our mathematical systems, there is always a region of discontinuity between the mathematical description and the actual behavior of the observable. This seems to me to approach the status of a universal law.

For example, we may take a simple surface, perhaps one side of an envelope containing some object so that the paper is not flat. Now we may try to measure the surface area of some curved region of the surface. Perhaps we draw tiny triangles, made of short, straight lines of uniform length and known area, all over the surface. Then we may get an idea of the surface area by counting up the triangles and multiplying by the surface area of one triangle.

However small we make the triangles, there will alway be a region of discontinuity where the point of intersection of the triangle is not actually on the surface of the paper. So, the surface area we calculate using the tiny triangle method is not precisely the surface area we are trying to measure, but merely can be made close enough for our purposes by making the triangles smaller.

This can be reduced to the absurdity of trying to measure the surface area of the paper by counting up the number of mathematical points it contains. Clearly we get an infinity if we try to do so. By means of calculation and measurement, we can only hope to get a useful approximation of surface area. The same is true for all other calculations and measurements we undertake.

Mathematics is beautiful and perfect, but it is not reality.

A point is a mathematical concept, not a measurable reality.

As I recall, the idea of the big bang came from the observation that the universe we can see is expanding. It seems logical that if you could follow the paths of all the particles in the universe back in time, you would find that they had a common origin, a single point, at which space and time all the universe we know occupied a singularity. It isn't practical to actually follow all the particles back in time, but we can do calculations to show what might result.

There was some argument at first about whether the particles would actually come to a singularity. Maybe they just came into some close region of points, not actually a single point. But IIRC this argument was resolved in favor of the singularity. Gravitational forces would become immense, and no surface irregularities could endure. The universe, run backwards, would have to collapse into a perfect sphere, which would then have to collapse into a single point.

Now a single point has no possibility for differentiation. It can by definition only have a single quantum. This is what led Stephen Hawking to conclude that no information could possibly pass through. Of course, we all know that Dr. Hawking has reversed his opinion on this point. Perhaps he has come to believe that the universe is too imperfect to ever be resolved into a single perfect mathematical point. Saved by imperfection! This sounds like chaos theory.

I have to surrender this telephone line. But this conversation is interesting and I hope to resume it later.

Thanks,

Richard

 

[Mike2]

As I recall, the idea of the big bang came from the observation that the universe we can see is expanding. It seems logical that if you could follow the paths of all the particles in the universe back in time, you would find that they had a common origin, a single point, at which space and time all the universe we know occupied a singularity. It isn't practical to actually follow all the particles back in time, but we can do calculations to show what might result.

There was some argument at first about whether the particles would actually come to a singularity. Maybe they just came into some close region of points, not actually a single point. But IIRC this argument was resolved in favor of the singularity. Gravitational forces would become immense, and no surface irregularities could endure. The universe, run backwards, would have to collapse into a perfect sphere, which would then have to collapse into a single point.

Now a single point has no possibility for differentiation. It can by definition only have a single quantum. This is what led Stephen Hawking to conclude that no information could possibly pass through. Of course, we all know that Dr. Hawking has reversed his opinion on this point. Perhaps he has come to believe that the universe is too imperfect to ever be resolved into a single perfect mathematical point. Saved by imperfection! This sounds like chaos theory.

If the universe was ever smaller than the smallest particles, then it is clear that particles emerged out of the spacetime that existed before that.

My point is that before particles emerged, there was no way to gauge the size of the universe or how long it existed. Nothing existed with which to compare how long it was at that size or what size it was at that time. Somebody might suggest that you can gauge the curvature of space with its size, but that would be with respect to an arbitrary coordinate system. It becomes scale-invariant, gauge-invariant, where metrics of time and space have no meaning. This is probably the state of maximum symmetry.

Then for some reason this symmetry was broken. This probably gave rise to particles, perhaps not yet massive. And from then on time and space became measurable. But before particles, there existed no preferred metric with which to even measure time and space. So it was not even possible to talk about energy contained in the universe before then. The total energy of the universe, then is probably related to the process of this maximum symmetry breaking process. Perhaps this is calculable in principle, irrespective of what we observe. So again it looks as though we cannot know the true nature of spacetime until we know how particles emerged from it.

 

[Canute]

Hi folks

This discussion is amazing. IMHO it's more philosophically interesting and dispassionately intelligent than any of the discussions of reality that I've seen in the Philosophy threads, and I've always assumed it would be the other way around. I shall come here more often.

Nightcleaner - I'd like to comment on your last post just to see if I'm understanding you right, and perhaps to widen the discussion a little.

Perhaps it would be helpfull to refine some definitions. For example, the idea of a point. There seems to me to be nothing measurable about a point except its position in some extended matrix of points. We need to have a mathematical treatment to approach the idea of a point. Does mathematics describe reality? Yes, but not to the perfection of a point. No matter how subtly we build our mathematical systems, there is always a region of discontinuity between the mathematical description and the actual behavior of the observable. This seems to me to approach the status of a universal law.

I also feel that the discontinuity between reality and the mathematical description of reality is shown by this argument. Any argument for reifying fluxions or infinitessimals ends up as a reductio ad absurdam demonstration that the idea contradicts reason. Physicist Peter Lynds has reached this conclusion, and has recently published a couple of papers arguing that the idea of points in time or 'instants' is incoherent.

The discontinuity between the mathematical concept of reality and what is actually the case is also evident from the paradoxicality of motion when it is modeled mathematically but not when apparently real things are apparently moving. It can also be seen by the difference of opinion over whether the number line is a continuum or a series of points, and the same difference of opinion arises over whether spacetime is a continuum or a series of points.

When we think about the physics of the universe perhaps we carry over a mathematical concept that is not applicable to the actual fabric of reality, the notion that it must be one thing or the other. For example, we assume that spacetime is either a continuum or a series of points and that tertium non datur applies, But contradictions arise which suggest that it is neither, or both. In similar fashion we have the wave-particle duality in QM and the 'hypothesis of duality' in M-theory. The same paradox arises in discussion of whether a true theory of the universe should be background dependent or not. According to reason it cannot be either exclusively, as Mike2 points out. It seems rather like a metaphysical question, and I would argue that it is one. (Which is why I was suprised to come across this discussion here).

It is worth saying then, in the light of all these paradoxes, contradictions and antimonies, that in the 'nondual' or 'Middle Way' cosmological model (Buddhism, Taoism, Sufism, Christian mysticism, Advaita Vedanta etc - aka the 'mystical' view) spacetime is not fundamental, and what is fundamental cannot be properly characterised as being either a continuum or a series of points, as either a background or not-a-background, as spatially extended nor not-extended, as temporal or a-temporal, and so on. It is 'something' that is 'nondual' and which transcends all these distinctions. It is the Tao, Unicity, Allah and so on.

Don't panic, I'm not going to make an argument for this view here, it would get the thread closed down. But you have to admit that this is some coincidence. Perhaps it suggests that phsyicists and mystics need to talk to each other more, now that physicists have finally proved for themselves that naive realism is nonsense.

It is as yet still possible that it is a mistake to apply the tertium non datur rule to reality itself, and if so then in this sense one has to transcend reason in some way to resolve these antimonies and make sense of reality. (One benefit of assuming this to be the case is that it would immediately explain the existence of metaphysics, for if it were true then metaphysical questions would inevitably be undecidable, since both their answers would be false).

Suspending the usual laws of logic is, after all, what we do in quantum theory, and if spacetime is in some strange way both extended and unextended then nonlocality is immediately explicable rather than incomprehensible. The universe would simply exist in a superposition of states.

Mathematics is beautiful and perfect, but it is not reality.

Mostly I agree, but have you come across the mathematics of George Spencer Brown? He presents his 'calculus of indications' (Laws of Form, 1967) as a model of how forms arise from the void, or in other words a model of cosmogenesis. His calculus is 'nondual' in structure, thus quite unlike most mathematical schemes, and is thus able to model the 'mystical', 'Middle Way' or 'nondual' model of reality.

I would say his mathematics is as close to a conceptual model of the cosmos as can be, and it may be the one exception to your statement. (He asserts he is a 'Buddha' by the way, and was a good friend of Wu Wu Wei, the Irish Taoist philosopher and mystic, now dead. He was one of the Russell, Whitehead crowd, and Russell praised his book 'Laws of Form'. However it sank without much of a trace. Too mathematical for mystics and too mystical for mathematicians. He still has a small but loyal fan club. I recommend him whenever I can).

As I recall, the idea of the big bang came from the observation that the universe we can see is expanding. It seems logical that if you could follow the paths of all the particles in the universe back in time, you would find that they had a common origin, a single point, at which space and time all the universe we know occupied a singularity. It isn't practical to actually follow all the particles back in time, but we can do calculations to show what might result.

Yes. But there is something odd about all this. It is not right think of the BB as happening at a point within spacetime, so I'm told, since it happened at every point in spacetime at once. In this case, how can we retrace a particle back to the beginning, for all of them were everywhere at once in the beginning, and all points were the same point, which itself was not at any particular place or time. The scientific idea of the BB causes me what I think they call cognitive dissonance.

It seems more plausible to me to imagine that time is a mere appearance, and that at a deep level of the analysis of reality the BB is happening right now, and always will be. More scientifically, this could be stated in terms of frames of reference and the many different 'slices of spacetime' that different conscious observers can consider as their particular 'now'. Perhaps there is a fundamental frame of reference, an ultimate observer-actualised 'now', in which nothing ever really happens, as Buddist masters and their like argue.

Now a single point has no possibility for differentiation. It can by definition only have a single quantum. This is what led Stephen Hawking to conclude that no information could possibly pass through.

Yes. Leibnitz concluded that something undifferentiated could not exist in spacetime, and it seems to me he was correct. Likewise something beyond spacetime cannot be extended in time or space, so cannot exist in the usual sense. But it could be something like a curled-up dimension in string theory, and in this sense it could exist. One would have to say that it exists, but that in a sense it does not exist, since it does not exist in our normal sense of the word 'exist' but exists unextended in any of the four dimensions of spacetime. Perhaps one could say it is. In this view spacetime would be a mere appearance or epiphenomenon emerging from a deeper underling reality or dimension. Spencer Brown suggests that this happens by a process involving the making of distinctions or 'indications' in an underlying dimension or void, consistent with Lao-Tsu, Nargaruna and the rest.

Of course, we all know that Dr. Hawking has reversed his opinion on this point. Perhaps he has come to believe that the universe is too imperfect to ever be resolved into a single perfect mathematical point. Saved by imperfection! This sounds like chaos theory.

He doesn't really say this does he? It suggests desperation to me. I'm not sure I understand why Hawking is considered such an important thinker, but then I can't follow his mathematics so can't really comment. For sure he must be a better mathematician than he is a metaphysician.

I have to surrender this telephone line. But this conversation is interesting and I hope to resume it later.

I very much hope you can.

Cheers
Canute

 

[nightcleaner]

Hi Canute

Thanks for the thoughtful post.

Philosophy, like mathematics, seems to me to be free to think of space and time as infinitely divisible. Physics seems to find otherwise. Why is this?

Physics is tied to observables. We can and do speculate about all sorts of unmeasurables, but that isn't encouraged or respected, even when it is lots of fun. Instead, the ultimate test in physics is one of nuts and bolts. That may be why physics lags behind mathematics, and has often found mathematical formalisms already in place that describe newly discovered physical relationships.

So mathematics has proven itself a good guide to exploring unknown physics. Philosophy and mysticism, less so. But that does not rule out the possibility, so it seems to me, that philosophy and mysticism will ultimately play a role in our physical understanding of the universe.

Mysticism is not a pretty word in physical circles. Mystical statements, so it seems to me, reduce to the simple affirmation, "I saw it." That is fine and it is very satisfying to be able to see things for yourself, but it isn't physics. What we need in physics is tangible objects that behave consistently when placed in controlled situations. Mysticism and philosophy rarely provide anything like that.

That is not to say that mysticism and philosopy have nothing to offer. It is only that we cannot appeal to them as authorities. I personally have found much of value in the Tao Te Ching, and in other "religious" studies. And it is not uncommon, especially in the popular science genre, to give a knowing nod and wink to the role inspiration plays in the scientific process.

I am glad that Peter Lynd has found in favor of temporal quanta, but it is not a new idea. Discrete quanta of space have been a nuts and bolts fact since black body radiation and the ultraviolet catastrophe were investigated physically more than one hundred years ago. Spatial infinitessimals lead directly to infinite energies, which are not observed.

Instead, we observe that spatial and temporal measurements have a microscopic limit. This limit is calcuable and gives us the Planck length at about 10^-33 cm, or, if you are new to the formalism of very large numbers, one centimeter (half an inch) divided into 1,000,000,000,000,000,000,000,000,000,000,000 pieces. That is pretty small.

In fact the Heisenburg Uncertainty Principle begins to take effect at much larger scales, and the effective limit to our ability to directly measure things leaves us gasping at anything smaller than a proton, about 10^-9 cm, altho as I recall the Fermi limit on observation of particles goes further down to about 10^-12 cm.

Here on the Strings, Branes, and Loop Quantum Gravity board, we are trying to follow the progress of the really deep divers, who are currently discussing the structure of spacetime. The string theorists have for the past thirty years or so given us a start on a potentially physical approach to this topic, but there is dissatisfaction in the ranks, where testable results are demanded. It appears that string theory has given us no testable results, nor even any falsifiable predictions. Hence a certain consternation in physical circles.

Branes are a part of M-theory, an outgrowth of string theory. In my view, string theory takes the one dimensional case, and brane theory expands that to higher dimensionalities. Loop Quantum Gravity and Causal Dynamic Triangulation have had some success with other approaches, and Lee Smolin (LQG) has made what may be falsifiable predictions, so that is some progress. Essentially all these approaches are trying to fit geometry to what is known of spacetime, and the goal is to find the formalism which will pull the great white rabbit of the universe as we know it out of the black hole hat.

I am still studying the mathematics, and my poor attempts at visualization have been dismissed by some of the heavyweights around these boards. I persist, hoping to see for myself why my thoughts about densely packed expanding Planck Spheres are useless. I am not there yet. Actually, CDT seems to me to be an expensive and difficult way to generate Planck spheres, but I am glad someone working at the Planck scale has managed to attract some attention.

The stakes in this contest are rather high. One imagines teleportation, faster than light travel, plentiful energies accessible anywhere. New worlds upon which humans can conduct their petty squabbles and live out their archtypal histrionic dramas. Who finds the answers to these questions will be as the first bacteria in a freshly opened can of stew.

My goal is more modest. I merely wish to catch a glimpse of reality as it may be without the clouds of obstrefucation. I want to remove the scales from off mine eyes, lift the mystic veil from the face I had before the mother was born, take a clean inspiration, get a glance, with Paul Erdos, of the pages of The Book.

I did spend a few weeks with the George Spencer Brown book. It seems to address the root of all our mathematics and philosophy, and perhaps of mysticism as well. If I recall correctly it starts with an empty void and presumes one must make a mark upon it, and then goes on from there to generate addition and ratiocination and so on. I think I followed the first few chapters, but did not go through all of the derivations of mathematics, except to verify that it all looked reasonable. I should like to look at it again some day.

Anyway I am always glad of intelligent conversation to ease our passage.

Thanks for being here, and for my part, welcome.

Richard

 

[nightcleaner]

If the universe was ever smaller than the smallest particles, then it is clear that particles emerged out of the spacetime that existed before that.

My point is that before particles emerged, there was no way to gauge the size of the universe or how long it existed. Nothing existed with which to compare how long it was at that size or what size it was at that time. Somebody might suggest that you can gauge the curvature of space with its size, but that would be with respect to an arbitrary coordinate system. It becomes scale-invariant, gauge-invariant, where metrics of time and space have no meaning. This is probably the state of maximum symmetry.

Then for some reason this symmetry was broken. This probably gave rise to particles, perhaps not yet massive. And from then on time and space became measurable. But before particles, there existed no preferred metric with which to even measure time and space. So it was not even possible to talk about energy contained in the universe before then. The total energy of the universe, then is probably related to the process of this maximum symmetry breaking process. Perhaps this is calculable in principle, irrespective of what we observe. So again it looks as though we cannot know the true nature of spacetime until we know how particles emerged from it.

Hi Mike2

As selfAdjoint said, modern physics does have much to say about how particles came out of the original fire. Symmetry breaking does have something to do with it, but as I recall it usually speaks in terms of forces rather than particles. I think the evidence is strong that particles as we know them in the standard model are not fundamental. There must be, it seems to me, some underlying geometry of spacetime which leads to our observations.

Perhaps CDT or LQG or another such will lead us up to the Fermi limit. I am glad to have this forum to discuss the progress, and to test my understanding against that of other posters. Marcus has the right idea, I think, in working to increase our exposure to ideas like CDT. I try to read the maths, but still struggle with basic terms. Lately I have been trying to catch on to the idea of indices and brackets.

We need the most articulate and definite language possible, and that seems to be the intersection of mathematics and physics. Perhaps you would like to begin a discussion here of what is known, as revealed by popular authors such as Guth, Greene, Weinberg and others. I would be willing to go back to those sources. Review is good. Or we can use our timespace to explore what is going on right now as recorded in arXivs. I have been thinking of trying to recover the condensed matter work as it may apply to our geometries, but havn't done anything serious in that direction yet. Maybe you would like to find out what is known about the emergence of particles.

I will go look through my copies of Weinberg et al, and try to give you some thoughts on where to start with emergent particles. I guess if I were doing an internet search, I would start looking at virtual particles.

I hope to return to this next week, sooner if possible. Of course, there is much todo going on in the next few days. The gods are bowling and we will probably be interested in what the thunder says. Exciting times.

Be well and thanks,

Richard