3, 4, and Extra Dimensions - General Discussion

[don]

Just some general questions about our existing 3 or 4 dimensions and extra dimensions ...

1. What is the basis for calling something a "dimension"?

2. Why is our physical universe considered to be 3 dimensions instead of ONE dimension, called "physical space", that simply has 3 "lines of movement" within it (up-down, left-right, forward-back) ... or FOUR dimensions (1-D point, 2-D line, 3-D plane, and 4-D cube)?

3. If our 3 dimensions are based on measurements in different directions, then what about the "air" inside of a cube? We can measure that, so why isn't it called a dimension also?

4. Why is time considered to be a dimension, since it has no physical properties (particles, mass, energy, etc.), cannot be observed, etc.?

5. If time is considered to be a dimension simply because its effect can be measured, then why are conscious and unconscious not considered to be dimensions? The effects of both can be "measured", or indirectly observed, just like time, and are not limited to the brain function of human beings (intelligent life).

6. Would it be possible that the expansion/acceleration of the universe is actually "causing" time to exist? When this expansion/acceleration stops, will time stop, creating eternity?

7. I keep reading that our universe is considered to be flat, but that word does not fit, since flat describes only a 2 dimensional plane. Our universe obviously has some thickness to it, so it should be called a cube in the shape of a square or rectangle, no? How thick is the universe? Is it a rectangular cube or a square cube (The Borg will love this one <snicker>)?

8. Is there any "substance" (natural or man-made, sub-atomic, atomic, molecular, etc.) on Earth that resembles the construction of the universe -- great expanses of "something" (the vaccum) with sparse clusterings of mass and energy (galaxies) here and there?

9. Why are the 4 "forces" not considered to be "dimensions"?

10. What do we expect to find in the warped or normal extra dimensions?

[jamarsa]

2) Why is our physical universe considered to be 3 dimensions instead of ONE dimension, called "physical space", that simply has 3 "lines of movement" within it (up-down, left-right, forward-back) ... or FOUR dimensions (1-D point, 2-D line, 3-D plane, and 4-D cube)?

Ha!! The same wild thoughts as me... We are thinking in the same direction!! Telepathy, perhaps? Would it be the effect of another dimension?

Why are the three 'spatial' dimensions interchangeable? The obvious answer would be that they are the same dimension. I am thinking now that dimensions are expressions of several 'major' universe properties.

Why, if the time is another dimension, we cannot go backwards as we go forward, or accelerate/deccelerate the passing of time (without extreme conditions., as blackholes)? Maybe because it is the expression of another 'property', much less ductile than the 'spatial' one.

[don]

We are thinking in the same direction!! Telepathy, perhaps? Would it be the effect of another dimension?

Could be the "unconscious" dimension -- see #5 above.

Today, I came across a very good web site by Cornell University (where Selden works), called "Ask An Astronomer", that answers a LOT of "typical" questions like we are asking here. The site is located at http://curious.astro.cornell.edu/index.php and has a search function on the left side. It truly is an amazing site to explore.

-Don G.

[Evil Dr Ganymede]

I haven't waded through the other thread, but if you're interested in this there's a very good book by Brian Greene called The Elegant Universe that explains a lot of this stuff nicely.

1. What is the basis for calling something a "dimension"?

Not sure of the exact definition, but I'd say a 'dimension' is one of a number of possible degrees of freedom of movement that exist in the universe, all at right angles to eachother.

2. Why is our physical universe considered to be 3 dimensions instead of ONE dimension, called "physical space", that simply has 3 "lines of movement" within it (up-down, left-right, forward-back) ... or FOUR dimensions (1-D point, 2-D line, 3-D plane, and 4-D cube)?

Because that's not how dimensions are defined . Forward-backward is one dimension, left-right is another, up-down is a third. The fourth dimension is at right-angles to all three of those (which is impossible for us to see in our 3D-space), the fifth is at right-angles to all of those four directions, and so on.

And it's a 0-D point, a 1-D line, 2-D plane, 3-D cube, and 4-D hypercube/tesseract. I dunno if the 5-D solid has a name . Points are zero-dimensional, since they have no width, length, or height.

3. If our 3 dimensions are based on measurements in different directions, then what about the "air" inside of a cube? We can measure that, so why isn't it called a dimension also?

Nope. It's simply something located in the cube. You can describe the location of any air molecule using 3 spatial co-ordinates and one temporal one (ie at 00:10 seconds, this molecule is at X,Y,Z co-ordinate in space)

4. Why is time considered to be a dimension, since it has no physical properties (particles, mass, energy, etc.), cannot be observed, etc.?

I'm not sure on this. It appears that there are both spatial dimensions and temporal dimensions. I suspect that time is really a type of spatial dimension that we can't comprehend fully because of our merely 3D existence and our primitive science . Why? It's just one of those things, I guess. Interestingly, a scientist called Max Tegmark attempted to model what the universe would be like with extra temporal and spatial dimensions, and have found that there are very few combinations that allow matter and energy to exist in the forms that we know them.

That said, it's definitely got a direction - past to future - so it qualifies as a dimension that way.

5. If time is considered to be a dimension simply because its effect can be measured, then why are conscious and unconscious not considered to be dimensions? The effects of both can be "measured", or indirectly observed, just like time, and are not limited to the brain function of human beings (intelligent life).

It's not. Time is a dimension because it has a direction. 'Conscious' and 'unconscious' are just biological states. They are not (as far as we know) properties of space-time.

6. Would it be possible that the expansion/acceleration of the universe is actually "causing" time to exist? When this expansion/acceleration stops, will time stop, creating eternity?

Dunno.

7. I keep reading that our universe is considered to be flat, but that word does not fit, since flat describes only a 2 dimensional plane. Our universe obviously has some thickness to it, so it should be called a cube in the shape of a square or rectangle, no? How thick is the universe? Is it a rectangular cube or a square cube (The Borg will love this one <snicker>)?

The Universe, as best as anyone can tell is an expanding 11-dimensional construct with 3 spatial dimensions, 1 temporal dimension, and the other 7 dimensions all curled up below the Planck length. It doesn't have a 'thickness' to it, unless you argue that the thickness is the size of the universe at the moment. "Flat" is a term that I suspect came out of how we visualise that - we're basically saying it has zero curvature.

8. Is there any "substance" (natural or man-made, sub-atomic, atomic, molecular, etc.) on Earth that resembles the construction of the universe -- great expanses of "something" (the vaccum) with sparse clusterings of mass and energy (galaxies) here and there?

I guess the closest one could get is the quantum foam that exists at the smallest scales. If anything can be called 'the fabric of the universe' it's that - a seething mass of virtual and real particles (and some argue entire universes) popping in and out of existence.

9. Why are the 4 "forces" not considered to be "dimensions"?

Because they have no direction. That said, I have heard some ideas suggesting that all the forces are just variations on the way things interact with space-time.

10. What do we expect to find in the warped or normal extra dimensions?

Nothing, as far as I know.

[selden]

I think one might consider aerogel to be an example of a substance with a physical structure somewhat analogous to the large scale structure of the universe. It does contain large voids and a very small amount of material surrounding them.

The Stardust cometary probe is using a sample capture device made of aerogel. See http://stardust.jpl.nasa.gov/tech/aerogel.html

[don]

Howdy Evil Dr. G.,

Thank you for your reply to my questions!

Thank you also for the book recommendation (The Elegant Universe).

For question #1 (What is the basis for calling something a "dimension"?), I found a good definition of what a "dimension" is at the Cornell "Ask an Astronomer" site. This question is answered here: http://curious.astro.cornell.edu/question.php?number=4...

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January 1999, Dave Kornreich

"Okay, the mathematical definition is something like, "The dimension of a manifold is the minimum integer number of co-ordinates necessary to identify each point in that manifold." A manifold is essentially a generic term for "area, volume, etc."

What this means in English is that a surface has, say, two dimensions, if you need two numbers to tell someone where you are on that surface. For instance, the surface of the Earth is two dimensional, because you need two numbers (usually longitude and latitude), to describe your position.

A line or the circumference of a circle is one-dimensional, since you only need one number (distance along the line; angle on the circle) to define where you are. The interior area of the circle is two-dimensional, since you need both angle and radius to define your position there.

You may have heard about chaos and fractal shapes. Fractal shapes are interesting because they can have non-integer dimension (hence "fractal"!). These non-integer dimensions are defined in a very complicated way somewhat different from what I have said above, but perhaps you can imagine a situation in which one number is not enough, but two is a little more than you need.


The above definition provides an obvious answer to question #2 (Why is our physical universe considered to be 3 dimensions instead of ONE dimension, ... or FOUR ...).

And it's a 0-D point, a 1-D line, 2-D plane, 3-D cube, and 4-D hypercube/tesseract. ... Points are zero-dimensional, since they have no width, length, or height.

Hmmmm, then the "point" (a dot) I can put on a piece of paper with a pencil is actually a line, and not a point at all. If a point has no dimensions (w, l, h), then it does not exist -- it is purely imaginary. I suppose that's why the pencil mark is called a "dot", or period, instead of a point. A "dot" has length and width, though you might need to get a microscope out to see it (ie. a "round" line).


Question #3 ... what about the "air" inside of a cube? We can measure that, so why isn't it called a dimension also?

You can describe the location of any air molecule using 3 spatial co-ordinates and one temporal one (ie at 00:10 seconds, this molecule is at X,Y,Z co-ordinate in space)

Riiiiight, now you're talking like the description of a dimension (above).


Question #4 ... Why is time considered to be a dimension ...

I'm not sure on this. ... Interestingly, a scientist called Max Tegmark attempted to model what the universe would be like with extra temporal and spatial dimensions, and have found that there are very few combinations that allow matter and energy to exist in the forms that we know them.

Not that this is a *limitation*, mind you, as there countless possible universes (exceeding 10^100) that can be created via string theory -- according to a New York Times Science article (http://www.nytimes.com/2003/09/02/science/space/02STRI.html?pagewanted=print&position=).

I don't particularly like the way Max Tegmark (or the article writers) spoke of 3+1 dimensions as being the only place where "life" or "intelligent life" can exist. That's as bad as saying that the Earth *is* the center of the solar system and the universe too. What an arrogant human being! Who cares if the "place" doesn't have *our* three physical dimensions? If there are 26 to pick from, then our three are certainly not that important, except to *us*.

Personally, I find residing in a physical, 3-dimensional body and universe, quite limiting, and would hope that there are some dimensions out there that don't have the three "physical" dimensions we do. For example, if a "thought" dimension existed, it would be much quicker to get anywhere than moving physically, it can take you anywhere, at any time, and you could not lie either. And, they would of course have their own additional dimensions, creating their own kind of universe, that they too would find "limiting" to get around in. Hmmm.

That said, it's definitely got a direction - past to future - so it qualifies as a dimension that way.

But, this does not meet the mathematical requirement for a dimension, as time is not a coordinate -- or is it? I guess maybe it is, because we can define an imaginary "point" anywhere along the past--to--future timeline, regardless if anything "exists" at that "point" in time.


Question #5 ... If time is considered to be a dimension simply because its effect can be measured, then why are conscious and unconscious not considered to be dimensions?

'Conscious' and 'unconscious' are just biological states. They are not (as far as we know) properties of space-time.

<snicker> In reply to your first sentence, I would argue against that statement purely because we really have no idea what conscious and unconscious are, other than they generate "states of human brain activity that can be measured". But, then in your second sentence, you correct yourself by adding "as far as we know" <smile>.

So, it is *possible* that conscious and unconscious could in fact be one or two of Fridgers "warped extra dimensions" that happen to be placed inside of all beings and objects (organic, mineral, etc.) that are capable of containing them. Pure wild speculation on my part, but nonetheless *possible*. <smile>


Question #6. Would it be possible that the expansion/acceleration of the universe is actually "causing" time to exist? When this expansion/acceleration stops, will time stop, creating eternity?

I would like to add this ... "It might also be the other way around, whereby *time* is causing the expansion / acceleration."


Question #7 ... I keep reading that our universe is considered to be flat, but that word does not fit, since flat describes only a 2 dimensional plane. ...

... we're basically saying it has zero curvature.

Okay, in this context it makes sense.


Question #8 ... Is there any "substance" (natural or man-made, sub-atomic, atomic, molecular, etc.) on Earth that resembles the construction of the universe ...

I guess the closest one could get is the quantum foam that exists at the smallest scales. If anything can be called 'the fabric of the universe' it's that - a seething mass of virtual and real particles (and some argue entire universes) popping in and out of existence.

Verrrrrrrry interesting! Here's something else I found about Quantum Foam, at (http://arxiv.org/PS_cache/physics/pdf/0307/0307003.pdf), that was just recently published. The abstract follows...

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June 2003
GRAVITY AS QUANTUM FOAM IN-FLOW
Reginald T. Cahill
School of Chemistry, Physics and Earth Sciences
Flinders University
Adelaide, Australia

The new information-theoretic Process Physics provides an explanation of space as a quantum foam system in which gravity is an inhomogeneous flow of the quantum foam into matter.

The older Newtonian and General Relativity theories for gravity are analysed. It is shown that Newtonian gravity may be written in the form of an in-flow. General Relativity is also analysed as an in-flow, for those cases where it has been tested.

An analysis of various experimental data demonstrates that absolute motion relative to space has been observed by Michelson and Morley, Miller, Illingworth, Jaseja et al, Torr and Kolen, and by DeWitte. The Dayton Miller and Roland DeWitte data also reveal the in-flow of space into matter which manifests as gravity. The experimental data suggests that the in-flow is turbulent, which amounts to the observation of a gravitational wave phenomena.

A new in-flow theory of gravity is proposed which passes all the tests that General Relativity was claimed to have passed, but as well the new theory suggests that the so-called spiral galaxy rotation-velocity anomaly may be explained without the need of ‘dark matter’. Various other gravitational anomalies also appear to be explainable. Newtonian gravity appears to be strictly valid only outside of spherically symmetric matter systems.


Question #9 ... Why are the 4 "forces" not considered to be "dimensions"?

Because they have no direction. That said, I have heard some ideas suggesting that all the forces are just variations on the way things interact with space-time.

I would think that forces do indeed have direction, or they would not be able to "force" anything anywhere. For example, gravity forces/pulls things "down".


Question #10 ... What do we expect to find in the warped or normal extra dimensions?

Nothing, as far as I know.

Then why bother creating them, exploring/probing them, etc.?

[don]

I think one might consider aerogel to be an example of a substance with a physical structure somewhat analogous to the large scale structure of the universe.

Ahhh yes, now I remember seeing this on TV, on a science show or on the news, a while back. I particularly remember the blow-torch demonstration!

Thanks Selden!

[don]

... there's a very good book by Brian Greene called The Elegant Universe that explains a lot of this stuff nicely.

And, a NOVA special by the same name, with Brian Greene hosting. It is scheduled to air on PBS October 28 and November 4 at 8pm (Eastern time I assume). Read more about it here: http://www.pbs.org/wgbh/nova/elegant/.

[Evil Dr Ganymede]

Howdy Evil Dr. G.,
Thank you also for the book recommendation (The Elegant Universe).

No prob. It's a very very good book. If you're as interested in this as you seem to be, you need to get it .

For question #1 (What is the basis for calling something a "dimension"?), I found a good definition of what a "dimension" is at the Cornell "Ask an Astronomer" site. This question is answered here: http://curious.astro.cornell.edu/question.php?number=4...

Yeah, what they said . I never could get my head around fractal dimensions though...

Hmmmm, then the "point" (a dot) I can put on a piece of paper with a pencil is actually a line, and not a point at all. If a point has no dimensions (w, l, h), then it does not exist -- it is purely imaginary. I suppose that's why the pencil mark is called a "dot", or period, instead of a point. A "dot" has length and width, though you might need to get a microscope out to see it (ie. a "round" line).

Ah, you're not thinking in abstract enough terms! If you look at it closely enough, a pencil point on paper is just fragments of graphite (or pen ink) on paper fibres, concentrated more toward the centre of the 'dot'. So a pencil dot really has width and length and depth on the scale of the paper fibres.

I think another, possibly better way for me to explain this is that a 0D-point is just a single co-ordinate in 4D space-time - it is at X,Y,Z at time T. A 1D-line is something that connects two points. A 2D plane is something that connects three points. A 3D solid is something that contains four or more points that are not in the same plane. And so on.



Question #4 ... Why is time considered to be a dimension ...

Not that this is a *limitation*, mind you, as there countless possible universes (exceeding 10^100) that can be created via string theory -- according to a New York Times Science article (http://www.nytimes.com/2003/09/02/science/space/02STRI.html?pagewanted=print&position=).

I don't particularly like the way Max Tegmark (or the article writers) spoke of 3+1 dimensions as being the only place where "life" or "intelligent life" can exist. That's as bad as saying that the Earth *is* the center of the solar system and the universe too. What an arrogant human being! Who cares if the "place" doesn't have *our* three physical dimensions? If there are 26 to pick from, then our three are certainly not that important, except to *us*.

Oh, it's not particularly a limitation - as you say there are practically an infinite variety of universes that can exist as a 3+1 space. I don't think we can really say that 'our' dimensions are the only ones. If we give length, width, height, and time the numbers 1,2,3 and 4 then I imagine it's quite possible for another universe to have dimensions 6,7, 8 and 9 and still be a 3+1 space.

Personally, I find residing in a physical, 3-dimensional body and universe, quite limiting, and would hope that there are some dimensions out there that don't have the three "physical" dimensions we do. For example, if a "thought" dimension existed, it would be much quicker to get anywhere than moving physically, it can take you anywhere, at any time, and you could not lie either. And, they would of course have their own additional dimensions, creating their own kind of universe, that they too would find "limiting" to get around in. Hmmm.

Now we're getting into metaphysics, which I'd rather not get into.

But, this does not meet the mathematical requirement for a dimension, as time is not a coordinate -- or is it? I guess maybe it is, because we can define an imaginary "point" anywhere along the past--to--future timeline, regardless if anything "exists" at that "point" in time.

Exactly. Time is another co-ordinate.

So, it is *possible* that conscious and unconscious could in fact be one or two of Fridgers "warped extra dimensions" that happen to be placed inside of all beings and objects (organic, mineral, etc.) that are capable of containing them. Pure wild speculation on my part, but nonetheless *possible*. <smile>

Yes, it's wild speculation . Again, this is getting into metaphysics. There's no evidence to suggest that we can access the folded dimensions, with or without technological assistance. Doesn't mean we can't or never will, but I find it better not to worry about it .


Question #8 ... Is there any "substance" (natural or man-made, sub-atomic, atomic, molecular, etc.) on Earth that resembles the construction of the universe ...

Verrrrrrrry interesting! Here's something else I found about Quantum Foam, at (http://arxiv.org/PS_cache/physics/pdf/0307/0307003.pdf), that was just recently published. The abstract follows...

Sounds bizarre! I've also heard some ideas that suggest that Inertia is basically resistance to moving through the quantum foam.

I would think that forces do indeed have direction, or they would not be able to "force" anything anywhere. For example, gravity forces/pulls things "down".

Forces act in a direction - they aren't directions themselves. They aren't spatial or temporal co-ordinates - they're vectors.

Question #10 ... What do we expect to find in the warped or normal extra dimensions?

Nothing, as far as I know.

Then why bother creating them, exploring/probing them, etc.?

Because their existence answers quite a few questions about why the universe is the way it is. Apparently the fixed physical constants of our universe - things like the gravitational constant, electromagnetic forces etc - have the numbers that they have because of the specific way those dimensions are folded into eachother. It's all explained rather well in that Elegant Universe book. Fascinating stuff.

[t00fri]

4. Why is time considered to be a dimension, since it has no physical properties (particles, mass, energy, etc.), cannot be observed, etc.?

First of all...

It turns out that Einstein's 2 basic principles of special
relativity can be elegantly realized by going from 3
spacial to 4 space-time dimensions. Instead of 3-vectors
{x,y,z} one thus considers 4-vectors {ict,x,y,z}, with i = sqrt(-1),
c = speed of light and t = time.

Why will some of you ask...Here comes the essence of it:

Einstein's 2 basic principles of special relativity read (remember?):

1) Relativity principle: All inertial coordinate systems are
equally good for describing processes/events in Nature.

2) Constancy of the speed of light: In all inertial systems, the
speed of light in the vacuum = c has the same value in all
directions and independent from the motion of the light source!


Notably 2) is equivalent (homework?) to saying that the length of any
4-vector in two inertial systems O and O' has to be the same, i.e

x^2 + y^2 + z^2 + (ict)^2 = x'^2 + y'^2 + z'^2 + (ict')^2

The solution of this equation gives the familiar Lorentz transformation
laws (<=> length contractioon, time dilatation) between two such systems...


Moreover...

Our beautiful quantum field theory that is so well verified in Nature,
is invariant under Lorentz transformations of special relativity,
and comprises the so-called Standard Model, looks entirely symmetrical
and most elegant in this 4-dimensional formulation!

Finally...

The formulation and structure of this theory would NOT change, if we
would extend it from 4 to an arbitrary number of space-time
dimensions!

An accident? Noooooooooooooooooooooooooooooooooooo

Bye Fridger

[t00fri]

Oh, after checking again, I noticed that Evil Dr. G. quoted Brian Greene a string theorist from Columbia U., while I thought/misread that he was referring to Mike B. Green (Queen Mary C., London). While I don't know Brian G. personally, I do know Mike B. G.

Mike Green is one of the fathers of Superstring theory! So any book you can get hold of by him is certainly worth reading.

He and I actually overlapped for 2 years, when we both were young scientists, working at the international laboratory CERN in Geneva/Switzerland, where I stayed for seven years altogether...

It was at that time at CERN, when he and John H. Schwarz (Caltech) wrote their famous paper that started the "first Superstring revolution". In short, strings were quite popular at the time as an elegant description for the strong interactions of "hadrons", i.e. protons, pions etc...

Mike G. and John Sch. noticed that this very same theory could describe also gravitation besides the normal interactions, if only one dared to change the intrinsic energy scale from the proton mass to the Planck mass, i.e. upwards by 19 orders of magnitude!!!

And they noted another crucial benefit of this procedure:

The "old string theory" for hadrons was always formulated in 3+1=4 dimensions (what else?;-)), which implied that one light hadron, the familiar Pion turned inevitably out to be a tachyon in string theory, which was of course horrible.

In this famous paper, it was also recognized that the "new string theory" would be perfectly consistent (i.e. free of tachyons) if it was formulated not in 4 but in 10 dimensions!!

Mike Green once told me over a cup of coffee in the CERN cantine that they wrote that paper as sort of a joke...Well jokes are not always jokes;-)

Bye Fridger

[don]

If you're as interested in this as you seem to be, you need to get it .

I will, for sure.

I never could get my head around fractal dimensions though...

It does sound a bit odd, but sure produces some great art pieces!

Ah, you're not thinking in abstract enough terms! If you look at it closely enough, a pencil point on paper is just fragments of graphite (or pen ink) on paper fibres, ...

Okay, now I see how a dot would actually be considered 3-D and not just 2-D. Thanks.

If we give length, width, height, and time the numbers 1,2,3 and 4 then I imagine it's quite possible for another universe to have dimensions 6,7, 8 and 9 and still be a 3+1 space.

Using the 3+1 term, I meant our three physical dimensions (length, width, and height) plus time. Of the 26 or so dimensions that may exist, are any of them calculated to be duplicates? For example, if #4 is our time dimension, could any of the remaining dimensions also be a "time" dimension just like ours?

Now we're getting into metaphysics, which I'd rather not get into.

Oh <sigh>. Why is it that it is easy for a physicist to talk about strong and weak "forces", which can not be directly observed (just like human consciousness), as one can only measure their "effect" (or mathematically calculate it), and they can easily combine these imaginary "forces" with other mathematical things to create and or interact with particles, all the way up to cosmological scales, extra dimensions, 10^100 possible universes, etc. ... but when organic "things" (human beings for one example) are brought into the picture, all of a sudden it becomes "metaphysical", or "spiritual", or "religious", or whatever, and they don't want to have anything to do with it?

At some point in time, physics is gonna have to combine with the organic sciences in order to fully describe a human being, or any other life form that has thoughts, feelings, intelligence, etc. We are not merely atoms and molecules, as there are also "forces" or "energy" in us (conscious, unconscious, good, evil, spirit, soul, Chi, or whatever one wants to call them) that have nothing to do with "particles", that no "scientist" wants to go near. Why?

It just seems very odd to me. Are these things simply beyond our scientific ability to comprehend, explain, observe, test, put into mathematical form, or whatever? Since we are here in 3-D plus time, there is obviously a string or other theory scenario that allows a "connector" between physical dimensions and non-physical dimensions. So, why can't the math show what other non-physical dimensions should be available and look for other connectors? Why is all of this being left to Psychology, which appears to have gone nowhere since Freud? It would seem that they could USE a few good Physicists to get them stirred up by bringing forces and other quantum "stuff" into the organic realm <smile>!

Exactly. Time is another co-ordinate.

Then, it follows that we should be able to traverse it in both directions, and not only in one direction. But, since we cannot, that was the thought behind my earlier question of thinking that time might in some way be connected to the acceleration (forward motion) of the universe. Time might in fact be one of the warped extra dimensions but we are only able to "observe" one or two of it's tangents -- the forward motion of time and the expansion of the universe, but *not* the backward motion of time.

I've also heard some ideas that suggest that Inertia is basically resistance to moving through the quantum foam.

I would think this would only be valid for the "at rest" state, and not the "in motion" state (ie. a tool thrown in outer space keeps moving), no?

Forces act in a direction - they aren't directions themselves. They aren't spatial or temporal co-ordinates - they're vectors.

Ahhh, I got it. Thanks.

Thank you for your helpful answers and stimulating conversation, Evil Dr Ganymede!

[t00fri]

7. I keep reading that our universe is considered to be flat, but that word does not fit, since flat describes only a 2 dimensional plane. Our universe obviously has some thickness to it, so it should be called a cube in the shape of a square or rectangle, no? How thick is the universe? Is it a rectangular cube or a square cube (The Borg will love this one <snicker>)?

Flatness here means a geometry where

1) two parallel straight lines intersect at infinity
2) the sum of the angles in a triangle is 180 degrees

as simple as that...

Bye Fridger

[selden]

Now we're getting into metaphysics, which I'd rather not get into.

Oh <sigh>. Why is it that it is easy for a physicist to talk about strong and weak "forces", which can not be directly observed (just like human consciousness), as one can only measure their "effect" (or mathematically calculate it), and they can easily combine these imaginary "forces" with other mathematical things to create and or interact with particles, all the way up to cosmological scales, extra dimensions, 10^100 possible universes, etc. ... but when organic "things" (human beings for one example) are brought into the picture, all of a sudden it becomes "metaphysical", or "spiritual", or "religious", or whatever, and they don't want to have anything to do with it?

The whole point of the scientific method is that it's concerned with "what", not with "why".

By this I mean, it is a way to investigate the things we see happening and to use the things we see to predict what else will happen under somewhat different circumstances.

The scientific method does not assign "intent" to events. It only describes them. The rock does not intend to roll down the hill. Instead, it's a consequence of the molecular forces holding the dirt in a barrier around it being less than the rock's potential energy.

I do think the Evil One was misusing the term "metaphysics", though. If we could find a way to measure "thought" of the kind you're describing in some consistant way, then it would become the object of scientific investigation.

At some point in time, physics is gonna have to combine with the organic sciences in order to fully describe a human being

That's called biophysics.

or any other life form that has thoughts, feelings, intelligence, etc. We are not merely atoms and molecules, as there are also "forces" or "energy" in us (conscious, unconscious, good, evil, spirit, soul, Chi, or whatever one wants to call them) that have nothing to do with "particles", that no "scientist" wants to go near. Why?

Because the things you name cannot be measured in any consistant way. We have no way to measure Chi. The scientific method requires that we be able to observe it (measure it) in ways which allow for unambiguous predictions.

Right now the most consistant description that I've seen is that they're stories that we tell ourselves to explain our emotional reactions. They're very pleasant fictions.

Of course, there are some things being learned about some of the chemical and biological causes of some kinds of emotional states, but a lot of people don't like to hear them.

Also, remember that our understanding of the chemical reactions of many biological reactions is still very rudimentary. The processes are incredibly complex. Particle physics is simple in comparison. For example, there are thousands of atoms in the protein that moves potassium atoms one at a time through the membrane of a cell.

There are even more complex molecules involved in life processes that we can't even begin to investigate yet. Our current methods of looking at them (x-rays from synchrotrons) damages them so quickly that it's hard to get a snapshot of them as crystals, let alone watch them in action.

[Evil Dr Ganymede]

Well, perhaps I did use 'metaphysics' a bit too broadly. 'Philosophical' might have been a better term?

The problem is that science is built to be objective and its hypotheses provable by repeated, rigorous experimentation. So anything that depends solely on one's beliefs or opinions, or that can't be proven to exist by repeated experimentation is by definition outside of science. (that's probably over-simplifying things, admittedly).

So things like psychic abilities, out of body experiences, ghosts, the afterlife, Heaven/Hell, God etc can't as yet fit in the scientific paradigm, though some of those things are getting close.

I'm open-minded about most of those things though - any good scientist should be IMO. But things like religion and spirituality are based solely on faith, not hard evidence. Science can't prove or disprove God, but it seems more reasonable to me that God doesn't exist. Doesn't mean I'm right though - that's just my opinion, based on the available evidence. Then again, it doesn't mean that a devout bishop is right to say that God exists either... but even if he's wrong he doesn't have to care about that, because he has his faith. He believes God exists, he sees God everywhere, so for him, he exists. He says "Look at the glory of God all around us!", I say "Look at the wonder of the life and planets and stars and galaxies all around us!". He sees God's hand in everything, I see the amazing clockwork of the physical laws of the universe. But neither of us is going to persuade the other that we're right - I can prove I"M right, and the bishop can prove (in his own way) that HE's right, but we have totally distinct, utterly incompatible views of reality. At best, we can agree to disagree. At worst, one of us will put the other to death for being a 'heretic' or a 'traitor to reason' .

You believe that there are forces and energies and souls inside us. I don't... though I'm not saying that there AREN'T any such forces, I'm not going to assume that they're there either, and I'm not going to say that you're wrong. I've not seen enough evidence for such things to satisfy me, though I've seen plenty of things that give me reason to believe that our understanding of the universe is incomplete (not to mention that it would be incredibly 'hubristic' to believe that science can explain everything at this stage). I've seen some pretty wacky things in my time... people punching through huge concrete blocks on a stage in front of me from only a couple of inches away in martial arts demonstrations (apparently by focussing Chi), and some amazing illusions that I STILL can't figure out (A David Copperfield show in Vegas. The illusion where he gets cut in half by a huge bandsaw. I'd seen that on TV and had been amazed, and I made a point of looking for ANYTHING that he could have done to not really get sawn in half, but I couldn't see anything even when he did it about 20 ft in front of me. I still can't figure out how he did it). I think there is a lot that we don't understand about the universe. I think there is a lot we don't understand about our own minds and bodies. It may all be a mystery now, it may all be 'magic', or 'spiritual' but eventually I think our scientific paradigm will expand to encompass the things we don't understand yet. I hope it does, anyway. But when it does, I think that the new paradigm that we use to describe the universe will be rather different to the scientific paradigm we use today.

Basically, I agree with you - there is still much we don't understand. It's just that right now (as indeed, in the past) people tend to get very passionate about the things they believe in, and I don't want to get embroiled in huge arguments about such things. Belief is a personal thing, Science is a more 'external' thing that everyone has in common and can talk about on the same level. So I prefer the latter .

OK. That was all pretty philosophical and metaphysical. Sorry .

[don]

Howdy Fridger,

4. Why is time considered to be a dimension, since it has no physical properties (particles, mass, energy, etc.), cannot be observed, etc.?

... Instead of 3-vectors {x,y,z} one thus considers 4-vectors {ict,x,y,z}, with i = sqrt(-1), c = speed of light and t = time.

Square Root of -1?, or sqrt of *something* times -1?

The solution of this equation gives the familiar Lorentz transformation
laws (<=> length contractioon, time dilatation) between two such systems ... Standard Model ... The formulation and structure of this theory would NOT change, if we would extend it from 4 to an arbitrary number of space-time dimensions!

I think I understand what you wrote, but I don't understand how what you wrote defines time as a dimension. Are you saying, "time is considered to be a dimension because it fits into mathematical formulae."?

Would no other 4th vector "fit"? If not, then "time" by itself is not considered to be the 4th dimension, but rather ict as you described above, correct?

-Don G.

[don]

Mike Green is one of the fathers of Superstring theory! So any book you can get hold of by him is certainly worth reading.

Thanks Fridger!

It was at that time at CERN, when he and John H. Schwarz (Caltech) wrote their famous paper that started the "first Superstring revolution".

Those must have been exciting times for you, not to mention the other two guys!

Mike G. and John Sch. noticed that this very same theory could describe also gravitation besides the normal interactions, if only one dared to change the intrinsic energy scale from the proton mass to the Planck mass, i.e. upwards by 19 orders of magnitude!!!

Hmmmm, 10^19 sounds familiar ... wasn't that the huuuuuuuuuge number you wrote in an earlier post, that is creating problems for physicists?

In this famous paper, it was also recognized that the "new string theory" would be perfectly consistent (i.e. free of tachyons) if it was formulated not in 4 but in 10 dimensions!! Mike Green once told me over a cup of coffee in the CERN cantine that they wrote that paper as sort of a joke...

A joke?! Sheesh, guess it REALLY backfired!

Why didn't they get laughed out of existence for bringing up such a FICTIONAL topic: SIX additional dimensions? I mean, they might as well have said they discovered how to produce negative gravity.

-Don G.

[don]

7. I keep reading that our universe is considered to be flat, but that word does not fit, since flat describes only a 2 dimensional plane. ...

Flatness here means a geometry where

1) two parallel straight lines intersect at infinity
2) the sum of the angles in a triangle is 180 degrees

This is exactly how the "Ask an Astronomer" site at Cornell answered the question.

Thanks Fridger!

-Don G.

[don]

... but when organic "things" (human beings for one example) are brought into the picture, all of a sudden it becomes "metaphysical", or "spiritual", or "religious", or whatever, and they don't want to have anything to do with it?

The whole point of the scientific method is that it's concerned with "what", not with "why".

Howdy Selden,

Yes, I know this. I don't think I asked "why", except ... why scientists exclude the study, measurement, etc. of whatever "forces" and/or "energies" exist within (or without I guess) organic "things" (like humans). That is a "why not" question.

The scientific method does not assign "intent" to events. It only describes them.

I understand this also. I was asking why science has not, or does not want, to investigate, study, theorize, discuss, describe forces / energies relating to organic things -- mainly humans.

If we could find a way to measure "thought" of the kind you're describing in some consistant way, then it would become the object of scientific investigation.

Sorry, but I disagree. We don't have any way to "measure", or otherwise prove, a great many of the theories that already exist. But, they certainly are being studied / investigated.

We (the human race) are spending billions upon billions of dollars / yen / pounds / etc. to build particle accelerators/colliders, rocketships, space and planetary probes, space-based telescopes, observatories, space stations, etc., in order to "test" some of the previously published theories, as well as to explore the unseeable things in our universe (small and big).

BUT, how much is being spent on studying, testing theories, or exploring new things relating to organic life, especially humans? A mere pittance, compared to other sciences.

Here we are with a mostly complete human genome (99.99% I think?), but it only defines the molecular structure of a human being, and does not include any information about whatever else resides in / on / around a human being. Now, some idiot scientists say they are ready to start cloning humans? I mean ... give me a bareak palease! ... That sounds like cloning an automobile but leaving out the required fuel supply and storage tank that allows it to *run*!

That's called biophysics.

Well then, let's start funding biophysics like some of the other sciences, and start learning something about the non-physical attributes of organic life -- including ourselves -- human beings!

Because the things you name cannot be measured in any consistant way. We have no way to measure Chi. The scientific method requires that we be able to observe it (measure it) in ways which allow for unambiguous predictions.

Gong. Wrong answer.

There are hundreds (dare I say thousands) of "scientists" from the past and present, who were/are not in the least bit able to measure or observe what they have in fact created mathematical equations and formulae, theories, and even written papers for. What we are discussing in this thread and other threads here in the Physics & Astronomy forum, are exactly these things! Warped extra dimensions, string theory, multiple universes, etc.

Not a single one of these things was observed or measured in order to "allow for unambiguous predictions" before the theories (unambiguous predictions) were published. These people simply *thought* something in their brain, mulled it around, worked on mathematical formulae to give their "thoughts" a math-based foundation (when possible), and then put the "thought" forth as a theory. Sooooo, why hasn't this been done in the biophysics realm?

Also, remember that our understanding of the chemical reactions of many biological reactions is still very rudimentary.

You are talking about "physical" organic / biological properties, but I am talking about the non-physical properties

I am trying very hard to keep religion-based and New Age words and terms out of this discussion because they are based on belief, not proof. And, I am trying to use other words (force, energy, conscious, unconscious, etc.) for these non-physical properties, that can indeed be experienced, observed, and even measured in some ways.

But, sometimes I cannot think of an appropriate word to use, and resort to the religion-based word/term such as Chi, which is a single word to describe a complex energy field that is intermingled with a human being, according to Chinese "beliefs".

After all of this, my question still remains: Why do scientists seemingly not want to explore the non-physical properties of organic life, including human beings, or even try to create better instruments to measure these properties? Do scientists "believe" that organic life has no energy or force, aside from that created by internal chemical reactions and biological processes? I say "believe" because it certainly cannot be proven, or disproven, either way.

Food for thought,

-Don G.

[don]

The problem is that science is built to be objective and its hypotheses provable by repeated, rigorous experimentation. So anything that depends solely on one's beliefs or opinions, or that can't be proven to exist by repeated experimentation is by definition outside of science.

I am trying to keep "religion" out of this discussion by not talking about "religious beliefs", religion, or New Age stuff.

We can all directly observe that organic life is either alive (contains energy) or dead (does not contain energy), or is awake (conscious) or sleeping (unconscious). We are also able to measure some things (brain waves and activity for two) relating to the conscious and unconscious state of organic life, via the brain of the subject. I'm not talking about a "mental" state here, but the basic organic states of life/death, and awake/sleeping.

So things like psychic abilities, out of body experiences, ghosts, the afterlife, Heaven/Hell, God etc can't as yet fit in the scientific paradigm, though some of those things are getting close.

Sorry, but I don't recall mentioning any of these things in this thread. Here is the portion of my post that everyone seems to be replying to:

Code: Select all

Why is it that it is easy for a physicist to talk about strong and weak "forces", which can not be directly observed (just like human consciousness), as one can only measure their "effect" (or mathematically calculate it), and they can easily combine these imaginary "forces" with other mathematical things to create and or interact with particles, all the way up to cosmological scales, extra dimensions, 10^100 possible universes, etc. ... but when organic "things" (human beings for one example) are brought into the picture, all of a sudden it becomes "metaphysical", or "spiritual", or "religious", or whatever, and they don't want to have anything to do with it?

At some point in time, physics is gonna have to combine with the organic sciences in order to fully describe a human being, or any other life form that has thoughts, feelings, intelligence, etc. We are not merely atoms and molecules, as there are also "forces" or "energy" in us (conscious, unconscious, good, evil, spirit, soul, Chi, or whatever one wants to call them) that have nothing to do with "particles", that no "scientist" wants to go near. Why?

It just seems very odd to me. Are these things simply beyond our scientific ability to comprehend, explain, observe, test, put into mathematical form, or whatever? Since we are here in 3-D plus time, there is obviously a string or other theory scenario that allows a "connector" between physical dimensions and non-physical dimensions. So, why can't the math show what other non-physical dimensions should be available and look for other connectors? Why is all of this being left to Psychology, which appears to have gone nowhere since Freud? It would seem that they could USE a few good Physicists to get them stirred up by bringing forces and other quantum "stuff" into the organic realm <smile>!


Please note this part: "... but when organic "things" (human beings for one example) are brought into the picture, all of a sudden it becomes "metaphysical", or "spiritual", or "religious", or whatever, and they don't want to have anything to do with it?"

I said "organic 'things'", and used humans as one example. There are many other organic "things" (life forms) on our planet, that have demonstrated, and which we can directly observe, the state of being alive or dead, certain levels of "intelligence", consciousness, etc. But, when trying to discuss or attempt to theorize what the "life force" (what makes organic life alive or dead), or conscious, or unconscious, etc. of organic life might be, everyone (including scientists around the whole world) all of a sudden jump to the conclusion that the person is talking about religion, and personal beliefs. Grrrrrr, this is maddening!

If I happen to use a religious term, it is because I cannot determine what other word to use, or there is no other word in the English language. What word would a scientist use to describe what makes an organic life form alive or dead? Energy, force, Chi, chemical reactions, biological processes, or something else? No, of course not. They simply dismiss the thought as being "religious" in nature, knowing full well that organic life forms do not have any kind of "life force" (even though it can't be proven either way), then proceed to dismiss the person and the conversation <laughing>! And this is the way it seems to have been since time started.

Science can dream about, theorize and mathematicize the entire physical universe (or 10^100's of universes, along with 26 dimensions), from the first millisecond it appeared, to the end of it's existence, and everything in between. But, ask a question like "what gives organic life it's life?", and science runs the other way laughing. What have I missed?

But things like religion and spirituality are based solely on faith, not hard evidence.

Which is exactly why I'm trying very hard to keep them OUT of this discussion, but everyone else seems to be bringing them in! Why?

I don't call Fridger's "belief" or "faith" in extra dimensions "religious or "spiritual". So, why should anyone call my belief that organic life forms have *something* in / on / around them that causes them to be alive or dead, as having anything to do with "religion and/or spirituality"? This makes no sense.

You believe that there are forces and energies and souls inside us. I don't.

Just as Physicist A believes the string theory, while Physicist B does not. However, these differing "beliefs" do not stop other physicists from thinking about, contemplating, theorizing, playing with numbers and formulae, etc. relating to the string theory, and all associated matters. And, Physicist A is certainly not condemned as being "religious" or one who has "faith" or "beliefs" in something that cannot be seen, measured, or proven. It has nothing to do with religion.

So, why is the "belief" that organic life forms have something in / on / around them that gives them "life", so different? This has nothing to do with religion either. It is a scientific question, or theory if you prefer, that has a PHYSICAL and OBSERVABLE basis behind it (life and death of organic life forms).

We can't "see" time, but we can measure it. We can't "see" life, but we can observe it. What's the difference?

But when it does, I think that the new paradigm that we use to describe the universe will be rather different to the scientific paradigm we use today.

Of this, I have no doubt! ... We have seemingly limited ourselves to exploring only the physical (sub-atomic, to cosmic) part of our universe, leaving the non-physical parts completely UNexplored. The best example of this would probably be time. It has not been explored in the least, except mathematically and by Science Fiction writers, even though it has been proven to exist. Why not?

If there are supposed to be 10 dimensions in our universe, according to string theory, and we have only observed four, the first scientific human reaction is to make the other dimensions go away because they don't fit the mathematical model, so let's just curl them up into microscopic points, completely out of sight and mind. Why? Just because we cannot observe or measure them? Why are there no theories to explain what these other dimensions might contain? Or that they might actually exist right here and now, but we simply cannot observe or measure them to "prove" their existence? Instead, we hide them in our formulae, give them imaginary values that fit our mathematical models, and go about our "scientific" business as if we didn't just perform our own form of "magic".

I'm not condemning scientists. I am condemning the process of science, to a point, where if something doesn't fit, hide it, make it go away, ignore it, whatever, instead of trying to explain it, theorize it, measure it, test it, etc. This reminds me of a three year old kid throwing all his toys under the bed and saying, "My room is all clean now!"

To summarize this reply (three cheers, right?), this thread has nothing to do with religion, God, religious beliefs, etc. What it does have to do with is a scientific question ... why do scientists "run the other way laughing" when someone wants to discuss the thought (theory) that organic life forms have something that makes them alive, versus dead -- like electricity being applied to an electrical circuit?

The answer appears to be: "Because we believe in, and have faith in, without any proof, the theory that organic life forms only have chemical reactions and biological processes to make them alive or dead, and refuse to theorize that anything else (other dimensions) could even remotely be possible."

This just seems way too "close minded", and like "religious fanaticism" to me. ... Which begs the question, "In certain matters, has science become it's own religion?"

-Don G.