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John Kierein
2002-Apr-05, 06:30 PM
The book is finally out.
http://shop.alpmicro.com/apeiron/

Phobos
2002-Apr-05, 06:48 PM
Hi John,

You might find my recent posting interesting. Its purely wild speculation, but I propose that if a parallel planet Earth in a parallel universe was gravitationally locked with our planet, then it may be possible to "view" the objects on that planet by examining micro gravitational descrepancies on this one.

Phobos

<font size=-1>[ This Message was edited by: Phobos on 2002-04-05 13:49 ]</font>

John Kierein
2002-Apr-05, 07:59 PM
I'm not a big believer in multiple dimensions. While it takes more than just 3 dimensions to describe an object, they aren't all necessarily the same. For example I can say where your car is in 3 dimensions. But I can specify it better if I tell you when it is at the 3D location. I can further specify it better if I tell you what it's velocity is at that place and time. I could further describe it better by saying what its acceleration is at that place, time and velocity. Also I could even further specify it by saying what its rate of change of acceleration is. Etc.,etc. I could also specify it better by saying what color it is, or how bright it is, etc. Are all these specifications dimensions? You could plot the location in in space, time, velocity, acceleration, color spectrum, brightness level, etc, to look for it as a target. But I'll claim that these aren't "true" or "basic" dimensions. Velocity, acceleration ,etc. can be expressed in terms of rates of change of the basic three. So they are "derived" dimensions. Color, brightness, etc. aren't really dimensions in my book. Even time can be argued to be a measure of change in the basic three and thus be derived. So I am tempted to disagree with Einstein's placing time on the same level as the 3 spatial dimensions. In my example of your car, the car has a non-zero 3d spatial dimension, but may have a zero velocity, acceleration etc. Now if an object is in another dimension, but is NOT in our 3D universe (i.e., the static 3 dimensions are zero), I don't think we can sense it. So it must have zero mass for us and no gravitational effect. If it has mass, I think it must have 3 dimensionality and so we could sense it.
Anyhow that's my opinion. I guess I'm no fun at all.

Phobos
2002-Apr-05, 08:39 PM
The idea of higher spacial dimensions is still under consideration - eg.

Science News Online Article (http://www.sciencenews.org/20000219/bob1.asp)

String theory dictates that any extra dimensions outside a brane affect only gravity. In other words, just the force-carrying particles of gravity, called gravitons, could travel in the space-time beyond the brane, leaving the other forces confined to the brane. By contrast, extra dimensions associated with the brane influence all the forces.
So if there are higher dimensions, then the idea of gravity from higher dimensions causing an effect in our 3 is not totally unrealistic.

The article includes the following link to an archieved study by CERN theorists Keith R. Dienes, Emilian Dudas, and Tony Gherghetta;
Extra Spacetime Dimensions and Unification (http://xxx.lanl.gov/abs/hep-ph9803466)

Of particular interest is the following quote;

Furthermore, we show that extra spacetime dimensions provide a natural mechanism for explaining the fermion mass hierarchy
Phobos

<font size=-1>[ This Message was edited by: Phobos on 2002-04-05 16:31 ]</font>

John Kierein
2002-Apr-06, 09:50 AM
I don't think that, even if there are higher dimensions, that the basic 3 dimensions can be zero. In other words if an object has 10 dimensions, it MUST include the first 3. Thus, any massive object must have 3 dimensions and if we see its gravity we must see its 3 dimensionality. So I doubt that there are parallel earths lacking 3 dimensionality that we could feel their gravitational aspects. In some theories of gravity, you might feel some aspect of gravity that is due to some higher dimensionality (like my treatment of velocity as a higher dimension for example), like a bunching up of the digitization of gravity forces (gravitons) in the forward direction of a mass moving at high velocity; but the mass must have 3 dimensionality and not be a parallel object.

2002-Apr-06, 12:11 PM
On 2002-04-06 04:50, John Kierein wrote:
I don't think that, even if there are higher dimensions, that the basic 3 dimensions can be zero. In other words if an object has 10 dimensions, it MUST include the first 3. Thus, any massive object must have 3 dimensions and if we see its gravity we must see its 3 dimensionality. So I doubt that there are parallel earths lacking 3 dimensionality that we could feel their gravitational aspects. In some theories of gravity, you might feel some aspect of gravity that is due to some higher dimensionality (like my treatment of velocity as a higher dimension for example), like a bunching up of the digitization of gravity forces (gravitons) in the forward direction of a mass moving at high velocity; but the mass must have 3 dimensionality and not be a parallel object.

6:02 A.M. already over my online time limit of

1 hr at 1hr 3 so later 4 this1 2

4-Lom
2002-Apr-08, 10:07 AM
String theory proposes that space is made of 10 or 26 dimensions, and that in the 10 dimensional case, 6 dimensions are cyclic and curled up so that they're length is well under planck length. No earthly devices produce anywhere near enough energy to probe these scales. However these extra dimensional 'spaces' allow previously un-unitable forces to become united. And it all works spookily well.
I think Edward Witten said that the human race doesn't deserve String Theory yet. We have the theory, but we dont have the intelligence or tools to figure it out. I love string theory!

4-Lom
2002-Apr-08, 10:13 AM
So I am tempted to disagree with Einstein's placing time on the same level as the 3 spatial dimensions. In my example of your car, the car has a non-zero 3d spatial dimension, but may have a zero velocity, acceleration etc. Now if an object is in another dimension, but is NOT in our 3D universe (i.e., the static 3 dimensions are zero), I don't think we can sense it. So it must have zero mass for us and no gravitational effect. If it has mass, I think it must have 3 dimensionality and so we could sense it.
Anyhow that's my opinion. I guess I'm no fun at all.

Read more about Einstein, and you will realise that time is a definate dimension. Everything is moving at the speed of light all the time, but the velocity (energy) is in different directions with respect to time. So if you are still, you are travelling at light speed through time. If you are travelling at light speed in space, you can have no time component, and hence time stands still. Thats why time and space distort as you increase in speed, you are just spreading your E component in different dimensions. Thats a bit over-simplified but it explains the general principle.

John Kierein
2002-Apr-16, 05:38 PM
http://www.magna.com.au/~prfbrown/news99_b.htm

DStahl
2002-Apr-17, 03:26 AM
Superstrings are, in some representations, 1-dimensional objects. Heck, in the standard model electrons and quarks are treated as point particles with no dimensions, yet they have mass. (One could argue that mathematical points can't exist as particles because Professor Heisenburg grants them Planck-scale size...)

Anyway:

1. Hypothesis: a non-dimensional point cannot have mass, ie its mass must equal 0.

2. Corollary: a one-dimensional line is nought but an extension of no-dimensional points through N repetitions, and since N X 0 = 0 then a one-dimensional line cannot have mass.

3. Corollary: a two-dimensional plane or surface is nought but an extension of one-dimensional lines through N repetitions, and since N X 0 = 0 then a two-dimensional plane cannot have mass.

4. Corollary: a three-dimensional volume is nought but an extension of etc. etc. and since N X 0 = 0 it can't have mass either.

Bah. The initial hypothesis must be incorrect.

--Don "naive argument" Stahl

SeanF
2002-Apr-17, 12:19 PM
On 2002-04-16 23:26, DStahl wrote:

2. Corollary: a one-dimensional line is nought but an extension of no-dimensional points through N repetitions, and since N X 0 = 0 then a one-dimensional line cannot have mass.

This corollary is logically flawed, as it relies on two contradictory "givens":

1) A line is an extension of non-dimensional points through N repetitions

2) Nx0 = 0

If the second statement is true, then an extension of non-dimensional points would have a length of Nx0, and if that's 0 then the extension is still non-dimensional, and it's not a line.

Since this corollary is flawed, so are the ones that follow from it.

I think the point being missed is infinity. A line is an extension of points through infinite repetitions (no matter how short the line is), and infinity x 0 <> 0.

Basically, if you accept that zero-length points can be stacked together to produce a non-zero length, then you must accept that zero-mass points can be stacked together to produce a non-zero mass.

John Kierein
2002-Apr-17, 12:20 PM
Ah, but the reverse is not necessarily so. A 3 dimensional space may not have mass, but a mass must occupy a 3 dimensional space. The "treatment" may well be wrong. An extended object can be "treated" as though it's mass were all at the center of mass, but that is only good for masses of constant density. A lumpy object has distortions to this as evidenced by the discovery of "mascons" on the moon. The GRACE mission is another case in point.

GrapesOfWrath
2002-Apr-17, 01:19 PM
On 2002-04-17 08:20, John Kierein wrote:
An extended object can be "treated" as though it's mass were all at the center of mass, but that is only good for masses of constant density.

Spherically symmetric density is OK too--in fact, objects of constant density also fail if they are not spherical.

DStahl
2002-Apr-17, 06:38 PM
Yeah, the argument above is both naive and simplistic. I really didn't imagine it would go anywhere.

But I have my doubts about the idea that only a 3-d volume can possess mass. Can a point electrical charge exist? Physics treats electrons as such. Why not a point mass, then? Is the idea of mass tied to mensurable volume intuitional--ie tied to the intuition that if we decrease the volume of everyday objects (without messing with their densities) their mass decreases proportionally, logically arriving at 0 mass for 0 volume...or is there a deep reason in physics why a point particle cannot have mass? A lot of quantum physics in emphatically not intuitional, ya know...

--Don Stahl

John Kierein
2002-Apr-17, 09:28 PM
A point mass would be of infinite density. It would be denser than a black hole. I'm not a big believer in black holes myself.

Zandermann
2002-Apr-17, 09:37 PM
... I'm not a big believer in black holes myself.Ah...but the *real* question is: do they believe in you?

/phpBB/images/smiles/icon_smile.gif

John Kierein
2002-Apr-18, 12:54 PM
The big trouble with a point mass with no dimensions, is that if it gets inside something the gravitational force becomes infinite. As R goes to zero the force goes to infinity. If there were such things we'd all be crushed. An infinite force is bigger than the force from a black hole.

Silas
2002-Apr-18, 01:35 PM
On 2002-04-18 08:54, John Kierein wrote:
The big trouble with a point mass with no dimensions, is that if it gets inside something the gravitational force becomes infinite. As R goes to zero the force goes to infinity. If there were such things we'd all be crushed. An infinite force is bigger than the force from a black hole.

Don't the same objections apply to any point-source, such as an electron? At zero distance, the electric field is infinitely dense... The answer is that nothing gets within zero distance...

I see what you mean, of course, but "common sense" stops working at these sorts of scales...

Silas

ToSeek
2002-Apr-18, 02:58 PM
On 2002-04-18 08:54, John Kierein wrote:
The big trouble with a point mass with no dimensions, is that if it gets inside something the gravitational force becomes infinite. As R goes to zero the force goes to infinity. If there were such things we'd all be crushed. An infinite force is bigger than the force from a black hole.

And then in particle physics you have to do this mathematical magic trick called renormalization, which somehow gets rid of the infinities. Another reason people don't like the Standard Model.

Wiley
2002-Apr-18, 03:27 PM
On 2002-04-18 09:35, Silas wrote:

On 2002-04-18 08:54, John Kierein wrote:
The big trouble with a point mass with no dimensions, is that if it gets inside something the gravitational force becomes infinite. As R goes to zero the force goes to infinity. If there were such things we'd all be crushed. An infinite force is bigger than the force from a black hole.

Don't the same objections apply to any point-source, such as an electron? At zero distance, the electric field is infinitely dense... The answer is that nothing gets within zero distance...

Exactly. My take on this is that you've reached the limit of the theory's validity. Nature abhors singularities (I mean the mathematical definition here), and any theory that has one is incomplete. Unlike John, I believe black holes exist and they have event horizons; however I do not believe there is an infinitely dense point at the center of the black hole.

John Kierein
2002-Apr-18, 05:10 PM
If nothing gets within zero distance then it must be of finite size - equal to the distance something can get within. So it must not be a point source. If it has mass, it must have dimension.

Silas
2002-Apr-18, 10:43 PM
On 2002-04-18 13:10, John Kierein wrote:
If nothing gets within zero distance then it must be of finite size - equal to the distance something can get within. So it must not be a point source. If it has mass, it must have dimension.

This might be one of those "differences that make no differences..." Since gravitational attraction weakens with the square of the distance, then, if the gravitational mass has a dimension, it might be possible to detect the difference between attraction from the "near side" and the "far side."

Since that difference has never been detected from an electron (yet) we speak of an electron as behaving as if it were a point source of charge, even though that leads to the uncomfortable image of an "infinite" charge density.

(I do not know -- and would enjoy learning -- what the behavior is of an electron and a positron in the final instants of their attraction toward mutual annihilation. Is there a sudden and instantaneous approach toward "infinite" acceleration as the two come within "infinitessimal" separation? Or does the integral of the approach path stay always within a finite range?)

(Might the same not be true of two point masses that come to join into a single point with twice the mass? The acceleration/speed curve only appears infinite, but resolves to a finite value by L'Hospital's rule?)

(I don't know...I'm just asking... I'm actually pleased as punch that I can remember L'Hospital's rule after a couple of beers!)

Silas

Hat Monster
2002-Apr-20, 12:51 AM
If nothing gets within zero distance then it must be of finite size - equal to the distance something can get within. So it must not be a point source. If it has mass, it must have dimension.

It does.
The event horizon.
Inside there, the laws of relativistic physics break down entirely since matter would necessarily be travelling at superluminal velocities if we attempted to apply our physical laws inside the event horizon. You cannot apply physical laws to a place outside of their boundaries no more than Australian laws apply to a Irishman in Dublin.

What do you propose can have the observed mass, the observed gravity, the observed accretion, the observed jets...etc?
Theory must fit fact. Black holes do. No need to throw them out because you have a hard time getting your head around them.

<font size=-1>[ This Message was edited by: Hat Monster on 2002-04-19 20:51 ]</font>

John Kierein
2002-Apr-20, 01:08 AM
If you are trying to say quasars are black holes because of their jets, Try this alternative.
http://www.angelfire.com/az/BIGBANGisWRONG/wheresquasars.html

GrapesOfWrath
2002-Apr-20, 02:05 AM
John, you should update your link on The Big Bang Is Wrong (http://www.angelfire.com/az/BIGBANGisWRONG/) page, for the BABB. Not only does it point to the old board address, it's called "Bad/Bitesized Astronomy Bulletin Board".

Keep up the good work.

John Kierein
2002-Apr-20, 12:15 PM
Fixed it. Thanks. I think some other links may have expired, too. Sorry about that.