Orion38: "I am very surprised because I always thinking than the aspect wave/particles could only apply to the light (photons) and not for all the electromagnetic spectrum. This is very interesting."

All wave packets in the electromagnetic spectrum are photons--that's what I'm saying. Commonly we refer to photons as 'light' but as I understand it everything from AM radio waves to gamma rays are also streams of photons. Our common usage in this case leads us a bit astray. Don't take my word for it, though; here's a quote from one of NASA's educational web pages:

-----------

"Electromagnetic radiation can be described in terms of a stream of photons, which are massless particles each traveling in a wave-like pattern and moving at the speed of light. Each photon contains a certain amount (or bundle) of energy, and all electromagnetic radiation consists of these photons. The only difference between the various types of electromagnetic radiation is the amount of energy found in the photons. Radio waves have photons with low energies, microwaves have a little more energy than radio waves, infrared has still more, then visible, ultraviolet, X-rays, and...the most energetic of all...gamma-rays."

----------

But on the wave-particle front, even electrons (and other particles) can be made to show a wave nature as well as a particle nature. In fact, many explanations of electron tunneling--say, in a tunneling diode--refer to one wave-like behavior of electrons. It's pretty cool! And electron orbits in an atom are also related to wave-like behavior of the electron. Here's a link to a page explaining both tunneling and electron orbitals as wave-like behaviors: University of Oregon lecture notes.

<font size=-1>[ This Message was edited by: DStahl on 2003-02-27 03:09 ]</font>

a mobius strip universe would be one sided.

I don't know of any direct estimations for effects of Whitehead's gravitational anisotropy on distance measurements. Still, there's an old work by Will (Will, C.M. Relativistic gravity in the solar system. II. anisotropy in the Newtonian gravitational constant. Astrophysical J. 169, 141-155 (1971).) where he estimated the G anisotropy induced by our galaxy in the Solar system as 0.00002%. IIRC, the amplitude of Whiteheadian anisotropy from compact remote masses goes as M/R. That implies maximum anisotropy should come from the local supercluster rather than the galaxy, since above that scale the non-uniformity of density (deltaM/M) goes down rather exponentially. The M/R ratios as seen from Earth for Milky Way and the local supercluster differ by a factor of ~ 1000, so the Will's calculated Whiteheadian anisotropy could be (very roughly) modified by that factor to about 0.02%. The value order seems pretty close to reported experimental data.

It's not quite clear to me as to how those figures might be related to existing distance measurements. Any ideas?

I think, Agora, you should update your estimations on the error on G.

In fact, it's not my/your little selves that matter here. There's a relatively huge error margin in the official CODATA G value, and that used to be smaller not so long ago. We (me/you/anybody interested) should ask why it happens so.

As to me personally, I'm quite up to date with the open info on relevant developments, thank you.

My definition of the universe includes our spacetime and any possible others if they exit. When astronomers and physicists theorize about an expanding universe, are they talking about our spacetime, all spacetimes or just space?

Well, most observationalists are talking about our "global" spacetime defined by our past and future lightcones. The stuff we know occurs. Theorists tend to be a bit broader and laugh at the petty existentialism that the observationalist embraces. Just because there is a space-like rather than time-like separation for the theorist doesn't mean the event is outside of our universe. So they tend to include everything that "exists" as part of the universe, for the most part.

cyreks reply:

Cosmogony is just a fancy word for 'creationism'.
It is of Greek origin that is derived from the Book of Genesis.

The trouble with GR is that Einstein himself admitted that he made a big mistake by introducing his cosmological constant to counteract the effects of gravity.

Ever wonder why he did this?

I have thought about this and I believe he did this because he realized that if space can cause matter to curve, than it can erode its momentum.
Therefore his universe would collapse.
That, to me, is why he introduced the CC.

The BB supposedly saved his universe but to me, the BB is cosmogony, not cosmology.

Cosmogony is just a fancy word for the 'creation theory'.

This still doesn't make sense in my mind...

Because if you have empty space, there is nothing to measure, so it is meaningless to say that space expands.

I guess it is just a mathematical concept.

Here are some more contradictionary issues involving "space expansion".
If the "expansion of space" causes light to become redder, why doesn't it affect atoms and other material objects to become larger?

Einstein believed in a static universe. His GR equations indicated that the universe was expanding. But, since it couldn't be expanding, he decided there must be some sort of "anti-gravity" force at work. He inserted this into his equations as the cosmological constant.

When proof was found that the universe was indeed expanding, he stated that the cosmological constant was his "biggest blunder."

Cosmogony is a "theory for the origin of the universe." Cosmology includes "the origin, structure, and space-time relationships of the universe."

BB theory is cosmology.

__________________
Never attribute to malice what can be adequately explained by ignorance or stupidity.
Isaac Asimov

Well, thanks for the reply, but there is a specific scientific defintion for the word already provided by ljbrs.

No, it wasn't a mistake... it was just unneccessary. The reason Einstein referred to it as his "biggest blunder" is that the natural solution to GR is a dynamical universe. He could have predicted the expansion before Hubble observed it.

Well, I just told you why.

1) Space doesn't cause matter to curve. Matter doesn't even cause space to curve. Matter can cause spacetime to curve.

2) Space has no momentum. Matter can have momentum. Matter that is accelerated by gravity has MORE momentum, not less.

Well, therefore is wrong because you had priors that were absurd. But the point of the matter is that the universe would be DYNAMICAL... and collapsing gives the matter in the universe MORE momentum, not less.

Again, you're just throwing terms around without giving any basis in observational fact. Right now you are sticking your head in the sand refusing to see the observational evidence that we have been patiently spoon-feeding you, only to have it spit back at us with a nonsensical platitude. That's just immature.

The Big Bang has observational evidence behind it and is well described by mathematical theory that is robustly consistent. Those are the things you have to attack if you think that the Big Bang is wrong. Just saying it's a "creation theory" and therefore is wrong doesn't cut the cheese.

Nothing, however, is something. A vacuum is not unmeasurable. In particular I can place things in it. That's what we measure.

It is actually meaningless for you to say it is meaningless. We can define a difference in position between objects, and that difference represents SPACE in between them.

Let's put it bluntly, in an empty universe we can STILL solve for the behavior of Einstein's Equations. Such a universe is called a Milne Universe. Look it up.

Now you're getting it.

Because atoms and other material don't move at the speed of light.

cyreks reply:
In the comments above, Dr. Don and JS say that 'space is expanding the light waves'.

This then tells me that light and space are intertwined and light is using space as a means of transmission?

I aleays thought that photons use the EMF fields as their means of transmission.
EMFF's extend to infinity and permeate space. The photons use these fields to move through space rather than using space as its means of transmission.


About 'cosmogony', this is a fancy word for the creation theory because it is derived from the Greek and subsequently, from the Book of Genesis.

<font size=-1>[ This Message was edited by: michael cyrek on 2003-03-16 12:35 ]</font>

In a manner of speaking, that's exactly right. Light is a means of converting between one set of dimensions (space) and the other dimension (time). Specifically, on the local scale, the speed of light is the fastest thing there is.

Remember that EMF is strictly voltage, but E&M fields are different. Your nomenclature is a bit off. EMF stands for Electromotive force, not for Electromagnetic fields.

However, it is a direct consequence that the vacuum solution for electromagnetic waves travels with gauge invariance at the speed of light that we have this rule in special relativity that the speed of light is the fastest thing there is. It may seem counterintuitive, but that's the result.

I am almost certain you are wrong on this point, but feel free to provide a citation to back yourself up. I'm almost certain that "cosmogony" was not derived from the Septugiant.

The last time I looked at this, I think that ratio was closer to 1 than 1000. What figures are you using?

<font size=-1>[Fixed formatting]</font>

<font size=-1>[ This Message was edited by: kilopi on 2003-03-16 20:06 ]</font>

Milky Way is about 10^9 solar masses and 25 kpc diameter, local supercluster is about 10^15 solar masses and 50 Mpc diameter. How did you get at the ratio of 1?

I may have used a higher mass and lower diameter for the Milky Way, although I don't have the figures handy. Where'd you get yours? This site says 2x10^11 solar masses, and about 20kpc to the center which makes the ratio close; this site says 4x10^11 solar masses, which would make the ratio even closer.

10^11 solar masses sounds about right to me.