Tissa (#55), to emphasise the point implied in my final paragraph, stars in a galaxy do *not* orbit their galaxy as one would predict from Newton’s laws assuming theirs is the only mass in the galaxy. So your argument is based on a false premise, specifically your point 9.

Read the Wikipedia article http://en.wikipedia.org/wiki/Galaxy_rotation_problem

I’m not entirely clear how cosmologists exclude the possibility of enough non-stellar material to account for observed orbits. But this stuff, especially gas and ice and dust, absorbs and reflects radiation. So presumably the amount present can be deduced from spectrographic data and the amount infered by this and other means is insufficient for the job.

In any case, dark mass and energy is apparently needed to make up the total amound of mass-energy which the Standard Model predicts must have been formed in the Big Bang. Ordinary matter falls far short of what is required.

OK, now let’s do one with N in the billions of equal billionth parts of the mass of the combined Earth-Moon system.

> 7) Now we will use some magic, we will make 90% of the N bodies
> invisible, and call them Dark Matter!
> 8).What do you think would happen to the 10% that are still visible?
> 9).You guessed! they will keep moving as before and still obey
> Newtonian Law’s with no velocity discrepancies.

This time let the magic be to make the Earth invisible and call it Dark Matter. Then an alien observer on Mars, say, observing the moon through a telescope for several months would see it perform bizarre cyclic motions superimposed on its orbit of the Sun.

As this motion would not certainly not be Newtonian, they would be able to correctly predict the large invisible mass sufficient to cause the combined centre of mass of that and the Moon to orbit along the approved Newtonian ellipse.

It’s the same with stellar rotation rates - The dark mass is needed to restore Newtonian sanity to observations in conflict with it when only visible mass is taken into account. Somehow you’ve put the cart before the horse.

A Dark Matter thought experiment.

1) Dark Matter was invented to augment the observed motion of
real visible matter, right? right!
2) Dark Matter interacts with real matter via gravitational forces
only, right? right!
3) Dark Matter too interacts with Dark Matter gravitationally
right? right!
4) Therefore Dark Matter must take part in the orbital dynamics
of the system, right? right!
5) The only difference is that Dark Matter cannot be seen, other
wise, it takes part in the gravitational dynamics of the system,
which is purely Newtonian motion, right? right!

Now that we agree, let us do a pure thought experiment.
Let us do an N-Body simulation, where N will be in the billions.

6) All N Bodies will therefore do a Newtonian Samba. Each of the
N Bodies will clearly have rotational motion velocities defined
by Newton’s laws. Therefore only Newton’s Law accounts for
their motions.
7) Now we will use some magic, we will make 90% of the N bodies
invisible, and call them Dark Matter!
8).What do you think would happen to the 10% that are still visible?
9).You guessed! they will keep moving as before and still obey
Newtonian Law’s with no velocity discrepancies.
10)Moral of the story is, Dark Matter don’t matter.
11)There must be another way! I have a hypothesis for another
alternative to Dark Matter at cosmicdarkmatter.com.

/Tissa Perera

I have been to Ned Wright’s tutorial several times over the years, but I find the assumption not only there but also generally (running the film backwards) is that the universe began as an extreme density region. Whatever the inferred history prior to the CMB, all that is “known” is that it is emitted from a hydrogen plasma at 3000 K (correct?). How it got to be that way is what I question. In other words it could be either cooling down or heating up. There seems to be no consideration of a heating up scenario. I think this is for reasons of the historical growth of physics, e.g. bodies of matter, conservation of mass-energy.

Re the balloon analogy, I dimly understand the mathematicians have a special sense of 2D and 3D, sphere and ball. It is difficult to ignore the interior of the ball, I wonder how the mathematicians do it. But the key to my idea is in your sentence, “The space will just keep expanding, and of course there is no “rubber” that will break.” If the initial condition is spatial expansion, the universal expansion rate will be dictated at the moment of expansion. The “spatial field” will expand at its full potential, which it cannot alter without breaking its own natural law (or our understanding of the constancy of natural laws in our frame). The initial condition therefore dictates a constant expansion rate and immediately invokes space and time measurement, including added volume per unit of existing volume of the ball.

The thing is that, after a very short time, for every added unit of constant radial expansion the added volume is less than the natural law (initial condition) requires. That is, each unit of existing volume adds less and less new volume as the ball expands at its limit. In other words, if every ‘point’ within the expanding field replicates the initial condition of the field itself, there is not enough space within the field to absorb the expansion potential – even while the field is expanding at its full potential at its ‘edge’. So although there is no rubber that will break, the initial condition of constant expansion rate produces pressure inside the ball. I am told that rotation is a degree of freedom. So rotation absorbs the pressure. I think it would have to be rotation on the equivalent of three axes in order to absorb pressure from all directions. It also has the effect that space in the rotating region does not expand. If you go by Planck times and Planck lengths and rotation rate of c applied to ~10^23 hertz frequency for protons and ~10^20 hertz frequency for electrons, I calculated something like 10^64 particles would be created in one second. Each non-expanding region forms effectively a zero point for the spatial field, so the working of the natural law restarts from an effective zero radius with each matter particle created. Then the cycle repeats itself, constantly creating new matter just inside the edge of the ball, but I think with larger intervals, so you end up with dense regions of matter and voids. Large enough voids may create pressure and rotation, i.e. dark matter.

but there is no conservation principle for energy in cosmology!

The expansion of the universe is likened to a baloon blowing up, but of course in three dimensions instead of two. However, ignore the idea that this sphere encloses a higher dimensional region or a ball. The space will just keep expanding, and of course there is no “rubber” that will break. I think Sean posted the Ned Wright’s cosmology website. There is a lot of good stuff there which can help anyone understand some of this stuff.

Lawrence B. Crowell

I am of two minds about whether to continue. In view of your last post just read, I don’t expect an answer but I will give this one last try. What I already wrote was:

Thank you for your concern, but I cheer up by laughing at myself!
I notice the term Lambda above. I wonder what your interpretation of Lambda is. More broadly, I wonder about gravitational instability and the feature of a limited amount of mass-energy in the universe. NASA says the universe is supposed to have “released” all its mass-energy within a certain time, which requires a kind of mass-energy “bank” – once all the mass-energy is withdrawn from the bank, there is no more. Yet at the same time there is an entity whose influence increases (dark energy).

However, what if the universe is not the inflation-powered surface of a balloon, but the volume inside the balloon, expanding at a constant rate powered by a positive energy density, creating positive pressure, in turn creating matter which absorbs the local pressure resulting in local non-expansion (perceived as gravitational attraction/spacetime curvature), followed by further expansion (perhaps perceived as accelerated expansion depending on frame), pressure inside the surface, and further matter creation, in cycles? No need for rho crit., Lambda, etc. since the system stabilizes itself by cyclical matter creation.

When you quit laughing, how about a round of “Row, row, row your boat. . . .”?

Lawrence B. Crowell

Yes, I second that. He does a cracking good job here, much appreciated, and doubtless in other forums besides. What’s more he’s written several books on physics, as a quick search on Amazon reveals.

We still have this dark energy pushing everything apart and all that stuff falling into black holes?
What led me through the mirror and down the rabbit hole in the first place was that Omega has to be very close to one. If gravitational contraction and universal expansion are in general equilibrium, it still seems like half a cycle. Something is pushing space apart, but something else is pulling it together at an equal rate.

I know I’m thick, but what am I’m missing?

First of all, thank you. You are welcome to add arxiv ID and refs on your relevant publications, however I am interesting neither the universe distant future nor the universe distant past.

Regards, Dany.

What you need to do is to understand the meaning of a co-moving frame in relativity theory.

The percentage of so called dark energy will increase and asymptotically approach 100%. The spacetime will also asymptotically approach a pure deSitter spacetime. This is of course unless there is not some unexpected physics or cosmological principle which might “kick in” in the future. The Hawking-Gibbon effect also indicates that the cosmological event horizon at a radius

or the reciprocal of the square root of the cosmological constant, will receed away as it emits a Hawking type of radiation similar to black hole radiance. This means that over a supendous time period the universe will approach being a spacetime that is a Minkowski spacetime. This is a perfect void, or the final “heat death,” or the attractor point in the phase space of solutions to the Einstein field equations.

It might seem to be a dismal end, and it does point to a future universe that will ever more slowly wind down. Yet we are in a sort of “sweet spot” in the whole spacetime, where we can observe the universe’s distant past, but are not too close. In another few 10’s of billions of years things will be too redshifted for observers to measure the CMB or to seem much beyond their local galactic neighborhood. But I’d suggest not becoming like Woody Allen in “Annie Hall” where he worries about the universe breaking up. It is maybe better to sing or whistle the Monty Python song, “Look on the Bright Side of Life,” from their movie “Life of Brian.”

Lawrence B. Crowell

Give me ref., please.

Regards, Dany.

I should also say that there are parts here which is where I am working. The quantum critical point is where the mass of the quasi-particles, or in the case of Landau fluids in solids the quasi-electron, diverge. There have been experimental demonstrations that there is a critical point and there is close to there a divergence. Yet near the quantum critical point there is appearance of new states of matter, and indications this is connected to high Tc. A divergence of this sort always points to some sort of new physics lurking beyond the “horizon.”

Lawrence B. Crowell

Lawrence B. Crowell:” This time turns out to be related to temperature by t=h/kT…As the temperature heats up it also means that the fluctuation is stronger or its coupling is made larger and a phase transition will ensue… This correspondence and the phase transition is a quantum critical point.”

Give me ref., please.

Regards, Dany.

H. von Lohneisen, A Rosch, M. Vojta, Rev. Mod. Phys., 79, 1025 (2007)

S. Sachdev, Quantum Phase Transitions, Cambridge U. Press (1999)

An interesting point to consider on whether space is expanding, or objects are moving apart in stable space is that the speed of light is presumed to be stable, such that if the universe were to double in size, two objects x lightyears apart would become 2x lightyears apart. So space as measured by C doesn’t expand, rather the distance in lightyears is increased.

This does pose a problem for an expanding universe hypothesis, since the geometry of redshift would mean that we are at the center of the universe. That’s why the original expanding universe theory was amended to say that space itself is expanding, not just that the objects in space are flying away from each other.

If space has a negative curvature in between gravitational wells, effectively opposite the positive curvature of these wells, the potential effect might be the redshift that is observed. (As if the light had to run up the down escalator.) So that space does expand between gravity wells, but it also collapses into these wells, neutralizing the overall effect. Since the overall universe isn’t expanding, this expansion of space would result in pressure on these gravity wells, as you mentioned. I’ll leave it at that, since I’ve bored many of the people here with it already.

So there is the Lorentzian time and there is this Euclidean time and there is a Wick rotational map between the two. So distinct fluctuation in the Euclidean case which have moduli that are Hausdorff, separable and “nice” correspond to a set of moduli in the Lorentzian case which are not.

I would think that it would be meaningless to consider a point in time, if time is a measure of motion, like temperature, since there would be no motion at a point. Sort of like the Uncertainty Principle; Can’t have both position and momentum. A point would be cessation of time, like absolute zero is a cessation of temperature. So would this cause problems with measuring units of time as between two points? Is this what you are getting at in the above quote? That the “nice,” distinct Euclidian time breaks down in Lorentzian time, where it is actually being ‘produced’ by the motion of the clock.

Give me ref., please.

Regards, Dany.

John Merryman on Mar 8th, 2008 at 6:54 pm
Lawrence,

Temperature is a very interesting concept, encompassing the full spectrum of activity, from absolute zero to the speed of light. It would seem, in some respects, that time is a component of temperature, just as three dimensions are a model of spatial volume, not the basis for it.

————-

In quantum field theory it is a common practice to Euclideanize time by letting time go to t —> it. This time turns out to be related to temperature by

This time is not exactly the same as the Lorentzian time, what we measure on a clock (or might we say what a clock “produces”), but is really a measure of the time where quantum fluctuations may be observed. Sometimes the term quantum fluctuations causes trouble, so it really is more the distance in a Euclidean 4-dim space where an instanton (a tunnelling state etc) with a certain magnitude can appear. As this temperature becomes very small the fluctuation time becomes large and the strength of the fluctuation, if we qualitatively invoke the Heisenberg uncertainty principle

and consider this instanton time t as this uncertainty in time. As the temperature heats up it also means that the fluctuation is stronger or its coupling is made larger and a phase transition will ensue.

This gets into some fascinating stuff! The Lorentzian time implies that the moduli space is not separable. Two moduli, points in the space of “gauge equivalent connections,” are not separable in a Hausdorff point-set topological definition. The topology is Zariski. I can go write more about this if needed, but this gets us into some rather serious stuff. So there is the Lorentzian time and there is this Euclidean time and there is a Wick rotational map between the two. So distinct fluctuation in the Euclidean case which have moduli that are Hausdorff, separable and “nice” correspond to a set of moduli in the Lorentzian case which are not. Physically this means there is some scale invariant physics (again to go into would require a bit of writing work) of phase transitions associated with the correspondence between fluctuations at various pseudo-time scales (or temperatures) and their Lorentzian versions.

This correspondence and the phase transition is a quantum critical point, which have been observed with High temp superconductors and in the physics of Landau electron fluids in metallic crystals in the actinide plus transition range. This also shares some aspects of physics with the Hagedorn temperature of strings.

Lawrence B. Crowell