Friday, February 23, 2007

The Slayer and Ever-Changing Moods

Among the audience at Sunday's talk on "Dark Energy and Multiverses" were Jennifer Ouelette and Sean Carroll. With Lawrence Krauss giving the introductory talk, we had the authors of "Physics of Star Trek" and "Physics of the Buffyverse" in the same crowded room! Jennifer was able to stay an extra day and autograph some books.

Buffy was once a seemingly ordinary girl. She didn't choose to be the Slayer--the responsibility was thrust upon her. I hope you will excuse Buffy for occasionally being combative or showing attitude. Slayers have to defend ourselves.

Another fascinating book picked up at AAAS was "Brave New Universe" by Paul Halpern and Paul Wesson. This is an entertaining book suitable for the general reader. One chapter is entitled: "Ever-Changing Moods: Did Nature's Constants Evolve?" How the world has changed!

"If signals once traveled from one part of the universe to another faster than they do now, that could explain why space is so uniform. Through a rapid and far-reaching process of thermal equilibrium, temperatures in the early universe would have had ample opportunity to even out. Also, any significant pockets of high or low-density matter would tend to even out over time through either the release or accumulation of energy. Although such processes would violate standard conservation laws, they would be permitted of the speed of light could vary. This levelling out would lead automatically to a flat cosmos. Hence, the horizon and flatness issues would vanish, with no inflationary smoothing needed to accomplish these feats.

"Furthermore, alterations in the speed of light would affect astronomers' measurements of the velocities of distant galaxies. The supernova results of Schmidt's and Perlmutter's groups, among other measurements, would require re-interpretation. Consequently, the universe might not be accelerating after all."

The odds are a thousand to one against, but we are winning!

12 Comments:

Blogger QUASAR9 said...

Dark matter is one of the greatest mysteries in modern astronomy. Scientists use the term as an umbrella definition for all the invisible "heavy stuff" in the universe. Astronomers currently believe that there are two components to dark matter. One part of dark matter is made up of exotic materials, different from the ordinary particles that make up the familiar world around us. The other part consists of dark celestial bodies - like planets, black holes, or failed stars - which do not produce light or are too faint to detect from Earth.

Everything in the universe moves. In our own Milky Way galaxy, our Earth moves around the Sun, and the Sun moves around the galaxy's center. By measuring how fast stars at the edge of the galaxy move, astronomers can calculate the Milky Way's weight. The faster the outer stars move, the heavier the galaxy is.

Spitzer Seeks Out Milky Way Dark Matter

Louise, the speed of light enables us to determine how 'distant' the outer stars are, supposing they are closer and therefore moving slower that could and would make the galaxy less heavy. But it would not make dark matter go away altogether.
You yourself are an advocate for the existence of black holes, and it is not unreasonable to suspect that there may well be exotic particles and more yet to be 'detected'

Stars and Galaxies, some of them rotating in different directions (and some of them dark) and their changing mass, would enable the 'visible' universe to expand.

PS - Conservation of energy states that the total amount of energy in an isolated system remains constant.
The law of conservation of energy states that energy can not be created (made from nothing), or destroyed (made to disappear to no-where) and that energy can be changed from one form to another.


Some constants we rely on to make calculations, you want to alter c
but you could equally alter total E

Who says the 'visible' cosmos is an isolated system, and is not itself just a bubble in a larger sea, incidentally in a sea so vast we would have no idea of knowing where or when to start assuming when equilibrium might be reached

Who says there are no forms of energy we have not yet revealed or measured

12:27 AM  
Blogger nige said...

This comment has been removed by the author.

5:41 AM  
Blogger nige said...

Quasar9,

You might add: "Who says there are no UFOs?"

I'd like to see evidence, which is not an ad hoc model involving dark energy. Ptolemy's epicycles were an ad hoc model of the known cosmos in 150 AD.

You can't claim that the evidence on which the model is based is evidence for the model. The model has to correctly predict something interesting (i.e., a far out extrapolation from existing data might do, but just a prediction which is an interpolation between known data points won't usually be impressive) which didn't go into the data it was originally constructed upon, to be taken seriously.

For example, Kepler's laws were only a better model than Ptolemy's and Copernicus' epicycles because they were much simpler (both Ptolemy and Copernicus used epicycles to model the known cosmos; Ptolemy has 40 for the Earth-centred universe, and Copernicus has 80 for the solar system with false circular orbits).

What really established Kepler's laws scientifically as fact was when they were explained by an inverse square law of gravity, which worked for the moon just as for apples falling on the earth.

An apple falls with an acceleration of 32 ft/s/s at earth's radius. Hooke's and Newton's inverse-square law predicts that at the moon's distance from us, 60 earth radii, gravity is 32/(60^2) = 0.0089 ft/s/s.

Newton validated this figure by showing it is the same (within experimental error at that time) as the centripetal acceleration due to the Moon's orbit of the earth, a = (v^2)/r, where v is moon's orbital velocity (i.e., circumference of orbit divided by period of orbit) and r is the average distance to the Moon from the middle of the earth.

This is the sort of thing a scientific theory must do. Dark energy is pseudoscience by comparison, lacking theory, lacking objective evidence, relying on the assertions of groupthink and mainstream ideology, hyped by obsequious people in the media and and stringers who don't understand why experiments are required to validate theories before they gain widespread attention.

5:47 AM  
Blogger L. Riofrio said...

Nice to hear from both of you. Q9, I think wew should read about the difference between dark matter and dark energy. Many observations show that there is some kind of dark matter out there, which could be Black zholes or possibly some kind of exotic particle. "Dark energy" is another story entirely, an entirely hypothetical repulsive force.

8:55 AM  
Blogger QUASAR9 said...

Hi Nige, I have no particular axe to grind, and no possible theory I prefer over another.
I am simply stating that if we can change one assumed constant we can change and & all assumed constants.

If you read my last statement you may see what I am getting at:
"Who says the 'visible' cosmos is an isolated system, and is not itself just a bubble in a larger sea, incidentally in a sea so vast we would have no idea of knowing where or when to start assuming when equilibrium might be reached"
- Quasar9


Not that I advocate pocket universes as expounded by L Susskind or island universes by A Vilenkin per se but that the 'visible' universe may only be a portion (or bubble) of the whole, the Megaverse or Greater Universe.
That there is more than one type (or state) of blackhole, some may evaporate, whilst others like Lee Smolin's 'blackholes' may turn out to be wormholes (or corridors) to other parts of the universe.

9:03 AM  
Blogger Kea said...

Funny! I'm glad you have fun at these gigs. So far my colleague David Wiltshire hasn't had much response about his own NO-DE model. I think the problem is that he presents so much evidence that people couldn't be bothered wading through it.

10:11 AM  
Blogger nige said...

Kea, it certainly fits the data curves well: http://cosmo05.uni-bonn.de/up/wiltshire.pdf.

I don't understand what the physical basis is for the assumptions about the nature of the universe and its metric, see page 6:

"Assume like Kolb, Matarrese, Notari and Riotto that (1): we live in an underdense bubble, S, in a spatially flat universe with bulk metric ..."

The metric given contains a complex scale factor multiplying all of the spatial (but not time) differential elements.

Page 5 states: "Kolb, Matarrese, Notari and Riotto hep-th/0503117 claim Primordial inflation explains why the universe is accelerating today with no dark energy..."

So the basic metric assumed seems to have acceleration due to inflation, which offsets the gravitational deceleration effect to give the observed supernovae recession data. The way dark energy is being discredited is by showing that the inflationary model explains the data without requiring dark energy.

So I think it is a nice model, cutting out dark energy and replacing it by an inflation effect. Since some kind of inflation is required in mainstream (fixed gravitation constant G) cosmology, it is an economy to cut out dark energy and have the effect due to inflation instead.

Physically, it seems far better than the mainstream lambda-CDM cosmology. People probably aren't wading through it simply because it is not mainstream.

(Unfortunately, I don't understand the physical basis of that cosmological model and I "claim" to have a gravity mechanism which is a bit simpler and which gets rid of both dark energy and inflation. The dark energy disappears owing to gravity causing exchange radiation being redshifted - reduced in effective energy and coupling constant strength - when exchanged between rapidly receding masses, such as the universe around us and a distant supernova. The evidence for inflation is the small size of ripples in the cosmic background radiation which originates from 300,000 years after the big bang. The gravity mechanism implies that the universal gravitational constant, G, is proportional to the age of the universe, so it was smaller at 300,000 years after the big bang, causing smaller sized ripples as observed! Of course, Teller allegedly disproved varying G in 1948 by showing that if it did vary by itself then the sun's fusion rate would vary with dramatic effects for evolution on earth, but this assumption of Teller's is wrong because the mechanism - and Lunsford's unification of electromagnetism and gravity which seems to be consistent with it - suggests that there is a link of gravitation to electromagnetic force, whereby fundamental forces vary with time in the same way, so increases gravitational compression in the sun is accompanied by increased Coulomb repulsion between protons, so there is no net effect on the fusion rate which depends on the protons approaching close enough for the strong force to fuse them.)

12:43 PM  
Blogger Kea said...

Nigel, his new paper is quite a lot clearer.

12:48 PM  
Blogger nige said...

http://arxiv.org/PS_cache/gr-qc/pdf/0702/0702082.pdf is the paper. Abstract states:

"... Matter is modelled as an inhomogeneous distribution of clusters of galaxies in bubble walls surrounding voids, as we observe. Gravitational energy differences between observers in bound systems, such as galaxies, and volume–averaged comoving locations in freely expanding space can be so large that the time dilation between the two significantly affects the parameters of any effective homogeneous isotropic model one fits to the universe. A new approach to cosmological averaging is presented ... The angular scale of the first Doppler peak in the CMB anisotropy spectrum fits the new model despite an average negative spatial curvature at late epochs, resolving the anomaly associated with ellipticity in the CMB anisotropies. Non–baryonic dark matter to baryonic matter ratios of about 3:1 are typically favoured by observational tests. A number of other testable consequences are discussed, with the potential to profoundly change the whole of theoretical and observational cosmology."

It is impressive that it first Doppler peak in the CMB anisotropy spectrum, and it is valuable that this paper gives so much comparison between prediction and measured data. It would be very interesting to compare all the available models and see how they all fare in terms of explaining as much as possible, with as few "epicycles" (like dark energy) as possible.

1:11 PM  
Blogger nige said...

Sorry my typing missed out a couple of words, the last comment should read in part as follows:

It is impressive that it fits the first Doppler peak in the CMB anisotropy spectrum,

1:17 PM  
Blogger CarlBrannen said...

One of my life objectives is to somdeay watch a Buffy the Vampire Slayer rerun.

2:31 PM  
Blogger L. Riofrio said...

Kea, you can tell David that even in this day and age it takes time for an idea to get out there. One would practically have to attend a conference every week, which isn't such a bad idea!

3:51 PM  

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