Dark thoughts

.. and another thing!

2010-09-01T08:27:00.002Z

How can there be any such entity as a fundamental particle when any particle can be smashed into smaller particles given sufficient energy?

What would be the implications for gravity and the standard theory if mass were a manifestation of a distortion of space-time?

How do gravitons escape from a black hole?

How significant is the correction for the finite speed of gravitons when establishing the existence of dark matter?

Out of the corner of our eyes...

2007-02-06T20:13:00.000Z

So we have more compelling evidence that it's there and we're beginning to unravel its shape!

In the February issue of Physics World, Douglas Clowe and Dennis Zaritsky discuss how studies announced in August last year of one of these cluster mergers, nicknamed the "Bullet Cluster", have given astrophysicists some of the best evidence yet for the existence of dark matter.

Work to produce the first ever 3D map showing the distribution of dark matter in the universe has been reported in New Scientist, 13 January 2007. The map was created by combining measurements of intervening matter by gravitational lensing of light from distant galaxies with data on distance derived from red shift measurements of the galaxies

Now the worry is that there are regions where there is dark matter but no visible matter and vice versa.

What if dark matter were not quite in our dimensions? What if it were to occupy a space very adjacent to our own and were to develop with a subtly different set of 'fundamental' constants. It would neither mirror nor shadow visible matter yet it would influence the matter in our niche in the Universe; and of course vice versa.

Paradigm shift

2006-12-25T21:42:00.000Z

Paul Davies in The Goldilocks Enigma asks 'Why is the universe just right for life?' This question simply reinforces a self-fulfilling prophecy in which we will forever wonder at the unlikely combination of circumstances that leads to our existence.

This paradigm is unproductive.

I ask 'What is the form of the universe in which the niche for human life exists?' We know a great deal about that niche. But what do we know about the universe that cradles it?

I believe that this is a more productive paradigm. I shall show that it leads, amongst many other things, to a description of a universe in which dark matter is a manifestation of the universe just beyond the niche that we occupy and observe.

Nooks and crannies in the omniverse

2006-10-21T14:31:00.001Z

After Fig. 4.2 of John D Barrow's The Constants of Nature

NM: Newton's mechanics (G=h=1/c=0)
NG: Newton's theory of gravity (h=1/c=0; G≠0)
SR: Einstein's special relativity theory (h=G=0; 1/c≠0)
QM: Quantum mechanics (G=1/c=0; h≠0)
GR: Einstein's general theory of relativity (h=0; G≠0; 1/c≠0)
QFT: Relativistic quantum mechanics (G=0; h≠0; 1/c≠0)
NQG: Newtonian quantum gravity (1/c=0; G≠0; h≠0)
TOE: Relativistic quantum gravity (G≠0; h≠0; 1/c≠0)

George Gamow (Mr Tompkins in Paperback) asked questions about some of these constants. What would our universe be like if the speed of light were 186 miles per hour rather than 186,000 miles per second? What if Planck's constant were very large? His purpose was to teach an understanding of special relativity and quantum mechanics.

My purpose is to explore the consequences for our universe sitting alongside other universes with different speeds of light, different values for Planck's constant, and so on as part of an n-dimensional omniverse.

[I'm not sure that I have used the correct terminology here, so I'll try to define exactly what I mean by the term 'omniverse'. Our existence is in a universe defined by three spatial dimensions, time and a number (Ω) of 'constants'. Other universes may exist with different values of the Ω 'constants'. My definition of an omniverse is the co-existence of all these universes in a (4+Ω)-dimensional entity.]

So, what keeps our universe 'on the rails' laid down by its values of C, G and h? And is there an influence of our universe on those adjacent; or vice versa?

But above all else, is there any reason to believe that we live in a 'special' universe rather than in a nook or cranny of the omniverse that has properties favorable to our existence? If we inhabit this niche, then anthropic principles (e.g. see Barrow & Tipler The Anthropic Cosmological Principle) become an irrelevance!

Food for lazy brains

2006-10-21T13:34:00.001Z

George Gamow has published some really stimulating books on modern physics. They were available while I was at college in the early 1960s. If I had read them, physics would have been far more exciting and I would have been so much more enthusiastic about my studies:

Mr Tompkins in Paperback (Canto) comprises Mr Tomkins in Wonderland and Mr Tomkins Explores the Atom and gives fascinating insights into special relativity and quantum mechanics respectively in worlds where the speed of light is made small and Planck's constant large.
Gravity from Newton to Einstein and beyond.
One, Two, Three...Infinity: Facts and Speculations of Science
The Creation of the Universe

But I didn't read them and was bored with physics and .....

I discovered Gamow's books this summer when I read The Constants of Nature by John D Barrow - and I only read that because I had enjoyed Barrow's collaboration with Frank J Tipler on The Anthropic Cosmological Principle (Oxford Paperbacks)

The good news is that I am now well and truly hooked by Roger Penrose's The Road to Reality: A Complete Guide to the Laws of the Universe and Brian Greene's The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory. Let's hope that I haven't left it too late!

Elegant, beautiful and PROVEN

2006-09-12T07:14:00.000Z

I now have my outline understanding of a new physics, an ability to explain the whole of existence in an elegant and beautiful way. So how do I prove it?

In earlier posts I have objected strongly to the building of new theories, each of which is postulated to remove the problems created by the old one, ever more speculative but ever less proven. I have decided to look for proof not in the furthest reaches of the Universe; nor the beginnings of existence; nor the small anomalies in the trajectories of Pioneer space probes.

I believe that any new theory of everything must offer an insight into at least one of the many unexplained phenomena that currently litter the boundaries between science and nonscience. I suspect that phenomena such as ball lightning and dowsing offer the best chances of a breakthrough. Telepathy, ghosts, UFOs ... may not be irrelevant but they are not top of my list. The evidence is inconsistent and I don't wish to be labelled as a crank!

Darkness was upon the face of the deep

2006-04-15T17:53:00.000Z

In the very beginning was the void. Nothing existed; neither mass nor energy, linear nor angular momentum, electrical charge nor electromagnetic field. And then a fluctuation in the void created dimensions; time and space propagating into our universe.

Our Universe is characterised by time that is homogeneous so that energy is conserved.
And the space in which we live is homogeneous so that momentum is conserved and also isotropic so that angular momentum is conserved.

If these characteristics have been unchanged throughout the history of the Universe then our existence has neither energy, nor momentum, nor angular momentum.

The behaviour of our Universe is ruled by fundamental constants that have values finely balanced to enable our existence. These balances are perceived to be so unlikely that innumerable anthropic principles have been proposed to explain our precarious existence. Yet we do not wonder at the existence of a fragile flower clinging to life on a mountain rockface. Nor are we particularly surprised when worms are observed living in temperatures of 50C around deep-sea vents at the bottom of the Pacific.

Yet how constant are these 'fundamental constants'? Evidence is emerging that at least some of them are not quite so constant. The proton-electron mass ratio may have decreased by 0.002% in the past 12 billion years. And some claim that the fine structure constant is changing.

What if the hidden dimensions that are postulated to describe our Universe are not 'curled up'? What if fundamental constants define a region in the seven hidden dimensions where our Universe exists? No anthropic principle need be invoked because our Universe is simply a localised four-dimensional existence in an eleven-dimensional 'Omniverse'. If fundamental constants were shown to be not constant then this would be an indication that our Universe is moving around in the seven hidden dimensions.

Such thoughts raise the intriguing prospect that other universes capable of supporting life forms might exist elsewhere in the Omniverse. They are unlikely to bear even the remotest resemblance to our Universe but there might be circumstances in which their influence could propogate through the Omniverse to affect our existence.

Accelerating Universe

2006-02-06T12:25:00.001Z

Observations show that almost everything in the universe is moving away from us and that the further away something is the faster it is moving away. Hubble demonstrated that the redshift of light from galaxies was linearly correlated with their distance with a constant of proportionality now known as Hubble's constant. However, during the late 1990s, observations of type Ia supernovae suggested that the expansion of the universe is accelerating.

So not only is dark matter invoked to explain the dynamics of galaxies but now dark energy is invoked to explain the accelerating expansion of the Universe by opposing the force of gravity! These dark materials overwhelm the directly observable substance of the cosmos:

MOdified Newtonian Dynamics (MOND)

2004-12-15T20:37:00.000Z

Mordehai Milgrom (see Scientific American Aug. 2002) postulates a modification to Newtonian dynamics which reveals itself when accelerations are smaller than a given value that is proposed as a new constant of nature.

This modification is claimed to explain most features of galactic dynamics without recourse to dark matter, including the Tully-Fisher correlation between galaxy brightness and the orbital speeds of stars in the outskirts of spiral galaxies.

MACHOs & WIMPs

2004-12-10T08:37:00.000Z

Hot dark matter moves at relativistic speeds. One candidate is the neutrino which is now known to have a small mass but insufficient to account for a significant amount of the missing mass.
MAssive Compact Halo Objects (MACHOs) and Weakly Interacting Massive Particles (WIMPs) are candidates for cold dark matter.
MACHOs include brown dwarfs, cooled white dwarfs, neutron stars, black holes and minor bodies such as planets, asteroids and comets. Measurements suggest that such material can account for no more than 20% of the Milky Way's dark matter halo. WIMPs have yet to be detected.
The search for dark matter continues but what of other possibilities? Is it correct to assume that stars in a galaxy, and galaxies in a cluster, are gravitationally bound? How would we know if they were not?

Gravitational lensing

2004-12-10T08:29:00.000Z

Measurements of gravitational lensing confirm the values for masses derived from galaxy dynamics.

Mass-to-light ratios

2004-12-09T17:28:00.000Z

The two types of mass measurement for galaxies give very different answers. Those based on the effects of gravity (dynamics of stars determined from measurements of redshift) are ten times greater than those inferred from brightness. The mass-to-light ratio for the Sun is 1; the mass-to-light ratio for galaxies is ~10. The mass-to-light ratio increases to ~100 when galactic halos are included; and rises to ~300 for clusters of galaxies.

Standard reasoning asserts that, since bright matter underestimates the amount of mass in a galaxy, this 'missing mass' must be present in a 'dark' form.

Occam's razor rules OK!

2004-12-07T21:43:00.000Z

It seems to me that current theories of the Universe defy the principle of Occam's razor. Each new hypothesis is added to overcome the difficulties raised by the last and lacks supporting experimental evidence.