Selected Questions-Answers From ALL Experts Astronomy Forum (Dark Matter Planets?)

Question: Scientists know that there must be more mass than what is visible in galaxies as they manage to hold themselves together despite not being enough ordinary matter, so they call it dark matter as it doesn't emit anything but is observable through its gravity. Then if this dark matter can generate gravity similar to ordinary matter then can it not interact with itself and make dark matter clumps that are gravitationally detectable. Like a dark matter planet? If this was true i imagine a dark matter planet would be detectable as it would skew the orbits of ordinary matter planets? - Puzzled

Answer:

The conception of dark matter planets or solar systems for that matter is dependent on how well we can distinguish exotic forms from ordinary forms. In the latter case one might reference Fritz Zwicky's measurements of galaxy clusters which  highlighted a ‘missing mass’. He found that the mass needed to bind a cluster of galaxies together gravitationally was at least ten times the apparent mass visible.  Around the same time there were observations of stellar motions in the galactic plane by Dutch astronomer Jan Oort. He found there had to be at least three times the mass visibly presenting in order for stars not to escape the galaxy and fly off into space.

What exactly constituted this 'missing mass'.? The short answer is we don't know but there a number of candidates. By the late 1970s (with Cygnus X-1), astronomers realized there were other forms of dark matter. Among the most discussed candidates were black holes, marking the end stage of evolution for very massive stars. In the black hole, the gravity is so strong that no light escapes and the mass typically is much greater than that of the Sun.

Currently, we are aware of a super black hole at the center of our galaxy with 9.7 billion times the mass of the Sun.  Can such an entity form planets? Hardly! It would more likely 'devour' them.

Dark matter generally occurs in either baryonic or non-baryonic forms, depending on whether the matter reacts with radiation or not. If it doesn’t, it’s non-baryonic. Baryons include protons and neutrons, while non-baryons include electrons and neutrinos.

Non-baryonic dark matter further breaks down into cold dark matter and hot dark matter. The terms hot and cold are not so much indicative of current temperatures, as the phase of the early universe at which the particular dark matter ‘decoupled’ from the hot radiation background. An early decoupling implies a higher ambient background radiation temperature of the primeval cosmos. A later decoupling correlates to a cooler temperature. Perhaps the most widely studied candidate of hot dark matter is the neutrino.

By contrast, cold dark matter candidates tend to have larger mass and amongst the most likely suspects are: gravitinos, magnetic monopoles, and primordial black holes. However, there are a couple of exceptions to this, which include: WIMPs and Axions.

How any of these entities could leave specific gravity signatures that distinguish any one from their dark counterparts is a matter of continued inquiry.  Until such signatures are identified and clarified there is little chance of even remotely confirming on the existence of  "dark matter planets". Especially if it is proposed that such a planet could orbit an ordinary matter (e.g. hot plasma) star.

It is certainly plausible that a dark matter object (like a small black hole) could "skew the orbit" of an ordinary matter planet - or star. But that a dark matter planet could exist within the confines of an ordinary matter solar system is another matter. And if such a solar system was entirely of dark matter, how would one detect it at all?

Your conjecture of dark matter clumps  spinning off from a much larger dark matter mass (e.g. proto- star)  evokes a takeoff on the nebular hypothesis of origin for our own solar system.  The problem is that while such an entity (dark matter proto-planet) might be possible, there is no evidence whatsoever it exists. For example, all of the hundreds of exoplanets found thus far have all been ordinary matter objects - no 'dark matter'.

This is not to say such planets will never be found, but rather the investment of time, technology an resources may be much more than current cost-benefit analyses allow.

Is There Really A "Discrepancy" In The Hubble Constant? Is It Truly A Constant?

According to Dennis Overbye, writing recently in the NY Times "there is a crisis brewing in the cosmos, or perhaps in the community of cosmologists". He adds that some astronomers believe  the universe seems to be expanding too fast.   Further, recent measurements of the distances and velocities of faraway galaxies don’t agree with a hard-won “standard model” of the cosmos that has prevailed for the past two decades. The latest result shows a 9 percent discrepancy in the value of the Hubble constant, which describes how fast the universe is expanding.

First, a bit of background: thanks to astronomer Edwin Hubble cosmology was put on a more secure observational footing on the basis of his "Hubble law". It is encapsulated by the graph shown below:

This relation between distance D  to an extra-galactic object  e.g. quasar, galaxy cluster) and its recessional velocity (v), has since come to be known as Hubble's law and is  expressed:

v = cz = HD

where H is known as the Hubble constant, c is the speed of light and z is the red shift.

This quantity z measures the extent to which spectral lines, say L1 and L2,  are shifted to the red  (longer wavelengths) compared to the normal spectrum, say of an element like hydrogen. The greater this shift the higher the velocity of recession.

The image below illustrates this for two extragalactic objects:



In fact 'H' is more technically the Hubble "scale factor".  The REAL Hubble constant (H o ) is the scale factor (a) divided by the distance in megaparsecs  MPC (km) where 1 parsec = 3.26 light years.

If then currently MPC (km)   =   3.08 x 10  ¹⁹     km/ Mpc  then:

H o =   a / MPC(km)   =  2.26 x 10 ^-18  s ^-1

Then the age of the cosmos can be obtained from:  t o =  1 / H o =

 (1 /   2.26 x 10 ^-18  s ^-1 )   =   4.4 x 10 ¹⁷  s   = 1.3 x 10 ¹⁰  yrs. or 13 billion years in age

The scale factor a, called the "Hubble constant",  is currently a »  70 km/ sec/Mpc. But as I reported last summer, e.g.

http://brane-space.blogspot.com/2016/06/arriving-at-hubble-constant.html

has since been refined to a = 72.8  km/ sec/Mpc.

Clearly then what we call the Hubble constant depends on the accuracy of a, and this in turn depends on the latest techniques to attain more exact values.  As I noted in the preceding link the newer,  more exact value has been based on refining the universe’s current expansion rate to unprecedented accuracy, reducing the uncertainty to only 2.4 percent.

However, an uncertainty of even just 2.4 percent means we cannot be talking about a real physical constant, but only an approximate factor that determines the proportionality value H in the Hubble law.  This is important to process before continuing.  My point is that the "discrepancy" with the standard model is a separate issue, because the standard model itself is still under scrutiny, although it's gained much more traction with the discovery of the Higgs boson.

This elicits the question of whether this small "mismatch" (Overbye's term)  is truly an indicator of  how well we know the cosmos. According to  Wendy Freedman of the University of Chicago, who has spent most of her career charting the size and growth of the universe:

“If it is real, we will learn new physics,”

Perhaps. But I don't think the 'new physics' will enter until we also are able to incorporate the role of dark energy, which has been identified as the primary agent responsible for the accelerated expansion. Relevant to this we invoke what can be called a cosmological "equation of state" (think of something like the equation of state for an ideal gas, e.g. P = nkT) for the vacuum energy presumed to underlie most theories of  dark energy . This is:

w = (Pressure/ energy density) = -1

One advantage is that this equation of state is consistent with Einstein's general theory of relativity - which one could say approaches the status of a 'basic law of physics'. 

In this case, the existence of a negative pressure is consistent with general relativity's allowance for a "repulsive gravity" - since any negative pressure has associated with it gravity that repels rather than attracts. (See, e.g. 'Supernovae, Dark Energy and the Accelerating Universe', by Saul Perlmutter, in Physics Today, April, 2003, p. 53.) Of course, simple algebra applied to the above also shows that the energy density would have to be negative, e.g. energy density =  - (pressure).

Specifically the term (r + 3p) acts as a source of gravity in general relativity, (where r = energy density).

 Set:  0 = (r + 3p),   then the pressure :

 p =  -r /3   (or  r  = - 3p)

 and if:  p <  (r /3) we have gravity that repels.

To ascertain the proportions of dark matter and dark energy one uses graphs derived from supernova  data with corrected apparent visual magnitude m v , redshift (z),   to give different combinations of  W _dark to W _matter over the range. However, only one of the graph combination bests fits the data. Currently this yields:

Wd_ark = 0.68 and  W_matter = 0.27


As a result,  astronomers have accepted that the universe consists of roughly 5 percent atomic matter by weight, 27 percent dark matter and 68 percent dark energy . The last is what's speeding up the cosmic expansion.

Back to the link above for my earlier post last summer citing a team led by Adam Riess of Johns Hopkins University and the Space Telescope Science Institute, using the Hubble Space Telescope and the giant Keck Telescope on Mauna Kea in Hawaii . They obtained a value with  only 2.4 percent uncertainty - but as I pointed out-   this is still nowhere near acceptable constant territory. Check any table of physical constants - actual ones, like the Newtonian G, or speed of light c - for comparison.

The claim of Overbye  in his piece is that this "made waves because it meant that, if true, the Hubble constant as observed today was now clearly incompatible with a result of the lower slower value of 67 inferred from data obtained in 2013 by the European Planck spacecraft of relic radiation from the Big Bang."

But how big were these "waves",  really? Those  Planck mission observations revealed the universe when it was only 380,000 years old  and these are considered "the gold standard of cosmology."  But how reliable and trustworthy is this gold standard?  Interestingly, whether the standard cosmic recipe might now need to be modified  depends on whom you talk to.

Personally, I side with the higher  H values because I place more confidence in the supernova data and observations, redshifts derived therefrom, than the Big Bang Plank observations. Heresy? Maybe, but there it is. Also, Prof.  Riess has admitted that the Planck mission measured the Hubble constant only indirectly as one of several parameters, i.e. in the standard model of the universe. So why would you place more faith in those measures than the supernovae data?

Bolstering this POV, another group called H0LiCOW (short for H0 Lenses in COSMOGRAIL’s Wellspring),  from the Max Planck Institute for Astrophysics in Garching, Germany, reported its own value of 72 km/ sec/Mpc , also inconsistent with the lower value from the Planck space mission’s analysis.  This interjects the question of whether the "Big Bang' results might themselves be spurious and based on as yet undetected systematic or other errors. Or, perhaps the Standard Model itself needs revision. (See addendum).

Stay tuned, because the issue isn't resolved yet, but for my money, the high z supernova data hold the key. Until I see much more consistency in the results from the "Big Bang"- Standard model teams.
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Addendum on the Standard Model- Higgs boson discovery:

The so-called 'Standard Model' is generally defined as the symmetry:

SU(3) x SU(2) X U(1)

where each of the above denotes a specific matrix, or more exactly a group. See, e.g.

http://brane-space.blogspot.com/2010/04/looking-at-groups.html

In the case of SU(2) we describe it as the "special unitary group" which has the form:

S =

(a.........-b*)
(b..........a*)

where a*, b* are complex conjugates and we have (aa* + b*b) = 1. Thus the elements of SU(2) are the unitary 2 x 2 matrices with DET (determinant) = 1. These groups thus define the behavior of a specific class of subatomic particles. Spontaneous symmetry breaking would therefore resolve this combination into constituent parts, e.g.: SU(3) associated with the 'color force' of quarks:

 SU(2) x U(1)

associated with the electro-weak force.

One possible symmetry breaking (quark -boson format) is:

SU(3) x SU(2) X U(1) -> SU(3) + SU(2) x U(1)

which would occur at a particular ambient temperature (T_qb) for the universe at some epoch (E_qb) in the past. In the foregoing, the synthesis of SU(2) and U(1) into the locally gauge invariant electro-weak theory requires a mechanism which confers mass to three vector bosons while leaving the photon massless. This 'mass-giving' mechanism is called the Higgs Field or Higgs mechanism, and it demands the existence of one or more massive, spin-0 bosons otherwise called Higgs bosons.

Enter now the putative discovery of the Higgs, thanks to the large hadron collider, which  was announced at CERN. Dr. Rolf Heuer, director general of CERN, while referring to the new discovery as "a historic milestone"  nevertheless cautioned that it was too soon to know for sure if the new particle (coming in at 125 billion electron volts) is actually the long sought particle.

The problem? The culmination of analyses of over 800 trillion proton-proton collisions over the 2 years leading up to the announcement generated a quandary. When buttonholed,  the physicists admitted they  actually knew little. The CERN results were mostly based on measurements of two or three of the dozen different ways, or “channels,” by which a Higgs boson could be produced and then decay. Worse, there were hints that some of the channels were overproducing the Higgs while others might have been underproducing. In either case, false positives or false negatives, one had to look askance at the initial results.

The upshot? There may not have been a real Higgs discovered but a spurious 'mirage' imitating some of its properties but more a confection of the data than based in reality. Also, assuming a genuine signal or find, it may not have been unique but only ONE of two or three different Higgs bosons. Much like the case of the neutrino, which was once believed to be one entity only, but we now know is THREE: the electron neutrino, the tau neutrino and the muon neutrino, see e.g. http://brane-space.blogspot.com/2012/06/solving-neutrino-puzzleand-matter.html

Arriving at a More Refined Hubble Constant

The Hubble constant is amongst the most critical values used in modern cosmology. Although it is referred to as a "constant" it is, in fact, subject to change based on changed (i.e. more up to date) data. The above pictogram shows basically the three steps by which its value is currently arrived at.

According to a report out of the Space Telescope Science Institute by Donna Weaver and Ray Villard a team under the aegis of  Nobel Laureate Adam Riess (of the Space Telescope Science Institute and Johns Hopkins University) ,  has made a discovery leading to an updated value for the Hubble constant. This has been based on refining the universe’s current expansion rate to unprecedented accuracy, reducing the uncertainty to only 2.4 percent. The team made the refinements by developing innovative techniques that improved the precision of distance measurements to faraway galaxies.

The results will appear soon in an upcoming issue of The Astrophysical Journal but interested readers can access the basic details here:

http://science.nasa.gov/science-news/science-at-nasa/1999/ast25may99_2/
 

The Riess et al team looked for galaxies containing both Cepheid stars and Type Ia supernovae. Cepheid stars pulsate at rates that correspond to their true brightness, which can be compared with their apparent brightness as seen from Earth to accurately determine their distance. Type Ia supernovae, another commonly used cosmic yardstick, are exploding stars that flare with the same brightness and are brilliant enough to be seen from relatively longer distances.

By measuring about 2,400 Cepheid stars in 19 galaxies and comparing the observed brightness of both types of stars, see e.g.

http://brane-space.blogspot.com/2011/08/tackling-intermediate-astronomy.html


they accurately measured their true brightness and calculated distances to roughly 300 Type Ia supernovae in far-flung galaxies.

The team then compared those distances with the expansion of space as measured by the stretching of light from receding galaxies. They used these two values to calculate how fast the universe expands with time, or the Hubble constant.

The improved Hubble constant value 45.5 miles (72.8 km) per second per megaparsec. (A megaparsec equals 3.26 million light-years.) The new value means the distance between cosmic objects will double in another 9.8 billion years.

This refined calibration presents a puzzle, however, because it does not quite match the expansion rate predicted for the universe from its trajectory seen shortly after the Big Bang. Measurements of the afterglow from the Big Bang by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency’s Planck satellite mission yield predictions which are 5 percent and 9 percent smaller for the Hubble constant, respectively.

“If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the big bang and use that understanding to predict how fast the universe should be expanding today,” said Riess. “However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today.”

Comparing the universe’s expansion rate with WMAP, Planck, and Hubble is like building a bridge, Riess explained. On the distant shore are the cosmic microwave background observations of the early universe. On the nearby shore are the measurements made by Riess’ team using Hubble.

“You start at two ends, and you expect to meet in the middle if all of your drawings are right and your measurements are right,” Riess said. “But now the ends are not quite meeting in the middle and we want to know why.”

There are a few possible explanations for the universe’s excessive speed. One possibility is that dark energy, already known to be accelerating the universe, may be shoving galaxies away from each other with even greater — or growing — strength.

Another idea is that the cosmos contained a new subatomic particle in its early history that traveled close to the speed of light. Such speedy particles are collectively referred to as “dark radiation” and include previously known particles like neutrinos. More energy from additional dark radiation could be throwing off the best efforts to predict today’s expansion rate from its post-Big Bang trajectory.

The boost in acceleration could also mean that dark matter possesses some weird, unexpected characteristics. Dark matter is the backbone of the universe upon which galaxies built themselves up into the large-scale structures seen today.

And finally, the speedier universe may be telling astronomers that Einstein’s theory of gravity is incomplete.

“We know so little about the dark parts of the universe, it’s important to measure how they push and pull on space over cosmic history,” said Lucas Macri of Texas A&M University in College Station, a key collaborator on the study.

The Hubble observations were made with Hubble’s sharp-eyed Wide Field Camera 3 (WFC3), and were conducted by the Supernova H0 for the Equation of State (SH0ES) team, which works to refine the accuracy of the Hubble constant to a precision that allows for a better understanding of the universe’s behavior.

The SH0ES team is still using Hubble to reduce the uncertainty in the Hubble constant even more, with a goal to reach an accuracy of 1 percent. Current telescopes such as the European Space Agency’s Gaia satellite, and future telescopes such as the James Webb Space Telescope (JWST), an infrared observatory, and the Wide Field Infrared Survey Telescope (WFIRST), also could help astronomers make better measurements of the expansion rate.

Before Hubble was launched in 1990, the estimates of the Hubble constant varied by a factor of two. In the late 1990s the Hubble Space Telescope Key Project on the Extragalactic Distance Scale refined the value of the Hubble constant to within an error of only 10 percent, accomplishing one of the telescope’s key goals. The SH0ES team has reduced the uncertainty in the Hubble constant value by 76 percent since beginning its quest in 2005.

---------------------
Source: Donna Weaver and Ray Villard, Space Telescope Science Institute
 

How Do We Educate GOOPr Morons?

Well, wouldn't you know it wouldn't take long for assorted fundagelical know-nothings to try to defend the moron Paul Broun, a current member of the House Science, Space and Technology Committee who actually has rejected 90% of modern science. (See, e.g. http://brane-space.blogspot.com/2012/10/congressman-moron-broun-science-is-from.html) To remind readers, Broun insisted that the Big Bang Theory, Embryology and Evolution are all "lies from the pit of Hell".

Now, let me make it abundantly clear here, especially for the occasional fundy readers who have difficulty parsing complex notions, and even the principle of basic free speech - that I've nothing against Broun saying whatever he wants to his congregation, and that he's entitled to whatever whacko beliefs he has in the context of that congregation. But he's not entitled to use his office as a member of a congressional Science, Space &Technology Committee to mouth bullshit and half-cracked, stupid theories of "creation".

Anyway, let's deal with Mr. "Straight Talk" Fundy and some of his comments. He bloviates:

"Evolution is an enabler of atheism. Evolutionary scientists likely would not admit that their goal is to give an alternate explanation of the origins of life, and thereby to give a foundation for atheism, but according to the Bible, that is exactly why the theory of evolution exists."

Well, I hate to disabuse this poor,  uninformed cuss but the theory of evolution is an "enabler" of nothing. It stands on its own scientific merits as I noted numerous times before and even showed the predictions which it confirms, including the presence of essentially the same cytochrome-c sequence in chimps and humans, the combination of the 2p and 2q chromosomes in apes to the '2' chromosome in humans, and the evolution of the foraminfera - for which we have a FULL evolutionary record.

Sadly, this guy's deficiency of education is also apparent in confusing evolution - the theory for the DEVELOPMENT of life via natural selection, with Abiogenesis - the theory of the ORIGIN of life. I mean - if a would-be critic isn't even able to tell evolution from Abiogenesis, what the hell use is his critique? It's just plain old garbage - useful only to flush down a toilet. Either you learn the differences between the scientific areas you're critiquing, or you shut up.

So, given he doesn't know dogshit about evolution, let's move on to the big Bang, where he babbles:

"So, what about this "Big Bang" crapola? Well, in view of the incredible order in the universe, it is difficult to draw any conclusion other than existence of a supernatural, superintelligent Being behind it all."

Hardly! THAT is an assumption which has to be proven. Meantime, his appeal to this "incredible order" in the universe again breaks down because his monumental ignorance. He refers to an "order" which manifests in about 0.001% of the cosmos but ignores the other 99.999% where NO order is evident, and indeed, for which something like 73% is dark energy and another 20% dark matter! (The rest being hot, ionized plasma).

Of course, if one has his or her head only in bibles there's no doubt there'll be no familiarity with the basic implements and instruments of modern cosmology. If this character had even the limited ability to read outside his one book, he'd learn about the Wilkinson Microwave Anisotropy Probe and other devices which have disclosed the dark energy in the cosmos.

One's only conclusion is that if some "supernatural' entity created the cosmos, he or It must've been BLIND! To have created so much DARKNESS, in dark energy and dark matter!

WTF good is a blind creator?

The blogger, having failed in his arguments has no choice but to use red herrings, i.e.

"As one scientist said, "You can lead a skeptical astronomer to order but you cannot make him think." Even the agnostic, Immanuel Kant , wrote: "Two things fill the mind with ever new and increasing admiration and awe, the oftener and more steadily we reflect on them: the starry heavens above and the moral law within me."

Well, first NO scientist I am aware of would've made the critical statement about skepticism, the fundy invokes above. The reason is that skepticism is a healthy and integral part of science. In fact, no one can truly claim to have a scientific temperament if he doesn't also have a skeptical mind. He must question all claims, and also the evidence, if it doesn't pass muster.  As for Kant, let's bear in mind he lived hundreds of years BEFORE the discovery of dark energy and dark matter (in the 1990s), so obviously would have been enthralled by the perception of superficial order. Meanwhile, the fundies' favorite book as a reliable repository of scientific knowledge FAILS because it can't pass the most rudimentary science test!

Consider the initial major error in Genesis,(Gen.:1: 1-5)

“In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters. And God said, Let there be light and there was light. And God saw the light, that it was good: and God divided the light from the darkness. And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day”

It is clear that the “light” referred to in the last three sentences is none other than the SUN. However, it is clear from reading each line through that the Earth was supposedly made BEFORE the Sun. (E.g. Earth without form, darkness upon face of the deep).


However, this is physically impossible! We know from modern astrophysics that the solar proto-nebula had to collapse first to yield the SUN. (No planets, since they had yet to spin off the collapsing nebular cloud – it hadn’t cooled enough to allow it). As the proto-solar nebula collapsed it also began spinning and gained angular momentum. This angular momentum was then transferred to regions of the nebula that cooled and separated from the whole, and these regions became separate clouds of dust and gas that aggregated into the planets.


Under a combination of electrostatic attraction (between larger charged particles) and gravity (attracting the whole mass from the center of the cloud) each planet was formed as what we call a “planetesimal”. As more angular momentum was transferred – the planetesimal’s (each one) acquired their own spin (in a period of revolution) and specific shapes. The giant planets (e.g. Jupiter, Saturn, Neptune, Uranus) garnered more spin momentum than the more dense, terrestrial planets. Thus Jupiter’s planetesimal ended up as an oblate spheroid with diameter of about 88,000 mile and rotating rapidly with a day of ~ 10 hours. Earth meanwhile ended up as a relatively spherical orb with diameter of ~ 8,000 miles and day approaching approach 24 hrs. Mars ended up in a similar shape to that of Earth and a diameter of 4200 miles and day ~ 24 hours.


Thus, the Earth spun off about 1.1 billion years after the solar nebula fully collapsed, and it could not have come BEFORE the Sun. Indeed, the absence of the central mass of the Sun, or ~ 10 ^33 kilograms, would have meant the Earth- if made with no Sun present- would instantly have been hurled into a direction toward the constellation Hercules at 12 miles per second with no central mass to keep it in check.

  Hamstrung he then babbles more balderdash:

 "Modern astronomers are again faced with the evidence of God for a Creator of the cosmos .  

Alas, given the majority proportions of dark energy and dark matter we are faced with NO such evidence. One must wonder what ale or spiked pale beer or moonshine this guy is drinking to entertain such fantasies.  

And to top it off we behold this nonsense:

 "Ironically, the Big Bang theory does not explain the "bang." It takes current conditions and attempts to count backward in time. It assumes that all natural laws have remained the same since the beginning of the universe, but even then it cannot explain how energy could reside in a singularity or what made it explode.  

First, the term "Big Bang" does not refer to a "bang" in any literal sense. There could have been no "bang" because there was no space for it to have exploded into. Hence, it is not an explosion but an expansion. This expansion was initiated by the eruption of negative (vacuum) energy. In its inception, from negative vacuum energy, then space-time was actually created too.  (Let's also be aware that the initial singularity is actually a kind of misnomer.  It technically refers to a point inside the light cone of a point in de Sitter space.  However, the point itself and its light cone are in fact the 'big bang' of the Friedmann model for which the scale factor goes to zero. But it is not 'singular').

 Second, the reference to "current conditions" only applies strictly to THERMODYNAMICS or a thermodynamic basis. (As shown in the Appendix of Steven Weinberg's 'First Three Minutes'. Thus Weinberg uses the fact that the radius of the universe is inversely proportional to the temperature, T, and hence the mass density rho(t) is inversely proportional to R(t) to the 4th power).

Thus, we can - from thermodynamics- arrive at the original temperature (or fairly close to the instant of inception) by taking the current 2.7 K microwave background and extrapolating back using black body radiation principles and basic statistical mechanics.  

Third, obviously it can't have assumed all natural laws "remained the same since the beginning of the universe" because the temperatures back then would not have allowed it! In the earliest instants we had temperatures of over a trillion degrees K so how could any natural laws exist such as recognized today? The ambient temperatures wouldn't even have been cool enough to permit the formation of extended matter or mass systems, or even ATOMS! Thus, Newton's law of universal gravitation wouldn't even have applied! Of course, none of Newton's law of motion would have either!

 His last complaint discloses further entrenched ignorance. Again, the Big Bang was not an "explosion" but an expansion which also initiated space-time. The energy resident in the initial singularity has to be treated in two parts, one applicable to conformal space-time and the other non-conformal. Interested readers might want to get hold of the excellent paper: 'Universe Before Planck Time - A Quantum Gravity Model' in Physical Review D, Vol. 28, p. 756 where T. Padmanabhan shows how the universe could be incepted from an initial quantum fluctuation.

 This is possible when the conformal part of space-time is treated as a quantum variable.   Padmanabhan does this beautifully, by using a quantum harmonic oscillator model and using integrals related to the 'action' (J) as a function of time. He then solves for the 'expansion factor' S(t) using two separate energy equations from which he's able to track the energy associated with the singularity.  

For those who might not be able to get hold of his paper, my 2009 blog on vacuum energy and fluctuations is still available: http://brane-space.blogspot.com/2009/09/another-case-of-misapplied-causality-to.html  

What we can see from this is that fundy bloggers who know nothing about quantum mechanics, cosmology or evolution need to keep their comments confined to their good books and refrain from expostulaing on things beyond their ken, for which they have not one scintilla of background.  

Hey, that's good advice for Paul Broun too!

Dark Matter DOES Exist - In Space!

The recent article appearing in The Economist ('The Dark at the End of the Tunnel?', Sept. 17, p. 85) appeared to suggest that the evidence for dark matter is only now beginning to be accepted by a certain skeptic faction of physicists, based on recent experiments at the Gran Sasso Laboratory in central Italy. This is based on the first empirical evidence for WIMPs or weakly interacting massive particles (see, e.g. 'To Catch A WIMP', in SCIENCE, Vol. 275, March 21, 1997, p. 1736).

But in fact, the evidence for dar matter is already essentially signed, sealed and delivered, and even The Economist acknowledges (ibid.):

"Physicists are pretty confident dark matter exists. Astronomical observations first made in the 1930s show there is not nearly enough ordinary matter to hold galaxies together as they spin around."

Indeed, this is spot-on correct.

The detection of extended dark matter can be traced back to 1933, when Fritz Zwicky's measurements of galaxy clusters highlighted a ‘missing mass’. He found that the mass needed to bind a cluster of galaxies together gravitationally was at least ten times the apparent mass visible. This mass, because it was inferred but not directly detectable, became the first ‘dark matter’. Around the same time there were observations of stellar motions in the galactic plane by Dutch astronomer Jan Oort. He found there had to be at least three times the mass visibly presenting in order for stars not to escape the galaxy and fly off into space.

By the late 1970s, astronomers realized there were other forms of dark matter. Among the most discussed candidates were black holes, marking the end stage of evolution for very massive stars. In the black hole, the gravity is so strong that no light escapes and the mass typically is much greater than that of the Sun. These objects can only be detected indirectly, e.g. as a member of a binary (double) star system, to infer its presence from the intense x-rays given off when the companion star’s gaseous layers are sucked into it.

Dark matter itself occurs in either baryonic or non-baryonic forms, depending on whether the matter reacts with radiation or not. If it doesn’t, it’s non-baryonic. Baryons include protons and neutrons, while non-baryons include electrons and neutrinos.

Non-baryonic dark matter further breaks down into cold dark matter and hot dark matter. The terms hot and cold are not so much indicative of current temperatures, as the phase of the early universe at which the particular dark matter ‘decoupled’ from the hot radiation background. An early decoupling implies a higher ambient background radiation temperature of the primeval cosmos. A later decoupling correlates to a cooler temperature. Perhaps the most widely studied candidate of hot dark matter is the neutrino.

By contrast, cold dark matter candidates tend to have larger mass and amongst the most likely suspects are: gravitinos, magnetic monopoles, and primordial black holes. However, there are a couple of exceptions to this, which include: WIMPs and Axions.

The issue then in The Economist article is not so much whether dark matter does indeed exist, but whether one particular form for cold dark matter (the WIMP) has actually been detected at the Gran Sasso Lab (in an experiment abbreviated 'DAMA')

In the DAMA experiments, conducted some 1,400 meters below Gran Sasso, physicists have searched for (electro-) weak force mediated collisions between terrestrial atoms and WIMPs from the dark matter halo of the Milky Way. If such collisions actually occur, then they should be able to cause recoils of the atomic nuclei. With the proper apparatus such recoils ought to be observed.

In the case of the DAMA experiments, a 250 kg (550 lb.) crystal of sodium iodide is used, and the recoils measured within it. More than 15 years of operation have resulted in hundreds of thousands of collisions being recorded - though most have not been caused by dark matter. The lead investigator, Rita Bernabei of the University of Rome, still can't tell which of the recorded events are caused by WIMPS but she claims to see a discernible pattern. That is, every year the number of collisions rises until it peaks in May, and every year the collision frequency minimized in November. Bernabei believes this to be strong evidence some of the collisions arise from interactions with WIMPS because the motion of the Earth would be added to the speed with which the solar system moves through the galactic halo in the summer, while it would be subtracted in the winter. (Recall here from the Basic and Intermediate Astronomy blogs, that the Earth is moving faster as it approaches the perihelion of its orbit in January, while it'd be moving slower as it approaches aphelion in July).

But, of course, not everyone agrees , nor should they! Every cyclic correlation must be treated with skepticism and suspicion since the most classic case of false correlation ever occurred more than forty years ago when UFO observations were found to increase significantly with the oppositions of Mars. Did these mean more UFOs were spaceships arriving from Mars at each opposition - because at that point Mars was closer to Earth? Obviously not! But it shows the dangers inherent in not filtering out all possible signals. In the case of the "Martian" Opposition UFOs, they were found to be merely statistical coincidences. The simplest explanation? Mars appeared so much brighter at its opposition that millions of people around the Earth just mistook it for a "UFO"! Don't laugh! When I used to investigate UFOs as a pastime in Barbados, most of the time it was the planet Venus that had been wrongly perceived!

Lastly, other alternative experimental setups may be more able to ferret out real WIMP collisions. One example, from the Max Planck Institute, uses crystals of calcium tungstate cooled to within a few thousandths of a degree of absolute zero. Special thermometers are then introduced to detect any minuscule temperature increases expected to occur when subatomic particles collide with any of the Earth-components of the material and heat the material up. The investigators believe they can recognize the WIMPs by tiny flashes of light generated in each collision - as well as heat. (Dark matter collisions produce less light than non-dark matter collisions that generate the same amount of heat)

Stay tuned!

Initial Conditions of the Big Bang?

In a recent issue (Oct.-Nov.) of the Intertel journal, INTEGRA, Ken Wear asks:

“Supposing the Big Bang theory is correct, what were the initial conditions that produced it?”

This can be approached in a more or less practical way by treating the ‘Big Bang’ as a solution to Einstein’s tensor (field) equations. (See, e.g. ‘Quantum Field Theory – A Modern Introduction’, by Michio Kaku, p. 643):

As per the 2.7K isotropic, microwave background radiation, we assume radial symmetry for the metric tensor – for which we adopt a Robertson-Walker form. This omits all angular dependence and leaves a function of form R(t) which sets the scale and defines an ‘effective radius’ of the universe.

We have:

ds^2 = dx^u g_uv dx^u = dt^2 – R^2(t) [ (dr^2/ 1 – kr^2) + r^2 d (S)^2]

where d(S)^2 is the solid angle differential and k = const.

Associate with this a fluid of average density rho(t) and internal pressure p(t)

The energy-momentum tensor becomes: T_o^0 = rho, T_I^I = -p

with all other components zero.

After inserting these into the Einstein field eqns.

(dR/dt /R)^2 = (8 pi)/ 3 (G_N rho) – k / R^2

whence:

(d^2R/ dt^2 )/ R = - 4 pi G_N (p + rho/3) + LAMBDA/ 3

After setting the cosmological constant (LAMBDA) = 0 and eliminating rho, one obtains as a solution for R (radius of universe as power law function).

R= (9/ 2GM)^1/3 [t ^2/3]

One can deduce from this (ibid, p. 645) that at the Planck energy of 10^19 GeV (giga -electron volts) of energy, the symmetries of gauge theory were still united in a single force. This is at a cosmic age of 10^-44 s.

This represents the closest approach of physics to the cosmic singularity (t = 0) but still defines the ‘Big Bang’ since the explosion is already underway and forces are still unified.

This continues as other symmetries ’break’ one by one, leading to the radiation dominated era. (Described by the Bose-Einstein distribution function, which perfectly applies to the expanding pure photon gas).

The fact that the ‘Big Bang’ can be obtained as a solution to one version of Einstein’s tensor equations, discloses that QM and GR equations certainly don’t ‘blow up’ and are impossible to use.

Mr. Wear then makes the assertion that it “would certainly be a violation of our concepts of cause and effect to say that suddenly, out of nothing….came this cataclysmic explosion”


But again, as I noted earlier, cause and effect notions are of little use. What we need instead are necessary and sufficient conditions for the event to occur - which by the way, is not an ‘explosion”! I refer Mr. Wear to ASTRONOMY magazine, May, 2007, ‘5 Things You Need To Know’, p. 31:

“The Big Bang wasn’t any kind of explosion. It was closer to an unfolding or creation of matter, energy, time and space itself. What would actually have been a much better name is ‘expanding universe theory’.”

As to how spontaneous cosmic inception can occur, this was referenced by T. Padmanabhan, 1983, ‘Universe Before Planck Time – A Quantum Gravity Model', in Physical Review D, Vol. 28, No. 4, p. 756.

To fix ideas, we are interested in first determining the gravitational action, and from this whether acausal determinism is more or less likely to apply. For any action S(g) if

S(g) < < h (the Planck constant)

where h = 6256 x 10^-34 J/s

we may be sure that classical causality is out the window and we are dealing with acausal determinism

If S(g) > > h

the converse holds.

To evaluate S(g) as Padmanabhan shows (op. cit.) , we need V the 4-volume of the space-time manifold for which we choose a de Sitter space, in the first approximation.

We have

S(g) = c^3/ (16 pi G) INT_V R(-g)^1/2 d^4x


where G is the gravitational constant, c is the speed of light, the integral (INT) is over the 4-volume V with the differential (d^4x) to match.

In the big bang model one takes V as the spatial volume enclosed by the particle horizon, and bounded by the time span (t) of the universe. Thus, at any epoch t for k = 0,

S(g) ~ t^1/2

The particle horizon is defined by

rS(g) = 2 ct

Einstein's gravitational equations (with cosmological term, for the sake of generality) are

R ( i k ) - (1 / 2) g ( i k ) R = T ( i k ) + lambda g ( i k )

where the ‘lambda’ denotes the cosmological constant. For de Sitter space it is equal to:

(n – 1)(n – 2)/ [2 a^2]

where a is a scale factor, and n denoted the dimension (4) of the volume under consideration. R(ik) is the Ricci tensor.

Now for S(g) ~ t^1/2, R (the scalar curvature of de Sitter space) = 0, so S(g) = 0

However, the above happens because the Einstein tensor (T_ik) has trace = 0 in the early universe. The ‘trace’ is the sum of the diagonal elements of a tensor, e.g.

Tr(M) = 0

where M =

[0 1 0 ]
[0 -1 0 ]
[0 0 1 ]


This means the limits must definitely be for acausal determinism, NOT classical – including classical causality.

Wear also alludes to a “sequence of oscillations” (ibid.) but this is egregious, since there will be no oscillations, as the universe is not only forever expanding but accelerating in its expansion.

Universes that re-collapse (decelerate), expand forever with zero limiting velocity (e.g. v uniform) or expand forever with positive limiting velocity (accelerate) are called in turn: 'closed' (can have curvature k = +1); 'critical' (k =0) or 'open' (can be k = -1), respectively

Now, to determine whether any F-R-W (Friedmann-Robertson-Walker) cosmological template leads to deceleration or not, we need to find the cosmic density parameter:

OMEGA = rho / rho_c

where the denominator refers to the critical density. Thus if:

rho > rho_ c

(c = critical)

then the cosmic density is able to reverse the expansion (e.g. decelerate it) and conceivably usher in a new cycle. (New Big bang etc.) The observations that help determine how large OMEGA is, come mainly from observing galaxy clusters in different directions in space and obtaining a density estimate from them.

Current data, e.g. from Boomerang and other satellite detectors shows that OMEGA ~ 0.3 or that:

rho = 0.3 (rho_c)

I.e. that rho < rho_ c, so there is no danger of the cosmos decelerating.

Precision measurements of the cosmic microwave background (CMB), including data from the Wilkinson Microwave Anisotropy Probe (WMAP), have recently provided further evidence for dark energy. The same is true of data from two extensive projects charting the large-scale distribution of galaxies - the Two-Degree Field (2DF) and Sloan Digital Sky Survey (SDSS).

The curves from other data with corrected apparent magnitude v. redshift (z) give different combinations of OMEAG_dark to OMEGA_matter over the range. However, only one of the graph combinations bests fits the data:

OMEGA_dark = 0.65 and OMEGA_matter = 0.35

Corresponding to an expansion accelerating for the last 6 million years- with much more dark energy involved (~ 0.65) than ordinary matter.

When the predictions of the different theoretical models are combined with the best measurements of the cosmic microwave background, galaxy clustering and supernova distances, we find that:

0.62 < OMEGA_dark < 0.76,

where OMEGA_dark = rho_dark/ rho_c, and -1.3 < w < -0.9.

In tandem, the numbers show unequivocally that dark energy is the acceleration agent, and in addition that dark energy comprises the lion’s share of what constitutes the cosmos (~ 73%).

In addition, all of this data is firmly backed up by earlier Boomerang (balloon) data that – when plotted on a power spectrum- discloses two adjacent ‘humps’ one a bit higher than the other. The “first acoustic peak” and the “second acoustic peak” fit uncannily to the sort of spherical harmonic function that describes a particular plasma condition. In this case, one that conforms to the supernova-derived values of OMEGA (d, m). (See: ‘Balloon Measurements of the Cosmic Microwave Background Strongly Favor a Flat Cosmos’, in Physics Today, July 2000, p. 7 and 'Supernovae, Dark Energy and the Accelerating Universe', by Saul Perlmutter, in Physics Today, April, 2003, p. 53)


Lastly, astronomers make no “claim” that galaxies are moving apart with increasing velocities. We have actual data that this is so, and it’s based on the basic physics of the Doppler effect.



-----------------------! L1 -------! L2----

---!----------!------------------
L1(o) L2(o)

Thus, in the above pictograph, lines L1(o) and L2(o) are the observed, redshifted (by some number of nanometers) spectral lines for some distant object such that:

v = cz

Where V denotes the velocity of recession, c is the speed of light, and z is the red shift

z = {L2(o)/ L2} - 1

Note again that L2 is the (lab-emission) standard line and L2(o) the observed line wavelength. If z > 0 we say the line is Doppler-effect redshift and receding.

To illustrate, say the hydrogen alpha line (emitted at 656.3 nm, e.g. L2 = 656.3 nm) is redshifted in some distant object to 666 nm (L2(o)). Then we have:

z = 1.015 – 1.000 = 0.015

This translates to a recessional velocity: v = (3 x 10 8 m/s) (0.015) = 4.5 x 10^6 m/s

As to Wear’s claim that it “may be difficult to place credence in such observations over a comparatively brief interval of time”, perhaps, but this “brief interval” is all we have to work with. What, will he dismiss all our painstakingly obtained date (including from the new CERN large hadron collider) because they were obtained over brief intervals? This isn’t the way a Realist works, but it is certainly the modus operandi for an Idealist.