Who put the Bang in Big Bang?

Back from the frozen North, having had a very nice time over Christmas, I thought it was time to reactivate my blog and to redress the rather shameful lack of science on what is supposed to be a science blog. Rather than writing a brand new post, though, I’m going to cheat like a TV Chef by sticking up something that I did earlier. I’ve  had the following piece floating around on my laptop for a while so I thought I’d rehash it and post it on here. It is based on an article that was published in a heavily revised and shortened form in New Scientist in 2007, where it attracted some splenetic responses despite there not being anything particular controversial in it! It’s not particularly topical, but there you go. The television is full of repeats these days too.

Around twenty-five years ago a young physicist came up with what seemed at first to be an absurd idea: that, for a brief moment in the very distant past, just after the Big Bang, something weird happened to gravity that made it push rather than pull.  During this time the Universe went through an ultra-short episode of ultra-fast expansion. The physicist in question, Alan Guth, couldn’t prove that this “inflation” had happened nor could he suggest a compelling physical reason why it should, but the idea seemed nevertheless to solve several major problems in cosmology.

Twenty five years later on, Guth is a professor at MIT and inflation is now well established as an essential component of the standard model of cosmology. But should it be? After all, we still don’t know what caused it and there is little direct evidence that it actually took place. Data from probes of the cosmic microwave background seem to be consistent with the idea that inflation happened, but how confident can we be that it is really a part of the Universe’s history?

According to the Big Bang theory, the Universe was born in a dense fireball which has been expanding and cooling for about 14 billion years. The basic elements of this theory have been in place for over eighty years, but it is only in the last decade or so that a detailed model has been constructed which fits most of the available observations with reasonable precision. The problem is that the Big Bang model is seriously incomplete. The fact that we do not understand the nature of the dark matter and dark energy that appears to fill the Universe is a serious shortcoming. Even worse, we have no way at all of describing the very beginning of the Universe, which appears in the equations used by cosmologists as a “singularity”- a point of infinite density that defies any sensible theoretical calculation. We have no way to define a priori the initial conditions that determine the subsequent evolution of the Big Bang, so we have to try to infer from observations, rather than deduce by theory, the parameters that govern it.

The establishment of the new standard model (known in the trade as the “concordance” cosmology) is now allowing astrophysicists to turn back the clock in order to understand the very early stages of the Universe’s history and hopefully to understand the answer to the ultimate question of what happened at the Big Bang itself and thus answer the question “How did the Universe Begin?”

Paradoxically, it is observations on the largest scales accessible to technology that provide the best clues about the earliest stages of cosmic evolution. In effect, the Universe acts like a microscope: primordial structures smaller than atoms are blown up to astronomical scales by the expansion of the Universe. This also allows particle physicists to use cosmological observations to probe structures too small to be resolved in laboratory experiments.

Our ability to reconstruct the history of our Universe, or at least to attempt this feat, depends on the fact that light travels with a finite speed. The further away we see a light source, the further back in time its light was emitted. We can now observe light from stars in distant galaxies emitted when the Universe was less than one-sixth of its current size. In fact we can see even further back than this using microwave radiation rather than optical light. Our Universe is bathed in a faint glow of microwaves produced when it was about one-thousandth of its current size and had a temperature of thousands of degrees, rather than the chilly three degrees above absolute zero that characterizes the present-day Universe. The existence of this cosmic background radiation is one of the key pieces of evidence in favour of the Big Bang model; it was first detected in 1964 by Arno Penzias and Robert Wilson who subsequently won the Nobel Prize for their discovery.

The process by which the standard cosmological model was assembled has been a gradual one, but it culminated with recent results from the Wilkinson Microwave Anisotropy Probe (WMAP). For several years this satellite has been mapping the properties of the cosmic microwave background and how it varies across the sky. Small variations in the temperature of the sky result from sound waves excited in the hot plasma of the primordial fireball. These have characteristic properties that allow us to probe the early Universe in much the same way that solar astronomers use observations of the surface of the Sun to understand its inner structure,  a technique known as helioseismology. The detection of the primaeval sound waves is one of the triumphs of modern cosmology, not least because their amplitude tells us precisely how loud the Big Bang really was.

The pattern of fluctuations in the cosmic radiation also allows us to probe one of the exciting predictions of Einstein’s general theory of relativity: that space should be curved by the presence of matter or energy. Measurements from WMAP reveal that our Universe is very special: it has very little curvature, and so has a very finely balanced energy budget: the positive energy of the expansion almost exactly cancels the negative energy relating of gravitational attraction. The Universe is (very nearly) flat.

The observed geometry of the Universe provides a strong piece of evidence that there is an mysterious and overwhelming preponderance of dark stuff in our Universe. We can’t see this dark matter and dark energy directly, but we know it must be there because we know the overall budget is balanced. If only economics were as simple as physics.

Computer Simulation of the Cosmic Web

The concordance cosmology has been constructed not only from observations of the cosmic microwave background, but also using hints supplied by observations of distant supernovae and by the so-called “cosmic web” – the pattern seen in the large-scale distribution of galaxies which appears to match the properties calculated from computer simulations like the one shown above, courtesy of Volker Springel. The picture that has emerged to account for these disparate clues is consistent with the idea that the Universe is dominated by a blend of dark energy and dark matter, and in which the early stages of cosmic evolution involved an episode of accelerated expansion called inflation.

A quarter of a century ago, our understanding of the state of the Universe was much less precise than today’s concordance cosmology. In those days it was a domain in which theoretical speculation dominated over measurement and observation. Available technology simply wasn’t up to the task of performing large-scale galaxy surveys or detecting slight ripples in the cosmic microwave background. The lack of stringent experimental constraints made cosmology a theorists’ paradise in which many imaginative and esoteric ideas blossomed. Not all of these survived to be included in the concordance model, but inflation proved to be one of the hardiest (and indeed most beautiful) flowers in the cosmological garden.

Although some of the concepts involved had been formulated in the 1970s by Alexei Starobinsky, it was Alan Guth who in 1981 produced the paper in which the inflationary Universe picture first crystallized. At this time cosmologists didn’t know that the Universe was as flat as we now think it to be, but it was still a puzzle to understand why it was even anywhere near flat. There was no particular reason why the Universe should not be extremely curved. After all, the great theoretical breakthrough of Einstein’s general theory of relativity was the realization that space could be curved. Wasn’t it a bit strange that after all the effort needed to establish the connection between energy and curvature, our Universe decided to be flat? Of all the possible initial conditions for the Universe, isn’t this very improbable? As well as being nearly flat, our Universe is also astonishingly smooth. Although it contains galaxies that cluster into immense chains over a hundred million light years long, on scales of billions of light years it is almost featureless. This also seems surprising. Why is the celestial tablecloth so immaculately ironed?

Guth grappled with these questions and realized that they could be resolved rather elegantly if only the force of gravity could be persuaded to change its sign for a very short time just after the Big Bang. If gravity could push rather than pull, then the expansion of the Universe could speed up rather than slow down. Then the Universe could inflate by an enormous factor (1060 or more) in next to no time and, even if it were initially curved and wrinkled, all memory of this messy starting configuration would be lost. Our present-day Universe would be very flat and very smooth no matter how it had started out.

But how could this bizarre period of anti-gravity be realized? Guth hit upon a simple physical mechanism by which inflation might just work in practice. It relied on the fact that in the extreme conditions pertaining just after the Big Bang, matter does not behave according to the classical laws describing gases and liquids but instead must be described by quantum field theory. The simplest type of quantum field is called a scalar field; such objects are associated with particles that have no spin. Modern particle theory involves many scalar fields which are not observed in low-energy interactions, but which may well dominate affairs at the extreme energies of the primordial fireball.

Classical fluids can undergo what is called a phase transition if they are heated or cooled. Water for example, exists in the form of steam at high temperature but it condenses into a liquid as it cools. A similar thing happens with scalar fields: their configuration is expected to change as the Universe expands and cools. Phase transitions do not happen instantaneously, however, and sometimes the substance involved gets trapped in an uncomfortable state in between where it was and where it wants to be. Guth realized that if a scalar field got stuck in such a “false” state, energy – in a form known as vacuum energy – could become available to drive the Universe into accelerated expansion.We don’t know which scalar field of the many that may exist theoretically is responsible for generating inflation, but whatever it is, it is now dubbed the inflaton.

This mechanism is an echo of a much earlier idea introduced to the world of cosmology by Albert Einstein in 1916. He didn’t use the term vacuum energy; he called it a cosmological constant. He also didn’t imagine that it arose from quantum fields but considered it to be a modification of the law of gravity. Nevertheless, Einstein’s cosmological constant idea was incorporated by Willem de Sitter into a theoretical model of an accelerating Universe. This is essentially the same mathematics that is used in modern inflationary cosmology.  The connection between scalar fields and the cosmological constant may also eventually explain why our Universe seems to be accelerating now, but that would require a scalar field with a much lower effective energy scale than that required to drive inflation. Perhaps dark energy is some kind of shadow of the inflaton

Guth wasn’t the sole creator of inflation. Andy Albrecht and Paul Steinhardt, Andrei Linde, Alexei Starobinsky, and many others, produced different and, in some cases, more compelling variations on the basic theme. It was almost as if it was an idea whose time had come. Suddenly inflation was an indispensable part of cosmological theory. Literally hundreds of versions of it appeared in the leading scientific journals: old inflation, new inflation, chaotic inflation, extended inflation, and so on. Out of this activity came the realization that a phase transition as such wasn’t really necessary, all that mattered was that the field should find itself in a configuration where the vacuum energy dominated. It was also realized that other theories not involving scalar fields could behave as if they did. Modified gravity theories or theories with extra space-time dimensions provide ways of mimicking scalar fields with rather different physics. And if inflation could work with one scalar field, why not have inflation with two or more? The only problem was that there wasn’t a shred of evidence that inflation had actually happened.

This episode provides a fascinating glimpse into the historical and sociological development of cosmology in the eighties and nineties. Inflation is undoubtedly a beautiful idea. But the problems it solves were theoretical problems, not observational ones. For example, the apparent fine-tuning of the flatness of the Universe can be traced back to the absence of a theory of initial conditions for the Universe. Inflation turns an initially curved universe into a flat one, but the fact that the Universe appears to be flat doesn’t prove that inflation happened. There are initial conditions that lead to present-day flatness even without the intervention of an inflationary epoch. One might argue that these are special and therefore “improbable”, and consequently that it is more probable that inflation happened than that it didn’t. But on the other hand, without a proper theory of the initial conditions, how can we say which are more probable? Based on this kind of argument alone, we would probably never really know whether we live in an inflationary Universe or not.

But there is another thread in the story of inflation that makes it much more compelling as a scientific theory because it makes direct contact with observations. Although it was not the original motivation for the idea, Guth and others realized very early on that if a scalar field were responsible for inflation then it should be governed by the usual rules governing quantum fields. One of the things that quantum physics tells us is that nothing evolves entirely smoothly. Heisenberg’s famous Uncertainty Principle imposes a degree of unpredictability of the behaviour of the inflaton. The most important ramification of this is that although inflation smooths away any primordial wrinkles in the fabric of space-time, in the process it lays down others of its own. The inflationary wrinkles are really ripples, and are caused by wave-like fluctuations in the density of matter travelling through the Universe like sound waves travelling through air. Without these fluctuations the cosmos would be smooth and featureless, containing no variations in density or pressure and therefore no sound waves. Even if it began in a fireball, such a Universe would be silent. Inflation puts the Bang in Big Bang.

The acoustic oscillations generated by inflation have a broad spectrum (they comprise oscillations with a wide range of wavelengths), they are of small amplitude (about one hundred thousandth of the background); they are spatially random and have Gaussian statistics (like waves on the surface of the sea; this is the most disordered state); they are adiabatic (matter and radiation fluctuate together) and they are formed coherently.  This last point is perhaps the most important. Because inflation happens so rapidly all of the acoustic “modes” are excited at the same time. Hitting a metal pipe with a hammer generates a wide range of sound frequencies, but all the different modes of the start their oscillations at the same time. The result is not just random noise but something moderately tuneful. The Big Bang wasn’t exactly melodic, but there is a discernible relic of the coherent nature of the sound waves in the pattern of cosmic microwave temperature fluctuations seen by WMAP. The acoustic peaks seen in the WMAP angular spectrum  provide compelling evidence that whatever generated the pattern did so coherently.
 

There are very few alternative theories on the table that are capable of reproducing the WMAP results. Some interesting possibilities have emerged recently from string theory. Since this theory requires more space-time dimensions than the four we are used to, something has to be done with the extra ones we don’t observe. They could be wrapped up so small we can’t perceive them. Or, as is assumed in braneworld cosmologies our four-dimensional universe exists as a subspace (called a “brane”) embedded within a larger dimensional space; we don’t see the extra dimensions because we are confined on the subspace. These ideas may one day lead to a viable alternative to inflationary orthodoxy. But it is early days and not all the calculations needed to establish this theory have yet been done. In any case, not every cosmologist feels the urge to make cosmology consistent with string theory, which has even less evidence in favour of it than inflation. Some of the wilder outpourings of string-inspired cosmology seem to me to be the physics equivalent of nausea-induced vomiting.

So did inflation really happen? Does WMAP prove it? Will we ever know?

It is difficult to talk sensibly about scientific proof of phenomena that are so far removed from everyday experience. At what level can we prove anything in astronomy, even on the relatively small scale of the Solar System? We all accept that the Earth goes around the Sun, but do we really even know for sure that the Universe is expanding? I would say that the latter hypothesis has survived so many tests and is consistent with so many other aspects of cosmology that it has become, for pragmatic reasons, an indispensable part our world view. I would hesitate, though, to say that it was proven beyond all reasonable doubt. The same goes for inflation. It is a beautiful idea that fits snugly within the standard cosmological and binds many parts of it together. But that doesn’t necessarily make it true. Many theories are beautiful, but that is not sufficient to prove them right. When generating theoretical ideas scientists should be fearlessly radical, but when it comes to interpreting evidence we should all be unflinchingly conservative. WMAP has also provided a tantalizing glimpse into the future of cosmology, and yet more stringent tests of the standard framework that currently underpins it. Primordial fluctuations produce not only a pattern of temperature variations over the sky, but also a corresponding pattern of polarization. This is fiendishly difficult to measure, partly because it is such a weak signal (only a few percent of the temperature signal) and partly because the primordial microwaves are heavily polluted by polarized radiation from our own Galaxy. Although WMAP achieved the detection of this polarization, the published map is heavily corrupted by foregrounds.

Future generations of experiments, such as the Planck Surveyor (due for launch in 2009), will have to grapple with the thorny issue of foreground subtraction if substantial progress is to be made. But there is a crucial target that justifies these endeavours. Inflation does not just produce acoustic waves, it also generates different modes of fluctuation, called gravitational waves, that involve twisting deformations of space-time. Inflationary models connect the properties of acoustic and gravitational fluctuations so if the latter can be detected the implications for the theory are profound. Gravitational waves produce very particular form of polarization pattern (called the B-mode) which can’t be generated by acoustic waves so this seems a promising way to test inflation. Unfortunately the B-mode signal is very weak and the experience of WMAP suggests it might be swamped by foregrounds. But it is definitely worth a go, because it would add considerably to the evidence in favour of inflation as an element of physical reality

Besides providing strong evidence for the concordance cosmology, the WMAP satellite has also furnished some tantalizing evidence that there may be something missing. Not all the properties of the microwave sky seem consistent with the model. For example, the temperature pattern should be structureless, mirroring the random Gaussian fluctuations of the primordial density perturbations. In reality the data contains tentative evidence of strange alignments, such as the so-called “Axis of Evil” discovered by Kate Land and Joao Magueijo. These anomalies could be systematic errors in the data, or perhaps residual problems with the foreground that have to be subtracted, but they could also indicate the presence of things that can’t be described within the standard model. Cosmology is now a mature and (perhaps) respectable science: the coming together of theory and observation in the standard concordance model is a great advance in our understanding of the Universe and how it works. But it should be remembered that there are still many gaps in our knowledge. We don’t know the form of the dark matter. We don’t have any real understanding of dark energy.  We don’t know for sure if inflation happened and we are certainly a long way from being able to identify the inflaton. In a way we are as confused as we ever were about how the Universe began. But now, perhaps, we are confused on a higher level and for better reasons…

Advertisements

29 Responses to “Who put the Bang in Big Bang?”

  1. Anton Garrett Says:

    Peter,

    I think you needn’t write so defensively about speculative stuff; all that is necessary is to distinguish clearly when you are speculating and when you are asserting. These lines of work are driven principally by observations which stem from advances in detector technology; that is healthy science.

    Personally I await a deeper theory from which flatness emerges as naturally as did spin-1/2 from the Dirac equation, rather than having to be put in by hand. If this comes, it will emerge under the stimulus of data which provide more of the picture. A good start might be the Cambridge Gauge Theory of Gravity (GTG), which is first-order differential with respect to quantities equivalent to the metric of General Relativity (GR). In contrast, GR is second order with respect to the metric. The reduced freedom in GTG is not enough to enforce flatness, but is a step in the right direction.

    Anton

  2. A very well written, very informative article, heads above others of a similar ilk.

    I believe it will eventually be realized that both the Big Bang model and General Relativity are incorrect theory. That’s why Inflation is needed, dark matter, dark energy, concordance cosmology, etc. The answer I believe is profoundly simpler.

    see pantheory.org

  3. I.
    Excerpt from “The Yoga of Physics” by Fritjof Capra, his keynote address at the Los Angels symposium on Physics and Metaphysics, on October 29, 1977 is given below for reference.

    “What is the nature and origin of the universe? what is space? what is time? Throughout the ages men and women have been fascinated by these questions. Different approaches have been developed in different cultural contexts and at different times.”

    “We shall look at modern Western science, on the one hand , and Eastern mysticism – particularly the tradition of Yoga – on the other. We shall see that they lead to very similar views of the world.”

    “My field is Physics, a science which, in the 20th century, has led to a radical revision of many of our basic concepts of reality.”

    “In the Yoga tradition it is said that there are many paths, all leading to spiritual knowledge and Self-Realization. I believe that modern physics, to some extent, can be such a path. Its view of the universe is in harmony with those of the great yogis and sages. In that sense, I’m going to talk of the Yoga of Physics.”

    II.
    Many views on the Origin of Universe are available. Most popular view is that universe was born with a big-bang from a highgly dense energy point. But I have some different view on it. I think the universe was not born from a concentrated point or ball like structure but it has evolved from an infinite vast expanse of field of gravity. Philosophically or religously we may call it field of consciousness or spirituality.

    A great flow of current of gravitation force descended down from this source and has created many regions of pure gravitation force below it. This was the creation for quite some time in the first phase of the creational process. In the second phase when the current of gravitation force further descended down then electromagnetic forces and matter (weak and strong nuclear forces)manifested and the entire universe of the second phase was completed with the admixture of all the forces viz., gravitatin force, electromagnetic forces, and matter (weak and strong nuclear forces. The completion of the whole cosmos in two phases was also hinted in one of the speeches of Prof. J.V.Narlikar some years back. When the process of creation of universe reverts back in Brahmand (universe created during second phase of creational process)the matter merges into electromagnetic force and then finally electromagnetic forces merge into gravitation force and nothing remains except field of gravity in a highly dense body (Black Hole. The process of reversal does not take place in the universe created during first phase of creation. The cycle of universe completes like this.

    Many philosophical-scientific evidences and theologians views can be quoted in support of this assumption

  4. Anton Garrett Says:

    Dear A K Satsangi

    Define “consciousness” in physical terms and you will have made a statement. As yet one of your key concepts is undefined, so that your statement is incomplete and cannot be discussed.

    Physical cosmology aims to extrapolate backwards in time, using equations of time evolution (which we currently take from our best theory, general relativity) and observational data. This procedure leads us to a singularity in spacetime, a finite length of time ago. The unfolding forwards in time of the universe from that singularity is what we believe to be the actual history of our universe. The first fleeting moments of that expansion are the ‘Big Bang’. Unless the singularity is mitigated by quantum effects, or unless general relativity breaks down at such extremes, this is unavoidable. Neither of these possibilities is certain. The Big Bang is a best bet.

    Cosmology is part of physics, which is part of science, which emerged in Western culture, which was informed by the Judaeo-Christian worldview. It is not true to say that cosmology meshes well with eastern worldviews. In particualr, the Old Testament says that one god created all that is not him, so that the universe had a beginning. That agrees with science. The eastern view is that all is cyclical, and therefore disagrees with science.

  5. a.k.satsangi,

    I perused the book The Tau of Physics maybe 10 years ago and agree that quantum theory has similarities to Eastern philosophies. In my related theories both ideas/ philosophies are a type of mystical nonsense. Quantum mechanics, on the other hand, is a sum of a number of very useful mathematical models and a history of observations which are invaluable for quantum analyses but collectively provide little or no insight into the workings of reality at any level, contrary to the beliefs of its practitioners.

    Your theories seem rather mystical but interesting. I think you need to write them down in detail and do the research to check them against observation. If they cannot eventually be tested in some way by observation, they are in the same category as Inflation theory, seemingly forever unknowable

    Anton Garrett,

    “The first fleeting moments of that expansion are the ‘Big Bang’” should have been qualified by writing “the first fleeting moments of expansion are currently believed to have been caused by a Big Bang and a subsequent Inflation of the cosmos”. I think you will find that for the reasons that I presented above, the Big Bang model will not be with us for more than a decade or two longer at which time it will be completely be replaced.

    see predictions page 104 of pantheory.org. as well as the technical paper indicated in the header.

    General Relativity broke down in 1974 when it became apparent by the discoveries of Vera Rubin that either General Relativity was completely wrong at stellar distances, or that a kind of unseen “dark” matter must dominate the halo of a galaxy by 99%, or roughly 90% the mass of the entire galaxy. The inner galaxy must contain little of it in diminishing concentrations inward, similar logic to the epicycles theorized by Ptolemy.

    I agree that the universe had a beginning, but I believe that in not too long a period of time you will realize that this beginning of the universe was vastly simpler than a Big Bang and Inflation theory.

    Your writings and understanding of present day cosmology is seemingly very good. Enjoyed reading your comments as well as the author’s.

  6. Anton Garrett Says:

    Dear Forrest Noble

    Please give me a self-contained summary of why you believe General Relativity is wrong.

    Best
    Anton Garrett

  7. Dear Anton Garrett

    Thanks for your querries. What I strongly believe is:

    Current of consciousness = gravitational wave

    mind force = electromagnetic force

    body (physical force) = weak and strong nuclear force

    Wish you, dear Forrest Noble and all a very very Happy New Year

  8. Anton Garrett Says:

    Dear AK Satsangi

    Please develop your beliefs about consciousness to the point that they make testable physical prediction; then we can discuss them as science, which is what you are presenting them as.

    Best
    Anton Garrett

  9. Many things are common between Current of Consciousness and Gravitational Wave.
    1. Current of consciousness can not be seen by any means and gravitational wave can also not be seen.
    2. Current of consciousness is the weakest force on earth. Its strength goes on increasing on higher regions. Gravitational force is also very weak on earth and strong on Sun and even more stronger on black holes.
    3 Tendency of both current of consciousness and gravitational waves are towards their source or centre.
    4. Current of consciousness and gravitational force are both regarded as the creater of all the celestial and terrestrial bodies of the whole universe. They are also sustainer of these and when they turn back towards their source or centre the whole universe collapse.
    5. Action of both consciousness and gravitational wave is inward. Whereas the action of mind and electromagnetic wave is outward. Mind functions through sensory organs with the help of electromagnetic waves.

  10. telescoper Says:

    Sigh.

  11. Mr. Garrett,

    i.e. self contained, brief explanation why General Relativity is completely wrong at stellar distances within a galaxy:

    Since Vera Rubin discovered the actual motion of stars within a spiral galaxy, it was realized that General Relativity or Newtonian gravity formulations did not apply in the slightest way to the stellar motions actually observed. The same realization became apparent concerning orbital motions of galaxies within a cluster. Because of this complete (not even close) failing of prediction, dark matter was invented.

    The problem with the dark matter model is that each observed galaxy would have to contain different distributions of dark matter, something like the system of Ptolemy’s epicycles, therefore there would be no way to ever make any predictions at all using General Relativity excepting for orbital motions at very close distances. For this reason new formulations were developed to enable the prediction of this motion.

    The first of these models was called MOND gravity. A group of new additional formulations are called TeVeS gravity. My own formulations are based upon a non-linear vortex current model of gravity which can be seen at pantheory.org — pages 57D through 57E. Dozens of other new theoretical formulations exist to totally replace General Relativity, especially the cosmological model that can’t predict anything actually observed.

    Mr. Sansangi,

    Consciousness is based upon electrochemical communications/ signals between neural brain cells and other neural cells of the central nervous system. Gravity, on the other hand, regardless of the theory, results in the motion of matter toward other matter. They is no relationship between the two. Reality, as well as the entire universe, is based upon presently unknown simple principles that I believe will eventually be taught in Junior High School. Such teachings, I profess, will be based upon the idea that: If it’s not very simple to the average person, scientifically verifiable, and completely logical then it’s probably wrong.

  12. telescoper Says:

    Dear Mr Forrest Noble,

    Stellar motions within galaxies are perfectly well explained using Newtonian gravity. The only strong evidence for dark matter is supplied by the motion of matter in the outskirts of the galaxies where stars themselves are rare and kinematical evidence is supplied by diffuse gas. I suggest you read some of the more recent scientific results in this area (i.e. later than the 1970s) before making such dogmatic assertions as that GR does not apply “in the slightest way” to stellar motions.

    It seems to me quite reasonable to infer the presence of dark matter to explain these motions as there is plenty of independent evidence for the existence of material that cannot be seen. Only a tiny fraction of matter exists in the form of luminous stars. And galaxies contain different distributions of stellar material anyway so why should they not contain different distributions of dark matter?

    And if we are going to quibble about testability, I’d like to ask for you to provide a testable prediction of your so-called vortex theory. I was unable to find a single one in your rambling and incoherent online dissertation.

    I don’t deny the possibility that General Relativity might be wrong, but I don’t think galactic dynamics provides evidence of such a failing. It is in the strong field regime where discrepancies are more likely to be found.

    Peter

    PS. by the way, please address my friend Anton as Dr Garrett.

  13. telescope,

    Only a galaxy’s core stars seem to follow Newtonian gravity. Disk stars do not. As I said before, the problem with the dark matter concept, as it is presently presented, is that dark matter density must be non-uniform and of no discernible pattern. This does not deny the existence of dark matter, only the present model of it that attempts to explain the failings of Newtonian gravity. My own theory at pantheory.org uses a particle Aether theory to explain gravity as a pushing force, different from other pushing gravity models. This aether field could also be called dark matter.

    The test of the existence of aether would be a MM type experiment concerning the speed of light. Accordingly Aether surrounds all matter. Matter does not move through the Aether. It is stationary relative to matter. Instead it moves into matter because all matter creates waves and emanates EM radiation outward. These density waves are radiated away from matter creating a relatively low pressure area in the field surrounding all matter, hence the vortex model of field material moving steadily into these low pressure areas. The speed of light up vs. down (on the Earth’s surface) would accordingly have a difference of 64 ft. per second, or twice the acceleration rate of gravity. MM could not detect such a small difference and there equipment also could not be used to check up vs. down because of angular friction. A modern evaluation at let’s say a 30 degree angle over a substantial distance would probably be able to detect this speed difference if it exists. Such an experiment could probably be done today using off-the-shelf lasers and precision timers, for less than 500 thousand pounds providing special equipment does not have to be designed.

    If gravity does not work according to the standard model(s) then current estimates concerning the relative quantity of dark matter would not apply — although my own formulations also indicate that most of the matter within the universe is non-baryonic and “dark matter” is as good a name as any.

    The complete details of how all of reality is proposed to work according to these theories can be seen at pantheory.org

    • telescoper Says:

      Only a galaxy’s core stars seem to follow Newtonian gravity. Disk stars do not.

      Please cite some evidence for this assertion.

  14. Hey telescoper:

    My quote: Only a galaxy’s core stars seem to follow Newtonian gravity. disk stars do not.

    Your request: “Please cite some evidence for this assertion.”

    There are a number of sources but I think I like this one best.

    http://en.wikipedia.org/wiki/Galaxy_rotation_curve

    • telescoper Says:

      Wikipedia is hardly an authoritative source and the article you refer to has many inadequacies. It fails to point out, for example, that the “predicted” rotation curve shown in Figure 1 assumes that the material is spherically distributed, which it is not if it is confined to a disk. Modelling a galaxy’s disk is quite difficult, and that no doubt contributes to the task of finding dynamical evidence for a dark component.

      However, more recent observations have demonstrated that there is no need to invoke dark matter (or anything else) to explain stellar motions in the solar neighbourhood. For example, based on Hipparcos observations of the motions of stars in the disk of the Milky Way which are perfectly well explained by Newtonian gravity, (e.g. Creze et al. 1998, A&A, 329, 920-936) decided that there is no evidence for dark matter in the disk of the Milky Way.

      The evidence for dark matter in a galaxy’s halo comes from motions observed much further out than this, as is clear from the quotation from Vera Rubin’s 1980 paper:

      Observations of a set of spiral galaxies gave convincing evidence that orbital velocities of stars in galaxies were unexpectedly high at large distances from the nucleus.

  15. Not at all dear forrest noble. What I mean for Consciousness is given in the following pasages:

    From Scriptures:

    The Current which manifested in the beginning of the creation is the Current of Sabda (Sound) and of Chaitanya (Consciousness). From whom that Current issued forth is known as Soami (Supreme Being). This Current, by turning back can merge again in the Holy Feet of Supreme Being. The entire creation manifested from this current and is sustained with its energy and when the Current of the Holy Feet is withdrawn, the creation ceases to exist.This Current of the Holy Feet is the Reservoir of all energy, tastes and pleasures, knowledge, skill, shapes, forces and light etc. etc. and of the entire creation, is also the Creator of all of them.

    From Science:

    Gravitation Force is the cause of manifestation of the creation (birth of planets, stars), its sustenance and when it is withdrawn towards centre or source the entire creation ceases to exist. Photons have originated from gravitons. In black holes photons merge into gravitons. In Black Holes, Gravitational Force is so high that it does not allow even light to escape. What does it mean then? It simply means that the gravitational force at black-holes attracts light towards it with much greater velocity than the speed of light. In fact, all forces including electromagnetic force, material force (strong and weak nuclear force) all merge into gravitational force in black-holes and becomes one force there and when the creational process starts again from a Black-Hole all the forces appear (manifest) again and descends downwards to create billions of stars, planets, satellite, asteroids and various life forms.

    Hence it can be assumed that the Current of Chaitanya (Consciousness) and Gravitational Wave are the two names of the same Supreme Essence (Seed) which has brought forth the entire creation.

    What I mean for Consciousness is Life Force and what you mean for consciousness is Life Process only.

  16. Telescoper,

    Here’s another link.

    http://cosmology.berkeley.edu/Education/Essays/galrotcurve.html

    There’s a whole list of em. Just search “galaxy rotation curves.”

  17. telescoper Says:

    I don’t need any more links, thank you. I’m an astrophysicist, in case you hadn’t realised. But if you actually read the text at the link you just posted you will accept that it also agrees with what I said, i.e.

    The first real surprise in the study of dark matter lay in the outermost parts of galaxies, known as galaxy halos. Here there is negligible luminosity, yet there are occasional orbiting gas clouds which allow one to measure rotation speeds and distances. The rotation speed is found not to decrease with increasing distance from the galactic center, implying that the mass distribution of the galaxy cannot be concentrated, like the light distribution.

    There is nothing in this to support your assertion that general relativity does not apply to stars in galactic disks.

    This correspondence is now closed.

  18. Hi Telescoper,

    I wanted to thank you for posting your excellent account of Inflation and related cosmological topics. As an experimental high energy physicist, I am not qualified to comment on the basic theoretical ideas. However, I am qualified to praise your superb writing style. You managed to describe these exciting ideas clearly and with almost no jargon at all, yet you did not over-simplify the arguments rendering them trite or superficial. I hope very much you will compose further “Science” posts, and that the odd comments above do not divert you.

    thanks again,
    Michael

  19. […] blogged a few days ago about the idea that the structure we see in this map was produced by sound waves reverberating […]

  20. […] blogged before about the current state of cosmology, but it’s probably a good idea to give a quick reminder. We have a standard cosmological […]

  21. […] as I have blogged about before, newer versions of the Big Bang theory do contain a mechanism for exciting sound waves in the early […]

  22. […] Or does it? Although spatial curvature doesn’t really care about what form of energy causes it, it is surprising to some extent that the dark matter and dark energy densities are similar. To many minds this unexplained coincidence is a blemish on the face of an otherwise rather attractive structure. […]

  23. […] physical theories. The key idea was provided by the theory of cosmic inflation, which I have blogged about already. In the simplest versions of inflation the Universe expands by an enormous factor, perhaps 1060, in […]

  24. […] as I have blogged about before, newer versions of the Big Bang theory do contain a mechanism for generating sound waves in the […]

  25. […] It seems the little poll about cosmic inflation I posted last week with humorous intent has ruffled a few feathers, but at least it gives me the excuse to wheel out an updated and edited version of an old piece I wrote on the subject. […]

  26. […] Or does it? Although spatial curvature doesn’t really care about what form of energy causes it, it is surprising to some extent that the dark matter and dark energy densities are similar. To many minds this unexplained coincidence is a blemish on the face of an otherwise rather attractive structure. […]

  27. […] as I have blogged about before, newer versions of the Big Bang theory do contain a mechanism for generating sound waves in the […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: