“Dark matter is hard to see – that’s what makes it dark matter – so to look for it,
you need to think of something clever that no one has tried before”.
If all of that Dark Matter that we cannot actually see, but that the physicists say is out there, is not really out there, then this will mean that some basic laws of physics and astronomy will need to undergo ‘a seismic re-assessment’.
Brendan Cole has recently written about a new scientific attitude regarding dark matter (http://www.sciencealert.com/physicists-just-debunked-one-of-the-most-promising-dark-matter-candidates):
Physicists just debunked one of the most promising candidates for dark matter
Any progress is good.
27 APR 2016
You probably know that just 15 percent of the known Universe is made up of matter that we can actually see. The majority of the Universe – some 85 percent of it – is made up of dark matter and dark energy – two phenomena that are currently 100 percent unknown to science, despite the best efforts of researchers worldwide.
But now, thanks to a paper authored by over 100 physicists… well, it’s still unknown, but it’s just a little less unknown than it was before, because one of the top candidates for dark matter has pretty much been debunked.
The kind of matter that makes up everything we’ve ever seen in the Universe, from tiny quarks to massive galaxies, is only 15 percent of the matter that’s actually out there. The rest is known enigmatically as dark matter, because we can’t see it and no one knows what it is, but we’re almost positive that it’s out there, unless we have to seriously rethink our understanding of the laws of gravity – the force that governs everything in the known Universe.
There are some scientists out there doing this kind of rethinking, but most agree that dark matter has to be something. They just disagree about what that something actually is. The leading contender is a class of Weakly Interacting Massive Particles, or WIMPs. But there are other possibilities with exciting names like axions, axion-like particles, and supersymmetric particles.
Now, thanks to the Fermi Large Area Telescope, the array of possibilities is starting to thin out.
Axions were first proposed in 1977 to resolve a problem in quantum chromodynamics – the theory of how quarks interact with one another. Later, when they were developing string theory over the next 10 or 20 years, they noticed some particles showing up in it that looked a lot like axions.
Physicists are famously good at naming things, so they called these exciting new particles axion-like particles, or ALPs.
It wasn’t long before they realised that axions and ALPs might also make good candidates for dark matter. When the Big Bang created all of the light and matter in the Universe, it should have also created a whole bunch of axions and ALPs – if they exist. But if they do, these particles probably would’ve congregated right where see evidence of dark matter.
Dark matter is hard to see – that’s what makes it dark matter – so to look for it, you need to think of something clever that no one has tried before. And scientists hadn’t really tried looking at gamma rays, so these researchers looked at gamma rays.
Every once in a while, you’d expect an axion or ALP to run into a bit of regular matter, which should send a gamma ray out into space with a specific energy. These gamma rays would then be visible to modern telescopes like the Fermi Large Area Telescope (LAT).
Different models of ALPs predict different numbers of them in the Universe: some models say that all of the dark matter could be ALPs, others say that they make up only a tiny fraction of it. These different models predict different amounts of gamma rays, so you can use the number and kind of gamma rays observed to test the different models of ALPs.
That’s a bunch of steps, but it’s exactly what a team of 102 scientists has done in a recent paper in Physical Review Letters.
They used six years of LAT data on the galaxy NGC 1275 (another very creative name), and checked to see if the observed gamma rays matched some popular models where ALPs make up about 5 percent of the dark matter in the Universe. If these ALP models were right, that would still leave 80 percent of the mass in the Universe unexplained. But you have to start somewhere with these things.
It looks like we’ll have to start somewhere else. The team simulated galaxies with and without the ALPs and then they checked the results of these simulations against those six years of observations. They found that the ALPs don’t seem to predict the observed gamma rays any better than the model without them.
And in science, if you have two hypotheses that perform equally well, you get rid of the one with more stuff in it. In this case, you get rid of the one with those ALPs.
There’s still a big range of possibilities to explore for LAT and for future gamma-ray telescopes. The most obvious one that the researchers mention is a model where ALPs make up all dark matter, not just 5 percent of it. But testing this model is going to take some time.
So it’s possible that in the next few years, we’ll discover what makes up all of the dark matter in the Universe. Or we’ll discover what doesn’t make it up. Either way, that’s pretty exciting.
[End of quote]
According to US author Robert Sungenis, however, there may a more simple alternative, the return to a non-Copernican cosmological model, a biblical or Geocentric Universe (http://loveforlife.com.au/content/10/03/03/new-evidence-earth-center-universe-dark-energy-or-geocentrism-modern-science-crossr):
Dark Energy or Geocentrism?
Modern Science at a Crossroads
By Robert A. Sungenis, Ph.D.
10th December 2008
The most significant scientific evidence that is challenging Copernican cosmology hails from that gathered by astronomers themselves. In short, they are increasingly confronted with evidence that places Earth in the center of the universe. In a paper written by three astrophysicists from Oxford in 2008 evidence for the centrality of the Earth was the simplest explanation for the practical and mathematical understanding of the universe, far superior to the forced invention of “Dark Energy” to support the Copernican model. ScienceDaily put it in simple terms for the layman:
Dark energy is at the heart of one of the greatest mysteries of modern physics, but it may be nothing more than an illusion, according to physicists at Oxford University. The problem facing astrophysicists is that they have to explain why the universe appears to be expanding at an ever increasing rate. The most popular explanation is that some sort of force is pushing the acceleration of the universe’s expansion. That force is generally attributed to a mysterious dark energy. Although dark energy may seem a bit contrived to some, the Oxford theorists are proposing an even more outrageous alternative. They point out that it’s possible that we simply live in a very special place in the universe – specifically, we’re in a huge void where the density of matter is particularly low. The suggestion flies in the face of the Copernican Principle, which is one of the most useful and widely held tenets in physics. Copernicus was among the first scientists to argue that we’re not in a special place in the universe, and that any theory that suggests that we’re special is most likely wrong. The principle led directly to the replacement of the Earth-centered concept of the solar system with the more elegant sun-centered model. Dark energy may seem like a stretch, but it’s consistent with the venerable Copernican Principle. The proposal that we live in a special place in the universe, on the other hand, is likely to shock many scientists.
With the same vigor as Edwin Hubble, recently deceased astrophysicist, Hermann Bondi, had also tried to stem the tide of geocentric cosmology by stating in his 1952 book, Cosmology (published by Oxford’s rival, Cambridge University Press) “the Earth is not in a central, specially favored position.” Bondi hadn’t proved this view; rather, it was merely a scientific presupposition, a foundation from which to interpret all the data that telescopes were gathering, known simply as the “Cosmological Principle” or what is sometimes called the “Copernican Principle.” There was also a second principle at work, what we might call the “Einsteinian Principle,” that is, that the universe obeyed the Special and General Relativistic equations of Albert Einstein. In this model, the universe has been expanding since the Big Bang 13.5 billion years ago. Based on both the Copernican and Einsteinian principles, a grid to measure the universe’s expansion was invented by three physicists, which became known as the “Friedmann-Walker-Robertson (FRW) metric,” but the expansion is only possible, as Clifton, et al say,
…if a fraction of r is in the form of a smoothly distributed and gravitationally repulsive exotic substance, often referred to as Dark Energy. The existence of such an unusual substance is unexpected, and requires previously unimagined amounts of fine-tuning in order to reproduce the observations. Nonetheless, dark energy has been incorporated into the standard cosmological model, known as LCDM.
Clifton then shows that the tweaking required to get the Dark Energy model working is wholly unnecessary if one simply rejects the first principle of cosmology, the Copernican principle:
An alternative to admitting the existence of dark energy is to review the postulates that necessitate its introduction. In particular, it has been proposed that the SNe observations could be accounted for without dark energy if our local environment were emptier than the surrounding Universe, i.e., if we were to live in a void. This explanation for the apparent acceleration does not invoke any exotic substances, extra dimensions, or modifications to gravity – but it does require a rejection of the Copernican Principle. We would be required to live near the center of a spherically symmetric under-density, on a scale of the same order of magnitude as the observable Universe. Such a situation would have profound consequences for the interpretation of all cosmological observations, and would ultimately mean that we could not infer the properties of the Universe at large from what we observe locally.
Within the standard inflationary cosmological model the probability of large, deep voids occurring is extremely small. However, it can be argued that the center of a large underdensity is the most likely place for observers to find themselves. In this case, finding ourselves in the center of a giant void would violate the Copernican principle, that we are not in a special place…
New Scientist wasted no time in laying out the cosmological and historical implications of this study:
It was the evolutionary theory of its age. A revolutionary hypothesis that undermined the cherished notion that we humans are somehow special, driving a deep wedge between science and religion. The philosopher Giordano Bruno was burned at the stake for espousing it; Galileo Galilei, the most brilliant scientist of his age, was silenced. But Nicolaus Copernicus’s idea that Earth was just one of many planets orbiting the sun – and so occupied no exceptional position in the cosmos – has endured and become a foundation stone of our understanding of the universe. Could it actually be wrong, though? At first glance, that question might seem heretical, or downright silly….And that idea, some cosmologists point out, has not been tested beyond all doubt – yet.
When we add to this the fact that no one has ever found physical evidence of the much needed Dark Energy to make the Copernican/Einsteinian model work, it is clear that current cosmology is merely a desperate attempt to avoid the simplest solution to the data – a geocentric universe. As one commentator put it: “Astronomers will find it hard to settle that troubling sensation in the pit of their stomachs. The truth is that when it comes to swallowing uncomfortable ideas, dark energy may turn out to be a sugar-coated doughnut compared to a rejection of the Copernican principle.” New Scientist shows why even the sugar-coated phase gives astronomers a queasy feeling in their stomachs:
This startling possibility can be accommodated by the standard cosmological equations, but only at a price. That price is introducing dark energy – an unseen energy pervading space that overwhelms gravity and drives an accelerating expansion. Dark Energy is problematic. No one really knows what it is. We can make an educated guess, and use quantum theory to estimate how much of it there might be, but then we overshoot by an astounding factor of 10120. That is grounds enough, says George Ellis…to take a hard look at our assumptions about the universe and our place in it. “If we analyse the supernova data by assuming the Copernican principle is correct and get out something unphysical, I think we should start questioning the Copernican principle…. Whatever our theoretical predilections, they will in the end have to give way to the observational evidence.”
So what would it mean if…the outcome were that the Copernican principle is wrong? It would certainly require a seismic reassessment of what we know about the universe….If the Copernican Principle fails, all that goes that [the Big Bang] goes out the window too….Cosmology would be back at the drawing board. If we are in a void, answering how we came to be in such a privileged spot in the universe would be even trickier.
Actually, it’s not really that “tricky.” As Robert Caldwell of Dartmouth College said in remarking on the crossroads that modern cosmology finds itself: “It would be great if there were someone out there who could look back at us and tell us if we’re in a void.” The truth is, Someone has already told us that the Earth was in a privileged spot, many years ago in a book, oddly enough, called Genesis ….