Are elegant mathematical models of the universe more important than empirical observed modelling of our solar system, galaxies and universe?
It's a beautiful theory: the standard model of cosmology describes the universe using just six parameters. But it is also strange. The model predicts that dark matter and dark energy - two mysterious entities that have never been detected - make up 95% of the universe, leaving only 5% composed of the ordinary matter so essential to our existence.
The dark side of cosmology | phys.org
the idea that fundamental particles are actually tiny bits of vibrating string was taking off, and by the mid-1980s, string theory had lassoed the imaginations of many leading physicists. The idea is simple: just as a vibrating violin string gives rise to different notes, each string's vibration foretells a particle's mass and behavior. The mathematical beauty was irresistible and led to a swell of enthusiasm for string theory as a way to explain not only particles but the universe itself.
Gravity is mathematically relatable to dynamics of subatomic particles | phys.org
It's embarrassing, but astrophysicists are the first to admit it. Our best theoretical model can only explain 5% of the universe. The remaining 95% is famously made up almost entirely of invisible, unknown material dubbed dark energy and dark matter.
Bizarre 'dark fluid' with negative mass could dominate the universe | phys.org
Mathematical universe hypothesis
Our external physical reality is a mathematical structure. That is, the physical universe is not merely described by mathematics, but is mathematics (specifically, a mathematical structure). Mathematical existence equals physical existence, and all structures that exist mathematically exist physically as well. Observers, including humans, are self-aware substructures (SASs). In any mathematical structure complex enough to contain such substructures, they will subjectively perceive themselves as existing in a physically 'real' world.
The theory can be considered a form of Pythagoreanism or Platonism in that it proposes the existence of mathematical entities; a form of mathematical monism in that it denies that anything exists except mathematical objects; and a formal expression of ontic structural realism.
Tegmark claims that the hypothesis has no free parameters and is not observationally ruled out. Thus, he reasons, it is preferred over other theories-of-everything by Occam's Razor. Tegmark also considers augmenting the MUH with a second assumption, the computable universe hypothesis (CUH), which says that the mathematical structure that is our external physical reality is defined by computable functions.
Mathematical universe hypothesis | wikipedia
Dark fluid with negative mass and negative gravity
No matter how physically and logically preposterous a proposed universe construct is, to the man in the street, as long as there are no obvious peer reviewed alternatives, then mathematical scientists will at least not be able to be rule it out.
In an essay for The Conversation, Farnes concedes that the negative mass theory could be incorrect - but also expresses hope that, if it’s borne out by future observations, it could provide a new model for explaining the mysteries of the cosmos.
Despite these efforts, a negative mass cosmology could be wrong, he wrote. The theory seems to provide answers to so many currently open questions that scientists will — quite rightly — be rather suspicious. However, it is often the out-of-the-box ideas that provide answers to longstanding problems. The strong accumulating evidence has now grown to the point that we must consider this unusual possibility.
An Oxford Scientist May Have Solved the Mystery of Dark Matter
You can mathematically propose anything and as long as it is not currently falsifiable, it has to be considered as an alternative framework. The more elegant mathematics it uses to possibly explain things, the more popular it might be with those who live in alternative maths universes.
In this new theory, the negative mass particles are continuously created, so the particles are always replenished as the universe expands, he explained. In this new approach, these continuously - created negative masses seem to be identical to dark energy. By combining negative mass and matter creation, dark matter and dark energy can be unified into one single substance - a dark fluid.
One of the reasons we know dark matter exists is its gravitational influence over galaxies. Observations show galaxies are spinning far faster than they should—so fast they should be torn apart. Dark matter, it appears, is helping to hold them together. To test his theory, Farnes created a 3D computer model of his dark fluid to see if it would hold a galaxy together. And it did. “The new model has been tested using a simulation of the universe within a computer, and seems to naturally generate dark matter halos around 'positive mass' galaxies. This is a direct observational expectation of dark matter, and so seems to indicate that the model has promise. However, there is still much work to be done to test this idea further.
Farnes says are limitations to the research: The current model provides no explanation at all for the particle physics that may make negative masses possible, he said. This is currently half of all known physics that is not being included into my model!
However, he also says the nature of mass is poorly understood in particle physics, so ideas of negative mass could be incorporated to explain other scientific conundrums.
Alex Murphy, Professor of Nuclear & Particle Astrophysics at the U.K.’s University of Edinburgh, who was not involved in the study, said the findings are interesting: “It’s one of many efforts trying to provide answers to deeply troubling issues with our understanding of the contents of the universe,” he told Newsweek. “The key result is that if there is the right amount of negative mass matter in the universe, then one can explain the observed motions and distributions of galaxies that otherwise require dark matter and dark energy to exist. That is quite elegant.”
most of the universe is missing — a ‘dark fluid’ with negative mass could explain why | Newsweek
The creator of the field of cosmology, Albert Einstein, did – along with other scientists including Stephen Hawking – consider negative masses. In fact, in 1918 Einstein even wrote that his theory of general relativity may have to be modified to include them.
Despite these efforts, a negative mass cosmology could be wrong. The theory seems to provide answers to so many currently open questions that scientists will – quite rightly – be rather suspicious. However, it is often the out-of-the-box ideas that provide answers to longstanding problems. The strong accumulating evidence has now grown to the point that we must consider this unusual possibility.
Bizarre ‘dark fluid’ with negative mass could dominate the universe | The Conversation
Non Euclidean space-time
According to Albert Einstein's theory of special relativity, instantaneous action at a distance violates the relativistic upper limit on speed of propagation of information. If one of the interacting objects were to suddenly be displaced from its position, the other object would feel its influence instantaneously, meaning information had been transmitted faster than the speed of light.
One of the conditions that a relativistic theory of gravitation must meet is that gravity is mediated with a speed that does not exceed c, the speed of light in a vacuum. From the previous success of electrodynamics, it was foreseeable that the relativistic theory of gravitation would have to use the concept of a field, or something similar.
This has been achieved by Einstein's theory of general relativity, in which gravitational interaction is mediated by deformation of space-time geometry. Matter warps the geometry of space-time, and these effects are - as with electric and magnetic fields - propagated at the speed of light. Thus, in the presence of matter, space-time becomes non-Euclidean, resolving the apparent conflict between Newton's proof of the conservation of angular momentum and Einstein's theory of special relativity.
Einstein - Action at a distance | wikipedia
Dark Matter Hurricanes
But it just may cause some local spikes in dark matter, which would help researchers hunting dark matter actually find the stuff, the researchers wrote.
That's because all galaxies, but especially dwarf galaxies, are held together by dark matter, physicists believe. So, the galaxy that was torn to shreds birthing the S1 stream likely dumped a bunch of dark matter into the stream's path.
The problem is, no existing dark matter-detection devices have actually worked, in part because they've all been designed based on educated guesses as to what dark matter really is. (Scientists have very good reason to believe dark matter exists but are still guessing about its composition.)
Do Not Fear the Dark Matter Hurricane (The Dark Matter Hurricane Is Good)
Strings of gravity particles
The key insight is that gravity, the force that brings baseballs back to Earth and governs the growth of black holes, is mathematically relatable to the peculiar antics of the subatomic particles that make up all the matter around us.
This revelation allows scientists to use one branch of physics to understand other seemingly unrelated areas of physics. So far, this concept has been applied to topics ranging from why black holes run a temperature to how a butterfly's beating wings can cause a storm on the other side of the world.
Meanwhile, the idea that fundamental particles are actually tiny bits of vibrating string was taking off, and by the mid-1980s, "string theory" had lassoed the imaginations of many leading physicists. The idea is simple: just as a vibrating violin string gives rise to different notes, each string's vibration foretells a particle's mass and behavior. The mathematical beauty was irresistible and led to a swell of enthusiasm for string theory as a way to explain not only particles but the universe itself...
The breakthrough in the late 1990s was that mathematical calculations of the edge, or boundary, of this anti-de Sitter space can be applied to problems involving quantum behaviors of subatomic particles described by a mathematical relationship called conformal field theory (CFT). This relationship provides the link, which Polyakov had glimpsed earlier, between the theory of particles in four space-time dimensions and string theory in five dimensions. The relationship now goes by several names that relate gravity to particles, but most researchers call it the AdS/CFT (pronounced A-D-S-C-F-T) correspondence.
Gravity is mathematically relatable to dynamics of subatomic particles | phys.org
Emergent de Sitter Cosmology
"For 15 years, there have been models in string theory that have been thought to give rise to dark energy. However, these have come in for increasingly harsh criticism, and several researchers are now asserting that none of the models proposed to date are workable.”
In their new paper, published in the journal Physical Review Letters, Dr. Banerjee and co-authors propose a new model with dark energy and our Universe riding on an expanding bubble in an extra dimension.
The whole Universe is accommodated on the edge of this expanding bubble, they said. All existing matter in the Universe corresponds to the ends of strings that extend out into the extra dimension.
We also show that expanding bubbles of this kind can come into existence within the framework of string theory. It is conceivable that there are more bubbles than ours, corresponding to other universes.
Universe May Be Riding on Expanding Bubble in Extra Dimension | Sci News
Motivated by this puzzle, we propose an embedding of positive energy Friedmann-Lemaître-Robertson-Walker cosmology within string theory. Our proposal involves confining 4D gravity on a brane which mediates the decay from a nonsupersymmetric five-dimensional anti–de Sitter false vacuum to a true vacuum.
In this way, it is natural for a 4D observer to experience an effective positive cosmological constant coupled to matter and radiation, avoiding the need for scale separation or a fundamental de Sitter vacuum.
Emergent de Sitter Cosmology from Decaying Anti–de Sitter Space
Supermassive gravitinos and N=8 Supergravity Cosmology
Hermann Nicolai and Krzysztof Meissner have presented a new hypothesis that seeks to explain why only the already known elementary particles occur as basic building blocks of matter in nature - and why, contrary to what was previously thought, no new particles are to be expected in the energy range accessible to current or conceivable future experiments.
In addition, the two researchers postulate the existence of supermassive gravitinos, which could be highly unusual candidates for dark matter. In a second publication, which recently appeared in the journal Physical Review D, they also set out a proposal for how to track these gravitinos down.
In their work, Nicolai and Meissner take up an old idea from the Nobel Prize winner Murray Gell-Mann that is based on the N=8 Supergravity theory. One key element of their proposal is a new type of infinite-dimensional symmetry that is intended to explain the observed spectrum of the known quarks and leptons in three families. "Our hypothesis actually produces no additional particles for ordinary matter that would then need to be argued away because they do not show up in accelerator experiments," says Hermann Nicolai. "By contrast, our hypothesis can in principle explain precisely what we see, in particular the replication of quarks and leptons in three families."
A heavyweight candidate for dark matter