New model of cosmic stickiness favors ‘Big Rip’ demise of universe
The universe can be a very sticky place, but just how sticky is a matter of debate.
That is because for decades cosmologists have had trouble reconciling the classic notion of viscosity based on the laws of thermodynamics with Einstein’s general theory of relativity. However, a team from Vanderbilt University has come up with a fundamentally new mathematical formulation of the problem that appears to bridge this long-standing gap.
The new math has some significant implications for the ultimate fate of the universe. It tends to favor one of the more radical scenarios that cosmologists have come up with known as the “Big Rip.” It may also shed new light on the basic nature of dark energy.
The new approach was developed by Assistant Professor of Mathematics Marcelo Disconzi in collaboration with physics professors Thomas Kephart and Robert Scherrer and is described in a paper published earlier this year in the journal Physical Review D.
“Marcelo has come up with a simpler and more elegant formulation that is mathematically sound and obeys all the applicable physical laws,” said Scherrer.
The type of viscosity that has cosmological relevance is different from the familiar “ketchup” form of viscosity, which is called shear viscosity and is a measure of a fluid’s resistance to flowing through small openings like the neck of a ketchup bottle. Instead, cosmological viscosity is a form of bulk viscosity, which is the measure of a fluid’s resistance to expansion or contraction. The reason we don’t often deal with bulk viscosity in everyday life is because most liquids we encounter cannot be compressed or expanded very much.
Disconzi began by tackling the problem of relativistic fluids. Astronomical objects that produce this phenomenon include supernovae (exploding stars) and neutron stars (stars that have been crushed down to the size of planets).
Scientists have had considerable success modeling what happens when ideal fluids – those with no viscosity – are boosted to near-light speeds. But almost all fluids are viscous in nature and, despite decades of effort, no one has managed to come up with a generally accepted way to handle viscous fluids traveling at relativistic velocities. In the past, the models formulated to predict what happens when these more realistic fluids are accelerated to a fraction of the speed of light have been plagued with inconsistencies: the most glaring of which has been predicting certain conditions where these fluids could travel faster than the speed of light.
“This is disastrously wrong,” said Disconzi, “since it is well-proven experimentally that nothing can travel faster than the speed of light.”
These problems inspired the mathematician to re-formulate the equations of relativistic fluid dynamics in a way that does not exhibit the flaw of allowing faster-than-light speeds. He based his approach on one that was advanced in the 1950s by French mathematician André Lichnerowicz.
Next, Disconzi teamed up with Kephart and Scherrer to apply his equations to broader cosmological theory. This produced a number of interesting results, including some potential new insights into the mysterious nature of dark energy.
In the 1990s, the physics community was shocked when astronomical measurements showed that the universe is expanding at an ever-accelerating rate. To explain this unpredicted acceleration, they were forced to hypothesize the existence of an unknown form of repulsive energy that is spread throughout the universe. Because they knew so little about it, they labeled it “dark energy.”
Most dark energy theories to date have not taken cosmic viscosity into account, despite the fact that it has a repulsive effect strikingly similar to that of dark energy. “It is possible, but not very likely, that viscosity could account for all the acceleration that has been attributed to dark energy,” said Disconzi. “It is more likely that a significant fraction of the acceleration could be due to this more prosaic cause. As a result, viscosity may act as an important constraint on the properties of dark energy.”
Another interesting result involves the ultimate fate of the universe. Since the discovery of the universe’s run-away expansion, cosmologists have come up with a number of dramatic scenarios of what it could mean for the future.
One scenario, dubbed the “Big Freeze,” predicts that after 100 trillion years or so the universe will have grown so vast that the supplies of gas will become too thin for stars to form. As a result, existing stars will gradually burn out, leaving only black holes which, in turn, slowly evaporate away as space itself gets colder and colder.
An even more radical scenario is the “Big Rip.” It is predicated on a type of “phantom” dark energy that gets stronger over time. In this case, the expansion rate of the universe becomes so great that in 22 billion years or so material objects begin to fall apart and individual atoms disassemble themselves into unbound elementary particles and radiation.
The key value involved in this scenario is the ratio between dark energy’s pressure and density, what is called its equation of state parameter. If this value drops below -1 then the universe will eventually be pulled apart. Cosmologists have called this the “phantom barrier.” In previous models with viscosity the universe could not evolve beyond this limit.
In the Desconzi-Kephart-Scherrer formulation, however, this barrier does not exist. Instead, it provides a natural way for the equation of state parameter to fall below -1.
“In previous models with viscosity the Big Rip was not possible,” said Scherrer. “In this new model, viscosity actually drives the universe toward this extreme end state.”
According to the scientists, the results of their pen-and-paper analyses of this new formulation for relativistic viscosity are quite promising but a much deeper analysis must be carried out to determine its viability. The only way to do this is to use powerful computers to analyze the complex equations numerically. In this fashion the scientists can make predictions that can be compared with experiment and observation.
###
The research was supported by National Science Foundation grant 1305705 and Department of Energy grant DE-SC0011981.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
I’m sticking with my idea that gravimetric attractive force reverses at some great distance the same way as the nuclear attractive force . It eliminates the need for a dark matter theory IMO but likely impossible to measure the effect, (eg Coulomb’s experiment). Imagine if gravity actually decreased to zero at say 100000(?) light years and reversed beyond that into a repulsive force, would that not explain the acceleration of the universe?
Something like (ignoring relativity for purpose of illustration), F=(1-e^(r-Q))*G*(m1*m2/r^2) where Q is the the critical null distance, where gravitational attraction is zero. The way I constructed this example formula, beyond that distance Q, the flipped repulsive force grows so dramatically with further distance that the universe would be accelerated apart at relativistic speeds not much further away than Q and therefore become unobservable to us. (Kind of like an inverted event horizon of a black hole.)
Personally I like e^-1/x^2 … ( exp (-1/x^2))
It and all its derivatives are zero at x =0.
So it is nowhere and going nowhere, with zero acceleration, and zero rate of increase of acceleration etc….
So how the hell does it ever get to 0.37 at x = 1 ??
Enquiring minds want to know.
Well, George, as I have mused at times, it may be that X=0 is nonphysical — there’s nothing smaller than the Planck distance (granular space-time). If so, some of the infinity problems of General Relativity go away….
Imagine if gravity actually …
===========
modified gravity theories would explain the galaxy rotation problem. why does the outer edge of our galaxy travels much faster than predicted by our current understanding of gravity?
It’s those pesky sub-sized shrunken hydrogen/hydrino atoms postulated (& supposedly proven) by Randell Mills and that we can’t see therefore causing all that dark matter (and maybe dark energy).
Universe to end with the sound of a humongous fart. That stinks.
[Snip. ‘David Socrates’, ‘beckleybud’, and a couple dozen other sockpuppet names. ~mod.]
This sounds like what happened after the Burrito Surprise I had at the local Tacqueria the other day.
Just last week the “Big Bang” caused the universe ring like a crystal glass. Maybe the “Big Rip” is the finale
http://www.usm.edu/news/sites/default/files/articles/photos/2015/June/bigbang_expansionWave_Fig2.jpg
Is the Universe Ringing Like a Crystal Glass? , from the University of Southern Mississippi.
The actual paper (Observation of Discrete Oscillations in a Model-Independent Plot of Cosmological Scale Factor versus Lookback Time and Scalar Field Model) is behind a paywall: H. I. Ringermacher and L. R. Mead 2015 The Astronomical Journal 149 137. doi:10.1088/0004-6256/149/4/137.
Some of the charts are at Ringermacher’s website–linked to by the Southern Miss article.
The invention of dark matter & dark energy reminds me of the engineering school “variable correction factor”(VCF). This is defined as that number that can be added, subtracted, multiplied or divided into your answer to get the answer the professor wanted. In order to make the gravitational equations balance F= G X M1 X M2/R^2 to account for the velocity of stars rotating in a galaxy and the acceleration of the rate of expansion of galaxies, they created a “VCF” comprised of a mass that cannot be detected and an energy that cannot be detected. Unfortunately usage of the VCF seldom got a passing grade in engineering school and we really had to get the equations right.
In climate science they renamed the VCF as “adjustments”. now observations match theory, proving the theory was correct all along.
Dark matter and dark energy were invented to correct for gross errors in the calculated mass of stars. It seems that all of the laws of physics are in effect all of the time – not just those that the are assumed to have bearing on the problem at hand. Stellar mass is presently obtained from binary stars using Kepler’s equations which fail to consider the velocity of individual atoms effect on centrifugal force known as the Eotvos effect. Although the effect is small on earth, on a star, it is huge due to the high velocity of individual atoms at the nearly 30 million Kelvin core temperatures found in a typical star like our sun.
‘
Silly boys, still trying to come up with an answer to things so far beyond human capabilities and understanding. Your answer is in the 66 books of the Bible.
No it isn’t.
My personal heretical speculation is that the Big Bang will be found to have been a black hole exploding (they have to get really enormous to do this – a significant fraction of the mass of the observable universe). Beyond our observable horizon is a universe teeming with enormous black holes embedded in galaxies. Every so often one explodes, annihilating galaxies and creating a local universe.
Everybody’s got to believe in something but I believe it’s too early to have a beer.
Universe destroyed!
Women, minorities hardest hit.
And children?
It all boils down to the acidification of the Universe
Speaking along such lines… could the universe have a net charge?
Did you notice that they didn’t actually mark on the graphic when star formation began? That’s because they don’t really know and there is some pretty good evidence star formation began just 800 million years after the Big Bang which throws some things in the theory out of kilter.
“which throws some things in the theory out of kilter.”
Not mine. The stars formed early because there was debris everywhere.
I just knew it would all end in tears!
Nice one, Harry. A real ripper. Read it yesterday and it didn’t soak in until this morning.
Oh, and AGW will end with a big rip-off! (And tears – the wet sort).
My take on the expanding universe.
Consider the start of the Universe – did it have rotational energy? If it expanded (or inflated) entirely evenly then maybe no. But if there were any areas of greater mass (more galaxies) then inevitably yes.
So the universe is rotating (in the 4th dimension probably, that gives an axis and so a linearity in the dimension of time).
And it’s interacting with the nothing on the edge of the universe. The nothing is “without form and void” but it has potential. So particles must pop in and out of existence just beyond the universe – but without the spin. That stretches the edge of the universe – making an apparently expanding universe.
It’s like a roll of plasticine hanging off the edge of a Gramophone player form the centre of the disk. As the player turns the plasticine stretches and so the universe (measured by the length of the plasticine) seems to expand.
The beauty of this idea is that it explains:
1) The linearity of time
2) Where the energy to expand came from (it’s always been there).
3) What’s outside the universe. It agrees with the standard model about fundamental particles appearing wherever they have potential – even outside the universe.
I really enjoyed the time I spent during the plasticine era. Whole lot of interesting things formed out of nothing in the plasticine era.
But CO2 survives and continues to build up to dangerous levels, threatening any rip survivors.
big rip in 100 trillion years! mark that down in the calendar…..better get working on that bucket list, time is running out.
I’ve always wondered that if the distance between galaxies is new space appearing (the dimes on a balloon model), where does all this new space come from?
So many basic questions to answer about space that it makes us look rather primitive. Answering some of these questions could solve many, if not all, of our energy needs.
Is the paper available and is it on the internet? I would like to read it.
I am hoping someone to will post the End Of the Universe party from “Hitchhikers Guide to the Galaxy” (TV series edition).
Do the Big Rippers have a booth or a mobile at Burning Man ??
I enjoy a thought exercise as much as the next guy, but I just fail to see the benefit of paying highly intelligent people to speculate about such things as “how the universe came to be” and “how the universe will end”. What freakin’ difference does it make? Is it possible that this area of study might produce a bit of practical knowledge which may be useful to the human race within the next 10, 100 or even 1,000 years? I’m sorry if I come across as a curmudgeon, but I’d much rather see this caliber of brain power focused on more practical physics like energy production/transmission, propulsion to/in space, gravity, etc.
Sorry for the rant. I think I need another cup of coffee…
+97
” Is it possible that this area of study might produce a bit of practical knowledge which may be useful to the human race within the next 10, 100 or even 1,000 years?”
Very. Most advances in fundamental science come from playful curiosity which are parlayed into practical applications later, sometimes a LOT later. (e.g. Kepler was never tasked with figuring out how to get to the moon.)
Russell, at the very least this speculation produced the comedy, the Big Bang, ad that is worth something.
A bunch of grad students are running math scenarios and hanging the fate of the universe on the results.
Proof comes in about 22 billion years… maybe.
I’m glad they’re trying new relativistic theories. Only they need to determine provable factors to validate their theory, now, in the present, not eventually.
Big bang; OK, a terrible name for an event mankind is not near clarifying. Still, it is a beginning.
As far as the ever increasing speed of universe’s matter dispersal, I doubt it is a new relativity secret. Watch it be something as simple as matter released into an infinite void of absolute vacuum. The pressure of the universe and all matter continue to push towards filling the infinite void.
But can matter reach a point where matter itself dissolves and evaporates? Not unless those carbon – carbon – oxygen bonds are lot weaker than we think. Perhaps increasing CO2 will help prevent eventual dissolution of the Earth?
Sleep well alarmists, as surely the universe will eventually end and will satisfy even the most rabid alarmist. All ya gotta do is wait… Quietly!
Lol! Be vewy, vewy qwiet!
+1
Robert Frost said it best:
“Some say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.”
Say goodnight Gracie
Goodnight Gracie!
Classic Burns and Gracie!
When I was a teenager, I learned that the periodic table was not filled in as new elements were found. It was filled in with likely elements yet to be discovered. Dmitri Mendeleev, though not the author of the first periodic table done in the form of a cylinder, described the likely properties of missing elements. To describe something unknown (similar to the “missing” forces in the above post) based on mathematical principles, known laws and relationships, is the ultimate in thought experiment. I love it.
When I was 10 I wanted to be an astrophysicist, when I was 14 I wondered how many jobs for astrophysicists there were, I fell into electronics, good career. many years later I realized there would have been plenty of jobs, and I wished I’d got to spend my life with telescopes and trying to understand the Universe.
But this is much, much different than Climate science, astrophysicists are trying to spend trillions in overturning modern society making us use windmills for power for gosh sakes.
But it will be people like the ones writing this paper, studying string theory, studying the Big Bang, smashing elementary particles together at ever increasing energies, who will learn (if it’s possible) to control gravity, learn how to control matter, help us move from relying on chemistry for energy, learn how to fuse hydrogen, bring us the future, if we don’t do this, at some point we will run out of chemical power at least in the amount to run a space age society.
astrophysicists are not trying to spend trillions in overturning modern society
good post
“.. It is predicated on a type of “phantom” dark energy that gets stronger over time.”
Before we even know there is such a thing as dark energy/matter we are now talking about a Lord of the Rings “phantom type”.
I thought it was only climate science and the social sciences (socials went into Marx’s politics a long time ago) that had been ripped by post-normal pathology but, yeah, its the whole works. Lord Kelvin often gets mocked over his view in the late 19 century that there will be only a few loose ends left to discover. He was just a man a few years before his time, there were actually only a half a dozen significant things to discover at the time. Note that these cosmo guys are going to experiment with high powered computers to see if their theory is “viable”. Sound familiar? NCAR and MetOffice and CRU already have the T-shirt. They will get the really powerful one that will make it “viable” and it will be called a discovery. Like Higgs particle – they cooked up a discovery with expensive equipment so that they could report it before Higgs died.
I guess if everything in the here and now has been discovered, it’s not their fault that nothing is left but virtual reality exercises. These seem like the sort of loose ends to be tidied up Lord Kelvin had in mind. I do think there should be at least one guy working on debunking of dark matter/energy and strings, though so that something big about gravity CAN be discovered. Einstein’s gravity recognized Newton’s to be a special case of E’s formula. I’m sure E’s formula will turn out to be a special case of the real one.