The mystery of the Hubble constant
FECYT – Spanish Foundation for Science and Technology
Solving the discordant data on the expansion rate of the universe is like trying to thread a ‘cosmic needle’, where its hole is the H0 value measured today and the thread is brought by the model from the furthest Universe we can observe: the cosmic microwave background.
Credit: NASA/JPL-Caltetch/ESA-Planck Collaboration/SINC
Physicists use two types of measurements to calculate the expansion rate of the universe, but their results do not coincide, which may make it necessary to touch up the cosmological model. “It’s like trying to thread a cosmic needle,” explains researcher Licia Verde of the University of Barcelona, co-author of an article on the implications of this problem.
More than a hundred scientists met this summer at the Kavli Institute for Theoretical Physics at the University of California (USA) to try to clarify what is happening with the discordant data on the expansion rate of the universe, an issue that affects the very origin, evolution and fate of our cosmos. Their conclusions have been published in Nature Astronomy journal.
“The problem lies in the Hubble constant (H0), a parameter which value -it is actually not a constant because it changes with time- indicates how fast the Universe is currently expanding,” points out cosmologist Licia Verde, an ICREA researcher at the Institute of Cosmos Sciences of the University of Barcelona (ICC-UB) and the main author of the article.
“There are different ways of measuring this quantity,” she explains, “but they can be divided into two major classes: those relying on the Late Universe (the closest to us in space and time) and those based on the Early Universe, and they do not give exactly the same result.”
A classic example of measurements in the late universe are those provided by the regular pulsations of cepheid stars, which the astronomer Henrietta Swan Leavitt already observed a century ago and which helped Edwin Hubble calculate distances between galaxies and prove in 1929 that the Universe is expanding.
The current analysis of the variable brightness of cepheids with space telescopes such as the Hubble, along with other direct observations of objects in our cosmic environment and more distant supernovae, indicate that the H0 value is approximately 73.9 kilometres per second per megaparsec (an astronomical unit equivalent to about 3.26 million light years).
However, measurements based on the early Universe provide an average H0 value of 67.4 km/s/Mpc. These other records, obtained with data from the European Space Agency’s Planck Satellite and other instruments, are obtained indirectly on the basis of the success of the standard cosmological model (Lambda-CDM model), which proposes a Universe made up of 5 % atoms or ordinary matter, 27 % dark matter (made up of particles, as yet detected, that provide additional gravitational attraction so that galaxies can form and clusters of galaxies are held together) and 68 % dark energy, which is responsible for accelerating the expansion of the Universe.
“In particular, these measurements of the primordial Universe focus on the farthest light that can be observed: the cosmic microwave background, produced when the Universe was only 380,000 years old, in the so-called recombination era (where protons recombined with electrons to form atoms),” says Licia Verde.
The researcher highlights a relevant fact: “There are very different and independent ways (with totally different instruments and scientific tools) to measure the H0 on the basis of the early Universe, and the same goes for the late Universe. What is interesting is that all the measurements of one type are in mutual agreement with one another, at an exquisite precision of 1 or 2 %, as are those of the other type, with the same great precision; but when we compare the measurements of one class with those of the other, the discrepancy arises.”
“It looks like a small difference, only 7%, but it is significant considering that we are talking about precisions of 1 or 2% in the value of the Hubble constant,” as emphasised by Licia Verde, who jokes: “It is like trying to thread a ‘cosmic needle’ where its hole is the H0 value measured today and the thread is brought by the model from the furthest Universe we can observe: the cosmic microwave background.”
In addition, she points out some of the consequences of the discrepancy: “The lower the H0 is, the older the Universe is. Its current age is calculated at about 13.8 billion years considering that the Hubble constant is 67 or 68 km/s/Mpc; but if its value were 74 km/s/Mpc, our universe would be younger: it would be approximately 12.8 billion years old.”
Modifying the model in the early Universe
The authors point out in their study that this anomaly does not seem to depend on the instrument or method used for measuring, or on human equipment or sources. “If there are no errors in the data or measurements, could it be a problem with the model?” the researcher asks.
“After all, the H0 values of the primordial Universe class are based on the standard cosmological model, which is very well established, very successful, but which we can try to change a little to solve the discrepancy,” says the expert. “However, we cannot tamper with the characteristics of the model that work very well”.
If the data continue to confirm the problem, theoretical physicists seem to agree that the most promising route for solving it is to modify the model just before the light observed of the cosmic microwave background was formed, i.e. just before recombination (in which there was already 63 % dark matter, 15 % photons, 10 % neutrinos and 12 % atoms). One of the ideas proposed is that, shortly after the Big Bang, an intense episode of dark energy could have occurred that expanded the Universe faster than previously calculated.
“Although it is still highly speculative, with this fine-tuned model, the H0 value obtained with measurements based on the primordial Universe could coincide with local measurements,” notes Licia Verde, who concludes: “It won’t be easy, but in this way we could thread the cosmic needle without breaking what works well in the model.”
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References:
Licia Verde, Tommaso Treu & Adam G. Riess. “Tensions between the early and late Universe”. Nature Astronomy 3: 891-895, October 2019
Universe is an endless cycle of conversion of mass to energy and vice versa. All energy and therefore forces including the gravity are fundamentally electromagnetic (E=mc^2) due to presence of the speed of light constant.
Having this in mind it can be mathematically shown that the Universe space is constant (no expansion) as shown here
http://www.vukcevic.co.uk/CU.htm
Charles Rotter
“(made up of particles, as yet UNdetected, that provide additional gravitational attraction…” ?
IMHO as one who trained and worked in astrophysics, although not in cosmology itself, things like ‘dark matter’ and ‘dark energy’ will turn out to be the Phlogeston of cosmology. Hypothetical entities which serve the narrative but really are just a metaphor for our profound lack of understanding of fundamental aspects and workings of the universe.
But hey, at least no ‘hide the decline’ in that field of research.
Cosmology is mothers-milk to a growing brain.
Astronomy is meat … … er … … soy and rhubarb protein-shake.
Occam’s Razor: The Universe isn’t expanding, the matter we see is expanding outwards as if from a non-uniform explosion.
The whole functioning definition of “universe” is bullshit. Reality exists far far beyond where we can see, the incoming information is just lost as noise.
Recent convoluted imaginings are becoming less and less likely to be correct as their complexity increases.
Most likely, the universe is constant in total combined energy and mass content and spherical in shape but contains regions of convection where mass either moves away from the centre ( KE is converted to PE) or moves back towards the centre (PE is converted back to KE).
In former regions there is expansion and a red shift but in the latter there is contraction and a blue shift and both combined net out to zero.
We are situated in a region that is moving away from the centre and expanding in the process.
Such expansion appears to be accelerating because the amount of space available increases exponentially as one moves away from the centre. Contraction within regions moving back towards the centre would appear to be decelerating because the amount of space available decreases exponentially as one moves towards the centre.
Any sphere containing matter floating freely within a gravitational field will be bound to develop a convective overturning cycle due to the inevitability of density variations caused by uneven heating in the horizontal plane and the universe as a whole is likely to follow that rule.
It is hubris to imagine that you can accurately describe the universe by way of observations from one spot. Which in themselves rely on a number of assumptions made for convenience. OTOH, it doesn’t really matter much, does it?
“The problem lies in the Hubble constant (H0), a parameter which value -it is actually not a constant because it changes with time- indicates how fast the Universe is currently expanding,” points out cosmologist Licia Verde, an ICREA researcher at the Institute of Cosmos Sciences of the University of Barcelona (ICC-UB) and the main author of the article.
Oh is it?
The universe has always been, it is a steady state — the rate at which time passes varies, giving the ILLUSION of an expanding universe. The rate at which time passes is like the movement of treacle with variable viscosity — thin treacle spiraling out of the center (close to the so called big bang origin), thick treacle at the far edges of the universe. However it is never quite totally homogeneous as aggregations of matter warp and bend the rate at which time passes in it’s local vicinity.
I predict if and when the new telescope is in orbit, that a deep field analysis will see objects that are 20+ billion light years away. And the head scratching will continue.
I recently read a 1950s book by Bronowski discussing the development of scientific theory. The most profound point is that as Einstein proved, there is no such force as gravity. It is the distortion of space-time by mass. Newton’s relatively simple equations produce accurate results, except when large masses are involved.
My current view, take aa analogy of the Universe being a large sheet of latex. At Big Bang ( imagine a lot of marbles)the total mass of the universe was at then centre pulling the latex down. At Big Bang the latex rebounded elastically scattering the marbles. Which then spread out across the sheet. The sheet bouncing up and down but with a general slope.
If this analogy is correct then the Hubble Constant should vary like simple harmonic motion depending where you look.
By accepting it is the curvature of space-time removes the need for dark mass or dark energy.
The Scientific Method: observe & measure.
Apply the mind-set or approach of reasonable skepticism.
Or, in other words, scientific scrutiny.
Now more than ever.
“27% dark matter”
Science has so far shown us that there is no such thing as dark matter. By the well tested laws of physics we can say is as true as can be, dark matter cannot exist.
We’re meant to believe a matter that cannot be detected, exchanges information with the space around it, yet that exchange is undetectable apparently, and this matter is 100% reflective as it absorbs nothing, and yet reflects nothing.
Give me a break. LMAO
We need bigger telescopes.
There are two types of science in my experience. ‘Almost settled science’ and unsettled science. The almost settled science of electromagnetism, optics, electronics, chemistry and more. These are examples of science that can be tested in any lab, with the same results.
The Big Bang Theory is one of those that I put in the unsettled science category. I’m sure it was Feynman that said something along the lines of physics equipping you with a great BS detector, which I mention because of my time in Birmingham’s Physics dept. My initial problem with the Big Bang, which seems to be always overlooked, is the simple fact of an infinite mass, with infinite gravity, expanding in the first place.
My other, is that the whole theory strongly relies on red-shift which, for obvious reasons, is always taken to show recession; galaxies speeding away from us in all directions. I know the tired light theory is or has been shown to be BS, but you only need to invoke a single fudge factor or two to remove it, and we’re back to steady state or eternal evolution. The Big Bang needs a lot more fudge factors, invisible forces and undetectable matter. Feel free to point me to more evidence other than red-shift because I’ve struggled to find any.
With regards to Dark Matter, it’s an inescapable fact that galactic rotation can’t be explained by their observable masses. Is there a reason why no one ever looks at electromagnetism as a possible factor? I’m clueless on this one but from what I know, cosmic rays are said to be 80%+ protons and galaxies are spinning. I’ve read that the overall net galactic polarity cancels out in some way but is that settled?
Spinning galaxies with charged electric particles flying around seems to be ignored and the electric universe theory doesn’t help matters at all. Maybe there’s some truth in their theory but my BS-omitter goes in the red when I look at that one.
“the so-called recombination era (where protons recombined with electrons to form atoms)”
How can electrons and protons combining for the first time be recombining?
Do thoughts, ideas, knowledge, intelligence, have mass and/or energy? If not do they exist? Maybe they just have velocity.
In science the best explanation is accepted only until a better one comes along.
If you can accept something from nothing then accepting dark matter is easy.
Contradicting results often mean something is terribly incorrect in our understanding.
Same goes for climate models not matching well with observed temperatures.
The echoes from the big bang imply an infinite universe which implies that there was no big bang to make echoes. Chew on that a while unless you want to decouple space and time, which some have attempted. The microwave background could be the remnants of some “local” event and not the beginning of an infinite universe.
I think that red shift is simply degradation of light wave caused by interaction with gravitational field. It is very simple, the further light wave starts the more gravitational interactions it undergoes. Each interaction is taking a little bit of light wave energy and moving it toward less energetic red spectrum.
It is very simple, imagine light beam bent around some gravity source, e.g. black hole. It is happening we saw pictures of gravity lensing.
When this happens light beam is bent and loses some of its energy, but on the other side, black hole gains equal amount of energy and moves a little bit perpendicular to light beam.
As result whole gravitational universe moves against this one beam path propelled by energy of this light.
Light beam alone is losing its energy, redshifting.
There is no expansion of universe.
most modern “scientists” have convinced this intelligent layperson that they as a group are utterly dishonest and NOT engaged in science on any level…….claims we “know” so much about the universe are pure BS
I can’t understand the point of this article. Why don’t they just change the data to match the model???
the universe is infinite, we likely have seen less than .001% of it yet “scientists” makes claims they KNOW minute details of things unseen.
If the Universe is expanding, then there must be a centre where the original pea that exploded 13.8 billion years ago must have been located. Might there still be some residual matter there? Round that point in the Universe there must be an empty space all round equivalent to the rate of movement of all matter away from this centre. I wonder where that can be. It must by now be a mightily large empty space. If it does not exist the theory of the Big Bang is clearly faulty. I wonder what marvelous mechanism could create all the known and unknown matter in the Universe from a pea.