Three Decades of Space Telescope Observations Converge on a Precise Value for the Hubble Constant
Science history will record that the search for the expansion rate of the universe was the great Holy Grail of 20th-century cosmology. Without any observational evidence for space expanding, contracting, or standing still, we wouldn’t have a clue as to whether the universe was coming or going. Furthermore, we wouldn’t have any idea about its age either – or in fact, if the universe was eternal.
The first act of this revelation came when, a century ago, American astronomer Edwin Hubble discovered myriad galaxies outside of our home galaxy, the Milky Way. And, the galaxies weren’t standing still. Hubble found that the farther a galaxy is, the faster it appears to be moving away from us. This could be interpreted as the uniform expansion of space. Hubble even said that he studied the galaxies simply as “markers of space.” However, he was never fully convinced of the idea of a uniformly expanding universe. He suspected his measurements might be evidence of something else more oddball going on in the universe.
“You are getting the most precise measure of the expansion rate for the universe from the gold standard of telescopes and cosmic mile markers.” — Nobel Laureate Adam Riess
For decades after Hubble, astronomers have toiled to nail down the expansion rate that would yield a true age for the universe. This required building a string of cosmic distance ladders assembled from sources that astronomers have a reasonable confidence in their intrinsic brightness. The brightest, and therefore farthest detectable milepost markers are Type Ia supernovae.
When the Hubble Space Telescope was launched in 1990 the universe’s expansion rate was so uncertain that its age might only be 8 billion years or as great as 20 billion years.
After 30 years of meticulous work using the Hubble telescope’s extraordinary observing power, numerous teams of astronomers have narrowed the expansion rate to a precision of just over 1%. This can be used to predict that the universe will double in size in 10 billion years.
The measurement is about eight times more precise than Hubble’s expected capability. But it’s become more than just refining a number to cosmologists. In the interim the mystery of dark energy pushing the universe apart was discovered. To compound things even further, the present expansion rate is different than it is expected to be as the universe appeared shortly after the big bang.
You think this would frustrate astronomers, but instead it opens the door to discovering new physics, and confronting unanticipated questions about the underlying workings of the universe. And, finally, reminding us that we have a lot more to learn among the stars.
Hubble Reaches New Milestone in Mystery of Universe’s Expansion Rate
NASA’s Hubble Space Telescope has completed a nearly 30-year marathon by calibrating more than 40 “milepost markers” of space and time to let scientists precisely calculate the expansion rate of the cosmos — a mission with a plot twist.
Pursuit of the universe’s expansion rate began in the 1920s with measurements by astronomers Edwin P. Hubble and Georges Lemaître. In 1998, this led to the discovery of “dark energy,” a mysterious repulsive force accelerating the universe’s expansion. In recent years, thanks to data from Hubble and other telescopes, astronomers found another strange twist: a discrepancy between the expansion rate as measured in the local universe compared to independent observations from right after the big bang, which predict a different expansion value.
The cause of this discrepancy remains a mystery. But Hubble data, encompassing a variety of cosmic objects that serve as distance markers, support the idea that something weird is going on, possibly involving brand new physics.
“You are getting the most precise measure of the expansion rate for the universe from the gold standard of telescopes and cosmic mile markers,” said Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and the Johns Hopkins University in Baltimore, Maryland.
Riess leads a scientific collaboration investigating the universe’s expansion rate called SHOES, which stands for Supernova, H0, for the Equation of State of Dark Energy. “This is what the Hubble Space Telescope was built to do, using the best techniques we know to do it. This is likely Hubble’s magnum opus, because it would take another 30 years of Hubble’s life to even double this sample size,” Riess said.
Riess’s team’s paper, to be published in the Special Focus issue of The Astrophysical Journal reports on completing the biggest and likely last major update on the Hubble constant. The new results more than double the prior sample of cosmic distance markers. His team also reanalyzed all of the prior data, with the whole dataset now including over 1,000 Hubble orbits.
When NASA conceived of a large space telescope in the 1970s, one of the primary justifications for the expense and extraordinary technical effort was to be able to resolve Cepheids, stars that brighten and dim periodically, seen inside our Milky Way and external galaxies. Cepheids have long been the gold standard of cosmic mile markers since their utility was discovered by astronomer Henrietta Swan Leavitt in 1912. To calculate much greater distances, astronomers use exploding stars called Type Ia supernovae.
Combined, these objects built a “cosmic distance ladder” across the universe and are essential to measuring the expansion rate of the universe, called the Hubble constant after Edwin Hubble. That value is critical to estimating the age of the universe and provides a basic test of our understanding of the universe.
Starting right after Hubble’s launch in 1990, the first set of observations of Cepheid stars to refine the Hubble constant was undertaken by two teams: the HST Key Project led by Wendy Freedman, Robert Kennicutt and Jeremy Mould, Marc Aaronson and another by Allan Sandage and collaborators, that used Cepheids as milepost markers to refine the distance measurement to nearby galaxies. By the early 2000s the teams declared “mission accomplished” by reaching an accuracy of 10 percent for the Hubble constant, 72 plus or minus 8 kilometers per second per megaparsec.
In 2005 and again in 2009, the addition of powerful new cameras onboard the Hubble telescope launched “Generation 2” of the Hubble constant research as teams set out to refine the value to an accuracy of just one percent. This was inaugurated by the SHOES program. Several teams of astronomers using Hubble, including SHOES, have converged on a Hubble constant value of 73 plus or minus 1 kilometer per second per megaparsec. While other approaches have been used to investigate the Hubble constant question, different teams have come up with values close to the same number.
The SHOES team includes long-time leaders Dr. Wenlong Yuan of Johns Hopkins University, Dr. Lucas Macri of Texas A&M University, Dr. Stefano Casertano of STScI and Dr. Dan Scolnic of Duke University. The project was designed to bracket the universe by matching the precision of the Hubble constant inferred from studying the cosmic microwave background radiation leftover from the dawn of the universe.
“The Hubble constant is a very special number. It can be used to thread a needle from the past to the present for an end-to-end test of our understanding of the universe. This took a phenomenal amount of detailed work,” said Dr. Licia Verde, a cosmologist at ICREA and the ICC-University of Barcelona, speaking about the SHOES team’s work.
The team measured 42 of the supernova milepost markers with Hubble. Because they are seen exploding at a rate of about one per year, Hubble has, for all practical purposes, logged as many supernovae as possible for measuring the universe’s expansion. Riess said, “We have a complete sample of all the supernovae accessible to the Hubble telescope seen in the last 40 years.” Like the lyrics from the song “Kansas City,” from the Broadway musical Oklahoma, Hubble has “gone about as fur as it c’n go!”
The expansion rate of the universe was predicted to be slower than what Hubble actually sees. By combining the Standard Cosmological Model of the Universe and measurements by the European Space Agency’s Planck mission (which observed the relic cosmic microwave background from 13.8 billion years ago), astronomers predict a lower value for the Hubble constant: 67.5 plus or minus 0.5 kilometers per second per megaparsec, compared to the SHOES team’s estimate of 73.
Given the large Hubble sample size, there is only a one-in-a-million chance astronomers are wrong due to an unlucky draw, said Riess, a common threshold for taking a problem seriously in physics. This finding is untangling what was becoming a nice and tidy picture of the universe’s dynamical evolution. Astronomers are at a loss for an explanation of the disconnect between the expansion rate of the local universe versus the primeval universe, but the answer might involve additional physics of the universe.
Such confounding findings have made life more exciting for cosmologists like Riess. Thirty years ago they started out to measure the Hubble constant to benchmark the universe, but now it has become something even more interesting. “Actually, I don’t care what the expansion value is specifically, but I like to use it to learn about the universe,” Riess added.
NASA’s new Webb Space Telescope will extend on Hubble’s work by showing these cosmic milepost markers at greater distances or sharper resolution than what Hubble can see.
Reference: “A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team” by Adam G. Riess, Wenlong Yuan, Lucas M. Macri, Dan Scolnic, Dillon Brout, Stefano Casertano, David O. Jones, Yukei Murakami, Louise Breuval, Thomas G. Brink, Alexei V. Filippenko, Samantha Hoffmann, Saurabh W. Jha, W. D’arcy Kenworthy, John Mackenty, Benjamin E. Stahl and Weikang Zheng, Accepted, The Astrophysical Journal.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.
“Something weird” with the phase change experiment we call the universe.
LOVE how the newest excuse for “something, something something doesn’t fit our equations” is “dark matter.”
Quote: “we know dark matter is there because stuff happens we can’t explain…”
I remember reading that in the 1700s scientists got together and “decided mathematically” that the top speed a human body can go is 12.5 mph. Any speed higher and the human body would explode from the forces. Check Scientific American for this scientific “fact.”
The ignorance of this response is overwhelming. While the id of precisely what dark matter is (whether it is merely undiscovered or hidden “regular” matter i.e. matter hidden in black holes or otherwise evading our observations, or something more exotic) can still be reasonably argued, denying it outright is absurd. More responsive, however, is that you have confused two distinct issues: the issue related to this piece is not dark matter but dark energy, a hypothesized phenomenon that apparently is totally unrelated to dark matter. Science is always open to adjustments based on facts; that is the very nature of science, but this type of criticism is thinly concealed anti science propaganda.
So. If space between galaxies expands… Is matter what cancels out expansion?
The increasing rate with distance from us being uniform is odd…. Shouldn’t we see the same rate of expansion from any galaxy with space in the middle between galaxies expanding fastest?
So is earth the center of everything expanding outward or is space not actually accelerating in the pattern they say?
Are they using math to explain the movement of the human body outside of the simulation AKA the Dendra light
As a lay discoverer I’ve previously posted on multiple sites including SciTechDaily dot com (recently) that in my model of the universe, contrary to scientific consensus, gravity is locally induced by some still mysterious force in all matter to radiate outward in expanding fields of angular pulsing coiling and spiraling lines of attractive force. Therefore, with photons being small and light enough to be influenced in deep space by individual lines of gravity force, it stands to reason that more distant cosmic objects would appear to be farther away than they actually are. They would tend to accelerate departing their source and decelerate when they cross into our solar/planetary (S/P) field of gravity. Because we can only observe from within the S/P field all we can see is the deceleration, generally misinterpreted as there being a ‘constant speed of light’ from each distant source observed.
As to dark energy and dark matter, as also previously posted in multiple places, gravity lines of force are intensified in rotating objects which, in conjunction with a less expansive universe and the rotation of most of the objects within, probably accounts for those. Previously posted links to a few senior-lone-lay-investigator low budget at-home videos on my newer Odysee dot com video channel were removed or I would post one again. As is, searching “@charlesgshaver” on Odysee might help to locate what are generally interpreted to be videos demonstrating only things like centrifugal force, centripetal force and angular momentum. But, those are only dogmatic old labels which only describe particular actions, not explain them.
Surrounding my rotating wheels I can visualize invisible relatively sparse ‘blades’ of locally induced gravity lines of attractive force pushing/pulling against relatively dense coils of the earth’s ambient field of gravity, akin to boat motor propeller blades when pushing/pulling against bodies of water. Difficult for even me to comprehend, it poses some interesting questions about the big picture. For one, is there a limit to the speed of light (matter?) in deep space? Another is, is there anything to change direction and/or velocity with in deep space? Except for the bio-supercomputer between my ears and my rather fertile imagination, both of those questions are currently a tad beyond my at-home abilities and resources for me to investigate.
So basically you’re saying light may have a completely different speed between galaxies and the local masses cancel out expansion and stuff could be further or closer than they appear.
Thanks for the reply, sorry if I kept you waiting; probably not exactly ‘cancel out.’ Perhaps I explain it better here: https://scitechdaily.com/astronomy-astrophysics-101-measuring-the-age-and-size-of-the-universe/#comment-683791
I think we are too Matter centric. Rather we should approach the Universe from the Dark Energy standpoint. All the Matter is just a minor by-process in a Cosmic sense. Flow of the Dark Energy and its characteristics defines the Universe, and its expansion, but also created the space, which in turn creates the particles, and all the luminous matter, including us.
Does Dark Energy, that dramatically differs from so-called Vacuum or Zero-Point Energy, interact with Dark Matter? Can Dark Matter be such a form of the underlying components of Matter that it can “see” Dark Energy? Is Dark Matter extra-dimensional? Is Dark Energy multidimensional? How would that work? Are higher dimensional components of the universe there?
Are we be tested? Are these the secrets of more advanced civilizations?
Where are the new Einsteins that can figure these things out?
If “string theory” is road apples, where’s the new stuff?
If I correctly, Albert Einstein many years ago told us that “The Universe is not only strange, it is stranger than we can imagine!”
This whole cosmological matter seems to fit with Dr Einstein’s postulate perfectly.
Was this article even reviewed before publishing? In the beginning of the article it states that the expansions was realized when the brighter galaxies being the furthes in the universe? It was do to the amount of red shift in light (change in wavelength and not it’s change in brightness)
What was that an exhibition? Let us put things straight here at least for the microwave background sake.
The first and most serious problem of the origin of the galaxies and universe is the inhomogeneities in a large scale. 2nd. The extreme smoothness of of the microwave background posed or,poses another theoretical problem.
3rd. According to the BB, theory points in the universe seperated by more than the distance light can have traversed sense the universe began (some 10-20 billion of years….. Supposedly), can’t have effect one another. As a result parts of the sky seperated by more than a few degrees would lay beyond each others sphere of influence.
So,how did the microwave background achieved such a uniform temperature?
5th.The question demonstrates one of the most basic parameters of the theory,the number of photons per proton, is wholly arbitrary. And, why there be twelve million photons, per proton, rather 12000 of 36000.
6th.Why is the temperature of the microwave background 2.7 Kelvin rather some other temperature?
7th. The isotropic temperature in the background created as well different problems, and so forth. Not to mention that steady state theory still stands and long with the plasma theory still holds a great degree of ground so definitely speaking big bang it wasn’t the beginning of our universe was apart of clumps in a space that it’s an every time every some Trillion of years takes place through a singular point,(for our universe)!
Not to mention that puzzling fact of anglotarnations of the supermassive stellar clusters that their existence been confirmed for the last 100/150 billions of years prior of thep big bang.
And, some of U geniuses hiding behind yr finger denied the fact, by coming up with even more complicated theories, and mathematical formulas simply being naive ignorant fools,by not accepting on yr paper infinite possibilities, by removing them! The observed universe at this point is only 1% the rest 99%? We blame dark energy and dark matter.
As a brilliant peer of your community put it…. Dark matter dark energy is the little man that isn’t there!
Our belief in expansion is based upon red shift. But, we would not be so quick to accept expansion, but for the big bang. The big bang requires expansion, and the size of the universe as we detect requires instant inflation. There was no big bang, singularity, infinity, expansion, or instant inflation. Red shift is caused by the effects of all the influences of all the other streams of high energy particles and all the celestial objects along the paths of the streams we detect. We resort to exotic, speculative physics, myth and magic, because we do not understand. That’s not very scientific.
Perhaps there is universal time compression over time, such that interpreting observations of red shift only within the framework of relativistic effects under a continuous uniform average time rate is leading to contradictory estimates of the Hubble Constant, dark matter, dark energy, and the age of the universe. Perhaps some of these contradictions would evaporate if universal time compression were considered. I have noticed within my own life an apparent compressing of time as the ratio of “unit time” to time alive gets smaller. Perhaps there is an analogous universal effect, or perhaps time can continuously be compressed forever, like an infinite Shepard Tone, with no beginning and no end. A few thought experiments make it seem to me that universal time compression could address some theoretically problematic observations with respect to the Hubble Constant, dark matter, dark energy, and the age of the universe.
It is not “anti-science” to consider that maybe we don’t know everything some people think we know already. It is “anti-science” to call lay-people with an interest in cosmology “anti-science”. Many actual professional cosmologists think of “dark matter” as a working place-holder to make equations work, and they know observations are just observations, and theory is theory. Both the big bang theory and the dark matter theory are theories, not directly observed phenomena. Hubble himself did not think red shift observations necessarily meant expansion, it just meant red shift observations were made, and so far the best and prevailing theory for those observations is the big bang theory. It may turn out to be wrong, just as other broadly accepted theories have throughout the history of science. I think pop-sci journalism does a disservice to science by conflating established theory with directly observed phenomena. For now the word “theory” should always follow the words “big bang” and “dark matter”. The failure to do so can lead to hubris among physics undergrads, who may then feel they should be rude to anyone with other ideas.
A little clarification added to my post above, perhaps some observations would better fit a model that included universal time compression to some extent, as it would be another contributor to redshift.
Human don’t have precise knowledge of the universe it’s all speculation we don’t poses the brain to figure it out we are minuscule in the universe our knowledge limited to the earth discovery’s we will never know all the facts