Science

Expansion of the universe may not be accelerating after all

Expansion of the universe may ...
A new study casts doubt in the widely accepted view that the universe is expanding at an accelerated rate
A new study casts doubt in the widely accepted view that the universe is expanding at an accelerated rate
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A new study casts doubt in the widely accepted view that the universe is expanding at an accelerated rate
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A new study casts doubt in the widely accepted view that the universe is expanding at an accelerated rate

In 1998, it was discovered that the expansion of the universe is accelerating, a finding that earned three astronomers the Nobel Prize in Physics in 2011, but new research from Oxford University has prompted a rethink of that widely accepted idea. By using a much larger dataset, the team found that the evidence for accelerated expansion doesn't meet the certainty standards required by physicists to declare a discovery.

Type Ia supernovae are often called "standard candles" by astronomers, due to the fact that their peak brightness is consistent and predictable. By measuring how bright that visible light is by the time it reaches Earth, scientists are able to accurately determine how far away the object is. Analyzing these supernovae is what led the researchers in the 1990s to the conclusion that the universe is expanding at an accelerated rate, due to the abundance of "dark" or "vacuum energy."

"The discovery of the accelerating expansion of the universe won the Nobel Prize, the Gruber Cosmology Prize, and the Breakthrough Prize in Fundamental Physics," says Professor Subir Sarkar, lead researcher on the new study. "It led to the widespread acceptance of the idea that the universe is dominated by 'dark energy' that behaves like a cosmological constant – this is now the 'standard model' of cosmology."

In the field of physics, scientists use a scale of "sigma" to determine the certainty of an observation. Before a discovery can be declared, it needs to be shown to reach a level of five sigma, which represents about one chance in 3.5 million that the observation is the result of random fluctuation. Recent discoveries like the Higgs Boson and the detection of gravitational waves both reached a 5-sigma level of certainty.

But when Sarkar's team conducted their own analysis of Type Ia supernovae, they found that the evidence for accelerating universal expansion clocks in at just 3 sigma. Their result incorporates the latest list of 740 objects, which is more than 10 times the amount studied in the original research.

While this finding doesn't necessarily prove that the universe isn't expanding at an accelerated rate, it calls into question deeply-held beliefs that may not stand up to scrutiny. Later studies, including, for example, the cosmic microwave background, which supports the theory of accelerated expansion, may then build on these false assumptions, leading scientists further down the wrong path.

"All of these tests are indirect, carried out in the framework of an assumed model, and the cosmic microwave background is not directly affected by dark energy," explains Sarkar. "It is quite possible that we are being misled and that the apparent manifestation of dark energy is a consequence of analyzing the data in an oversimplified theoretical model – one that was in fact constructed in the 1930s, long before there was any real data."

Revised cosmological models may be able to account for what has been observed without resorting to the mysterious dark energy, which, Sarkar says, "is something of which we have absolutely no understanding in fundamental theory."

The finding may go against the grain of many other studies, including a recent project that suggested the universe is expanding faster than previously thought, but the team hopes the research will help others question assumptions and lead to the development of more airtight models.

"Hopefully this will motivate better analyses of cosmological data, as well as inspiring theorists to investigate more nuanced cosmological models," says Sarkar. "Significant progress will be made when the European Extremely Large Telescope makes observations with an ultrasensitive 'laser comb' to directly measure over a 10 to 15-year period whether the expansion rate is indeed accelerating."

The research was published in the journal Scientific Reports.

Source: University of Oxford

In 1998, it was discovered that the expansion of the universe is accelerating, a finding that earned three astronomers the Nobel Prize in Physics in 2011, but new research from Oxford University has prompted a rethink of that widely accepted idea. By using a much larger dataset, the team found that the evidence for accelerated expansion doesn't meet the certainty standards required by physicists to declare a discovery.

Type Ia supernovae are often called "standard candles" by astronomers, due to the fact that their peak brightness is consistent and predictable. By measuring how bright that visible light is by the time it reaches Earth, scientists are able to accurately determine how far away the object is. Analyzing these supernovae is what led the researchers in the 1990s to the conclusion that the universe is expanding at an accelerated rate, due to the abundance of "dark" or "vacuum energy."

"The discovery of the accelerating expansion of the universe won the Nobel Prize, the Gruber Cosmology Prize, and the Breakthrough Prize in Fundamental Physics," says Professor Subir Sarkar, lead researcher on the new study. "It led to the widespread acceptance of the idea that the universe is dominated by 'dark energy' that behaves like a cosmological constant – this is now the 'standard model' of cosmology."

In the field of physics, scientists use a scale of "sigma" to determine the certainty of an observation. Before a discovery can be declared, it needs to be shown to reach a level of five sigma, which represents about one chance in 3.5 million that the observation is the result of random fluctuation. Recent discoveries like the Higgs Boson and the detection of gravitational waves both reached a 5-sigma level of certainty.

But when Sarkar's team conducted their own analysis of Type Ia supernovae, they found that the evidence for accelerating universal expansion clocks in at just 3 sigma. Their result incorporates the latest list of 740 objects, which is more than 10 times the amount studied in the original research.

While this finding doesn't necessarily prove that the universe isn't expanding at an accelerated rate, it calls into question deeply-held beliefs that may not stand up to scrutiny. Later studies, including, for example, the cosmic microwave background, which supports the theory of accelerated expansion, may then build on these false assumptions, leading scientists further down the wrong path.

"All of these tests are indirect, carried out in the framework of an assumed model, and the cosmic microwave background is not directly affected by dark energy," explains Sarkar. "It is quite possible that we are being misled and that the apparent manifestation of dark energy is a consequence of analyzing the data in an oversimplified theoretical model – one that was in fact constructed in the 1930s, long before there was any real data."

Revised cosmological models may be able to account for what has been observed without resorting to the mysterious dark energy, which, Sarkar says, "is something of which we have absolutely no understanding in fundamental theory."

The finding may go against the grain of many other studies, including a recent project that suggested the universe is expanding faster than previously thought, but the team hopes the research will help others question assumptions and lead to the development of more airtight models.

"Hopefully this will motivate better analyses of cosmological data, as well as inspiring theorists to investigate more nuanced cosmological models," says Sarkar. "Significant progress will be made when the European Extremely Large Telescope makes observations with an ultrasensitive 'laser comb' to directly measure over a 10 to 15-year period whether the expansion rate is indeed accelerating."

The research was published in the journal Scientific Reports.

Source: University of Oxford

19 comments
Nik
The Electric Universe people will be nodding and saying, 'We told you so!'
RaphaelBruckner
Science needs to take a breath...It's only been around for 400 years or so....and Science in its current form thinks it can figure things out that have been going on for millions perhaps billions of years...Well Science (we humans) aren't that intelligent yet....How about we figured a way to save ourselves and the world first..... #therearetomanypeopleonthisplanet
WeeLiam
Wikipedia defines "universe" as "Totality of planets, stars, galaxies, intergalactic space, or all matter or all energy". This is congruent with the meaning I grew up with. So how can the universe be "expanding" at all? What's it expanding into? Itself? How can anything "expand" into itself? It's loose ends such as this that leads people to the notion that cosmologists are all wet.
Douglas Bennett Rogers
The radius of four-space is time. That is what the universe expands into.
Kristianna Thomas
In the cosmic flow of "time", what is a few billion human years? They say that consciousness lags behind the material conditions of society (reality). We think we are the only show in town, and that this is the only universe. Is the universe expanding? In order for us to see if the universe is expanding, we need to see the universe one million years before the Big Bang. Maybe we could see the universe 13.4 billion years before the Big Bang; then we will know for certain if the universe is truly expanding. In order to understand the future; one must understand the past.
LauraFridley
Just a few months short of 22 years ago the original 30 supernovae survey data was published from which all the theorizing about acceleration of the universe and "dark energy" was based. I happened to read that article the data clearly showed for anyone with eyes to see it that it implied accelerated expansion because the discrepancies between the white light measures of distance and those obtained from the red shift measures showed that the discrepancy increased by orders of magnitude based from the least distant to the most. I saw those implications of acceleration but then quickly rejected the idea because (not having the privilege of the invention whole cloth of Dark Energy), the only non-physics violating way such a thing could happen would be if all the matter in the universe were exploding into component radiation, and that would be writ large across the face of the universe for all to see a split before you saw nothing at all ever again because you, too, would have been converted to energy. So now, 20 years after the invention of Dark Energy, I suppose it's time for Perlmutter et al to return their Nobel for "oops, it was a statistical fluke after all." Now, can we all agree to revisit the meaning of the red shift? I've been waiting for 22 years. I'd really like to see that little mystery solved in my lifetime.
Nutsie
I think the conclusion of this paper (written as an exercise by the 'Class for Physics of the Royal Swedish Academy of Sciences') explains the great difficulties involved in this area of discovery: 'What is the source of the dark energy that drives the accelerating expansion of the Universe? Or is our understanding of gravity as described by general relativity insufficient? Or was Einstein’s “mistake” of introducing the cosmological constant one more stroke of his genius?' Scientific theory has it that the Universe was created everywhere in 'the blink of an eye' 13.72 billion years ago and that the Universe is infinite. Then 9 billion years later our solar system appeared and shortly after Earth was formed (4.6 bya) and then miraculously the singularity called 'life' appeared on Earth 3.8 bya. The Universe is out there because we can observe and calculate it, but the tools we use to do this are the sensory tools that humanity has at hand and unless you have the ability to understand infinity then your perception of reality is flawed and there must then be an answer alternative to scientific thought - something with more metaphysical connotations. I am an astrologer and it took me 7 years to get my Diploma because it's a complex science based on thousands of years of observing the heavens. In its observations and correlations with human behaviour it acts as a language of God and its current day abuse is a hugely negative blind spot for understanding Universal origins. Fortunately the children born during the 1990's and the early 2000's have Uranus and Neptune together in their birth charts and the importance of this conjunction and its general inclination is indicated in the Solar Fire program that a lot of astrologers use: 'Your generation will bring about changes in the perception of the places of science and spirituality in society. There may be a merging of the two.' We need science but we also need to understand that we are creation and anything that hurts any part of us will hurt the whole.
JoeSTERN
We assume that the speed of light in a vacuum is constant, but what if it isn't? Let's say it slows down 1% every billion years. After 3 billion years it is only going 97.3% of "the speed of light". After 10 billion years it is only going 90.44% of its original speed. If you examine the red shift in the light of stars at those distances you would conclude that the more distant one is moving away faster so the universe must be expanding.
katgod
Occam will be happy to hear his razor is still useful.
SteveCastleberry
We live on the skin of a planet whose gravity influences our rate of time. Researchers have demonstrated one of Einstein's theories of relativity - that the further away from the Earths center of gravity you are, the faster time passes. Einstein was proven correct when two synchronized atomic clocks were placed on different floors of a tall building. After a year, the clock further from the Earth`s center of gravity gained time quicker. By moving about 10 feet to the top of the stairs, you would age sooner by just under a millionth of a second! ...Also, we live here on Earth in a "changing" rate of time, due to moving bodies of mass around us. Along with lifting the oceans twice a day, our Sun & Moon, as they change distance from the observer, influence the rate of time (however small) for the reader sitting in his chair at his altitude on Earth. Now, let`s step-up this scenario to a scale of about 4.3 million to 1 ... There is a newly discovered super massive black hole at the center of our Milky Way galaxy called Sagittarius A*. All elliptical galaxies are considered to have one. It`s said to contain 4.3 million solar masses & influences all the stars orbiting it in our galaxy. A study in 2008 which linked radio telescopes in Hawaii, Arizona and California (Very Long Baseline Interferometry) measured the diameter of Sagittarius A* to be 27 million miles. For comparison, the radius of Earth's orbit around the Sun is about 93 million miles. Our star, the Sun, is on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm of the Milky Way. Since there are no known perfectly round orbits in the universe, we are either falling into or receding away from the singularity at the center. I maintain that we, along with our sun are being flung out from the singularity along on the Orion Arm . Looking at the picture of a barred spiral galaxy, it`s spiral -shaped for a reason. It`s barred center is spinning & throwing out two jets of stars & dust. Our distance to Sagittarious A* is CONSTANTLY lengthening, which in turn CONSTANTLY changes our rate of time and (from our perspective) everything outside our galaxy LOOKS to speed away from us faster & faster seeming to break Newtons First Law of Motion. I can believe all visible galaxies are essentially expanding away from each other, but accelerating faster? ... & faster? ... No way. I admit, my tiny primate brain may not be able to fathom the total mass of the visible universe & beyond, I mean, -that`s a hell of a lot of mass in motion- but to accept it as mysteriously accelerating faster & faster makes no sense. I would much rather expound a theory that we are not so much traveling IN a bubble of space/time, but rather wherever our location is in distance to bubbles of space/time around these five bodies gives us our rate of time: dM(Earth) + dM(Moon) + dM(Sun) + dM(SagittariusA*) + dM(Big Bang) = Rate Of Time for observer d = distance from mass to observer M = mass I added "The Big Bang" ( whatever that was... ) because space is getting less dense (another variable). The relationship of distance from the observer to these five space/time bubbles, sets the rate of time for the observer, which varies. But an observer would never know it... I believe Saul Perlmutter reported what his instruments sensed but failed to account for the observer`s constant change in distance to a super massive object. This gave him the readings he had of such impossible & illogical accelerations of distant galaxies. Of course our massive singularity was unknown at the time. It goes to show that we`ve got a lot to learn about black holes, about time, and about space. So I don`t expect anyone to find out what Dark Energy is now, because I think it was just convenient at the time to have a label for an unknown "Power", which it wasn`t ... just a slight miscalculation due to the changing distance of an unknown super massive body.