Nature: Measurement of Universe's Expansion Rate Puzzling

[bystander]

Measurement of Universe's Expansion Rate Creates Cosmological Puzzle
Nature News | Davide Castelvecchi | 2016 Apr 11

Discrepancy between observations could point to new physics.

Data from galaxies such as M101, seen here, allow scientists to gauge the speed at which the universe is expanding. [b](X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech)

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The most precise measurement ever made of the current rate of expansion of the Universe has produced a value that appears incompatible with measurements of radiation left over from the Big Bang. If the findings are confirmed by independent techniques, the laws of cosmology might have to be rewritten.

This might even mean that dark energy — the unknown force that is thought to be responsible for the observed acceleration of the expansion of the Universe — has increased in strength since the dawn of time.

“I think that there is something in the standard cosmological model that we don't understand,” says astrophysicist Adam Riess, a physicist at Johns Hopkins University in Baltimore, Maryland, who co-discovered dark energy in 1998 and led the latest study.

Kevork Abazajian, a cosmologist at the University of California, Irvine, who was not involved in the study, says that the results have the potential of “becoming transformational in cosmology”. ...

A 2.4% Determination of the Local Value of the Hubble Constant - Adam G. Riess et al

• arXiv.org > astro-ph > arXiv:1604.01424 > 05 Apr 2016

[Ann]

Wowzers! The current Breaking Science News thread is just incredible!

Davide Castelvecchi wrote in Nature:
Their paper1, which has been submitted to a journal and posted on the arXiv online repository on 6 April, reports that they measured the constant with an uncertainty of 2.4%, down from a previous best result2 of 3.3%. They find the speed of expansion to be about 8% faster than that predicted based on Planck data, says Riess.
...
If the findings are confirmed by independent techniques, the laws of cosmology might have to be rewritten.

Incredible! New physics? Or at least, new cosmology?

Well, the jury is still out, and astronomers may have to look at other kinds of standard candles than supernovas type Ia before they can come to a conclusion:

Another possibility is that standard candles themselves that are not reliable when it comes to precision measurements, says Wendy Freedman, an astronomer at the University of Chicago in Illinois who in 2001 led the first precision measurement of the Hubble constant3. She and her team are working on an alternative method based on a different class of stars.

Go, Wendy!

But in any case, this is just amazing, like watching history being made. Or like seeing the universe undergoing an incredible makeover and taking on amazingly different properties before our eyes.

Ann

[neufer]

Davide Castelvecchi wrote in Nature:
Their paper1, which has been submitted to a journal and posted on the arXiv online repository on 6 April, reports that they measured the constant with an uncertainty of 2.4%, down from a previous best result2 of 3.3%. They find the speed of expansion to be about 8% faster than that predicted based on Planck data, says Riess.
...
If the findings are confirmed by independent techniques, the laws of cosmology might have to be rewritten.

Incredible! New physics? Or at least, new cosmology?

Well, the jury is still out, and astronomers may have to look at other kinds of standard candles than supernovas type Ia before they can come to a conclusion:

Another possibility is that standard candles themselves that are not reliable when it comes to precision measurements, says Wendy Freedman, an astronomer at the University of Chicago in Illinois who in 2001 led the first precision measurement of the Hubble constant3. She and her team are working on an alternative method based on a different class of stars.

[img3="Trust the Planck Hubble constant: H₀~ 67.5"
https://www.cfa.harvard.edu/~dfabricant/huchra/hubble/"]https://www.cfa.harvard.edu/~dfabricant ... ummary.jpg[/img3]

It is so easy to contemplate observational biases that favor finding the brightest distant supernova (etc.) making them actually further away = older universe = lower Hubble constant.

Trust the Planck Hubble constant:
H₀ ~ 67.5 (=> 13.8 Gyr universe).

[bystander]

Hubble Finds Universe May Be Expanding Faster than Expected
ESA Hubble Science Release | 2016 Jun 02

Cosmic Distance Ladder - Credit: NASA, ESA, A. Feild (STScI), A. Riess (STScI/JHU)]

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Click to view full size image 1 or image 2

Cepheids in UGC 9391 - Credit: NASA, ESA, L. Frattare (STScI), A. Riess (STScI/JHU)

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Astronomers have used Hubble to measure the distances to stars in nineteen galaxies more accurately than previously possible. They found that the Universe is currently expanding faster than the rate derived from measurements of the Universe shortly after the Big Bang. If confirmed, this apparent inconsistency may be an important clue to understanding three of the Universe’s most elusive components: dark matter, dark energy and neutrinos.

A team of astronomers, led by Nobel Laureate Adam Riess and using the NASA/ESA Hubble Space Telescope, have discovered that the Universe is expanding between five and nine percent faster than previously calculated. This is in clear discrepancy with the rate predicted from measurements of the infant Universe. ...

One possible explanation for this unexpectedly fast expansion of the Universe is a new type of subatomic particle that may have changed the balance of energy in the early Universe, so called dark radiation.

The team made the discovery by refining the measurement of how fast the Universe is expanding, a value called the Hubble constant, to unprecedented accuracy, reducing the uncertainty to only 2.4 percent [1].

This new measurement presents a puzzle because it does not agree with the expansion rate found by looking at the moments shortly after the Big Bang. Measurements of the afterglow from the Big Bang from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency’s Planck satellite mission yield smaller predictions for the Hubble constant. ...

This refined determination of the Hubble constant was made possible by making precise measurements of the distances to both nearby and faraway galaxies using Hubble [2]. The improved distance measurements were made by streamlining and strengthening the cosmic distance ladder, which astronomers use to measure accurate distances to galaxies. The team compared these measured distances with the expansion of space as measured by the stretching of light from receding galaxies and these two values were then used to calculate the Hubble constant. ...

Hubble Finds Universe Is Expanding Faster than Expected
NASA | STScI | HubbleSite | 2016 Jun 02

Universe Expanding Faster than Expected
University of California, Berkeley | 2016 jun 02

Universe Expanding Faster than Scientists Predicted
Johns Hopkins University | 2016 Jun 02

A 2.4% Determination of the Local Value of the Hubble Constant - Adam G. Riess et al

• arXiv.org > astro-ph > arXiv:1604.01424 > 05 Apr 2016 (v1), 17 May 2016 (v2)

[Evermore]

The APOD explanation includes: "They found that the Universe is currently expanding faster than the rate derived from measurements of the Universe shortly after the Big Bang."

But other sources say the late Hubble measurements indicate the increased expansion is faster than was estimated in 1998 .. "The accelerated expansion was discovered in 1998, when two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team simultaneously obtained results suggesting a totally unexpected acceleration ..." https://en.wikipedia.org/wiki/Accelerat ... e_universe

Perhaps this could use clarification?

[bystander]

The APOD explanation includes:

This is not an APOD.

[neufer]

"They found that the Universe is currently expanding faster than the rate derived from measurements of the Universe shortly after the Big Bang."

But other sources say the late Hubble measurements indicate the increased expansion is faster than was estimated in 1998 .. "The accelerated expansion was discovered in 1998, when two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team simultaneously obtained results suggesting a totally unexpected acceleration ..." https://en.wikipedia.org/wiki/Accelerat ... e_universe

Perhaps this could use clarification?

This is basically just a reconfirmation that the Hubble constant H₀ as calculated by HST (~73.2 kilometers per second per megaparsec) is (and always has been) significantly higher than the Hubble constant as calculated by ESA's Planck satellite (~67.8 kilometers per second per megaparsec). Hence, in the plot below the H₀ slope of the line at Now is 9% steeper (with the beginning of the Universe presumably starting at -12.7 billion years rather than [the Planck satellite value of] -13.7 billion years) according to HST.

Note that the accelerating (dark energy) universe dashed line with Ω_M = 0.3 and Ω_Λ = 0.7 is still the best model based upon the independent High-Z Supernova Search Team measurements. However, if we are to believe both HST & Planck, perhaps a new more sophisticated model is required.

[size=150]13.7 billion year old Universe according to Planck (H[sub]0[/sub]=67.8)[/size]

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<<The age and ultimate fate of the universe can be determined by measuring the Hubble constant today and extrapolating with the observed value of the deceleration parameter, uniquely characterized by values of density parameters (Ω_M for matter and Ω_Λ for dark energy). A "closed universe" with Ω_M > 1 and Ω_Λ = 0 comes to an end in a Big Crunch and is considerably younger than its Hubble age. An "open universe" with Ω_M ≤ 1 and Ω_Λ = 0 expands forever and has an age that is closer to its Hubble age. For the accelerating (dark energy) universe with nonzero Ω_Λ that we inhabit, the age of the universe is coincidentally very close to the Hubble age.>>

[Ann]

Is it at all possible that the strength of dark energy has increased since the universe became transparent circa 300,000 years after the Big Bang? Could it be that the primordial dark energy, which was detected by Planck and which was imprinted on the "echo of the birth cry of the universe", the cosmic microwave background, is different from the dark energy in the nearby universe? HST has looked at the imprint of dark matter on galaxies that are basically our own contemporaries, so that they produce Cepheids and supernovas Type Ia almost 14 billion years after the Big Bang. Could it simply be that dark energy is not only accelerating the universe, but it might just possibly be "accelerating itself", too?

Ann

[Evermore]

The APOD explanation includes:

This is not an APOD.

Right. My apologies.

[Evermore]

Is it at all possible that the strength of dark energy has increased since the universe became transparent circa 300,000 years after the Big Bang? Could it be that the primordial dark energy, which was detected by Planck and which was imprinted on the "echo of the birth cry of the universe", the cosmic microwave background, is different from the dark energy in the nearby universe? HST has looked at the imprint of dark matter on galaxies that are basically our own contemporaries, so that they produce Cepheids and supernovas Type Ia almost 14 billion years after the Big Bang. Could it simply be that dark energy is not only accelerating the universe, but it might just possibly be "accelerating itself", too?

Ann

Something seems to be accelerating it .. and it is possible the increases will reveal a mathematical pattern which will predict a phenomenally earlier date for a (theoretical) Big Rip than cosmologists think possible.

[neufer]

Could it simply be that dark energy is not only accelerating the universe, but it might just possibly be "accelerating itself", too?

The traditional big bang cannot expand our local group of galaxies since they are gravitational bound.

Traditional dark energy also cannot expand our local group of galaxies since its density holds constant while our local group remains the same size (see above) so the total local group dark energy remains constant.

However,

• 1) the dark energy density possibly could increase (leading to The Big Rip);
  2) or some sort of relativistic dark matter "radiation" could decrease (by redshift).

[Ann]

Could it simply be that dark energy is not only accelerating the universe, but it might just possibly be "accelerating itself", too?

The traditional big bang cannot expand our local group of galaxies since they are gravitational bound.

Traditional dark energy also cannot expand our local group of galaxies since its density holds constant while our local group remains the same size (see above) so the total local group dark energy remains constant.

However,

• 1) the dark energy density possibly could increase (leading to The Big Rip);
  2) or some sort of relativistic dark matter "radiation" could decrease (by redshift).

Indeed, I was not suggesting that our local group of galaxies is being expanded.

But our local group of galaxies only contains us, the Andromeda galaxy, M33, the Magellanic Clouds and a few others. Even the Virgo Group, only some 55 million light-years away from us, is slowly moving away from us, even though we are still gravitationally bound to it.

The galaxies whose Cepheids and supernovas Type Ia were used to obtain the new, higher value of the Hubble constant, are all outside our little Local Group and are all moving away from us. (The galaxies and supernovas were, by the way, M101 with 2011fe, NGC 1015 with 2009ig, NGC 1309 with 2002fk, NGC 1365 with 2012fr, NGC 1448 with 2001el, NGC 2442 with 2015F, NGC 3021 with 1995al, NGC 3370 with 1994 ae, NGC 3447 with 2012 ht, NGC 3972 with 2011by, NGC 3982 with 1998aq, NGC 4038 with 2007sr, NGC 4258 with water masers, NGC 4424 with 2012cg, NGC 4536 with 1981B, NGC 4639 with 1990N, NGC 5584 with 2007af, NGC 5917 with 2005cf, NGC 7250 with 2013dy, and UGC 9391 with 2003du.)

Ann

[neufer]

Could it simply be that dark energy is not only accelerating the universe, but it might just possibly be "accelerating itself", too?

The traditional big bang cannot expand our local group of galaxies since they are gravitational bound.

Traditional dark energy also cannot expand our local group of galaxies since its density holds constant while our local group remains the same size (see above) so the total local group dark energy remains constant.

However,

• 1) the dark energy density possibly could increase (leading to The Big Rip);
  2) or some sort of relativistic dark matter "radiation" could decrease (by redshift).

I was not suggesting that our local group of galaxies is being expanded.

To tell the truth, I could not quite understand exactly what you were suggesting by 'Could it simply be that dark energy is not only accelerating the universe, but it might just possibly be "accelerating itself", too?' so I tried to present the situation in a fashion that I might be able to understand it. (Which is what I generally do when I'm not cracking jokes.)

[Ann]

I was suggesting that dark energy was perhaps weaker when the universe was very young than it is now. The way I understand it, Planck looked at the cosmic microwave background when it came to the conclusion that dark energy was weaker than it had previously been thought to be. But the new HST survey concentrates on galaxies close enough for their Cepheids to be close enough for Hubble to make sense of.

Imagine that you came across a DNA sample from a baby born 25 years ago. After analyzing the DNA, you conclude, for example, that the child will grow up to be 180 centimeters tall. But then you actually meet the young man whose baby samples you have looked at, and he has grown to be 185 centimeters tall. Your original estimate was wrong, but why was it wrong? Imagine that the baby had an identical twin brother, but the brothers were separated at birth and grew up under very different circumstances. You locate the twin brother and find that he is only 175 centimeters tall.

I'm trying to speculate if the present rate of acceleration of the universe (if indeed it is accelerating that fast) was actually there for us to see in the the cosmic microwave background in such a way that we could predict the future of the universe from its message, or if there were hidden parameters there that only became obvious after a number of billion years.

Ann

[neufer]

I was suggesting that dark energy was perhaps weaker when the universe was very young than it is now.

Yes, but was it 'perhaps weaker' because its density was less or for some other reason.

[Ann]

I was suggesting that dark energy was perhaps weaker when the universe was very young than it is now.

Yes, but was it 'perhaps weaker' because its density was less or for some other reason.

Click to view full size image

Point taken. Speculations. Guesses.

Words, words, words.

Ann

[Evermore]

I was suggesting that dark energy was perhaps weaker when the universe was very young than it is now.

Yes, but was it 'perhaps weaker' because its density was less or for some other reason.

But how could its density be less when the universe has expanded so much? Unless it is constantly being created .. which some say is not possible, the old 'energy cannot be created or destroyed' frame of mind.

[Evermore]

I was suggesting that dark energy was perhaps weaker when the universe was very young than it is now.

Yes, but was it 'perhaps weaker' because its density was less or for some other reason.

Click to view full size image

Point taken. Speculations. Guesses.

Words, words, words.

Ann

Yes, but important speculation, important words, words, words .. for all science seems to be speculation at some point (or, indeed, at all points, as the 'laws' of physics seem not to be inviolable .. and as words, words, words seem to translate eventually into mathematical equations (which themselves do not seem to always add up to the same sum.)

[Evermore]

Yes, but was it 'perhaps weaker' because its density was less or for some other reason.

Click to view full size image

Point taken. Speculations. Guesses.

Words, words, words.

Ann

Yes, but important speculation, important words, words, words .. for all science seems to be speculation at some point (or, indeed, at all points, as the 'laws' of physics seem not to be inviolable .. and as words, words, words seem to translate eventually into mathematical equations (which themselves do not seem to always add up to the same sum.)

(as in my responses example .. with one or more 'brackets' being out of place perhaps equating to confusion.) ( ) )(()) dazzled by the lack of artistry.

[Evermore]

From Wiki: "... That is to say, no system without an external energy supply can deliver an unlimited amount of energy to its surroundings."

Okay, we know that energy can change forms .. however .. IF our universe (a system?) is not the ONLY universe, COULD we be receiving energy from ANOTHER universe .. or indeed from SOMETHING ELSE outside our universe? Now therein lies speculation.

[Evermore]

And indeed (I suppose I should register in this forum to gain freedom to edit, although that can work against itself, as one reader may read one unedited version while the next reader would read the edited version) .. to continue ...

... IF our universe was/is/will be receiving energy from another universe the laws in THAT universe MAY not match the laws in this universe .. so that energy COULD be created or destroyed .. sent here or there or wherever .. and speculation on those possibilities MIGHT result in new ways of transmitting energy here to power our for instance.

However .. I think the idea of powering s would create boundaries to the thought processes .. thereby dimming the speculative powers which are so attractive as an art form.

[neufer]

... IF our universe was/is/will be receiving energy from another universe the laws in THAT universe MAY not match the laws in this universe .. so that energy COULD be created or destroyed .. sent here or there or wherever .. and speculation on those possibilities MIGHT result in new ways of transmitting energy here to power our for instance.

That energy source would very thinly (and evenly) spread.

We are much better off using solar power.

[Evermore]

... IF our universe was/is/will be receiving energy from another universe the laws in THAT universe MAY not match the laws in this universe .. so that energy COULD be created or destroyed .. sent here or there or wherever .. and speculation on those possibilities MIGHT result in new ways of transmitting energy here to power our for instance.

That energy source would very thinly (and evenly) spread.

We are much better off using solar power.

Why not wind, Neufer?

[neufer]

Why not wind, Neufer?

Wind is good.